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README

1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arc			Files generic to ARC architecture
136    /cpu		CPU specific files
137      /arc700		Files specific to ARC 700 CPUs
138    /lib		Architecture specific library files
139  /arm			Files generic to ARM architecture
140    /cpu		CPU specific files
141      /arm720t		Files specific to ARM 720 CPUs
142      /arm920t		Files specific to ARM 920 CPUs
143	/at91		Files specific to Atmel AT91RM9200 CPU
144	/imx		Files specific to Freescale MC9328 i.MX CPUs
145	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
146      /arm926ejs	Files specific to ARM 926 CPUs
147      /arm1136		Files specific to ARM 1136 CPUs
148      /pxa		Files specific to Intel XScale PXA CPUs
149      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
150    /lib		Architecture specific library files
151  /avr32		Files generic to AVR32 architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /blackfin		Files generic to Analog Devices Blackfin architecture
155    /cpu		CPU specific files
156    /lib		Architecture specific library files
157  /m68k			Files generic to m68k architecture
158    /cpu		CPU specific files
159      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
160      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
161      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
162      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
163      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
164    /lib		Architecture specific library files
165  /microblaze		Files generic to microblaze architecture
166    /cpu		CPU specific files
167    /lib		Architecture specific library files
168  /mips			Files generic to MIPS architecture
169    /cpu		CPU specific files
170      /mips32		Files specific to MIPS32 CPUs
171      /mips64		Files specific to MIPS64 CPUs
172    /lib		Architecture specific library files
173  /nds32		Files generic to NDS32 architecture
174    /cpu		CPU specific files
175      /n1213		Files specific to Andes Technology N1213 CPUs
176    /lib		Architecture specific library files
177  /nios2		Files generic to Altera NIOS2 architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /openrisc		Files generic to OpenRISC architecture
181    /cpu		CPU specific files
182    /lib		Architecture specific library files
183  /powerpc		Files generic to PowerPC architecture
184    /cpu		CPU specific files
185      /mpc5xx		Files specific to Freescale MPC5xx CPUs
186      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
187      /mpc8xx		Files specific to Freescale MPC8xx CPUs
188      /mpc8260		Files specific to Freescale MPC8260 CPUs
189      /mpc85xx		Files specific to Freescale MPC85xx CPUs
190      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
191    /lib		Architecture specific library files
192  /sh			Files generic to SH architecture
193    /cpu		CPU specific files
194      /sh2		Files specific to sh2 CPUs
195      /sh3		Files specific to sh3 CPUs
196      /sh4		Files specific to sh4 CPUs
197    /lib		Architecture specific library files
198  /sparc		Files generic to SPARC architecture
199    /cpu		CPU specific files
200      /leon2		Files specific to Gaisler LEON2 SPARC CPU
201      /leon3		Files specific to Gaisler LEON3 SPARC CPU
202    /lib		Architecture specific library files
203  /x86			Files generic to x86 architecture
204    /cpu		CPU specific files
205    /lib		Architecture specific library files
206/api			Machine/arch independent API for external apps
207/board			Board dependent files
208/common			Misc architecture independent functions
209/disk			Code for disk drive partition handling
210/doc			Documentation (don't expect too much)
211/drivers		Commonly used device drivers
212/dts			Contains Makefile for building internal U-Boot fdt.
213/examples		Example code for standalone applications, etc.
214/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
215/include		Header Files
216/lib			Files generic to all architectures
217  /libfdt		Library files to support flattened device trees
218  /lzma			Library files to support LZMA decompression
219  /lzo			Library files to support LZO decompression
220/net			Networking code
221/post			Power On Self Test
222/spl			Secondary Program Loader framework
223/tools			Tools to build S-Record or U-Boot images, etc.
224
225Software Configuration:
226=======================
227
228Configuration is usually done using C preprocessor defines; the
229rationale behind that is to avoid dead code whenever possible.
230
231There are two classes of configuration variables:
232
233* Configuration _OPTIONS_:
234  These are selectable by the user and have names beginning with
235  "CONFIG_".
236
237* Configuration _SETTINGS_:
238  These depend on the hardware etc. and should not be meddled with if
239  you don't know what you're doing; they have names beginning with
240  "CONFIG_SYS_".
241
242Later we will add a configuration tool - probably similar to or even
243identical to what's used for the Linux kernel. Right now, we have to
244do the configuration by hand, which means creating some symbolic
245links and editing some configuration files. We use the TQM8xxL boards
246as an example here.
247
248
249Selection of Processor Architecture and Board Type:
250---------------------------------------------------
251
252For all supported boards there are ready-to-use default
253configurations available; just type "make <board_name>_defconfig".
254
255Example: For a TQM823L module type:
256
257	cd u-boot
258	make TQM823L_defconfig
259
260For the Cogent platform, you need to specify the CPU type as well;
261e.g. "make cogent_mpc8xx_defconfig". And also configure the cogent
262directory according to the instructions in cogent/README.
263
264
265Sandbox Environment:
266--------------------
267
268U-Boot can be built natively to run on a Linux host using the 'sandbox'
269board. This allows feature development which is not board- or architecture-
270specific to be undertaken on a native platform. The sandbox is also used to
271run some of U-Boot's tests.
272
273See board/sandbox/README.sandbox for more details.
274
275
276Board Initialisation Flow:
277--------------------------
278
279This is the intended start-up flow for boards. This should apply for both
280SPL and U-Boot proper (i.e. they both follow the same rules). At present SPL
281mostly uses a separate code path, but the funtion names and roles of each
282function are the same. Some boards or architectures may not conform to this.
283At least most ARM boards which use CONFIG_SPL_FRAMEWORK conform to this.
284
285Execution starts with start.S with three functions called during init after
286that. The purpose and limitations of each is described below.
287
288lowlevel_init():
289	- purpose: essential init to permit execution to reach board_init_f()
290	- no global_data or BSS
291	- there is no stack (ARMv7 may have one but it will soon be removed)
292	- must not set up SDRAM or use console
293	- must only do the bare minimum to allow execution to continue to
294		board_init_f()
295	- this is almost never needed
296	- return normally from this function
297
298board_init_f():
299	- purpose: set up the machine ready for running board_init_r():
300		i.e. SDRAM and serial UART
301	- global_data is available
302	- stack is in SRAM
303	- BSS is not available, so you cannot use global/static variables,
304		only stack variables and global_data
305
306	Non-SPL-specific notes:
307	- dram_init() is called to set up DRAM. If already done in SPL this
308		can do nothing
309
310	SPL-specific notes:
311	- you can override the entire board_init_f() function with your own
312		version as needed.
313	- preloader_console_init() can be called here in extremis
314	- should set up SDRAM, and anything needed to make the UART work
315	- these is no need to clear BSS, it will be done by crt0.S
316	- must return normally from this function (don't call board_init_r()
317		directly)
318
319Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
320this point the stack and global_data are relocated to below
321CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
322memory.
323
324board_init_r():
325	- purpose: main execution, common code
326	- global_data is available
327	- SDRAM is available
328	- BSS is available, all static/global variables can be used
329	- execution eventually continues to main_loop()
330
331	Non-SPL-specific notes:
332	- U-Boot is relocated to the top of memory and is now running from
333		there.
334
335	SPL-specific notes:
336	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
337		CONFIG_SPL_STACK_R_ADDR points into SDRAM
338	- preloader_console_init() can be called here - typically this is
339		done by defining CONFIG_SPL_BOARD_INIT and then supplying a
340		spl_board_init() function containing this call
341	- loads U-Boot or (in falcon mode) Linux
342
343
344
345Configuration Options:
346----------------------
347
348Configuration depends on the combination of board and CPU type; all
349such information is kept in a configuration file
350"include/configs/<board_name>.h".
351
352Example: For a TQM823L module, all configuration settings are in
353"include/configs/TQM823L.h".
354
355
356Many of the options are named exactly as the corresponding Linux
357kernel configuration options. The intention is to make it easier to
358build a config tool - later.
359
360
361The following options need to be configured:
362
363- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
364
365- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
366
367- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
368		Define exactly one, e.g. CONFIG_ATSTK1002
369
370- CPU Module Type: (if CONFIG_COGENT is defined)
371		Define exactly one of
372		CONFIG_CMA286_60_OLD
373--- FIXME --- not tested yet:
374		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
375		CONFIG_CMA287_23, CONFIG_CMA287_50
376
377- Motherboard Type: (if CONFIG_COGENT is defined)
378		Define exactly one of
379		CONFIG_CMA101, CONFIG_CMA102
380
381- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
382		Define one or more of
383		CONFIG_CMA302
384
385- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
386		Define one or more of
387		CONFIG_LCD_HEARTBEAT	- update a character position on
388					  the LCD display every second with
389					  a "rotator" |\-/|\-/
390
391- Marvell Family Member
392		CONFIG_SYS_MVFS		- define it if you want to enable
393					  multiple fs option at one time
394					  for marvell soc family
395
396- 8xx CPU Options: (if using an MPC8xx CPU)
397		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
398					  get_gclk_freq() cannot work
399					  e.g. if there is no 32KHz
400					  reference PIT/RTC clock
401		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
402					  or XTAL/EXTAL)
403
404- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
405		CONFIG_SYS_8xx_CPUCLK_MIN
406		CONFIG_SYS_8xx_CPUCLK_MAX
407		CONFIG_8xx_CPUCLK_DEFAULT
408			See doc/README.MPC866
409
410		CONFIG_SYS_MEASURE_CPUCLK
411
412		Define this to measure the actual CPU clock instead
413		of relying on the correctness of the configured
414		values. Mostly useful for board bringup to make sure
415		the PLL is locked at the intended frequency. Note
416		that this requires a (stable) reference clock (32 kHz
417		RTC clock or CONFIG_SYS_8XX_XIN)
418
419		CONFIG_SYS_DELAYED_ICACHE
420
421		Define this option if you want to enable the
422		ICache only when Code runs from RAM.
423
424- 85xx CPU Options:
425		CONFIG_SYS_PPC64
426
427		Specifies that the core is a 64-bit PowerPC implementation (implements
428		the "64" category of the Power ISA). This is necessary for ePAPR
429		compliance, among other possible reasons.
430
431		CONFIG_SYS_FSL_TBCLK_DIV
432
433		Defines the core time base clock divider ratio compared to the
434		system clock.  On most PQ3 devices this is 8, on newer QorIQ
435		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
436
437		CONFIG_SYS_FSL_PCIE_COMPAT
438
439		Defines the string to utilize when trying to match PCIe device
440		tree nodes for the given platform.
441
442		CONFIG_SYS_PPC_E500_DEBUG_TLB
443
444		Enables a temporary TLB entry to be used during boot to work
445		around limitations in e500v1 and e500v2 external debugger
446		support. This reduces the portions of the boot code where
447		breakpoints and single stepping do not work.  The value of this
448		symbol should be set to the TLB1 entry to be used for this
449		purpose.
450
451		CONFIG_SYS_FSL_ERRATUM_A004510
452
453		Enables a workaround for erratum A004510.  If set,
454		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
455		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
456
457		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
458		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
459
460		Defines one or two SoC revisions (low 8 bits of SVR)
461		for which the A004510 workaround should be applied.
462
463		The rest of SVR is either not relevant to the decision
464		of whether the erratum is present (e.g. p2040 versus
465		p2041) or is implied by the build target, which controls
466		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
467
468		See Freescale App Note 4493 for more information about
469		this erratum.
470
471		CONFIG_A003399_NOR_WORKAROUND
472		Enables a workaround for IFC erratum A003399. It is only
473		required during NOR boot.
474
475		CONFIG_A008044_WORKAROUND
476		Enables a workaround for T1040/T1042 erratum A008044. It is only
477		required during NAND boot and valid for Rev 1.0 SoC revision
478
479		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
480
481		This is the value to write into CCSR offset 0x18600
482		according to the A004510 workaround.
483
484		CONFIG_SYS_FSL_DSP_DDR_ADDR
485		This value denotes start offset of DDR memory which is
486		connected exclusively to the DSP cores.
487
488		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
489		This value denotes start offset of M2 memory
490		which is directly connected to the DSP core.
491
492		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
493		This value denotes start offset of M3 memory which is directly
494		connected to the DSP core.
495
496		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
497		This value denotes start offset of DSP CCSR space.
498
499		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
500		Single Source Clock is clocking mode present in some of FSL SoC's.
501		In this mode, a single differential clock is used to supply
502		clocks to the sysclock, ddrclock and usbclock.
503
504		CONFIG_SYS_CPC_REINIT_F
505		This CONFIG is defined when the CPC is configured as SRAM at the
506		time of U-boot entry and is required to be re-initialized.
507
508		CONFIG_DEEP_SLEEP
509		Indicates this SoC supports deep sleep feature. If deep sleep is
510		supported, core will start to execute uboot when wakes up.
511
512- Generic CPU options:
513		CONFIG_SYS_GENERIC_GLOBAL_DATA
514		Defines global data is initialized in generic board board_init_f().
515		If this macro is defined, global data is created and cleared in
516		generic board board_init_f(). Without this macro, architecture/board
517		should initialize global data before calling board_init_f().
518
519		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
520
521		Defines the endianess of the CPU. Implementation of those
522		values is arch specific.
523
524		CONFIG_SYS_FSL_DDR
525		Freescale DDR driver in use. This type of DDR controller is
526		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
527		SoCs.
528
529		CONFIG_SYS_FSL_DDR_ADDR
530		Freescale DDR memory-mapped register base.
531
532		CONFIG_SYS_FSL_DDR_EMU
533		Specify emulator support for DDR. Some DDR features such as
534		deskew training are not available.
535
536		CONFIG_SYS_FSL_DDRC_GEN1
537		Freescale DDR1 controller.
538
539		CONFIG_SYS_FSL_DDRC_GEN2
540		Freescale DDR2 controller.
541
542		CONFIG_SYS_FSL_DDRC_GEN3
543		Freescale DDR3 controller.
544
545		CONFIG_SYS_FSL_DDRC_GEN4
546		Freescale DDR4 controller.
547
548		CONFIG_SYS_FSL_DDRC_ARM_GEN3
549		Freescale DDR3 controller for ARM-based SoCs.
550
551		CONFIG_SYS_FSL_DDR1
552		Board config to use DDR1. It can be enabled for SoCs with
553		Freescale DDR1 or DDR2 controllers, depending on the board
554		implemetation.
555
556		CONFIG_SYS_FSL_DDR2
557		Board config to use DDR2. It can be eanbeld for SoCs with
558		Freescale DDR2 or DDR3 controllers, depending on the board
559		implementation.
560
561		CONFIG_SYS_FSL_DDR3
562		Board config to use DDR3. It can be enabled for SoCs with
563		Freescale DDR3 or DDR3L controllers.
564
565		CONFIG_SYS_FSL_DDR3L
566		Board config to use DDR3L. It can be enabled for SoCs with
567		DDR3L controllers.
568
569		CONFIG_SYS_FSL_DDR4
570		Board config to use DDR4. It can be enabled for SoCs with
571		DDR4 controllers.
572
573		CONFIG_SYS_FSL_IFC_BE
574		Defines the IFC controller register space as Big Endian
575
576		CONFIG_SYS_FSL_IFC_LE
577		Defines the IFC controller register space as Little Endian
578
579		CONFIG_SYS_FSL_PBL_PBI
580		It enables addition of RCW (Power on reset configuration) in built image.
581		Please refer doc/README.pblimage for more details
582
583		CONFIG_SYS_FSL_PBL_RCW
584		It adds PBI(pre-boot instructions) commands in u-boot build image.
585		PBI commands can be used to configure SoC before it starts the execution.
586		Please refer doc/README.pblimage for more details
587
588		CONFIG_SPL_FSL_PBL
589		It adds a target to create boot binary having SPL binary in PBI format
590		concatenated with u-boot binary.
591
592		CONFIG_SYS_FSL_DDR_BE
593		Defines the DDR controller register space as Big Endian
594
595		CONFIG_SYS_FSL_DDR_LE
596		Defines the DDR controller register space as Little Endian
597
598		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
599		Physical address from the view of DDR controllers. It is the
600		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
601		it could be different for ARM SoCs.
602
603		CONFIG_SYS_FSL_DDR_INTLV_256B
604		DDR controller interleaving on 256-byte. This is a special
605		interleaving mode, handled by Dickens for Freescale layerscape
606		SoCs with ARM core.
607
608		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
609		Number of controllers used as main memory.
610
611		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
612		Number of controllers used for other than main memory.
613
614		CONFIG_SYS_FSL_HAS_DP_DDR
615		Defines the SoC has DP-DDR used for DPAA.
616
617		CONFIG_SYS_FSL_SEC_BE
618		Defines the SEC controller register space as Big Endian
619
620		CONFIG_SYS_FSL_SEC_LE
621		Defines the SEC controller register space as Little Endian
622
623- Intel Monahans options:
624		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
625
626		Defines the Monahans run mode to oscillator
627		ratio. Valid values are 8, 16, 24, 31. The core
628		frequency is this value multiplied by 13 MHz.
629
630		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
631
632		Defines the Monahans turbo mode to oscillator
633		ratio. Valid values are 1 (default if undefined) and
634		2. The core frequency as calculated above is multiplied
635		by this value.
636
637- MIPS CPU options:
638		CONFIG_SYS_INIT_SP_OFFSET
639
640		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
641		pointer. This is needed for the temporary stack before
642		relocation.
643
644		CONFIG_SYS_MIPS_CACHE_MODE
645
646		Cache operation mode for the MIPS CPU.
647		See also arch/mips/include/asm/mipsregs.h.
648		Possible values are:
649			CONF_CM_CACHABLE_NO_WA
650			CONF_CM_CACHABLE_WA
651			CONF_CM_UNCACHED
652			CONF_CM_CACHABLE_NONCOHERENT
653			CONF_CM_CACHABLE_CE
654			CONF_CM_CACHABLE_COW
655			CONF_CM_CACHABLE_CUW
656			CONF_CM_CACHABLE_ACCELERATED
657
658		CONFIG_SYS_XWAY_EBU_BOOTCFG
659
660		Special option for Lantiq XWAY SoCs for booting from NOR flash.
661		See also arch/mips/cpu/mips32/start.S.
662
663		CONFIG_XWAY_SWAP_BYTES
664
665		Enable compilation of tools/xway-swap-bytes needed for Lantiq
666		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
667		be swapped if a flash programmer is used.
668
669- ARM options:
670		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
671
672		Select high exception vectors of the ARM core, e.g., do not
673		clear the V bit of the c1 register of CP15.
674
675		CONFIG_SYS_THUMB_BUILD
676
677		Use this flag to build U-Boot using the Thumb instruction
678		set for ARM architectures. Thumb instruction set provides
679		better code density. For ARM architectures that support
680		Thumb2 this flag will result in Thumb2 code generated by
681		GCC.
682
683		CONFIG_ARM_ERRATA_716044
684		CONFIG_ARM_ERRATA_742230
685		CONFIG_ARM_ERRATA_743622
686		CONFIG_ARM_ERRATA_751472
687		CONFIG_ARM_ERRATA_761320
688		CONFIG_ARM_ERRATA_773022
689		CONFIG_ARM_ERRATA_774769
690		CONFIG_ARM_ERRATA_794072
691
692		If set, the workarounds for these ARM errata are applied early
693		during U-Boot startup. Note that these options force the
694		workarounds to be applied; no CPU-type/version detection
695		exists, unlike the similar options in the Linux kernel. Do not
696		set these options unless they apply!
697
698		COUNTER_FREQUENCY
699		Generic timer clock source frequency.
700
701		COUNTER_FREQUENCY_REAL
702		Generic timer clock source frequency if the real clock is
703		different from COUNTER_FREQUENCY, and can only be determined
704		at run time.
705
706		NOTE: The following can be machine specific errata. These
707		do have ability to provide rudimentary version and machine
708		specific checks, but expect no product checks.
709		CONFIG_ARM_ERRATA_430973
710		CONFIG_ARM_ERRATA_454179
711		CONFIG_ARM_ERRATA_621766
712		CONFIG_ARM_ERRATA_798870
713		CONFIG_ARM_ERRATA_801819
714
715- Tegra SoC options:
716		CONFIG_TEGRA_SUPPORT_NON_SECURE
717
718		Support executing U-Boot in non-secure (NS) mode. Certain
719		impossible actions will be skipped if the CPU is in NS mode,
720		such as ARM architectural timer initialization.
721
722- Linux Kernel Interface:
723		CONFIG_CLOCKS_IN_MHZ
724
725		U-Boot stores all clock information in Hz
726		internally. For binary compatibility with older Linux
727		kernels (which expect the clocks passed in the
728		bd_info data to be in MHz) the environment variable
729		"clocks_in_mhz" can be defined so that U-Boot
730		converts clock data to MHZ before passing it to the
731		Linux kernel.
732		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
733		"clocks_in_mhz=1" is automatically included in the
734		default environment.
735
736		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
737
738		When transferring memsize parameter to Linux, some versions
739		expect it to be in bytes, others in MB.
740		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
741
742		CONFIG_OF_LIBFDT
743
744		New kernel versions are expecting firmware settings to be
745		passed using flattened device trees (based on open firmware
746		concepts).
747
748		CONFIG_OF_LIBFDT
749		 * New libfdt-based support
750		 * Adds the "fdt" command
751		 * The bootm command automatically updates the fdt
752
753		OF_CPU - The proper name of the cpus node (only required for
754			MPC512X and MPC5xxx based boards).
755		OF_SOC - The proper name of the soc node (only required for
756			MPC512X and MPC5xxx based boards).
757		OF_TBCLK - The timebase frequency.
758		OF_STDOUT_PATH - The path to the console device
759
760		boards with QUICC Engines require OF_QE to set UCC MAC
761		addresses
762
763		CONFIG_OF_BOARD_SETUP
764
765		Board code has addition modification that it wants to make
766		to the flat device tree before handing it off to the kernel
767
768		CONFIG_OF_SYSTEM_SETUP
769
770		Other code has addition modification that it wants to make
771		to the flat device tree before handing it off to the kernel.
772		This causes ft_system_setup() to be called before booting
773		the kernel.
774
775		CONFIG_OF_BOOT_CPU
776
777		This define fills in the correct boot CPU in the boot
778		param header, the default value is zero if undefined.
779
780		CONFIG_OF_IDE_FIXUP
781
782		U-Boot can detect if an IDE device is present or not.
783		If not, and this new config option is activated, U-Boot
784		removes the ATA node from the DTS before booting Linux,
785		so the Linux IDE driver does not probe the device and
786		crash. This is needed for buggy hardware (uc101) where
787		no pull down resistor is connected to the signal IDE5V_DD7.
788
789		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
790
791		This setting is mandatory for all boards that have only one
792		machine type and must be used to specify the machine type
793		number as it appears in the ARM machine registry
794		(see http://www.arm.linux.org.uk/developer/machines/).
795		Only boards that have multiple machine types supported
796		in a single configuration file and the machine type is
797		runtime discoverable, do not have to use this setting.
798
799- vxWorks boot parameters:
800
801		bootvx constructs a valid bootline using the following
802		environments variables: bootdev, bootfile, ipaddr, netmask,
803		serverip, gatewayip, hostname, othbootargs.
