xref: /rk3399_rockchip-uboot/README (revision 8f925584145efecd9a6323801689cffd69cf0b09)
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- Autoboot Command:
836		CONFIG_BOOTCOMMAND
837		Only needed when CONFIG_BOOTDELAY is enabled;
838		define a command string that is automatically executed
839		when no character is read on the console interface
840		within "Boot Delay" after reset.
841
842		CONFIG_BOOTARGS
843		This can be used to pass arguments to the bootm
844		command. The value of CONFIG_BOOTARGS goes into the
845		environment value "bootargs".
846
847		CONFIG_RAMBOOT and CONFIG_NFSBOOT
848		The value of these goes into the environment as
849		"ramboot" and "nfsboot" respectively, and can be used
850		as a convenience, when switching between booting from
851		RAM and NFS.
852
853- Bootcount:
854		CONFIG_BOOTCOUNT_LIMIT
855		Implements a mechanism for detecting a repeating reboot
856		cycle, see:
857		http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
858
859		CONFIG_BOOTCOUNT_ENV
860		If no softreset save registers are found on the hardware
861		"bootcount" is stored in the environment. To prevent a
862		saveenv on all reboots, the environment variable
863		"upgrade_available" is used. If "upgrade_available" is
864		0, "bootcount" is always 0, if "upgrade_available" is
865		1 "bootcount" is incremented in the environment.
866		So the Userspace Applikation must set the "upgrade_available"
867		and "bootcount" variable to 0, if a boot was successfully.
868
869- Pre-Boot Commands:
870		CONFIG_PREBOOT
871
872		When this option is #defined, the existence of the
873		environment variable "preboot" will be checked
874		immediately before starting the CONFIG_BOOTDELAY
875		countdown and/or running the auto-boot command resp.
876		entering interactive mode.
877
878		This feature is especially useful when "preboot" is
879		automatically generated or modified. For an example
880		see the LWMON board specific code: here "preboot" is
881		modified when the user holds down a certain
882		combination of keys on the (special) keyboard when
883		booting the systems
884
885- Serial Download Echo Mode:
886		CONFIG_LOADS_ECHO
887		If defined to 1, all characters received during a
888		serial download (using the "loads" command) are
889		echoed back. This might be needed by some terminal
890		emulations (like "cu"), but may as well just take
891		time on others. This setting #define's the initial
892		value of the "loads_echo" environment variable.
893
894- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
895		CONFIG_KGDB_BAUDRATE
896		Select one of the baudrates listed in
897		CONFIG_SYS_BAUDRATE_TABLE, see below.
898
899- Monitor Functions:
900		Monitor commands can be included or excluded
901		from the build by using the #include files
902		<config_cmd_all.h> and #undef'ing unwanted
903		commands, or adding #define's for wanted commands.
904
905		The default command configuration includes all commands
906		except those marked below with a "*".
907
908		CONFIG_CMD_AES		  AES 128 CBC encrypt/decrypt
909		CONFIG_CMD_ASKENV	* ask for env variable
910		CONFIG_CMD_BDI		  bdinfo
911		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
912		CONFIG_CMD_BMP		* BMP support
913		CONFIG_CMD_BSP		* Board specific commands
914		CONFIG_CMD_BOOTD	  bootd
915		CONFIG_CMD_BOOTI	* ARM64 Linux kernel Image support
916		CONFIG_CMD_CACHE	* icache, dcache
917		CONFIG_CMD_CLK   	* clock command support
918		CONFIG_CMD_CONSOLE	  coninfo
919		CONFIG_CMD_CRC32	* crc32
920		CONFIG_CMD_DATE		* support for RTC, date/time...
921		CONFIG_CMD_DHCP		* DHCP support
922		CONFIG_CMD_DIAG		* Diagnostics
923		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
924		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
925		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
926		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
927		CONFIG_CMD_DTT		* Digital Therm and Thermostat
928		CONFIG_CMD_ECHO		  echo arguments
929		CONFIG_CMD_EDITENV	  edit env variable
930		CONFIG_CMD_EEPROM	* EEPROM read/write support
931		CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands
932		CONFIG_CMD_ELF		* bootelf, bootvx
933		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
934		CONFIG_CMD_ENV_FLAGS	* display details about env flags
935		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
936		CONFIG_CMD_EXPORTENV	* export the environment
937		CONFIG_CMD_EXT2		* ext2 command support
938		CONFIG_CMD_EXT4		* ext4 command support
939		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
940					  that work for multiple fs types
941		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
942		CONFIG_CMD_SAVEENV	  saveenv
943		CONFIG_CMD_FDC		* Floppy Disk Support
944		CONFIG_CMD_FAT		* FAT command support
945		CONFIG_CMD_FLASH	  flinfo, erase, protect
946		CONFIG_CMD_FPGA		  FPGA device initialization support
947		CONFIG_CMD_FUSE		* Device fuse support
948		CONFIG_CMD_GETTIME	* Get time since boot
949		CONFIG_CMD_GO		* the 'go' command (exec code)
950		CONFIG_CMD_GREPENV	* search environment
951		CONFIG_CMD_HASH		* calculate hash / digest
952		CONFIG_CMD_I2C		* I2C serial bus support
953		CONFIG_CMD_IDE		* IDE harddisk support
954		CONFIG_CMD_IMI		  iminfo
955		CONFIG_CMD_IMLS		  List all images found in NOR flash
956		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
957		CONFIG_CMD_IMMAP	* IMMR dump support
958		CONFIG_CMD_IOTRACE	* I/O tracing for debugging
959		CONFIG_CMD_IMPORTENV	* import an environment
960		CONFIG_CMD_INI		* import data from an ini file into the env
961		CONFIG_CMD_IRQ		* irqinfo
962		CONFIG_CMD_ITEST	  Integer/string test of 2 values
963		CONFIG_CMD_JFFS2	* JFFS2 Support
964		CONFIG_CMD_KGDB		* kgdb
965		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
966		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
967					  (169.254.*.*)
968		CONFIG_CMD_LOADB	  loadb
969		CONFIG_CMD_LOADS	  loads
970		CONFIG_CMD_MD5SUM	* print md5 message digest
971					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
972		CONFIG_CMD_MEMINFO	* Display detailed memory information
973		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
974					  loop, loopw
975		CONFIG_CMD_MEMTEST	* mtest
976		CONFIG_CMD_MISC		  Misc functions like sleep etc
977		CONFIG_CMD_MMC		* MMC memory mapped support
978		CONFIG_CMD_MII		* MII utility commands
979		CONFIG_CMD_MTDPARTS	* MTD partition support
980		CONFIG_CMD_NAND		* NAND support
981		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
982		CONFIG_CMD_NFS		  NFS support
983		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
984		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
985		CONFIG_CMD_PCI		* pciinfo
986		CONFIG_CMD_PCMCIA		* PCMCIA support
987		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
988					  host
989		CONFIG_CMD_PORTIO	* Port I/O
990		CONFIG_CMD_READ		* Read raw data from partition
991		CONFIG_CMD_REGINFO	* Register dump
992		CONFIG_CMD_RUN		  run command in env variable
993		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
994		CONFIG_CMD_SAVES	* save S record dump
995		CONFIG_SCSI		* SCSI Support
996		CONFIG_CMD_SDRAM	* print SDRAM configuration information
997					  (requires CONFIG_CMD_I2C)
998		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
999					  (4xx only)
1000		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
1001		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
1002					  (requires CONFIG_CMD_MEMORY)
1003		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
1004		CONFIG_CMD_SOURCE	  "source" command Support
1005		CONFIG_CMD_SPI		* SPI serial bus support
1006		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
1007		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
1008		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
1009		CONFIG_CMD_TIMER	* access to the system tick timer
1010		CONFIG_CMD_USB		* USB support
1011		CONFIG_CMD_CDP		* Cisco Discover Protocol support
1012		CONFIG_CMD_MFSL		* Microblaze FSL support
1013		CONFIG_CMD_XIMG		  Load part of Multi Image
1014		CONFIG_CMD_UUID		* Generate random UUID or GUID string
1015
1016		EXAMPLE: If you want all functions except of network
1017		support you can write:
1018
1019		#include "config_cmd_all.h"
1020		#undef CONFIG_CMD_NET
1021
1022	Other Commands:
1023		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
1024
1025	Note:	Don't enable the "icache" and "dcache" commands
1026		(configuration option CONFIG_CMD_CACHE) unless you know
1027		what you (and your U-Boot users) are doing. Data
1028		cache cannot be enabled on systems like the 8xx or
1029		8260 (where accesses to the IMMR region must be
1030		uncached), and it cannot be disabled on all other
1031		systems where we (mis-) use the data cache to hold an
1032		initial stack and some data.
1033
1034
1035		XXX - this list needs to get updated!
1036
1037- Removal of commands
1038		If no commands are needed to boot, you can disable
1039		CONFIG_CMDLINE to remove them. In this case, the command line
1040		will not be available, and when U-Boot wants to execute the
1041		boot command (on start-up) it will call board_run_command()
1042		instead. This can reduce image size significantly for very
1043		simple boot procedures.
