xref: /rk3399_rockchip-uboot/README (revision 98af87997670af840ef178f76b4d6888534a6700)
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 file to find out who contributed
38the specific port. In addition, there are various MAINTAINERS files
39scattered throughout the U-Boot source identifying the people or
40companies responsible for various boards and subsystems.
41
42Note: As of August, 2010, there is no longer a CHANGELOG file in the
43actual U-Boot source tree; however, it can be created dynamically
44from the Git log using:
45
46	make CHANGELOG
47
48
49Where to get help:
50==================
51
52In case you have questions about, problems with or contributions for
53U-Boot, you should send a message to the U-Boot mailing list at
54<u-boot@lists.denx.de>. There is also an archive of previous traffic
55on the mailing list - please search the archive before asking FAQ's.
56Please see http://lists.denx.de/pipermail/u-boot and
57http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
58
59
60Where to get source code:
61=========================
62
63The U-Boot source code is maintained in the Git repository at
64git://www.denx.de/git/u-boot.git ; you can browse it online at
65http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
66
67The "snapshot" links on this page allow you to download tarballs of
68any version you might be interested in. Official releases are also
69available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
70directory.
71
72Pre-built (and tested) images are available from
73ftp://ftp.denx.de/pub/u-boot/images/
74
75
76Where we come from:
77===================
78
79- start from 8xxrom sources
80- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
81- clean up code
82- make it easier to add custom boards
83- make it possible to add other [PowerPC] CPUs
84- extend functions, especially:
85  * Provide extended interface to Linux boot loader
86  * S-Record download
87  * network boot
88  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
89- create ARMBoot project (http://sourceforge.net/projects/armboot)
90- add other CPU families (starting with ARM)
91- create U-Boot project (http://sourceforge.net/projects/u-boot)
92- current project page: see http://www.denx.de/wiki/U-Boot
93
94
95Names and Spelling:
96===================
97
98The "official" name of this project is "Das U-Boot". The spelling
99"U-Boot" shall be used in all written text (documentation, comments
100in source files etc.). Example:
101
102	This is the README file for the U-Boot project.
103
104File names etc. shall be based on the string "u-boot". Examples:
105
106	include/asm-ppc/u-boot.h
107
108	#include <asm/u-boot.h>
109
110Variable names, preprocessor constants etc. shall be either based on
111the string "u_boot" or on "U_BOOT". Example:
112
113	U_BOOT_VERSION		u_boot_logo
114	IH_OS_U_BOOT		u_boot_hush_start
115
116
117Versioning:
118===========
119
120Starting with the release in October 2008, the names of the releases
121were changed from numerical release numbers without deeper meaning
122into a time stamp based numbering. Regular releases are identified by
123names consisting of the calendar year and month of the release date.
124Additional fields (if present) indicate release candidates or bug fix
125releases in "stable" maintenance trees.
126
127Examples:
128	U-Boot v2009.11	    - Release November 2009
129	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
130	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
131
132
133Directory Hierarchy:
134====================
135
136/arch			Architecture specific files
137  /arc			Files generic to ARC architecture
138  /arm			Files generic to ARM architecture
139  /avr32		Files generic to AVR32 architecture
140  /blackfin		Files generic to Analog Devices Blackfin architecture
141  /m68k			Files generic to m68k architecture
142  /microblaze		Files generic to microblaze architecture
143  /mips			Files generic to MIPS architecture
144  /nds32		Files generic to NDS32 architecture
145  /nios2		Files generic to Altera NIOS2 architecture
146  /openrisc		Files generic to OpenRISC architecture
147  /powerpc		Files generic to PowerPC architecture
148  /sandbox		Files generic to HW-independent "sandbox"
149  /sh			Files generic to SH architecture
150  /sparc		Files generic to SPARC architecture
151  /x86			Files generic to x86 architecture
152/api			Machine/arch independent API for external apps
153/board			Board dependent files
154/cmd			U-Boot commands functions
155/common			Misc architecture independent functions
156/configs		Board default configuration files
157/disk			Code for disk drive partition handling
158/doc			Documentation (don't expect too much)
159/drivers		Commonly used device drivers
160/dts			Contains Makefile for building internal U-Boot fdt.
161/examples		Example code for standalone applications, etc.
162/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
163/include		Header Files
164/lib			Library routines generic to all architectures
165/Licenses		Various license files
166/net			Networking code
167/post			Power On Self Test
168/scripts		Various build scripts and Makefiles
169/test			Various unit test files
170/tools			Tools to build S-Record or U-Boot images, etc.
171
172Software Configuration:
173=======================
174
175Configuration is usually done using C preprocessor defines; the
176rationale behind that is to avoid dead code whenever possible.
177
178There are two classes of configuration variables:
179
180* Configuration _OPTIONS_:
181  These are selectable by the user and have names beginning with
182  "CONFIG_".
183
184* Configuration _SETTINGS_:
185  These depend on the hardware etc. and should not be meddled with if
186  you don't know what you're doing; they have names beginning with
187  "CONFIG_SYS_".
188
189Previously, all configuration was done by hand, which involved creating
190symbolic links and editing configuration files manually. More recently,
191U-Boot has added the Kbuild infrastructure used by the Linux kernel,
192allowing you to use the "make menuconfig" command to configure your
193build.
194
195
196Selection of Processor Architecture and Board Type:
197---------------------------------------------------
198
199For all supported boards there are ready-to-use default
200configurations available; just type "make <board_name>_defconfig".
201
202Example: For a TQM823L module type:
203
204	cd u-boot
205	make TQM823L_defconfig
206
207Note: If you're looking for the default configuration file for a board
208you're sure used to be there but is now missing, check the file
209doc/README.scrapyard for a list of no longer supported boards.
210
211Sandbox Environment:
212--------------------
213
214U-Boot can be built natively to run on a Linux host using the 'sandbox'
215board. This allows feature development which is not board- or architecture-
216specific to be undertaken on a native platform. The sandbox is also used to
217run some of U-Boot's tests.
218
219See board/sandbox/README.sandbox for more details.
220
221
222Board Initialisation Flow:
223--------------------------
224
225This is the intended start-up flow for boards. This should apply for both
226SPL and U-Boot proper (i.e. they both follow the same rules).
227
228Note: "SPL" stands for "Secondary Program Loader," which is explained in
229more detail later in this file.
230
231At present, SPL mostly uses a separate code path, but the function names
232and roles of each function are the same. Some boards or architectures
233may not conform to this.  At least most ARM boards which use
234CONFIG_SPL_FRAMEWORK conform to this.
235
236Execution typically starts with an architecture-specific (and possibly
237CPU-specific) start.S file, such as:
238
239	- arch/arm/cpu/armv7/start.S
240	- arch/powerpc/cpu/mpc83xx/start.S
241	- arch/mips/cpu/start.S
242
243and so on. From there, three functions are called; the purpose and
244limitations of each of these functions are described below.
245
246lowlevel_init():
247	- purpose: essential init to permit execution to reach board_init_f()
248	- no global_data or BSS
249	- there is no stack (ARMv7 may have one but it will soon be removed)
250	- must not set up SDRAM or use console
251	- must only do the bare minimum to allow execution to continue to
252		board_init_f()
253	- this is almost never needed
254	- return normally from this function
255
256board_init_f():
257	- purpose: set up the machine ready for running board_init_r():
258		i.e. SDRAM and serial UART
259	- global_data is available
260	- stack is in SRAM
261	- BSS is not available, so you cannot use global/static variables,
262		only stack variables and global_data
263
264	Non-SPL-specific notes:
265	- dram_init() is called to set up DRAM. If already done in SPL this
266		can do nothing
267
268	SPL-specific notes:
269	- you can override the entire board_init_f() function with your own
270		version as needed.
271	- preloader_console_init() can be called here in extremis
272	- should set up SDRAM, and anything needed to make the UART work
273	- these is no need to clear BSS, it will be done by crt0.S
274	- must return normally from this function (don't call board_init_r()
275		directly)
276
277Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
278this point the stack and global_data are relocated to below
279CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
280memory.
281
282board_init_r():
283	- purpose: main execution, common code
284	- global_data is available
285	- SDRAM is available
286	- BSS is available, all static/global variables can be used
287	- execution eventually continues to main_loop()
288
289	Non-SPL-specific notes:
290	- U-Boot is relocated to the top of memory and is now running from
291		there.
292
293	SPL-specific notes:
294	- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
295		CONFIG_SPL_STACK_R_ADDR points into SDRAM
296	- preloader_console_init() can be called here - typically this is
297		done by defining CONFIG_SPL_BOARD_INIT and then supplying a
298		spl_board_init() function containing this call
299	- loads U-Boot or (in falcon mode) Linux
300
301
302
303Configuration Options:
304----------------------
305
306Configuration depends on the combination of board and CPU type; all
307such information is kept in a configuration file
308"include/configs/<board_name>.h".
309
310Example: For a TQM823L module, all configuration settings are in
311"include/configs/TQM823L.h".
312
313
314Many of the options are named exactly as the corresponding Linux
315kernel configuration options. The intention is to make it easier to
316build a config tool - later.
317
318
319The following options need to be configured:
320
321- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
322
323- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
324
325- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
326		Define exactly one, e.g. CONFIG_ATSTK1002
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- 8xx CPU Options: (if using an MPC8xx CPU)
334		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
335					  get_gclk_freq() cannot work
336					  e.g. if there is no 32KHz
337					  reference PIT/RTC clock
338		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
339					  or XTAL/EXTAL)
340
341- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
342		CONFIG_SYS_8xx_CPUCLK_MIN
343		CONFIG_SYS_8xx_CPUCLK_MAX
344		CONFIG_8xx_CPUCLK_DEFAULT
345			See doc/README.MPC866
346
347		CONFIG_SYS_MEASURE_CPUCLK
348
349		Define this to measure the actual CPU clock instead
350		of relying on the correctness of the configured
351		values. Mostly useful for board bringup to make sure
352		the PLL is locked at the intended frequency. Note
353		that this requires a (stable) reference clock (32 kHz
354		RTC clock or CONFIG_SYS_8XX_XIN)
355
356		CONFIG_SYS_DELAYED_ICACHE
357
358		Define this option if you want to enable the
359		ICache only when Code runs from RAM.
360
361- 85xx CPU Options:
362		CONFIG_SYS_PPC64
363
364		Specifies that the core is a 64-bit PowerPC implementation (implements
365		the "64" category of the Power ISA). This is necessary for ePAPR
366		compliance, among other possible reasons.
367
368		CONFIG_SYS_FSL_TBCLK_DIV
369
370		Defines the core time base clock divider ratio compared to the
371		system clock.  On most PQ3 devices this is 8, on newer QorIQ
372		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
373
374		CONFIG_SYS_FSL_PCIE_COMPAT
375
376		Defines the string to utilize when trying to match PCIe device
377		tree nodes for the given platform.
378
379		CONFIG_SYS_PPC_E500_DEBUG_TLB
380
381		Enables a temporary TLB entry to be used during boot to work
382		around limitations in e500v1 and e500v2 external debugger
383		support. This reduces the portions of the boot code where
384		breakpoints and single stepping do not work.  The value of this
385		symbol should be set to the TLB1 entry to be used for this
386		purpose.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510
389
390		Enables a workaround for erratum A004510.  If set,
391		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
392		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
393
394		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
395		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
396
397		Defines one or two SoC revisions (low 8 bits of SVR)
398		for which the A004510 workaround should be applied.
399
400		The rest of SVR is either not relevant to the decision
401		of whether the erratum is present (e.g. p2040 versus
402		p2041) or is implied by the build target, which controls
403		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
404
405		See Freescale App Note 4493 for more information about
406		this erratum.
407
408		CONFIG_A003399_NOR_WORKAROUND
409		Enables a workaround for IFC erratum A003399. It is only
410		required during NOR boot.
411
412		CONFIG_A008044_WORKAROUND
413		Enables a workaround for T1040/T1042 erratum A008044. It is only
414		required during NAND boot and valid for Rev 1.0 SoC revision
415
416		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
417
418		This is the value to write into CCSR offset 0x18600
419		according to the A004510 workaround.
420
421		CONFIG_SYS_FSL_DSP_DDR_ADDR
422		This value denotes start offset of DDR memory which is
423		connected exclusively to the DSP cores.
424
425		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
426		This value denotes start offset of M2 memory
427		which is directly connected to the DSP core.
428
429		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
430		This value denotes start offset of M3 memory which is directly
431		connected to the DSP core.
432
433		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
434		This value denotes start offset of DSP CCSR space.
435
436		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
437		Single Source Clock is clocking mode present in some of FSL SoC's.
438		In this mode, a single differential clock is used to supply
439		clocks to the sysclock, ddrclock and usbclock.
440
441		CONFIG_SYS_CPC_REINIT_F
442		This CONFIG is defined when the CPC is configured as SRAM at the
443		time of U-Boot entry and is required to be re-initialized.
444
445		CONFIG_DEEP_SLEEP
446		Indicates this SoC supports deep sleep feature. If deep sleep is
447		supported, core will start to execute uboot when wakes up.
448
449- Generic CPU options:
450		CONFIG_SYS_GENERIC_GLOBAL_DATA
451		Defines global data is initialized in generic board board_init_f().
452		If this macro is defined, global data is created and cleared in
453		generic board board_init_f(). Without this macro, architecture/board
454		should initialize global data before calling board_init_f().
455
456		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
457
458		Defines the endianess of the CPU. Implementation of those
459		values is arch specific.
460
461		CONFIG_SYS_FSL_DDR
462		Freescale DDR driver in use. This type of DDR controller is
463		found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core
464		SoCs.
465
466		CONFIG_SYS_FSL_DDR_ADDR
467		Freescale DDR memory-mapped register base.
468
469		CONFIG_SYS_FSL_DDR_EMU
470		Specify emulator support for DDR. Some DDR features such as
471		deskew training are not available.
472
473		CONFIG_SYS_FSL_DDRC_GEN1
474		Freescale DDR1 controller.
475
476		CONFIG_SYS_FSL_DDRC_GEN2
477		Freescale DDR2 controller.
478
479		CONFIG_SYS_FSL_DDRC_GEN3
480		Freescale DDR3 controller.
481
482		CONFIG_SYS_FSL_DDRC_GEN4
483		Freescale DDR4 controller.
484
485		CONFIG_SYS_FSL_DDRC_ARM_GEN3
486		Freescale DDR3 controller for ARM-based SoCs.
487
488		CONFIG_SYS_FSL_DDR1
489		Board config to use DDR1. It can be enabled for SoCs with
490		Freescale DDR1 or DDR2 controllers, depending on the board
491		implemetation.
492
493		CONFIG_SYS_FSL_DDR2
494		Board config to use DDR2. It can be enabled for SoCs with
495		Freescale DDR2 or DDR3 controllers, depending on the board
496		implementation.
497
498		CONFIG_SYS_FSL_DDR3
499		Board config to use DDR3. It can be enabled for SoCs with
500		Freescale DDR3 or DDR3L controllers.
501
502		CONFIG_SYS_FSL_DDR3L
503		Board config to use DDR3L. It can be enabled for SoCs with
504		DDR3L controllers.
505
506		CONFIG_SYS_FSL_DDR4
507		Board config to use DDR4. It can be enabled for SoCs with
508		DDR4 controllers.
509
510		CONFIG_SYS_FSL_IFC_BE
511		Defines the IFC controller register space as Big Endian
512
513		CONFIG_SYS_FSL_IFC_LE
514		Defines the IFC controller register space as Little Endian
515
516		CONFIG_SYS_FSL_PBL_PBI
517		It enables addition of RCW (Power on reset configuration) in built image.
518		Please refer doc/README.pblimage for more details
519
520		CONFIG_SYS_FSL_PBL_RCW
521		It adds PBI(pre-boot instructions) commands in u-boot build image.
522		PBI commands can be used to configure SoC before it starts the execution.
523		Please refer doc/README.pblimage for more details
524
525		CONFIG_SPL_FSL_PBL
526		It adds a target to create boot binary having SPL binary in PBI format
527		concatenated with u-boot binary.
528
529		CONFIG_SYS_FSL_DDR_BE
530		Defines the DDR controller register space as Big Endian
531
532		CONFIG_SYS_FSL_DDR_LE
533		Defines the DDR controller register space as Little Endian
534
535		CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
536		Physical address from the view of DDR controllers. It is the
537		same as CONFIG_SYS_DDR_SDRAM_BASE for  all Power SoCs. But
538		it could be different for ARM SoCs.
539
540		CONFIG_SYS_FSL_DDR_INTLV_256B
541		DDR controller interleaving on 256-byte. This is a special
542		interleaving mode, handled by Dickens for Freescale layerscape
543		SoCs with ARM core.
544
545		CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
546		Number of controllers used as main memory.
547
548		CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
549		Number of controllers used for other than main memory.
550
551		CONFIG_SYS_FSL_HAS_DP_DDR
552		Defines the SoC has DP-DDR used for DPAA.
553
554		CONFIG_SYS_FSL_SEC_BE
555		Defines the SEC controller register space as Big Endian
556
557		CONFIG_SYS_FSL_SEC_LE
558		Defines the SEC controller register space as Little Endian
559
560- MIPS CPU options:
561		CONFIG_SYS_INIT_SP_OFFSET
562
563		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
564		pointer. This is needed for the temporary stack before
565		relocation.
566
567		CONFIG_SYS_MIPS_CACHE_MODE
568
569		Cache operation mode for the MIPS CPU.
570		See also arch/mips/include/asm/mipsregs.h.
571		Possible values are:
572			CONF_CM_CACHABLE_NO_WA
573			CONF_CM_CACHABLE_WA
574			CONF_CM_UNCACHED
575			CONF_CM_CACHABLE_NONCOHERENT
576			CONF_CM_CACHABLE_CE
577			CONF_CM_CACHABLE_COW
578			CONF_CM_CACHABLE_CUW
579			CONF_CM_CACHABLE_ACCELERATED
580
581		CONFIG_SYS_XWAY_EBU_BOOTCFG
582
583		Special option for Lantiq XWAY SoCs for booting from NOR flash.
584		See also arch/mips/cpu/mips32/start.S.
585
586		CONFIG_XWAY_SWAP_BYTES
587
588		Enable compilation of tools/xway-swap-bytes needed for Lantiq
589		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
590		be swapped if a flash programmer is used.
591
592- ARM options:
593		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
594
595		Select high exception vectors of the ARM core, e.g., do not
596		clear the V bit of the c1 register of CP15.
597
598		CONFIG_SYS_THUMB_BUILD
599
600		Use this flag to build U-Boot using the Thumb instruction
601		set for ARM architectures. Thumb instruction set provides
602		better code density. For ARM architectures that support
603		Thumb2 this flag will result in Thumb2 code generated by
604		GCC.
605
606		CONFIG_ARM_ERRATA_716044
607		CONFIG_ARM_ERRATA_742230
608		CONFIG_ARM_ERRATA_743622
609		CONFIG_ARM_ERRATA_751472
610		CONFIG_ARM_ERRATA_761320
611		CONFIG_ARM_ERRATA_773022
612		CONFIG_ARM_ERRATA_774769
613		CONFIG_ARM_ERRATA_794072
614
615		If set, the workarounds for these ARM errata are applied early
616		during U-Boot startup. Note that these options force the
617		workarounds to be applied; no CPU-type/version detection
618		exists, unlike the similar options in the Linux kernel. Do not
619		set these options unless they apply!
620
621		COUNTER_FREQUENCY
622		Generic timer clock source frequency.
623
624		COUNTER_FREQUENCY_REAL
625		Generic timer clock source frequency if the real clock is
626		different from COUNTER_FREQUENCY, and can only be determined
627		at run time.
628
629		NOTE: The following can be machine specific errata. These
630		do have ability to provide rudimentary version and machine
631		specific checks, but expect no product checks.
632		CONFIG_ARM_ERRATA_430973
633		CONFIG_ARM_ERRATA_454179
634		CONFIG_ARM_ERRATA_621766
635		CONFIG_ARM_ERRATA_798870
636		CONFIG_ARM_ERRATA_801819
637
638- Tegra SoC options:
639		CONFIG_TEGRA_SUPPORT_NON_SECURE
640
641		Support executing U-Boot in non-secure (NS) mode. Certain
642		impossible actions will be skipped if the CPU is in NS mode,
643		such as ARM architectural timer initialization.
644
645- Linux Kernel Interface:
646		CONFIG_CLOCKS_IN_MHZ
647
648		U-Boot stores all clock information in Hz
649		internally. For binary compatibility with older Linux
650		kernels (which expect the clocks passed in the
651		bd_info data to be in MHz) the environment variable
652		"clocks_in_mhz" can be defined so that U-Boot
653		converts clock data to MHZ before passing it to the
654		Linux kernel.
655		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
656		"clocks_in_mhz=1" is automatically included in the
657		default environment.
658
659		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
660
661		When transferring memsize parameter to Linux, some versions
662		expect it to be in bytes, others in MB.
663		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
664
665		CONFIG_OF_LIBFDT
666
667		New kernel versions are expecting firmware settings to be
668		passed using flattened device trees (based on open firmware
669		concepts).
670
671		CONFIG_OF_LIBFDT
672		 * New libfdt-based support
673		 * Adds the "fdt" command
674		 * The bootm command automatically updates the fdt
675
676		OF_CPU - The proper name of the cpus node (only required for
677			MPC512X and MPC5xxx based boards).
678		OF_SOC - The proper name of the soc node (only required for
679			MPC512X and MPC5xxx based boards).
680		OF_TBCLK - The timebase frequency.
681		OF_STDOUT_PATH - The path to the console device
682
683		boards with QUICC Engines require OF_QE to set UCC MAC
684		addresses
685
686		CONFIG_OF_BOARD_SETUP
687
688		Board code has addition modification that it wants to make
689		to the flat device tree before handing it off to the kernel
690
691		CONFIG_OF_SYSTEM_SETUP
692
693		Other code has addition modification that it wants to make
694		to the flat device tree before handing it off to the kernel.
695		This causes ft_system_setup() to be called before booting
696		the kernel.
697
698		CONFIG_OF_IDE_FIXUP
699
700		U-Boot can detect if an IDE device is present or not.
701		If not, and this new config option is activated, U-Boot
702		removes the ATA node from the DTS before booting Linux,
703		so the Linux IDE driver does not probe the device and
704		crash. This is needed for buggy hardware (uc101) where
705		no pull down resistor is connected to the signal IDE5V_DD7.
706
707		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
708
709		This setting is mandatory for all boards that have only one
710		machine type and must be used to specify the machine type
711		number as it appears in the ARM machine registry
712		(see http://www.arm.linux.org.uk/developer/machines/).
713		Only boards that have multiple machine types supported
714		in a single configuration file and the machine type is
715		runtime discoverable, do not have to use this setting.
716
717- vxWorks boot parameters:
718
719		bootvx constructs a valid bootline using the following
720		environments variables: bootdev, bootfile, ipaddr, netmask,
721		serverip, gatewayip, hostname, othbootargs.
722		It loads the vxWorks image pointed bootfile.
723
724		Note: If a "bootargs" environment is defined, it will overwride
725		the defaults discussed just above.
726
727- Cache Configuration:
728		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
729		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
730		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
731
732- Cache Configuration for ARM:
733		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
734				      controller
735		CONFIG_SYS_PL310_BASE - Physical base address of PL310
736					controller register space
737
738- Serial Ports:
739		CONFIG_PL010_SERIAL
740
741		Define this if you want support for Amba PrimeCell PL010 UARTs.
742
743		CONFIG_PL011_SERIAL
744
745		Define this if you want support for Amba PrimeCell PL011 UARTs.
746
747		CONFIG_PL011_CLOCK
748
749		If you have Amba PrimeCell PL011 UARTs, set this variable to
750		the clock speed of the UARTs.
751
752		CONFIG_PL01x_PORTS
753
754		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
755		define this to a list of base addresses for each (supported)
756		port. See e.g. include/configs/versatile.h
757
758		CONFIG_SERIAL_HW_FLOW_CONTROL
759
760		Define this variable to enable hw flow control in serial driver.
761		Current user of this option is drivers/serial/nsl16550.c driver
762
763- Console Interface:
764		Depending on board, define exactly one serial port
765		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
766		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
767		console by defining CONFIG_8xx_CONS_NONE
768
769		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
770		port routines must be defined elsewhere
771		(i.e. serial_init(), serial_getc(), ...)
772
773		CONFIG_CFB_CONSOLE
774		Enables console device for a color framebuffer. Needs following
775		defines (cf. smiLynxEM, i8042)
776			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
777						(default big endian)
778			VIDEO_HW_RECTFILL	graphic chip supports
779						rectangle fill
780						(cf. smiLynxEM)
781			VIDEO_HW_BITBLT		graphic chip supports
782						bit-blit (cf. smiLynxEM)
783			VIDEO_VISIBLE_COLS	visible pixel columns
784						(cols=pitch)
785			VIDEO_VISIBLE_ROWS	visible pixel rows
786			VIDEO_PIXEL_SIZE	bytes per pixel
787			VIDEO_DATA_FORMAT	graphic data format
788						(0-5, cf. cfb_console.c)
789			VIDEO_FB_ADRS		framebuffer address
790			VIDEO_KBD_INIT_FCT	keyboard int fct
791						(i.e. rx51_kp_init())
792			VIDEO_TSTC_FCT		test char fct
793						(i.e. rx51_kp_tstc)
794			VIDEO_GETC_FCT		get char fct
795						(i.e. rx51_kp_getc)
796			CONFIG_VIDEO_LOGO	display Linux logo in
797						upper left corner
798			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
799						linux_logo.h for logo.
800						Requires CONFIG_VIDEO_LOGO
801			CONFIG_CONSOLE_EXTRA_INFO
802						additional board info beside
803						the logo
804			CONFIG_HIDE_LOGO_VERSION
805						do not display bootloader
806						version string
807
808		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
809		a limited number of ANSI escape sequences (cursor control,
810		erase functions and limited graphics rendition control).
811
812		When CONFIG_CFB_CONSOLE is defined, video console is
813		default i/o. Serial console can be forced with
814		environment 'console=serial'.
815
816		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
817			is 0x00.
818		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
819			is 0xa0.
820
821- Console Baudrate:
822		CONFIG_BAUDRATE - in bps
823		Select one of the baudrates listed in
824		CONFIG_SYS_BAUDRATE_TABLE, see below.
825		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
826
827- Console Rx buffer length
828		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
829		the maximum receive buffer length for the SMC.
830		This option is actual only for 82xx and 8xx possible.
831		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
832		must be defined, to setup the maximum idle timeout for
833		the SMC.
834
835- Pre-Console Buffer:
836		Prior to the console being initialised (i.e. serial UART
837		initialised etc) all console output is silently discarded.
838		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
839		buffer any console messages prior to the console being
840		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
841		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
842		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
843		bytes are output before the console is initialised, the
844		earlier bytes are discarded.
845
846		Note that when printing the buffer a copy is made on the
847		stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack.
848
849		'Sane' compilers will generate smaller code if
850		CONFIG_PRE_CON_BUF_SZ is a power of 2
851
852- Autoboot Command:
853		CONFIG_BOOTCOMMAND
854		Only needed when CONFIG_BOOTDELAY is enabled;
855		define a command string that is automatically executed
856		when no character is read on the console interface
857		within "Boot Delay" after reset.
858
859		CONFIG_BOOTARGS
860		This can be used to pass arguments to the bootm
861		command. The value of CONFIG_BOOTARGS goes into the
862		environment value "bootargs".