804		It loads the vxWorks image pointed bootfile.
805
806		Note: If a "bootargs" environment is defined, it will overwride
807		the defaults discussed just above.
808
809- Cache Configuration:
810		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
811		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
812		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
813
814- Cache Configuration for ARM:
815		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
816				      controller
817		CONFIG_SYS_PL310_BASE - Physical base address of PL310
818					controller register space
819
820- Serial Ports:
821		CONFIG_PL010_SERIAL
822
823		Define this if you want support for Amba PrimeCell PL010 UARTs.
824
825		CONFIG_PL011_SERIAL
826
827		Define this if you want support for Amba PrimeCell PL011 UARTs.
828
829		CONFIG_PL011_CLOCK
830
831		If you have Amba PrimeCell PL011 UARTs, set this variable to
832		the clock speed of the UARTs.
833
834		CONFIG_PL01x_PORTS
835
836		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
837		define this to a list of base addresses for each (supported)
838		port. See e.g. include/configs/versatile.h
839
840		CONFIG_SERIAL_HW_FLOW_CONTROL
841
842		Define this variable to enable hw flow control in serial driver.
843		Current user of this option is drivers/serial/nsl16550.c driver
844
845- Console Interface:
846		Depending on board, define exactly one serial port
847		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
848		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
849		console by defining CONFIG_8xx_CONS_NONE
850
851		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
852		port routines must be defined elsewhere
853		(i.e. serial_init(), serial_getc(), ...)
854
855		CONFIG_CFB_CONSOLE
856		Enables console device for a color framebuffer. Needs following
857		defines (cf. smiLynxEM, i8042)
858			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
859						(default big endian)
860			VIDEO_HW_RECTFILL	graphic chip supports
861						rectangle fill
862						(cf. smiLynxEM)
863			VIDEO_HW_BITBLT		graphic chip supports
864						bit-blit (cf. smiLynxEM)
865			VIDEO_VISIBLE_COLS	visible pixel columns
866						(cols=pitch)
867			VIDEO_VISIBLE_ROWS	visible pixel rows
868			VIDEO_PIXEL_SIZE	bytes per pixel
869			VIDEO_DATA_FORMAT	graphic data format
870						(0-5, cf. cfb_console.c)
871			VIDEO_FB_ADRS		framebuffer address
872			VIDEO_KBD_INIT_FCT	keyboard int fct
873						(i.e. rx51_kp_init())
874			VIDEO_TSTC_FCT		test char fct
875						(i.e. rx51_kp_tstc)
876			VIDEO_GETC_FCT		get char fct
877						(i.e. rx51_kp_getc)
878			CONFIG_VIDEO_LOGO	display Linux logo in
879						upper left corner
880			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
881						linux_logo.h for logo.
882						Requires CONFIG_VIDEO_LOGO
883			CONFIG_CONSOLE_EXTRA_INFO
884						additional board info beside
885						the logo
886
887		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
888		a limited number of ANSI escape sequences (cursor control,
889		erase functions and limited graphics rendition control).
890
891		When CONFIG_CFB_CONSOLE is defined, video console is
892		default i/o. Serial console can be forced with
893		environment 'console=serial'.
894
895		When CONFIG_SILENT_CONSOLE is defined, all console
896		messages (by U-Boot and Linux!) can be silenced with
897		the "silent" environment variable. See
898		doc/README.silent for more information.
899
900		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
901			is 0x00.
902		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
903			is 0xa0.
904
905- Console Baudrate:
906		CONFIG_BAUDRATE - in bps
907		Select one of the baudrates listed in
908		CONFIG_SYS_BAUDRATE_TABLE, see below.
909		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
910
911- Console Rx buffer length
912		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
913		the maximum receive buffer length for the SMC.
914		This option is actual only for 82xx and 8xx possible.
915		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
916		must be defined, to setup the maximum idle timeout for
917		the SMC.
918
919- Pre-Console Buffer:
920		Prior to the console being initialised (i.e. serial UART
921		initialised etc) all console output is silently discarded.
922		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
923		buffer any console messages prior to the console being
924		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
925		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
926		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
927		bytes are output before the console is initialised, the
928		earlier bytes are discarded.
929
930		Note that when printing the buffer a copy is made on the
931		stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack.
932
933		'Sane' compilers will generate smaller code if
934		CONFIG_PRE_CON_BUF_SZ is a power of 2
935
936- Safe printf() functions
937		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
938		the printf() functions. These are defined in
939		include/vsprintf.h and include snprintf(), vsnprintf() and
940		so on. Code size increase is approximately 300-500 bytes.
941		If this option is not given then these functions will
942		silently discard their buffer size argument - this means
943		you are not getting any overflow checking in this case.
944
945- Boot Delay:	CONFIG_BOOTDELAY - in seconds
946		Delay before automatically booting the default image;
947		set to -1 to disable autoboot.
948		set to -2 to autoboot with no delay and not check for abort
949		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
950
951		See doc/README.autoboot for these options that
952		work with CONFIG_BOOTDELAY. None are required.
953		CONFIG_BOOT_RETRY_TIME
954		CONFIG_BOOT_RETRY_MIN
955		CONFIG_AUTOBOOT_KEYED
956		CONFIG_AUTOBOOT_PROMPT
957		CONFIG_AUTOBOOT_DELAY_STR
958		CONFIG_AUTOBOOT_STOP_STR
959		CONFIG_ZERO_BOOTDELAY_CHECK
960		CONFIG_RESET_TO_RETRY
961
962- Autoboot Command:
963		CONFIG_BOOTCOMMAND
964		Only needed when CONFIG_BOOTDELAY is enabled;
965		define a command string that is automatically executed
966		when no character is read on the console interface
967		within "Boot Delay" after reset.
968
969		CONFIG_BOOTARGS
970		This can be used to pass arguments to the bootm
971		command. The value of CONFIG_BOOTARGS goes into the
972		environment value "bootargs".
973
974		CONFIG_RAMBOOT and CONFIG_NFSBOOT
975		The value of these goes into the environment as
976		"ramboot" and "nfsboot" respectively, and can be used
977		as a convenience, when switching between booting from
978		RAM and NFS.
979
980- Bootcount:
981		CONFIG_BOOTCOUNT_LIMIT
982		Implements a mechanism for detecting a repeating reboot
983		cycle, see:
984		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
985
986		CONFIG_BOOTCOUNT_ENV
987		If no softreset save registers are found on the hardware
988		"bootcount" is stored in the environment. To prevent a
989		saveenv on all reboots, the environment variable
990		"upgrade_available" is used. If "upgrade_available" is
991		0, "bootcount" is always 0, if "upgrade_available" is
992		1 "bootcount" is incremented in the environment.
993		So the Userspace Applikation must set the "upgrade_available"
994		and "bootcount" variable to 0, if a boot was successfully.
995
996- Pre-Boot Commands:
997		CONFIG_PREBOOT
998
999		When this option is #defined, the existence of the
1000		environment variable "preboot" will be checked
1001		immediately before starting the CONFIG_BOOTDELAY
1002		countdown and/or running the auto-boot command resp.
1003		entering interactive mode.
1004
1005		This feature is especially useful when "preboot" is
1006		automatically generated or modified. For an example
1007		see the LWMON board specific code: here "preboot" is
1008		modified when the user holds down a certain
1009		combination of keys on the (special) keyboard when
1010		booting the systems
1011
1012- Serial Download Echo Mode:
1013		CONFIG_LOADS_ECHO
1014		If defined to 1, all characters received during a
1015		serial download (using the "loads" command) are
1016		echoed back. This might be needed by some terminal
1017		emulations (like "cu"), but may as well just take
1018		time on others. This setting #define's the initial
1019		value of the "loads_echo" environment variable.
1020
1021- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
1022		CONFIG_KGDB_BAUDRATE
1023		Select one of the baudrates listed in
1024		CONFIG_SYS_BAUDRATE_TABLE, see below.
1025
1026- Monitor Functions:
1027		Monitor commands can be included or excluded
1028		from the build by using the #include files
1029		<config_cmd_all.h> and #undef'ing unwanted
1030		commands, or adding #define's for wanted commands.
1031
1032		The default command configuration includes all commands
1033		except those marked below with a "*".
1034
1035		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
1036		CONFIG_CMD_ASKENV	* ask for env variable
1037		CONFIG_CMD_BDI		  bdinfo
1038		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
1039		CONFIG_CMD_BMP		* BMP support
1040		CONFIG_CMD_BSP		* Board specific commands
1041		CONFIG_CMD_BOOTD	  bootd
1042		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
1043		CONFIG_CMD_CACHE	* icache, dcache
1044		CONFIG_CMD_CLK   	* clock command support
1045		CONFIG_CMD_CONSOLE	  coninfo
1046		CONFIG_CMD_CRC32	* crc32
1047		CONFIG_CMD_DATE		* support for RTC, date/time...
1048		CONFIG_CMD_DHCP		* DHCP support
1049		CONFIG_CMD_DIAG		* Diagnostics
1050		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
1051		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
1052		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
1053		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
1054		CONFIG_CMD_DTT		* Digital Therm and Thermostat
1055		CONFIG_CMD_ECHO		  echo arguments
1056		CONFIG_CMD_EDITENV	  edit env variable
1057		CONFIG_CMD_EEPROM	* EEPROM read/write support
1058		CONFIG_CMD_ELF		* bootelf, bootvx
1059		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
1060		CONFIG_CMD_ENV_FLAGS	* display details about env flags
1061		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
1062		CONFIG_CMD_EXPORTENV	* export the environment
1063		CONFIG_CMD_EXT2		* ext2 command support
1064		CONFIG_CMD_EXT4		* ext4 command support
1065		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
1066					  that work for multiple fs types
1067		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
1068		CONFIG_CMD_SAVEENV	  saveenv
1069		CONFIG_CMD_FDC		* Floppy Disk Support
1070		CONFIG_CMD_FAT		* FAT command support
1071		CONFIG_CMD_FLASH	  flinfo, erase, protect
1072		CONFIG_CMD_FPGA		  FPGA device initialization support
1073		CONFIG_CMD_FUSE		* Device fuse support
1074		CONFIG_CMD_GETTIME	* Get time since boot
1075		CONFIG_CMD_GO		* the 'go' command (exec code)
1076		CONFIG_CMD_GREPENV	* search environment
1077		CONFIG_CMD_HASH		* calculate hash / digest
1078		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
1079		CONFIG_CMD_I2C		* I2C serial bus support
1080		CONFIG_CMD_IDE		* IDE harddisk support
1081		CONFIG_CMD_IMI		  iminfo
1082		CONFIG_CMD_IMLS		  List all images found in NOR flash
1083		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
1084		CONFIG_CMD_IMMAP	* IMMR dump support
1085		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
1086		CONFIG_CMD_IMPORTENV	* import an environment
1087		CONFIG_CMD_INI		* import data from an ini file into the env
1088		CONFIG_CMD_IRQ		* irqinfo
1089		CONFIG_CMD_ITEST	  Integer/string test of 2 values
1090		CONFIG_CMD_JFFS2	* JFFS2 Support
1091		CONFIG_CMD_KGDB		* kgdb
1092		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
1093		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
1094					  (169.254.*.*)
1095		CONFIG_CMD_LOADB	  loadb
1096		CONFIG_CMD_LOADS	  loads
1097		CONFIG_CMD_MD5SUM	* print md5 message digest
1098					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
1099		CONFIG_CMD_MEMINFO	* Display detailed memory information
1100		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
1101					  loop, loopw
1102		CONFIG_CMD_MEMTEST	* mtest
1103		CONFIG_CMD_MISC		  Misc functions like sleep etc
1104		CONFIG_CMD_MMC		* MMC memory mapped support
1105		CONFIG_CMD_MII		* MII utility commands
1106		CONFIG_CMD_MTDPARTS	* MTD partition support
1107		CONFIG_CMD_NAND		* NAND support
1108		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
1109		CONFIG_CMD_NFS		  NFS support
1110		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1111		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1112		CONFIG_CMD_PCI		* pciinfo
1113		CONFIG_CMD_PCMCIA		* PCMCIA support
1114		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1115					  host
1116		CONFIG_CMD_PORTIO	* Port I/O
1117		CONFIG_CMD_READ		* Read raw data from partition
1118		CONFIG_CMD_REGINFO	* Register dump
1119		CONFIG_CMD_RUN		  run command in env variable
1120		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1121		CONFIG_CMD_SAVES	* save S record dump
1122		CONFIG_CMD_SCSI		* SCSI Support
1123		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1124					  (requires CONFIG_CMD_I2C)
1125		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1126					  (4xx only)
1127		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1128		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1129					  (requires CONFIG_CMD_MEMORY)
1130		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1131		CONFIG_CMD_SOURCE	  "source" command Support
1132		CONFIG_CMD_SPI		* SPI serial bus support
1133		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1134		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1135		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1136		CONFIG_CMD_TIMER	* access to the system tick timer
1137		CONFIG_CMD_USB		* USB support
1138		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1139		CONFIG_CMD_MFSL		* Microblaze FSL support
1140		CONFIG_CMD_XIMG		  Load part of Multi Image
1141		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1142
1143		EXAMPLE: If you want all functions except of network
1144		support you can write:
1145
1146		#include "config_cmd_all.h"
1147		#undef CONFIG_CMD_NET
1148
1149	Other Commands:
1150		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1151
1152	Note:	Don't enable the "icache" and "dcache" commands
1153		(configuration option CONFIG_CMD_CACHE) unless you know
1154		what you (and your U-Boot users) are doing. Data
1155		cache cannot be enabled on systems like the 8xx or
1156		8260 (where accesses to the IMMR region must be
1157		uncached), and it cannot be disabled on all other
1158		systems where we (mis-) use the data cache to hold an
1159		initial stack and some data.
1160
1161
1162		XXX - this list needs to get updated!
1163
1164- Regular expression support:
1165		CONFIG_REGEX
1166		If this variable is defined, U-Boot is linked against
1167		the SLRE (Super Light Regular Expression) library,
1168		which adds regex support to some commands, as for
1169		example "env grep" and "setexpr".
1170
1171- Device tree:
1172		CONFIG_OF_CONTROL
1173		If this variable is defined, U-Boot will use a device tree
1174		to configure its devices, instead of relying on statically
1175		compiled #defines in the board file. This option is
1176		experimental and only available on a few boards. The device
1177		tree is available in the global data as gd->fdt_blob.
1178
1179		U-Boot needs to get its device tree from somewhere. This can
1180		be done using one of the two options below:
1181
1182		CONFIG_OF_EMBED
1183		If this variable is defined, U-Boot will embed a device tree
1184		binary in its image. This device tree file should be in the
1185		board directory and called <soc>-<board>.dts. The binary file
1186		is then picked up in board_init_f() and made available through
1187		the global data structure as gd->blob.
1188
1189		CONFIG_OF_SEPARATE
1190		If this variable is defined, U-Boot will build a device tree
1191		binary. It will be called u-boot.dtb. Architecture-specific
1192		code will locate it at run-time. Generally this works by:
1193
1194			cat u-boot.bin u-boot.dtb >image.bin
1195
1196		and in fact, U-Boot does this for you, creating a file called
1197		u-boot-dtb.bin which is useful in the common case. You can
1198		still use the individual files if you need something more
1199		exotic.
1200
1201- Watchdog:
1202		CONFIG_WATCHDOG
1203		If this variable is defined, it enables watchdog
1204		support for the SoC. There must be support in the SoC
1205		specific code for a watchdog. For the 8xx and 8260
1206		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1207		register.  When supported for a specific SoC is
1208		available, then no further board specific code should
1209		be needed to use it.
1210
1211		CONFIG_HW_WATCHDOG
1212		When using a watchdog circuitry external to the used
1213		SoC, then define this variable and provide board
1214		specific code for the "hw_watchdog_reset" function.
1215
1216		CONFIG_AT91_HW_WDT_TIMEOUT
1217		specify the timeout in seconds. default 2 seconds.
1218
1219- U-Boot Version:
1220		CONFIG_VERSION_VARIABLE
1221		If this variable is defined, an environment variable
1222		named "ver" is created by U-Boot showing the U-Boot
1223		version as printed by the "version" command.
1224		Any change to this variable will be reverted at the
1225		next reset.
1226
1227- Real-Time Clock:
1228
1229		When CONFIG_CMD_DATE is selected, the type of the RTC
1230		has to be selected, too. Define exactly one of the
1231		following options:
1232
1233		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1234		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1235		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1236		CONFIG_RTC_MC146818	- use MC146818 RTC
1237		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1238		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1239		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1240		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1241		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1242		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1243		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1244		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1245		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1246					  RV3029 RTC.
1247
1248		Note that if the RTC uses I2C, then the I2C interface
1249		must also be configured. See I2C Support, below.
1250
1251- GPIO Support:
1252		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1253
1254		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1255		chip-ngpio pairs that tell the PCA953X driver the number of
1256		pins supported by a particular chip.
1257
1258		Note that if the GPIO device uses I2C, then the I2C interface
1259		must also be configured. See I2C Support, below.
1260
1261- I/O tracing:
1262		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1263		accesses and can checksum them or write a list of them out
1264		to memory. See the 'iotrace' command for details. This is
1265		useful for testing device drivers since it can confirm that
1266		the driver behaves the same way before and after a code
1267		change. Currently this is supported on sandbox and arm. To
1268		add support for your architecture, add '#include <iotrace.h>'
1269		to the bottom of arch/<arch>/include/asm/io.h and test.
1270
1271		Example output from the 'iotrace stats' command is below.
1272		Note that if the trace buffer is exhausted, the checksum will
1273		still continue to operate.
1274
1275			iotrace is enabled
1276			Start:  10000000	(buffer start address)
1277			Size:   00010000	(buffer size)
1278			Offset: 00000120	(current buffer offset)
1279			Output: 10000120	(start + offset)
1280			Count:  00000018	(number of trace records)
1281			CRC32:  9526fb66	(CRC32 of all trace records)
1282
1283- Timestamp Support:
1284
1285		When CONFIG_TIMESTAMP is selected, the timestamp
1286		(date and time) of an image is printed by image
1287		commands like bootm or iminfo. This option is
1288		automatically enabled when you select CONFIG_CMD_DATE .
1289
1290- Partition Labels (disklabels) Supported:
1291		Zero or more of the following:
1292		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1293		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1294				       Intel architecture, USB sticks, etc.
1295		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1296		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1297				       bootloader.  Note 2TB partition limit; see
1298				       disk/part_efi.c
1299		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1300
1301		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1302		CONFIG_CMD_SCSI) you must configure support for at
1303		least one non-MTD partition type as well.
1304
1305- IDE Reset method:
1306		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1307		board configurations files but used nowhere!
1308
1309		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1310		be performed by calling the function
1311			ide_set_reset(int reset)
1312		which has to be defined in a board specific file
1313
1314- ATAPI Support:
1315		CONFIG_ATAPI
1316
1317		Set this to enable ATAPI support.
1318
1319- LBA48 Support
1320		CONFIG_LBA48
1321
1322		Set this to enable support for disks larger than 137GB
1323		Also look at CONFIG_SYS_64BIT_LBA.
1324		Whithout these , LBA48 support uses 32bit variables and will 'only'
1325		support disks up to 2.1TB.
1326
1327		CONFIG_SYS_64BIT_LBA:
1328			When enabled, makes the IDE subsystem use 64bit sector addresses.
1329			Default is 32bit.
1330
1331- SCSI Support:
1332		At the moment only there is only support for the
1333		SYM53C8XX SCSI controller; define
1334		CONFIG_SCSI_SYM53C8XX to enable it.
1335
1336		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1337		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1338		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1339		maximum numbers of LUNs, SCSI ID's and target
1340		devices.
1341		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1342
1343		The environment variable 'scsidevs' is set to the number of
1344		SCSI devices found during the last scan.
1345
1346- NETWORK Support (PCI):
1347		CONFIG_E1000
1348		Support for Intel 8254x/8257x gigabit chips.
1349
1350		CONFIG_E1000_SPI
1351		Utility code for direct access to the SPI bus on Intel 8257x.
1352		This does not do anything useful unless you set at least one
1353		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1354
1355		CONFIG_E1000_SPI_GENERIC
1356		Allow generic access to the SPI bus on the Intel 8257x, for
1357		example with the "sspi" command.
1358
1359		CONFIG_CMD_E1000
1360		Management command for E1000 devices.  When used on devices
1361		with SPI support you can reprogram the EEPROM from U-Boot.
1362
1363		CONFIG_EEPRO100
1364		Support for Intel 82557/82559/82559ER chips.
1365		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1366		write routine for first time initialisation.
1367
1368		CONFIG_TULIP
1369		Support for Digital 2114x chips.
1370		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1371		modem chip initialisation (KS8761/QS6611).
1372
1373		CONFIG_NATSEMI
1374		Support for National dp83815 chips.
1375
1376		CONFIG_NS8382X
1377		Support for National dp8382[01] gigabit chips.
1378
1379- NETWORK Support (other):
1380
1381		CONFIG_DRIVER_AT91EMAC
1382		Support for AT91RM9200 EMAC.
1383
1384			CONFIG_RMII
1385			Define this to use reduced MII inteface
1386
1387			CONFIG_DRIVER_AT91EMAC_QUIET
1388			If this defined, the driver is quiet.
1389			The driver doen't show link status messages.
1390
1391		CONFIG_CALXEDA_XGMAC
1392		Support for the Calxeda XGMAC device
1393
1394		CONFIG_LAN91C96
1395		Support for SMSC's LAN91C96 chips.
1396
1397			CONFIG_LAN91C96_BASE
1398			Define this to hold the physical address
1399			of the LAN91C96's I/O space
1400
1401			CONFIG_LAN91C96_USE_32_BIT
1402			Define this to enable 32 bit addressing
1403
1404		CONFIG_SMC91111
1405		Support for SMSC's LAN91C111 chip
1406
1407			CONFIG_SMC91111_BASE
1408			Define this to hold the physical address
1409			of the device (I/O space)
1410
1411			CONFIG_SMC_USE_32_BIT
1412			Define this if data bus is 32 bits
1413
1414			CONFIG_SMC_USE_IOFUNCS
1415			Define this to use i/o functions instead of macros
1416			(some hardware wont work with macros)
1417
1418		CONFIG_DRIVER_TI_EMAC
1419		Support for davinci emac
1420
1421			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1422			Define this if you have more then 3 PHYs.
1423
1424		CONFIG_FTGMAC100
1425		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1426
1427			CONFIG_FTGMAC100_EGIGA
1428			Define this to use GE link update with gigabit PHY.
1429			Define this if FTGMAC100 is connected to gigabit PHY.
1430			If your system has 10/100 PHY only, it might not occur
1431			wrong behavior. Because PHY usually return timeout or
1432			useless data when polling gigabit status and gigabit
1433			control registers. This behavior won't affect the
1434			correctnessof 10/100 link speed update.
1435
1436		CONFIG_SMC911X
1437		Support for SMSC's LAN911x and LAN921x chips
1438
1439			CONFIG_SMC911X_BASE
1440			Define this to hold the physical address
1441			of the device (I/O space)
1442
1443			CONFIG_SMC911X_32_BIT
1444			Define this if data bus is 32 bits
1445
1446			CONFIG_SMC911X_16_BIT
1447			Define this if data bus is 16 bits. If your processor
1448			automatically converts one 32 bit word to two 16 bit
1449			words you may also try CONFIG_SMC911X_32_BIT.