1044
1045- Regular expression support:
1046		CONFIG_REGEX
1047		If this variable is defined, U-Boot is linked against
1048		the SLRE (Super Light Regular Expression) library,
1049		which adds regex support to some commands, as for
1050		example "env grep" and "setexpr".
1051
1052- Device tree:
1053		CONFIG_OF_CONTROL
1054		If this variable is defined, U-Boot will use a device tree
1055		to configure its devices, instead of relying on statically
1056		compiled #defines in the board file. This option is
1057		experimental and only available on a few boards. The device
1058		tree is available in the global data as gd->fdt_blob.
1059
1060		U-Boot needs to get its device tree from somewhere. This can
1061		be done using one of the two options below:
1062
1063		CONFIG_OF_EMBED
1064		If this variable is defined, U-Boot will embed a device tree
1065		binary in its image. This device tree file should be in the
1066		board directory and called <soc>-<board>.dts. The binary file
1067		is then picked up in board_init_f() and made available through
1068		the global data structure as gd->blob.
1069
1070		CONFIG_OF_SEPARATE
1071		If this variable is defined, U-Boot will build a device tree
1072		binary. It will be called u-boot.dtb. Architecture-specific
1073		code will locate it at run-time. Generally this works by:
1074
1075			cat u-boot.bin u-boot.dtb >image.bin
1076
1077		and in fact, U-Boot does this for you, creating a file called
1078		u-boot-dtb.bin which is useful in the common case. You can
1079		still use the individual files if you need something more
1080		exotic.
1081
1082- Watchdog:
1083		CONFIG_WATCHDOG
1084		If this variable is defined, it enables watchdog
1085		support for the SoC. There must be support in the SoC
1086		specific code for a watchdog. For the 8xx and 8260
1087		CPUs, the SIU Watchdog feature is enabled in the SYPCR
1088		register.  When supported for a specific SoC is
1089		available, then no further board specific code should
1090		be needed to use it.
1091
1092		CONFIG_HW_WATCHDOG
1093		When using a watchdog circuitry external to the used
1094		SoC, then define this variable and provide board
1095		specific code for the "hw_watchdog_reset" function.
1096
1097		CONFIG_AT91_HW_WDT_TIMEOUT
1098		specify the timeout in seconds. default 2 seconds.
1099
1100- U-Boot Version:
1101		CONFIG_VERSION_VARIABLE
1102		If this variable is defined, an environment variable
1103		named "ver" is created by U-Boot showing the U-Boot
1104		version as printed by the "version" command.
1105		Any change to this variable will be reverted at the
1106		next reset.
1107
1108- Real-Time Clock:
1109
1110		When CONFIG_CMD_DATE is selected, the type of the RTC
1111		has to be selected, too. Define exactly one of the
1112		following options:
1113
1114		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1115		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1116		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1117		CONFIG_RTC_MC146818	- use MC146818 RTC
1118		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1119		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1120		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1121		CONFIG_RTC_DS1339	- use Maxim, Inc. DS1339 RTC
1122		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1123		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1124		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1125		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1126		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1127					  RV3029 RTC.
1128
1129		Note that if the RTC uses I2C, then the I2C interface
1130		must also be configured. See I2C Support, below.
1131
1132- GPIO Support:
1133		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1134
1135		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1136		chip-ngpio pairs that tell the PCA953X driver the number of
1137		pins supported by a particular chip.
1138
1139		Note that if the GPIO device uses I2C, then the I2C interface
1140		must also be configured. See I2C Support, below.
1141
1142- I/O tracing:
1143		When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
1144		accesses and can checksum them or write a list of them out
1145		to memory. See the 'iotrace' command for details. This is
1146		useful for testing device drivers since it can confirm that
1147		the driver behaves the same way before and after a code
1148		change. Currently this is supported on sandbox and arm. To
1149		add support for your architecture, add '#include <iotrace.h>'
1150		to the bottom of arch/<arch>/include/asm/io.h and test.
1151
1152		Example output from the 'iotrace stats' command is below.
1153		Note that if the trace buffer is exhausted, the checksum will
1154		still continue to operate.
1155
1156			iotrace is enabled
1157			Start:  10000000	(buffer start address)
1158			Size:   00010000	(buffer size)
1159			Offset: 00000120	(current buffer offset)
1160			Output: 10000120	(start + offset)
1161			Count:  00000018	(number of trace records)
1162			CRC32:  9526fb66	(CRC32 of all trace records)
1163
1164- Timestamp Support:
1165
1166		When CONFIG_TIMESTAMP is selected, the timestamp
1167		(date and time) of an image is printed by image
1168		commands like bootm or iminfo. This option is
1169		automatically enabled when you select CONFIG_CMD_DATE .
1170
1171- Partition Labels (disklabels) Supported:
1172		Zero or more of the following:
1173		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1174		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1175				       Intel architecture, USB sticks, etc.
1176		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1177		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1178				       bootloader.  Note 2TB partition limit; see
1179				       disk/part_efi.c
1180		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1181
1182		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1183		CONFIG_SCSI) you must configure support for at
1184		least one non-MTD partition type as well.
1185
1186- IDE Reset method:
1187		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1188		board configurations files but used nowhere!
1189
1190		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1191		be performed by calling the function
1192			ide_set_reset(int reset)
1193		which has to be defined in a board specific file
1194
1195- ATAPI Support:
1196		CONFIG_ATAPI
1197
1198		Set this to enable ATAPI support.
1199
1200- LBA48 Support
1201		CONFIG_LBA48
1202
1203		Set this to enable support for disks larger than 137GB
1204		Also look at CONFIG_SYS_64BIT_LBA.
1205		Whithout these , LBA48 support uses 32bit variables and will 'only'
1206		support disks up to 2.1TB.
1207
1208		CONFIG_SYS_64BIT_LBA:
1209			When enabled, makes the IDE subsystem use 64bit sector addresses.
1210			Default is 32bit.
1211
1212- SCSI Support:
1213		At the moment only there is only support for the
1214		SYM53C8XX SCSI controller; define
1215		CONFIG_SCSI_SYM53C8XX to enable it.
1216
1217		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1218		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1219		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1220		maximum numbers of LUNs, SCSI ID's and target
1221		devices.
1222		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1223
1224		The environment variable 'scsidevs' is set to the number of
1225		SCSI devices found during the last scan.
1226
1227- NETWORK Support (PCI):
1228		CONFIG_E1000
1229		Support for Intel 8254x/8257x gigabit chips.
1230
1231		CONFIG_E1000_SPI
1232		Utility code for direct access to the SPI bus on Intel 8257x.
1233		This does not do anything useful unless you set at least one
1234		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1235
1236		CONFIG_E1000_SPI_GENERIC
1237		Allow generic access to the SPI bus on the Intel 8257x, for
1238		example with the "sspi" command.
1239
1240		CONFIG_CMD_E1000
1241		Management command for E1000 devices.  When used on devices
1242		with SPI support you can reprogram the EEPROM from U-Boot.
1243
1244		CONFIG_EEPRO100
1245		Support for Intel 82557/82559/82559ER chips.
1246		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1247		write routine for first time initialisation.
1248
1249		CONFIG_TULIP
1250		Support for Digital 2114x chips.
1251		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1252		modem chip initialisation (KS8761/QS6611).
1253
1254		CONFIG_NATSEMI
1255		Support for National dp83815 chips.
1256
1257		CONFIG_NS8382X
1258		Support for National dp8382[01] gigabit chips.
1259
1260- NETWORK Support (other):
1261
1262		CONFIG_DRIVER_AT91EMAC
1263		Support for AT91RM9200 EMAC.
1264
1265			CONFIG_RMII
1266			Define this to use reduced MII inteface
1267
1268			CONFIG_DRIVER_AT91EMAC_QUIET
1269			If this defined, the driver is quiet.
1270			The driver doen't show link status messages.
1271
1272		CONFIG_CALXEDA_XGMAC
1273		Support for the Calxeda XGMAC device
1274
1275		CONFIG_LAN91C96
1276		Support for SMSC's LAN91C96 chips.
1277
1278			CONFIG_LAN91C96_USE_32_BIT
1279			Define this to enable 32 bit addressing
1280
1281		CONFIG_SMC91111
1282		Support for SMSC's LAN91C111 chip
1283
1284			CONFIG_SMC91111_BASE
1285			Define this to hold the physical address
1286			of the device (I/O space)
1287
1288			CONFIG_SMC_USE_32_BIT
1289			Define this if data bus is 32 bits
1290
1291			CONFIG_SMC_USE_IOFUNCS
1292			Define this to use i/o functions instead of macros
1293			(some hardware wont work with macros)
1294
1295		CONFIG_DRIVER_TI_EMAC
1296		Support for davinci emac
1297
1298			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1299			Define this if you have more then 3 PHYs.