863
864		CONFIG_RAMBOOT and CONFIG_NFSBOOT
865		The value of these goes into the environment as
866		"ramboot" and "nfsboot" respectively, and can be used
867		as a convenience, when switching between booting from
868		RAM and NFS.
869
870- Bootcount:
871		CONFIG_BOOTCOUNT_LIMIT
872		Implements a mechanism for detecting a repeating reboot
873		cycle, see:
874		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
875
876		CONFIG_BOOTCOUNT_ENV
877		If no softreset save registers are found on the hardware
878		"bootcount" is stored in the environment. To prevent a
879		saveenv on all reboots, the environment variable
880		"upgrade_available" is used. If "upgrade_available" is
881		0, "bootcount" is always 0, if "upgrade_available" is
882		1 "bootcount" is incremented in the environment.
883		So the Userspace Applikation must set the "upgrade_available"
884		and "bootcount" variable to 0, if a boot was successfully.
885
886- Pre-Boot Commands:
887		CONFIG_PREBOOT
888
889		When this option is #defined, the existence of the
890		environment variable "preboot" will be checked
891		immediately before starting the CONFIG_BOOTDELAY
892		countdown and/or running the auto-boot command resp.
893		entering interactive mode.
894
895		This feature is especially useful when "preboot" is
896		automatically generated or modified. For an example
897		see the LWMON board specific code: here "preboot" is
898		modified when the user holds down a certain
899		combination of keys on the (special) keyboard when
900		booting the systems
901
902- Serial Download Echo Mode:
903		CONFIG_LOADS_ECHO
904		If defined to 1, all characters received during a
905		serial download (using the "loads" command) are
906		echoed back. This might be needed by some terminal
907		emulations (like "cu"), but may as well just take
908		time on others. This setting #define's the initial
909		value of the "loads_echo" environment variable.
910
911- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
912		CONFIG_KGDB_BAUDRATE
913		Select one of the baudrates listed in
914		CONFIG_SYS_BAUDRATE_TABLE, see below.
915
916- Monitor Functions:
917		Monitor commands can be included or excluded
918		from the build by using the #include files
919		<config_cmd_all.h> and #undef'ing unwanted
920		commands, or adding #define's for wanted commands.
921
922		The default command configuration includes all commands
923		except those marked below with a "*".
924
925		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
926		CONFIG_CMD_ASKENV	* ask for env variable
927		CONFIG_CMD_BDI		  bdinfo
928		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
929		CONFIG_CMD_BMP		* BMP support
930		CONFIG_CMD_BSP		* Board specific commands
931		CONFIG_CMD_BOOTD	  bootd
932		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
933		CONFIG_CMD_CACHE	* icache, dcache
934		CONFIG_CMD_CLK   	* clock command support
935		CONFIG_CMD_CONSOLE	  coninfo
936		CONFIG_CMD_CRC32	* crc32
937		CONFIG_CMD_DATE		* support for RTC, date/time...
938		CONFIG_CMD_DHCP		* DHCP support
939		CONFIG_CMD_DIAG		* Diagnostics
940		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
941		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
942		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
943		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
944		CONFIG_CMD_DTT		* Digital Therm and Thermostat
945		CONFIG_CMD_ECHO		  echo arguments
946		CONFIG_CMD_EDITENV	  edit env variable
947		CONFIG_CMD_EEPROM	* EEPROM read/write support
948		CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands
949		CONFIG_CMD_ELF		* bootelf, bootvx
950		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
951		CONFIG_CMD_ENV_FLAGS	* display details about env flags
952		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
953		CONFIG_CMD_EXPORTENV	* export the environment
954		CONFIG_CMD_EXT2		* ext2 command support
955		CONFIG_CMD_EXT4		* ext4 command support
956		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
957					  that work for multiple fs types
958		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
959		CONFIG_CMD_SAVEENV	  saveenv
960		CONFIG_CMD_FDC		* Floppy Disk Support
961		CONFIG_CMD_FAT		* FAT command support
962		CONFIG_CMD_FLASH	  flinfo, erase, protect
963		CONFIG_CMD_FPGA		  FPGA device initialization support
964		CONFIG_CMD_FUSE		* Device fuse support
965		CONFIG_CMD_GETTIME	* Get time since boot
966		CONFIG_CMD_GO		* the 'go' command (exec code)
967		CONFIG_CMD_GREPENV	* search environment
968		CONFIG_CMD_HASH		* calculate hash / digest
969		CONFIG_CMD_I2C		* I2C serial bus support
970		CONFIG_CMD_IDE		* IDE harddisk support
971		CONFIG_CMD_IMI		  iminfo
972		CONFIG_CMD_IMLS		  List all images found in NOR flash
973		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
974		CONFIG_CMD_IMMAP	* IMMR dump support
975		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
976		CONFIG_CMD_IMPORTENV	* import an environment
977		CONFIG_CMD_INI		* import data from an ini file into the env
978		CONFIG_CMD_IRQ		* irqinfo
979		CONFIG_CMD_ITEST	  Integer/string test of 2 values
980		CONFIG_CMD_JFFS2	* JFFS2 Support
981		CONFIG_CMD_KGDB		* kgdb
982		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
983		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
984					  (169.254.*.*)
985		CONFIG_CMD_LOADB	  loadb
986		CONFIG_CMD_LOADS	  loads
987		CONFIG_CMD_MD5SUM	* print md5 message digest
988					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
989		CONFIG_CMD_MEMINFO	* Display detailed memory information
990		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
991					  loop, loopw
992		CONFIG_CMD_MEMTEST	* mtest
993		CONFIG_CMD_MISC		  Misc functions like sleep etc
994		CONFIG_CMD_MMC		* MMC memory mapped support
995		CONFIG_CMD_MII		* MII utility commands
996		CONFIG_CMD_MTDPARTS	* MTD partition support
997		CONFIG_CMD_NAND		* NAND support
998		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
999		CONFIG_CMD_NFS		  NFS support
1000		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
1001		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
1002		CONFIG_CMD_PCI		* pciinfo
1003		CONFIG_CMD_PCMCIA		* PCMCIA support
1004		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
1005					  host
1006		CONFIG_CMD_PORTIO	* Port I/O
1007		CONFIG_CMD_READ		* Read raw data from partition
1008		CONFIG_CMD_REGINFO	* Register dump
1009		CONFIG_CMD_RUN		  run command in env variable
1010		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
1011		CONFIG_CMD_SAVES	* save S record dump
1012		CONFIG_SCSI		* SCSI Support
1013		CONFIG_CMD_SDRAM	* print SDRAM configuration information
1014					  (requires CONFIG_CMD_I2C)
1015		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
1016					  (4xx only)
1017		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1018		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1019					  (requires CONFIG_CMD_MEMORY)
1020		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1021		CONFIG_CMD_SOURCE	  "source" command Support
1022		CONFIG_CMD_SPI		* SPI serial bus support
1023		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1024		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1025		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1026		CONFIG_CMD_TIMER	* access to the system tick timer
1027		CONFIG_CMD_USB		* USB support
1028		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1029		CONFIG_CMD_MFSL		* Microblaze FSL support
1030		CONFIG_CMD_XIMG		  Load part of Multi Image
1031		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1032
1033		EXAMPLE: If you want all functions except of network
1034		support you can write:
1035
1036		#include "config_cmd_all.h"
1037		#undef CONFIG_CMD_NET
1038
1039	Other Commands:
1040		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1041
1042	Note:	Don't enable the "icache" and "dcache" commands
1043		(configuration option CONFIG_CMD_CACHE) unless you know
1044		what you (and your U-Boot users) are doing. Data
1045		cache cannot be enabled on systems like the 8xx or
1046		8260 (where accesses to the IMMR region must be
1047		uncached), and it cannot be disabled on all other
1048		systems where we (mis-) use the data cache to hold an
1049		initial stack and some data.
1050
1051
1052		XXX - this list needs to get updated!
1053
1054- Removal of commands
1055		If no commands are needed to boot, you can disable
1056		CONFIG_CMDLINE to remove them. In this case, the command line
1057		will not be available, and when U-Boot wants to execute the
1058		boot command (on start-up) it will call board_run_command()
1059		instead. This can reduce image size significantly for very
1060		simple boot procedures.
1061
1062- Regular expression support:
1063		CONFIG_REGEX
1064		If this variable is defined, U-Boot is linked against
1065		the SLRE (Super Light Regular Expression) library,
1066		which adds regex support to some commands, as for
1067		example "env grep" and "setexpr".
1068
1069- Device tree:
1070		CONFIG_OF_CONTROL
1071		If this variable is defined, U-Boot will use a device tree
1072		to configure its devices, instead of relying on statically
1073		compiled #defines in the board file. This option is
1074		experimental and only available on a few boards. The device
1075		tree is available in the global data as gd->fdt_blob.
1076
1077		U-Boot needs to get its device tree from somewhere. This can
1078		be done using one of the two options below:
1079
1080		CONFIG_OF_EMBED
1081		If this variable is defined, U-Boot will embed a device tree
1082		binary in its image. This device tree file should be in the
1083		board directory and called <soc>-<board>.dts. The binary file
1084		is then picked up in board_init_f() and made available through
1085		the global data structure as gd->blob.
1086
1087		CONFIG_OF_SEPARATE
1088		If this variable is defined, U-Boot will build a device tree
1089		binary. It will be called u-boot.dtb. Architecture-specific
1090		code will locate it at run-time. Generally this works by:
1091
1092			cat u-boot.bin u-boot.dtb >image.bin
1093
1094		and in fact, U-Boot does this for you, creating a file called
1095		u-boot-dtb.bin which is useful in the common case. You can
1096		still use the individual files if you need something more
1097		exotic.
1098
1099- Watchdog:
1100		CONFIG_WATCHDOG
1101		If this variable is defined, it enables watchdog
1102		support for the SoC. There must be support in the SoC
1103		specific code for a watchdog. For the 8xx and 8260
1104		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1105		register.  When supported for a specific SoC is
1106		available, then no further board specific code should
1107		be needed to use it.
1108
1109		CONFIG_HW_WATCHDOG
1110		When using a watchdog circuitry external to the used
1111		SoC, then define this variable and provide board
1112		specific code for the "hw_watchdog_reset" function.
1113
1114		CONFIG_AT91_HW_WDT_TIMEOUT
1115		specify the timeout in seconds. default 2 seconds.
1116
1117- U-Boot Version:
1118		CONFIG_VERSION_VARIABLE
1119		If this variable is defined, an environment variable
1120		named "ver" is created by U-Boot showing the U-Boot
1121		version as printed by the "version" command.
1122		Any change to this variable will be reverted at the
1123		next reset.
1124
1125- Real-Time Clock:
1126
1127		When CONFIG_CMD_DATE is selected, the type of the RTC
1128		has to be selected, too. Define exactly one of the
1129		following options:
1130
1131		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1132		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1133		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1134		CONFIG_RTC_MC146818	- use MC146818 RTC
1135		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1136		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1137		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1138		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1139		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1140		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1141		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1142		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1143		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1144					  RV3029 RTC.
1145
1146		Note that if the RTC uses I2C, then the I2C interface
1147		must also be configured. See I2C Support, below.
1148
1149- GPIO Support:
1150		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1151
1152		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1153		chip-ngpio pairs that tell the PCA953X driver the number of
1154		pins supported by a particular chip.
1155
1156		Note that if the GPIO device uses I2C, then the I2C interface
1157		must also be configured. See I2C Support, below.
1158
1159- I/O tracing:
1160		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1161		accesses and can checksum them or write a list of them out
1162		to memory. See the 'iotrace' command for details. This is
1163		useful for testing device drivers since it can confirm that
1164		the driver behaves the same way before and after a code
1165		change. Currently this is supported on sandbox and arm. To
1166		add support for your architecture, add '#include <iotrace.h>'
1167		to the bottom of arch/<arch>/include/asm/io.h and test.
1168
1169		Example output from the 'iotrace stats' command is below.
1170		Note that if the trace buffer is exhausted, the checksum will
1171		still continue to operate.
1172
1173			iotrace is enabled
1174			Start:  10000000	(buffer start address)
1175			Size:   00010000	(buffer size)
1176			Offset: 00000120	(current buffer offset)
1177			Output: 10000120	(start + offset)
1178			Count:  00000018	(number of trace records)
1179			CRC32:  9526fb66	(CRC32 of all trace records)
1180
1181- Timestamp Support:
1182
1183		When CONFIG_TIMESTAMP is selected, the timestamp
1184		(date and time) of an image is printed by image
1185		commands like bootm or iminfo. This option is
1186		automatically enabled when you select CONFIG_CMD_DATE .
1187
1188- Partition Labels (disklabels) Supported:
1189		Zero or more of the following:
1190		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1191		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1192				       Intel architecture, USB sticks, etc.
1193		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1194		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1195				       bootloader.  Note 2TB partition limit; see
1196				       disk/part_efi.c
1197		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1198
1199		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1200		CONFIG_SCSI) you must configure support for at
1201		least one non-MTD partition type as well.
1202
1203- IDE Reset method:
1204		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1205		board configurations files but used nowhere!
1206
1207		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1208		be performed by calling the function
1209			ide_set_reset(int reset)
1210		which has to be defined in a board specific file
1211
1212- ATAPI Support:
1213		CONFIG_ATAPI
1214
1215		Set this to enable ATAPI support.
1216
1217- LBA48 Support
1218		CONFIG_LBA48
1219
1220		Set this to enable support for disks larger than 137GB
1221		Also look at CONFIG_SYS_64BIT_LBA.
1222		Whithout these , LBA48 support uses 32bit variables and will 'only'
1223		support disks up to 2.1TB.
1224
1225		CONFIG_SYS_64BIT_LBA:
1226			When enabled, makes the IDE subsystem use 64bit sector addresses.
1227			Default is 32bit.
1228
1229- SCSI Support:
1230		At the moment only there is only support for the
1231		SYM53C8XX SCSI controller; define
1232		CONFIG_SCSI_SYM53C8XX to enable it.
1233
1234		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1235		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1236		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1237		maximum numbers of LUNs, SCSI ID's and target
1238		devices.
1239		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1240
1241		The environment variable 'scsidevs' is set to the number of
1242		SCSI devices found during the last scan.
1243
1244- NETWORK Support (PCI):
1245		CONFIG_E1000
1246		Support for Intel 8254x/8257x gigabit chips.
1247
1248		CONFIG_E1000_SPI
1249		Utility code for direct access to the SPI bus on Intel 8257x.
1250		This does not do anything useful unless you set at least one
1251		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1252
1253		CONFIG_E1000_SPI_GENERIC
1254		Allow generic access to the SPI bus on the Intel 8257x, for
1255		example with the "sspi" command.
1256
1257		CONFIG_CMD_E1000
1258		Management command for E1000 devices.  When used on devices
1259		with SPI support you can reprogram the EEPROM from U-Boot.
1260
1261		CONFIG_EEPRO100
1262		Support for Intel 82557/82559/82559ER chips.
1263		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1264		write routine for first time initialisation.
1265
1266		CONFIG_TULIP
1267		Support for Digital 2114x chips.
1268		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1269		modem chip initialisation (KS8761/QS6611).
1270
1271		CONFIG_NATSEMI
1272		Support for National dp83815 chips.
1273
1274		CONFIG_NS8382X
1275		Support for National dp8382[01] gigabit chips.
1276
1277- NETWORK Support (other):
1278
1279		CONFIG_DRIVER_AT91EMAC
1280		Support for AT91RM9200 EMAC.
1281
1282			CONFIG_RMII
1283			Define this to use reduced MII inteface
1284
1285			CONFIG_DRIVER_AT91EMAC_QUIET
1286			If this defined, the driver is quiet.
1287			The driver doen't show link status messages.
1288
1289		CONFIG_CALXEDA_XGMAC
1290		Support for the Calxeda XGMAC device
1291
1292		CONFIG_LAN91C96
1293		Support for SMSC's LAN91C96 chips.
1294
1295			CONFIG_LAN91C96_USE_32_BIT
1296			Define this to enable 32 bit addressing
1297
1298		CONFIG_SMC91111
1299		Support for SMSC's LAN91C111 chip
1300
1301			CONFIG_SMC91111_BASE
1302			Define this to hold the physical address
1303			of the device (I/O space)
1304
1305			CONFIG_SMC_USE_32_BIT
1306			Define this if data bus is 32 bits
1307
1308			CONFIG_SMC_USE_IOFUNCS
1309			Define this to use i/o functions instead of macros
1310			(some hardware wont work with macros)
1311
1312		CONFIG_DRIVER_TI_EMAC
1313		Support for davinci emac
1314
1315			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1316			Define this if you have more then 3 PHYs.
1317
1318		CONFIG_FTGMAC100
1319		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1320
1321			CONFIG_FTGMAC100_EGIGA
1322			Define this to use GE link update with gigabit PHY.
1323			Define this if FTGMAC100 is connected to gigabit PHY.
1324			If your system has 10/100 PHY only, it might not occur
1325			wrong behavior. Because PHY usually return timeout or
1326			useless data when polling gigabit status and gigabit
1327			control registers. This behavior won't affect the
1328			correctnessof 10/100 link speed update.
1329
1330		CONFIG_SMC911X
1331		Support for SMSC's LAN911x and LAN921x chips
1332
1333			CONFIG_SMC911X_BASE
1334			Define this to hold the physical address
1335			of the device (I/O space)
1336
1337			CONFIG_SMC911X_32_BIT
1338			Define this if data bus is 32 bits
1339
1340			CONFIG_SMC911X_16_BIT
1341			Define this if data bus is 16 bits. If your processor
1342			automatically converts one 32 bit word to two 16 bit
1343			words you may also try CONFIG_SMC911X_32_BIT.
1344
1345		CONFIG_SH_ETHER
1346		Support for Renesas on-chip Ethernet controller
1347
1348			CONFIG_SH_ETHER_USE_PORT
1349			Define the number of ports to be used
1350
1351			CONFIG_SH_ETHER_PHY_ADDR
1352			Define the ETH PHY's address
1353
1354			CONFIG_SH_ETHER_CACHE_WRITEBACK
1355			If this option is set, the driver enables cache flush.
1356
1357- PWM Support:
1358		CONFIG_PWM_IMX
1359		Support for PWM module on the imx6.
1360
1361- TPM Support:
1362		CONFIG_TPM
1363		Support TPM devices.
1364
1365		CONFIG_TPM_TIS_INFINEON
1366		Support for Infineon i2c bus TPM devices. Only one device
1367		per system is supported at this time.
1368
1369			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1370			Define the burst count bytes upper limit
1371
1372		CONFIG_TPM_ST33ZP24
1373		Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1374
1375			CONFIG_TPM_ST33ZP24_I2C
1376			Support for STMicroelectronics ST33ZP24 I2C devices.
1377			Requires TPM_ST33ZP24 and I2C.
1378
1379			CONFIG_TPM_ST33ZP24_SPI
1380			Support for STMicroelectronics ST33ZP24 SPI devices.
1381			Requires TPM_ST33ZP24 and SPI.
1382
1383		CONFIG_TPM_ATMEL_TWI
1384		Support for Atmel TWI TPM device. Requires I2C support.
1385
1386		CONFIG_TPM_TIS_LPC
1387		Support for generic parallel port TPM devices. Only one device
1388		per system is supported at this time.
1389
1390			CONFIG_TPM_TIS_BASE_ADDRESS
1391			Base address where the generic TPM device is mapped
1392			to. Contemporary x86 systems usually map it at
1393			0xfed40000.
1394
1395		CONFIG_CMD_TPM
1396		Add tpm monitor functions.
1397		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1398		provides monitor access to authorized functions.
1399
1400		CONFIG_TPM
1401		Define this to enable the TPM support library which provides
1402		functional interfaces to some TPM commands.
1403		Requires support for a TPM device.
1404
1405		CONFIG_TPM_AUTH_SESSIONS
1406		Define this to enable authorized functions in the TPM library.
1407		Requires CONFIG_TPM and CONFIG_SHA1.
1408
1409- USB Support:
1410		At the moment only the UHCI host controller is
1411		supported (PIP405, MIP405, MPC5200); define
1412		CONFIG_USB_UHCI to enable it.
1413		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1414		and define CONFIG_USB_STORAGE to enable the USB
1415		storage devices.
1416		Note:
1417		Supported are USB Keyboards and USB Floppy drives
1418		(TEAC FD-05PUB).
1419		MPC5200 USB requires additional defines:
1420			CONFIG_USB_CLOCK
1421				for 528 MHz Clock: 0x0001bbbb
1422			CONFIG_PSC3_USB
1423				for USB on PSC3
1424			CONFIG_USB_CONFIG
1425				for differential drivers: 0x00001000
1426				for single ended drivers: 0x00005000
1427				for differential drivers on PSC3: 0x00000100
1428				for single ended drivers on PSC3: 0x00004100
1429			CONFIG_SYS_USB_EVENT_POLL
1430				May be defined to allow interrupt polling
1431				instead of using asynchronous interrupts
1432
1433		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1434		txfilltuning field in the EHCI controller on reset.
1435
1436		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1437		HW module registers.
1438
1439- USB Device:
1440		Define the below if you wish to use the USB console.
1441		Once firmware is rebuilt from a serial console issue the
1442		command "setenv stdin usbtty; setenv stdout usbtty" and
1443		attach your USB cable. The Unix command "dmesg" should print
1444		it has found a new device. The environment variable usbtty
1445		can be set to gserial or cdc_acm to enable your device to
1446		appear to a USB host as a Linux gserial device or a
1447		Common Device Class Abstract Control Model serial device.
1448		If you select usbtty = gserial you should be able to enumerate
1449		a Linux host by
1450		# modprobe usbserial vendor=0xVendorID product=0xProductID
1451		else if using cdc_acm, simply setting the environment
1452		variable usbtty to be cdc_acm should suffice. The following
1453		might be defined in YourBoardName.h
1454
1455			CONFIG_USB_DEVICE
1456			Define this to build a UDC device
1457
1458			CONFIG_USB_TTY
1459			Define this to have a tty type of device available to
1460			talk to the UDC device
1461
1462			CONFIG_USBD_HS
1463			Define this to enable the high speed support for usb
1464			device and usbtty. If this feature is enabled, a routine
1465			int is_usbd_high_speed(void)
1466			also needs to be defined by the driver to dynamically poll
1467			whether the enumeration has succeded at high speed or full
1468			speed.
1469
1470			CONFIG_SYS_CONSOLE_IS_IN_ENV
1471			Define this if you want stdin, stdout &/or stderr to
1472			be set to usbtty.
1473
1474			mpc8xx:
1475				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1476				Derive USB clock from external clock "blah"
1477				- CONFIG_SYS_USB_EXTC_CLK 0x02
1478
1479		If you have a USB-IF assigned VendorID then you may wish to
1480		define your own vendor specific values either in BoardName.h
1481		or directly in usbd_vendor_info.h. If you don't define
1482		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1483		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1484		should pretend to be a Linux device to it's target host.
1485
1486			CONFIG_USBD_MANUFACTURER
1487			Define this string as the name of your company for
1488			- CONFIG_USBD_MANUFACTURER "my company"
1489
1490			CONFIG_USBD_PRODUCT_NAME
1491			Define this string as the name of your product
1492			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1493
1494			CONFIG_USBD_VENDORID
1495			Define this as your assigned Vendor ID from the USB
1496			Implementors Forum. This *must* be a genuine Vendor ID
1497			to avoid polluting the USB namespace.
1498			- CONFIG_USBD_VENDORID 0xFFFF
1499
1500			CONFIG_USBD_PRODUCTID
1501			Define this as the unique Product ID
1502			for your device
1503			- CONFIG_USBD_PRODUCTID 0xFFFF
1504
1505- ULPI Layer Support:
1506		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1507		the generic ULPI layer. The generic layer accesses the ULPI PHY
1508		via the platform viewport, so you need both the genric layer and
1509		the viewport enabled. Currently only Chipidea/ARC based
1510		viewport is supported.
1511		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1512		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1513		If your ULPI phy needs a different reference clock than the
1514		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1515		the appropriate value in Hz.
1516
1517- MMC Support:
1518		The MMC controller on the Intel PXA is supported. To
1519		enable this define CONFIG_MMC. The MMC can be
1520		accessed from the boot prompt by mapping the device
1521		to physical memory similar to flash. Command line is
1522		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1523		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1524
1525		CONFIG_SH_MMCIF
1526		Support for Renesas on-chip MMCIF controller
1527
1528			CONFIG_SH_MMCIF_ADDR
1529			Define the base address of MMCIF registers
1530
1531			CONFIG_SH_MMCIF_CLK
1532			Define the clock frequency for MMCIF
1533
1534		CONFIG_GENERIC_MMC
1535		Enable the generic MMC driver
1536
1537		CONFIG_SUPPORT_EMMC_BOOT
1538		Enable some additional features of the eMMC boot partitions.
1539
1540		CONFIG_SUPPORT_EMMC_RPMB
1541		Enable the commands for reading, writing and programming the
1542		key for the Replay Protection Memory Block partition in eMMC.
1543
1544- USB Device Firmware Update (DFU) class support:
1545		CONFIG_USB_FUNCTION_DFU
1546		This enables the USB portion of the DFU USB class
1547
1548		CONFIG_CMD_DFU
1549		This enables the command "dfu" which is used to have
1550		U-Boot create a DFU class device via USB.  This command
1551		requires that the "dfu_alt_info" environment variable be
1552		set and define the alt settings to expose to the host.
1553
1554		CONFIG_DFU_MMC
1555		This enables support for exposing (e)MMC devices via DFU.
1556
1557		CONFIG_DFU_NAND
1558		This enables support for exposing NAND devices via DFU.
1559
1560		CONFIG_DFU_RAM
1561		This enables support for exposing RAM via DFU.
1562		Note: DFU spec refer to non-volatile memory usage, but
1563		allow usages beyond the scope of spec - here RAM usage,
1564		one that would help mostly the developer.
1565
1566		CONFIG_SYS_DFU_DATA_BUF_SIZE
1567		Dfu transfer uses a buffer before writing data to the
1568		raw storage device. Make the size (in bytes) of this buffer
1569		configurable. The size of this buffer is also configurable
1570		through the "dfu_bufsiz" environment variable.
1571
1572		CONFIG_SYS_DFU_MAX_FILE_SIZE
1573		When updating files rather than the raw storage device,
1574		we use a static buffer to copy the file into and then write
1575		the buffer once we've been given the whole file.  Define
1576		this to the maximum filesize (in bytes) for the buffer.
1577		Default is 4 MiB if undefined.
1578
1579		DFU_DEFAULT_POLL_TIMEOUT
1580		Poll timeout [ms], is the timeout a device can send to the
1581		host. The host must wait for this timeout before sending
1582		a subsequent DFU_GET_STATUS request to the device.
1583
1584		DFU_MANIFEST_POLL_TIMEOUT
1585		Poll timeout [ms], which the device sends to the host when
1586		entering dfuMANIFEST state. Host waits this timeout, before
1587		sending again an USB request to the device.
1588
1589- USB Device Android Fastboot support:
1590		CONFIG_USB_FUNCTION_FASTBOOT
1591		This enables the USB part of the fastboot gadget
1592
1593		CONFIG_CMD_FASTBOOT
1594		This enables the command "fastboot" which enables the Android
1595		fastboot mode for the platform's USB device. Fastboot is a USB
1596		protocol for downloading images, flashing and device control
1597		used on Android devices.
1598		See doc/README.android-fastboot for more information.
1599
1600		CONFIG_ANDROID_BOOT_IMAGE
1601		This enables support for booting images which use the Android
1602		image format header.
1603
1604		CONFIG_FASTBOOT_BUF_ADDR
1605		The fastboot protocol requires a large memory buffer for
1606		downloads. Define this to the starting RAM address to use for
1607		downloaded images.
1608
1609		CONFIG_FASTBOOT_BUF_SIZE
1610		The fastboot protocol requires a large memory buffer for
1611		downloads. This buffer should be as large as possible for a
1612		platform. Define this to the size available RAM for fastboot.
1613
1614		CONFIG_FASTBOOT_FLASH
1615		The fastboot protocol includes a "flash" command for writing
1616		the downloaded image to a non-volatile storage device. Define
1617		this to enable the "fastboot flash" command.