1450
1451		CONFIG_SH_ETHER
1452		Support for Renesas on-chip Ethernet controller
1453
1454			CONFIG_SH_ETHER_USE_PORT
1455			Define the number of ports to be used
1456
1457			CONFIG_SH_ETHER_PHY_ADDR
1458			Define the ETH PHY's address
1459
1460			CONFIG_SH_ETHER_CACHE_WRITEBACK
1461			If this option is set, the driver enables cache flush.
1462
1463- PWM Support:
1464		CONFIG_PWM_IMX
1465		Support for PWM modul on the imx6.
1466
1467- TPM Support:
1468		CONFIG_TPM
1469		Support TPM devices.
1470
1471		CONFIG_TPM_TIS_INFINEON
1472		Support for Infineon i2c bus TPM devices. Only one device
1473		per system is supported at this time.
1474
1475			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1476			Define the burst count bytes upper limit
1477
1478		CONFIG_TPM_ATMEL_TWI
1479		Support for Atmel TWI TPM device. Requires I2C support.
1480
1481		CONFIG_TPM_TIS_LPC
1482		Support for generic parallel port TPM devices. Only one device
1483		per system is supported at this time.
1484
1485			CONFIG_TPM_TIS_BASE_ADDRESS
1486			Base address where the generic TPM device is mapped
1487			to. Contemporary x86 systems usually map it at
1488			0xfed40000.
1489
1490		CONFIG_CMD_TPM
1491		Add tpm monitor functions.
1492		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1493		provides monitor access to authorized functions.
1494
1495		CONFIG_TPM
1496		Define this to enable the TPM support library which provides
1497		functional interfaces to some TPM commands.
1498		Requires support for a TPM device.
1499
1500		CONFIG_TPM_AUTH_SESSIONS
1501		Define this to enable authorized functions in the TPM library.
1502		Requires CONFIG_TPM and CONFIG_SHA1.
1503
1504- USB Support:
1505		At the moment only the UHCI host controller is
1506		supported (PIP405, MIP405, MPC5200); define
1507		CONFIG_USB_UHCI to enable it.
1508		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1509		and define CONFIG_USB_STORAGE to enable the USB
1510		storage devices.
1511		Note:
1512		Supported are USB Keyboards and USB Floppy drives
1513		(TEAC FD-05PUB).
1514		MPC5200 USB requires additional defines:
1515			CONFIG_USB_CLOCK
1516				for 528 MHz Clock: 0x0001bbbb
1517			CONFIG_PSC3_USB
1518				for USB on PSC3
1519			CONFIG_USB_CONFIG
1520				for differential drivers: 0x00001000
1521				for single ended drivers: 0x00005000
1522				for differential drivers on PSC3: 0x00000100
1523				for single ended drivers on PSC3: 0x00004100
1524			CONFIG_SYS_USB_EVENT_POLL
1525				May be defined to allow interrupt polling
1526				instead of using asynchronous interrupts
1527
1528		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1529		txfilltuning field in the EHCI controller on reset.
1530
1531		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1532		HW module registers.
1533
1534- USB Device:
1535		Define the below if you wish to use the USB console.
1536		Once firmware is rebuilt from a serial console issue the
1537		command "setenv stdin usbtty; setenv stdout usbtty" and
1538		attach your USB cable. The Unix command "dmesg" should print
1539		it has found a new device. The environment variable usbtty
1540		can be set to gserial or cdc_acm to enable your device to
1541		appear to a USB host as a Linux gserial device or a
1542		Common Device Class Abstract Control Model serial device.
1543		If you select usbtty = gserial you should be able to enumerate
1544		a Linux host by
1545		# modprobe usbserial vendor=0xVendorID product=0xProductID
1546		else if using cdc_acm, simply setting the environment
1547		variable usbtty to be cdc_acm should suffice. The following
1548		might be defined in YourBoardName.h
1549
1550			CONFIG_USB_DEVICE
1551			Define this to build a UDC device
1552
1553			CONFIG_USB_TTY
1554			Define this to have a tty type of device available to
1555			talk to the UDC device
1556
1557			CONFIG_USBD_HS
1558			Define this to enable the high speed support for usb
1559			device and usbtty. If this feature is enabled, a routine
1560			int is_usbd_high_speed(void)
1561			also needs to be defined by the driver to dynamically poll
1562			whether the enumeration has succeded at high speed or full
1563			speed.
1564
1565			CONFIG_SYS_CONSOLE_IS_IN_ENV
1566			Define this if you want stdin, stdout &/or stderr to
1567			be set to usbtty.
1568
1569			mpc8xx:
1570				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1571				Derive USB clock from external clock "blah"
1572				- CONFIG_SYS_USB_EXTC_CLK 0x02
1573
1574				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1575				Derive USB clock from brgclk
1576				- CONFIG_SYS_USB_BRG_CLK 0x04
1577
1578		If you have a USB-IF assigned VendorID then you may wish to
1579		define your own vendor specific values either in BoardName.h
1580		or directly in usbd_vendor_info.h. If you don't define
1581		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1582		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1583		should pretend to be a Linux device to it's target host.
1584
1585			CONFIG_USBD_MANUFACTURER
1586			Define this string as the name of your company for
1587			- CONFIG_USBD_MANUFACTURER "my company"
1588
1589			CONFIG_USBD_PRODUCT_NAME
1590			Define this string as the name of your product
1591			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1592
1593			CONFIG_USBD_VENDORID
1594			Define this as your assigned Vendor ID from the USB
1595			Implementors Forum. This *must* be a genuine Vendor ID
1596			to avoid polluting the USB namespace.
1597			- CONFIG_USBD_VENDORID 0xFFFF
1598
1599			CONFIG_USBD_PRODUCTID
1600			Define this as the unique Product ID
1601			for your device
1602			- CONFIG_USBD_PRODUCTID 0xFFFF
1603
1604- ULPI Layer Support:
1605		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1606		the generic ULPI layer. The generic layer accesses the ULPI PHY
1607		via the platform viewport, so you need both the genric layer and
1608		the viewport enabled. Currently only Chipidea/ARC based
1609		viewport is supported.
1610		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1611		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1612		If your ULPI phy needs a different reference clock than the
1613		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1614		the appropriate value in Hz.
1615
1616- MMC Support:
1617		The MMC controller on the Intel PXA is supported. To
1618		enable this define CONFIG_MMC. The MMC can be
1619		accessed from the boot prompt by mapping the device
1620		to physical memory similar to flash. Command line is
1621		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1622		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1623
1624		CONFIG_SH_MMCIF
1625		Support for Renesas on-chip MMCIF controller
1626
1627			CONFIG_SH_MMCIF_ADDR
1628			Define the base address of MMCIF registers
1629
1630			CONFIG_SH_MMCIF_CLK
1631			Define the clock frequency for MMCIF
1632
1633		CONFIG_GENERIC_MMC
1634		Enable the generic MMC driver
1635
1636		CONFIG_SUPPORT_EMMC_BOOT
1637		Enable some additional features of the eMMC boot partitions.
1638
1639		CONFIG_SUPPORT_EMMC_RPMB
1640		Enable the commands for reading, writing and programming the
1641		key for the Replay Protection Memory Block partition in eMMC.
1642
1643- USB Device Firmware Update (DFU) class support:
1644		CONFIG_USB_FUNCTION_DFU
1645		This enables the USB portion of the DFU USB class
1646
1647		CONFIG_CMD_DFU
1648		This enables the command "dfu" which is used to have
1649		U-Boot create a DFU class device via USB.  This command
1650		requires that the "dfu_alt_info" environment variable be
1651		set and define the alt settings to expose to the host.
1652
1653		CONFIG_DFU_MMC
1654		This enables support for exposing (e)MMC devices via DFU.
1655
1656		CONFIG_DFU_NAND
1657		This enables support for exposing NAND devices via DFU.
1658
1659		CONFIG_DFU_RAM
1660		This enables support for exposing RAM via DFU.
1661		Note: DFU spec refer to non-volatile memory usage, but
1662		allow usages beyond the scope of spec - here RAM usage,
1663		one that would help mostly the developer.
1664
1665		CONFIG_SYS_DFU_DATA_BUF_SIZE
1666		Dfu transfer uses a buffer before writing data to the
1667		raw storage device. Make the size (in bytes) of this buffer
1668		configurable. The size of this buffer is also configurable
1669		through the "dfu_bufsiz" environment variable.
1670
1671		CONFIG_SYS_DFU_MAX_FILE_SIZE
1672		When updating files rather than the raw storage device,
1673		we use a static buffer to copy the file into and then write
1674		the buffer once we've been given the whole file.  Define
1675		this to the maximum filesize (in bytes) for the buffer.
1676		Default is 4 MiB if undefined.
1677
1678		DFU_DEFAULT_POLL_TIMEOUT
1679		Poll timeout [ms], is the timeout a device can send to the
1680		host. The host must wait for this timeout before sending
1681		a subsequent DFU_GET_STATUS request to the device.
1682
1683		DFU_MANIFEST_POLL_TIMEOUT
1684		Poll timeout [ms], which the device sends to the host when
1685		entering dfuMANIFEST state. Host waits this timeout, before
1686		sending again an USB request to the device.
1687
1688- USB Device Android Fastboot support:
1689		CONFIG_USB_FUNCTION_FASTBOOT
1690		This enables the USB part of the fastboot gadget
1691
1692		CONFIG_CMD_FASTBOOT
1693		This enables the command "fastboot" which enables the Android
1694		fastboot mode for the platform's USB device. Fastboot is a USB
1695		protocol for downloading images, flashing and device control
1696		used on Android devices.
1697		See doc/README.android-fastboot for more information.
1698
1699		CONFIG_ANDROID_BOOT_IMAGE
1700		This enables support for booting images which use the Android
1701		image format header.
1702
1703		CONFIG_FASTBOOT_BUF_ADDR
1704		The fastboot protocol requires a large memory buffer for
1705		downloads. Define this to the starting RAM address to use for
1706		downloaded images.
1707
1708		CONFIG_FASTBOOT_BUF_SIZE
1709		The fastboot protocol requires a large memory buffer for
1710		downloads. This buffer should be as large as possible for a
1711		platform. Define this to the size available RAM for fastboot.
1712
1713		CONFIG_FASTBOOT_FLASH
1714		The fastboot protocol includes a "flash" command for writing
1715		the downloaded image to a non-volatile storage device. Define
1716		this to enable the "fastboot flash" command.
1717
1718		CONFIG_FASTBOOT_FLASH_MMC_DEV
1719		The fastboot "flash" command requires additional information
1720		regarding the non-volatile storage device. Define this to
1721		the eMMC device that fastboot should use to store the image.
1722
1723		CONFIG_FASTBOOT_GPT_NAME
1724		The fastboot "flash" command supports writing the downloaded
1725		image to the Protective MBR and the Primary GUID Partition
1726		Table. (Additionally, this downloaded image is post-processed
1727		to generate and write the Backup GUID Partition Table.)
1728		This occurs when the specified "partition name" on the
1729		"fastboot flash" command line matches this value.
1730		Default is GPT_ENTRY_NAME (currently "gpt") if undefined.
1731
1732- Journaling Flash filesystem support:
1733		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1734		CONFIG_JFFS2_NAND_DEV
1735		Define these for a default partition on a NAND device
1736
1737		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1738		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1739		Define these for a default partition on a NOR device
1740
1741		CONFIG_SYS_JFFS_CUSTOM_PART
1742		Define this to create an own partition. You have to provide a
1743		function struct part_info* jffs2_part_info(int part_num)
1744
1745		If you define only one JFFS2 partition you may also want to
1746		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1747		to disable the command chpart. This is the default when you
1748		have not defined a custom partition
1749
1750- FAT(File Allocation Table) filesystem write function support:
1751		CONFIG_FAT_WRITE
1752
1753		Define this to enable support for saving memory data as a
1754		file in FAT formatted partition.
1755
1756		This will also enable the command "fatwrite" enabling the
1757		user to write files to FAT.
1758
1759CBFS (Coreboot Filesystem) support
1760		CONFIG_CMD_CBFS
1761
1762		Define this to enable support for reading from a Coreboot
1763		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1764		and cbfsload.
1765
1766- FAT(File Allocation Table) filesystem cluster size:
1767		CONFIG_FS_FAT_MAX_CLUSTSIZE
1768
1769		Define the max cluster size for fat operations else
1770		a default value of 65536 will be defined.
1771
1772- Keyboard Support:
1773		See Kconfig help for available keyboard drivers.
1774
1775		CONFIG_KEYBOARD
1776
1777		Define this to enable a custom keyboard support.
1778		This simply calls drv_keyboard_init() which must be
1779		defined in your board-specific files. This option is deprecated
1780		and is only used by novena. For new boards, use driver model
1781		instead.
1782
1783- Video support:
1784		CONFIG_VIDEO
1785
1786		Define this to enable video support (for output to
1787		video).
1788
1789		CONFIG_VIDEO_CT69000
1790
1791		Enable Chips & Technologies 69000 Video chip
1792
1793		CONFIG_VIDEO_SMI_LYNXEM
1794		Enable Silicon Motion SMI 712/710/810 Video chip. The
1795		video output is selected via environment 'videoout'
1796		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1797		assumed.
1798
1799		For the CT69000 and SMI_LYNXEM drivers, videomode is
1800		selected via environment 'videomode'. Two different ways
1801		are possible:
1802		- "videomode=num"   'num' is a standard LiLo mode numbers.
1803		Following standard modes are supported	(* is default):
1804
1805		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1806		-------------+---------------------------------------------
1807		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1808		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1809		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1810		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1811		-------------+---------------------------------------------
1812		(i.e. setenv videomode 317; saveenv; reset;)
1813
1814		- "videomode=bootargs" all the video parameters are parsed
1815		from the bootargs. (See drivers/video/videomodes.c)
1816
1817
1818		CONFIG_VIDEO_SED13806
1819		Enable Epson SED13806 driver. This driver supports 8bpp
1820		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1821		or CONFIG_VIDEO_SED13806_16BPP
1822
1823		CONFIG_FSL_DIU_FB
1824		Enable the Freescale DIU video driver.	Reference boards for
1825		SOCs that have a DIU should define this macro to enable DIU
1826		support, and should also define these other macros:
1827
1828			CONFIG_SYS_DIU_ADDR
1829			CONFIG_VIDEO
1830			CONFIG_CMD_BMP
1831			CONFIG_CFB_CONSOLE
1832			CONFIG_VIDEO_SW_CURSOR
1833			CONFIG_VGA_AS_SINGLE_DEVICE
1834			CONFIG_VIDEO_LOGO
1835			CONFIG_VIDEO_BMP_LOGO
1836
1837		The DIU driver will look for the 'video-mode' environment
1838		variable, and if defined, enable the DIU as a console during
1839		boot.  See the documentation file README.video for a
1840		description of this variable.
1841
1842- LCD Support:	CONFIG_LCD
1843
1844		Define this to enable LCD support (for output to LCD
1845		display); also select one of the supported displays
1846		by defining one of these:
1847
1848		CONFIG_ATMEL_LCD:
1849
1850			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1851
1852		CONFIG_NEC_NL6448AC33:
1853
1854			NEC NL6448AC33-18. Active, color, single scan.
1855
1856		CONFIG_NEC_NL6448BC20
1857
1858			NEC NL6448BC20-08. 6.5", 640x480.
1859			Active, color, single scan.
1860
1861		CONFIG_NEC_NL6448BC33_54
1862
1863			NEC NL6448BC33-54. 10.4", 640x480.
1864			Active, color, single scan.
1865
1866		CONFIG_SHARP_16x9
1867
1868			Sharp 320x240. Active, color, single scan.
1869			It isn't 16x9, and I am not sure what it is.
1870
1871		CONFIG_SHARP_LQ64D341
1872
1873			Sharp LQ64D341 display, 640x480.
1874			Active, color, single scan.
1875
1876		CONFIG_HLD1045
1877
1878			HLD1045 display, 640x480.
1879			Active, color, single scan.
1880
1881		CONFIG_OPTREX_BW
1882
1883			Optrex	 CBL50840-2 NF-FW 99 22 M5
1884			or
1885			Hitachi	 LMG6912RPFC-00T
1886			or
1887			Hitachi	 SP14Q002
1888
1889			320x240. Black & white.
1890
1891		Normally display is black on white background; define
1892		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1893
1894		CONFIG_LCD_ALIGNMENT
1895
1896		Normally the LCD is page-aligned (typically 4KB). If this is
1897		defined then the LCD will be aligned to this value instead.
1898		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1899		here, since it is cheaper to change data cache settings on
1900		a per-section basis.
1901
1902		CONFIG_CONSOLE_SCROLL_LINES
1903
1904		When the console need to be scrolled, this is the number of
1905		lines to scroll by. It defaults to 1. Increasing this makes
1906		the console jump but can help speed up operation when scrolling
1907		is slow.
1908
1909		CONFIG_LCD_ROTATION
1910
1911		Sometimes, for example if the display is mounted in portrait
1912		mode or even if it's mounted landscape but rotated by 180degree,
1913		we need to rotate our content of the display relative to the
1914		framebuffer, so that user can read the messages which are
1915		printed out.
1916		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1917		initialized with a given rotation from "vl_rot" out of
1918		"vidinfo_t" which is provided by the board specific code.
1919		The value for vl_rot is coded as following (matching to
1920		fbcon=rotate:<n> linux-kernel commandline):
1921		0 = no rotation respectively 0 degree
1922		1 = 90 degree rotation
1923		2 = 180 degree rotation
1924		3 = 270 degree rotation
1925
1926		If CONFIG_LCD_ROTATION is not defined, the console will be
1927		initialized with 0degree rotation.
1928
1929		CONFIG_LCD_BMP_RLE8
1930
1931		Support drawing of RLE8-compressed bitmaps on the LCD.
1932
1933		CONFIG_I2C_EDID
1934
1935		Enables an 'i2c edid' command which can read EDID
1936		information over I2C from an attached LCD display.
1937
1938- Splash Screen Support: CONFIG_SPLASH_SCREEN
1939
1940		If this option is set, the environment is checked for
1941		a variable "splashimage". If found, the usual display
1942		of logo, copyright and system information on the LCD
1943		is suppressed and the BMP image at the address
1944		specified in "splashimage" is loaded instead. The
1945		console is redirected to the "nulldev", too. This
1946		allows for a "silent" boot where a splash screen is
1947		loaded very quickly after power-on.
1948
1949		CONFIG_SPLASHIMAGE_GUARD
1950
1951		If this option is set, then U-Boot will prevent the environment
1952		variable "splashimage" from being set to a problematic address
1953		(see README.displaying-bmps).
1954		This option is useful for targets where, due to alignment
1955		restrictions, an improperly aligned BMP image will cause a data
1956		abort. If you think you will not have problems with unaligned
1957		accesses (for example because your toolchain prevents them)
1958		there is no need to set this option.
1959
1960		CONFIG_SPLASH_SCREEN_ALIGN
1961
1962		If this option is set the splash image can be freely positioned
1963		on the screen. Environment variable "splashpos" specifies the
1964		position as "x,y". If a positive number is given it is used as
1965		number of pixel from left/top. If a negative number is given it
1966		is used as number of pixel from right/bottom. You can also
1967		specify 'm' for centering the image.
1968
1969		Example:
1970		setenv splashpos m,m
1971			=> image at center of screen
1972
1973		setenv splashpos 30,20
1974			=> image at x = 30 and y = 20
1975
1976		setenv splashpos -10,m
1977			=> vertically centered image
1978			   at x = dspWidth - bmpWidth - 9
1979
1980- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1981
1982		If this option is set, additionally to standard BMP
1983		images, gzipped BMP images can be displayed via the
1984		splashscreen support or the bmp command.
1985
1986- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1987
1988		If this option is set, 8-bit RLE compressed BMP images
1989		can be displayed via the splashscreen support or the
1990		bmp command.
1991
1992- Do compressing for memory range:
1993		CONFIG_CMD_ZIP
1994
1995		If this option is set, it would use zlib deflate method
1996		to compress the specified memory at its best effort.
1997
1998- Compression support:
1999		CONFIG_GZIP
2000
2001		Enabled by default to support gzip compressed images.
2002
2003		CONFIG_BZIP2
2004
2005		If this option is set, support for bzip2 compressed
2006		images is included. If not, only uncompressed and gzip
2007		compressed images are supported.
2008
2009		NOTE: the bzip2 algorithm requires a lot of RAM, so
2010		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
2011		be at least 4MB.
2012
2013		CONFIG_LZMA
2014
2015		If this option is set, support for lzma compressed
2016		images is included.
2017
2018		Note: The LZMA algorithm adds between 2 and 4KB of code and it
2019		requires an amount of dynamic memory that is given by the
2020		formula:
2021
2022			(1846 + 768 << (lc + lp)) * sizeof(uint16)
2023
2024		Where lc and lp stand for, respectively, Literal context bits
2025		and Literal pos bits.
2026
2027		This value is upper-bounded by 14MB in the worst case. Anyway,
2028		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
2029		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
2030		a very small buffer.
2031
2032		Use the lzmainfo tool to determinate the lc and lp values and
2033		then calculate the amount of needed dynamic memory (ensuring
2034		the appropriate CONFIG_SYS_MALLOC_LEN value).
2035
2036		CONFIG_LZO
2037
2038		If this option is set, support for LZO compressed images
2039		is included.
2040
2041- MII/PHY support:
2042		CONFIG_PHY_ADDR
2043
2044		The address of PHY on MII bus.
2045
2046		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
2047
2048		The clock frequency of the MII bus
2049
2050		CONFIG_PHY_GIGE
2051
2052		If this option is set, support for speed/duplex
2053		detection of gigabit PHY is included.
2054
2055		CONFIG_PHY_RESET_DELAY
2056
2057		Some PHY like Intel LXT971A need extra delay after
2058		reset before any MII register access is possible.
2059		For such PHY, set this option to the usec delay
2060		required. (minimum 300usec for LXT971A)
2061
2062		CONFIG_PHY_CMD_DELAY (ppc4xx)
2063
2064		Some PHY like Intel LXT971A need extra delay after
2065		command issued before MII status register can be read
2066
2067- IP address:
2068		CONFIG_IPADDR
2069
2070		Define a default value for the IP address to use for
2071		the default Ethernet interface, in case this is not
2072		determined through e.g. bootp.
2073		(Environment variable "ipaddr")
2074
2075- Server IP address:
2076		CONFIG_SERVERIP
2077
2078		Defines a default value for the IP address of a TFTP
2079		server to contact when using the "tftboot" command.
2080		(Environment variable "serverip")
2081
2082		CONFIG_KEEP_SERVERADDR
2083
2084		Keeps the server's MAC address, in the env 'serveraddr'
2085		for passing to bootargs (like Linux's netconsole option)
2086
2087- Gateway IP address:
2088		CONFIG_GATEWAYIP
2089
2090		Defines a default value for the IP address of the
2091		default router where packets to other networks are
2092		sent to.
2093		(Environment variable "gatewayip")
2094
2095- Subnet mask:
2096		CONFIG_NETMASK
2097
2098		Defines a default value for the subnet mask (or
2099		routing prefix) which is used to determine if an IP
2100		address belongs to the local subnet or needs to be
2101		forwarded through a router.