1300
1301		CONFIG_FTGMAC100
1302		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1303
1304			CONFIG_FTGMAC100_EGIGA
1305			Define this to use GE link update with gigabit PHY.
1306			Define this if FTGMAC100 is connected to gigabit PHY.
1307			If your system has 10/100 PHY only, it might not occur
1308			wrong behavior. Because PHY usually return timeout or
1309			useless data when polling gigabit status and gigabit
1310			control registers. This behavior won't affect the
1311			correctnessof 10/100 link speed update.
1312
1313		CONFIG_SMC911X
1314		Support for SMSC's LAN911x and LAN921x chips
1315
1316			CONFIG_SMC911X_BASE
1317			Define this to hold the physical address
1318			of the device (I/O space)
1319
1320			CONFIG_SMC911X_32_BIT
1321			Define this if data bus is 32 bits
1322
1323			CONFIG_SMC911X_16_BIT
1324			Define this if data bus is 16 bits. If your processor
1325			automatically converts one 32 bit word to two 16 bit
1326			words you may also try CONFIG_SMC911X_32_BIT.
1327
1328		CONFIG_SH_ETHER
1329		Support for Renesas on-chip Ethernet controller
1330
1331			CONFIG_SH_ETHER_USE_PORT
1332			Define the number of ports to be used
1333
1334			CONFIG_SH_ETHER_PHY_ADDR
1335			Define the ETH PHY's address
1336
1337			CONFIG_SH_ETHER_CACHE_WRITEBACK
1338			If this option is set, the driver enables cache flush.
1339
1340- PWM Support:
1341		CONFIG_PWM_IMX
1342		Support for PWM module on the imx6.
1343
1344- TPM Support:
1345		CONFIG_TPM
1346		Support TPM devices.
1347
1348		CONFIG_TPM_TIS_INFINEON
1349		Support for Infineon i2c bus TPM devices. Only one device
1350		per system is supported at this time.
1351
1352			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1353			Define the burst count bytes upper limit
1354
1355		CONFIG_TPM_ST33ZP24
1356		Support for STMicroelectronics TPM devices. Requires DM_TPM support.
1357
1358			CONFIG_TPM_ST33ZP24_I2C
1359			Support for STMicroelectronics ST33ZP24 I2C devices.
1360			Requires TPM_ST33ZP24 and I2C.
1361
1362			CONFIG_TPM_ST33ZP24_SPI
1363			Support for STMicroelectronics ST33ZP24 SPI devices.
1364			Requires TPM_ST33ZP24 and SPI.
1365
1366		CONFIG_TPM_ATMEL_TWI
1367		Support for Atmel TWI TPM device. Requires I2C support.
1368
1369		CONFIG_TPM_TIS_LPC
1370		Support for generic parallel port TPM devices. Only one device
1371		per system is supported at this time.
1372
1373			CONFIG_TPM_TIS_BASE_ADDRESS
1374			Base address where the generic TPM device is mapped
1375			to. Contemporary x86 systems usually map it at
1376			0xfed40000.
1377
1378		CONFIG_CMD_TPM
1379		Add tpm monitor functions.
1380		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1381		provides monitor access to authorized functions.
1382
1383		CONFIG_TPM
1384		Define this to enable the TPM support library which provides
1385		functional interfaces to some TPM commands.
1386		Requires support for a TPM device.
1387
1388		CONFIG_TPM_AUTH_SESSIONS
1389		Define this to enable authorized functions in the TPM library.
1390		Requires CONFIG_TPM and CONFIG_SHA1.
1391
1392- USB Support:
1393		At the moment only the UHCI host controller is
1394		supported (PIP405, MIP405, MPC5200); define
1395		CONFIG_USB_UHCI to enable it.
1396		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1397		and define CONFIG_USB_STORAGE to enable the USB
1398		storage devices.
1399		Note:
1400		Supported are USB Keyboards and USB Floppy drives
1401		(TEAC FD-05PUB).
1402		MPC5200 USB requires additional defines:
1403			CONFIG_USB_CLOCK
1404				for 528 MHz Clock: 0x0001bbbb
1405			CONFIG_PSC3_USB
1406				for USB on PSC3
1407			CONFIG_USB_CONFIG
1408				for differential drivers: 0x00001000
1409				for single ended drivers: 0x00005000
1410				for differential drivers on PSC3: 0x00000100
1411				for single ended drivers on PSC3: 0x00004100
1412			CONFIG_SYS_USB_EVENT_POLL
1413				May be defined to allow interrupt polling
1414				instead of using asynchronous interrupts
1415
1416		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1417		txfilltuning field in the EHCI controller on reset.
1418
1419		CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
1420		HW module registers.
1421
1422- USB Device:
1423		Define the below if you wish to use the USB console.
1424		Once firmware is rebuilt from a serial console issue the
1425		command "setenv stdin usbtty; setenv stdout usbtty" and
1426		attach your USB cable. The Unix command "dmesg" should print
1427		it has found a new device. The environment variable usbtty
1428		can be set to gserial or cdc_acm to enable your device to
1429		appear to a USB host as a Linux gserial device or a
1430		Common Device Class Abstract Control Model serial device.
1431		If you select usbtty = gserial you should be able to enumerate
1432		a Linux host by
1433		# modprobe usbserial vendor=0xVendorID product=0xProductID
1434		else if using cdc_acm, simply setting the environment
1435		variable usbtty to be cdc_acm should suffice. The following
1436		might be defined in YourBoardName.h
1437
1438			CONFIG_USB_DEVICE
1439			Define this to build a UDC device
1440
1441			CONFIG_USB_TTY
1442			Define this to have a tty type of device available to
1443			talk to the UDC device
1444
1445			CONFIG_USBD_HS
1446			Define this to enable the high speed support for usb
1447			device and usbtty. If this feature is enabled, a routine
1448			int is_usbd_high_speed(void)
1449			also needs to be defined by the driver to dynamically poll
1450			whether the enumeration has succeded at high speed or full
1451			speed.
1452
1453			CONFIG_SYS_CONSOLE_IS_IN_ENV
1454			Define this if you want stdin, stdout &/or stderr to
1455			be set to usbtty.
1456
1457			mpc8xx:
1458				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1459				Derive USB clock from external clock "blah"
1460				- CONFIG_SYS_USB_EXTC_CLK 0x02
1461
1462		If you have a USB-IF assigned VendorID then you may wish to
1463		define your own vendor specific values either in BoardName.h
1464		or directly in usbd_vendor_info.h. If you don't define
1465		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1466		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1467		should pretend to be a Linux device to it's target host.
1468
1469			CONFIG_USBD_MANUFACTURER
1470			Define this string as the name of your company for
1471			- CONFIG_USBD_MANUFACTURER "my company"
1472
1473			CONFIG_USBD_PRODUCT_NAME
1474			Define this string as the name of your product
1475			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1476
1477			CONFIG_USBD_VENDORID
1478			Define this as your assigned Vendor ID from the USB
1479			Implementors Forum. This *must* be a genuine Vendor ID
1480			to avoid polluting the USB namespace.
1481			- CONFIG_USBD_VENDORID 0xFFFF
1482
1483			CONFIG_USBD_PRODUCTID
1484			Define this as the unique Product ID
1485			for your device
1486			- CONFIG_USBD_PRODUCTID 0xFFFF
1487
1488- ULPI Layer Support:
1489		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1490		the generic ULPI layer. The generic layer accesses the ULPI PHY
1491		via the platform viewport, so you need both the genric layer and
1492		the viewport enabled. Currently only Chipidea/ARC based
1493		viewport is supported.
1494		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1495		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1496		If your ULPI phy needs a different reference clock than the
1497		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1498		the appropriate value in Hz.
1499
1500- MMC Support:
1501		The MMC controller on the Intel PXA is supported. To
1502		enable this define CONFIG_MMC. The MMC can be
1503		accessed from the boot prompt by mapping the device
1504		to physical memory similar to flash. Command line is
1505		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1506		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1507
1508		CONFIG_SH_MMCIF
1509		Support for Renesas on-chip MMCIF controller
1510
1511			CONFIG_SH_MMCIF_ADDR
1512			Define the base address of MMCIF registers
1513
1514			CONFIG_SH_MMCIF_CLK
1515			Define the clock frequency for MMCIF
1516
1517		CONFIG_GENERIC_MMC
1518		Enable the generic MMC driver
1519
1520		CONFIG_SUPPORT_EMMC_BOOT
1521		Enable some additional features of the eMMC boot partitions.
1522
1523		CONFIG_SUPPORT_EMMC_RPMB
1524		Enable the commands for reading, writing and programming the
1525		key for the Replay Protection Memory Block partition in eMMC.
1526
1527- USB Device Firmware Update (DFU) class support:
1528		CONFIG_USB_FUNCTION_DFU
1529		This enables the USB portion of the DFU USB class
1530
1531		CONFIG_CMD_DFU
1532		This enables the command "dfu" which is used to have
1533		U-Boot create a DFU class device via USB.  This command
1534		requires that the "dfu_alt_info" environment variable be
1535		set and define the alt settings to expose to the host.