1618
1619		CONFIG_FASTBOOT_FLASH_MMC_DEV
1620		The fastboot "flash" command requires additional information
1621		regarding the non-volatile storage device. Define this to
1622		the eMMC device that fastboot should use to store the image.
1623
1624		CONFIG_FASTBOOT_GPT_NAME
1625		The fastboot "flash" command supports writing the downloaded
1626		image to the Protective MBR and the Primary GUID Partition
1627		Table. (Additionally, this downloaded image is post-processed
1628		to generate and write the Backup GUID Partition Table.)
1629		This occurs when the specified "partition name" on the
1630		"fastboot flash" command line matches this value.
1631		The default is "gpt" if undefined.
1632
1633		CONFIG_FASTBOOT_MBR_NAME
1634		The fastboot "flash" command supports writing the downloaded
1635		image to DOS MBR.
1636		This occurs when the "partition name" specified on the
1637		"fastboot flash" command line matches this value.
1638		If not defined the default value "mbr" is used.
1639
1640- Journaling Flash filesystem support:
1641		CONFIG_JFFS2_NAND
1642		Define these for a default partition on a NAND device
1643
1644		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1645		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1646		Define these for a default partition on a NOR device
1647
1648- FAT(File Allocation Table) filesystem write function support:
1649		CONFIG_FAT_WRITE
1650
1651		Define this to enable support for saving memory data as a
1652		file in FAT formatted partition.
1653
1654		This will also enable the command "fatwrite" enabling the
1655		user to write files to FAT.
1656
1657CBFS (Coreboot Filesystem) support
1658		CONFIG_CMD_CBFS
1659
1660		Define this to enable support for reading from a Coreboot
1661		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1662		and cbfsload.
1663
1664- FAT(File Allocation Table) filesystem cluster size:
1665		CONFIG_FS_FAT_MAX_CLUSTSIZE
1666
1667		Define the max cluster size for fat operations else
1668		a default value of 65536 will be defined.
1669
1670- Keyboard Support:
1671		See Kconfig help for available keyboard drivers.
1672
1673		CONFIG_KEYBOARD
1674
1675		Define this to enable a custom keyboard support.
1676		This simply calls drv_keyboard_init() which must be
1677		defined in your board-specific files. This option is deprecated
1678		and is only used by novena. For new boards, use driver model
1679		instead.
1680
1681- Video support:
1682		CONFIG_VIDEO
1683
1684		Define this to enable video support (for output to
1685		video).
1686
1687		CONFIG_VIDEO_CT69000
1688
1689		Enable Chips & Technologies 69000 Video chip
1690
1691		CONFIG_VIDEO_SMI_LYNXEM
1692		Enable Silicon Motion SMI 712/710/810 Video chip. The
1693		video output is selected via environment 'videoout'
1694		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1695		assumed.
1696
1697		For the CT69000 and SMI_LYNXEM drivers, videomode is
1698		selected via environment 'videomode'. Two different ways
1699		are possible:
1700		- "videomode=num"   'num' is a standard LiLo mode numbers.
1701		Following standard modes are supported	(* is default):
1702
1703		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1704		-------------+---------------------------------------------
1705		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1706		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1707		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1708		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1709		-------------+---------------------------------------------
1710		(i.e. setenv videomode 317; saveenv; reset;)
1711
1712		- "videomode=bootargs" all the video parameters are parsed
1713		from the bootargs. (See drivers/video/videomodes.c)
1714
1715
1716		CONFIG_VIDEO_SED13806
1717		Enable Epson SED13806 driver. This driver supports 8bpp
1718		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1719		or CONFIG_VIDEO_SED13806_16BPP
1720
1721		CONFIG_FSL_DIU_FB
1722		Enable the Freescale DIU video driver.	Reference boards for
1723		SOCs that have a DIU should define this macro to enable DIU
1724		support, and should also define these other macros:
1725
1726			CONFIG_SYS_DIU_ADDR
1727			CONFIG_VIDEO
1728			CONFIG_CMD_BMP
1729			CONFIG_CFB_CONSOLE
1730			CONFIG_VIDEO_SW_CURSOR
1731			CONFIG_VGA_AS_SINGLE_DEVICE
1732			CONFIG_VIDEO_LOGO
1733			CONFIG_VIDEO_BMP_LOGO
1734
1735		The DIU driver will look for the 'video-mode' environment
1736		variable, and if defined, enable the DIU as a console during
1737		boot.  See the documentation file doc/README.video for a
1738		description of this variable.
1739
1740- LCD Support:	CONFIG_LCD
1741
1742		Define this to enable LCD support (for output to LCD
1743		display); also select one of the supported displays
1744		by defining one of these:
1745
1746		CONFIG_ATMEL_LCD:
1747
1748			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1749
1750		CONFIG_NEC_NL6448AC33:
1751
1752			NEC NL6448AC33-18. Active, color, single scan.
1753
1754		CONFIG_NEC_NL6448BC20
1755
1756			NEC NL6448BC20-08. 6.5", 640x480.
1757			Active, color, single scan.
1758
1759		CONFIG_NEC_NL6448BC33_54
1760
1761			NEC NL6448BC33-54. 10.4", 640x480.
1762			Active, color, single scan.
1763
1764		CONFIG_SHARP_16x9
1765
1766			Sharp 320x240. Active, color, single scan.
1767			It isn't 16x9, and I am not sure what it is.
1768
1769		CONFIG_SHARP_LQ64D341
1770
1771			Sharp LQ64D341 display, 640x480.
1772			Active, color, single scan.
1773
1774		CONFIG_HLD1045
1775
1776			HLD1045 display, 640x480.
1777			Active, color, single scan.
1778
1779		CONFIG_OPTREX_BW
1780
1781			Optrex	 CBL50840-2 NF-FW 99 22 M5
1782			or
1783			Hitachi	 LMG6912RPFC-00T
1784			or
1785			Hitachi	 SP14Q002
1786
1787			320x240. Black & white.
1788
1789		Normally display is black on white background; define
1790		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1791
1792		CONFIG_LCD_ALIGNMENT
1793
1794		Normally the LCD is page-aligned (typically 4KB). If this is
1795		defined then the LCD will be aligned to this value instead.
1796		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1797		here, since it is cheaper to change data cache settings on
1798		a per-section basis.
1799
1800		CONFIG_CONSOLE_SCROLL_LINES
1801
1802		When the console need to be scrolled, this is the number of
1803		lines to scroll by. It defaults to 1. Increasing this makes
1804		the console jump but can help speed up operation when scrolling
1805		is slow.
1806
1807		CONFIG_LCD_ROTATION
1808
1809		Sometimes, for example if the display is mounted in portrait
1810		mode or even if it's mounted landscape but rotated by 180degree,
1811		we need to rotate our content of the display relative to the
1812		framebuffer, so that user can read the messages which are
1813		printed out.
1814		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1815		initialized with a given rotation from "vl_rot" out of
1816		"vidinfo_t" which is provided by the board specific code.
1817		The value for vl_rot is coded as following (matching to
1818		fbcon=rotate:<n> linux-kernel commandline):
1819		0 = no rotation respectively 0 degree
1820		1 = 90 degree rotation
1821		2 = 180 degree rotation
1822		3 = 270 degree rotation
1823
1824		If CONFIG_LCD_ROTATION is not defined, the console will be
1825		initialized with 0degree rotation.
1826
1827		CONFIG_LCD_BMP_RLE8
1828
1829		Support drawing of RLE8-compressed bitmaps on the LCD.
1830
1831		CONFIG_I2C_EDID
1832
1833		Enables an 'i2c edid' command which can read EDID
1834		information over I2C from an attached LCD display.
1835
1836- Splash Screen Support: CONFIG_SPLASH_SCREEN
1837
1838		If this option is set, the environment is checked for
1839		a variable "splashimage". If found, the usual display
1840		of logo, copyright and system information on the LCD
1841		is suppressed and the BMP image at the address
1842		specified in "splashimage" is loaded instead. The
1843		console is redirected to the "nulldev", too. This
1844		allows for a "silent" boot where a splash screen is
1845		loaded very quickly after power-on.
1846
1847		CONFIG_SPLASHIMAGE_GUARD
1848
1849		If this option is set, then U-Boot will prevent the environment
1850		variable "splashimage" from being set to a problematic address
1851		(see doc/README.displaying-bmps).
1852		This option is useful for targets where, due to alignment
1853		restrictions, an improperly aligned BMP image will cause a data
1854		abort. If you think you will not have problems with unaligned
1855		accesses (for example because your toolchain prevents them)
1856		there is no need to set this option.
1857
1858		CONFIG_SPLASH_SCREEN_ALIGN
1859
1860		If this option is set the splash image can be freely positioned
1861		on the screen. Environment variable "splashpos" specifies the
1862		position as "x,y". If a positive number is given it is used as
1863		number of pixel from left/top. If a negative number is given it
1864		is used as number of pixel from right/bottom. You can also
1865		specify 'm' for centering the image.
1866
1867		Example:
1868		setenv splashpos m,m
1869			=> image at center of screen
1870
1871		setenv splashpos 30,20
1872			=> image at x = 30 and y = 20
1873
1874		setenv splashpos -10,m
1875			=> vertically centered image
1876			   at x = dspWidth - bmpWidth - 9
1877
1878- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1879
1880		If this option is set, additionally to standard BMP
1881		images, gzipped BMP images can be displayed via the
1882		splashscreen support or the bmp command.
1883
1884- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1885
1886		If this option is set, 8-bit RLE compressed BMP images
1887		can be displayed via the splashscreen support or the
1888		bmp command.
1889
1890- Do compressing for memory range:
1891		CONFIG_CMD_ZIP
1892
1893		If this option is set, it would use zlib deflate method
1894		to compress the specified memory at its best effort.
1895
1896- Compression support:
1897		CONFIG_GZIP
1898
1899		Enabled by default to support gzip compressed images.
1900
1901		CONFIG_BZIP2
1902
1903		If this option is set, support for bzip2 compressed
1904		images is included. If not, only uncompressed and gzip
1905		compressed images are supported.
1906
1907		NOTE: the bzip2 algorithm requires a lot of RAM, so
1908		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1909		be at least 4MB.
1910
1911		CONFIG_LZMA
1912
1913		If this option is set, support for lzma compressed
1914		images is included.
1915
1916		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1917		requires an amount of dynamic memory that is given by the
1918		formula:
1919
1920			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1921
1922		Where lc and lp stand for, respectively, Literal context bits
1923		and Literal pos bits.
1924
1925		This value is upper-bounded by 14MB in the worst case. Anyway,
1926		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1927		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1928		a very small buffer.
1929
1930		Use the lzmainfo tool to determinate the lc and lp values and
1931		then calculate the amount of needed dynamic memory (ensuring
1932		the appropriate CONFIG_SYS_MALLOC_LEN value).
1933
1934		CONFIG_LZO
1935
1936		If this option is set, support for LZO compressed images
1937		is included.
1938
1939- MII/PHY support:
1940		CONFIG_PHY_ADDR
1941
1942		The address of PHY on MII bus.
1943
1944		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1945
1946		The clock frequency of the MII bus
1947
1948		CONFIG_PHY_GIGE
1949
1950		If this option is set, support for speed/duplex
1951		detection of gigabit PHY is included.
1952
1953		CONFIG_PHY_RESET_DELAY
1954
1955		Some PHY like Intel LXT971A need extra delay after
1956		reset before any MII register access is possible.
1957		For such PHY, set this option to the usec delay
1958		required. (minimum 300usec for LXT971A)
1959
1960		CONFIG_PHY_CMD_DELAY (ppc4xx)
1961
1962		Some PHY like Intel LXT971A need extra delay after
1963		command issued before MII status register can be read
1964
1965- IP address:
1966		CONFIG_IPADDR
1967
1968		Define a default value for the IP address to use for
1969		the default Ethernet interface, in case this is not
1970		determined through e.g. bootp.
1971		(Environment variable "ipaddr")
1972
1973- Server IP address:
1974		CONFIG_SERVERIP
1975
1976		Defines a default value for the IP address of a TFTP
1977		server to contact when using the "tftboot" command.
1978		(Environment variable "serverip")
1979
1980		CONFIG_KEEP_SERVERADDR
1981
1982		Keeps the server's MAC address, in the env 'serveraddr'
1983		for passing to bootargs (like Linux's netconsole option)
1984
1985- Gateway IP address:
1986		CONFIG_GATEWAYIP
1987
1988		Defines a default value for the IP address of the
1989		default router where packets to other networks are
1990		sent to.
1991		(Environment variable "gatewayip")
1992
1993- Subnet mask:
1994		CONFIG_NETMASK
1995
1996		Defines a default value for the subnet mask (or
1997		routing prefix) which is used to determine if an IP
1998		address belongs to the local subnet or needs to be
1999		forwarded through a router.
2000		(Environment variable "netmask")
2001
2002- Multicast TFTP Mode:
2003		CONFIG_MCAST_TFTP
2004
2005		Defines whether you want to support multicast TFTP as per
2006		rfc-2090; for example to work with atftp.  Lets lots of targets
2007		tftp down the same boot image concurrently.  Note: the Ethernet
2008		driver in use must provide a function: mcast() to join/leave a
2009		multicast group.
2010
2011- BOOTP Recovery Mode:
2012		CONFIG_BOOTP_RANDOM_DELAY
2013
2014		If you have many targets in a network that try to
2015		boot using BOOTP, you may want to avoid that all
2016		systems send out BOOTP requests at precisely the same
2017		moment (which would happen for instance at recovery
2018		from a power failure, when all systems will try to
2019		boot, thus flooding the BOOTP server. Defining
2020		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2021		inserted before sending out BOOTP requests. The
2022		following delays are inserted then:
2023
2024		1st BOOTP request:	delay 0 ... 1 sec
2025		2nd BOOTP request:	delay 0 ... 2 sec
2026		3rd BOOTP request:	delay 0 ... 4 sec
2027		4th and following
2028		BOOTP requests:		delay 0 ... 8 sec
2029
2030		CONFIG_BOOTP_ID_CACHE_SIZE
2031
2032		BOOTP packets are uniquely identified using a 32-bit ID. The
2033		server will copy the ID from client requests to responses and
2034		U-Boot will use this to determine if it is the destination of
2035		an incoming response. Some servers will check that addresses
2036		aren't in use before handing them out (usually using an ARP
2037		ping) and therefore take up to a few hundred milliseconds to
2038		respond. Network congestion may also influence the time it
2039		takes for a response to make it back to the client. If that
2040		time is too long, U-Boot will retransmit requests. In order
2041		to allow earlier responses to still be accepted after these
2042		retransmissions, U-Boot's BOOTP client keeps a small cache of
2043		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2044		cache. The default is to keep IDs for up to four outstanding
2045		requests. Increasing this will allow U-Boot to accept offers
2046		from a BOOTP client in networks with unusually high latency.
2047
2048- DHCP Advanced Options:
2049		You can fine tune the DHCP functionality by defining
2050		CONFIG_BOOTP_* symbols:
2051
2052		CONFIG_BOOTP_SUBNETMASK
2053		CONFIG_BOOTP_GATEWAY
2054		CONFIG_BOOTP_HOSTNAME
2055		CONFIG_BOOTP_NISDOMAIN
2056		CONFIG_BOOTP_BOOTPATH
2057		CONFIG_BOOTP_BOOTFILESIZE
2058		CONFIG_BOOTP_DNS
2059		CONFIG_BOOTP_DNS2
2060		CONFIG_BOOTP_SEND_HOSTNAME
2061		CONFIG_BOOTP_NTPSERVER
2062		CONFIG_BOOTP_TIMEOFFSET
2063		CONFIG_BOOTP_VENDOREX
2064		CONFIG_BOOTP_MAY_FAIL
2065
2066		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2067		environment variable, not the BOOTP server.
2068
2069		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2070		after the configured retry count, the call will fail
2071		instead of starting over.  This can be used to fail over
2072		to Link-local IP address configuration if the DHCP server
2073		is not available.
2074
2075		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2076		serverip from a DHCP server, it is possible that more
2077		than one DNS serverip is offered to the client.
2078		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2079		serverip will be stored in the additional environment
2080		variable "dnsip2". The first DNS serverip is always
2081		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2082		is defined.
2083
2084		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2085		to do a dynamic update of a DNS server. To do this, they
2086		need the hostname of the DHCP requester.
2087		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2088		of the "hostname" environment variable is passed as
2089		option 12 to the DHCP server.
2090
2091		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2092
2093		A 32bit value in microseconds for a delay between
2094		receiving a "DHCP Offer" and sending the "DHCP Request".
2095		This fixes a problem with certain DHCP servers that don't
2096		respond 100% of the time to a "DHCP request". E.g. On an
2097		AT91RM9200 processor running at 180MHz, this delay needed
2098		to be *at least* 15,000 usec before a Windows Server 2003
2099		DHCP server would reply 100% of the time. I recommend at
2100		least 50,000 usec to be safe. The alternative is to hope
2101		that one of the retries will be successful but note that
2102		the DHCP timeout and retry process takes a longer than
2103		this delay.
2104
2105 - Link-local IP address negotiation:
2106		Negotiate with other link-local clients on the local network
2107		for an address that doesn't require explicit configuration.
2108		This is especially useful if a DHCP server cannot be guaranteed
2109		to exist in all environments that the device must operate.
2110
2111		See doc/README.link-local for more information.
2112
2113 - CDP Options:
2114		CONFIG_CDP_DEVICE_ID
2115
2116		The device id used in CDP trigger frames.
2117
2118		CONFIG_CDP_DEVICE_ID_PREFIX
2119
2120		A two character string which is prefixed to the MAC address
2121		of the device.
2122
2123		CONFIG_CDP_PORT_ID
2124
2125		A printf format string which contains the ascii name of
2126		the port. Normally is set to "eth%d" which sets
2127		eth0 for the first Ethernet, eth1 for the second etc.
2128
2129		CONFIG_CDP_CAPABILITIES
2130
2131		A 32bit integer which indicates the device capabilities;
2132		0x00000010 for a normal host which does not forwards.
2133
2134		CONFIG_CDP_VERSION
2135
2136		An ascii string containing the version of the software.
2137
2138		CONFIG_CDP_PLATFORM
2139
2140		An ascii string containing the name of the platform.
2141
2142		CONFIG_CDP_TRIGGER
2143
2144		A 32bit integer sent on the trigger.
2145
2146		CONFIG_CDP_POWER_CONSUMPTION
2147
2148		A 16bit integer containing the power consumption of the
2149		device in .1 of milliwatts.
2150
2151		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2152
2153		A byte containing the id of the VLAN.
2154
2155- Status LED:	CONFIG_STATUS_LED
2156
2157		Several configurations allow to display the current
2158		status using a LED. For instance, the LED will blink
2159		fast while running U-Boot code, stop blinking as
2160		soon as a reply to a BOOTP request was received, and
2161		start blinking slow once the Linux kernel is running
2162		(supported by a status LED driver in the Linux
2163		kernel). Defining CONFIG_STATUS_LED enables this
2164		feature in U-Boot.
2165
2166		Additional options:
2167
2168		CONFIG_GPIO_LED
2169		The status LED can be connected to a GPIO pin.
2170		In such cases, the gpio_led driver can be used as a
2171		status LED backend implementation. Define CONFIG_GPIO_LED
2172		to include the gpio_led driver in the U-Boot binary.
2173
2174		CONFIG_GPIO_LED_INVERTED_TABLE
2175		Some GPIO connected LEDs may have inverted polarity in which
2176		case the GPIO high value corresponds to LED off state and
2177		GPIO low value corresponds to LED on state.
2178		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2179		with a list of GPIO LEDs that have inverted polarity.
2180
2181- CAN Support:	CONFIG_CAN_DRIVER
2182
2183		Defining CONFIG_CAN_DRIVER enables CAN driver support
2184		on those systems that support this (optional)
2185		feature, like the TQM8xxL modules.
2186
2187- I2C Support:	CONFIG_SYS_I2C
2188
2189		This enable the NEW i2c subsystem, and will allow you to use
2190		i2c commands at the u-boot command line (as long as you set
2191		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2192		based realtime clock chips or other i2c devices. See
2193		common/cmd_i2c.c for a description of the command line
2194		interface.
2195
2196		ported i2c driver to the new framework:
2197		- drivers/i2c/soft_i2c.c:
2198		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2199		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2200		    for defining speed and slave address
2201		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2202		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2203		    for defining speed and slave address
2204		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2205		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2206		    for defining speed and slave address
2207		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2208		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2209		    for defining speed and slave address
2210
2211		- drivers/i2c/fsl_i2c.c:
2212		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2213		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2214		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2215		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2216		    bus.
2217		  - If your board supports a second fsl i2c bus, define
2218		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2219		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2220		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2221		    second bus.
2222
2223		- drivers/i2c/tegra_i2c.c:
2224		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2225		  - This driver adds 4 i2c buses with a fix speed from
2226		    100000 and the slave addr 0!
2227
2228		- drivers/i2c/ppc4xx_i2c.c
2229		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2230		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2231		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2232
2233		- drivers/i2c/i2c_mxc.c
2234		  - activate this driver with CONFIG_SYS_I2C_MXC
2235		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2236		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2237		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2238		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2239		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2240		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2241		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2242		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2243		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2244		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2245		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2246		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2247		If those defines are not set, default value is 100000
2248		for speed, and 0 for slave.
2249
2250		- drivers/i2c/rcar_i2c.c:
2251		  - activate this driver with CONFIG_SYS_I2C_RCAR
2252		  - This driver adds 4 i2c buses
2253
2254		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2255		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2256		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2257		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2258		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2259		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2260		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2261		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2262		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2263
2264		- drivers/i2c/sh_i2c.c:
2265		  - activate this driver with CONFIG_SYS_I2C_SH
2266		  - This driver adds from 2 to 5 i2c buses
2267
2268		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2269		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2270		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2271		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2272		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2273		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2274		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2275		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2276		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2277		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2278		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2279
2280		- drivers/i2c/omap24xx_i2c.c
2281		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2282		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2283		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2284		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2285		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2286		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2287		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2288		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2289		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2290		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2291		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2292
2293		- drivers/i2c/zynq_i2c.c
2294		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2295		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2296		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2297
2298		- drivers/i2c/s3c24x0_i2c.c:
2299		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2300		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2301		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2302		    with a fix speed from 100000 and the slave addr 0!
2303
2304		- drivers/i2c/ihs_i2c.c
2305		  - activate this driver with CONFIG_SYS_I2C_IHS
2306		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2307		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2308		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2309		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2310		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2311		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2312		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2313		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2314		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2315		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2316		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2317		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2318		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2319		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2320		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2321		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2322		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2323		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2324		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2325		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2326		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2327
2328		additional defines:
2329
2330		CONFIG_SYS_NUM_I2C_BUSES
2331		Hold the number of i2c buses you want to use.
2332
2333		CONFIG_SYS_I2C_DIRECT_BUS
2334		define this, if you don't use i2c muxes on your hardware.
2335		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2336		omit this define.
2337
2338		CONFIG_SYS_I2C_MAX_HOPS
2339		define how many muxes are maximal consecutively connected
2340		on one i2c bus. If you not use i2c muxes, omit this
2341		define.
2342
2343		CONFIG_SYS_I2C_BUSES
2344		hold a list of buses you want to use, only used if
2345		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2346		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2347		CONFIG_SYS_NUM_I2C_BUSES = 9:
2348
2349		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2350					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2351					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2352					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2353					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2354					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2355					{1, {I2C_NULL_HOP}}, \
2356					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2357					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2358					}
2359
2360		which defines
2361			bus 0 on adapter 0 without a mux
2362			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2363			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2364			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2365			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2366			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2367			bus 6 on adapter 1 without a mux
2368			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2369			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2370
2371		If you do not have i2c muxes on your board, omit this define.
2372
2373- Legacy I2C Support:	CONFIG_HARD_I2C
2374
2375		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2376		provides the following compelling advantages:
2377
2378		- more than one i2c adapter is usable
2379		- approved multibus support
2380		- better i2c mux support
2381
2382		** Please consider updating your I2C driver now. **
2383
2384		These enable legacy I2C serial bus commands. Defining
2385		CONFIG_HARD_I2C will include the appropriate I2C driver
2386		for the selected CPU.
2387
2388		This will allow you to use i2c commands at the u-boot
2389		command line (as long as you set CONFIG_CMD_I2C in
2390		CONFIG_COMMANDS) and communicate with i2c based realtime
2391		clock chips. See common/cmd_i2c.c for a description of the
2392		command line interface.
2393
2394		CONFIG_HARD_I2C selects a hardware I2C controller.
2395
2396		There are several other quantities that must also be
2397		defined when you define CONFIG_HARD_I2C.
2398
2399		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2400		to be the frequency (in Hz) at which you wish your i2c bus
2401		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2402		the CPU's i2c node address).
2403
2404		Now, the u-boot i2c code for the mpc8xx
2405		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2406		and so its address should therefore be cleared to 0 (See,
2407		eg, MPC823e User's Manual p.16-473). So, set
2408		CONFIG_SYS_I2C_SLAVE to 0.
2409
2410		CONFIG_SYS_I2C_INIT_MPC5XXX
2411
2412		When a board is reset during an i2c bus transfer
2413		chips might think that the current transfer is still
2414		in progress.  Reset the slave devices by sending start
2415		commands until the slave device responds.
2416
2417		That's all that's required for CONFIG_HARD_I2C.
2418
2419		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2420		then the following macros need to be defined (examples are
2421		from include/configs/lwmon.h):
2422
2423		I2C_INIT
2424
2425		(Optional). Any commands necessary to enable the I2C
2426		controller or configure ports.
2427
2428		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2429
2430		I2C_PORT
2431
2432		(Only for MPC8260 CPU). The I/O port to use (the code
2433		assumes both bits are on the same port). Valid values
2434		are 0..3 for ports A..D.
2435
2436		I2C_ACTIVE
2437
2438		The code necessary to make the I2C data line active
2439		(driven).  If the data line is open collector, this
2440		define can be null.
2441
2442		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2443
2444		I2C_TRISTATE
2445
2446		The code necessary to make the I2C data line tri-stated
2447		(inactive).  If the data line is open collector, this
2448		define can be null.
2449
2450		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2451
2452		I2C_READ
2453
2454		Code that returns true if the I2C data line is high,
2455		false if it is low.
2456
2457		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2458
2459		I2C_SDA(bit)
2460
2461		If <bit> is true, sets the I2C data line high. If it
2462		is false, it clears it (low).
2463
2464		eg: #define I2C_SDA(bit) \
2465			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2466			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2467
2468		I2C_SCL(bit)
2469
2470		If <bit> is true, sets the I2C clock line high. If it
2471		is false, it clears it (low).
2472
2473		eg: #define I2C_SCL(bit) \
2474			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2475			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2476
2477		I2C_DELAY
2478
2479		This delay is invoked four times per clock cycle so this
2480		controls the rate of data transfer.  The data rate thus
2481		is 1 / (I2C_DELAY * 4). Often defined to be something
2482		like:
2483
2484		#define I2C_DELAY  udelay(2)
2485
2486		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2487
2488		If your arch supports the generic GPIO framework (asm/gpio.h),
2489		then you may alternatively define the two GPIOs that are to be
2490		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2491		have GPIO-based defaults assigned to them as appropriate.
2492
2493		You should define these to the GPIO value as given directly to
2494		the generic GPIO functions.
2495
2496		CONFIG_SYS_I2C_INIT_BOARD
2497
2498		When a board is reset during an i2c bus transfer
2499		chips might think that the current transfer is still
2500		in progress. On some boards it is possible to access
2501		the i2c SCLK line directly, either by using the
2502		processor pin as a GPIO or by having a second pin
2503		connected to the bus. If this option is defined a
2504		custom i2c_init_board() routine in boards/xxx/board.c
2505		is run early in the boot sequence.