2102		(Environment variable "netmask")
2103
2104- Multicast TFTP Mode:
2105		CONFIG_MCAST_TFTP
2106
2107		Defines whether you want to support multicast TFTP as per
2108		rfc-2090; for example to work with atftp.  Lets lots of targets
2109		tftp down the same boot image concurrently.  Note: the Ethernet
2110		driver in use must provide a function: mcast() to join/leave a
2111		multicast group.
2112
2113- BOOTP Recovery Mode:
2114		CONFIG_BOOTP_RANDOM_DELAY
2115
2116		If you have many targets in a network that try to
2117		boot using BOOTP, you may want to avoid that all
2118		systems send out BOOTP requests at precisely the same
2119		moment (which would happen for instance at recovery
2120		from a power failure, when all systems will try to
2121		boot, thus flooding the BOOTP server. Defining
2122		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2123		inserted before sending out BOOTP requests. The
2124		following delays are inserted then:
2125
2126		1st BOOTP request:	delay 0 ... 1 sec
2127		2nd BOOTP request:	delay 0 ... 2 sec
2128		3rd BOOTP request:	delay 0 ... 4 sec
2129		4th and following
2130		BOOTP requests:		delay 0 ... 8 sec
2131
2132		CONFIG_BOOTP_ID_CACHE_SIZE
2133
2134		BOOTP packets are uniquely identified using a 32-bit ID. The
2135		server will copy the ID from client requests to responses and
2136		U-Boot will use this to determine if it is the destination of
2137		an incoming response. Some servers will check that addresses
2138		aren't in use before handing them out (usually using an ARP
2139		ping) and therefore take up to a few hundred milliseconds to
2140		respond. Network congestion may also influence the time it
2141		takes for a response to make it back to the client. If that
2142		time is too long, U-Boot will retransmit requests. In order
2143		to allow earlier responses to still be accepted after these
2144		retransmissions, U-Boot's BOOTP client keeps a small cache of
2145		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2146		cache. The default is to keep IDs for up to four outstanding
2147		requests. Increasing this will allow U-Boot to accept offers
2148		from a BOOTP client in networks with unusually high latency.
2149
2150- DHCP Advanced Options:
2151		You can fine tune the DHCP functionality by defining
2152		CONFIG_BOOTP_* symbols:
2153
2154		CONFIG_BOOTP_SUBNETMASK
2155		CONFIG_BOOTP_GATEWAY
2156		CONFIG_BOOTP_HOSTNAME
2157		CONFIG_BOOTP_NISDOMAIN
2158		CONFIG_BOOTP_BOOTPATH
2159		CONFIG_BOOTP_BOOTFILESIZE
2160		CONFIG_BOOTP_DNS
2161		CONFIG_BOOTP_DNS2
2162		CONFIG_BOOTP_SEND_HOSTNAME
2163		CONFIG_BOOTP_NTPSERVER
2164		CONFIG_BOOTP_TIMEOFFSET
2165		CONFIG_BOOTP_VENDOREX
2166		CONFIG_BOOTP_MAY_FAIL
2167
2168		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2169		environment variable, not the BOOTP server.
2170
2171		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2172		after the configured retry count, the call will fail
2173		instead of starting over.  This can be used to fail over
2174		to Link-local IP address configuration if the DHCP server
2175		is not available.
2176
2177		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2178		serverip from a DHCP server, it is possible that more
2179		than one DNS serverip is offered to the client.
2180		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2181		serverip will be stored in the additional environment
2182		variable "dnsip2". The first DNS serverip is always
2183		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2184		is defined.
2185
2186		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2187		to do a dynamic update of a DNS server. To do this, they
2188		need the hostname of the DHCP requester.
2189		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2190		of the "hostname" environment variable is passed as
2191		option 12 to the DHCP server.
2192
2193		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2194
2195		A 32bit value in microseconds for a delay between
2196		receiving a "DHCP Offer" and sending the "DHCP Request".
2197		This fixes a problem with certain DHCP servers that don't
2198		respond 100% of the time to a "DHCP request". E.g. On an
2199		AT91RM9200 processor running at 180MHz, this delay needed
2200		to be *at least* 15,000 usec before a Windows Server 2003
2201		DHCP server would reply 100% of the time. I recommend at
2202		least 50,000 usec to be safe. The alternative is to hope
2203		that one of the retries will be successful but note that
2204		the DHCP timeout and retry process takes a longer than
2205		this delay.
2206
2207 - Link-local IP address negotiation:
2208		Negotiate with other link-local clients on the local network
2209		for an address that doesn't require explicit configuration.
2210		This is especially useful if a DHCP server cannot be guaranteed
2211		to exist in all environments that the device must operate.
2212
2213		See doc/README.link-local for more information.
2214
2215 - CDP Options:
2216		CONFIG_CDP_DEVICE_ID
2217
2218		The device id used in CDP trigger frames.
2219
2220		CONFIG_CDP_DEVICE_ID_PREFIX
2221
2222		A two character string which is prefixed to the MAC address
2223		of the device.
2224
2225		CONFIG_CDP_PORT_ID
2226
2227		A printf format string which contains the ascii name of
2228		the port. Normally is set to "eth%d" which sets
2229		eth0 for the first Ethernet, eth1 for the second etc.
2230
2231		CONFIG_CDP_CAPABILITIES
2232
2233		A 32bit integer which indicates the device capabilities;
2234		0x00000010 for a normal host which does not forwards.
2235
2236		CONFIG_CDP_VERSION
2237
2238		An ascii string containing the version of the software.
2239
2240		CONFIG_CDP_PLATFORM
2241
2242		An ascii string containing the name of the platform.
2243
2244		CONFIG_CDP_TRIGGER
2245
2246		A 32bit integer sent on the trigger.
2247
2248		CONFIG_CDP_POWER_CONSUMPTION
2249
2250		A 16bit integer containing the power consumption of the
2251		device in .1 of milliwatts.
2252
2253		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2254
2255		A byte containing the id of the VLAN.
2256
2257- Status LED:	CONFIG_STATUS_LED
2258
2259		Several configurations allow to display the current
2260		status using a LED. For instance, the LED will blink
2261		fast while running U-Boot code, stop blinking as
2262		soon as a reply to a BOOTP request was received, and
2263		start blinking slow once the Linux kernel is running
2264		(supported by a status LED driver in the Linux
2265		kernel). Defining CONFIG_STATUS_LED enables this
2266		feature in U-Boot.
2267
2268		Additional options:
2269
2270		CONFIG_GPIO_LED
2271		The status LED can be connected to a GPIO pin.
2272		In such cases, the gpio_led driver can be used as a
2273		status LED backend implementation. Define CONFIG_GPIO_LED
2274		to include the gpio_led driver in the U-Boot binary.
2275
2276		CONFIG_GPIO_LED_INVERTED_TABLE
2277		Some GPIO connected LEDs may have inverted polarity in which
2278		case the GPIO high value corresponds to LED off state and
2279		GPIO low value corresponds to LED on state.
2280		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2281		with a list of GPIO LEDs that have inverted polarity.
2282
2283- CAN Support:	CONFIG_CAN_DRIVER
2284
2285		Defining CONFIG_CAN_DRIVER enables CAN driver support
2286		on those systems that support this (optional)
2287		feature, like the TQM8xxL modules.
2288
2289- I2C Support:	CONFIG_SYS_I2C
2290
2291		This enable the NEW i2c subsystem, and will allow you to use
2292		i2c commands at the u-boot command line (as long as you set
2293		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2294		based realtime clock chips or other i2c devices. See
2295		common/cmd_i2c.c for a description of the command line
2296		interface.
2297
2298		ported i2c driver to the new framework:
2299		- drivers/i2c/soft_i2c.c:
2300		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2301		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2302		    for defining speed and slave address
2303		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2304		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2305		    for defining speed and slave address
2306		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2307		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2308		    for defining speed and slave address
2309		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2310		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2311		    for defining speed and slave address
2312
2313		- drivers/i2c/fsl_i2c.c:
2314		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2315		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2316		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2317		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2318		    bus.
2319		  - If your board supports a second fsl i2c bus, define
2320		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2321		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2322		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2323		    second bus.
2324
2325		- drivers/i2c/tegra_i2c.c:
2326		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2327		  - This driver adds 4 i2c buses with a fix speed from
2328		    100000 and the slave addr 0!
2329
2330		- drivers/i2c/ppc4xx_i2c.c
2331		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2332		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2333		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2334
2335		- drivers/i2c/i2c_mxc.c
2336		  - activate this driver with CONFIG_SYS_I2C_MXC
2337		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2338		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2339		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2340		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2341		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2342		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2343		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2344		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2345		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2346		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2347		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2348		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2349		If those defines are not set, default value is 100000
2350		for speed, and 0 for slave.
2351
2352		- drivers/i2c/rcar_i2c.c:
2353		  - activate this driver with CONFIG_SYS_I2C_RCAR
2354		  - This driver adds 4 i2c buses
2355
2356		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2357		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2358		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2359		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2360		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2361		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2362		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2363		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2364		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2365
2366		- drivers/i2c/sh_i2c.c:
2367		  - activate this driver with CONFIG_SYS_I2C_SH
2368		  - This driver adds from 2 to 5 i2c buses
2369
2370		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2371		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2372		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2373		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2374		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2375		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2376		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2377		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2378		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2379		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2380		  - CONFIG_SYS_I2C_SH_BASE5 for setting the register channel 5
2381		  - CONFIG_SYS_I2C_SH_SPEED5 for for the speed channel 5
2382		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2383
2384		- drivers/i2c/omap24xx_i2c.c
2385		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2386		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2387		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2388		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2389		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2390		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2391		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2392		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2393		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2394		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2395		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2396
2397		- drivers/i2c/zynq_i2c.c
2398		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2399		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2400		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2401
2402		- drivers/i2c/s3c24x0_i2c.c:
2403		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2404		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2405		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2406		    with a fix speed from 100000 and the slave addr 0!
2407
2408		- drivers/i2c/ihs_i2c.c
2409		  - activate this driver with CONFIG_SYS_I2C_IHS
2410		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2411		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2412		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2413		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2414		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2415		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2416		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2417		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2418		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2419		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2420		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2421		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2422		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2423		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2424		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2425		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2426		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2427		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2428		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2429		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2430		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2431
2432		additional defines:
2433
2434		CONFIG_SYS_NUM_I2C_BUSES
2435		Hold the number of i2c buses you want to use. If you
2436		don't use/have i2c muxes on your i2c bus, this
2437		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2438		omit this define.
2439
2440		CONFIG_SYS_I2C_DIRECT_BUS
2441		define this, if you don't use i2c muxes on your hardware.
2442		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2443		omit this define.
2444
2445		CONFIG_SYS_I2C_MAX_HOPS
2446		define how many muxes are maximal consecutively connected
2447		on one i2c bus. If you not use i2c muxes, omit this
2448		define.
2449
2450		CONFIG_SYS_I2C_BUSES
2451		hold a list of buses you want to use, only used if
2452		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2453		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2454		CONFIG_SYS_NUM_I2C_BUSES = 9:
2455
2456		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2457					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2458					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2459					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2460					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2461					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2462					{1, {I2C_NULL_HOP}}, \
2463					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2464					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2465					}
2466
2467		which defines
2468			bus 0 on adapter 0 without a mux
2469			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2470			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2471			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2472			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2473			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2474			bus 6 on adapter 1 without a mux
2475			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2476			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2477
2478		If you do not have i2c muxes on your board, omit this define.
2479
2480- Legacy I2C Support:	CONFIG_HARD_I2C
2481
2482		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2483		provides the following compelling advantages:
2484
2485		- more than one i2c adapter is usable
2486		- approved multibus support
2487		- better i2c mux support
2488
2489		** Please consider updating your I2C driver now. **
2490
2491		These enable legacy I2C serial bus commands. Defining
2492		CONFIG_HARD_I2C will include the appropriate I2C driver
2493		for the selected CPU.
2494
2495		This will allow you to use i2c commands at the u-boot
2496		command line (as long as you set CONFIG_CMD_I2C in
2497		CONFIG_COMMANDS) and communicate with i2c based realtime
2498		clock chips. See common/cmd_i2c.c for a description of the
2499		command line interface.
2500
2501		CONFIG_HARD_I2C selects a hardware I2C controller.
2502
2503		There are several other quantities that must also be
2504		defined when you define CONFIG_HARD_I2C.
2505
2506		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2507		to be the frequency (in Hz) at which you wish your i2c bus
2508		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2509		the CPU's i2c node address).
2510
2511		Now, the u-boot i2c code for the mpc8xx
2512		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2513		and so its address should therefore be cleared to 0 (See,
2514		eg, MPC823e User's Manual p.16-473). So, set
2515		CONFIG_SYS_I2C_SLAVE to 0.
2516
2517		CONFIG_SYS_I2C_INIT_MPC5XXX
2518
2519		When a board is reset during an i2c bus transfer
2520		chips might think that the current transfer is still
2521		in progress.  Reset the slave devices by sending start
2522		commands until the slave device responds.
2523
2524		That's all that's required for CONFIG_HARD_I2C.
2525
2526		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2527		then the following macros need to be defined (examples are
2528		from include/configs/lwmon.h):
2529
2530		I2C_INIT
2531
2532		(Optional). Any commands necessary to enable the I2C
2533		controller or configure ports.
2534
2535		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2536
2537		I2C_PORT
2538
2539		(Only for MPC8260 CPU). The I/O port to use (the code
2540		assumes both bits are on the same port). Valid values
2541		are 0..3 for ports A..D.
2542
2543		I2C_ACTIVE
2544
2545		The code necessary to make the I2C data line active
2546		(driven).  If the data line is open collector, this
2547		define can be null.
2548
2549		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2550
2551		I2C_TRISTATE
2552
2553		The code necessary to make the I2C data line tri-stated
2554		(inactive).  If the data line is open collector, this
2555		define can be null.
2556
2557		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2558
2559		I2C_READ
2560
2561		Code that returns true if the I2C data line is high,
2562		false if it is low.
2563
2564		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2565
2566		I2C_SDA(bit)
2567
2568		If <bit> is true, sets the I2C data line high. If it
2569		is false, it clears it (low).
2570
2571		eg: #define I2C_SDA(bit) \
2572			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2573			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2574
2575		I2C_SCL(bit)
2576
2577		If <bit> is true, sets the I2C clock line high. If it
2578		is false, it clears it (low).
2579
2580		eg: #define I2C_SCL(bit) \
2581			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2582			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2583
2584		I2C_DELAY
2585
2586		This delay is invoked four times per clock cycle so this
2587		controls the rate of data transfer.  The data rate thus
2588		is 1 / (I2C_DELAY * 4). Often defined to be something
2589		like:
2590
2591		#define I2C_DELAY  udelay(2)
2592
2593		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2594
2595		If your arch supports the generic GPIO framework (asm/gpio.h),
2596		then you may alternatively define the two GPIOs that are to be
2597		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2598		have GPIO-based defaults assigned to them as appropriate.
2599
2600		You should define these to the GPIO value as given directly to
2601		the generic GPIO functions.
2602
2603		CONFIG_SYS_I2C_INIT_BOARD
2604
2605		When a board is reset during an i2c bus transfer
2606		chips might think that the current transfer is still
2607		in progress. On some boards it is possible to access
2608		the i2c SCLK line directly, either by using the
2609		processor pin as a GPIO or by having a second pin
2610		connected to the bus. If this option is defined a
2611		custom i2c_init_board() routine in boards/xxx/board.c
2612		is run early in the boot sequence.
2613
2614		CONFIG_SYS_I2C_BOARD_LATE_INIT
2615
2616		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2617		defined a custom i2c_board_late_init() routine in
2618		boards/xxx/board.c is run AFTER the operations in i2c_init()
2619		is completed. This callpoint can be used to unreset i2c bus
2620		using CPU i2c controller register accesses for CPUs whose i2c
2621		controller provide such a method. It is called at the end of
2622		i2c_init() to allow i2c_init operations to setup the i2c bus
2623		controller on the CPU (e.g. setting bus speed & slave address).
2624
2625		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2626
2627		This option enables configuration of bi_iic_fast[] flags
2628		in u-boot bd_info structure based on u-boot environment
2629		variable "i2cfast". (see also i2cfast)
2630
2631		CONFIG_I2C_MULTI_BUS
2632
2633		This option allows the use of multiple I2C buses, each of which
2634		must have a controller.	 At any point in time, only one bus is
2635		active.	 To switch to a different bus, use the 'i2c dev' command.
2636		Note that bus numbering is zero-based.
2637
2638		CONFIG_SYS_I2C_NOPROBES
2639
2640		This option specifies a list of I2C devices that will be skipped
2641		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2642		is set, specify a list of bus-device pairs.  Otherwise, specify
2643		a 1D array of device addresses
2644
2645		e.g.
2646			#undef	CONFIG_I2C_MULTI_BUS
2647			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2648
2649		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2650
2651			#define CONFIG_I2C_MULTI_BUS
2652			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2653
2654		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2655
2656		CONFIG_SYS_SPD_BUS_NUM
2657
2658		If defined, then this indicates the I2C bus number for DDR SPD.
2659		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2660
2661		CONFIG_SYS_RTC_BUS_NUM
2662
2663		If defined, then this indicates the I2C bus number for the RTC.
2664		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2665
2666		CONFIG_SYS_DTT_BUS_NUM
2667
2668		If defined, then this indicates the I2C bus number for the DTT.
2669		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2670
2671		CONFIG_SYS_I2C_DTT_ADDR:
2672
2673		If defined, specifies the I2C address of the DTT device.
2674		If not defined, then U-Boot uses predefined value for
2675		specified DTT device.
2676
2677		CONFIG_SOFT_I2C_READ_REPEATED_START
2678
2679		defining this will force the i2c_read() function in
2680		the soft_i2c driver to perform an I2C repeated start
2681		between writing the address pointer and reading the
2682		data.  If this define is omitted the default behaviour
2683		of doing a stop-start sequence will be used.  Most I2C
2684		devices can use either method, but some require one or
2685		the other.
2686
2687- SPI Support:	CONFIG_SPI
2688
2689		Enables SPI driver (so far only tested with
2690		SPI EEPROM, also an instance works with Crystal A/D and
2691		D/As on the SACSng board)
2692
2693		CONFIG_SH_SPI
2694
2695		Enables the driver for SPI controller on SuperH. Currently
2696		only SH7757 is supported.
2697
2698		CONFIG_SOFT_SPI
2699
2700		Enables a software (bit-bang) SPI driver rather than
2701		using hardware support. This is a general purpose
2702		driver that only requires three general I/O port pins
2703		(two outputs, one input) to function. If this is
2704		defined, the board configuration must define several
2705		SPI configuration items (port pins to use, etc). For
2706		an example, see include/configs/sacsng.h.
2707
2708		CONFIG_HARD_SPI
2709
2710		Enables a hardware SPI driver for general-purpose reads
2711		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2712		must define a list of chip-select function pointers.
2713		Currently supported on some MPC8xxx processors.	 For an
2714		example, see include/configs/mpc8349emds.h.
2715
2716		CONFIG_MXC_SPI
2717
2718		Enables the driver for the SPI controllers on i.MX and MXC
2719		SoCs. Currently i.MX31/35/51 are supported.
2720
2721		CONFIG_SYS_SPI_MXC_WAIT
2722		Timeout for waiting until spi transfer completed.
2723		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2724
2725- FPGA Support: CONFIG_FPGA
2726
2727		Enables FPGA subsystem.
2728
2729		CONFIG_FPGA_<vendor>
2730
2731		Enables support for specific chip vendors.
2732		(ALTERA, XILINX)
2733
2734		CONFIG_FPGA_<family>
2735
2736		Enables support for FPGA family.
2737		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2738
2739		CONFIG_FPGA_COUNT
2740
2741		Specify the number of FPGA devices to support.
2742
2743		CONFIG_CMD_FPGA_LOADMK
2744
2745		Enable support for fpga loadmk command
2746
2747		CONFIG_CMD_FPGA_LOADP
2748
2749		Enable support for fpga loadp command - load partial bitstream
2750
2751		CONFIG_CMD_FPGA_LOADBP
2752
2753		Enable support for fpga loadbp command - load partial bitstream
2754		(Xilinx only)
2755
2756		CONFIG_SYS_FPGA_PROG_FEEDBACK
2757
2758		Enable printing of hash marks during FPGA configuration.
2759
2760		CONFIG_SYS_FPGA_CHECK_BUSY
2761
2762		Enable checks on FPGA configuration interface busy
2763		status by the configuration function. This option
2764		will require a board or device specific function to
2765		be written.
2766
2767		CONFIG_FPGA_DELAY
2768
2769		If defined, a function that provides delays in the FPGA
2770		configuration driver.
2771
2772		CONFIG_SYS_FPGA_CHECK_CTRLC
2773		Allow Control-C to interrupt FPGA configuration
2774
2775		CONFIG_SYS_FPGA_CHECK_ERROR
2776
2777		Check for configuration errors during FPGA bitfile
2778		loading. For example, abort during Virtex II
2779		configuration if the INIT_B line goes low (which
2780		indicated a CRC error).
2781
2782		CONFIG_SYS_FPGA_WAIT_INIT
2783
2784		Maximum time to wait for the INIT_B line to de-assert
2785		after PROB_B has been de-asserted during a Virtex II
2786		FPGA configuration sequence. The default time is 500
2787		ms.
2788
2789		CONFIG_SYS_FPGA_WAIT_BUSY
2790
2791		Maximum time to wait for BUSY to de-assert during
2792		Virtex II FPGA configuration. The default is 5 ms.
2793
2794		CONFIG_SYS_FPGA_WAIT_CONFIG
2795
2796		Time to wait after FPGA configuration. The default is
2797		200 ms.
2798
2799- Configuration Management:
2800		CONFIG_BUILD_TARGET
2801
2802		Some SoCs need special image types (e.g. U-Boot binary
2803		with a special header) as build targets. By defining
2804		CONFIG_BUILD_TARGET in the SoC / board header, this
2805		special image will be automatically built upon calling
2806		make / MAKEALL.
2807
2808		CONFIG_IDENT_STRING
2809
2810		If defined, this string will be added to the U-Boot
2811		version information (U_BOOT_VERSION)
2812
2813- Vendor Parameter Protection:
2814
2815		U-Boot considers the values of the environment
2816		variables "serial#" (Board Serial Number) and
2817		"ethaddr" (Ethernet Address) to be parameters that
2818		are set once by the board vendor / manufacturer, and
2819		protects these variables from casual modification by
2820		the user. Once set, these variables are read-only,
2821		and write or delete attempts are rejected. You can
2822		change this behaviour:
2823
2824		If CONFIG_ENV_OVERWRITE is #defined in your config
2825		file, the write protection for vendor parameters is
2826		completely disabled. Anybody can change or delete
2827		these parameters.
2828
2829		Alternatively, if you define _both_ an ethaddr in the
2830		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2831		Ethernet address is installed in the environment,
2832		which can be changed exactly ONCE by the user. [The
2833		serial# is unaffected by this, i. e. it remains
2834		read-only.]