1536
1537		CONFIG_DFU_MMC
1538		This enables support for exposing (e)MMC devices via DFU.
1539
1540		CONFIG_DFU_NAND
1541		This enables support for exposing NAND devices via DFU.
1542
1543		CONFIG_DFU_RAM
1544		This enables support for exposing RAM via DFU.
1545		Note: DFU spec refer to non-volatile memory usage, but
1546		allow usages beyond the scope of spec - here RAM usage,
1547		one that would help mostly the developer.
1548
1549		CONFIG_SYS_DFU_DATA_BUF_SIZE
1550		Dfu transfer uses a buffer before writing data to the
1551		raw storage device. Make the size (in bytes) of this buffer
1552		configurable. The size of this buffer is also configurable
1553		through the "dfu_bufsiz" environment variable.
1554
1555		CONFIG_SYS_DFU_MAX_FILE_SIZE
1556		When updating files rather than the raw storage device,
1557		we use a static buffer to copy the file into and then write
1558		the buffer once we've been given the whole file.  Define
1559		this to the maximum filesize (in bytes) for the buffer.
1560		Default is 4 MiB if undefined.
1561
1562		DFU_DEFAULT_POLL_TIMEOUT
1563		Poll timeout [ms], is the timeout a device can send to the
1564		host. The host must wait for this timeout before sending
1565		a subsequent DFU_GET_STATUS request to the device.
1566
1567		DFU_MANIFEST_POLL_TIMEOUT
1568		Poll timeout [ms], which the device sends to the host when
1569		entering dfuMANIFEST state. Host waits this timeout, before
1570		sending again an USB request to the device.
1571
1572- USB Device Android Fastboot support:
1573		CONFIG_USB_FUNCTION_FASTBOOT
1574		This enables the USB part of the fastboot gadget
1575
1576		CONFIG_CMD_FASTBOOT
1577		This enables the command "fastboot" which enables the Android
1578		fastboot mode for the platform's USB device. Fastboot is a USB
1579		protocol for downloading images, flashing and device control
1580		used on Android devices.
1581		See doc/README.android-fastboot for more information.
1582
1583		CONFIG_ANDROID_BOOT_IMAGE
1584		This enables support for booting images which use the Android
1585		image format header.
1586
1587		CONFIG_FASTBOOT_BUF_ADDR
1588		The fastboot protocol requires a large memory buffer for
1589		downloads. Define this to the starting RAM address to use for
1590		downloaded images.
1591
1592		CONFIG_FASTBOOT_BUF_SIZE
1593		The fastboot protocol requires a large memory buffer for
1594		downloads. This buffer should be as large as possible for a
1595		platform. Define this to the size available RAM for fastboot.
1596
1597		CONFIG_FASTBOOT_FLASH
1598		The fastboot protocol includes a "flash" command for writing
1599		the downloaded image to a non-volatile storage device. Define
1600		this to enable the "fastboot flash" command.
1601
1602		CONFIG_FASTBOOT_FLASH_MMC_DEV
1603		The fastboot "flash" command requires additional information
1604		regarding the non-volatile storage device. Define this to
1605		the eMMC device that fastboot should use to store the image.
1606
1607		CONFIG_FASTBOOT_GPT_NAME
1608		The fastboot "flash" command supports writing the downloaded
1609		image to the Protective MBR and the Primary GUID Partition
1610		Table. (Additionally, this downloaded image is post-processed
1611		to generate and write the Backup GUID Partition Table.)
1612		This occurs when the specified "partition name" on the
1613		"fastboot flash" command line matches this value.
1614		The default is "gpt" if undefined.
1615
1616		CONFIG_FASTBOOT_MBR_NAME
1617		The fastboot "flash" command supports writing the downloaded
1618		image to DOS MBR.
1619		This occurs when the "partition name" specified on the
1620		"fastboot flash" command line matches this value.
1621		If not defined the default value "mbr" is used.
1622
1623- Journaling Flash filesystem support:
1624		CONFIG_JFFS2_NAND
1625		Define these for a default partition on a NAND device
1626
1627		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1628		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1629		Define these for a default partition on a NOR device
1630
1631- FAT(File Allocation Table) filesystem write function support:
1632		CONFIG_FAT_WRITE
1633
1634		Define this to enable support for saving memory data as a
1635		file in FAT formatted partition.
1636
1637		This will also enable the command "fatwrite" enabling the
1638		user to write files to FAT.
1639
1640CBFS (Coreboot Filesystem) support
1641		CONFIG_CMD_CBFS
1642
1643		Define this to enable support for reading from a Coreboot
1644		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1645		and cbfsload.
1646
1647- FAT(File Allocation Table) filesystem cluster size:
1648		CONFIG_FS_FAT_MAX_CLUSTSIZE
1649
1650		Define the max cluster size for fat operations else
1651		a default value of 65536 will be defined.
1652
1653- Keyboard Support:
1654		See Kconfig help for available keyboard drivers.
1655
1656		CONFIG_KEYBOARD
1657
1658		Define this to enable a custom keyboard support.
1659		This simply calls drv_keyboard_init() which must be
1660		defined in your board-specific files. This option is deprecated
1661		and is only used by novena. For new boards, use driver model
1662		instead.
1663
1664- Video support:
1665		CONFIG_VIDEO
1666
1667		Define this to enable video support (for output to
1668		video).
1669
1670		CONFIG_VIDEO_CT69000
1671
1672		Enable Chips & Technologies 69000 Video chip
1673
1674		CONFIG_VIDEO_SMI_LYNXEM
1675		Enable Silicon Motion SMI 712/710/810 Video chip. The
1676		video output is selected via environment 'videoout'
1677		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1678		assumed.
1679
1680		For the CT69000 and SMI_LYNXEM drivers, videomode is
1681		selected via environment 'videomode'. Two different ways
1682		are possible:
1683		- "videomode=num"   'num' is a standard LiLo mode numbers.
1684		Following standard modes are supported	(* is default):
1685
1686		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1687		-------------+---------------------------------------------
1688		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1689		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1690		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1691		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1692		-------------+---------------------------------------------
1693		(i.e. setenv videomode 317; saveenv; reset;)
1694
1695		- "videomode=bootargs" all the video parameters are parsed
1696		from the bootargs. (See drivers/video/videomodes.c)
1697
1698
1699		CONFIG_VIDEO_SED13806
1700		Enable Epson SED13806 driver. This driver supports 8bpp
1701		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1702		or CONFIG_VIDEO_SED13806_16BPP
1703
1704		CONFIG_FSL_DIU_FB
1705		Enable the Freescale DIU video driver.	Reference boards for
1706		SOCs that have a DIU should define this macro to enable DIU
1707		support, and should also define these other macros:
1708
1709			CONFIG_SYS_DIU_ADDR
1710			CONFIG_VIDEO
1711			CONFIG_CMD_BMP
1712			CONFIG_CFB_CONSOLE
1713			CONFIG_VIDEO_SW_CURSOR
1714			CONFIG_VGA_AS_SINGLE_DEVICE
1715			CONFIG_VIDEO_LOGO
1716			CONFIG_VIDEO_BMP_LOGO
1717
1718		The DIU driver will look for the 'video-mode' environment
1719		variable, and if defined, enable the DIU as a console during
1720		boot.  See the documentation file doc/README.video for a
1721		description of this variable.
1722
1723- LCD Support:	CONFIG_LCD
1724
1725		Define this to enable LCD support (for output to LCD
1726		display); also select one of the supported displays
1727		by defining one of these:
1728
1729		CONFIG_ATMEL_LCD:
1730
1731			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1732
1733		CONFIG_NEC_NL6448AC33:
1734
1735			NEC NL6448AC33-18. Active, color, single scan.
1736
1737		CONFIG_NEC_NL6448BC20
1738
1739			NEC NL6448BC20-08. 6.5", 640x480.
1740			Active, color, single scan.
1741
1742		CONFIG_NEC_NL6448BC33_54
1743
1744			NEC NL6448BC33-54. 10.4", 640x480.
1745			Active, color, single scan.
1746
1747		CONFIG_SHARP_16x9
1748
1749			Sharp 320x240. Active, color, single scan.
1750			It isn't 16x9, and I am not sure what it is.
1751
1752		CONFIG_SHARP_LQ64D341
1753
1754			Sharp LQ64D341 display, 640x480.
1755			Active, color, single scan.
1756
1757		CONFIG_HLD1045
1758
1759			HLD1045 display, 640x480.
1760			Active, color, single scan.
1761
1762		CONFIG_OPTREX_BW
1763
1764			Optrex	 CBL50840-2 NF-FW 99 22 M5
1765			or
1766			Hitachi	 LMG6912RPFC-00T
1767			or
1768			Hitachi	 SP14Q002
1769
1770			320x240. Black & white.
1771
1772		Normally display is black on white background; define
1773		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1774
1775		CONFIG_LCD_ALIGNMENT
1776
1777		Normally the LCD is page-aligned (typically 4KB). If this is
1778		defined then the LCD will be aligned to this value instead.