2506
2507		CONFIG_SYS_I2C_BOARD_LATE_INIT
2508
2509		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2510		defined a custom i2c_board_late_init() routine in
2511		boards/xxx/board.c is run AFTER the operations in i2c_init()
2512		is completed. This callpoint can be used to unreset i2c bus
2513		using CPU i2c controller register accesses for CPUs whose i2c
2514		controller provide such a method. It is called at the end of
2515		i2c_init() to allow i2c_init operations to setup the i2c bus
2516		controller on the CPU (e.g. setting bus speed & slave address).
2517
2518		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2519
2520		This option enables configuration of bi_iic_fast[] flags
2521		in u-boot bd_info structure based on u-boot environment
2522		variable "i2cfast". (see also i2cfast)
2523
2524		CONFIG_I2C_MULTI_BUS
2525
2526		This option allows the use of multiple I2C buses, each of which
2527		must have a controller.	 At any point in time, only one bus is
2528		active.	 To switch to a different bus, use the 'i2c dev' command.
2529		Note that bus numbering is zero-based.
2530
2531		CONFIG_SYS_I2C_NOPROBES
2532
2533		This option specifies a list of I2C devices that will be skipped
2534		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2535		is set, specify a list of bus-device pairs.  Otherwise, specify
2536		a 1D array of device addresses
2537
2538		e.g.
2539			#undef	CONFIG_I2C_MULTI_BUS
2540			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2541
2542		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2543
2544			#define CONFIG_I2C_MULTI_BUS
2545			#define CONFIG_SYS_I2C_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2546
2547		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2548
2549		CONFIG_SYS_SPD_BUS_NUM
2550
2551		If defined, then this indicates the I2C bus number for DDR SPD.
2552		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2553
2554		CONFIG_SYS_RTC_BUS_NUM
2555
2556		If defined, then this indicates the I2C bus number for the RTC.
2557		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2558
2559		CONFIG_SYS_DTT_BUS_NUM
2560
2561		If defined, then this indicates the I2C bus number for the DTT.
2562		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2563
2564		CONFIG_SYS_I2C_DTT_ADDR:
2565
2566		If defined, specifies the I2C address of the DTT device.
2567		If not defined, then U-Boot uses predefined value for
2568		specified DTT device.
2569
2570		CONFIG_SOFT_I2C_READ_REPEATED_START
2571
2572		defining this will force the i2c_read() function in
2573		the soft_i2c driver to perform an I2C repeated start
2574		between writing the address pointer and reading the
2575		data.  If this define is omitted the default behaviour
2576		of doing a stop-start sequence will be used.  Most I2C
2577		devices can use either method, but some require one or
2578		the other.
2579
2580- SPI Support:	CONFIG_SPI
2581
2582		Enables SPI driver (so far only tested with
2583		SPI EEPROM, also an instance works with Crystal A/D and
2584		D/As on the SACSng board)
2585
2586		CONFIG_SH_SPI
2587
2588		Enables the driver for SPI controller on SuperH. Currently
2589		only SH7757 is supported.
2590
2591		CONFIG_SOFT_SPI
2592
2593		Enables a software (bit-bang) SPI driver rather than
2594		using hardware support. This is a general purpose
2595		driver that only requires three general I/O port pins
2596		(two outputs, one input) to function. If this is
2597		defined, the board configuration must define several
2598		SPI configuration items (port pins to use, etc). For
2599		an example, see include/configs/sacsng.h.
2600
2601		CONFIG_HARD_SPI
2602
2603		Enables a hardware SPI driver for general-purpose reads
2604		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2605		must define a list of chip-select function pointers.
2606		Currently supported on some MPC8xxx processors.	 For an
2607		example, see include/configs/mpc8349emds.h.
2608
2609		CONFIG_MXC_SPI
2610
2611		Enables the driver for the SPI controllers on i.MX and MXC
2612		SoCs. Currently i.MX31/35/51 are supported.
2613
2614		CONFIG_SYS_SPI_MXC_WAIT
2615		Timeout for waiting until spi transfer completed.
2616		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2617
2618- FPGA Support: CONFIG_FPGA
2619
2620		Enables FPGA subsystem.
2621
2622		CONFIG_FPGA_<vendor>
2623
2624		Enables support for specific chip vendors.
2625		(ALTERA, XILINX)
2626
2627		CONFIG_FPGA_<family>
2628
2629		Enables support for FPGA family.
2630		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2631
2632		CONFIG_FPGA_COUNT
2633
2634		Specify the number of FPGA devices to support.
2635
2636		CONFIG_CMD_FPGA_LOADMK
2637
2638		Enable support for fpga loadmk command
2639
2640		CONFIG_CMD_FPGA_LOADP
2641
2642		Enable support for fpga loadp command - load partial bitstream
2643
2644		CONFIG_CMD_FPGA_LOADBP
2645
2646		Enable support for fpga loadbp command - load partial bitstream
2647		(Xilinx only)
2648
2649		CONFIG_SYS_FPGA_PROG_FEEDBACK
2650
2651		Enable printing of hash marks during FPGA configuration.
2652
2653		CONFIG_SYS_FPGA_CHECK_BUSY
2654
2655		Enable checks on FPGA configuration interface busy
2656		status by the configuration function. This option
2657		will require a board or device specific function to
2658		be written.
2659
2660		CONFIG_FPGA_DELAY
2661
2662		If defined, a function that provides delays in the FPGA
2663		configuration driver.
2664
2665		CONFIG_SYS_FPGA_CHECK_CTRLC
2666		Allow Control-C to interrupt FPGA configuration
2667
2668		CONFIG_SYS_FPGA_CHECK_ERROR
2669
2670		Check for configuration errors during FPGA bitfile
2671		loading. For example, abort during Virtex II
2672		configuration if the INIT_B line goes low (which
2673		indicated a CRC error).
2674
2675		CONFIG_SYS_FPGA_WAIT_INIT
2676
2677		Maximum time to wait for the INIT_B line to de-assert
2678		after PROB_B has been de-asserted during a Virtex II
2679		FPGA configuration sequence. The default time is 500
2680		ms.
2681
2682		CONFIG_SYS_FPGA_WAIT_BUSY
2683
2684		Maximum time to wait for BUSY to de-assert during
2685		Virtex II FPGA configuration. The default is 5 ms.
2686
2687		CONFIG_SYS_FPGA_WAIT_CONFIG
2688
2689		Time to wait after FPGA configuration. The default is
2690		200 ms.
2691
2692- Configuration Management:
2693		CONFIG_BUILD_TARGET
2694
2695		Some SoCs need special image types (e.g. U-Boot binary
2696		with a special header) as build targets. By defining
2697		CONFIG_BUILD_TARGET in the SoC / board header, this
2698		special image will be automatically built upon calling
2699		make / buildman.
2700
2701		CONFIG_IDENT_STRING
2702
2703		If defined, this string will be added to the U-Boot
2704		version information (U_BOOT_VERSION)
2705
2706- Vendor Parameter Protection:
2707
2708		U-Boot considers the values of the environment
2709		variables "serial#" (Board Serial Number) and
2710		"ethaddr" (Ethernet Address) to be parameters that
2711		are set once by the board vendor / manufacturer, and
2712		protects these variables from casual modification by
2713		the user. Once set, these variables are read-only,
2714		and write or delete attempts are rejected. You can
2715		change this behaviour:
2716
2717		If CONFIG_ENV_OVERWRITE is #defined in your config
2718		file, the write protection for vendor parameters is
2719		completely disabled. Anybody can change or delete
2720		these parameters.
2721
2722		Alternatively, if you define _both_ an ethaddr in the
2723		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2724		Ethernet address is installed in the environment,
2725		which can be changed exactly ONCE by the user. [The
2726		serial# is unaffected by this, i. e. it remains
2727		read-only.]
2728
2729		The same can be accomplished in a more flexible way
2730		for any variable by configuring the type of access
2731		to allow for those variables in the ".flags" variable
2732		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2733
2734- Protected RAM:
2735		CONFIG_PRAM
2736
2737		Define this variable to enable the reservation of
2738		"protected RAM", i. e. RAM which is not overwritten
2739		by U-Boot. Define CONFIG_PRAM to hold the number of
2740		kB you want to reserve for pRAM. You can overwrite
2741		this default value by defining an environment
2742		variable "pram" to the number of kB you want to
2743		reserve. Note that the board info structure will
2744		still show the full amount of RAM. If pRAM is
2745		reserved, a new environment variable "mem" will
2746		automatically be defined to hold the amount of
2747		remaining RAM in a form that can be passed as boot
2748		argument to Linux, for instance like that:
2749
2750			setenv bootargs ... mem=\${mem}
2751			saveenv
2752
2753		This way you can tell Linux not to use this memory,
2754		either, which results in a memory region that will
2755		not be affected by reboots.
2756
2757		*WARNING* If your board configuration uses automatic
2758		detection of the RAM size, you must make sure that
2759		this memory test is non-destructive. So far, the
2760		following board configurations are known to be
2761		"pRAM-clean":
2762
2763			IVMS8, IVML24, SPD8xx, TQM8xxL,
2764			HERMES, IP860, RPXlite, LWMON,
2765			FLAGADM, TQM8260
2766
2767- Access to physical memory region (> 4GB)
2768		Some basic support is provided for operations on memory not
2769		normally accessible to U-Boot - e.g. some architectures
2770		support access to more than 4GB of memory on 32-bit
2771		machines using physical address extension or similar.
2772		Define CONFIG_PHYSMEM to access this basic support, which
2773		currently only supports clearing the memory.
2774
2775- Error Recovery:
2776		CONFIG_PANIC_HANG
2777
2778		Define this variable to stop the system in case of a
2779		fatal error, so that you have to reset it manually.
2780		This is probably NOT a good idea for an embedded
2781		system where you want the system to reboot
2782		automatically as fast as possible, but it may be
2783		useful during development since you can try to debug
2784		the conditions that lead to the situation.
2785
2786		CONFIG_NET_RETRY_COUNT
2787
2788		This variable defines the number of retries for
2789		network operations like ARP, RARP, TFTP, or BOOTP
2790		before giving up the operation. If not defined, a
2791		default value of 5 is used.
2792
2793		CONFIG_ARP_TIMEOUT
2794
2795		Timeout waiting for an ARP reply in milliseconds.
2796
2797		CONFIG_NFS_TIMEOUT
2798
2799		Timeout in milliseconds used in NFS protocol.
2800		If you encounter "ERROR: Cannot umount" in nfs command,
2801		try longer timeout such as
2802		#define CONFIG_NFS_TIMEOUT 10000UL
2803
2804- Command Interpreter:
2805		CONFIG_AUTO_COMPLETE
2806
2807		Enable auto completion of commands using TAB.
2808
2809		CONFIG_SYS_PROMPT_HUSH_PS2
2810
2811		This defines the secondary prompt string, which is
2812		printed when the command interpreter needs more input
2813		to complete a command. Usually "> ".
2814
2815	Note:
2816
2817		In the current implementation, the local variables
2818		space and global environment variables space are
2819		separated. Local variables are those you define by
2820		simply typing `name=value'. To access a local
2821		variable later on, you have write `$name' or
2822		`${name}'; to execute the contents of a variable
2823		directly type `$name' at the command prompt.
2824
2825		Global environment variables are those you use
2826		setenv/printenv to work with. To run a command stored
2827		in such a variable, you need to use the run command,
2828		and you must not use the '$' sign to access them.
2829
2830		To store commands and special characters in a
2831		variable, please use double quotation marks
2832		surrounding the whole text of the variable, instead
2833		of the backslashes before semicolons and special
2834		symbols.
2835
2836- Command Line Editing and History:
2837		CONFIG_CMDLINE_EDITING
2838
2839		Enable editing and History functions for interactive
2840		command line input operations
2841
2842- Command Line PS1/PS2 support:
2843		CONFIG_CMDLINE_PS_SUPPORT
2844
2845		Enable support for changing the command prompt string
2846		at run-time. Only static string is supported so far.
2847		The string is obtained from environment variables PS1
2848		and PS2.
2849
2850- Default Environment:
2851		CONFIG_EXTRA_ENV_SETTINGS
2852
2853		Define this to contain any number of null terminated
2854		strings (variable = value pairs) that will be part of
2855		the default environment compiled into the boot image.
2856
2857		For example, place something like this in your
2858		board's config file:
2859
2860		#define CONFIG_EXTRA_ENV_SETTINGS \
2861			"myvar1=value1\0" \
2862			"myvar2=value2\0"
2863
2864		Warning: This method is based on knowledge about the
2865		internal format how the environment is stored by the
2866		U-Boot code. This is NOT an official, exported
2867		interface! Although it is unlikely that this format
2868		will change soon, there is no guarantee either.
2869		You better know what you are doing here.
2870
2871		Note: overly (ab)use of the default environment is
2872		discouraged. Make sure to check other ways to preset
2873		the environment like the "source" command or the
2874		boot command first.
2875
2876		CONFIG_ENV_VARS_UBOOT_CONFIG
2877
2878		Define this in order to add variables describing the
2879		U-Boot build configuration to the default environment.
2880		These will be named arch, cpu, board, vendor, and soc.
2881
2882		Enabling this option will cause the following to be defined:
2883
2884		- CONFIG_SYS_ARCH
2885		- CONFIG_SYS_CPU
2886		- CONFIG_SYS_BOARD
2887		- CONFIG_SYS_VENDOR
2888		- CONFIG_SYS_SOC
2889
2890		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2891
2892		Define this in order to add variables describing certain
2893		run-time determined information about the hardware to the
2894		environment.  These will be named board_name, board_rev.
2895
2896		CONFIG_DELAY_ENVIRONMENT
2897
2898		Normally the environment is loaded when the board is
2899		initialised so that it is available to U-Boot. This inhibits
2900		that so that the environment is not available until
2901		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2902		this is instead controlled by the value of
2903		/config/load-environment.
2904
2905- Parallel Flash support:
2906		CONFIG_SYS_NO_FLASH
2907
2908		Traditionally U-Boot was run on systems with parallel NOR
2909		flash. This option is used to disable support for parallel NOR
2910		flash. This option should be defined if the board does not have
2911		parallel flash.
2912
2913		If this option is not defined one of the generic flash drivers
2914		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
2915		selected or the board must provide an implementation of the
2916		flash API (see include/flash.h).
2917
2918- DataFlash Support:
2919		CONFIG_HAS_DATAFLASH
2920
2921		Defining this option enables DataFlash features and
2922		allows to read/write in Dataflash via the standard
2923		commands cp, md...
2924
2925- Serial Flash support
2926		CONFIG_CMD_SF
2927
2928		Defining this option enables SPI flash commands
2929		'sf probe/read/write/erase/update'.
2930
2931		Usage requires an initial 'probe' to define the serial
2932		flash parameters, followed by read/write/erase/update
2933		commands.
2934
2935		The following defaults may be provided by the platform
2936		to handle the common case when only a single serial
2937		flash is present on the system.
2938
2939		CONFIG_SF_DEFAULT_BUS		Bus identifier
2940		CONFIG_SF_DEFAULT_CS		Chip-select
2941		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2942		CONFIG_SF_DEFAULT_SPEED		in Hz
2943
2944		CONFIG_CMD_SF_TEST
2945
2946		Define this option to include a destructive SPI flash
2947		test ('sf test').
2948
2949		CONFIG_SF_DUAL_FLASH		Dual flash memories
2950
2951		Define this option to use dual flash support where two flash
2952		memories can be connected with a given cs line.
2953		Currently Xilinx Zynq qspi supports these type of connections.
2954
2955- SystemACE Support:
2956		CONFIG_SYSTEMACE
2957
2958		Adding this option adds support for Xilinx SystemACE
2959		chips attached via some sort of local bus. The address
2960		of the chip must also be defined in the
2961		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2962
2963		#define CONFIG_SYSTEMACE
2964		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2965
2966		When SystemACE support is added, the "ace" device type
2967		becomes available to the fat commands, i.e. fatls.
2968
2969- TFTP Fixed UDP Port:
2970		CONFIG_TFTP_PORT
2971
2972		If this is defined, the environment variable tftpsrcp
2973		is used to supply the TFTP UDP source port value.
2974		If tftpsrcp isn't defined, the normal pseudo-random port
2975		number generator is used.
2976
2977		Also, the environment variable tftpdstp is used to supply
2978		the TFTP UDP destination port value.  If tftpdstp isn't
2979		defined, the normal port 69 is used.
2980
2981		The purpose for tftpsrcp is to allow a TFTP server to
2982		blindly start the TFTP transfer using the pre-configured
2983		target IP address and UDP port. This has the effect of
2984		"punching through" the (Windows XP) firewall, allowing
2985		the remainder of the TFTP transfer to proceed normally.
2986		A better solution is to properly configure the firewall,
2987		but sometimes that is not allowed.
2988
2989- Hashing support:
2990		CONFIG_CMD_HASH
2991
2992		This enables a generic 'hash' command which can produce
2993		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2994
2995		CONFIG_HASH_VERIFY
2996
2997		Enable the hash verify command (hash -v). This adds to code
2998		size a little.
2999
3000		CONFIG_SHA1 - This option enables support of hashing using SHA1
3001		algorithm. The hash is calculated in software.
3002		CONFIG_SHA256 - This option enables support of hashing using
3003		SHA256 algorithm. The hash is calculated in software.
3004		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
3005		for SHA1/SHA256 hashing.
3006		This affects the 'hash' command and also the
3007		hash_lookup_algo() function.
3008		CONFIG_SHA_PROG_HW_ACCEL - This option enables
3009		hardware-acceleration for SHA1/SHA256 progressive hashing.
3010		Data can be streamed in a block at a time and the hashing
3011		is performed in hardware.
3012
3013		Note: There is also a sha1sum command, which should perhaps
3014		be deprecated in favour of 'hash sha1'.
3015
3016- Freescale i.MX specific commands:
3017		CONFIG_CMD_HDMIDETECT
3018		This enables 'hdmidet' command which returns true if an
3019		HDMI monitor is detected.  This command is i.MX 6 specific.
3020
3021		CONFIG_CMD_BMODE
3022		This enables the 'bmode' (bootmode) command for forcing
3023		a boot from specific media.
3024
3025		This is useful for forcing the ROM's usb downloader to
3026		activate upon a watchdog reset which is nice when iterating
3027		on U-Boot.  Using the reset button or running bmode normal
3028		will set it back to normal.  This command currently
3029		supports i.MX53 and i.MX6.
3030
3031- bootcount support:
3032		CONFIG_BOOTCOUNT_LIMIT
3033
3034		This enables the bootcounter support, see:
3035		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3036
3037		CONFIG_AT91SAM9XE
3038		enable special bootcounter support on at91sam9xe based boards.
3039		CONFIG_BLACKFIN
3040		enable special bootcounter support on blackfin based boards.
3041		CONFIG_SOC_DA8XX
3042		enable special bootcounter support on da850 based boards.
3043		CONFIG_BOOTCOUNT_RAM
3044		enable support for the bootcounter in RAM
3045		CONFIG_BOOTCOUNT_I2C
3046		enable support for the bootcounter on an i2c (like RTC) device.
3047			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3048			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3049						    the bootcounter.
3050			CONFIG_BOOTCOUNT_ALEN = address len
3051
3052- Show boot progress:
3053		CONFIG_SHOW_BOOT_PROGRESS
3054
3055		Defining this option allows to add some board-
3056		specific code (calling a user-provided function
3057		"show_boot_progress(int)") that enables you to show
3058		the system's boot progress on some display (for
3059		example, some LED's) on your board. At the moment,
3060		the following checkpoints are implemented:
3061
3062
3063Legacy uImage format:
3064
3065  Arg	Where			When
3066    1	common/cmd_bootm.c	before attempting to boot an image
3067   -1	common/cmd_bootm.c	Image header has bad	 magic number
3068    2	common/cmd_bootm.c	Image header has correct magic number
3069   -2	common/cmd_bootm.c	Image header has bad	 checksum
3070    3	common/cmd_bootm.c	Image header has correct checksum
3071   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3072    4	common/cmd_bootm.c	Image data   has correct checksum
3073   -4	common/cmd_bootm.c	Image is for unsupported architecture
3074    5	common/cmd_bootm.c	Architecture check OK
3075   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3076    6	common/cmd_bootm.c	Image Type check OK
3077   -6	common/cmd_bootm.c	gunzip uncompression error
3078   -7	common/cmd_bootm.c	Unimplemented compression type
3079    7	common/cmd_bootm.c	Uncompression OK
3080    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3081   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3082
3083    9	common/image.c		Start initial ramdisk verification
3084  -10	common/image.c		Ramdisk header has bad	   magic number
3085  -11	common/image.c		Ramdisk header has bad	   checksum
3086   10	common/image.c		Ramdisk header is OK
3087  -12	common/image.c		Ramdisk data   has bad	   checksum
3088   11	common/image.c		Ramdisk data   has correct checksum
3089   12	common/image.c		Ramdisk verification complete, start loading
3090  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3091   13	common/image.c		Start multifile image verification
3092   14	common/image.c		No initial ramdisk, no multifile, continue.
3093
3094   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3095
3096  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3097  -31	post/post.c		POST test failed, detected by post_output_backlog()
3098  -32	post/post.c		POST test failed, detected by post_run_single()
3099
3100   34	common/cmd_doc.c	before loading a Image from a DOC device
3101  -35	common/cmd_doc.c	Bad usage of "doc" command
3102   35	common/cmd_doc.c	correct usage of "doc" command
3103  -36	common/cmd_doc.c	No boot device
3104   36	common/cmd_doc.c	correct boot device
3105  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3106   37	common/cmd_doc.c	correct chip ID found, device available
3107  -38	common/cmd_doc.c	Read Error on boot device
3108   38	common/cmd_doc.c	reading Image header from DOC device OK
3109  -39	common/cmd_doc.c	Image header has bad magic number
3110   39	common/cmd_doc.c	Image header has correct magic number
3111  -40	common/cmd_doc.c	Error reading Image from DOC device
3112   40	common/cmd_doc.c	Image header has correct magic number
3113   41	common/cmd_ide.c	before loading a Image from a IDE device
3114  -42	common/cmd_ide.c	Bad usage of "ide" command
3115   42	common/cmd_ide.c	correct usage of "ide" command
3116  -43	common/cmd_ide.c	No boot device
3117   43	common/cmd_ide.c	boot device found
3118  -44	common/cmd_ide.c	Device not available
3119   44	common/cmd_ide.c	Device available
3120  -45	common/cmd_ide.c	wrong partition selected
3121   45	common/cmd_ide.c	partition selected
3122  -46	common/cmd_ide.c	Unknown partition table
3123   46	common/cmd_ide.c	valid partition table found
3124  -47	common/cmd_ide.c	Invalid partition type
3125   47	common/cmd_ide.c	correct partition type
3126  -48	common/cmd_ide.c	Error reading Image Header on boot device
3127   48	common/cmd_ide.c	reading Image Header from IDE device OK
3128  -49	common/cmd_ide.c	Image header has bad magic number
3129   49	common/cmd_ide.c	Image header has correct magic number
3130  -50	common/cmd_ide.c	Image header has bad	 checksum
3131   50	common/cmd_ide.c	Image header has correct checksum
3132  -51	common/cmd_ide.c	Error reading Image from IDE device
3133   51	common/cmd_ide.c	reading Image from IDE device OK
3134   52	common/cmd_nand.c	before loading a Image from a NAND device
3135  -53	common/cmd_nand.c	Bad usage of "nand" command
3136   53	common/cmd_nand.c	correct usage of "nand" command
3137  -54	common/cmd_nand.c	No boot device
3138   54	common/cmd_nand.c	boot device found
3139  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3140   55	common/cmd_nand.c	correct chip ID found, device available
3141  -56	common/cmd_nand.c	Error reading Image Header on boot device
3142   56	common/cmd_nand.c	reading Image Header from NAND device OK
3143  -57	common/cmd_nand.c	Image header has bad magic number
3144   57	common/cmd_nand.c	Image header has correct magic number
3145  -58	common/cmd_nand.c	Error reading Image from NAND device
3146   58	common/cmd_nand.c	reading Image from NAND device OK
3147
3148  -60	common/env_common.c	Environment has a bad CRC, using default
3149
3150   64	net/eth.c		starting with Ethernet configuration.
3151  -64	net/eth.c		no Ethernet found.
3152   65	net/eth.c		Ethernet found.
3153
3154  -80	common/cmd_net.c	usage wrong
3155   80	common/cmd_net.c	before calling net_loop()
3156  -81	common/cmd_net.c	some error in net_loop() occurred
3157   81	common/cmd_net.c	net_loop() back without error
3158  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3159   82	common/cmd_net.c	trying automatic boot
3160   83	common/cmd_net.c	running "source" command
3161  -83	common/cmd_net.c	some error in automatic boot or "source" command
3162   84	common/cmd_net.c	end without errors
3163
3164FIT uImage format:
3165
3166  Arg	Where			When
3167  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3168 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3169  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3170 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3171  102	common/cmd_bootm.c	Kernel unit name specified
3172 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3173  103	common/cmd_bootm.c	Found configuration node
3174  104	common/cmd_bootm.c	Got kernel subimage node offset
3175 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3176  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3177 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3178  106	common/cmd_bootm.c	Architecture check OK
3179 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3180  107	common/cmd_bootm.c	Kernel subimage type OK
3181 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3182  108	common/cmd_bootm.c	Got kernel subimage data/size
3183 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3184 -109	common/cmd_bootm.c	Can't get kernel subimage type
3185 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3186 -111	common/cmd_bootm.c	Can't get kernel subimage os
3187 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3188 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3189
3190  120	common/image.c		Start initial ramdisk verification
3191 -120	common/image.c		Ramdisk FIT image has incorrect format
3192  121	common/image.c		Ramdisk FIT image has correct format
3193  122	common/image.c		No ramdisk subimage unit name, using configuration
3194 -122	common/image.c		Can't get configuration for ramdisk subimage
3195  123	common/image.c		Ramdisk unit name specified
3196 -124	common/image.c		Can't get ramdisk subimage node offset
3197  125	common/image.c		Got ramdisk subimage node offset
3198 -125	common/image.c		Ramdisk subimage hash verification failed
3199  126	common/image.c		Ramdisk subimage hash verification OK
3200 -126	common/image.c		Ramdisk subimage for unsupported architecture
3201  127	common/image.c		Architecture check OK
3202 -127	common/image.c		Can't get ramdisk subimage data/size
3203  128	common/image.c		Got ramdisk subimage data/size
3204  129	common/image.c		Can't get ramdisk load address
3205 -129	common/image.c		Got ramdisk load address
3206
3207 -130	common/cmd_doc.c	Incorrect FIT image format
3208  131	common/cmd_doc.c	FIT image format OK
3209
3210 -140	common/cmd_ide.c	Incorrect FIT image format
3211  141	common/cmd_ide.c	FIT image format OK
3212
3213 -150	common/cmd_nand.c	Incorrect FIT image format
3214  151	common/cmd_nand.c	FIT image format OK
3215
3216- legacy image format:
3217		CONFIG_IMAGE_FORMAT_LEGACY
3218		enables the legacy image format support in U-Boot.
3219
3220		Default:
3221		enabled if CONFIG_FIT_SIGNATURE is not defined.
3222
3223		CONFIG_DISABLE_IMAGE_LEGACY
3224		disable the legacy image format
3225
3226		This define is introduced, as the legacy image format is
3227		enabled per default for backward compatibility.
3228
3229- FIT image support:
3230		CONFIG_FIT_DISABLE_SHA256
3231		Supporting SHA256 hashes has quite an impact on binary size.
3232		For constrained systems sha256 hash support can be disabled
3233		with this option.