2835
2836		The same can be accomplished in a more flexible way
2837		for any variable by configuring the type of access
2838		to allow for those variables in the ".flags" variable
2839		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2840
2841- Protected RAM:
2842		CONFIG_PRAM
2843
2844		Define this variable to enable the reservation of
2845		"protected RAM", i. e. RAM which is not overwritten
2846		by U-Boot. Define CONFIG_PRAM to hold the number of
2847		kB you want to reserve for pRAM. You can overwrite
2848		this default value by defining an environment
2849		variable "pram" to the number of kB you want to
2850		reserve. Note that the board info structure will
2851		still show the full amount of RAM. If pRAM is
2852		reserved, a new environment variable "mem" will
2853		automatically be defined to hold the amount of
2854		remaining RAM in a form that can be passed as boot
2855		argument to Linux, for instance like that:
2856
2857			setenv bootargs ... mem=\${mem}
2858			saveenv
2859
2860		This way you can tell Linux not to use this memory,
2861		either, which results in a memory region that will
2862		not be affected by reboots.
2863
2864		*WARNING* If your board configuration uses automatic
2865		detection of the RAM size, you must make sure that
2866		this memory test is non-destructive. So far, the
2867		following board configurations are known to be
2868		"pRAM-clean":
2869
2870			IVMS8, IVML24, SPD8xx, TQM8xxL,
2871			HERMES, IP860, RPXlite, LWMON,
2872			FLAGADM, TQM8260
2873
2874- Access to physical memory region (> 4GB)
2875		Some basic support is provided for operations on memory not
2876		normally accessible to U-Boot - e.g. some architectures
2877		support access to more than 4GB of memory on 32-bit
2878		machines using physical address extension or similar.
2879		Define CONFIG_PHYSMEM to access this basic support, which
2880		currently only supports clearing the memory.
2881
2882- Error Recovery:
2883		CONFIG_PANIC_HANG
2884
2885		Define this variable to stop the system in case of a
2886		fatal error, so that you have to reset it manually.
2887		This is probably NOT a good idea for an embedded
2888		system where you want the system to reboot
2889		automatically as fast as possible, but it may be
2890		useful during development since you can try to debug
2891		the conditions that lead to the situation.
2892
2893		CONFIG_NET_RETRY_COUNT
2894
2895		This variable defines the number of retries for
2896		network operations like ARP, RARP, TFTP, or BOOTP
2897		before giving up the operation. If not defined, a
2898		default value of 5 is used.
2899
2900		CONFIG_ARP_TIMEOUT
2901
2902		Timeout waiting for an ARP reply in milliseconds.
2903
2904		CONFIG_NFS_TIMEOUT
2905
2906		Timeout in milliseconds used in NFS protocol.
2907		If you encounter "ERROR: Cannot umount" in nfs command,
2908		try longer timeout such as
2909		#define CONFIG_NFS_TIMEOUT 10000UL
2910
2911- Command Interpreter:
2912		CONFIG_AUTO_COMPLETE
2913
2914		Enable auto completion of commands using TAB.
2915
2916		CONFIG_SYS_PROMPT_HUSH_PS2
2917
2918		This defines the secondary prompt string, which is
2919		printed when the command interpreter needs more input
2920		to complete a command. Usually "> ".
2921
2922	Note:
2923
2924		In the current implementation, the local variables
2925		space and global environment variables space are
2926		separated. Local variables are those you define by
2927		simply typing `name=value'. To access a local
2928		variable later on, you have write `$name' or
2929		`${name}'; to execute the contents of a variable
2930		directly type `$name' at the command prompt.
2931
2932		Global environment variables are those you use
2933		setenv/printenv to work with. To run a command stored
2934		in such a variable, you need to use the run command,
2935		and you must not use the '$' sign to access them.
2936
2937		To store commands and special characters in a
2938		variable, please use double quotation marks
2939		surrounding the whole text of the variable, instead
2940		of the backslashes before semicolons and special
2941		symbols.
2942
2943- Command Line Editing and History:
2944		CONFIG_CMDLINE_EDITING
2945
2946		Enable editing and History functions for interactive
2947		command line input operations
2948
2949- Default Environment:
2950		CONFIG_EXTRA_ENV_SETTINGS
2951
2952		Define this to contain any number of null terminated
2953		strings (variable = value pairs) that will be part of
2954		the default environment compiled into the boot image.
2955
2956		For example, place something like this in your
2957		board's config file:
2958
2959		#define CONFIG_EXTRA_ENV_SETTINGS \
2960			"myvar1=value1\0" \
2961			"myvar2=value2\0"
2962
2963		Warning: This method is based on knowledge about the
2964		internal format how the environment is stored by the
2965		U-Boot code. This is NOT an official, exported
2966		interface! Although it is unlikely that this format
2967		will change soon, there is no guarantee either.
2968		You better know what you are doing here.
2969
2970		Note: overly (ab)use of the default environment is
2971		discouraged. Make sure to check other ways to preset
2972		the environment like the "source" command or the
2973		boot command first.
2974
2975		CONFIG_ENV_VARS_UBOOT_CONFIG
2976
2977		Define this in order to add variables describing the
2978		U-Boot build configuration to the default environment.
2979		These will be named arch, cpu, board, vendor, and soc.
2980
2981		Enabling this option will cause the following to be defined:
2982
2983		- CONFIG_SYS_ARCH
2984		- CONFIG_SYS_CPU
2985		- CONFIG_SYS_BOARD
2986		- CONFIG_SYS_VENDOR
2987		- CONFIG_SYS_SOC
2988
2989		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2990
2991		Define this in order to add variables describing certain
2992		run-time determined information about the hardware to the
2993		environment.  These will be named board_name, board_rev.
2994
2995		CONFIG_DELAY_ENVIRONMENT
2996
2997		Normally the environment is loaded when the board is
2998		initialised so that it is available to U-Boot. This inhibits
2999		that so that the environment is not available until
3000		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
3001		this is instead controlled by the value of
3002		/config/load-environment.
3003
3004- Parallel Flash support:
3005		CONFIG_SYS_NO_FLASH
3006
3007		Traditionally U-boot was run on systems with parallel NOR
3008		flash. This option is used to disable support for parallel NOR
3009		flash. This option should be defined if the board does not have
3010		parallel flash.
3011
3012		If this option is not defined one of the generic flash drivers
3013		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
3014		selected or the board must provide an implementation of the
3015		flash API (see include/flash.h).
3016
3017- DataFlash Support:
3018		CONFIG_HAS_DATAFLASH
3019
3020		Defining this option enables DataFlash features and
3021		allows to read/write in Dataflash via the standard
3022		commands cp, md...
3023
3024- Serial Flash support
3025		CONFIG_CMD_SF
3026
3027		Defining this option enables SPI flash commands
3028		'sf probe/read/write/erase/update'.
3029
3030		Usage requires an initial 'probe' to define the serial
3031		flash parameters, followed by read/write/erase/update
3032		commands.
3033
3034		The following defaults may be provided by the platform
3035		to handle the common case when only a single serial
3036		flash is present on the system.
3037
3038		CONFIG_SF_DEFAULT_BUS		Bus identifier
3039		CONFIG_SF_DEFAULT_CS		Chip-select
3040		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
3041		CONFIG_SF_DEFAULT_SPEED		in Hz
3042
3043		CONFIG_CMD_SF_TEST
3044
3045		Define this option to include a destructive SPI flash
3046		test ('sf test').
3047
3048		CONFIG_SF_DUAL_FLASH		Dual flash memories
3049
3050		Define this option to use dual flash support where two flash
3051		memories can be connected with a given cs line.
3052		Currently Xilinx Zynq qspi supports these type of connections.
3053
3054- SystemACE Support:
3055		CONFIG_SYSTEMACE
3056
3057		Adding this option adds support for Xilinx SystemACE
3058		chips attached via some sort of local bus. The address
3059		of the chip must also be defined in the
3060		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
3061
3062		#define CONFIG_SYSTEMACE
3063		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
3064
3065		When SystemACE support is added, the "ace" device type
3066		becomes available to the fat commands, i.e. fatls.
3067
3068- TFTP Fixed UDP Port:
3069		CONFIG_TFTP_PORT
3070
3071		If this is defined, the environment variable tftpsrcp
3072		is used to supply the TFTP UDP source port value.
3073		If tftpsrcp isn't defined, the normal pseudo-random port
3074		number generator is used.
3075
3076		Also, the environment variable tftpdstp is used to supply
3077		the TFTP UDP destination port value.  If tftpdstp isn't
3078		defined, the normal port 69 is used.
3079
3080		The purpose for tftpsrcp is to allow a TFTP server to
3081		blindly start the TFTP transfer using the pre-configured
3082		target IP address and UDP port. This has the effect of
3083		"punching through" the (Windows XP) firewall, allowing
3084		the remainder of the TFTP transfer to proceed normally.
3085		A better solution is to properly configure the firewall,
3086		but sometimes that is not allowed.
3087
3088- Hashing support:
3089		CONFIG_CMD_HASH
3090
3091		This enables a generic 'hash' command which can produce
3092		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
3093
3094		CONFIG_HASH_VERIFY
3095
3096		Enable the hash verify command (hash -v). This adds to code
3097		size a little.
3098
3099		CONFIG_SHA1 - This option enables support of hashing using SHA1
3100		algorithm. The hash is calculated in software.
3101		CONFIG_SHA256 - This option enables support of hashing using
3102		SHA256 algorithm. The hash is calculated in software.
3103		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
3104		for SHA1/SHA256 hashing.
3105		This affects the 'hash' command and also the
3106		hash_lookup_algo() function.
3107		CONFIG_SHA_PROG_HW_ACCEL - This option enables
3108		hardware-acceleration for SHA1/SHA256 progressive hashing.
3109		Data can be streamed in a block at a time and the hashing
3110		is performed in hardware.
3111
3112		Note: There is also a sha1sum command, which should perhaps
3113		be deprecated in favour of 'hash sha1'.
3114
3115- Freescale i.MX specific commands:
3116		CONFIG_CMD_HDMIDETECT
3117		This enables 'hdmidet' command which returns true if an
3118		HDMI monitor is detected.  This command is i.MX 6 specific.
3119
3120		CONFIG_CMD_BMODE
3121		This enables the 'bmode' (bootmode) command for forcing
3122		a boot from specific media.
3123
3124		This is useful for forcing the ROM's usb downloader to
3125		activate upon a watchdog reset which is nice when iterating
3126		on U-Boot.  Using the reset button or running bmode normal
3127		will set it back to normal.  This command currently
3128		supports i.MX53 and i.MX6.
3129
3130- Signing support:
3131		CONFIG_RSA
3132
3133		This enables the RSA algorithm used for FIT image verification
3134		in U-Boot. See doc/uImage.FIT/signature.txt for more information.
3135
3136		The Modular Exponentiation algorithm in RSA is implemented using
3137		driver model. So CONFIG_DM needs to be enabled by default for this
3138		library to function.
3139
3140		The signing part is build into mkimage regardless of this
3141		option. The software based modular exponentiation is built into
3142		mkimage irrespective of this option.
3143
3144- bootcount support:
3145		CONFIG_BOOTCOUNT_LIMIT
3146
3147		This enables the bootcounter support, see:
3148		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3149
3150		CONFIG_AT91SAM9XE
3151		enable special bootcounter support on at91sam9xe based boards.
3152		CONFIG_BLACKFIN
3153		enable special bootcounter support on blackfin based boards.
3154		CONFIG_SOC_DA8XX
3155		enable special bootcounter support on da850 based boards.
3156		CONFIG_BOOTCOUNT_RAM
3157		enable support for the bootcounter in RAM
3158		CONFIG_BOOTCOUNT_I2C
3159		enable support for the bootcounter on an i2c (like RTC) device.
3160			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3161			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3162						    the bootcounter.
3163			CONFIG_BOOTCOUNT_ALEN = address len
3164
3165- Show boot progress:
3166		CONFIG_SHOW_BOOT_PROGRESS
3167
3168		Defining this option allows to add some board-
3169		specific code (calling a user-provided function
3170		"show_boot_progress(int)") that enables you to show
3171		the system's boot progress on some display (for
3172		example, some LED's) on your board. At the moment,
3173		the following checkpoints are implemented:
3174
3175
3176Legacy uImage format:
3177
3178  Arg	Where			When
3179    1	common/cmd_bootm.c	before attempting to boot an image
3180   -1	common/cmd_bootm.c	Image header has bad	 magic number
3181    2	common/cmd_bootm.c	Image header has correct magic number
3182   -2	common/cmd_bootm.c	Image header has bad	 checksum
3183    3	common/cmd_bootm.c	Image header has correct checksum
3184   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3185    4	common/cmd_bootm.c	Image data   has correct checksum
3186   -4	common/cmd_bootm.c	Image is for unsupported architecture
3187    5	common/cmd_bootm.c	Architecture check OK
3188   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3189    6	common/cmd_bootm.c	Image Type check OK
3190   -6	common/cmd_bootm.c	gunzip uncompression error
3191   -7	common/cmd_bootm.c	Unimplemented compression type
3192    7	common/cmd_bootm.c	Uncompression OK
3193    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3194   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3195
3196    9	common/image.c		Start initial ramdisk verification
3197  -10	common/image.c		Ramdisk header has bad	   magic number
3198  -11	common/image.c		Ramdisk header has bad	   checksum
3199   10	common/image.c		Ramdisk header is OK
3200  -12	common/image.c		Ramdisk data   has bad	   checksum
3201   11	common/image.c		Ramdisk data   has correct checksum
3202   12	common/image.c		Ramdisk verification complete, start loading
3203  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3204   13	common/image.c		Start multifile image verification
3205   14	common/image.c		No initial ramdisk, no multifile, continue.
3206
3207   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3208
3209  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3210  -31	post/post.c		POST test failed, detected by post_output_backlog()
3211  -32	post/post.c		POST test failed, detected by post_run_single()
3212
3213   34	common/cmd_doc.c	before loading a Image from a DOC device
3214  -35	common/cmd_doc.c	Bad usage of "doc" command
3215   35	common/cmd_doc.c	correct usage of "doc" command
3216  -36	common/cmd_doc.c	No boot device
3217   36	common/cmd_doc.c	correct boot device
3218  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3219   37	common/cmd_doc.c	correct chip ID found, device available
3220  -38	common/cmd_doc.c	Read Error on boot device
3221   38	common/cmd_doc.c	reading Image header from DOC device OK
3222  -39	common/cmd_doc.c	Image header has bad magic number
3223   39	common/cmd_doc.c	Image header has correct magic number
3224  -40	common/cmd_doc.c	Error reading Image from DOC device
3225   40	common/cmd_doc.c	Image header has correct magic number
3226   41	common/cmd_ide.c	before loading a Image from a IDE device
3227  -42	common/cmd_ide.c	Bad usage of "ide" command
3228   42	common/cmd_ide.c	correct usage of "ide" command
3229  -43	common/cmd_ide.c	No boot device
3230   43	common/cmd_ide.c	boot device found
3231  -44	common/cmd_ide.c	Device not available
3232   44	common/cmd_ide.c	Device available
3233  -45	common/cmd_ide.c	wrong partition selected
3234   45	common/cmd_ide.c	partition selected
3235  -46	common/cmd_ide.c	Unknown partition table
3236   46	common/cmd_ide.c	valid partition table found
3237  -47	common/cmd_ide.c	Invalid partition type
3238   47	common/cmd_ide.c	correct partition type
3239  -48	common/cmd_ide.c	Error reading Image Header on boot device
3240   48	common/cmd_ide.c	reading Image Header from IDE device OK
3241  -49	common/cmd_ide.c	Image header has bad magic number
3242   49	common/cmd_ide.c	Image header has correct magic number
3243  -50	common/cmd_ide.c	Image header has bad	 checksum
3244   50	common/cmd_ide.c	Image header has correct checksum
3245  -51	common/cmd_ide.c	Error reading Image from IDE device
3246   51	common/cmd_ide.c	reading Image from IDE device OK
3247   52	common/cmd_nand.c	before loading a Image from a NAND device
3248  -53	common/cmd_nand.c	Bad usage of "nand" command
3249   53	common/cmd_nand.c	correct usage of "nand" command
3250  -54	common/cmd_nand.c	No boot device
3251   54	common/cmd_nand.c	boot device found
3252  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3253   55	common/cmd_nand.c	correct chip ID found, device available
3254  -56	common/cmd_nand.c	Error reading Image Header on boot device
3255   56	common/cmd_nand.c	reading Image Header from NAND device OK
3256  -57	common/cmd_nand.c	Image header has bad magic number
3257   57	common/cmd_nand.c	Image header has correct magic number
3258  -58	common/cmd_nand.c	Error reading Image from NAND device
3259   58	common/cmd_nand.c	reading Image from NAND device OK
3260
3261  -60	common/env_common.c	Environment has a bad CRC, using default
3262
3263   64	net/eth.c		starting with Ethernet configuration.
3264  -64	net/eth.c		no Ethernet found.
3265   65	net/eth.c		Ethernet found.
3266
3267  -80	common/cmd_net.c	usage wrong
3268   80	common/cmd_net.c	before calling net_loop()
3269  -81	common/cmd_net.c	some error in net_loop() occurred
3270   81	common/cmd_net.c	net_loop() back without error
3271  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3272   82	common/cmd_net.c	trying automatic boot
3273   83	common/cmd_net.c	running "source" command
3274  -83	common/cmd_net.c	some error in automatic boot or "source" command
3275   84	common/cmd_net.c	end without errors
3276
3277FIT uImage format:
3278
3279  Arg	Where			When
3280  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3281 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3282  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3283 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3284  102	common/cmd_bootm.c	Kernel unit name specified
3285 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3286  103	common/cmd_bootm.c	Found configuration node
3287  104	common/cmd_bootm.c	Got kernel subimage node offset
3288 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3289  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3290 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3291  106	common/cmd_bootm.c	Architecture check OK
3292 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3293  107	common/cmd_bootm.c	Kernel subimage type OK
3294 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3295  108	common/cmd_bootm.c	Got kernel subimage data/size
3296 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3297 -109	common/cmd_bootm.c	Can't get kernel subimage type
3298 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3299 -111	common/cmd_bootm.c	Can't get kernel subimage os
3300 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3301 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3302
3303  120	common/image.c		Start initial ramdisk verification
3304 -120	common/image.c		Ramdisk FIT image has incorrect format
3305  121	common/image.c		Ramdisk FIT image has correct format
3306  122	common/image.c		No ramdisk subimage unit name, using configuration
3307 -122	common/image.c		Can't get configuration for ramdisk subimage
3308  123	common/image.c		Ramdisk unit name specified
3309 -124	common/image.c		Can't get ramdisk subimage node offset
3310  125	common/image.c		Got ramdisk subimage node offset
3311 -125	common/image.c		Ramdisk subimage hash verification failed
3312  126	common/image.c		Ramdisk subimage hash verification OK
3313 -126	common/image.c		Ramdisk subimage for unsupported architecture
3314  127	common/image.c		Architecture check OK
3315 -127	common/image.c		Can't get ramdisk subimage data/size
3316  128	common/image.c		Got ramdisk subimage data/size
3317  129	common/image.c		Can't get ramdisk load address
3318 -129	common/image.c		Got ramdisk load address
3319
3320 -130	common/cmd_doc.c	Incorrect FIT image format
3321  131	common/cmd_doc.c	FIT image format OK
3322
3323 -140	common/cmd_ide.c	Incorrect FIT image format
3324  141	common/cmd_ide.c	FIT image format OK
3325
3326 -150	common/cmd_nand.c	Incorrect FIT image format
3327  151	common/cmd_nand.c	FIT image format OK
3328
3329- legacy image format:
3330		CONFIG_IMAGE_FORMAT_LEGACY
3331		enables the legacy image format support in U-Boot.
3332
3333		Default:
3334		enabled if CONFIG_FIT_SIGNATURE is not defined.
3335
3336		CONFIG_DISABLE_IMAGE_LEGACY
3337		disable the legacy image format
3338
3339		This define is introduced, as the legacy image format is
3340		enabled per default for backward compatibility.
3341
3342- FIT image support:
3343		CONFIG_FIT
3344		Enable support for the FIT uImage format.
3345
3346		CONFIG_FIT_BEST_MATCH
3347		When no configuration is explicitly selected, default to the
3348		one whose fdt's compatibility field best matches that of
3349		U-Boot itself. A match is considered "best" if it matches the
3350		most specific compatibility entry of U-Boot's fdt's root node.
3351		The order of entries in the configuration's fdt is ignored.
3352
3353		CONFIG_FIT_SIGNATURE
3354		This option enables signature verification of FIT uImages,
3355		using a hash signed and verified using RSA. If
3356		CONFIG_SHA_PROG_HW_ACCEL is defined, i.e support for progressive
3357		hashing is available using hardware, RSA library will use it.
3358		See doc/uImage.FIT/signature.txt for more details.
3359
3360		WARNING: When relying on signed FIT images with required
3361		signature check the legacy image format is default
3362		disabled. If a board need legacy image format support
3363		enable this through CONFIG_IMAGE_FORMAT_LEGACY
3364
3365		CONFIG_FIT_DISABLE_SHA256
3366		Supporting SHA256 hashes has quite an impact on binary size.
3367		For constrained systems sha256 hash support can be disabled
3368		with this option.
3369
3370- Standalone program support:
3371		CONFIG_STANDALONE_LOAD_ADDR
3372
3373		This option defines a board specific value for the
3374		address where standalone program gets loaded, thus
3375		overwriting the architecture dependent default
3376		settings.
3377
3378- Frame Buffer Address:
3379		CONFIG_FB_ADDR
3380
3381		Define CONFIG_FB_ADDR if you want to use specific
3382		address for frame buffer.  This is typically the case
3383		when using a graphics controller has separate video
3384		memory.  U-Boot will then place the frame buffer at
3385		the given address instead of dynamically reserving it
3386		in system RAM by calling lcd_setmem(), which grabs
3387		the memory for the frame buffer depending on the
3388		configured panel size.
3389
3390		Please see board_init_f function.
3391
3392- Automatic software updates via TFTP server
3393		CONFIG_UPDATE_TFTP
3394		CONFIG_UPDATE_TFTP_CNT_MAX
3395		CONFIG_UPDATE_TFTP_MSEC_MAX
3396
3397		These options enable and control the auto-update feature;
3398		for a more detailed description refer to doc/README.update.
3399
3400- MTD Support (mtdparts command, UBI support)
3401		CONFIG_MTD_DEVICE
3402
3403		Adds the MTD device infrastructure from the Linux kernel.
3404		Needed for mtdparts command support.
3405
3406		CONFIG_MTD_PARTITIONS
3407
3408		Adds the MTD partitioning infrastructure from the Linux
3409		kernel. Needed for UBI support.
3410
3411- UBI support
3412		CONFIG_CMD_UBI
3413
3414		Adds commands for interacting with MTD partitions formatted
3415		with the UBI flash translation layer
3416
3417		Requires also defining CONFIG_RBTREE
3418
3419		CONFIG_UBI_SILENCE_MSG
3420
3421		Make the verbose messages from UBI stop printing.  This leaves
3422		warnings and errors enabled.