1779		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1780		here, since it is cheaper to change data cache settings on
1781		a per-section basis.
1782
1783		CONFIG_CONSOLE_SCROLL_LINES
1784
1785		When the console need to be scrolled, this is the number of
1786		lines to scroll by. It defaults to 1. Increasing this makes
1787		the console jump but can help speed up operation when scrolling
1788		is slow.
1789
1790		CONFIG_LCD_ROTATION
1791
1792		Sometimes, for example if the display is mounted in portrait
1793		mode or even if it's mounted landscape but rotated by 180degree,
1794		we need to rotate our content of the display relative to the
1795		framebuffer, so that user can read the messages which are
1796		printed out.
1797		Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1798		initialized with a given rotation from "vl_rot" out of
1799		"vidinfo_t" which is provided by the board specific code.
1800		The value for vl_rot is coded as following (matching to
1801		fbcon=rotate:<n> linux-kernel commandline):
1802		0 = no rotation respectively 0 degree
1803		1 = 90 degree rotation
1804		2 = 180 degree rotation
1805		3 = 270 degree rotation
1806
1807		If CONFIG_LCD_ROTATION is not defined, the console will be
1808		initialized with 0degree rotation.
1809
1810		CONFIG_LCD_BMP_RLE8
1811
1812		Support drawing of RLE8-compressed bitmaps on the LCD.
1813
1814		CONFIG_I2C_EDID
1815
1816		Enables an 'i2c edid' command which can read EDID
1817		information over I2C from an attached LCD display.
1818
1819- Splash Screen Support: CONFIG_SPLASH_SCREEN
1820
1821		If this option is set, the environment is checked for
1822		a variable "splashimage". If found, the usual display
1823		of logo, copyright and system information on the LCD
1824		is suppressed and the BMP image at the address
1825		specified in "splashimage" is loaded instead. The
1826		console is redirected to the "nulldev", too. This
1827		allows for a "silent" boot where a splash screen is
1828		loaded very quickly after power-on.
1829
1830		CONFIG_SPLASHIMAGE_GUARD
1831
1832		If this option is set, then U-Boot will prevent the environment
1833		variable "splashimage" from being set to a problematic address
1834		(see doc/README.displaying-bmps).
1835		This option is useful for targets where, due to alignment
1836		restrictions, an improperly aligned BMP image will cause a data
1837		abort. If you think you will not have problems with unaligned
1838		accesses (for example because your toolchain prevents them)
1839		there is no need to set this option.
1840
1841		CONFIG_SPLASH_SCREEN_ALIGN
1842
1843		If this option is set the splash image can be freely positioned
1844		on the screen. Environment variable "splashpos" specifies the
1845		position as "x,y". If a positive number is given it is used as
1846		number of pixel from left/top. If a negative number is given it
1847		is used as number of pixel from right/bottom. You can also
1848		specify 'm' for centering the image.
1849
1850		Example:
1851		setenv splashpos m,m
1852			=> image at center of screen
1853
1854		setenv splashpos 30,20
1855			=> image at x = 30 and y = 20
1856
1857		setenv splashpos -10,m
1858			=> vertically centered image
1859			   at x = dspWidth - bmpWidth - 9
1860
1861- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1862
1863		If this option is set, additionally to standard BMP
1864		images, gzipped BMP images can be displayed via the
1865		splashscreen support or the bmp command.
1866
1867- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1868
1869		If this option is set, 8-bit RLE compressed BMP images
1870		can be displayed via the splashscreen support or the
1871		bmp command.
1872
1873- Do compressing for memory range:
1874		CONFIG_CMD_ZIP
1875
1876		If this option is set, it would use zlib deflate method
1877		to compress the specified memory at its best effort.
1878
1879- Compression support:
1880		CONFIG_GZIP
1881
1882		Enabled by default to support gzip compressed images.
1883
1884		CONFIG_BZIP2
1885
1886		If this option is set, support for bzip2 compressed
1887		images is included. If not, only uncompressed and gzip
1888		compressed images are supported.
1889
1890		NOTE: the bzip2 algorithm requires a lot of RAM, so
1891		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1892		be at least 4MB.
1893
1894		CONFIG_LZMA
1895
1896		If this option is set, support for lzma compressed
1897		images is included.
1898
1899		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1900		requires an amount of dynamic memory that is given by the
1901		formula:
1902
1903			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1904
1905		Where lc and lp stand for, respectively, Literal context bits
1906		and Literal pos bits.
1907
1908		This value is upper-bounded by 14MB in the worst case. Anyway,
1909		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1910		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1911		a very small buffer.
1912
1913		Use the lzmainfo tool to determinate the lc and lp values and
1914		then calculate the amount of needed dynamic memory (ensuring
1915		the appropriate CONFIG_SYS_MALLOC_LEN value).
1916
1917		CONFIG_LZO
1918
1919		If this option is set, support for LZO compressed images
1920		is included.
1921
1922- MII/PHY support:
1923		CONFIG_PHY_ADDR
1924
1925		The address of PHY on MII bus.
1926
1927		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1928
1929		The clock frequency of the MII bus
1930
1931		CONFIG_PHY_GIGE
1932
1933		If this option is set, support for speed/duplex
1934		detection of gigabit PHY is included.
1935
1936		CONFIG_PHY_RESET_DELAY
1937
1938		Some PHY like Intel LXT971A need extra delay after
1939		reset before any MII register access is possible.
1940		For such PHY, set this option to the usec delay
1941		required. (minimum 300usec for LXT971A)
1942
1943		CONFIG_PHY_CMD_DELAY (ppc4xx)
1944
1945		Some PHY like Intel LXT971A need extra delay after
1946		command issued before MII status register can be read
1947
1948- IP address:
1949		CONFIG_IPADDR
1950
1951		Define a default value for the IP address to use for
1952		the default Ethernet interface, in case this is not
1953		determined through e.g. bootp.
1954		(Environment variable "ipaddr")
1955
1956- Server IP address:
1957		CONFIG_SERVERIP
1958
1959		Defines a default value for the IP address of a TFTP
1960		server to contact when using the "tftboot" command.
1961		(Environment variable "serverip")
1962
1963		CONFIG_KEEP_SERVERADDR
1964
1965		Keeps the server's MAC address, in the env 'serveraddr'
1966		for passing to bootargs (like Linux's netconsole option)
1967
1968- Gateway IP address:
1969		CONFIG_GATEWAYIP
1970
1971		Defines a default value for the IP address of the
1972		default router where packets to other networks are
1973		sent to.
1974		(Environment variable "gatewayip")
1975
1976- Subnet mask:
1977		CONFIG_NETMASK
1978
1979		Defines a default value for the subnet mask (or
1980		routing prefix) which is used to determine if an IP
1981		address belongs to the local subnet or needs to be
1982		forwarded through a router.
1983		(Environment variable "netmask")
1984
1985- Multicast TFTP Mode:
1986		CONFIG_MCAST_TFTP
1987
1988		Defines whether you want to support multicast TFTP as per
1989		rfc-2090; for example to work with atftp.  Lets lots of targets
1990		tftp down the same boot image concurrently.  Note: the Ethernet
1991		driver in use must provide a function: mcast() to join/leave a
1992		multicast group.
1993
1994- BOOTP Recovery Mode:
1995		CONFIG_BOOTP_RANDOM_DELAY
1996
1997		If you have many targets in a network that try to
1998		boot using BOOTP, you may want to avoid that all
1999		systems send out BOOTP requests at precisely the same
2000		moment (which would happen for instance at recovery
2001		from a power failure, when all systems will try to
2002		boot, thus flooding the BOOTP server. Defining
2003		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
2004		inserted before sending out BOOTP requests. The
2005		following delays are inserted then:
2006
2007		1st BOOTP request:	delay 0 ... 1 sec
2008		2nd BOOTP request:	delay 0 ... 2 sec
2009		3rd BOOTP request:	delay 0 ... 4 sec
2010		4th and following
2011		BOOTP requests:		delay 0 ... 8 sec
2012
2013		CONFIG_BOOTP_ID_CACHE_SIZE
2014
2015		BOOTP packets are uniquely identified using a 32-bit ID. The
2016		server will copy the ID from client requests to responses and
2017		U-Boot will use this to determine if it is the destination of
2018		an incoming response. Some servers will check that addresses
2019		aren't in use before handing them out (usually using an ARP
2020		ping) and therefore take up to a few hundred milliseconds to
2021		respond. Network congestion may also influence the time it
2022		takes for a response to make it back to the client. If that
2023		time is too long, U-Boot will retransmit requests. In order
2024		to allow earlier responses to still be accepted after these
2025		retransmissions, U-Boot's BOOTP client keeps a small cache of
2026		IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
2027		cache. The default is to keep IDs for up to four outstanding
2028		requests. Increasing this will allow U-Boot to accept offers
2029		from a BOOTP client in networks with unusually high latency.