3234
3235		TODO(sjg@chromium.org): Adjust this option to be positive,
3236		and move it to Kconfig
3237
3238- Standalone program support:
3239		CONFIG_STANDALONE_LOAD_ADDR
3240
3241		This option defines a board specific value for the
3242		address where standalone program gets loaded, thus
3243		overwriting the architecture dependent default
3244		settings.
3245
3246- Frame Buffer Address:
3247		CONFIG_FB_ADDR
3248
3249		Define CONFIG_FB_ADDR if you want to use specific
3250		address for frame buffer.  This is typically the case
3251		when using a graphics controller has separate video
3252		memory.  U-Boot will then place the frame buffer at
3253		the given address instead of dynamically reserving it
3254		in system RAM by calling lcd_setmem(), which grabs
3255		the memory for the frame buffer depending on the
3256		configured panel size.
3257
3258		Please see board_init_f function.
3259
3260- Automatic software updates via TFTP server
3261		CONFIG_UPDATE_TFTP
3262		CONFIG_UPDATE_TFTP_CNT_MAX
3263		CONFIG_UPDATE_TFTP_MSEC_MAX
3264
3265		These options enable and control the auto-update feature;
3266		for a more detailed description refer to doc/README.update.
3267
3268- MTD Support (mtdparts command, UBI support)
3269		CONFIG_MTD_DEVICE
3270
3271		Adds the MTD device infrastructure from the Linux kernel.
3272		Needed for mtdparts command support.
3273
3274		CONFIG_MTD_PARTITIONS
3275
3276		Adds the MTD partitioning infrastructure from the Linux
3277		kernel. Needed for UBI support.
3278
3279- UBI support
3280		CONFIG_CMD_UBI
3281
3282		Adds commands for interacting with MTD partitions formatted
3283		with the UBI flash translation layer
3284
3285		Requires also defining CONFIG_RBTREE
3286
3287		CONFIG_UBI_SILENCE_MSG
3288
3289		Make the verbose messages from UBI stop printing.  This leaves
3290		warnings and errors enabled.
3291
3292
3293		CONFIG_MTD_UBI_WL_THRESHOLD
3294		This parameter defines the maximum difference between the highest
3295		erase counter value and the lowest erase counter value of eraseblocks
3296		of UBI devices. When this threshold is exceeded, UBI starts performing
3297		wear leveling by means of moving data from eraseblock with low erase
3298		counter to eraseblocks with high erase counter.
3299
3300		The default value should be OK for SLC NAND flashes, NOR flashes and
3301		other flashes which have eraseblock life-cycle 100000 or more.
3302		However, in case of MLC NAND flashes which typically have eraseblock
3303		life-cycle less than 10000, the threshold should be lessened (e.g.,
3304		to 128 or 256, although it does not have to be power of 2).
3305
3306		default: 4096
3307
3308		CONFIG_MTD_UBI_BEB_LIMIT
3309		This option specifies the maximum bad physical eraseblocks UBI
3310		expects on the MTD device (per 1024 eraseblocks). If the
3311		underlying flash does not admit of bad eraseblocks (e.g. NOR
3312		flash), this value is ignored.
3313
3314		NAND datasheets often specify the minimum and maximum NVM
3315		(Number of Valid Blocks) for the flashes' endurance lifetime.
3316		The maximum expected bad eraseblocks per 1024 eraseblocks
3317		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3318		which gives 20 for most NANDs (MaxNVB is basically the total
3319		count of eraseblocks on the chip).
3320
3321		To put it differently, if this value is 20, UBI will try to
3322		reserve about 1.9% of physical eraseblocks for bad blocks
3323		handling. And that will be 1.9% of eraseblocks on the entire
3324		NAND chip, not just the MTD partition UBI attaches. This means
3325		that if you have, say, a NAND flash chip admits maximum 40 bad
3326		eraseblocks, and it is split on two MTD partitions of the same
3327		size, UBI will reserve 40 eraseblocks when attaching a
3328		partition.
3329
3330		default: 20
3331
3332		CONFIG_MTD_UBI_FASTMAP
3333		Fastmap is a mechanism which allows attaching an UBI device
3334		in nearly constant time. Instead of scanning the whole MTD device it
3335		only has to locate a checkpoint (called fastmap) on the device.
3336		The on-flash fastmap contains all information needed to attach
3337		the device. Using fastmap makes only sense on large devices where
3338		attaching by scanning takes long. UBI will not automatically install
3339		a fastmap on old images, but you can set the UBI parameter
3340		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3341		that fastmap-enabled images are still usable with UBI implementations
3342		without	fastmap support. On typical flash devices the whole fastmap
3343		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3344
3345		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3346		Set this parameter to enable fastmap automatically on images
3347		without a fastmap.
3348		default: 0
3349
3350		CONFIG_MTD_UBI_FM_DEBUG
3351		Enable UBI fastmap debug
3352		default: 0
3353
3354- UBIFS support
3355		CONFIG_CMD_UBIFS
3356
3357		Adds commands for interacting with UBI volumes formatted as
3358		UBIFS.  UBIFS is read-only in u-boot.
3359
3360		Requires UBI support as well as CONFIG_LZO
3361
3362		CONFIG_UBIFS_SILENCE_MSG
3363
3364		Make the verbose messages from UBIFS stop printing.  This leaves
3365		warnings and errors enabled.
3366
3367- SPL framework
3368		CONFIG_SPL
3369		Enable building of SPL globally.
3370
3371		CONFIG_SPL_LDSCRIPT
3372		LDSCRIPT for linking the SPL binary.
3373
3374		CONFIG_SPL_MAX_FOOTPRINT
3375		Maximum size in memory allocated to the SPL, BSS included.
3376		When defined, the linker checks that the actual memory
3377		used by SPL from _start to __bss_end does not exceed it.
3378		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3379		must not be both defined at the same time.
3380
3381		CONFIG_SPL_MAX_SIZE
3382		Maximum size of the SPL image (text, data, rodata, and
3383		linker lists sections), BSS excluded.
3384		When defined, the linker checks that the actual size does
3385		not exceed it.
3386
3387		CONFIG_SPL_TEXT_BASE
3388		TEXT_BASE for linking the SPL binary.
3389
3390		CONFIG_SPL_RELOC_TEXT_BASE
3391		Address to relocate to.  If unspecified, this is equal to
3392		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3393
3394		CONFIG_SPL_BSS_START_ADDR
3395		Link address for the BSS within the SPL binary.
3396
3397		CONFIG_SPL_BSS_MAX_SIZE
3398		Maximum size in memory allocated to the SPL BSS.
3399		When defined, the linker checks that the actual memory used
3400		by SPL from __bss_start to __bss_end does not exceed it.
3401		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3402		must not be both defined at the same time.
3403
3404		CONFIG_SPL_STACK
3405		Adress of the start of the stack SPL will use
3406
3407		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3408		When defined, SPL will panic() if the image it has
3409		loaded does not have a signature.
3410		Defining this is useful when code which loads images
3411		in SPL cannot guarantee that absolutely all read errors
3412		will be caught.
3413		An example is the LPC32XX MLC NAND driver, which will
3414		consider that a completely unreadable NAND block is bad,
3415		and thus should be skipped silently.
3416
3417		CONFIG_SPL_ABORT_ON_RAW_IMAGE
3418		When defined, SPL will proceed to another boot method
3419		if the image it has loaded does not have a signature.
3420
3421		CONFIG_SPL_RELOC_STACK
3422		Adress of the start of the stack SPL will use after
3423		relocation.  If unspecified, this is equal to
3424		CONFIG_SPL_STACK.
3425
3426		CONFIG_SYS_SPL_MALLOC_START
3427		Starting address of the malloc pool used in SPL.
3428		When this option is set the full malloc is used in SPL and
3429		it is set up by spl_init() and before that, the simple malloc()
3430		can be used if CONFIG_SYS_MALLOC_F is defined.
3431
3432		CONFIG_SYS_SPL_MALLOC_SIZE
3433		The size of the malloc pool used in SPL.
3434
3435		CONFIG_SPL_FRAMEWORK
3436		Enable the SPL framework under common/.  This framework
3437		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3438		NAND loading of the Linux Kernel.
3439
3440		CONFIG_SPL_OS_BOOT
3441		Enable booting directly to an OS from SPL.
3442		See also: doc/README.falcon
3443
3444		CONFIG_SPL_DISPLAY_PRINT
3445		For ARM, enable an optional function to print more information
3446		about the running system.
3447
3448		CONFIG_SPL_INIT_MINIMAL
3449		Arch init code should be built for a very small image
3450
3451		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3452		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3453		Address and partition on the MMC to load U-Boot from
3454		when the MMC is being used in raw mode.
3455
3456		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3457		Partition on the MMC to load U-Boot from when the MMC is being
3458		used in raw mode
3459
3460		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3461		Sector to load kernel uImage from when MMC is being
3462		used in raw mode (for Falcon mode)
3463
3464		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3465		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3466		Sector and number of sectors to load kernel argument
3467		parameters from when MMC is being used in raw mode
3468		(for falcon mode)
3469
3470		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3471		Partition on the MMC to load U-Boot from when the MMC is being
3472		used in fs mode
3473
3474		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3475		Filename to read to load U-Boot when reading from filesystem
3476
3477		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3478		Filename to read to load kernel uImage when reading
3479		from filesystem (for Falcon mode)
3480
3481		CONFIG_SPL_FS_LOAD_ARGS_NAME
3482		Filename to read to load kernel argument parameters
3483		when reading from filesystem (for Falcon mode)
3484
3485		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3486		Set this for NAND SPL on PPC mpc83xx targets, so that
3487		start.S waits for the rest of the SPL to load before
3488		continuing (the hardware starts execution after just
3489		loading the first page rather than the full 4K).
3490
3491		CONFIG_SPL_SKIP_RELOCATE
3492		Avoid SPL relocation
3493
3494		CONFIG_SPL_NAND_BASE
3495		Include nand_base.c in the SPL.  Requires
3496		CONFIG_SPL_NAND_DRIVERS.
3497
3498		CONFIG_SPL_NAND_DRIVERS
3499		SPL uses normal NAND drivers, not minimal drivers.
3500
3501		CONFIG_SPL_NAND_ECC
3502		Include standard software ECC in the SPL
3503
3504		CONFIG_SPL_NAND_SIMPLE
3505		Support for NAND boot using simple NAND drivers that
3506		expose the cmd_ctrl() interface.
3507
3508		CONFIG_SPL_UBI
3509		Support for a lightweight UBI (fastmap) scanner and
3510		loader
3511
3512		CONFIG_SPL_NAND_RAW_ONLY
3513		Support to boot only raw u-boot.bin images. Use this only
3514		if you need to save space.
3515
3516		CONFIG_SPL_COMMON_INIT_DDR
3517		Set for common ddr init with serial presence detect in
3518		SPL binary.
3519
3520		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3521		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3522		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3523		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3524		CONFIG_SYS_NAND_ECCBYTES
3525		Defines the size and behavior of the NAND that SPL uses
3526		to read U-Boot
3527
3528		CONFIG_SPL_NAND_BOOT
3529		Add support NAND boot
3530
3531		CONFIG_SYS_NAND_U_BOOT_OFFS
3532		Location in NAND to read U-Boot from
3533
3534		CONFIG_SYS_NAND_U_BOOT_DST
3535		Location in memory to load U-Boot to
3536
3537		CONFIG_SYS_NAND_U_BOOT_SIZE
3538		Size of image to load
3539
3540		CONFIG_SYS_NAND_U_BOOT_START
3541		Entry point in loaded image to jump to
3542
3543		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3544		Define this if you need to first read the OOB and then the
3545		data. This is used, for example, on davinci platforms.
3546
3547		CONFIG_SPL_OMAP3_ID_NAND
3548		Support for an OMAP3-specific set of functions to return the
3549		ID and MFR of the first attached NAND chip, if present.
3550
3551		CONFIG_SPL_RAM_DEVICE
3552		Support for running image already present in ram, in SPL binary
3553
3554		CONFIG_SPL_PAD_TO
3555		Image offset to which the SPL should be padded before appending
3556		the SPL payload. By default, this is defined as
3557		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3558		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3559		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3560
3561		CONFIG_SPL_TARGET
3562		Final target image containing SPL and payload.  Some SPLs
3563		use an arch-specific makefile fragment instead, for
3564		example if more than one image needs to be produced.
3565
3566		CONFIG_FIT_SPL_PRINT
3567		Printing information about a FIT image adds quite a bit of
3568		code to SPL. So this is normally disabled in SPL. Use this
3569		option to re-enable it. This will affect the output of the
3570		bootm command when booting a FIT image.
3571
3572- TPL framework
3573		CONFIG_TPL
3574		Enable building of TPL globally.
3575
3576		CONFIG_TPL_PAD_TO
3577		Image offset to which the TPL should be padded before appending
3578		the TPL payload. By default, this is defined as
3579		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3580		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3581		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3582
3583- Interrupt support (PPC):
3584
3585		There are common interrupt_init() and timer_interrupt()
3586		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3587		for CPU specific initialization. interrupt_init_cpu()
3588		should set decrementer_count to appropriate value. If
3589		CPU resets decrementer automatically after interrupt
3590		(ppc4xx) it should set decrementer_count to zero.
3591		timer_interrupt() calls timer_interrupt_cpu() for CPU
3592		specific handling. If board has watchdog / status_led
3593		/ other_activity_monitor it works automatically from
3594		general timer_interrupt().
3595
3596
3597Board initialization settings:
3598------------------------------
3599
3600During Initialization u-boot calls a number of board specific functions
3601to allow the preparation of board specific prerequisites, e.g. pin setup
3602before drivers are initialized. To enable these callbacks the
3603following configuration macros have to be defined. Currently this is
3604architecture specific, so please check arch/your_architecture/lib/board.c
3605typically in board_init_f() and board_init_r().
3606
3607- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3608- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3609- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3610- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3611
3612Configuration Settings:
3613-----------------------
3614
3615- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3616		Optionally it can be defined to support 64-bit memory commands.
3617
3618- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3619		undefine this when you're short of memory.
3620
3621- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3622		width of the commands listed in the 'help' command output.
3623
3624- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3625		prompt for user input.
3626
3627- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3628
3629- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3630
3631- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3632
3633- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3634		the application (usually a Linux kernel) when it is
3635		booted
3636
3637- CONFIG_SYS_BAUDRATE_TABLE:
3638		List of legal baudrate settings for this board.
3639
3640- CONFIG_SYS_CONSOLE_INFO_QUIET
3641		Suppress display of console information at boot.
3642
3643- CONFIG_SYS_CONSOLE_IS_IN_ENV
3644		If the board specific function
3645			extern int overwrite_console (void);
3646		returns 1, the stdin, stderr and stdout are switched to the
3647		serial port, else the settings in the environment are used.
3648
3649- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3650		Enable the call to overwrite_console().
3651
3652- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3653		Enable overwrite of previous console environment settings.
3654
3655- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3656		Begin and End addresses of the area used by the
3657		simple memory test.
3658
3659- CONFIG_SYS_ALT_MEMTEST:
3660		Enable an alternate, more extensive memory test.
3661
3662- CONFIG_SYS_MEMTEST_SCRATCH:
3663		Scratch address used by the alternate memory test
3664		You only need to set this if address zero isn't writeable
3665
3666- CONFIG_SYS_MEM_RESERVE_SECURE
3667		Only implemented for ARMv8 for now.
3668		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3669		is substracted from total RAM and won't be reported to OS.
3670		This memory can be used as secure memory. A variable
3671		gd->arch.secure_ram is used to track the location. In systems
3672		the RAM base is not zero, or RAM is divided into banks,
3673		this variable needs to be recalcuated to get the address.
3674
3675- CONFIG_SYS_MEM_TOP_HIDE:
3676		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3677		this specified memory area will get subtracted from the top
3678		(end) of RAM and won't get "touched" at all by U-Boot. By
3679		fixing up gd->ram_size the Linux kernel should gets passed
3680		the now "corrected" memory size and won't touch it either.
3681		This should work for arch/ppc and arch/powerpc. Only Linux
3682		board ports in arch/powerpc with bootwrapper support that
3683		recalculate the memory size from the SDRAM controller setup
3684		will have to get fixed in Linux additionally.
3685
3686		This option can be used as a workaround for the 440EPx/GRx
3687		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3688		be touched.
3689
3690		WARNING: Please make sure that this value is a multiple of
3691		the Linux page size (normally 4k). If this is not the case,
3692		then the end address of the Linux memory will be located at a
3693		non page size aligned address and this could cause major
3694		problems.
3695
3696- CONFIG_SYS_LOADS_BAUD_CHANGE:
3697		Enable temporary baudrate change while serial download
3698
3699- CONFIG_SYS_SDRAM_BASE:
3700		Physical start address of SDRAM. _Must_ be 0 here.
3701
3702- CONFIG_SYS_FLASH_BASE:
3703		Physical start address of Flash memory.
3704
3705- CONFIG_SYS_MONITOR_BASE:
3706		Physical start address of boot monitor code (set by
3707		make config files to be same as the text base address
3708		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3709		CONFIG_SYS_FLASH_BASE when booting from flash.
3710
3711- CONFIG_SYS_MONITOR_LEN:
3712		Size of memory reserved for monitor code, used to
3713		determine _at_compile_time_ (!) if the environment is
3714		embedded within the U-Boot image, or in a separate
3715		flash sector.
3716
3717- CONFIG_SYS_MALLOC_LEN:
3718		Size of DRAM reserved for malloc() use.
3719
3720- CONFIG_SYS_MALLOC_F_LEN
3721		Size of the malloc() pool for use before relocation. If
3722		this is defined, then a very simple malloc() implementation
3723		will become available before relocation. The address is just
3724		below the global data, and the stack is moved down to make
3725		space.
3726
3727		This feature allocates regions with increasing addresses
3728		within the region. calloc() is supported, but realloc()
3729		is not available. free() is supported but does nothing.
3730		The memory will be freed (or in fact just forgotten) when
3731		U-Boot relocates itself.
3732
3733- CONFIG_SYS_MALLOC_SIMPLE
3734		Provides a simple and small malloc() and calloc() for those
3735		boards which do not use the full malloc in SPL (which is
3736		enabled with CONFIG_SYS_SPL_MALLOC_START).
3737
3738- CONFIG_SYS_NONCACHED_MEMORY:
3739		Size of non-cached memory area. This area of memory will be
3740		typically located right below the malloc() area and mapped
3741		uncached in the MMU. This is useful for drivers that would
3742		otherwise require a lot of explicit cache maintenance. For
3743		some drivers it's also impossible to properly maintain the
3744		cache. For example if the regions that need to be flushed
3745		are not a multiple of the cache-line size, *and* padding
3746		cannot be allocated between the regions to align them (i.e.
3747		if the HW requires a contiguous array of regions, and the
3748		size of each region is not cache-aligned), then a flush of
3749		one region may result in overwriting data that hardware has
3750		written to another region in the same cache-line. This can
3751		happen for example in network drivers where descriptors for
3752		buffers are typically smaller than the CPU cache-line (e.g.
3753		16 bytes vs. 32 or 64 bytes).
3754
3755		Non-cached memory is only supported on 32-bit ARM at present.
3756
3757- CONFIG_SYS_BOOTM_LEN:
3758		Normally compressed uImages are limited to an
3759		uncompressed size of 8 MBytes. If this is not enough,
3760		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3761		to adjust this setting to your needs.
3762
3763- CONFIG_SYS_BOOTMAPSZ:
3764		Maximum size of memory mapped by the startup code of
3765		the Linux kernel; all data that must be processed by
3766		the Linux kernel (bd_info, boot arguments, FDT blob if
3767		used) must be put below this limit, unless "bootm_low"
3768		environment variable is defined and non-zero. In such case
3769		all data for the Linux kernel must be between "bootm_low"
3770		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3771		variable "bootm_mapsize" will override the value of
3772		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3773		then the value in "bootm_size" will be used instead.
3774
3775- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3776		Enable initrd_high functionality.  If defined then the
3777		initrd_high feature is enabled and the bootm ramdisk subcommand
3778		is enabled.
3779
3780- CONFIG_SYS_BOOT_GET_CMDLINE:
3781		Enables allocating and saving kernel cmdline in space between
3782		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3783
3784- CONFIG_SYS_BOOT_GET_KBD:
3785		Enables allocating and saving a kernel copy of the bd_info in
3786		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3787
3788- CONFIG_SYS_MAX_FLASH_BANKS:
3789		Max number of Flash memory banks
3790
3791- CONFIG_SYS_MAX_FLASH_SECT:
3792		Max number of sectors on a Flash chip
3793
3794- CONFIG_SYS_FLASH_ERASE_TOUT:
3795		Timeout for Flash erase operations (in ms)
3796
3797- CONFIG_SYS_FLASH_WRITE_TOUT:
3798		Timeout for Flash write operations (in ms)
3799
3800- CONFIG_SYS_FLASH_LOCK_TOUT
3801		Timeout for Flash set sector lock bit operation (in ms)
3802
3803- CONFIG_SYS_FLASH_UNLOCK_TOUT
3804		Timeout for Flash clear lock bits operation (in ms)
3805
3806- CONFIG_SYS_FLASH_PROTECTION
3807		If defined, hardware flash sectors protection is used
3808		instead of U-Boot software protection.
3809
3810- CONFIG_SYS_DIRECT_FLASH_TFTP:
3811
3812		Enable TFTP transfers directly to flash memory;
3813		without this option such a download has to be
3814		performed in two steps: (1) download to RAM, and (2)
3815		copy from RAM to flash.
3816
3817		The two-step approach is usually more reliable, since
3818		you can check if the download worked before you erase
3819		the flash, but in some situations (when system RAM is
3820		too limited to allow for a temporary copy of the
3821		downloaded image) this option may be very useful.
3822
3823- CONFIG_SYS_FLASH_CFI:
3824		Define if the flash driver uses extra elements in the
3825		common flash structure for storing flash geometry.
3826
3827- CONFIG_FLASH_CFI_DRIVER
3828		This option also enables the building of the cfi_flash driver
3829		in the drivers directory
3830
3831- CONFIG_FLASH_CFI_MTD
3832		This option enables the building of the cfi_mtd driver
3833		in the drivers directory. The driver exports CFI flash
3834		to the MTD layer.
3835
3836- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3837		Use buffered writes to flash.
3838
3839- CONFIG_FLASH_SPANSION_S29WS_N
3840		s29ws-n MirrorBit flash has non-standard addresses for buffered
3841		write commands.
3842
3843- CONFIG_SYS_FLASH_QUIET_TEST
3844		If this option is defined, the common CFI flash doesn't
3845		print it's warning upon not recognized FLASH banks. This
3846		is useful, if some of the configured banks are only
3847		optionally available.
3848
3849- CONFIG_FLASH_SHOW_PROGRESS
3850		If defined (must be an integer), print out countdown
3851		digits and dots.  Recommended value: 45 (9..1) for 80
3852		column displays, 15 (3..1) for 40 column displays.
3853
3854- CONFIG_FLASH_VERIFY
3855		If defined, the content of the flash (destination) is compared
3856		against the source after the write operation. An error message
3857		will be printed when the contents are not identical.
3858		Please note that this option is useless in nearly all cases,
3859		since such flash programming errors usually are detected earlier
3860		while unprotecting/erasing/programming. Please only enable
3861		this option if you really know what you are doing.
3862
3863- CONFIG_SYS_RX_ETH_BUFFER:
3864		Defines the number of Ethernet receive buffers. On some
3865		Ethernet controllers it is recommended to set this value
3866		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3867		buffers can be full shortly after enabling the interface
3868		on high Ethernet traffic.
3869		Defaults to 4 if not defined.
3870
3871- CONFIG_ENV_MAX_ENTRIES
3872
3873	Maximum number of entries in the hash table that is used
3874	internally to store the environment settings. The default
3875	setting is supposed to be generous and should work in most
3876	cases. This setting can be used to tune behaviour; see
3877	lib/hashtable.c for details.
3878
3879- CONFIG_ENV_FLAGS_LIST_DEFAULT
3880- CONFIG_ENV_FLAGS_LIST_STATIC
3881	Enable validation of the values given to environment variables when
3882	calling env set.  Variables can be restricted to only decimal,
3883	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3884	the variables can also be restricted to IP address or MAC address.
3885
3886	The format of the list is:
3887		type_attribute = [s|d|x|b|i|m]
3888		access_attribute = [a|r|o|c]
3889		attributes = type_attribute[access_attribute]
3890		entry = variable_name[:attributes]
3891		list = entry[,list]
3892
3893	The type attributes are:
3894		s - String (default)
3895		d - Decimal
3896		x - Hexadecimal
3897		b - Boolean ([1yYtT|0nNfF])
3898		i - IP address
3899		m - MAC address
3900
3901	The access attributes are:
3902		a - Any (default)
3903		r - Read-only
3904		o - Write-once
3905		c - Change-default
3906
3907	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3908		Define this to a list (string) to define the ".flags"
3909		environment variable in the default or embedded environment.
3910
3911	- CONFIG_ENV_FLAGS_LIST_STATIC
3912		Define this to a list (string) to define validation that
3913		should be done if an entry is not found in the ".flags"
3914		environment variable.  To override a setting in the static
3915		list, simply add an entry for the same variable name to the
3916		".flags" variable.
3917
3918	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3919	regular expression. This allows multiple variables to define the same
3920	flags without explicitly listing them for each variable.
3921
3922- CONFIG_ENV_ACCESS_IGNORE_FORCE
3923	If defined, don't allow the -f switch to env set override variable
3924	access flags.
3925
3926- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3927	This is set by OMAP boards for the max time that reset should
3928	be asserted. See doc/README.omap-reset-time for details on how
3929	the value can be calculated on a given board.
3930
3931- CONFIG_USE_STDINT
3932	If stdint.h is available with your toolchain you can define this
3933	option to enable it. You can provide option 'USE_STDINT=1' when
3934	building U-Boot to enable this.
3935
3936The following definitions that deal with the placement and management
3937of environment data (variable area); in general, we support the
3938following configurations:
3939
3940- CONFIG_BUILD_ENVCRC:
3941
3942	Builds up envcrc with the target environment so that external utils
3943	may easily extract it and embed it in final U-Boot images.
3944
3945- CONFIG_ENV_IS_IN_FLASH:
3946
3947	Define this if the environment is in flash memory.
3948
3949	a) The environment occupies one whole flash sector, which is
3950	   "embedded" in the text segment with the U-Boot code. This
3951	   happens usually with "bottom boot sector" or "top boot
3952	   sector" type flash chips, which have several smaller
3953	   sectors at the start or the end. For instance, such a
3954	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3955	   such a case you would place the environment in one of the
3956	   4 kB sectors - with U-Boot code before and after it. With
3957	   "top boot sector" type flash chips, you would put the
3958	   environment in one of the last sectors, leaving a gap
3959	   between U-Boot and the environment.
3960
3961	- CONFIG_ENV_OFFSET:
3962
3963	   Offset of environment data (variable area) to the
3964	   beginning of flash memory; for instance, with bottom boot
3965	   type flash chips the second sector can be used: the offset
3966	   for this sector is given here.
3967
3968	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3969
3970	- CONFIG_ENV_ADDR:
3971
3972	   This is just another way to specify the start address of
3973	   the flash sector containing the environment (instead of
3974	   CONFIG_ENV_OFFSET).
3975
3976	- CONFIG_ENV_SECT_SIZE:
3977
3978	   Size of the sector containing the environment.
3979
3980
3981	b) Sometimes flash chips have few, equal sized, BIG sectors.
3982	   In such a case you don't want to spend a whole sector for
3983	   the environment.
3984
3985	- CONFIG_ENV_SIZE:
3986
3987	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3988	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3989	   of this flash sector for the environment. This saves
3990	   memory for the RAM copy of the environment.