3423
3424
3425		CONFIG_MTD_UBI_WL_THRESHOLD
3426		This parameter defines the maximum difference between the highest
3427		erase counter value and the lowest erase counter value of eraseblocks
3428		of UBI devices. When this threshold is exceeded, UBI starts performing
3429		wear leveling by means of moving data from eraseblock with low erase
3430		counter to eraseblocks with high erase counter.
3431
3432		The default value should be OK for SLC NAND flashes, NOR flashes and
3433		other flashes which have eraseblock life-cycle 100000 or more.
3434		However, in case of MLC NAND flashes which typically have eraseblock
3435		life-cycle less than 10000, the threshold should be lessened (e.g.,
3436		to 128 or 256, although it does not have to be power of 2).
3437
3438		default: 4096
3439
3440		CONFIG_MTD_UBI_BEB_LIMIT
3441		This option specifies the maximum bad physical eraseblocks UBI
3442		expects on the MTD device (per 1024 eraseblocks). If the
3443		underlying flash does not admit of bad eraseblocks (e.g. NOR
3444		flash), this value is ignored.
3445
3446		NAND datasheets often specify the minimum and maximum NVM
3447		(Number of Valid Blocks) for the flashes' endurance lifetime.
3448		The maximum expected bad eraseblocks per 1024 eraseblocks
3449		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3450		which gives 20 for most NANDs (MaxNVB is basically the total
3451		count of eraseblocks on the chip).
3452
3453		To put it differently, if this value is 20, UBI will try to
3454		reserve about 1.9% of physical eraseblocks for bad blocks
3455		handling. And that will be 1.9% of eraseblocks on the entire
3456		NAND chip, not just the MTD partition UBI attaches. This means
3457		that if you have, say, a NAND flash chip admits maximum 40 bad
3458		eraseblocks, and it is split on two MTD partitions of the same
3459		size, UBI will reserve 40 eraseblocks when attaching a
3460		partition.
3461
3462		default: 20
3463
3464		CONFIG_MTD_UBI_FASTMAP
3465		Fastmap is a mechanism which allows attaching an UBI device
3466		in nearly constant time. Instead of scanning the whole MTD device it
3467		only has to locate a checkpoint (called fastmap) on the device.
3468		The on-flash fastmap contains all information needed to attach
3469		the device. Using fastmap makes only sense on large devices where
3470		attaching by scanning takes long. UBI will not automatically install
3471		a fastmap on old images, but you can set the UBI parameter
3472		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3473		that fastmap-enabled images are still usable with UBI implementations
3474		without	fastmap support. On typical flash devices the whole fastmap
3475		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3476
3477		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3478		Set this parameter to enable fastmap automatically on images
3479		without a fastmap.
3480		default: 0
3481
3482		CONFIG_MTD_UBI_FM_DEBUG
3483		Enable UBI fastmap debug
3484		default: 0
3485
3486- UBIFS support
3487		CONFIG_CMD_UBIFS
3488
3489		Adds commands for interacting with UBI volumes formatted as
3490		UBIFS.  UBIFS is read-only in u-boot.
3491
3492		Requires UBI support as well as CONFIG_LZO
3493
3494		CONFIG_UBIFS_SILENCE_MSG
3495
3496		Make the verbose messages from UBIFS stop printing.  This leaves
3497		warnings and errors enabled.
3498
3499- SPL framework
3500		CONFIG_SPL
3501		Enable building of SPL globally.
3502
3503		CONFIG_SPL_LDSCRIPT
3504		LDSCRIPT for linking the SPL binary.
3505
3506		CONFIG_SPL_MAX_FOOTPRINT
3507		Maximum size in memory allocated to the SPL, BSS included.
3508		When defined, the linker checks that the actual memory
3509		used by SPL from _start to __bss_end does not exceed it.
3510		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3511		must not be both defined at the same time.
3512
3513		CONFIG_SPL_MAX_SIZE
3514		Maximum size of the SPL image (text, data, rodata, and
3515		linker lists sections), BSS excluded.
3516		When defined, the linker checks that the actual size does
3517		not exceed it.
3518
3519		CONFIG_SPL_TEXT_BASE
3520		TEXT_BASE for linking the SPL binary.
3521
3522		CONFIG_SPL_RELOC_TEXT_BASE
3523		Address to relocate to.  If unspecified, this is equal to
3524		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3525
3526		CONFIG_SPL_BSS_START_ADDR
3527		Link address for the BSS within the SPL binary.
3528
3529		CONFIG_SPL_BSS_MAX_SIZE
3530		Maximum size in memory allocated to the SPL BSS.
3531		When defined, the linker checks that the actual memory used
3532		by SPL from __bss_start to __bss_end does not exceed it.
3533		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3534		must not be both defined at the same time.
3535
3536		CONFIG_SPL_STACK
3537		Adress of the start of the stack SPL will use
3538
3539		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3540		When defined, SPL will panic() if the image it has
3541		loaded does not have a signature.
3542		Defining this is useful when code which loads images
3543		in SPL cannot guarantee that absolutely all read errors
3544		will be caught.
3545		An example is the LPC32XX MLC NAND driver, which will
3546		consider that a completely unreadable NAND block is bad,
3547		and thus should be skipped silently.
3548
3549		CONFIG_SPL_RELOC_STACK
3550		Adress of the start of the stack SPL will use after
3551		relocation.  If unspecified, this is equal to
3552		CONFIG_SPL_STACK.
3553
3554		CONFIG_SYS_SPL_MALLOC_START
3555		Starting address of the malloc pool used in SPL.
3556		When this option is set the full malloc is used in SPL and
3557		it is set up by spl_init() and before that, the simple malloc()
3558		can be used if CONFIG_SYS_MALLOC_F is defined.
3559
3560		CONFIG_SYS_SPL_MALLOC_SIZE
3561		The size of the malloc pool used in SPL.
3562
3563		CONFIG_SPL_FRAMEWORK
3564		Enable the SPL framework under common/.  This framework
3565		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3566		NAND loading of the Linux Kernel.
3567
3568		CONFIG_SPL_OS_BOOT
3569		Enable booting directly to an OS from SPL.
3570		See also: doc/README.falcon
3571
3572		CONFIG_SPL_DISPLAY_PRINT
3573		For ARM, enable an optional function to print more information
3574		about the running system.
3575
3576		CONFIG_SPL_INIT_MINIMAL
3577		Arch init code should be built for a very small image
3578
3579		CONFIG_SPL_LIBCOMMON_SUPPORT
3580		Support for common/libcommon.o in SPL binary
3581
3582		CONFIG_SPL_LIBDISK_SUPPORT
3583		Support for disk/libdisk.o in SPL binary
3584
3585		CONFIG_SPL_I2C_SUPPORT
3586		Support for drivers/i2c/libi2c.o in SPL binary
3587
3588		CONFIG_SPL_GPIO_SUPPORT
3589		Support for drivers/gpio/libgpio.o in SPL binary
3590
3591		CONFIG_SPL_MMC_SUPPORT
3592		Support for drivers/mmc/libmmc.o in SPL binary
3593
3594		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3595		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3596		Address and partition on the MMC to load U-Boot from
3597		when the MMC is being used in raw mode.
3598
3599		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3600		Partition on the MMC to load U-Boot from when the MMC is being
3601		used in raw mode
3602
3603		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3604		Sector to load kernel uImage from when MMC is being
3605		used in raw mode (for Falcon mode)
3606
3607		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3608		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3609		Sector and number of sectors to load kernel argument
3610		parameters from when MMC is being used in raw mode
3611		(for falcon mode)
3612
3613		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3614		Partition on the MMC to load U-Boot from when the MMC is being
3615		used in fs mode
3616
3617		CONFIG_SPL_FAT_SUPPORT
3618		Support for fs/fat/libfat.o in SPL binary
3619
3620		CONFIG_SPL_EXT_SUPPORT
3621		Support for EXT filesystem in SPL binary
3622
3623		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3624		Filename to read to load U-Boot when reading from filesystem
3625
3626		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3627		Filename to read to load kernel uImage when reading
3628		from filesystem (for Falcon mode)
3629
3630		CONFIG_SPL_FS_LOAD_ARGS_NAME
3631		Filename to read to load kernel argument parameters
3632		when reading from filesystem (for Falcon mode)
3633
3634		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3635		Set this for NAND SPL on PPC mpc83xx targets, so that
3636		start.S waits for the rest of the SPL to load before
3637		continuing (the hardware starts execution after just
3638		loading the first page rather than the full 4K).
3639
3640		CONFIG_SPL_SKIP_RELOCATE
3641		Avoid SPL relocation
3642
3643		CONFIG_SPL_NAND_BASE
3644		Include nand_base.c in the SPL.  Requires
3645		CONFIG_SPL_NAND_DRIVERS.
3646
3647		CONFIG_SPL_NAND_DRIVERS
3648		SPL uses normal NAND drivers, not minimal drivers.
3649
3650		CONFIG_SPL_NAND_ECC
3651		Include standard software ECC in the SPL
3652
3653		CONFIG_SPL_NAND_SIMPLE
3654		Support for NAND boot using simple NAND drivers that
3655		expose the cmd_ctrl() interface.
3656
3657		CONFIG_SPL_MTD_SUPPORT
3658		Support for the MTD subsystem within SPL.  Useful for
3659		environment on NAND support within SPL.
3660
3661		CONFIG_SPL_NAND_RAW_ONLY
3662		Support to boot only raw u-boot.bin images. Use this only
3663		if you need to save space.
3664
3665		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3666		Set for the SPL on PPC mpc8xxx targets, support for
3667		drivers/ddr/fsl/libddr.o in SPL binary.
3668
3669		CONFIG_SPL_COMMON_INIT_DDR
3670		Set for common ddr init with serial presence detect in
3671		SPL binary.
3672
3673		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3674		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3675		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3676		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3677		CONFIG_SYS_NAND_ECCBYTES
3678		Defines the size and behavior of the NAND that SPL uses
3679		to read U-Boot
3680
3681		CONFIG_SPL_NAND_BOOT
3682		Add support NAND boot
3683
3684		CONFIG_SYS_NAND_U_BOOT_OFFS
3685		Location in NAND to read U-Boot from
3686
3687		CONFIG_SYS_NAND_U_BOOT_DST
3688		Location in memory to load U-Boot to
3689
3690		CONFIG_SYS_NAND_U_BOOT_SIZE
3691		Size of image to load
3692
3693		CONFIG_SYS_NAND_U_BOOT_START
3694		Entry point in loaded image to jump to
3695
3696		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3697		Define this if you need to first read the OOB and then the
3698		data. This is used, for example, on davinci platforms.
3699
3700		CONFIG_SPL_OMAP3_ID_NAND
3701		Support for an OMAP3-specific set of functions to return the
3702		ID and MFR of the first attached NAND chip, if present.
3703
3704		CONFIG_SPL_SERIAL_SUPPORT
3705		Support for drivers/serial/libserial.o in SPL binary
3706
3707		CONFIG_SPL_SPI_FLASH_SUPPORT
3708		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3709
3710		CONFIG_SPL_SPI_SUPPORT
3711		Support for drivers/spi/libspi.o in SPL binary
3712
3713		CONFIG_SPL_RAM_DEVICE
3714		Support for running image already present in ram, in SPL binary
3715
3716		CONFIG_SPL_LIBGENERIC_SUPPORT
3717		Support for lib/libgeneric.o in SPL binary
3718
3719		CONFIG_SPL_ENV_SUPPORT
3720		Support for the environment operating in SPL binary
3721
3722		CONFIG_SPL_NET_SUPPORT
3723		Support for the net/libnet.o in SPL binary.
3724		It conflicts with SPL env from storage medium specified by
3725		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3726
3727		CONFIG_SPL_PAD_TO
3728		Image offset to which the SPL should be padded before appending
3729		the SPL payload. By default, this is defined as
3730		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3731		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3732		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3733
3734		CONFIG_SPL_TARGET
3735		Final target image containing SPL and payload.  Some SPLs
3736		use an arch-specific makefile fragment instead, for
3737		example if more than one image needs to be produced.
3738
3739		CONFIG_FIT_SPL_PRINT
3740		Printing information about a FIT image adds quite a bit of
3741		code to SPL. So this is normally disabled in SPL. Use this
3742		option to re-enable it. This will affect the output of the
3743		bootm command when booting a FIT image.
3744
3745- TPL framework
3746		CONFIG_TPL
3747		Enable building of TPL globally.
3748
3749		CONFIG_TPL_PAD_TO
3750		Image offset to which the TPL should be padded before appending
3751		the TPL payload. By default, this is defined as
3752		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3753		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3754		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3755
3756Modem Support:
3757--------------
3758
3759[so far only for SMDK2400 boards]
3760
3761- Modem support enable:
3762		CONFIG_MODEM_SUPPORT
3763
3764- RTS/CTS Flow control enable:
3765		CONFIG_HWFLOW
3766
3767- Modem debug support:
3768		CONFIG_MODEM_SUPPORT_DEBUG
3769
3770		Enables debugging stuff (char screen[1024], dbg())
3771		for modem support. Useful only with BDI2000.
3772
3773- Interrupt support (PPC):
3774
3775		There are common interrupt_init() and timer_interrupt()
3776		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3777		for CPU specific initialization. interrupt_init_cpu()
3778		should set decrementer_count to appropriate value. If
3779		CPU resets decrementer automatically after interrupt
3780		(ppc4xx) it should set decrementer_count to zero.
3781		timer_interrupt() calls timer_interrupt_cpu() for CPU
3782		specific handling. If board has watchdog / status_led
3783		/ other_activity_monitor it works automatically from
3784		general timer_interrupt().
3785
3786- General:
3787
3788		In the target system modem support is enabled when a
3789		specific key (key combination) is pressed during
3790		power-on. Otherwise U-Boot will boot normally
3791		(autoboot). The key_pressed() function is called from
3792		board_init(). Currently key_pressed() is a dummy
3793		function, returning 1 and thus enabling modem
3794		initialization.
3795
3796		If there are no modem init strings in the
3797		environment, U-Boot proceed to autoboot; the
3798		previous output (banner, info printfs) will be
3799		suppressed, though.
3800
3801		See also: doc/README.Modem
3802
3803Board initialization settings:
3804------------------------------
3805
3806During Initialization u-boot calls a number of board specific functions
3807to allow the preparation of board specific prerequisites, e.g. pin setup
3808before drivers are initialized. To enable these callbacks the
3809following configuration macros have to be defined. Currently this is
3810architecture specific, so please check arch/your_architecture/lib/board.c
3811typically in board_init_f() and board_init_r().
3812
3813- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3814- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3815- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3816- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3817
3818Configuration Settings:
3819-----------------------
3820
3821- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3822		Optionally it can be defined to support 64-bit memory commands.
3823
3824- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3825		undefine this when you're short of memory.
3826
3827- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3828		width of the commands listed in the 'help' command output.
3829
3830- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3831		prompt for user input.
3832
3833- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3834
3835- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3836
3837- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3838
3839- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3840		the application (usually a Linux kernel) when it is
3841		booted
3842
3843- CONFIG_SYS_BAUDRATE_TABLE:
3844		List of legal baudrate settings for this board.
3845
3846- CONFIG_SYS_CONSOLE_INFO_QUIET
3847		Suppress display of console information at boot.
3848
3849- CONFIG_SYS_CONSOLE_IS_IN_ENV
3850		If the board specific function
3851			extern int overwrite_console (void);
3852		returns 1, the stdin, stderr and stdout are switched to the
3853		serial port, else the settings in the environment are used.
3854
3855- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3856		Enable the call to overwrite_console().
3857
3858- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3859		Enable overwrite of previous console environment settings.
3860
3861- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3862		Begin and End addresses of the area used by the
3863		simple memory test.
3864
3865- CONFIG_SYS_ALT_MEMTEST:
3866		Enable an alternate, more extensive memory test.
3867
3868- CONFIG_SYS_MEMTEST_SCRATCH:
3869		Scratch address used by the alternate memory test
3870		You only need to set this if address zero isn't writeable
3871
3872- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3873		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3874		this specified memory area will get subtracted from the top
3875		(end) of RAM and won't get "touched" at all by U-Boot. By
3876		fixing up gd->ram_size the Linux kernel should gets passed
3877		the now "corrected" memory size and won't touch it either.
3878		This should work for arch/ppc and arch/powerpc. Only Linux
3879		board ports in arch/powerpc with bootwrapper support that
3880		recalculate the memory size from the SDRAM controller setup
3881		will have to get fixed in Linux additionally.
3882
3883		This option can be used as a workaround for the 440EPx/GRx
3884		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3885		be touched.
3886
3887		WARNING: Please make sure that this value is a multiple of
3888		the Linux page size (normally 4k). If this is not the case,
3889		then the end address of the Linux memory will be located at a
3890		non page size aligned address and this could cause major
3891		problems.
3892
3893- CONFIG_SYS_LOADS_BAUD_CHANGE:
3894		Enable temporary baudrate change while serial download
3895
3896- CONFIG_SYS_SDRAM_BASE:
3897		Physical start address of SDRAM. _Must_ be 0 here.
3898
3899- CONFIG_SYS_MBIO_BASE:
3900		Physical start address of Motherboard I/O (if using a
3901		Cogent motherboard)
3902
3903- CONFIG_SYS_FLASH_BASE:
3904		Physical start address of Flash memory.
3905
3906- CONFIG_SYS_MONITOR_BASE:
3907		Physical start address of boot monitor code (set by
3908		make config files to be same as the text base address
3909		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3910		CONFIG_SYS_FLASH_BASE when booting from flash.
3911
3912- CONFIG_SYS_MONITOR_LEN:
3913		Size of memory reserved for monitor code, used to
3914		determine _at_compile_time_ (!) if the environment is
3915		embedded within the U-Boot image, or in a separate
3916		flash sector.
3917
3918- CONFIG_SYS_MALLOC_LEN:
3919		Size of DRAM reserved for malloc() use.
3920
3921- CONFIG_SYS_MALLOC_F_LEN
3922		Size of the malloc() pool for use before relocation. If
3923		this is defined, then a very simple malloc() implementation
3924		will become available before relocation. The address is just
3925		below the global data, and the stack is moved down to make
3926		space.
3927
3928		This feature allocates regions with increasing addresses
3929		within the region. calloc() is supported, but realloc()
3930		is not available. free() is supported but does nothing.
3931		The memory will be freed (or in fact just forgotten) when
3932		U-Boot relocates itself.
3933
3934		Pre-relocation malloc() is only supported on ARM and sandbox
3935		at present but is fairly easy to enable for other archs.
3936
3937- CONFIG_SYS_MALLOC_SIMPLE
3938		Provides a simple and small malloc() and calloc() for those
3939		boards which do not use the full malloc in SPL (which is
3940		enabled with CONFIG_SYS_SPL_MALLOC_START).
3941
3942- CONFIG_SYS_NONCACHED_MEMORY:
3943		Size of non-cached memory area. This area of memory will be
3944		typically located right below the malloc() area and mapped
3945		uncached in the MMU. This is useful for drivers that would
3946		otherwise require a lot of explicit cache maintenance. For
3947		some drivers it's also impossible to properly maintain the
3948		cache. For example if the regions that need to be flushed
3949		are not a multiple of the cache-line size, *and* padding
3950		cannot be allocated between the regions to align them (i.e.
3951		if the HW requires a contiguous array of regions, and the
3952		size of each region is not cache-aligned), then a flush of
3953		one region may result in overwriting data that hardware has
3954		written to another region in the same cache-line. This can
3955		happen for example in network drivers where descriptors for
3956		buffers are typically smaller than the CPU cache-line (e.g.
3957		16 bytes vs. 32 or 64 bytes).
3958
3959		Non-cached memory is only supported on 32-bit ARM at present.
3960
3961- CONFIG_SYS_BOOTM_LEN:
3962		Normally compressed uImages are limited to an
3963		uncompressed size of 8 MBytes. If this is not enough,
3964		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3965		to adjust this setting to your needs.
3966
3967- CONFIG_SYS_BOOTMAPSZ:
3968		Maximum size of memory mapped by the startup code of
3969		the Linux kernel; all data that must be processed by
3970		the Linux kernel (bd_info, boot arguments, FDT blob if
3971		used) must be put below this limit, unless "bootm_low"
3972		environment variable is defined and non-zero. In such case
3973		all data for the Linux kernel must be between "bootm_low"
3974		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3975		variable "bootm_mapsize" will override the value of
3976		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3977		then the value in "bootm_size" will be used instead.
3978
3979- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3980		Enable initrd_high functionality.  If defined then the
3981		initrd_high feature is enabled and the bootm ramdisk subcommand
3982		is enabled.
3983
3984- CONFIG_SYS_BOOT_GET_CMDLINE:
3985		Enables allocating and saving kernel cmdline in space between
3986		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3987
3988- CONFIG_SYS_BOOT_GET_KBD:
3989		Enables allocating and saving a kernel copy of the bd_info in
3990		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3991
3992- CONFIG_SYS_MAX_FLASH_BANKS:
3993		Max number of Flash memory banks
3994
3995- CONFIG_SYS_MAX_FLASH_SECT:
3996		Max number of sectors on a Flash chip
3997
3998- CONFIG_SYS_FLASH_ERASE_TOUT:
3999		Timeout for Flash erase operations (in ms)
4000
4001- CONFIG_SYS_FLASH_WRITE_TOUT:
4002		Timeout for Flash write operations (in ms)
4003
4004- CONFIG_SYS_FLASH_LOCK_TOUT
4005		Timeout for Flash set sector lock bit operation (in ms)
4006
4007- CONFIG_SYS_FLASH_UNLOCK_TOUT
4008		Timeout for Flash clear lock bits operation (in ms)
4009
4010- CONFIG_SYS_FLASH_PROTECTION
4011		If defined, hardware flash sectors protection is used
4012		instead of U-Boot software protection.
4013
4014- CONFIG_SYS_DIRECT_FLASH_TFTP:
4015
4016		Enable TFTP transfers directly to flash memory;
4017		without this option such a download has to be
4018		performed in two steps: (1) download to RAM, and (2)
4019		copy from RAM to flash.
4020
4021		The two-step approach is usually more reliable, since
4022		you can check if the download worked before you erase
4023		the flash, but in some situations (when system RAM is
4024		too limited to allow for a temporary copy of the
4025		downloaded image) this option may be very useful.
4026
4027- CONFIG_SYS_FLASH_CFI:
4028		Define if the flash driver uses extra elements in the
4029		common flash structure for storing flash geometry.
4030
4031- CONFIG_FLASH_CFI_DRIVER
4032		This option also enables the building of the cfi_flash driver
4033		in the drivers directory
4034
4035- CONFIG_FLASH_CFI_MTD
4036		This option enables the building of the cfi_mtd driver
4037		in the drivers directory. The driver exports CFI flash
4038		to the MTD layer.
4039
4040- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
4041		Use buffered writes to flash.
4042
4043- CONFIG_FLASH_SPANSION_S29WS_N
4044		s29ws-n MirrorBit flash has non-standard addresses for buffered
4045		write commands.
4046
4047- CONFIG_SYS_FLASH_QUIET_TEST
4048		If this option is defined, the common CFI flash doesn't
4049		print it's warning upon not recognized FLASH banks. This
4050		is useful, if some of the configured banks are only
4051		optionally available.