2030
2031- DHCP Advanced Options:
2032		You can fine tune the DHCP functionality by defining
2033		CONFIG_BOOTP_* symbols:
2034
2035		CONFIG_BOOTP_SUBNETMASK
2036		CONFIG_BOOTP_GATEWAY
2037		CONFIG_BOOTP_HOSTNAME
2038		CONFIG_BOOTP_NISDOMAIN
2039		CONFIG_BOOTP_BOOTPATH
2040		CONFIG_BOOTP_BOOTFILESIZE
2041		CONFIG_BOOTP_DNS
2042		CONFIG_BOOTP_DNS2
2043		CONFIG_BOOTP_SEND_HOSTNAME
2044		CONFIG_BOOTP_NTPSERVER
2045		CONFIG_BOOTP_TIMEOFFSET
2046		CONFIG_BOOTP_VENDOREX
2047		CONFIG_BOOTP_MAY_FAIL
2048
2049		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
2050		environment variable, not the BOOTP server.
2051
2052		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
2053		after the configured retry count, the call will fail
2054		instead of starting over.  This can be used to fail over
2055		to Link-local IP address configuration if the DHCP server
2056		is not available.
2057
2058		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
2059		serverip from a DHCP server, it is possible that more
2060		than one DNS serverip is offered to the client.
2061		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
2062		serverip will be stored in the additional environment
2063		variable "dnsip2". The first DNS serverip is always
2064		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
2065		is defined.
2066
2067		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
2068		to do a dynamic update of a DNS server. To do this, they
2069		need the hostname of the DHCP requester.
2070		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
2071		of the "hostname" environment variable is passed as
2072		option 12 to the DHCP server.
2073
2074		CONFIG_BOOTP_DHCP_REQUEST_DELAY
2075
2076		A 32bit value in microseconds for a delay between
2077		receiving a "DHCP Offer" and sending the "DHCP Request".
2078		This fixes a problem with certain DHCP servers that don't
2079		respond 100% of the time to a "DHCP request". E.g. On an
2080		AT91RM9200 processor running at 180MHz, this delay needed
2081		to be *at least* 15,000 usec before a Windows Server 2003
2082		DHCP server would reply 100% of the time. I recommend at
2083		least 50,000 usec to be safe. The alternative is to hope
2084		that one of the retries will be successful but note that
2085		the DHCP timeout and retry process takes a longer than
2086		this delay.
2087
2088 - Link-local IP address negotiation:
2089		Negotiate with other link-local clients on the local network
2090		for an address that doesn't require explicit configuration.
2091		This is especially useful if a DHCP server cannot be guaranteed
2092		to exist in all environments that the device must operate.
2093
2094		See doc/README.link-local for more information.
2095
2096 - CDP Options:
2097		CONFIG_CDP_DEVICE_ID
2098
2099		The device id used in CDP trigger frames.
2100
2101		CONFIG_CDP_DEVICE_ID_PREFIX
2102
2103		A two character string which is prefixed to the MAC address
2104		of the device.
2105
2106		CONFIG_CDP_PORT_ID
2107
2108		A printf format string which contains the ascii name of
2109		the port. Normally is set to "eth%d" which sets
2110		eth0 for the first Ethernet, eth1 for the second etc.
2111
2112		CONFIG_CDP_CAPABILITIES
2113
2114		A 32bit integer which indicates the device capabilities;
2115		0x00000010 for a normal host which does not forwards.
2116
2117		CONFIG_CDP_VERSION
2118
2119		An ascii string containing the version of the software.
2120
2121		CONFIG_CDP_PLATFORM
2122
2123		An ascii string containing the name of the platform.
2124
2125		CONFIG_CDP_TRIGGER
2126
2127		A 32bit integer sent on the trigger.
2128
2129		CONFIG_CDP_POWER_CONSUMPTION
2130
2131		A 16bit integer containing the power consumption of the
2132		device in .1 of milliwatts.
2133
2134		CONFIG_CDP_APPLIANCE_VLAN_TYPE
2135
2136		A byte containing the id of the VLAN.
2137
2138- Status LED:	CONFIG_STATUS_LED
2139
2140		Several configurations allow to display the current
2141		status using a LED. For instance, the LED will blink
2142		fast while running U-Boot code, stop blinking as
2143		soon as a reply to a BOOTP request was received, and
2144		start blinking slow once the Linux kernel is running
2145		(supported by a status LED driver in the Linux
2146		kernel). Defining CONFIG_STATUS_LED enables this
2147		feature in U-Boot.
2148
2149		Additional options:
2150
2151		CONFIG_GPIO_LED
2152		The status LED can be connected to a GPIO pin.
2153		In such cases, the gpio_led driver can be used as a
2154		status LED backend implementation. Define CONFIG_GPIO_LED
2155		to include the gpio_led driver in the U-Boot binary.
2156
2157		CONFIG_GPIO_LED_INVERTED_TABLE
2158		Some GPIO connected LEDs may have inverted polarity in which
2159		case the GPIO high value corresponds to LED off state and
2160		GPIO low value corresponds to LED on state.
2161		In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
2162		with a list of GPIO LEDs that have inverted polarity.
2163
2164- CAN Support:	CONFIG_CAN_DRIVER
2165
2166		Defining CONFIG_CAN_DRIVER enables CAN driver support
2167		on those systems that support this (optional)
2168		feature, like the TQM8xxL modules.
2169
2170- I2C Support:	CONFIG_SYS_I2C
2171
2172		This enable the NEW i2c subsystem, and will allow you to use
2173		i2c commands at the u-boot command line (as long as you set
2174		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
2175		based realtime clock chips or other i2c devices. See
2176		common/cmd_i2c.c for a description of the command line
2177		interface.
2178
2179		ported i2c driver to the new framework:
2180		- drivers/i2c/soft_i2c.c:
2181		  - activate first bus with CONFIG_SYS_I2C_SOFT define
2182		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
2183		    for defining speed and slave address
2184		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
2185		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
2186		    for defining speed and slave address
2187		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
2188		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
2189		    for defining speed and slave address
2190		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
2191		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
2192		    for defining speed and slave address
2193
2194		- drivers/i2c/fsl_i2c.c:
2195		  - activate i2c driver with CONFIG_SYS_I2C_FSL
2196		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
2197		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
2198		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
2199		    bus.
2200		  - If your board supports a second fsl i2c bus, define
2201		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
2202		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
2203		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2204		    second bus.
2205
2206		- drivers/i2c/tegra_i2c.c:
2207		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2208		  - This driver adds 4 i2c buses with a fix speed from
2209		    100000 and the slave addr 0!
2210
2211		- drivers/i2c/ppc4xx_i2c.c
2212		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2213		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2214		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2215
2216		- drivers/i2c/i2c_mxc.c
2217		  - activate this driver with CONFIG_SYS_I2C_MXC
2218		  - enable bus 1 with CONFIG_SYS_I2C_MXC_I2C1
2219		  - enable bus 2 with CONFIG_SYS_I2C_MXC_I2C2
2220		  - enable bus 3 with CONFIG_SYS_I2C_MXC_I2C3
2221		  - enable bus 4 with CONFIG_SYS_I2C_MXC_I2C4
2222		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2223		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2224		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2225		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2226		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2227		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2228		  - define speed for bus 4 with CONFIG_SYS_MXC_I2C4_SPEED
2229		  - define slave for bus 4 with CONFIG_SYS_MXC_I2C4_SLAVE
2230		If those defines are not set, default value is 100000
2231		for speed, and 0 for slave.
2232
2233		- drivers/i2c/rcar_i2c.c:
2234		  - activate this driver with CONFIG_SYS_I2C_RCAR
2235		  - This driver adds 4 i2c buses
2236
2237		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2238		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2239		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2240		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2241		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2242		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2243		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2244		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2245		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2246
2247		- drivers/i2c/sh_i2c.c:
2248		  - activate this driver with CONFIG_SYS_I2C_SH
2249		  - This driver adds from 2 to 5 i2c buses
2250
2251		  - CONFIG_SYS_I2C_SH_BASE0 for setting the register channel 0
2252		  - CONFIG_SYS_I2C_SH_SPEED0 for for the speed channel 0
2253		  - CONFIG_SYS_I2C_SH_BASE1 for setting the register channel 1
2254		  - CONFIG_SYS_I2C_SH_SPEED1 for for the speed channel 1
2255		  - CONFIG_SYS_I2C_SH_BASE2 for setting the register channel 2
2256		  - CONFIG_SYS_I2C_SH_SPEED2 for for the speed channel 2
2257		  - CONFIG_SYS_I2C_SH_BASE3 for setting the register channel 3
2258		  - CONFIG_SYS_I2C_SH_SPEED3 for for the speed channel 3
2259		  - CONFIG_SYS_I2C_SH_BASE4 for setting the register channel 4
2260		  - CONFIG_SYS_I2C_SH_SPEED4 for for the speed channel 4
2261		  - CONFIG_SYS_I2C_SH_NUM_CONTROLLERS for number of i2c buses
2262
2263		- drivers/i2c/omap24xx_i2c.c
2264		  - activate this driver with CONFIG_SYS_I2C_OMAP24XX
2265		  - CONFIG_SYS_OMAP24_I2C_SPEED speed channel 0
2266		  - CONFIG_SYS_OMAP24_I2C_SLAVE slave addr channel 0
2267		  - CONFIG_SYS_OMAP24_I2C_SPEED1 speed channel 1
2268		  - CONFIG_SYS_OMAP24_I2C_SLAVE1 slave addr channel 1
2269		  - CONFIG_SYS_OMAP24_I2C_SPEED2 speed channel 2
2270		  - CONFIG_SYS_OMAP24_I2C_SLAVE2 slave addr channel 2
2271		  - CONFIG_SYS_OMAP24_I2C_SPEED3 speed channel 3
2272		  - CONFIG_SYS_OMAP24_I2C_SLAVE3 slave addr channel 3
2273		  - CONFIG_SYS_OMAP24_I2C_SPEED4 speed channel 4
2274		  - CONFIG_SYS_OMAP24_I2C_SLAVE4 slave addr channel 4
2275
2276		- drivers/i2c/zynq_i2c.c
2277		  - activate this driver with CONFIG_SYS_I2C_ZYNQ
2278		  - set CONFIG_SYS_I2C_ZYNQ_SPEED for speed setting
2279		  - set CONFIG_SYS_I2C_ZYNQ_SLAVE for slave addr
2280
2281		- drivers/i2c/s3c24x0_i2c.c:
2282		  - activate this driver with CONFIG_SYS_I2C_S3C24X0
2283		  - This driver adds i2c buses (11 for Exynos5250, Exynos5420
2284		    9 i2c buses for Exynos4 and 1 for S3C24X0 SoCs from Samsung)
2285		    with a fix speed from 100000 and the slave addr 0!