3991
3992	   It may also save flash memory if you decide to use this
3993	   when your environment is "embedded" within U-Boot code,
3994	   since then the remainder of the flash sector could be used
3995	   for U-Boot code. It should be pointed out that this is
3996	   STRONGLY DISCOURAGED from a robustness point of view:
3997	   updating the environment in flash makes it always
3998	   necessary to erase the WHOLE sector. If something goes
3999	   wrong before the contents has been restored from a copy in
4000	   RAM, your target system will be dead.
4001
4002	- CONFIG_ENV_ADDR_REDUND
4003	  CONFIG_ENV_SIZE_REDUND
4004
4005	   These settings describe a second storage area used to hold
4006	   a redundant copy of the environment data, so that there is
4007	   a valid backup copy in case there is a power failure during
4008	   a "saveenv" operation.
4009
4010BE CAREFUL! Any changes to the flash layout, and some changes to the
4011source code will make it necessary to adapt <board>/u-boot.lds*
4012accordingly!
4013
4014
4015- CONFIG_ENV_IS_IN_NVRAM:
4016
4017	Define this if you have some non-volatile memory device
4018	(NVRAM, battery buffered SRAM) which you want to use for the
4019	environment.
4020
4021	- CONFIG_ENV_ADDR:
4022	- CONFIG_ENV_SIZE:
4023
4024	  These two #defines are used to determine the memory area you
4025	  want to use for environment. It is assumed that this memory
4026	  can just be read and written to, without any special
4027	  provision.
4028
4029BE CAREFUL! The first access to the environment happens quite early
4030in U-Boot initialization (when we try to get the setting of for the
4031console baudrate). You *MUST* have mapped your NVRAM area then, or
4032U-Boot will hang.
4033
4034Please note that even with NVRAM we still use a copy of the
4035environment in RAM: we could work on NVRAM directly, but we want to
4036keep settings there always unmodified except somebody uses "saveenv"
4037to save the current settings.
4038
4039
4040- CONFIG_ENV_IS_IN_EEPROM:
4041
4042	Use this if you have an EEPROM or similar serial access
4043	device and a driver for it.
4044
4045	- CONFIG_ENV_OFFSET:
4046	- CONFIG_ENV_SIZE:
4047
4048	  These two #defines specify the offset and size of the
4049	  environment area within the total memory of your EEPROM.
4050
4051	- CONFIG_SYS_I2C_EEPROM_ADDR:
4052	  If defined, specified the chip address of the EEPROM device.
4053	  The default address is zero.
4054
4055	- CONFIG_SYS_I2C_EEPROM_BUS:
4056	  If defined, specified the i2c bus of the EEPROM device.
4057
4058	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4059	  If defined, the number of bits used to address bytes in a
4060	  single page in the EEPROM device.  A 64 byte page, for example
4061	  would require six bits.
4062
4063	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4064	  If defined, the number of milliseconds to delay between
4065	  page writes.	The default is zero milliseconds.
4066
4067	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4068	  The length in bytes of the EEPROM memory array address.  Note
4069	  that this is NOT the chip address length!
4070
4071	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4072	  EEPROM chips that implement "address overflow" are ones
4073	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4074	  address and the extra bits end up in the "chip address" bit
4075	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4076	  byte chips.
4077
4078	  Note that we consider the length of the address field to
4079	  still be one byte because the extra address bits are hidden
4080	  in the chip address.
4081
4082	- CONFIG_SYS_EEPROM_SIZE:
4083	  The size in bytes of the EEPROM device.
4084
4085	- CONFIG_ENV_EEPROM_IS_ON_I2C
4086	  define this, if you have I2C and SPI activated, and your
4087	  EEPROM, which holds the environment, is on the I2C bus.
4088
4089	- CONFIG_I2C_ENV_EEPROM_BUS
4090	  if you have an Environment on an EEPROM reached over
4091	  I2C muxes, you can define here, how to reach this
4092	  EEPROM. For example:
4093
4094	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4095
4096	  EEPROM which holds the environment, is reached over
4097	  a pca9547 i2c mux with address 0x70, channel 3.
4098
4099- CONFIG_ENV_IS_IN_DATAFLASH:
4100
4101	Define this if you have a DataFlash memory device which you
4102	want to use for the environment.
4103
4104	- CONFIG_ENV_OFFSET:
4105	- CONFIG_ENV_ADDR:
4106	- CONFIG_ENV_SIZE:
4107
4108	  These three #defines specify the offset and size of the
4109	  environment area within the total memory of your DataFlash placed
4110	  at the specified address.
4111
4112- CONFIG_ENV_IS_IN_SPI_FLASH:
4113
4114	Define this if you have a SPI Flash memory device which you
4115	want to use for the environment.
4116
4117	- CONFIG_ENV_OFFSET:
4118	- CONFIG_ENV_SIZE:
4119
4120	  These two #defines specify the offset and size of the
4121	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4122	  aligned to an erase sector boundary.
4123
4124	- CONFIG_ENV_SECT_SIZE:
4125
4126	  Define the SPI flash's sector size.
4127
4128	- CONFIG_ENV_OFFSET_REDUND (optional):
4129
4130	  This setting describes a second storage area of CONFIG_ENV_SIZE
4131	  size used to hold a redundant copy of the environment data, so
4132	  that there is a valid backup copy in case there is a power failure
4133	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
4134	  aligned to an erase sector boundary.
4135
4136	- CONFIG_ENV_SPI_BUS (optional):
4137	- CONFIG_ENV_SPI_CS (optional):
4138
4139	  Define the SPI bus and chip select. If not defined they will be 0.
4140
4141	- CONFIG_ENV_SPI_MAX_HZ (optional):
4142
4143	  Define the SPI max work clock. If not defined then use 1MHz.
4144
4145	- CONFIG_ENV_SPI_MODE (optional):
4146
4147	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4148
4149- CONFIG_ENV_IS_IN_REMOTE:
4150
4151	Define this if you have a remote memory space which you
4152	want to use for the local device's environment.
4153
4154	- CONFIG_ENV_ADDR:
4155	- CONFIG_ENV_SIZE:
4156
4157	  These two #defines specify the address and size of the
4158	  environment area within the remote memory space. The
4159	  local device can get the environment from remote memory
4160	  space by SRIO or PCIE links.
4161
4162BE CAREFUL! For some special cases, the local device can not use
4163"saveenv" command. For example, the local device will get the
4164environment stored in a remote NOR flash by SRIO or PCIE link,
4165but it can not erase, write this NOR flash by SRIO or PCIE interface.
4166
4167- CONFIG_ENV_IS_IN_NAND:
4168
4169	Define this if you have a NAND device which you want to use
4170	for the environment.
4171
4172	- CONFIG_ENV_OFFSET:
4173	- CONFIG_ENV_SIZE:
4174
4175	  These two #defines specify the offset and size of the environment
4176	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4177	  aligned to an erase block boundary.
4178
4179	- CONFIG_ENV_OFFSET_REDUND (optional):
4180
4181	  This setting describes a second storage area of CONFIG_ENV_SIZE
4182	  size used to hold a redundant copy of the environment data, so
4183	  that there is a valid backup copy in case there is a power failure
4184	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
4185	  aligned to an erase block boundary.
4186
4187	- CONFIG_ENV_RANGE (optional):
4188
4189	  Specifies the length of the region in which the environment
4190	  can be written.  This should be a multiple of the NAND device's
4191	  block size.  Specifying a range with more erase blocks than
4192	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4193	  the range to be avoided.
4194
4195	- CONFIG_ENV_OFFSET_OOB (optional):
4196
4197	  Enables support for dynamically retrieving the offset of the
4198	  environment from block zero's out-of-band data.  The
4199	  "nand env.oob" command can be used to record this offset.
4200	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4201	  using CONFIG_ENV_OFFSET_OOB.
4202
4203- CONFIG_NAND_ENV_DST
4204
4205	Defines address in RAM to which the nand_spl code should copy the
4206	environment. If redundant environment is used, it will be copied to
4207	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4208
4209- CONFIG_ENV_IS_IN_UBI:
4210
4211	Define this if you have an UBI volume that you want to use for the
4212	environment.  This has the benefit of wear-leveling the environment
4213	accesses, which is important on NAND.
4214
4215	- CONFIG_ENV_UBI_PART:
4216
4217	  Define this to a string that is the mtd partition containing the UBI.
4218
4219	- CONFIG_ENV_UBI_VOLUME:
4220
4221	  Define this to the name of the volume that you want to store the
4222	  environment in.
4223
4224	- CONFIG_ENV_UBI_VOLUME_REDUND:
4225
4226	  Define this to the name of another volume to store a second copy of
4227	  the environment in.  This will enable redundant environments in UBI.
4228	  It is assumed that both volumes are in the same MTD partition.
4229
4230	- CONFIG_UBI_SILENCE_MSG
4231	- CONFIG_UBIFS_SILENCE_MSG
4232
4233	  You will probably want to define these to avoid a really noisy system
4234	  when storing the env in UBI.
4235
4236- CONFIG_ENV_IS_IN_FAT:
4237       Define this if you want to use the FAT file system for the environment.
4238
4239       - FAT_ENV_INTERFACE:
4240
4241         Define this to a string that is the name of the block device.
4242
4243       - FAT_ENV_DEV_AND_PART:
4244
4245         Define this to a string to specify the partition of the device. It can
4246         be as following:
4247
4248           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4249               - "D:P": device D partition P. Error occurs if device D has no
4250                        partition table.
4251               - "D:0": device D.
4252               - "D" or "D:": device D partition 1 if device D has partition
4253                              table, or the whole device D if has no partition
4254                              table.
4255               - "D:auto": first partition in device D with bootable flag set.
4256                           If none, first valid partition in device D. If no
4257                           partition table then means device D.
4258
4259       - FAT_ENV_FILE:
4260
4261         It's a string of the FAT file name. This file use to store the
4262         environment.
4263
4264       - CONFIG_FAT_WRITE:
4265         This should be defined. Otherwise it cannot save the environment file.
4266
4267- CONFIG_ENV_IS_IN_MMC:
4268
4269	Define this if you have an MMC device which you want to use for the
4270	environment.
4271
4272	- CONFIG_SYS_MMC_ENV_DEV:
4273
4274	  Specifies which MMC device the environment is stored in.
4275
4276	- CONFIG_SYS_MMC_ENV_PART (optional):
4277
4278	  Specifies which MMC partition the environment is stored in. If not
4279	  set, defaults to partition 0, the user area. Common values might be
4280	  1 (first MMC boot partition), 2 (second MMC boot partition).
4281
4282	- CONFIG_ENV_OFFSET:
4283	- CONFIG_ENV_SIZE:
4284
4285	  These two #defines specify the offset and size of the environment
4286	  area within the specified MMC device.
4287
4288	  If offset is positive (the usual case), it is treated as relative to
4289	  the start of the MMC partition. If offset is negative, it is treated
4290	  as relative to the end of the MMC partition. This can be useful if
4291	  your board may be fitted with different MMC devices, which have
4292	  different sizes for the MMC partitions, and you always want the
4293	  environment placed at the very end of the partition, to leave the
4294	  maximum possible space before it, to store other data.
4295
4296	  These two values are in units of bytes, but must be aligned to an
4297	  MMC sector boundary.
4298
4299	- CONFIG_ENV_OFFSET_REDUND (optional):
4300
4301	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4302	  hold a redundant copy of the environment data. This provides a
4303	  valid backup copy in case the other copy is corrupted, e.g. due
4304	  to a power failure during a "saveenv" operation.
4305
4306	  This value may also be positive or negative; this is handled in the
4307	  same way as CONFIG_ENV_OFFSET.
4308
4309	  This value is also in units of bytes, but must also be aligned to
4310	  an MMC sector boundary.
4311
4312	- CONFIG_ENV_SIZE_REDUND (optional):
4313
4314	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4315	  set. If this value is set, it must be set to the same value as
4316	  CONFIG_ENV_SIZE.
4317
4318- CONFIG_SYS_SPI_INIT_OFFSET
4319
4320	Defines offset to the initial SPI buffer area in DPRAM. The
4321	area is used at an early stage (ROM part) if the environment
4322	is configured to reside in the SPI EEPROM: We need a 520 byte
4323	scratch DPRAM area. It is used between the two initialization
4324	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4325	to be a good choice since it makes it far enough from the
4326	start of the data area as well as from the stack pointer.
4327
4328Please note that the environment is read-only until the monitor
4329has been relocated to RAM and a RAM copy of the environment has been
4330created; also, when using EEPROM you will have to use getenv_f()
4331until then to read environment variables.
4332
4333The environment is protected by a CRC32 checksum. Before the monitor
4334is relocated into RAM, as a result of a bad CRC you will be working
4335with the compiled-in default environment - *silently*!!! [This is
4336necessary, because the first environment variable we need is the
4337"baudrate" setting for the console - if we have a bad CRC, we don't
4338have any device yet where we could complain.]
4339
4340Note: once the monitor has been relocated, then it will complain if
4341the default environment is used; a new CRC is computed as soon as you
4342use the "saveenv" command to store a valid environment.
4343
4344- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4345		Echo the inverted Ethernet link state to the fault LED.
4346
4347		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4348		      also needs to be defined.
4349
4350- CONFIG_SYS_FAULT_MII_ADDR:
4351		MII address of the PHY to check for the Ethernet link state.
4352
4353- CONFIG_NS16550_MIN_FUNCTIONS:
4354		Define this if you desire to only have use of the NS16550_init
4355		and NS16550_putc functions for the serial driver located at
4356		drivers/serial/ns16550.c.  This option is useful for saving
4357		space for already greatly restricted images, including but not
4358		limited to NAND_SPL configurations.
4359
4360- CONFIG_DISPLAY_BOARDINFO
4361		Display information about the board that U-Boot is running on
4362		when U-Boot starts up. The board function checkboard() is called
4363		to do this.
4364
4365- CONFIG_DISPLAY_BOARDINFO_LATE
4366		Similar to the previous option, but display this information
4367		later, once stdio is running and output goes to the LCD, if
4368		present.
4369
4370- CONFIG_BOARD_SIZE_LIMIT:
4371		Maximum size of the U-Boot image. When defined, the
4372		build system checks that the actual size does not
4373		exceed it.
4374
4375Low Level (hardware related) configuration options:
4376---------------------------------------------------
4377
4378- CONFIG_SYS_CACHELINE_SIZE:
4379		Cache Line Size of the CPU.
4380
4381- CONFIG_SYS_DEFAULT_IMMR:
4382		Default address of the IMMR after system reset.
4383
4384		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4385		and RPXsuper) to be able to adjust the position of
4386		the IMMR register after a reset.
4387
4388- CONFIG_SYS_CCSRBAR_DEFAULT:
4389		Default (power-on reset) physical address of CCSR on Freescale
4390		PowerPC SOCs.
4391
4392- CONFIG_SYS_CCSRBAR:
4393		Virtual address of CCSR.  On a 32-bit build, this is typically
4394		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4395
4396		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4397		for cross-platform code that uses that macro instead.
4398
4399- CONFIG_SYS_CCSRBAR_PHYS:
4400		Physical address of CCSR.  CCSR can be relocated to a new
4401		physical address, if desired.  In this case, this macro should
4402		be set to that address.	 Otherwise, it should be set to the
4403		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4404		is typically relocated on 36-bit builds.  It is recommended
4405		that this macro be defined via the _HIGH and _LOW macros:
4406
4407		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4408			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4409
4410- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4411		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4412		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4413		used in assembly code, so it must not contain typecasts or
4414		integer size suffixes (e.g. "ULL").
4415
4416- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4417		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4418		used in assembly code, so it must not contain typecasts or
4419		integer size suffixes (e.g. "ULL").
4420
4421- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4422		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4423		forced to a value that ensures that CCSR is not relocated.
4424
4425- Floppy Disk Support:
4426		CONFIG_SYS_FDC_DRIVE_NUMBER
4427
4428		the default drive number (default value 0)
4429
4430		CONFIG_SYS_ISA_IO_STRIDE
4431
4432		defines the spacing between FDC chipset registers
4433		(default value 1)
4434
4435		CONFIG_SYS_ISA_IO_OFFSET
4436
4437		defines the offset of register from address. It
4438		depends on which part of the data bus is connected to
4439		the FDC chipset. (default value 0)
4440
4441		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4442		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4443		default value.
4444
4445		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4446		fdc_hw_init() is called at the beginning of the FDC
4447		setup. fdc_hw_init() must be provided by the board
4448		source code. It is used to make hardware-dependent
4449		initializations.
4450
4451- CONFIG_IDE_AHB:
4452		Most IDE controllers were designed to be connected with PCI
4453		interface. Only few of them were designed for AHB interface.
4454		When software is doing ATA command and data transfer to
4455		IDE devices through IDE-AHB controller, some additional
4456		registers accessing to these kind of IDE-AHB controller
4457		is required.
4458
4459- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4460		DO NOT CHANGE unless you know exactly what you're
4461		doing! (11-4) [MPC8xx/82xx systems only]
4462
4463- CONFIG_SYS_INIT_RAM_ADDR:
4464
4465		Start address of memory area that can be used for
4466		initial data and stack; please note that this must be
4467		writable memory that is working WITHOUT special
4468		initialization, i. e. you CANNOT use normal RAM which
4469		will become available only after programming the
4470		memory controller and running certain initialization
4471		sequences.
4472
4473		U-Boot uses the following memory types:
4474		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4475		- MPC824X: data cache
4476		- PPC4xx:  data cache
4477
4478- CONFIG_SYS_GBL_DATA_OFFSET:
4479
4480		Offset of the initial data structure in the memory
4481		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4482		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4483		data is located at the end of the available space
4484		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4485		GENERATED_GBL_DATA_SIZE), and the initial stack is just
4486		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4487		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4488
4489	Note:
4490		On the MPC824X (or other systems that use the data
4491		cache for initial memory) the address chosen for
4492		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4493		point to an otherwise UNUSED address space between
4494		the top of RAM and the start of the PCI space.
4495
4496- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4497
4498- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4499
4500- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4501
4502- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4503
4504- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4505
4506- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4507
4508- CONFIG_SYS_OR_TIMING_SDRAM:
4509		SDRAM timing
4510
4511- CONFIG_SYS_MAMR_PTA:
4512		periodic timer for refresh
4513
4514- CONFIG_SYS_DER:	Debug Event Register (37-47)
4515
4516- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4517  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4518  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4519  CONFIG_SYS_BR1_PRELIM:
4520		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4521
4522- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4523  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4524  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4525		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4526
4527- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4528  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4529		Machine Mode Register and Memory Periodic Timer
4530		Prescaler definitions (SDRAM timing)
4531
4532- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4533		enable I2C microcode relocation patch (MPC8xx);
4534		define relocation offset in DPRAM [DSP2]
4535
4536- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4537		enable SMC microcode relocation patch (MPC8xx);
4538		define relocation offset in DPRAM [SMC1]
4539
4540- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4541		enable SPI microcode relocation patch (MPC8xx);
4542		define relocation offset in DPRAM [SCC4]
4543
4544- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4545		Offset of the bootmode word in DPRAM used by post
4546		(Power On Self Tests). This definition overrides
4547		#define'd default value in commproc.h resp.
4548		cpm_8260.h.
4549
4550- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4551  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4552  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4553  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4554  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4555  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4556  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4557  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4558		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4559
4560- CONFIG_PCI_DISABLE_PCIE:
4561		Disable PCI-Express on systems where it is supported but not
4562		required.
4563
4564- CONFIG_PCI_ENUM_ONLY
4565		Only scan through and get the devices on the buses.
4566		Don't do any setup work, presumably because someone or
4567		something has already done it, and we don't need to do it
4568		a second time.	Useful for platforms that are pre-booted
4569		by coreboot or similar.
4570
4571- CONFIG_PCI_INDIRECT_BRIDGE:
4572		Enable support for indirect PCI bridges.
4573
4574- CONFIG_SYS_SRIO:
4575		Chip has SRIO or not
4576
4577- CONFIG_SRIO1:
4578		Board has SRIO 1 port available
4579
4580- CONFIG_SRIO2:
4581		Board has SRIO 2 port available
4582
4583- CONFIG_SRIO_PCIE_BOOT_MASTER
4584		Board can support master function for Boot from SRIO and PCIE
4585
4586- CONFIG_SYS_SRIOn_MEM_VIRT:
4587		Virtual Address of SRIO port 'n' memory region
4588
4589- CONFIG_SYS_SRIOn_MEM_PHYS:
4590		Physical Address of SRIO port 'n' memory region
4591
4592- CONFIG_SYS_SRIOn_MEM_SIZE:
4593		Size of SRIO port 'n' memory region
4594
4595- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4596		Defined to tell the NAND controller that the NAND chip is using
4597		a 16 bit bus.
4598		Not all NAND drivers use this symbol.
4599		Example of drivers that use it:
4600		- drivers/mtd/nand/ndfc.c
4601		- drivers/mtd/nand/mxc_nand.c
4602
4603- CONFIG_SYS_NDFC_EBC0_CFG
4604		Sets the EBC0_CFG register for the NDFC. If not defined
4605		a default value will be used.
4606
4607- CONFIG_SPD_EEPROM
4608		Get DDR timing information from an I2C EEPROM. Common
4609		with pluggable memory modules such as SODIMMs
4610
4611  SPD_EEPROM_ADDRESS
4612		I2C address of the SPD EEPROM
4613
4614- CONFIG_SYS_SPD_BUS_NUM
4615		If SPD EEPROM is on an I2C bus other than the first
4616		one, specify here. Note that the value must resolve
4617		to something your driver can deal with.
4618
4619- CONFIG_SYS_DDR_RAW_TIMING
4620		Get DDR timing information from other than SPD. Common with
4621		soldered DDR chips onboard without SPD. DDR raw timing
4622		parameters are extracted from datasheet and hard-coded into
4623		header files or board specific files.
4624
4625- CONFIG_FSL_DDR_INTERACTIVE
4626		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4627
4628- CONFIG_FSL_DDR_SYNC_REFRESH
4629		Enable sync of refresh for multiple controllers.
4630
4631- CONFIG_FSL_DDR_BIST
4632		Enable built-in memory test for Freescale DDR controllers.
4633
4634- CONFIG_SYS_83XX_DDR_USES_CS0
4635		Only for 83xx systems. If specified, then DDR should
4636		be configured using CS0 and CS1 instead of CS2 and CS3.
4637
4638- CONFIG_ETHER_ON_FEC[12]
4639		Define to enable FEC[12] on a 8xx series processor.
4640
4641- CONFIG_FEC[12]_PHY
4642		Define to the hardcoded PHY address which corresponds
4643		to the given FEC; i. e.
4644			#define CONFIG_FEC1_PHY 4
4645		means that the PHY with address 4 is connected to FEC1
4646
4647		When set to -1, means to probe for first available.
4648
4649- CONFIG_FEC[12]_PHY_NORXERR
4650		The PHY does not have a RXERR line (RMII only).
4651		(so program the FEC to ignore it).
4652
4653- CONFIG_RMII
4654		Enable RMII mode for all FECs.
4655		Note that this is a global option, we can't
4656		have one FEC in standard MII mode and another in RMII mode.
4657
4658- CONFIG_CRC32_VERIFY
4659		Add a verify option to the crc32 command.
4660		The syntax is:
4661
4662		=> crc32 -v <address> <count> <crc32>
4663
4664		Where address/count indicate a memory area
4665		and crc32 is the correct crc32 which the
4666		area should have.
4667
4668- CONFIG_LOOPW
4669		Add the "loopw" memory command. This only takes effect if
4670		the memory commands are activated globally (CONFIG_CMD_MEM).
4671
4672- CONFIG_MX_CYCLIC
4673		Add the "mdc" and "mwc" memory commands. These are cyclic
4674		"md/mw" commands.
4675		Examples:
4676
4677		=> mdc.b 10 4 500
4678		This command will print 4 bytes (10,11,12,13) each 500 ms.
4679
4680		=> mwc.l 100 12345678 10
4681		This command will write 12345678 to address 100 all 10 ms.
4682
4683		This only takes effect if the memory commands are activated
4684		globally (CONFIG_CMD_MEM).
4685
4686- CONFIG_SKIP_LOWLEVEL_INIT
4687		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4688		low level initializations (like setting up the memory
4689		controller) are omitted and/or U-Boot does not
4690		relocate itself into RAM.
4691
4692		Normally this variable MUST NOT be defined. The only
4693		exception is when U-Boot is loaded (to RAM) by some
4694		other boot loader or by a debugger which performs
4695		these initializations itself.
4696
4697- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4698		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4699		to be skipped. The normal CP15 init (such as enabling the
4700		instruction cache) is still performed.
4701
4702- CONFIG_SPL_BUILD
4703		Modifies the behaviour of start.S when compiling a loader
4704		that is executed before the actual U-Boot. E.g. when
4705		compiling a NAND SPL.
4706
4707- CONFIG_TPL_BUILD
4708		Modifies the behaviour of start.S  when compiling a loader
4709		that is executed after the SPL and before the actual U-Boot.
4710		It is loaded by the SPL.
4711
4712- CONFIG_SYS_MPC85XX_NO_RESETVEC
4713		Only for 85xx systems. If this variable is specified, the section
4714		.resetvec is not kept and the section .bootpg is placed in the
4715		previous 4k of the .text section.
4716
4717- CONFIG_ARCH_MAP_SYSMEM
4718		Generally U-Boot (and in particular the md command) uses
4719		effective address. It is therefore not necessary to regard
4720		U-Boot address as virtual addresses that need to be translated
4721		to physical addresses. However, sandbox requires this, since
4722		it maintains its own little RAM buffer which contains all
4723		addressable memory. This option causes some memory accesses
4724		to be mapped through map_sysmem() / unmap_sysmem().
4725
4726- CONFIG_USE_ARCH_MEMCPY
4727  CONFIG_USE_ARCH_MEMSET
4728		If these options are used a optimized version of memcpy/memset will
4729		be used if available. These functions may be faster under some
4730		conditions but may increase the binary size.
4731
4732- CONFIG_X86_RESET_VECTOR
4733		If defined, the x86 reset vector code is included. This is not
4734		needed when U-Boot is running from Coreboot.
4735
4736- CONFIG_SYS_MPUCLK
4737		Defines the MPU clock speed (in MHz).
4738
4739		NOTE : currently only supported on AM335x platforms.
4740
4741- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4742		Enables the RTC32K OSC on AM33xx based plattforms
4743
4744- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4745		Option to disable subpage write in NAND driver
4746		driver that uses this:
4747		drivers/mtd/nand/davinci_nand.c
4748
4749Freescale QE/FMAN Firmware Support:
4750-----------------------------------
4751
4752The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4753loading of "firmware", which is encoded in the QE firmware binary format.
4754This firmware often needs to be loaded during U-Boot booting, so macros
4755are used to identify the storage device (NOR flash, SPI, etc) and the address
4756within that device.
4757
4758- CONFIG_SYS_FMAN_FW_ADDR
4759	The address in the storage device where the FMAN microcode is located.  The
4760	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4761	is also specified.
4762
4763- CONFIG_SYS_QE_FW_ADDR
4764	The address in the storage device where the QE microcode is located.  The
4765	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4766	is also specified.
4767
4768- CONFIG_SYS_QE_FMAN_FW_LENGTH
4769	The maximum possible size of the firmware.  The firmware binary format
4770	has a field that specifies the actual size of the firmware, but it
4771	might not be possible to read any part of the firmware unless some
4772	local storage is allocated to hold the entire firmware first.
4773
4774- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4775	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4776	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4777	virtual address in NOR flash.
4778
4779- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4780	Specifies that QE/FMAN firmware is located in NAND flash.
4781	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4782
4783- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4784	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4785	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4786
4787- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4788	Specifies that QE/FMAN firmware is located in the remote (master)
4789	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4790	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4791	window->master inbound window->master LAW->the ucode address in
4792	master's memory space.