4052
4053- CONFIG_FLASH_SHOW_PROGRESS
4054		If defined (must be an integer), print out countdown
4055		digits and dots.  Recommended value: 45 (9..1) for 80
4056		column displays, 15 (3..1) for 40 column displays.
4057
4058- CONFIG_FLASH_VERIFY
4059		If defined, the content of the flash (destination) is compared
4060		against the source after the write operation. An error message
4061		will be printed when the contents are not identical.
4062		Please note that this option is useless in nearly all cases,
4063		since such flash programming errors usually are detected earlier
4064		while unprotecting/erasing/programming. Please only enable
4065		this option if you really know what you are doing.
4066
4067- CONFIG_SYS_RX_ETH_BUFFER:
4068		Defines the number of Ethernet receive buffers. On some
4069		Ethernet controllers it is recommended to set this value
4070		to 8 or even higher (EEPRO100 or 405 EMAC), since all
4071		buffers can be full shortly after enabling the interface
4072		on high Ethernet traffic.
4073		Defaults to 4 if not defined.
4074
4075- CONFIG_ENV_MAX_ENTRIES
4076
4077	Maximum number of entries in the hash table that is used
4078	internally to store the environment settings. The default
4079	setting is supposed to be generous and should work in most
4080	cases. This setting can be used to tune behaviour; see
4081	lib/hashtable.c for details.
4082
4083- CONFIG_ENV_FLAGS_LIST_DEFAULT
4084- CONFIG_ENV_FLAGS_LIST_STATIC
4085	Enable validation of the values given to environment variables when
4086	calling env set.  Variables can be restricted to only decimal,
4087	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
4088	the variables can also be restricted to IP address or MAC address.
4089
4090	The format of the list is:
4091		type_attribute = [s|d|x|b|i|m]
4092		access_attribute = [a|r|o|c]
4093		attributes = type_attribute[access_attribute]
4094		entry = variable_name[:attributes]
4095		list = entry[,list]
4096
4097	The type attributes are:
4098		s - String (default)
4099		d - Decimal
4100		x - Hexadecimal
4101		b - Boolean ([1yYtT|0nNfF])
4102		i - IP address
4103		m - MAC address
4104
4105	The access attributes are:
4106		a - Any (default)
4107		r - Read-only
4108		o - Write-once
4109		c - Change-default
4110
4111	- CONFIG_ENV_FLAGS_LIST_DEFAULT
4112		Define this to a list (string) to define the ".flags"
4113		environment variable in the default or embedded environment.
4114
4115	- CONFIG_ENV_FLAGS_LIST_STATIC
4116		Define this to a list (string) to define validation that
4117		should be done if an entry is not found in the ".flags"
4118		environment variable.  To override a setting in the static
4119		list, simply add an entry for the same variable name to the
4120		".flags" variable.
4121
4122	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
4123	regular expression. This allows multiple variables to define the same
4124	flags without explicitly listing them for each variable.
4125
4126- CONFIG_ENV_ACCESS_IGNORE_FORCE
4127	If defined, don't allow the -f switch to env set override variable
4128	access flags.
4129
4130- CONFIG_SYS_GENERIC_BOARD
4131	This selects the architecture-generic board system instead of the
4132	architecture-specific board files. It is intended to move boards
4133	to this new framework over time. Defining this will disable the
4134	arch/foo/lib/board.c file and use common/board_f.c and
4135	common/board_r.c instead. To use this option your architecture
4136	must support it (i.e. must select HAVE_GENERIC_BOARD in arch/Kconfig).
4137	If you find problems enabling this option on your board please report
4138	the problem and send patches!
4139
4140- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
4141	This is set by OMAP boards for the max time that reset should
4142	be asserted. See doc/README.omap-reset-time for details on how
4143	the value can be calculated on a given board.
4144
4145- CONFIG_USE_STDINT
4146	If stdint.h is available with your toolchain you can define this
4147	option to enable it. You can provide option 'USE_STDINT=1' when
4148	building U-Boot to enable this.
4149
4150The following definitions that deal with the placement and management
4151of environment data (variable area); in general, we support the
4152following configurations:
4153
4154- CONFIG_BUILD_ENVCRC:
4155
4156	Builds up envcrc with the target environment so that external utils
4157	may easily extract it and embed it in final U-Boot images.
4158
4159- CONFIG_ENV_IS_IN_FLASH:
4160
4161	Define this if the environment is in flash memory.
4162
4163	a) The environment occupies one whole flash sector, which is
4164	   "embedded" in the text segment with the U-Boot code. This
4165	   happens usually with "bottom boot sector" or "top boot
4166	   sector" type flash chips, which have several smaller
4167	   sectors at the start or the end. For instance, such a
4168	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
4169	   such a case you would place the environment in one of the
4170	   4 kB sectors - with U-Boot code before and after it. With
4171	   "top boot sector" type flash chips, you would put the
4172	   environment in one of the last sectors, leaving a gap
4173	   between U-Boot and the environment.
4174
4175	- CONFIG_ENV_OFFSET:
4176
4177	   Offset of environment data (variable area) to the
4178	   beginning of flash memory; for instance, with bottom boot
4179	   type flash chips the second sector can be used: the offset
4180	   for this sector is given here.
4181
4182	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
4183
4184	- CONFIG_ENV_ADDR:
4185
4186	   This is just another way to specify the start address of
4187	   the flash sector containing the environment (instead of
4188	   CONFIG_ENV_OFFSET).
4189
4190	- CONFIG_ENV_SECT_SIZE:
4191
4192	   Size of the sector containing the environment.
4193
4194
4195	b) Sometimes flash chips have few, equal sized, BIG sectors.
4196	   In such a case you don't want to spend a whole sector for
4197	   the environment.
4198
4199	- CONFIG_ENV_SIZE:
4200
4201	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
4202	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
4203	   of this flash sector for the environment. This saves
4204	   memory for the RAM copy of the environment.
4205
4206	   It may also save flash memory if you decide to use this
4207	   when your environment is "embedded" within U-Boot code,
4208	   since then the remainder of the flash sector could be used
4209	   for U-Boot code. It should be pointed out that this is
4210	   STRONGLY DISCOURAGED from a robustness point of view:
4211	   updating the environment in flash makes it always
4212	   necessary to erase the WHOLE sector. If something goes
4213	   wrong before the contents has been restored from a copy in
4214	   RAM, your target system will be dead.
4215
4216	- CONFIG_ENV_ADDR_REDUND
4217	  CONFIG_ENV_SIZE_REDUND
4218
4219	   These settings describe a second storage area used to hold
4220	   a redundant copy of the environment data, so that there is
4221	   a valid backup copy in case there is a power failure during
4222	   a "saveenv" operation.
4223
4224BE CAREFUL! Any changes to the flash layout, and some changes to the
4225source code will make it necessary to adapt <board>/u-boot.lds*
4226accordingly!
4227
4228
4229- CONFIG_ENV_IS_IN_NVRAM:
4230
4231	Define this if you have some non-volatile memory device
4232	(NVRAM, battery buffered SRAM) which you want to use for the
4233	environment.
4234
4235	- CONFIG_ENV_ADDR:
4236	- CONFIG_ENV_SIZE:
4237
4238	  These two #defines are used to determine the memory area you
4239	  want to use for environment. It is assumed that this memory
4240	  can just be read and written to, without any special
4241	  provision.
4242
4243BE CAREFUL! The first access to the environment happens quite early
4244in U-Boot initialization (when we try to get the setting of for the
4245console baudrate). You *MUST* have mapped your NVRAM area then, or
4246U-Boot will hang.
4247
4248Please note that even with NVRAM we still use a copy of the
4249environment in RAM: we could work on NVRAM directly, but we want to
4250keep settings there always unmodified except somebody uses "saveenv"
4251to save the current settings.
4252
4253
4254- CONFIG_ENV_IS_IN_EEPROM:
4255
4256	Use this if you have an EEPROM or similar serial access
4257	device and a driver for it.
4258
4259	- CONFIG_ENV_OFFSET:
4260	- CONFIG_ENV_SIZE:
4261
4262	  These two #defines specify the offset and size of the
4263	  environment area within the total memory of your EEPROM.
4264
4265	- CONFIG_SYS_I2C_EEPROM_ADDR:
4266	  If defined, specified the chip address of the EEPROM device.
4267	  The default address is zero.
4268
4269	- CONFIG_SYS_I2C_EEPROM_BUS:
4270	  If defined, specified the i2c bus of the EEPROM device.
4271
4272	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4273	  If defined, the number of bits used to address bytes in a
4274	  single page in the EEPROM device.  A 64 byte page, for example
4275	  would require six bits.
4276
4277	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4278	  If defined, the number of milliseconds to delay between
4279	  page writes.	The default is zero milliseconds.
4280
4281	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4282	  The length in bytes of the EEPROM memory array address.  Note
4283	  that this is NOT the chip address length!
4284
4285	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4286	  EEPROM chips that implement "address overflow" are ones
4287	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4288	  address and the extra bits end up in the "chip address" bit
4289	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4290	  byte chips.
4291
4292	  Note that we consider the length of the address field to
4293	  still be one byte because the extra address bits are hidden
4294	  in the chip address.
4295
4296	- CONFIG_SYS_EEPROM_SIZE:
4297	  The size in bytes of the EEPROM device.
4298
4299	- CONFIG_ENV_EEPROM_IS_ON_I2C
4300	  define this, if you have I2C and SPI activated, and your
4301	  EEPROM, which holds the environment, is on the I2C bus.
4302
4303	- CONFIG_I2C_ENV_EEPROM_BUS
4304	  if you have an Environment on an EEPROM reached over
4305	  I2C muxes, you can define here, how to reach this
4306	  EEPROM. For example:
4307
4308	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4309
4310	  EEPROM which holds the environment, is reached over
4311	  a pca9547 i2c mux with address 0x70, channel 3.
4312
4313- CONFIG_ENV_IS_IN_DATAFLASH:
4314
4315	Define this if you have a DataFlash memory device which you
4316	want to use for the environment.
4317
4318	- CONFIG_ENV_OFFSET:
4319	- CONFIG_ENV_ADDR:
4320	- CONFIG_ENV_SIZE:
4321
4322	  These three #defines specify the offset and size of the
4323	  environment area within the total memory of your DataFlash placed
4324	  at the specified address.
4325
4326- CONFIG_ENV_IS_IN_SPI_FLASH:
4327
4328	Define this if you have a SPI Flash memory device which you
4329	want to use for the environment.
4330
4331	- CONFIG_ENV_OFFSET:
4332	- CONFIG_ENV_SIZE:
4333
4334	  These two #defines specify the offset and size of the
4335	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4336	  aligned to an erase sector boundary.
4337
4338	- CONFIG_ENV_SECT_SIZE:
4339
4340	  Define the SPI flash's sector size.
4341
4342	- CONFIG_ENV_OFFSET_REDUND (optional):
4343
4344	  This setting describes a second storage area of CONFIG_ENV_SIZE
4345	  size used to hold a redundant copy of the environment data, so
4346	  that there is a valid backup copy in case there is a power failure
4347	  during a "saveenv" operation. CONFIG_ENV_OFFSET_RENDUND must be
4348	  aligned to an erase sector boundary.
4349
4350	- CONFIG_ENV_SPI_BUS (optional):
4351	- CONFIG_ENV_SPI_CS (optional):
4352
4353	  Define the SPI bus and chip select. If not defined they will be 0.
4354
4355	- CONFIG_ENV_SPI_MAX_HZ (optional):
4356
4357	  Define the SPI max work clock. If not defined then use 1MHz.
4358
4359	- CONFIG_ENV_SPI_MODE (optional):
4360
4361	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4362
4363- CONFIG_ENV_IS_IN_REMOTE:
4364
4365	Define this if you have a remote memory space which you
4366	want to use for the local device's environment.
4367
4368	- CONFIG_ENV_ADDR:
4369	- CONFIG_ENV_SIZE:
4370
4371	  These two #defines specify the address and size of the
4372	  environment area within the remote memory space. The
4373	  local device can get the environment from remote memory
4374	  space by SRIO or PCIE links.
4375
4376BE CAREFUL! For some special cases, the local device can not use
4377"saveenv" command. For example, the local device will get the
4378environment stored in a remote NOR flash by SRIO or PCIE link,
4379but it can not erase, write this NOR flash by SRIO or PCIE interface.
4380
4381- CONFIG_ENV_IS_IN_NAND:
4382
4383	Define this if you have a NAND device which you want to use
4384	for the environment.
4385
4386	- CONFIG_ENV_OFFSET:
4387	- CONFIG_ENV_SIZE:
4388
4389	  These two #defines specify the offset and size of the environment
4390	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4391	  aligned to an erase block boundary.
4392
4393	- CONFIG_ENV_OFFSET_REDUND (optional):
4394
4395	  This setting describes a second storage area of CONFIG_ENV_SIZE
4396	  size used to hold a redundant copy of the environment data, so
4397	  that there is a valid backup copy in case there is a power failure
4398	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
4399	  aligned to an erase block boundary.
4400
4401	- CONFIG_ENV_RANGE (optional):
4402
4403	  Specifies the length of the region in which the environment
4404	  can be written.  This should be a multiple of the NAND device's
4405	  block size.  Specifying a range with more erase blocks than
4406	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4407	  the range to be avoided.
4408
4409	- CONFIG_ENV_OFFSET_OOB (optional):
4410
4411	  Enables support for dynamically retrieving the offset of the
4412	  environment from block zero's out-of-band data.  The
4413	  "nand env.oob" command can be used to record this offset.
4414	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4415	  using CONFIG_ENV_OFFSET_OOB.
4416
4417- CONFIG_NAND_ENV_DST
4418
4419	Defines address in RAM to which the nand_spl code should copy the
4420	environment. If redundant environment is used, it will be copied to
4421	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4422
4423- CONFIG_ENV_IS_IN_UBI:
4424
4425	Define this if you have an UBI volume that you want to use for the
4426	environment.  This has the benefit of wear-leveling the environment
4427	accesses, which is important on NAND.
4428
4429	- CONFIG_ENV_UBI_PART:
4430
4431	  Define this to a string that is the mtd partition containing the UBI.
4432
4433	- CONFIG_ENV_UBI_VOLUME:
4434
4435	  Define this to the name of the volume that you want to store the
4436	  environment in.
4437
4438	- CONFIG_ENV_UBI_VOLUME_REDUND:
4439
4440	  Define this to the name of another volume to store a second copy of
4441	  the environment in.  This will enable redundant environments in UBI.
4442	  It is assumed that both volumes are in the same MTD partition.
4443
4444	- CONFIG_UBI_SILENCE_MSG
4445	- CONFIG_UBIFS_SILENCE_MSG
4446
4447	  You will probably want to define these to avoid a really noisy system
4448	  when storing the env in UBI.
4449
4450- CONFIG_ENV_IS_IN_FAT:
4451       Define this if you want to use the FAT file system for the environment.
4452
4453       - FAT_ENV_INTERFACE:
4454
4455         Define this to a string that is the name of the block device.
4456
4457       - FAT_ENV_DEV_AND_PART:
4458
4459         Define this to a string to specify the partition of the device. It can
4460         be as following:
4461
4462           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4463               - "D:P": device D partition P. Error occurs if device D has no
4464                        partition table.
4465               - "D:0": device D.
4466               - "D" or "D:": device D partition 1 if device D has partition
4467                              table, or the whole device D if has no partition
4468                              table.
4469               - "D:auto": first partition in device D with bootable flag set.
4470                           If none, first valid partition in device D. If no
4471                           partition table then means device D.
4472
4473       - FAT_ENV_FILE:
4474
4475         It's a string of the FAT file name. This file use to store the
4476         environment.
4477
4478       - CONFIG_FAT_WRITE:
4479         This should be defined. Otherwise it cannot save the environment file.
4480
4481- CONFIG_ENV_IS_IN_MMC:
4482
4483	Define this if you have an MMC device which you want to use for the
4484	environment.
4485
4486	- CONFIG_SYS_MMC_ENV_DEV:
4487
4488	  Specifies which MMC device the environment is stored in.
4489
4490	- CONFIG_SYS_MMC_ENV_PART (optional):
4491
4492	  Specifies which MMC partition the environment is stored in. If not
4493	  set, defaults to partition 0, the user area. Common values might be
4494	  1 (first MMC boot partition), 2 (second MMC boot partition).
4495
4496	- CONFIG_ENV_OFFSET:
4497	- CONFIG_ENV_SIZE:
4498
4499	  These two #defines specify the offset and size of the environment
4500	  area within the specified MMC device.
4501
4502	  If offset is positive (the usual case), it is treated as relative to
4503	  the start of the MMC partition. If offset is negative, it is treated
4504	  as relative to the end of the MMC partition. This can be useful if
4505	  your board may be fitted with different MMC devices, which have
4506	  different sizes for the MMC partitions, and you always want the
4507	  environment placed at the very end of the partition, to leave the
4508	  maximum possible space before it, to store other data.
4509
4510	  These two values are in units of bytes, but must be aligned to an
4511	  MMC sector boundary.
4512
4513	- CONFIG_ENV_OFFSET_REDUND (optional):
4514
4515	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4516	  hold a redundant copy of the environment data. This provides a
4517	  valid backup copy in case the other copy is corrupted, e.g. due
4518	  to a power failure during a "saveenv" operation.
4519
4520	  This value may also be positive or negative; this is handled in the
4521	  same way as CONFIG_ENV_OFFSET.
4522
4523	  This value is also in units of bytes, but must also be aligned to
4524	  an MMC sector boundary.
4525
4526	- CONFIG_ENV_SIZE_REDUND (optional):
4527
4528	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4529	  set. If this value is set, it must be set to the same value as
4530	  CONFIG_ENV_SIZE.
4531
4532- CONFIG_SYS_SPI_INIT_OFFSET
4533
4534	Defines offset to the initial SPI buffer area in DPRAM. The
4535	area is used at an early stage (ROM part) if the environment
4536	is configured to reside in the SPI EEPROM: We need a 520 byte
4537	scratch DPRAM area. It is used between the two initialization
4538	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4539	to be a good choice since it makes it far enough from the
4540	start of the data area as well as from the stack pointer.
4541
4542Please note that the environment is read-only until the monitor
4543has been relocated to RAM and a RAM copy of the environment has been
4544created; also, when using EEPROM you will have to use getenv_f()
4545until then to read environment variables.
4546
4547The environment is protected by a CRC32 checksum. Before the monitor
4548is relocated into RAM, as a result of a bad CRC you will be working
4549with the compiled-in default environment - *silently*!!! [This is
4550necessary, because the first environment variable we need is the
4551"baudrate" setting for the console - if we have a bad CRC, we don't
4552have any device yet where we could complain.]
4553
4554Note: once the monitor has been relocated, then it will complain if
4555the default environment is used; a new CRC is computed as soon as you
4556use the "saveenv" command to store a valid environment.
4557
4558- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4559		Echo the inverted Ethernet link state to the fault LED.
4560
4561		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4562		      also needs to be defined.
4563
4564- CONFIG_SYS_FAULT_MII_ADDR:
4565		MII address of the PHY to check for the Ethernet link state.
4566
4567- CONFIG_NS16550_MIN_FUNCTIONS:
4568		Define this if you desire to only have use of the NS16550_init
4569		and NS16550_putc functions for the serial driver located at
4570		drivers/serial/ns16550.c.  This option is useful for saving
4571		space for already greatly restricted images, including but not
4572		limited to NAND_SPL configurations.
4573
4574- CONFIG_DISPLAY_BOARDINFO
4575		Display information about the board that U-Boot is running on
4576		when U-Boot starts up. The board function checkboard() is called
4577		to do this.
4578
4579- CONFIG_DISPLAY_BOARDINFO_LATE
4580		Similar to the previous option, but display this information
4581		later, once stdio is running and output goes to the LCD, if
4582		present.
4583
4584- CONFIG_BOARD_SIZE_LIMIT:
4585		Maximum size of the U-Boot image. When defined, the
4586		build system checks that the actual size does not
4587		exceed it.
4588
4589Low Level (hardware related) configuration options:
4590---------------------------------------------------
4591
4592- CONFIG_SYS_CACHELINE_SIZE:
4593		Cache Line Size of the CPU.
4594
4595- CONFIG_SYS_DEFAULT_IMMR:
4596		Default address of the IMMR after system reset.
4597
4598		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4599		and RPXsuper) to be able to adjust the position of
4600		the IMMR register after a reset.
4601
4602- CONFIG_SYS_CCSRBAR_DEFAULT:
4603		Default (power-on reset) physical address of CCSR on Freescale
4604		PowerPC SOCs.
4605
4606- CONFIG_SYS_CCSRBAR:
4607		Virtual address of CCSR.  On a 32-bit build, this is typically
4608		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4609
4610		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4611		for cross-platform code that uses that macro instead.
4612
4613- CONFIG_SYS_CCSRBAR_PHYS:
4614		Physical address of CCSR.  CCSR can be relocated to a new
4615		physical address, if desired.  In this case, this macro should
4616		be set to that address.	 Otherwise, it should be set to the
4617		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4618		is typically relocated on 36-bit builds.  It is recommended
4619		that this macro be defined via the _HIGH and _LOW macros:
4620
4621		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4622			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4623
4624- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4625		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4626		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4627		used in assembly code, so it must not contain typecasts or
4628		integer size suffixes (e.g. "ULL").
4629
4630- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4631		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4632		used in assembly code, so it must not contain typecasts or
4633		integer size suffixes (e.g. "ULL").
4634
4635- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4636		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4637		forced to a value that ensures that CCSR is not relocated.
4638
4639- Floppy Disk Support:
4640		CONFIG_SYS_FDC_DRIVE_NUMBER
4641
4642		the default drive number (default value 0)
4643
4644		CONFIG_SYS_ISA_IO_STRIDE
4645
4646		defines the spacing between FDC chipset registers
4647		(default value 1)
4648
4649		CONFIG_SYS_ISA_IO_OFFSET
4650
4651		defines the offset of register from address. It
4652		depends on which part of the data bus is connected to
4653		the FDC chipset. (default value 0)
4654
4655		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4656		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4657		default value.
4658
4659		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4660		fdc_hw_init() is called at the beginning of the FDC
4661		setup. fdc_hw_init() must be provided by the board
4662		source code. It is used to make hardware-dependent
4663		initializations.
4664
4665- CONFIG_IDE_AHB:
4666		Most IDE controllers were designed to be connected with PCI
4667		interface. Only few of them were designed for AHB interface.
4668		When software is doing ATA command and data transfer to
4669		IDE devices through IDE-AHB controller, some additional
4670		registers accessing to these kind of IDE-AHB controller
4671		is required.
4672
4673- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4674		DO NOT CHANGE unless you know exactly what you're
4675		doing! (11-4) [MPC8xx/82xx systems only]
4676
4677- CONFIG_SYS_INIT_RAM_ADDR:
4678
4679		Start address of memory area that can be used for
4680		initial data and stack; please note that this must be
4681		writable memory that is working WITHOUT special
4682		initialization, i. e. you CANNOT use normal RAM which
4683		will become available only after programming the
4684		memory controller and running certain initialization
4685		sequences.