2286
2287		- drivers/i2c/ihs_i2c.c
2288		  - activate this driver with CONFIG_SYS_I2C_IHS
2289		  - CONFIG_SYS_I2C_IHS_CH0 activate hardware channel 0
2290		  - CONFIG_SYS_I2C_IHS_SPEED_0 speed channel 0
2291		  - CONFIG_SYS_I2C_IHS_SLAVE_0 slave addr channel 0
2292		  - CONFIG_SYS_I2C_IHS_CH1 activate hardware channel 1
2293		  - CONFIG_SYS_I2C_IHS_SPEED_1 speed channel 1
2294		  - CONFIG_SYS_I2C_IHS_SLAVE_1 slave addr channel 1
2295		  - CONFIG_SYS_I2C_IHS_CH2 activate hardware channel 2
2296		  - CONFIG_SYS_I2C_IHS_SPEED_2 speed channel 2
2297		  - CONFIG_SYS_I2C_IHS_SLAVE_2 slave addr channel 2
2298		  - CONFIG_SYS_I2C_IHS_CH3 activate hardware channel 3
2299		  - CONFIG_SYS_I2C_IHS_SPEED_3 speed channel 3
2300		  - CONFIG_SYS_I2C_IHS_SLAVE_3 slave addr channel 3
2301		  - activate dual channel with CONFIG_SYS_I2C_IHS_DUAL
2302		  - CONFIG_SYS_I2C_IHS_SPEED_0_1 speed channel 0_1
2303		  - CONFIG_SYS_I2C_IHS_SLAVE_0_1 slave addr channel 0_1
2304		  - CONFIG_SYS_I2C_IHS_SPEED_1_1 speed channel 1_1
2305		  - CONFIG_SYS_I2C_IHS_SLAVE_1_1 slave addr channel 1_1
2306		  - CONFIG_SYS_I2C_IHS_SPEED_2_1 speed channel 2_1
2307		  - CONFIG_SYS_I2C_IHS_SLAVE_2_1 slave addr channel 2_1
2308		  - CONFIG_SYS_I2C_IHS_SPEED_3_1 speed channel 3_1
2309		  - CONFIG_SYS_I2C_IHS_SLAVE_3_1 slave addr channel 3_1
2310
2311		additional defines:
2312
2313		CONFIG_SYS_NUM_I2C_BUSES
2314		Hold the number of i2c buses you want to use.
2315
2316		CONFIG_SYS_I2C_DIRECT_BUS
2317		define this, if you don't use i2c muxes on your hardware.
2318		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2319		omit this define.
2320
2321		CONFIG_SYS_I2C_MAX_HOPS
2322		define how many muxes are maximal consecutively connected
2323		on one i2c bus. If you not use i2c muxes, omit this
2324		define.
2325
2326		CONFIG_SYS_I2C_BUSES
2327		hold a list of buses you want to use, only used if
2328		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2329		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2330		CONFIG_SYS_NUM_I2C_BUSES = 9:
2331
2332		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2333					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2334					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2335					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2336					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2337					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2338					{1, {I2C_NULL_HOP}}, \
2339					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2340					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2341					}
2342
2343		which defines
2344			bus 0 on adapter 0 without a mux
2345			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2346			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2347			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2348			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2349			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2350			bus 6 on adapter 1 without a mux
2351			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2352			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2353
2354		If you do not have i2c muxes on your board, omit this define.
2355
2356- Legacy I2C Support:	CONFIG_HARD_I2C
2357
2358		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2359		provides the following compelling advantages:
2360
2361		- more than one i2c adapter is usable
2362		- approved multibus support
2363		- better i2c mux support
2364
2365		** Please consider updating your I2C driver now. **
2366
2367		These enable legacy I2C serial bus commands. Defining
2368		CONFIG_HARD_I2C will include the appropriate I2C driver
2369		for the selected CPU.
2370
2371		This will allow you to use i2c commands at the u-boot
2372		command line (as long as you set CONFIG_CMD_I2C in
2373		CONFIG_COMMANDS) and communicate with i2c based realtime
2374		clock chips. See common/cmd_i2c.c for a description of the
2375		command line interface.
2376
2377		CONFIG_HARD_I2C selects a hardware I2C controller.
2378
2379		There are several other quantities that must also be
2380		defined when you define CONFIG_HARD_I2C.
2381
2382		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2383		to be the frequency (in Hz) at which you wish your i2c bus
2384		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2385		the CPU's i2c node address).
2386
2387		Now, the u-boot i2c code for the mpc8xx
2388		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2389		and so its address should therefore be cleared to 0 (See,
2390		eg, MPC823e User's Manual p.16-473). So, set
2391		CONFIG_SYS_I2C_SLAVE to 0.
2392
2393		CONFIG_SYS_I2C_INIT_MPC5XXX
2394
2395		When a board is reset during an i2c bus transfer
2396		chips might think that the current transfer is still
2397		in progress.  Reset the slave devices by sending start
2398		commands until the slave device responds.
2399
2400		That's all that's required for CONFIG_HARD_I2C.
2401
2402		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2403		then the following macros need to be defined (examples are
2404		from include/configs/lwmon.h):
2405
2406		I2C_INIT
2407
2408		(Optional). Any commands necessary to enable the I2C
2409		controller or configure ports.
2410
2411		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2412
2413		I2C_PORT
2414
2415		(Only for MPC8260 CPU). The I/O port to use (the code
2416		assumes both bits are on the same port). Valid values
2417		are 0..3 for ports A..D.
2418
2419		I2C_ACTIVE
2420
2421		The code necessary to make the I2C data line active
2422		(driven).  If the data line is open collector, this
2423		define can be null.
2424
2425		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2426
2427		I2C_TRISTATE
2428
2429		The code necessary to make the I2C data line tri-stated
2430		(inactive).  If the data line is open collector, this
2431		define can be null.
2432
2433		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2434
2435		I2C_READ
2436
2437		Code that returns true if the I2C data line is high,
2438		false if it is low.
2439
2440		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2441
2442		I2C_SDA(bit)
2443
2444		If <bit> is true, sets the I2C data line high. If it
2445		is false, it clears it (low).
2446
2447		eg: #define I2C_SDA(bit) \
2448			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2449			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2450
2451		I2C_SCL(bit)
2452
2453		If <bit> is true, sets the I2C clock line high. If it
2454		is false, it clears it (low).
2455
2456		eg: #define I2C_SCL(bit) \
2457			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2458			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2459
2460		I2C_DELAY
2461
2462		This delay is invoked four times per clock cycle so this
2463		controls the rate of data transfer.  The data rate thus
2464		is 1 / (I2C_DELAY * 4). Often defined to be something
2465		like:
2466
2467		#define I2C_DELAY  udelay(2)
2468
2469		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2470
2471		If your arch supports the generic GPIO framework (asm/gpio.h),
2472		then you may alternatively define the two GPIOs that are to be
2473		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2474		have GPIO-based defaults assigned to them as appropriate.
2475
2476		You should define these to the GPIO value as given directly to
2477		the generic GPIO functions.
2478
2479		CONFIG_SYS_I2C_INIT_BOARD
2480
2481		When a board is reset during an i2c bus transfer
2482		chips might think that the current transfer is still
2483		in progress. On some boards it is possible to access
2484		the i2c SCLK line directly, either by using the
2485		processor pin as a GPIO or by having a second pin
2486		connected to the bus. If this option is defined a
2487		custom i2c_init_board() routine in boards/xxx/board.c
2488		is run early in the boot sequence.