4793
4794Freescale Layerscape Management Complex Firmware Support:
4795---------------------------------------------------------
4796The Freescale Layerscape Management Complex (MC) supports the loading of
4797"firmware".
4798This firmware often needs to be loaded during U-Boot booting, so macros
4799are used to identify the storage device (NOR flash, SPI, etc) and the address
4800within that device.
4801
4802- CONFIG_FSL_MC_ENET
4803	Enable the MC driver for Layerscape SoCs.
4804
4805Freescale Layerscape Debug Server Support:
4806-------------------------------------------
4807The Freescale Layerscape Debug Server Support supports the loading of
4808"Debug Server firmware" and triggering SP boot-rom.
4809This firmware often needs to be loaded during U-Boot booting.
4810
4811- CONFIG_SYS_MC_RSV_MEM_ALIGN
4812	Define alignment of reserved memory MC requires
4813
4814Reproducible builds
4815-------------------
4816
4817In order to achieve reproducible builds, timestamps used in the U-Boot build
4818process have to be set to a fixed value.
4819
4820This is done using the SOURCE_DATE_EPOCH environment variable.
4821SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4822option for U-Boot or an environment variable in U-Boot.
4823
4824SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4825
4826Building the Software:
4827======================
4828
4829Building U-Boot has been tested in several native build environments
4830and in many different cross environments. Of course we cannot support
4831all possibly existing versions of cross development tools in all
4832(potentially obsolete) versions. In case of tool chain problems we
4833recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4834which is extensively used to build and test U-Boot.
4835
4836If you are not using a native environment, it is assumed that you
4837have GNU cross compiling tools available in your path. In this case,
4838you must set the environment variable CROSS_COMPILE in your shell.
4839Note that no changes to the Makefile or any other source files are
4840necessary. For example using the ELDK on a 4xx CPU, please enter:
4841
4842	$ CROSS_COMPILE=ppc_4xx-
4843	$ export CROSS_COMPILE
4844
4845Note: If you wish to generate Windows versions of the utilities in
4846      the tools directory you can use the MinGW toolchain
4847      (http://www.mingw.org).  Set your HOST tools to the MinGW
4848      toolchain and execute 'make tools'.  For example:
4849
4850       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4851
4852      Binaries such as tools/mkimage.exe will be created which can
4853      be executed on computers running Windows.
4854
4855U-Boot is intended to be simple to build. After installing the
4856sources you must configure U-Boot for one specific board type. This
4857is done by typing:
4858
4859	make NAME_defconfig
4860
4861where "NAME_defconfig" is the name of one of the existing configu-
4862rations; see boards.cfg for supported names.
4863
4864Note: for some board special configuration names may exist; check if
4865      additional information is available from the board vendor; for
4866      instance, the TQM823L systems are available without (standard)
4867      or with LCD support. You can select such additional "features"
4868      when choosing the configuration, i. e.
4869
4870      make TQM823L_defconfig
4871	- will configure for a plain TQM823L, i. e. no LCD support
4872
4873      make TQM823L_LCD_defconfig
4874	- will configure for a TQM823L with U-Boot console on LCD
4875
4876      etc.
4877
4878
4879Finally, type "make all", and you should get some working U-Boot
4880images ready for download to / installation on your system:
4881
4882- "u-boot.bin" is a raw binary image
4883- "u-boot" is an image in ELF binary format
4884- "u-boot.srec" is in Motorola S-Record format
4885
4886By default the build is performed locally and the objects are saved
4887in the source directory. One of the two methods can be used to change
4888this behavior and build U-Boot to some external directory:
4889
48901. Add O= to the make command line invocations:
4891
4892	make O=/tmp/build distclean
4893	make O=/tmp/build NAME_defconfig
4894	make O=/tmp/build all
4895
48962. Set environment variable KBUILD_OUTPUT to point to the desired location:
4897
4898	export KBUILD_OUTPUT=/tmp/build
4899	make distclean
4900	make NAME_defconfig
4901	make all
4902
4903Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4904variable.
4905
4906
4907Please be aware that the Makefiles assume you are using GNU make, so
4908for instance on NetBSD you might need to use "gmake" instead of
4909native "make".
4910
4911
4912If the system board that you have is not listed, then you will need
4913to port U-Boot to your hardware platform. To do this, follow these
4914steps:
4915
49161.  Create a new directory to hold your board specific code. Add any
4917    files you need. In your board directory, you will need at least
4918    the "Makefile" and a "<board>.c".
49192.  Create a new configuration file "include/configs/<board>.h" for
4920    your board.
49213.  If you're porting U-Boot to a new CPU, then also create a new
4922    directory to hold your CPU specific code. Add any files you need.
49234.  Run "make <board>_defconfig" with your new name.
49245.  Type "make", and you should get a working "u-boot.srec" file
4925    to be installed on your target system.
49266.  Debug and solve any problems that might arise.
4927    [Of course, this last step is much harder than it sounds.]
4928
4929
4930Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4931==============================================================
4932
4933If you have modified U-Boot sources (for instance added a new board
4934or support for new devices, a new CPU, etc.) you are expected to
4935provide feedback to the other developers. The feedback normally takes
4936the form of a "patch", i. e. a context diff against a certain (latest
4937official or latest in the git repository) version of U-Boot sources.
4938
4939But before you submit such a patch, please verify that your modifi-
4940cation did not break existing code. At least make sure that *ALL* of
4941the supported boards compile WITHOUT ANY compiler warnings. To do so,
4942just run the buildman script (tools/buildman/buildman), which will
4943configure and build U-Boot for ALL supported system. Be warned, this
4944will take a while. Please see the buildman README, or run 'buildman -H'
4945for documentation.
4946
4947
4948See also "U-Boot Porting Guide" below.
4949
4950
4951Monitor Commands - Overview:
4952============================
4953
4954go	- start application at address 'addr'
4955run	- run commands in an environment variable
4956bootm	- boot application image from memory
4957bootp	- boot image via network using BootP/TFTP protocol
4958bootz   - boot zImage from memory
4959tftpboot- boot image via network using TFTP protocol
4960	       and env variables "ipaddr" and "serverip"
4961	       (and eventually "gatewayip")
4962tftpput - upload a file via network using TFTP protocol
4963rarpboot- boot image via network using RARP/TFTP protocol
4964diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4965loads	- load S-Record file over serial line
4966loadb	- load binary file over serial line (kermit mode)
4967md	- memory display
4968mm	- memory modify (auto-incrementing)
4969nm	- memory modify (constant address)
4970mw	- memory write (fill)
4971cp	- memory copy
4972cmp	- memory compare
4973crc32	- checksum calculation
4974i2c	- I2C sub-system
4975sspi	- SPI utility commands
4976base	- print or set address offset
4977printenv- print environment variables
4978setenv	- set environment variables
4979saveenv - save environment variables to persistent storage
4980protect - enable or disable FLASH write protection
4981erase	- erase FLASH memory
4982flinfo	- print FLASH memory information
4983nand	- NAND memory operations (see doc/README.nand)
4984bdinfo	- print Board Info structure
4985iminfo	- print header information for application image
4986coninfo - print console devices and informations
4987ide	- IDE sub-system
4988loop	- infinite loop on address range
4989loopw	- infinite write loop on address range
4990mtest	- simple RAM test
4991icache	- enable or disable instruction cache
4992dcache	- enable or disable data cache
4993reset	- Perform RESET of the CPU
4994echo	- echo args to console
4995version - print monitor version
4996help	- print online help
4997?	- alias for 'help'
4998
4999
5000Monitor Commands - Detailed Description:
5001========================================
5002
5003TODO.
5004
5005For now: just type "help <command>".
5006
5007
5008Environment Variables:
5009======================
5010
5011U-Boot supports user configuration using Environment Variables which
5012can be made persistent by saving to Flash memory.
5013
5014Environment Variables are set using "setenv", printed using
5015"printenv", and saved to Flash using "saveenv". Using "setenv"
5016without a value can be used to delete a variable from the
5017environment. As long as you don't save the environment you are
5018working with an in-memory copy. In case the Flash area containing the
5019environment is erased by accident, a default environment is provided.
5020
5021Some configuration options can be set using Environment Variables.
5022
5023List of environment variables (most likely not complete):
5024
5025  baudrate	- see CONFIG_BAUDRATE
5026
5027  bootdelay	- see CONFIG_BOOTDELAY
5028
5029  bootcmd	- see CONFIG_BOOTCOMMAND
5030
5031  bootargs	- Boot arguments when booting an RTOS image
5032
5033  bootfile	- Name of the image to load with TFTP
5034
5035  bootm_low	- Memory range available for image processing in the bootm
5036		  command can be restricted. This variable is given as
5037		  a hexadecimal number and defines lowest address allowed
5038		  for use by the bootm command. See also "bootm_size"
5039		  environment variable. Address defined by "bootm_low" is
5040		  also the base of the initial memory mapping for the Linux
5041		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5042		  bootm_mapsize.
5043
5044  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5045		  This variable is given as a hexadecimal number and it
5046		  defines the size of the memory region starting at base
5047		  address bootm_low that is accessible by the Linux kernel
5048		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5049		  as the default value if it is defined, and bootm_size is
5050		  used otherwise.
5051
5052  bootm_size	- Memory range available for image processing in the bootm
5053		  command can be restricted. This variable is given as
5054		  a hexadecimal number and defines the size of the region
5055		  allowed for use by the bootm command. See also "bootm_low"
5056		  environment variable.
5057
5058  updatefile	- Location of the software update file on a TFTP server, used
5059		  by the automatic software update feature. Please refer to
5060		  documentation in doc/README.update for more details.
5061
5062  autoload	- if set to "no" (any string beginning with 'n'),
5063		  "bootp" will just load perform a lookup of the
5064		  configuration from the BOOTP server, but not try to
5065		  load any image using TFTP
5066
5067  autostart	- if set to "yes", an image loaded using the "bootp",
5068		  "rarpboot", "tftpboot" or "diskboot" commands will
5069		  be automatically started (by internally calling
5070		  "bootm")
5071
5072		  If set to "no", a standalone image passed to the
5073		  "bootm" command will be copied to the load address
5074		  (and eventually uncompressed), but NOT be started.
5075		  This can be used to load and uncompress arbitrary
5076		  data.
5077
5078  fdt_high	- if set this restricts the maximum address that the
5079		  flattened device tree will be copied into upon boot.
5080		  For example, if you have a system with 1 GB memory
5081		  at physical address 0x10000000, while Linux kernel
5082		  only recognizes the first 704 MB as low memory, you
5083		  may need to set fdt_high as 0x3C000000 to have the
5084		  device tree blob be copied to the maximum address
5085		  of the 704 MB low memory, so that Linux kernel can
5086		  access it during the boot procedure.
5087
5088		  If this is set to the special value 0xFFFFFFFF then
5089		  the fdt will not be copied at all on boot.  For this
5090		  to work it must reside in writable memory, have
5091		  sufficient padding on the end of it for u-boot to
5092		  add the information it needs into it, and the memory
5093		  must be accessible by the kernel.
5094
5095  fdtcontroladdr- if set this is the address of the control flattened
5096		  device tree used by U-Boot when CONFIG_OF_CONTROL is
5097		  defined.
5098
5099  i2cfast	- (PPC405GP|PPC405EP only)
5100		  if set to 'y' configures Linux I2C driver for fast
5101		  mode (400kHZ). This environment variable is used in
5102		  initialization code. So, for changes to be effective
5103		  it must be saved and board must be reset.
5104
5105  initrd_high	- restrict positioning of initrd images:
5106		  If this variable is not set, initrd images will be
5107		  copied to the highest possible address in RAM; this
5108		  is usually what you want since it allows for
5109		  maximum initrd size. If for some reason you want to
5110		  make sure that the initrd image is loaded below the
5111		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5112		  variable to a value of "no" or "off" or "0".
5113		  Alternatively, you can set it to a maximum upper
5114		  address to use (U-Boot will still check that it
5115		  does not overwrite the U-Boot stack and data).
5116
5117		  For instance, when you have a system with 16 MB
5118		  RAM, and want to reserve 4 MB from use by Linux,
5119		  you can do this by adding "mem=12M" to the value of
5120		  the "bootargs" variable. However, now you must make
5121		  sure that the initrd image is placed in the first
5122		  12 MB as well - this can be done with
5123
5124		  setenv initrd_high 00c00000
5125
5126		  If you set initrd_high to 0xFFFFFFFF, this is an
5127		  indication to U-Boot that all addresses are legal
5128		  for the Linux kernel, including addresses in flash
5129		  memory. In this case U-Boot will NOT COPY the
5130		  ramdisk at all. This may be useful to reduce the
5131		  boot time on your system, but requires that this
5132		  feature is supported by your Linux kernel.
5133
5134  ipaddr	- IP address; needed for tftpboot command
5135
5136  loadaddr	- Default load address for commands like "bootp",
5137		  "rarpboot", "tftpboot", "loadb" or "diskboot"
5138
5139  loads_echo	- see CONFIG_LOADS_ECHO
5140
5141  serverip	- TFTP server IP address; needed for tftpboot command
5142
5143  bootretry	- see CONFIG_BOOT_RETRY_TIME
5144
5145  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5146
5147  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5148
5149  ethprime	- controls which interface is used first.
5150
5151  ethact	- controls which interface is currently active.
5152		  For example you can do the following
5153
5154		  => setenv ethact FEC
5155		  => ping 192.168.0.1 # traffic sent on FEC
5156		  => setenv ethact SCC
5157		  => ping 10.0.0.1 # traffic sent on SCC
5158
5159  ethrotate	- When set to "no" U-Boot does not go through all
5160		  available network interfaces.
5161		  It just stays at the currently selected interface.
5162
5163  netretry	- When set to "no" each network operation will
5164		  either succeed or fail without retrying.
5165		  When set to "once" the network operation will
5166		  fail when all the available network interfaces
5167		  are tried once without success.
5168		  Useful on scripts which control the retry operation
5169		  themselves.
5170
5171  npe_ucode	- set load address for the NPE microcode
5172
5173  silent_linux  - If set then Linux will be told to boot silently, by
5174		  changing the console to be empty. If "yes" it will be
5175		  made silent. If "no" it will not be made silent. If
5176		  unset, then it will be made silent if the U-Boot console
5177		  is silent.
5178
5179  tftpsrcp	- If this is set, the value is used for TFTP's
5180		  UDP source port.
5181
5182  tftpdstp	- If this is set, the value is used for TFTP's UDP
5183		  destination port instead of the Well Know Port 69.
5184
5185  tftpblocksize - Block size to use for TFTP transfers; if not set,
5186		  we use the TFTP server's default block size
5187
5188  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5189		  seconds, minimum value is 1000 = 1 second). Defines
5190		  when a packet is considered to be lost so it has to
5191		  be retransmitted. The default is 5000 = 5 seconds.
5192		  Lowering this value may make downloads succeed
5193		  faster in networks with high packet loss rates or
5194		  with unreliable TFTP servers.
5195
5196  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
5197		  unit, minimum value = 0). Defines how many timeouts
5198		  can happen during a single file transfer before that
5199		  transfer is aborted. The default is 10, and 0 means
5200		  'no timeouts allowed'. Increasing this value may help
5201		  downloads succeed with high packet loss rates, or with
5202		  unreliable TFTP servers or client hardware.
5203
5204  vlan		- When set to a value < 4095 the traffic over
5205		  Ethernet is encapsulated/received over 802.1q
5206		  VLAN tagged frames.
5207
5208  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
5209		  Unsigned value, in milliseconds. If not set, the period will
5210		  be either the default (28000), or a value based on
5211		  CONFIG_NET_RETRY_COUNT, if defined. This value has
5212		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
5213
5214The following image location variables contain the location of images
5215used in booting. The "Image" column gives the role of the image and is
5216not an environment variable name. The other columns are environment
5217variable names. "File Name" gives the name of the file on a TFTP
5218server, "RAM Address" gives the location in RAM the image will be
5219loaded to, and "Flash Location" gives the image's address in NOR
5220flash or offset in NAND flash.
5221
5222*Note* - these variables don't have to be defined for all boards, some
5223boards currently use other variables for these purposes, and some
5224boards use these variables for other purposes.
5225
5226Image		    File Name	     RAM Address       Flash Location
5227-----		    ---------	     -----------       --------------
5228u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5229Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5230device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5231ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5232
5233The following environment variables may be used and automatically
5234updated by the network boot commands ("bootp" and "rarpboot"),
5235depending the information provided by your boot server:
5236
5237  bootfile	- see above
5238  dnsip		- IP address of your Domain Name Server
5239  dnsip2	- IP address of your secondary Domain Name Server
5240  gatewayip	- IP address of the Gateway (Router) to use
5241  hostname	- Target hostname
5242  ipaddr	- see above
5243  netmask	- Subnet Mask
5244  rootpath	- Pathname of the root filesystem on the NFS server
5245  serverip	- see above
5246
5247
5248There are two special Environment Variables:
5249
5250  serial#	- contains hardware identification information such
5251		  as type string and/or serial number
5252  ethaddr	- Ethernet address
5253
5254These variables can be set only once (usually during manufacturing of
5255the board). U-Boot refuses to delete or overwrite these variables
5256once they have been set once.
5257
5258
5259Further special Environment Variables:
5260
5261  ver		- Contains the U-Boot version string as printed
5262		  with the "version" command. This variable is
5263		  readonly (see CONFIG_VERSION_VARIABLE).
5264
5265
5266Please note that changes to some configuration parameters may take
5267only effect after the next boot (yes, that's just like Windoze :-).
5268
5269
5270Callback functions for environment variables:
5271---------------------------------------------
5272
5273For some environment variables, the behavior of u-boot needs to change
5274when their values are changed.  This functionality allows functions to
5275be associated with arbitrary variables.  On creation, overwrite, or
5276deletion, the callback will provide the opportunity for some side
5277effect to happen or for the change to be rejected.
5278
5279The callbacks are named and associated with a function using the
5280U_BOOT_ENV_CALLBACK macro in your board or driver code.
5281
5282These callbacks are associated with variables in one of two ways.  The
5283static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5284in the board configuration to a string that defines a list of
5285associations.  The list must be in the following format:
5286
5287	entry = variable_name[:callback_name]
5288	list = entry[,list]
5289
5290If the callback name is not specified, then the callback is deleted.
5291Spaces are also allowed anywhere in the list.
5292
5293Callbacks can also be associated by defining the ".callbacks" variable
5294with the same list format above.  Any association in ".callbacks" will
5295override any association in the static list. You can define
5296CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5297".callbacks" environment variable in the default or embedded environment.
5298
5299If CONFIG_REGEX is defined, the variable_name above is evaluated as a
5300regular expression. This allows multiple variables to be connected to
5301the same callback without explicitly listing them all out.
5302
5303
5304Command Line Parsing:
5305=====================
5306
5307There are two different command line parsers available with U-Boot:
5308the old "simple" one, and the much more powerful "hush" shell:
5309
5310Old, simple command line parser:
5311--------------------------------
5312
5313- supports environment variables (through setenv / saveenv commands)
5314- several commands on one line, separated by ';'
5315- variable substitution using "... ${name} ..." syntax
5316- special characters ('$', ';') can be escaped by prefixing with '\',
5317  for example:
5318	setenv bootcmd bootm \${address}
5319- You can also escape text by enclosing in single apostrophes, for example:
5320	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5321
5322Hush shell:
5323-----------
5324
5325- similar to Bourne shell, with control structures like
5326  if...then...else...fi, for...do...done; while...do...done,
5327  until...do...done, ...
5328- supports environment ("global") variables (through setenv / saveenv
5329  commands) and local shell variables (through standard shell syntax
5330  "name=value"); only environment variables can be used with "run"
5331  command
5332
5333General rules:
5334--------------
5335
5336(1) If a command line (or an environment variable executed by a "run"
5337    command) contains several commands separated by semicolon, and
5338    one of these commands fails, then the remaining commands will be
5339    executed anyway.
5340
5341(2) If you execute several variables with one call to run (i. e.
5342    calling run with a list of variables as arguments), any failing
5343    command will cause "run" to terminate, i. e. the remaining
5344    variables are not executed.
5345
5346Note for Redundant Ethernet Interfaces:
5347=======================================
5348
5349Some boards come with redundant Ethernet interfaces; U-Boot supports
5350such configurations and is capable of automatic selection of a
5351"working" interface when needed. MAC assignment works as follows:
5352
5353Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5354MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5355"eth1addr" (=>eth1), "eth2addr", ...
5356
5357If the network interface stores some valid MAC address (for instance
5358in SROM), this is used as default address if there is NO correspon-
5359ding setting in the environment; if the corresponding environment
5360variable is set, this overrides the settings in the card; that means:
5361
5362o If the SROM has a valid MAC address, and there is no address in the
5363  environment, the SROM's address is used.
5364
5365o If there is no valid address in the SROM, and a definition in the
5366  environment exists, then the value from the environment variable is
5367  used.
5368
5369o If both the SROM and the environment contain a MAC address, and
5370  both addresses are the same, this MAC address is used.
5371
5372o If both the SROM and the environment contain a MAC address, and the
5373  addresses differ, the value from the environment is used and a
5374  warning is printed.
5375
5376o If neither SROM nor the environment contain a MAC address, an error
5377  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5378  a random, locally-assigned MAC is used.
5379
5380If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5381will be programmed into hardware as part of the initialization process.	 This
5382may be skipped by setting the appropriate 'ethmacskip' environment variable.
5383The naming convention is as follows:
5384"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5385
5386Image Formats:
5387==============
5388
5389U-Boot is capable of booting (and performing other auxiliary operations on)
5390images in two formats:
5391
5392New uImage format (FIT)
5393-----------------------
5394
5395Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5396to Flattened Device Tree). It allows the use of images with multiple
5397components (several kernels, ramdisks, etc.), with contents protected by
5398SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5399
5400
5401Old uImage format
5402-----------------
5403
5404Old image format is based on binary files which can be basically anything,
5405preceded by a special header; see the definitions in include/image.h for
5406details; basically, the header defines the following image properties:
5407
5408* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5409  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5410  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5411  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5412  INTEGRITY).
5413* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5414  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5415  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5416* Compression Type (uncompressed, gzip, bzip2)
5417* Load Address
5418* Entry Point
5419* Image Name
5420* Image Timestamp
5421
5422The header is marked by a special Magic Number, and both the header
5423and the data portions of the image are secured against corruption by
5424CRC32 checksums.
5425
5426
5427Linux Support:
5428==============
5429
5430Although U-Boot should support any OS or standalone application
5431easily, the main focus has always been on Linux during the design of
5432U-Boot.
5433
5434U-Boot includes many features that so far have been part of some
5435special "boot loader" code within the Linux kernel. Also, any
5436"initrd" images to be used are no longer part of one big Linux image;
5437instead, kernel and "initrd" are separate images. This implementation
5438serves several purposes:
5439
5440- the same features can be used for other OS or standalone
5441  applications (for instance: using compressed images to reduce the
5442  Flash memory footprint)
5443
5444- it becomes much easier to port new Linux kernel versions because
5445  lots of low-level, hardware dependent stuff are done by U-Boot
5446
5447- the same Linux kernel image can now be used with different "initrd"
5448  images; of course this also means that different kernel images can
5449  be run with the same "initrd". This makes testing easier (you don't
5450  have to build a new "zImage.initrd" Linux image when you just
5451  change a file in your "initrd"). Also, a field-upgrade of the
5452  software is easier now.
5453
5454
5455Linux HOWTO:
5456============
5457
5458Porting Linux to U-Boot based systems:
5459---------------------------------------
5460
5461U-Boot cannot save you from doing all the necessary modifications to
5462configure the Linux device drivers for use with your target hardware
5463(no, we don't intend to provide a full virtual machine interface to
5464Linux :-).
5465
5466But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5467
5468Just make sure your machine specific header file (for instance
5469include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5470Information structure as we define in include/asm-<arch>/u-boot.h,
5471and make sure that your definition of IMAP_ADDR uses the same value
5472as your U-Boot configuration in CONFIG_SYS_IMMR.
5473
5474Note that U-Boot now has a driver model, a unified model for drivers.
5475If you are adding a new driver, plumb it into driver model. If there
5476is no uclass available, you are encouraged to create one. See
5477doc/driver-model.
5478
5479
5480Configuring the Linux kernel:
5481-----------------------------
5482
5483No specific requirements for U-Boot. Make sure you have some root
5484device (initial ramdisk, NFS) for your target system.
5485
5486
5487Building a Linux Image:
5488-----------------------
5489
5490With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5491not used. If you use recent kernel source, a new build target
5492"uImage" will exist which automatically builds an image usable by
5493U-Boot. Most older kernels also have support for a "pImage" target,
5494which was introduced for our predecessor project PPCBoot and uses a
5495100% compatible format.
5496
5497Example:
5498
5499	make TQM850L_defconfig
5500	make oldconfig
5501	make dep
5502	make uImage
5503
5504The "uImage" build target uses a special tool (in 'tools/mkimage') to
5505encapsulate a compressed Linux kernel image with header	 information,
5506CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5507
5508* build a standard "vmlinux" kernel image (in ELF binary format):
5509
5510* convert the kernel into a raw binary image:
5511
5512	${CROSS_COMPILE}-objcopy -O binary \
5513				 -R .note -R .comment \
5514				 -S vmlinux linux.bin
5515
5516* compress the binary image:
5517
5518	gzip -9 linux.bin
5519
5520* package compressed binary image for U-Boot:
5521
5522	mkimage -A ppc -O linux -T kernel -C gzip \
5523		-a 0 -e 0 -n "Linux Kernel Image" \
5524		-d linux.bin.gz uImage
5525
5526
5527The "mkimage" tool can also be used to create ramdisk images for use
5528with U-Boot, either separated from the Linux kernel image, or
5529combined into one file. "mkimage" encapsulates the images with a 64
5530byte header containing information about target architecture,
5531operating system, image type, compression method, entry points, time
5532stamp, CRC32 checksums, etc.
5533
5534"mkimage" can be called in two ways: to verify existing images and
5535print the header information, or to build new images.
5536
5537In the first form (with "-l" option) mkimage lists the information
5538contained in the header of an existing U-Boot image; this includes
5539checksum verification:
5540
5541	tools/mkimage -l image
5542	  -l ==> list image header information
5543
5544The second form (with "-d" option) is used to build a U-Boot image
5545from a "data file" which is used as image payload:
5546
5547	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5548		      -n name -d data_file image
5549	  -A ==> set architecture to 'arch'
5550	  -O ==> set operating system to 'os'
5551	  -T ==> set image type to 'type'
5552	  -C ==> set compression type 'comp'
5553	  -a ==> set load address to 'addr' (hex)
5554	  -e ==> set entry point to 'ep' (hex)
5555	  -n ==> set image name to 'name'
5556	  -d ==> use image data from 'datafile'
5557
5558Right now, all Linux kernels for PowerPC systems use the same load
5559address (0x00000000), but the entry point address depends on the
5560kernel version:
5561
5562- 2.2.x kernels have the entry point at 0x0000000C,
5563- 2.3.x and later kernels have the entry point at 0x00000000.