4686
4687		U-Boot uses the following memory types:
4688		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4689		- MPC824X: data cache
4690		- PPC4xx:  data cache
4691
4692- CONFIG_SYS_GBL_DATA_OFFSET:
4693
4694		Offset of the initial data structure in the memory
4695		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4696		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4697		data is located at the end of the available space
4698		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4699		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4700		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4701		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4702
4703	Note:
4704		On the MPC824X (or other systems that use the data
4705		cache for initial memory) the address chosen for
4706		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4707		point to an otherwise UNUSED address space between
4708		the top of RAM and the start of the PCI space.
4709
4710- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4711
4712- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4713
4714- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4715
4716- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4717
4718- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4719
4720- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4721
4722- CONFIG_SYS_OR_TIMING_SDRAM:
4723		SDRAM timing
4724
4725- CONFIG_SYS_MAMR_PTA:
4726		periodic timer for refresh
4727
4728- CONFIG_SYS_DER:	Debug Event Register (37-47)
4729
4730- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4731  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4732  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4733  CONFIG_SYS_BR1_PRELIM:
4734		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4735
4736- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4737  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4738  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4739		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4740
4741- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4742  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4743		Machine Mode Register and Memory Periodic Timer
4744		Prescaler definitions (SDRAM timing)
4745
4746- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4747		enable I2C microcode relocation patch (MPC8xx);
4748		define relocation offset in DPRAM [DSP2]
4749
4750- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4751		enable SMC microcode relocation patch (MPC8xx);
4752		define relocation offset in DPRAM [SMC1]
4753
4754- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4755		enable SPI microcode relocation patch (MPC8xx);
4756		define relocation offset in DPRAM [SCC4]
4757
4758- CONFIG_SYS_USE_OSCCLK:
4759		Use OSCM clock mode on MBX8xx board. Be careful,
4760		wrong setting might damage your board. Read
4761		doc/README.MBX before setting this variable!
4762
4763- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4764		Offset of the bootmode word in DPRAM used by post
4765		(Power On Self Tests). This definition overrides
4766		#define'd default value in commproc.h resp.
4767		cpm_8260.h.
4768
4769- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4770  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4771  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4772  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4773  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4774  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4775  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4776  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4777		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4778
4779- CONFIG_PCI_DISABLE_PCIE:
4780		Disable PCI-Express on systems where it is supported but not
4781		required.
4782
4783- CONFIG_PCI_ENUM_ONLY
4784		Only scan through and get the devices on the buses.
4785		Don't do any setup work, presumably because someone or
4786		something has already done it, and we don't need to do it
4787		a second time.	Useful for platforms that are pre-booted
4788		by coreboot or similar.
4789
4790- CONFIG_PCI_INDIRECT_BRIDGE:
4791		Enable support for indirect PCI bridges.
4792
4793- CONFIG_SYS_SRIO:
4794		Chip has SRIO or not
4795
4796- CONFIG_SRIO1:
4797		Board has SRIO 1 port available
4798
4799- CONFIG_SRIO2:
4800		Board has SRIO 2 port available
4801
4802- CONFIG_SRIO_PCIE_BOOT_MASTER
4803		Board can support master function for Boot from SRIO and PCIE
4804
4805- CONFIG_SYS_SRIOn_MEM_VIRT:
4806		Virtual Address of SRIO port 'n' memory region
4807
4808- CONFIG_SYS_SRIOn_MEM_PHYS:
4809		Physical Address of SRIO port 'n' memory region
4810
4811- CONFIG_SYS_SRIOn_MEM_SIZE:
4812		Size of SRIO port 'n' memory region
4813
4814- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4815		Defined to tell the NAND controller that the NAND chip is using
4816		a 16 bit bus.
4817		Not all NAND drivers use this symbol.
4818		Example of drivers that use it:
4819		- drivers/mtd/nand/ndfc.c
4820		- drivers/mtd/nand/mxc_nand.c
4821
4822- CONFIG_SYS_NDFC_EBC0_CFG
4823		Sets the EBC0_CFG register for the NDFC. If not defined
4824		a default value will be used.
4825
4826- CONFIG_SPD_EEPROM
4827		Get DDR timing information from an I2C EEPROM. Common
4828		with pluggable memory modules such as SODIMMs
4829
4830  SPD_EEPROM_ADDRESS
4831		I2C address of the SPD EEPROM
4832
4833- CONFIG_SYS_SPD_BUS_NUM
4834		If SPD EEPROM is on an I2C bus other than the first
4835		one, specify here. Note that the value must resolve
4836		to something your driver can deal with.
4837
4838- CONFIG_SYS_DDR_RAW_TIMING
4839		Get DDR timing information from other than SPD. Common with
4840		soldered DDR chips onboard without SPD. DDR raw timing
4841		parameters are extracted from datasheet and hard-coded into
4842		header files or board specific files.
4843
4844- CONFIG_FSL_DDR_INTERACTIVE
4845		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4846
4847- CONFIG_FSL_DDR_SYNC_REFRESH
4848		Enable sync of refresh for multiple controllers.
4849
4850- CONFIG_FSL_DDR_BIST
4851		Enable built-in memory test for Freescale DDR controllers.
4852
4853- CONFIG_SYS_83XX_DDR_USES_CS0
4854		Only for 83xx systems. If specified, then DDR should
4855		be configured using CS0 and CS1 instead of CS2 and CS3.
4856
4857- CONFIG_ETHER_ON_FEC[12]
4858		Define to enable FEC[12] on a 8xx series processor.
4859
4860- CONFIG_FEC[12]_PHY
4861		Define to the hardcoded PHY address which corresponds
4862		to the given FEC; i. e.
4863			#define CONFIG_FEC1_PHY 4
4864		means that the PHY with address 4 is connected to FEC1
4865
4866		When set to -1, means to probe for first available.
4867
4868- CONFIG_FEC[12]_PHY_NORXERR
4869		The PHY does not have a RXERR line (RMII only).
4870		(so program the FEC to ignore it).
4871
4872- CONFIG_RMII
4873		Enable RMII mode for all FECs.
4874		Note that this is a global option, we can't
4875		have one FEC in standard MII mode and another in RMII mode.
4876
4877- CONFIG_CRC32_VERIFY
4878		Add a verify option to the crc32 command.
4879		The syntax is:
4880
4881		=> crc32 -v <address> <count> <crc32>
4882
4883		Where address/count indicate a memory area
4884		and crc32 is the correct crc32 which the
4885		area should have.
4886
4887- CONFIG_LOOPW
4888		Add the "loopw" memory command. This only takes effect if
4889		the memory commands are activated globally (CONFIG_CMD_MEM).
4890
4891- CONFIG_MX_CYCLIC
4892		Add the "mdc" and "mwc" memory commands. These are cyclic
4893		"md/mw" commands.
4894		Examples:
4895
4896		=> mdc.b 10 4 500
4897		This command will print 4 bytes (10,11,12,13) each 500 ms.
4898
4899		=> mwc.l 100 12345678 10
4900		This command will write 12345678 to address 100 all 10 ms.
4901
4902		This only takes effect if the memory commands are activated
4903		globally (CONFIG_CMD_MEM).
4904
4905- CONFIG_SKIP_LOWLEVEL_INIT
4906		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4907		low level initializations (like setting up the memory
4908		controller) are omitted and/or U-Boot does not
4909		relocate itself into RAM.
4910
4911		Normally this variable MUST NOT be defined. The only
4912		exception is when U-Boot is loaded (to RAM) by some
4913		other boot loader or by a debugger which performs
4914		these initializations itself.
4915
4916- CONFIG_SPL_BUILD
4917		Modifies the behaviour of start.S when compiling a loader
4918		that is executed before the actual U-Boot. E.g. when
4919		compiling a NAND SPL.
4920
4921- CONFIG_TPL_BUILD
4922		Modifies the behaviour of start.S  when compiling a loader
4923		that is executed after the SPL and before the actual U-Boot.
4924		It is loaded by the SPL.
4925
4926- CONFIG_SYS_MPC85XX_NO_RESETVEC
4927		Only for 85xx systems. If this variable is specified, the section
4928		.resetvec is not kept and the section .bootpg is placed in the
4929		previous 4k of the .text section.
4930
4931- CONFIG_ARCH_MAP_SYSMEM
4932		Generally U-Boot (and in particular the md command) uses
4933		effective address. It is therefore not necessary to regard
4934		U-Boot address as virtual addresses that need to be translated
4935		to physical addresses. However, sandbox requires this, since
4936		it maintains its own little RAM buffer which contains all
4937		addressable memory. This option causes some memory accesses
4938		to be mapped through map_sysmem() / unmap_sysmem().
4939
4940- CONFIG_USE_ARCH_MEMCPY
4941  CONFIG_USE_ARCH_MEMSET
4942		If these options are used a optimized version of memcpy/memset will
4943		be used if available. These functions may be faster under some
4944		conditions but may increase the binary size.
4945
4946- CONFIG_X86_RESET_VECTOR
4947		If defined, the x86 reset vector code is included. This is not
4948		needed when U-Boot is running from Coreboot.
4949
4950- CONFIG_SYS_MPUCLK
4951		Defines the MPU clock speed (in MHz).
4952
4953		NOTE : currently only supported on AM335x platforms.
4954
4955- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4956		Enables the RTC32K OSC on AM33xx based plattforms
4957
4958- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4959		Option to disable subpage write in NAND driver
4960		driver that uses this:
4961		drivers/mtd/nand/davinci_nand.c
4962
4963Freescale QE/FMAN Firmware Support:
4964-----------------------------------
4965
4966The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4967loading of "firmware", which is encoded in the QE firmware binary format.
4968This firmware often needs to be loaded during U-Boot booting, so macros
4969are used to identify the storage device (NOR flash, SPI, etc) and the address
4970within that device.
4971
4972- CONFIG_SYS_FMAN_FW_ADDR
4973	The address in the storage device where the FMAN microcode is located.  The
4974	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4975	is also specified.
4976
4977- CONFIG_SYS_QE_FW_ADDR
4978	The address in the storage device where the QE microcode is located.  The
4979	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4980	is also specified.
4981
4982- CONFIG_SYS_QE_FMAN_FW_LENGTH
4983	The maximum possible size of the firmware.  The firmware binary format
4984	has a field that specifies the actual size of the firmware, but it
4985	might not be possible to read any part of the firmware unless some
4986	local storage is allocated to hold the entire firmware first.
4987
4988- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4989	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4990	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4991	virtual address in NOR flash.
4992
4993- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4994	Specifies that QE/FMAN firmware is located in NAND flash.
4995	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4996
4997- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4998	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4999	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5000
5001- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
5002	Specifies that QE/FMAN firmware is located on the primary SPI
5003	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
5004
5005- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
5006	Specifies that QE/FMAN firmware is located in the remote (master)
5007	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
5008	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
5009	window->master inbound window->master LAW->the ucode address in
5010	master's memory space.
5011
5012Freescale Layerscape Management Complex Firmware Support:
5013---------------------------------------------------------
5014The Freescale Layerscape Management Complex (MC) supports the loading of
5015"firmware".
5016This firmware often needs to be loaded during U-Boot booting, so macros
5017are used to identify the storage device (NOR flash, SPI, etc) and the address
5018within that device.
5019
5020- CONFIG_FSL_MC_ENET
5021	Enable the MC driver for Layerscape SoCs.
5022
5023- CONFIG_SYS_LS_MC_FW_ADDR
5024	The address in the storage device where the firmware is located.  The
5025	meaning of this address depends on which CONFIG_SYS_LS_MC_FW_IN_xxx macro
5026	is also specified.
5027
5028- CONFIG_SYS_LS_MC_FW_LENGTH
5029	The maximum possible size of the firmware.  The firmware binary format
5030	has a field that specifies the actual size of the firmware, but it
5031	might not be possible to read any part of the firmware unless some
5032	local storage is allocated to hold the entire firmware first.
5033
5034- CONFIG_SYS_LS_MC_FW_IN_NOR
5035	Specifies that MC firmware is located in NOR flash, mapped as
5036	normal addressable memory via the LBC. CONFIG_SYS_LS_MC_FW_ADDR is the
5037	virtual address in NOR flash.
5038
5039Freescale Layerscape Debug Server Support:
5040-------------------------------------------
5041The Freescale Layerscape Debug Server Support supports the loading of
5042"Debug Server firmware" and triggering SP boot-rom.
5043This firmware often needs to be loaded during U-Boot booting.
5044
5045- CONFIG_FSL_DEBUG_SERVER
5046	Enable the Debug Server for Layerscape SoCs.
5047
5048- CONFIG_SYS_DEBUG_SERVER_DRAM_BLOCK_MIN_SIZE
5049	Define minimum DDR size required for debug server image
5050
5051- CONFIG_SYS_MEM_TOP_HIDE_MIN
5052	Define minimum DDR size to be hided from top of the DDR memory
5053
5054Reproducible builds
5055-------------------
5056
5057In order to achieve reproducible builds, timestamps used in the U-Boot build
5058process have to be set to a fixed value.
5059
5060This is done using the SOURCE_DATE_EPOCH environment variable.
5061SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
5062option for U-Boot or an environment variable in U-Boot.
5063
5064SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
5065
5066Building the Software:
5067======================
5068
5069Building U-Boot has been tested in several native build environments
5070and in many different cross environments. Of course we cannot support
5071all possibly existing versions of cross development tools in all
5072(potentially obsolete) versions. In case of tool chain problems we
5073recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
5074which is extensively used to build and test U-Boot.
5075
5076If you are not using a native environment, it is assumed that you
5077have GNU cross compiling tools available in your path. In this case,
5078you must set the environment variable CROSS_COMPILE in your shell.
5079Note that no changes to the Makefile or any other source files are
5080necessary. For example using the ELDK on a 4xx CPU, please enter:
5081
5082	$ CROSS_COMPILE=ppc_4xx-
5083	$ export CROSS_COMPILE
5084
5085Note: If you wish to generate Windows versions of the utilities in
5086      the tools directory you can use the MinGW toolchain
5087      (http://www.mingw.org).  Set your HOST tools to the MinGW
5088      toolchain and execute 'make tools'.  For example:
5089
5090       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
5091
5092      Binaries such as tools/mkimage.exe will be created which can
5093      be executed on computers running Windows.
5094
5095U-Boot is intended to be simple to build. After installing the
5096sources you must configure U-Boot for one specific board type. This
5097is done by typing:
5098
5099	make NAME_defconfig
5100
5101where "NAME_defconfig" is the name of one of the existing configu-
5102rations; see boards.cfg for supported names.
5103
5104Note: for some board special configuration names may exist; check if
5105      additional information is available from the board vendor; for
5106      instance, the TQM823L systems are available without (standard)
5107      or with LCD support. You can select such additional "features"
5108      when choosing the configuration, i. e.
5109
5110      make TQM823L_defconfig
5111	- will configure for a plain TQM823L, i. e. no LCD support
5112
5113      make TQM823L_LCD_defconfig
5114	- will configure for a TQM823L with U-Boot console on LCD
5115
5116      etc.
5117
5118
5119Finally, type "make all", and you should get some working U-Boot
5120images ready for download to / installation on your system:
5121
5122- "u-boot.bin" is a raw binary image
5123- "u-boot" is an image in ELF binary format
5124- "u-boot.srec" is in Motorola S-Record format
5125
5126By default the build is performed locally and the objects are saved
5127in the source directory. One of the two methods can be used to change
5128this behavior and build U-Boot to some external directory:
5129
51301. Add O= to the make command line invocations:
5131
5132	make O=/tmp/build distclean
5133	make O=/tmp/build NAME_defconfig
5134	make O=/tmp/build all
5135
51362. Set environment variable KBUILD_OUTPUT to point to the desired location:
5137
5138	export KBUILD_OUTPUT=/tmp/build
5139	make distclean
5140	make NAME_defconfig
5141	make all
5142
5143Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
5144variable.
5145
5146
5147Please be aware that the Makefiles assume you are using GNU make, so
5148for instance on NetBSD you might need to use "gmake" instead of
5149native "make".
5150
5151
5152If the system board that you have is not listed, then you will need
5153to port U-Boot to your hardware platform. To do this, follow these
5154steps:
5155
51561.  Add a new configuration option for your board to the toplevel
5157    "boards.cfg" file, using the existing entries as examples.
5158    Follow the instructions there to keep the boards in order.
51592.  Create a new directory to hold your board specific code. Add any
5160    files you need. In your board directory, you will need at least
5161    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
51623.  Create a new configuration file "include/configs/<board>.h" for
5163    your board
51643.  If you're porting U-Boot to a new CPU, then also create a new
5165    directory to hold your CPU specific code. Add any files you need.
51664.  Run "make <board>_defconfig" with your new name.
51675.  Type "make", and you should get a working "u-boot.srec" file
5168    to be installed on your target system.
51696.  Debug and solve any problems that might arise.
5170    [Of course, this last step is much harder than it sounds.]
5171
5172
5173Testing of U-Boot Modifications, Ports to New Hardware, etc.:
5174==============================================================
5175
5176If you have modified U-Boot sources (for instance added a new board
5177or support for new devices, a new CPU, etc.) you are expected to
5178provide feedback to the other developers. The feedback normally takes
5179the form of a "patch", i. e. a context diff against a certain (latest
5180official or latest in the git repository) version of U-Boot sources.
5181
5182But before you submit such a patch, please verify that your modifi-
5183cation did not break existing code. At least make sure that *ALL* of
5184the supported boards compile WITHOUT ANY compiler warnings. To do so,
5185just run the "MAKEALL" script, which will configure and build U-Boot
5186for ALL supported system. Be warned, this will take a while. You can
5187select which (cross) compiler to use by passing a `CROSS_COMPILE'
5188environment variable to the script, i. e. to use the ELDK cross tools
5189you can type
5190
5191	CROSS_COMPILE=ppc_8xx- MAKEALL
5192
5193or to build on a native PowerPC system you can type
5194
5195	CROSS_COMPILE=' ' MAKEALL
5196
5197When using the MAKEALL script, the default behaviour is to build
5198U-Boot in the source directory. This location can be changed by
5199setting the BUILD_DIR environment variable. Also, for each target
5200built, the MAKEALL script saves two log files (<target>.ERR and
5201<target>.MAKEALL) in the <source dir>/LOG directory. This default
5202location can be changed by setting the MAKEALL_LOGDIR environment
5203variable. For example:
5204
5205	export BUILD_DIR=/tmp/build
5206	export MAKEALL_LOGDIR=/tmp/log
5207	CROSS_COMPILE=ppc_8xx- MAKEALL
5208
5209With the above settings build objects are saved in the /tmp/build,
5210log files are saved in the /tmp/log and the source tree remains clean
5211during the whole build process.
5212
5213
5214See also "U-Boot Porting Guide" below.
5215
5216
5217Monitor Commands - Overview:
5218============================
5219
5220go	- start application at address 'addr'
5221run	- run commands in an environment variable
5222bootm	- boot application image from memory
5223bootp	- boot image via network using BootP/TFTP protocol
5224bootz   - boot zImage from memory
5225tftpboot- boot image via network using TFTP protocol
5226	       and env variables "ipaddr" and "serverip"
5227	       (and eventually "gatewayip")
5228tftpput - upload a file via network using TFTP protocol
5229rarpboot- boot image via network using RARP/TFTP protocol
5230diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
5231loads	- load S-Record file over serial line
5232loadb	- load binary file over serial line (kermit mode)
5233md	- memory display
5234mm	- memory modify (auto-incrementing)
5235nm	- memory modify (constant address)
5236mw	- memory write (fill)
5237cp	- memory copy
5238cmp	- memory compare
5239crc32	- checksum calculation
5240i2c	- I2C sub-system
5241sspi	- SPI utility commands
5242base	- print or set address offset
5243printenv- print environment variables
5244setenv	- set environment variables
5245saveenv - save environment variables to persistent storage
5246protect - enable or disable FLASH write protection
5247erase	- erase FLASH memory
5248flinfo	- print FLASH memory information
5249nand	- NAND memory operations (see doc/README.nand)
5250bdinfo	- print Board Info structure
5251iminfo	- print header information for application image
5252coninfo - print console devices and informations
5253ide	- IDE sub-system
5254loop	- infinite loop on address range
5255loopw	- infinite write loop on address range
5256mtest	- simple RAM test
5257icache	- enable or disable instruction cache
5258dcache	- enable or disable data cache
5259reset	- Perform RESET of the CPU
5260echo	- echo args to console
5261version - print monitor version
5262help	- print online help
5263?	- alias for 'help'
5264
5265
5266Monitor Commands - Detailed Description:
5267========================================
5268
5269TODO.
5270
5271For now: just type "help <command>".
5272
5273
5274Environment Variables:
5275======================
5276
5277U-Boot supports user configuration using Environment Variables which
5278can be made persistent by saving to Flash memory.
5279
5280Environment Variables are set using "setenv", printed using
5281"printenv", and saved to Flash using "saveenv". Using "setenv"
5282without a value can be used to delete a variable from the
5283environment. As long as you don't save the environment you are
5284working with an in-memory copy. In case the Flash area containing the
5285environment is erased by accident, a default environment is provided.
5286
5287Some configuration options can be set using Environment Variables.
5288
5289List of environment variables (most likely not complete):
5290
5291  baudrate	- see CONFIG_BAUDRATE
5292
5293  bootdelay	- see CONFIG_BOOTDELAY
5294
5295  bootcmd	- see CONFIG_BOOTCOMMAND
5296
5297  bootargs	- Boot arguments when booting an RTOS image
5298
5299  bootfile	- Name of the image to load with TFTP
5300
5301  bootm_low	- Memory range available for image processing in the bootm
5302		  command can be restricted. This variable is given as
5303		  a hexadecimal number and defines lowest address allowed
5304		  for use by the bootm command. See also "bootm_size"
5305		  environment variable. Address defined by "bootm_low" is
5306		  also the base of the initial memory mapping for the Linux
5307		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5308		  bootm_mapsize.
5309
5310  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5311		  This variable is given as a hexadecimal number and it
5312		  defines the size of the memory region starting at base
5313		  address bootm_low that is accessible by the Linux kernel
5314		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5315		  as the default value if it is defined, and bootm_size is
5316		  used otherwise.
5317
5318  bootm_size	- Memory range available for image processing in the bootm
5319		  command can be restricted. This variable is given as
5320		  a hexadecimal number and defines the size of the region
5321		  allowed for use by the bootm command. See also "bootm_low"
5322		  environment variable.
5323
5324  updatefile	- Location of the software update file on a TFTP server, used
5325		  by the automatic software update feature. Please refer to
5326		  documentation in doc/README.update for more details.
5327
5328  autoload	- if set to "no" (any string beginning with 'n'),
5329		  "bootp" will just load perform a lookup of the
5330		  configuration from the BOOTP server, but not try to
5331		  load any image using TFTP
5332
5333  autostart	- if set to "yes", an image loaded using the "bootp",
5334		  "rarpboot", "tftpboot" or "diskboot" commands will
5335		  be automatically started (by internally calling
5336		  "bootm")
5337
5338		  If set to "no", a standalone image passed to the
5339		  "bootm" command will be copied to the load address
5340		  (and eventually uncompressed), but NOT be started.
5341		  This can be used to load and uncompress arbitrary
5342		  data.
5343
5344  fdt_high	- if set this restricts the maximum address that the
5345		  flattened device tree will be copied into upon boot.
5346		  For <