5564
5565So a typical call to build a U-Boot image would read:
5566
5567	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5568	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5569	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5570	> examples/uImage.TQM850L
5571	Image Name:   2.4.4 kernel for TQM850L
5572	Created:      Wed Jul 19 02:34:59 2000
5573	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5574	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5575	Load Address: 0x00000000
5576	Entry Point:  0x00000000
5577
5578To verify the contents of the image (or check for corruption):
5579
5580	-> tools/mkimage -l examples/uImage.TQM850L
5581	Image Name:   2.4.4 kernel for TQM850L
5582	Created:      Wed Jul 19 02:34:59 2000
5583	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5584	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5585	Load Address: 0x00000000
5586	Entry Point:  0x00000000
5587
5588NOTE: for embedded systems where boot time is critical you can trade
5589speed for memory and install an UNCOMPRESSED image instead: this
5590needs more space in Flash, but boots much faster since it does not
5591need to be uncompressed:
5592
5593	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5594	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5595	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5596	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5597	> examples/uImage.TQM850L-uncompressed
5598	Image Name:   2.4.4 kernel for TQM850L
5599	Created:      Wed Jul 19 02:34:59 2000
5600	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5601	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5602	Load Address: 0x00000000
5603	Entry Point:  0x00000000
5604
5605
5606Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5607when your kernel is intended to use an initial ramdisk:
5608
5609	-> tools/mkimage -n 'Simple Ramdisk Image' \
5610	> -A ppc -O linux -T ramdisk -C gzip \
5611	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5612	Image Name:   Simple Ramdisk Image
5613	Created:      Wed Jan 12 14:01:50 2000
5614	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5615	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5616	Load Address: 0x00000000
5617	Entry Point:  0x00000000
5618
5619The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5620option performs the converse operation of the mkimage's second form (the "-d"
5621option). Given an image built by mkimage, the dumpimage extracts a "data file"
5622from the image:
5623
5624	tools/dumpimage -i image -T type -p position data_file
5625	  -i ==> extract from the 'image' a specific 'data_file'
5626	  -T ==> set image type to 'type'
5627	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5628
5629
5630Installing a Linux Image:
5631-------------------------
5632
5633To downloading a U-Boot image over the serial (console) interface,
5634you must convert the image to S-Record format:
5635
5636	objcopy -I binary -O srec examples/image examples/image.srec
5637
5638The 'objcopy' does not understand the information in the U-Boot
5639image header, so the resulting S-Record file will be relative to
5640address 0x00000000. To load it to a given address, you need to
5641specify the target address as 'offset' parameter with the 'loads'
5642command.
5643
5644Example: install the image to address 0x40100000 (which on the
5645TQM8xxL is in the first Flash bank):
5646
5647	=> erase 40100000 401FFFFF
5648
5649	.......... done
5650	Erased 8 sectors
5651
5652	=> loads 40100000
5653	## Ready for S-Record download ...
5654	~>examples/image.srec
5655	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5656	...
5657	15989 15990 15991 15992
5658	[file transfer complete]
5659	[connected]
5660	## Start Addr = 0x00000000
5661
5662
5663You can check the success of the download using the 'iminfo' command;
5664this includes a checksum verification so you can be sure no data
5665corruption happened:
5666
5667	=> imi 40100000
5668
5669	## Checking Image at 40100000 ...
5670	   Image Name:	 2.2.13 for initrd on TQM850L
5671	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5672	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5673	   Load Address: 00000000
5674	   Entry Point:	 0000000c
5675	   Verifying Checksum ... OK
5676
5677
5678Boot Linux:
5679-----------
5680
5681The "bootm" command is used to boot an application that is stored in
5682memory (RAM or Flash). In case of a Linux kernel image, the contents
5683of the "bootargs" environment variable is passed to the kernel as
5684parameters. You can check and modify this variable using the
5685"printenv" and "setenv" commands:
5686
5687
5688	=> printenv bootargs
5689	bootargs=root=/dev/ram
5690
5691	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5692
5693	=> printenv bootargs
5694	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5695
5696	=> bootm 40020000
5697	## Booting Linux kernel at 40020000 ...
5698	   Image Name:	 2.2.13 for NFS on TQM850L
5699	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5700	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5701	   Load Address: 00000000
5702	   Entry Point:	 0000000c
5703	   Verifying Checksum ... OK
5704	   Uncompressing Kernel Image ... OK
5705	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
5706	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5707	time_init: decrementer frequency = 187500000/60
5708	Calibrating delay loop... 49.77 BogoMIPS
5709	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5710	...
5711
5712If you want to boot a Linux kernel with initial RAM disk, you pass
5713the memory addresses of both the kernel and the initrd image (PPBCOOT
5714format!) to the "bootm" command:
5715
5716	=> imi 40100000 40200000
5717
5718	## Checking Image at 40100000 ...
5719	   Image Name:	 2.2.13 for initrd on TQM850L
5720	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5721	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5722	   Load Address: 00000000
5723	   Entry Point:	 0000000c
5724	   Verifying Checksum ... OK
5725
5726	## Checking Image at 40200000 ...
5727	   Image Name:	 Simple Ramdisk Image
5728	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5729	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5730	   Load Address: 00000000
5731	   Entry Point:	 00000000
5732	   Verifying Checksum ... OK
5733
5734	=> bootm 40100000 40200000
5735	## Booting Linux kernel at 40100000 ...
5736	   Image Name:	 2.2.13 for initrd on TQM850L
5737	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5738	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5739	   Load Address: 00000000
5740	   Entry Point:	 0000000c
5741	   Verifying Checksum ... OK
5742	   Uncompressing Kernel Image ... OK
5743	## Loading RAMDisk Image at 40200000 ...
5744	   Image Name:	 Simple Ramdisk Image
5745	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5746	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5747	   Load Address: 00000000
5748	   Entry Point:	 00000000
5749	   Verifying Checksum ... OK
5750	   Loading Ramdisk ... OK
5751	Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
5752	Boot arguments: root=/dev/ram
5753	time_init: decrementer frequency = 187500000/60
5754	Calibrating delay loop... 49.77 BogoMIPS
5755	...
5756	RAMDISK: Compressed image found at block 0
5757	VFS: Mounted root (ext2 filesystem).
5758
5759	bash#
5760
5761Boot Linux and pass a flat device tree:
5762-----------
5763
5764First, U-Boot must be compiled with the appropriate defines. See the section
5765titled "Linux Kernel Interface" above for a more in depth explanation. The
5766following is an example of how to start a kernel and pass an updated
5767flat device tree:
5768
5769=> print oftaddr
5770oftaddr=0x300000
5771=> print oft
5772oft=oftrees/mpc8540ads.dtb
5773=> tftp $oftaddr $oft
5774Speed: 1000, full duplex
5775Using TSEC0 device
5776TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5777Filename 'oftrees/mpc8540ads.dtb'.
5778Load address: 0x300000
5779Loading: #
5780done
5781Bytes transferred = 4106 (100a hex)
5782=> tftp $loadaddr $bootfile
5783Speed: 1000, full duplex
5784Using TSEC0 device
5785TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5786Filename 'uImage'.
5787Load address: 0x200000
5788Loading:############
5789done
5790Bytes transferred = 1029407 (fb51f hex)
5791=> print loadaddr
5792loadaddr=200000
5793=> print oftaddr
5794oftaddr=0x300000
5795=> bootm $loadaddr - $oftaddr
5796## Booting image at 00200000 ...
5797   Image Name:	 Linux-2.6.17-dirty
5798   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5799   Data Size:	 1029343 Bytes = 1005.2 kB
5800   Load Address: 00000000
5801   Entry Point:	 00000000
5802   Verifying Checksum ... OK
5803   Uncompressing Kernel Image ... OK
5804Booting using flat device tree at 0x300000
5805Using MPC85xx ADS machine description
5806Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5807[snip]
5808
5809
5810More About U-Boot Image Types:
5811------------------------------
5812
5813U-Boot supports the following image types:
5814
5815   "Standalone Programs" are directly runnable in the environment
5816	provided by U-Boot; it is expected that (if they behave
5817	well) you can continue to work in U-Boot after return from
5818	the Standalone Program.
5819   "OS Kernel Images" are usually images of some Embedded OS which
5820	will take over control completely. Usually these programs
5821	will install their own set of exception handlers, device
5822	drivers, set up the MMU, etc. - this means, that you cannot
5823	expect to re-enter U-Boot except by resetting the CPU.
5824   "RAMDisk Images" are more or less just data blocks, and their
5825	parameters (address, size) are passed to an OS kernel that is
5826	being started.
5827   "Multi-File Images" contain several images, typically an OS
5828	(Linux) kernel image and one or more data images like
5829	RAMDisks. This construct is useful for instance when you want
5830	to boot over the network using BOOTP etc., where the boot
5831	server provides just a single image file, but you want to get
5832	for instance an OS kernel and a RAMDisk image.
5833
5834	"Multi-File Images" start with a list of image sizes, each
5835	image size (in bytes) specified by an "uint32_t" in network
5836	byte order. This list is terminated by an "(uint32_t)0".
5837	Immediately after the terminating 0 follow the images, one by
5838	one, all aligned on "uint32_t" boundaries (size rounded up to
5839	a multiple of 4 bytes).
5840
5841   "Firmware Images" are binary images containing firmware (like
5842	U-Boot or FPGA images) which usually will be programmed to
5843	flash memory.
5844
5845   "Script files" are command sequences that will be executed by
5846	U-Boot's command interpreter; this feature is especially
5847	useful when you configure U-Boot to use a real shell (hush)
5848	as command interpreter.
5849
5850Booting the Linux zImage:
5851-------------------------
5852
5853On some platforms, it's possible to boot Linux zImage. This is done
5854using the "bootz" command. The syntax of "bootz" command is the same
5855as the syntax of "bootm" command.
5856
5857Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5858kernel with raw initrd images. The syntax is slightly different, the
5859address of the initrd must be augmented by it's size, in the following
5860format: "<initrd addres>:<initrd size>".
5861
5862
5863Standalone HOWTO:
5864=================
5865
5866One of the features of U-Boot is that you can dynamically load and
5867run "standalone" applications, which can use some resources of
5868U-Boot like console I/O functions or interrupt services.
5869
5870Two simple examples are included with the sources:
5871
5872"Hello World" Demo:
5873-------------------
5874
5875'examples/hello_world.c' contains a small "Hello World" Demo
5876application; it is automatically compiled when you build U-Boot.
5877It's configured to run at address 0x00040004, so you can play with it
5878like that:
5879
5880	=> loads
5881	## Ready for S-Record download ...
5882	~>examples/hello_world.srec
5883	1 2 3 4 5 6 7 8 9 10 11 ...
5884	[file transfer complete]
5885	[connected]
5886	## Start Addr = 0x00040004
5887
5888	=> go 40004 Hello World! This is a test.
5889	## Starting application at 0x00040004 ...
5890	Hello World
5891	argc = 7
5892	argv[0] = "40004"
5893	argv[1] = "Hello"
5894	argv[2] = "World!"
5895	argv[3] = "This"
5896	argv[4] = "is"
5897	argv[5] = "a"
5898	argv[6] = "test."
5899	argv[7] = "<NULL>"
5900	Hit any key to exit ...
5901
5902	## Application terminated, rc = 0x0
5903
5904Another example, which demonstrates how to register a CPM interrupt
5905handler with the U-Boot code, can be found in 'examples/timer.c'.
5906Here, a CPM timer is set up to generate an interrupt every second.
5907The interrupt service routine is trivial, just printing a '.'
5908character, but this is just a demo program. The application can be
5909controlled by the following keys:
5910
5911	? - print current values og the CPM Timer registers
5912	b - enable interrupts and start timer
5913	e - stop timer and disable interrupts
5914	q - quit application
5915
5916	=> loads
5917	## Ready for S-Record download ...
5918	~>examples/timer.srec
5919	1 2 3 4 5 6 7 8 9 10 11 ...
5920	[file transfer complete]
5921	[connected]
5922	## Start Addr = 0x00040004
5923
5924	=> go 40004
5925	## Starting application at 0x00040004 ...
5926	TIMERS=0xfff00980
5927	Using timer 1
5928	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5929
5930Hit 'b':
5931	[q, b, e, ?] Set interval 1000000 us
5932	Enabling timer
5933Hit '?':
5934	[q, b, e, ?] ........
5935	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5936Hit '?':
5937	[q, b, e, ?] .
5938	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5939Hit '?':
5940	[q, b, e, ?] .
5941	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5942Hit '?':
5943	[q, b, e, ?] .
5944	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5945Hit 'e':
5946	[q, b, e, ?] ...Stopping timer
5947Hit 'q':
5948	[q, b, e, ?] ## Application terminated, rc = 0x0
5949
5950
5951Minicom warning:
5952================
5953
5954Over time, many people have reported problems when trying to use the
5955"minicom" terminal emulation program for serial download. I (wd)
5956consider minicom to be broken, and recommend not to use it. Under
5957Unix, I recommend to use C-Kermit for general purpose use (and
5958especially for kermit binary protocol download ("loadb" command), and
5959use "cu" for S-Record download ("loads" command).  See
5960http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5961for help with kermit.
5962
5963
5964Nevertheless, if you absolutely want to use it try adding this
5965configuration to your "File transfer protocols" section:
5966
5967	   Name	   Program			Name U/D FullScr IO-Red. Multi
5968	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5969	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5970
5971
5972NetBSD Notes:
5973=============
5974
5975Starting at version 0.9.2, U-Boot supports NetBSD both as host
5976(build U-Boot) and target system (boots NetBSD/mpc8xx).
5977
5978Building requires a cross environment; it is known to work on
5979NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5980need gmake since the Makefiles are not compatible with BSD make).
5981Note that the cross-powerpc package does not install include files;
5982attempting to build U-Boot will fail because <machine/ansi.h> is
5983missing.  This file has to be installed and patched manually:
5984
5985	# cd /usr/pkg/cross/powerpc-netbsd/include
5986	# mkdir powerpc
5987	# ln -s powerpc machine
5988	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5989	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5990
5991Native builds *don't* work due to incompatibilities between native
5992and U-Boot include files.
5993
5994Booting assumes that (the first part of) the image booted is a
5995stage-2 loader which in turn loads and then invokes the kernel
5996proper. Loader sources will eventually appear in the NetBSD source
5997tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5998meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5999
6000
6001Implementation Internals:
6002=========================
6003
6004The following is not intended to be a complete description of every
6005implementation detail. However, it should help to understand the
6006inner workings of U-Boot and make it easier to port it to custom
6007hardware.
6008
6009
6010Initial Stack, Global Data:
6011---------------------------
6012
6013The implementation of U-Boot is complicated by the fact that U-Boot
6014starts running out of ROM (flash memory), usually without access to
6015system RAM (because the memory controller is not initialized yet).
6016This means that we don't have writable Data or BSS segments, and BSS
6017is not initialized as zero. To be able to get a C environment working
6018at all, we have to allocate at least a minimal stack. Implementation
6019options for this are defined and restricted by the CPU used: Some CPU
6020models provide on-chip memory (like the IMMR area on MPC8xx and
6021MPC826x processors), on others (parts of) the data cache can be
6022locked as (mis-) used as memory, etc.
6023
6024	Chris Hallinan posted a good summary of these issues to the
6025	U-Boot mailing list:
6026
6027	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6028	From: "Chris Hallinan" <clh@net1plus.com>
6029	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6030	...
6031
6032	Correct me if I'm wrong, folks, but the way I understand it
6033	is this: Using DCACHE as initial RAM for Stack, etc, does not
6034	require any physical RAM backing up the cache. The cleverness
6035	is that the cache is being used as a temporary supply of
6036	necessary storage before the SDRAM controller is setup. It's
6037	beyond the scope of this list to explain the details, but you
6038	can see how this works by studying the cache architecture and
6039	operation in the architecture and processor-specific manuals.
6040
6041	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6042	is another option for the system designer to use as an
6043	initial stack/RAM area prior to SDRAM being available. Either
6044	option should work for you. Using CS 4 should be fine if your
6045	board designers haven't used it for something that would
6046	cause you grief during the initial boot! It is frequently not
6047	used.
6048
6049	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6050	with your processor/board/system design. The default value
6051	you will find in any recent u-boot distribution in
6052	walnut.h should work for you. I'd set it to a value larger
6053	than your SDRAM module. If you have a 64MB SDRAM module, set
6054	it above 400_0000. Just make sure your board has no resources
6055	that are supposed to respond to that address! That code in
6056	start.S has been around a while and should work as is when
6057	you get the config right.
6058
6059	-Chris Hallinan
6060	DS4.COM, Inc.
6061
6062It is essential to remember this, since it has some impact on the C
6063code for the initialization procedures:
6064
6065* Initialized global data (data segment) is read-only. Do not attempt
6066  to write it.
6067
6068* Do not use any uninitialized global data (or implicitly initialized
6069  as zero data - BSS segment) at all - this is undefined, initiali-
6070  zation is performed later (when relocating to RAM).
6071
6072* Stack space is very limited. Avoid big data buffers or things like
6073  that.
6074
6075Having only the stack as writable memory limits means we cannot use
6076normal global data to share information between the code. But it
6077turned out that the implementation of U-Boot can be greatly
6078simplified by making a global data structure (gd_t) available to all
6079functions. We could pass a pointer to this data as argument to _all_
6080functions, but this would bloat the code. Instead we use a feature of
6081the GCC compiler (Global Register Variables) to share the data: we
6082place a pointer (gd) to the global data into a register which we
6083reserve for this purpose.
6084
6085When choosing a register for such a purpose we are restricted by the
6086relevant  (E)ABI  specifications for the current architecture, and by
6087GCC's implementation.
6088
6089For PowerPC, the following registers have specific use:
6090	R1:	stack pointer
6091	R2:	reserved for system use
6092	R3-R4:	parameter passing and return values
6093	R5-R10: parameter passing
6094	R13:	small data area pointer
6095	R30:	GOT pointer
6096	R31:	frame pointer
6097
6098	(U-Boot also uses R12 as internal GOT pointer. r12
6099	is a volatile register so r12 needs to be reset when
6100	going back and forth between asm and C)
6101
6102    ==> U-Boot will use R2 to hold a pointer to the global data
6103
6104    Note: on PPC, we could use a static initializer (since the
6105    address of the global data structure is known at compile time),
6106    but it turned out that reserving a register results in somewhat
6107    smaller code - although the code savings are not that big (on
6108    average for all boards 752 bytes for the whole U-Boot image,
6109    624 text + 127 data).
6110
6111On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6112	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6113
6114    ==> U-Boot will use P3 to hold a pointer to the global data
6115
6116On ARM, the following registers are used:
6117
6118	R0:	function argument word/integer result
6119	R1-R3:	function argument word
6120	R9:	platform specific
6121	R10:	stack limit (used only if stack checking is enabled)
6122	R11:	argument (frame) pointer
6123	R12:	temporary workspace
6124	R13:	stack pointer
6125	R14:	link register
6126	R15:	program counter
6127
6128    ==> U-Boot will use R9 to hold a pointer to the global data
6129
6130    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6131
6132On Nios II, the ABI is documented here:
6133	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6134
6135    ==> U-Boot will use gp to hold a pointer to the global data
6136
6137    Note: on Nios II, we give "-G0" option to gcc and don't use gp
6138    to access small data sections, so gp is free.
6139
6140On NDS32, the following registers are used:
6141
6142	R0-R1:	argument/return
6143	R2-R5:	argument
6144	R15:	temporary register for assembler
6145	R16:	trampoline register
6146	R28:	frame pointer (FP)
6147	R29:	global pointer (GP)
6148	R30:	link register (LP)
6149	R31:	stack pointer (SP)
6150	PC:	program counter (PC)
6151
6152    ==> U-Boot will use R10 to hold a pointer to the global data
6153
6154NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6155or current versions of GCC may "optimize" the code too much.
6156
6157Memory Management:
6158------------------
6159
6160U-Boot runs in system state and uses physical addresses, i.e. the
6161MMU is not used either for address mapping nor for memory protection.
6162
6163The available memory is mapped to fixed addresses using the memory
6164controller. In this process, a contiguous block is formed for each
6165memory type (Flash, SDRAM, SRAM), even when it consists of several
6166physical memory banks.
6167
6168U-Boot is installed in the first 128 kB of the first Flash bank (on
6169TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6170booting and sizing and initializing DRAM, the code relocates itself
6171to the upper end of DRAM. Immediately below the U-Boot code some
6172memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6173configuration setting]. Below that, a structure with global Board
6174Info data is placed, followed by the stack (growing downward).
6175
6176Additionally, some exception handler code is copied to the low 8 kB
6177of DRAM (0x00000000 ... 0x00001FFF).
6178
6179So a typical memory configuration with 16 MB of DRAM could look like
6180this:
6181
6182	0x0000 0000	Exception Vector code
6183	      :
6184	0x0000 1FFF
6185	0x0000 2000	Free for Application Use
6186	      :
6187	      :
6188
6189	      :
6190	      :
6191	0x00FB FF20	Monitor Stack (Growing downward)
6192	0x00FB FFAC	Board Info Data and permanent copy of global data
6193	0x00FC 0000	Malloc Arena
6194	      :
6195	0x00FD FFFF
6196	0x00FE 0000	RAM Copy of Monitor Code
6197	...		eventually: LCD or video framebuffer
6198	...		eventually: pRAM (Protected RAM - unchanged by reset)
6199	0x00FF FFFF	[End of RAM]
6200
6201
6202System Initialization:
6203----------------------
6204
6205In the reset configuration, U-Boot starts at the reset entry point
6206(on most PowerPC systems at address 0x00000100). Because of the reset
6207configuration for CS0# this is a mirror of the on board Flash memory.
6208To be able to re-map memory U-Boot then jumps to its link address.
6209To be able to implement the initialization code in C, a (small!)
6210initial stack is set up in the internal Dual Ported RAM (in case CPUs
6211which provide such a feature like MPC8xx or MPC8260), or in a locked
6212part of the data cache. After that, U-Boot initializes the CPU core,
6213the caches and the SIU.
6214
6215Next, all (potentially) available memory banks are mapped using a
6216preliminary mapping. For example, we put them on 512 MB boundaries
6217(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6218on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6219programmed for SDRAM access. Using the temporary configuration, a
6220simple memory test is run that determines the size of the SDRAM
6221banks.
6222
6223When there is more than one SDRAM bank, and the banks are of
6224different size, the largest is mapped first. For equal size, the first
6225bank (CS2#) is mapped first. The first mapping is always for address
62260x00000000, with any additional banks following immediately to create
6227contiguous memory starting from 0.
6228
6229Then, the monitor installs itself at the upper end of the SDRAM area
6230and allocates memory for use by malloc() and for the global Board
6231Info data; also, the exception vector code is copied to the low RAM
6232pages, and the final stack is set up.
6233
6234Only after this relocation will you have a "normal" C environment;
6235until that you are restricted in several ways, mostly because you are
6236running from ROM, and because the code will have to be relocated to a
6237new address in RAM.
6238
6239
6240U-Boot Porting Guide:
6241----------------------
6242
6243[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6244list, October 2002]
6245
6246
6247int main(int argc, char *argv[])
6248{
6249	sighandler_t no_more_time;
6250
6251	signal(SIGALRM, no_more_time);
6252	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6253
6254	if (available_money > available_manpower) {
6255		Pay consultant to port U-Boot;
6256		return 0;
6257	}
6258
6259	Download latest U-Boot source;
6260
6261	Subscribe to u-boot mailing list;
6262
6263	if (clueless)
6264		email("Hi, I am new to U-Boot, how do I get started?");
6265
6266	while (learning) {
6267		Read the README file in the top level directory;
6268		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6269		Read applicable doc/*.README;
6270		Read the source, Luke;
6271		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6272	}
6273
6274	if (available_money > toLocalCurrency ($2500))
6275		Buy a BDI3000;
6276	else
6277		Add a lot of aggravation and time;
6278
6279	if (a similar board exists) {	/* hopefully... */
6280		cp -a board/<similar> board/<myboard>
6281		cp include/configs/<similar>.h include/configs/<myboard>.h
6282	} else {
6283		Create your own board support subdirectory;
6284		Create your own board include/configs/<myboard>.h file;
6285	}
6286	Edit new board/<myboard> files
6287	Edit new include/configs/<myboard>.h
6288
6289	while (!accepted) {
6290		while (!running) {
6291			do {
6292				Add / modify source code;
6293			} until (compiles);
6294			Debug;
6295			if (clueless)
6296				email("Hi, I am having problems...");
6297		}
6298		Send patch file to the U-Boot email list;
6299		if (reasonable critiques)
6300			Incorporate improvements from email list code review;
6301		else
6302			Defend code as written;
6303	}
6304
6305	return 0;
6306}
6307
6308void no_more_time (int sig)
6309{
6310      hire_a_guru();
6311}
6312
6313
6314Coding Standards:
6315-----------------
6316
6317All contributions to U-Boot should conform to the Linux kernel
6318coding style; see the file "Documentation/CodingStyle" and the script
6319"scripts/Lindent" in your Linux kernel source directory.
6320
6321Source files originating from a different project (for example the
6322MTD subsystem) are generally exempt from these guidelines and are not
6323reformatted to ease subsequent migration to newer versions of those
6324sources.
6325
6326Please note that U-Boot is implemented in C (and to some small parts in
6327Assembler); no C++ is used, so please do not use C++ style comments (//)
6328in your code.
6329
6330Please also stick to the following formatting rules:
6331- remove any trailing white space
6332- use TAB characters for indentation and vertical alignment, not spaces
6333- make sure NOT to use DOS '\r\n' line feeds
6334- do not add more than 2 consecutive empty lines to source files
6335- do not add trailing empty lines to source files
6336
6337Submissions which do not conform to the standards may be returned
6338with a request to reformat the changes.
6339
6340
6341Submitting Patches:
6342-------------------
6343
6344Since the number of patches for U-Boot is growing, we need to
6345establish some rules. Submissions which do not conform to these rules
6346may be rejected, even when they contain important and valuable stuff.
6347
6348Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6349
6350Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6351see http://lists.denx.de/mailman/listinfo/u-boot
6352
6353When you send a patch, please include the following information with
6354it:
6355
6356* For bug fixes: a description of the bug and how your patch fixes
6357  this bug. Please try to include a way of demonstrating that the
6358  patch actually fixes something.
6359
6360* For new features: a description of the feature and your
6361  implementation.
6362
6363* A CHANGELOG entry as plaintext (separate from the patch)
6364
6365* For major contributions, add a MAINTAINERS file with your
6366  information and associated file and directory references.
6367
6368* When you add support for a new board, don't forget to add a
6369  maintainer e-mail address to the boards.cfg file, too.
6370
6371* If your patch adds new configuration options, don't forget to
6372  document these in the README file.
6373
6374* The patch itself. If you are using git (which is *strongly*
6375  recommended) you can easily generate the patch using the
6376  "git format-patch". If you then use "git send-email" to send it to
6377  the U-Boot mailing list, you will avoid most of the common problems
6378  with some other mail clients.
6379
6380  If you cannot use git, use "diff -purN OLD NEW". If your version of
6381  diff does not support these options, then get the latest version of
6382  GNU diff.
6383
6384  The current directory when running this command shall be the parent
6385  directory of the U-Boot source tree (i. e. please make sure that
6386  your patch includes sufficient directory information for the
6387  affected files).
6388
6389  We prefer patches as plain text. MIME attachments are discouraged,
6390  and compressed attachments must not be used.
6391
6392* If one logical set of modifications affects or creates several
6393  files, all these changes shall be submitted in a SINGLE patch file.
6394
6395* Changesets that contain different, unrelated modifications shall be
6396  submitted as SEPARATE patches, one patch per changeset.
6397
6398
6399Notes:
6400
6401* Before sending the patch, run the buildman script on your patched
6402  source tree and make sure that no errors or warnings are reported
6403  for any of the boards.
6404
6405* Keep your modifications to the necessary minimum: A patch
6406  containing several unrelated changes or arbitrary reformats will be
6407  returned with a request to re-formatting / split it.
6408
6409* If you modify existing code, make sure that your new code does not
6410  add to the memory footprint of the code ;-) Small is beautiful!
6411  When adding new features, these should compile conditionally only
6412  (using #ifdef), and the resulting code with the new feature
6413  disabled must not need more memory than the old code without your
6414  modification.
6415
6416* Remember that there is a size limit of 100 kB per message on the
6417  u-boot mailing list. Bigger patches will be moderated. If they are
6418  reasonable and not too big, they will be acknowledged. But patches
6419  bigger than the size limit should be avoided.
6420