2489
2490		CONFIG_SYS_I2C_BOARD_LATE_INIT
2491
2492		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2493		defined a custom i2c_board_late_init() routine in
2494		boards/xxx/board.c is run AFTER the operations in i2c_init()
2495		is completed. This callpoint can be used to unreset i2c bus
2496		using CPU i2c controller register accesses for CPUs whose i2c
2497		controller provide such a method. It is called at the end of
2498		i2c_init() to allow i2c_init operations to setup the i2c bus
2499		controller on the CPU (e.g. setting bus speed & slave address).
2500
2501		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2502
2503		This option enables configuration of bi_iic_fast[] flags
2504		in u-boot bd_info structure based on u-boot environment
2505		variable "i2cfast". (see also i2cfast)
2506
2507		CONFIG_I2C_MULTI_BUS
2508
2509		This option allows the use of multiple I2C buses, each of which
2510		must have a controller.	 At any point in time, only one bus is
2511		active.	 To switch to a different bus, use the 'i2c dev' command.
2512		Note that bus numbering is zero-based.
2513
2514		CONFIG_SYS_I2C_NOPROBES
2515
2516		This option specifies a list of I2C devices that will be skipped
2517		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2518		is set, specify a list of bus-device pairs.  Otherwise, specify
2519		a 1D array of device addresses
2520
2521		e.g.
2522			#undef	CONFIG_I2C_MULTI_BUS
2523			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2524
2525		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2526
2527			#define CONFIG_I2C_MULTI_BUS
2528			#define CONFIG_SYS_I2C_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2529
2530		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2531
2532		CONFIG_SYS_SPD_BUS_NUM
2533
2534		If defined, then this indicates the I2C bus number for DDR SPD.
2535		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2536
2537		CONFIG_SYS_RTC_BUS_NUM
2538
2539		If defined, then this indicates the I2C bus number for the RTC.
2540		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2541
2542		CONFIG_SYS_DTT_BUS_NUM
2543
2544		If defined, then this indicates the I2C bus number for the DTT.
2545		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2546
2547		CONFIG_SYS_I2C_DTT_ADDR:
2548
2549		If defined, specifies the I2C address of the DTT device.
2550		If not defined, then U-Boot uses predefined value for
2551		specified DTT device.
2552
2553		CONFIG_SOFT_I2C_READ_REPEATED_START
2554
2555		defining this will force the i2c_read() function in
2556		the soft_i2c driver to perform an I2C repeated start
2557		between writing the address pointer and reading the
2558		data.  If this define is omitted the default behaviour
2559		of doing a stop-start sequence will be used.  Most I2C
2560		devices can use either method, but some require one or
2561		the other.
2562
2563- SPI Support:	CONFIG_SPI
2564
2565		Enables SPI driver (so far only tested with
2566		SPI EEPROM, also an instance works with Crystal A/D and
2567		D/As on the SACSng board)
2568
2569		CONFIG_SH_SPI
2570
2571		Enables the driver for SPI controller on SuperH. Currently
2572		only SH7757 is supported.
2573
2574		CONFIG_SOFT_SPI
2575
2576		Enables a software (bit-bang) SPI driver rather than
2577		using hardware support. This is a general purpose
2578		driver that only requires three general I/O port pins
2579		(two outputs, one input) to function. If this is
2580		defined, the board configuration must define several
2581		SPI configuration items (port pins to use, etc). For
2582		an example, see include/configs/sacsng.h.
2583
2584		CONFIG_HARD_SPI
2585
2586		Enables a hardware SPI driver for general-purpose reads
2587		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2588		must define a list of chip-select function pointers.
2589		Currently supported on some MPC8xxx processors.	 For an
2590		example, see include/configs/mpc8349emds.h.
2591
2592		CONFIG_MXC_SPI
2593
2594		Enables the driver for the SPI controllers on i.MX and MXC
2595		SoCs. Currently i.MX31/35/51 are supported.
2596
2597		CONFIG_SYS_SPI_MXC_WAIT
2598		Timeout for waiting until spi transfer completed.
2599		default: (CONFIG_SYS_HZ/100)     /* 10 ms */
2600
2601- FPGA Support: CONFIG_FPGA
2602
2603		Enables FPGA subsystem.
2604
2605		CONFIG_FPGA_<vendor>
2606
2607		Enables support for specific chip vendors.
2608		(ALTERA, XILINX)
2609
2610		CONFIG_FPGA_<family>
2611
2612		Enables support for FPGA family.
2613		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2614
2615		CONFIG_FPGA_COUNT
2616
2617		Specify the number of FPGA devices to support.
2618
2619		CONFIG_CMD_FPGA_LOADMK
2620
2621		Enable support for fpga loadmk command
2622
2623		CONFIG_CMD_FPGA_LOADP
2624
2625		Enable support for fpga loadp command - load partial bitstream
2626
2627		CONFIG_CMD_FPGA_LOADBP
2628
2629		Enable support for fpga loadbp command - load partial bitstream
2630		(Xilinx only)
2631
2632		CONFIG_SYS_FPGA_PROG_FEEDBACK
2633
2634		Enable printing of hash marks during FPGA configuration.
2635
2636		CONFIG_SYS_FPGA_CHECK_BUSY
2637
2638		Enable checks on FPGA configuration interface busy
2639		status by the configuration function. This option
2640		will require a board or device specific function to
2641		be written.
2642
2643		CONFIG_FPGA_DELAY
2644
2645		If defined, a function that provides delays in the FPGA
2646		configuration driver.
2647
2648		CONFIG_SYS_FPGA_CHECK_CTRLC
2649		Allow Control-C to interrupt FPGA configuration
2650
2651		CONFIG_SYS_FPGA_CHECK_ERROR
2652
2653		Check for configuration errors during FPGA bitfile
2654		loading. For example, abort during Virtex II
2655		configuration if the INIT_B line goes low (which
2656		indicated a CRC error).
2657
2658		CONFIG_SYS_FPGA_WAIT_INIT
2659
2660		Maximum time to wait for the INIT_B line to de-assert
2661		after PROB_B has been de-asserted during a Virtex II
2662		FPGA configuration sequence. The default time is 500
2663		ms.
2664
2665		CONFIG_SYS_FPGA_WAIT_BUSY
2666
2667		Maximum time to wait for BUSY to de-assert during
2668		Virtex II FPGA configuration. The default is 5 ms.
2669
2670		CONFIG_SYS_FPGA_WAIT_CONFIG
2671
2672		Time to wait after FPGA configuration. The default is
2673		200 ms.
2674
2675- Configuration Management:
2676		CONFIG_BUILD_TARGET
2677
2678		Some SoCs need special image types (e.g. U-Boot binary
2679		with a special header) as build targets. By defining
2680		CONFIG_BUILD_TARGET in the SoC / board header, this
2681		special image will be automatically built upon calling
2682		make / buildman.
2683
2684		CONFIG_IDENT_STRING
2685
2686		If defined, this string will be added to the U-Boot
2687		version information (U_BOOT_VERSION)
2688
2689- Vendor Parameter Protection:
2690
2691		U-Boot considers the values of the environment
2692		variables "serial#" (Board Serial Number) and
2693		"ethaddr" (Ethernet Address) to be parameters that
2694		are set once by the board vendor / manufacturer, and
2695		protects these variables from casual modification by
2696		the user. Once set, these variables are read-only,
2697		and write or delete attempts are rejected. You can
2698		change this behaviour:
2699
2700		If CONFIG_ENV_OVERWRITE is #defined in your config
2701		file, the write protection for vendor parameters is
2702		completely disabled. Anybody can change or delete
2703		these parameters.
2704
2705		Alternatively, if you define _both_ an ethaddr in the
2706		default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2707		Ethernet address is installed in the environment,
2708		which can be changed exactly ONCE by the user. [The
2709		serial# is unaffected by this, i. e. it remains
2710		read-only.]
2711
2712		The same can be accomplished in a more flexible way
2713		for any variable by configuring the type of access
2714		to allow for those variables in the ".flags" variable
2715		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2716
2717- Protected RAM:
2718		CONFIG_PRAM
2719
2720		Define this variable to enable the reservation of
2721		"protected RAM", i. e. RAM which is not overwritten
2722		by U-Boot. Define CONFIG_PRAM to hold the number of
2723		kB you want to reserve for pRAM. You can overwrite
2724		this default value by defining an environment
2725		variable "pram" to the number of kB you want to
2726		reserve. Note that the board info structure will
2727		still show the full amount of RAM. If pRAM is
2728		reserved, a new environment variable "mem" will
2729		automatically be defined to hold the amount of
2730		remaining RAM in a form that can be passed as boot
2731		argument to Linux, for instance like that:
2732
2733			setenv bootargs ... mem=\${mem}
2734			saveenv
2735
2736		This way you can tell Linux not to use this memory,
2737		either, which results in a memory region that will
2738		not be affected by reboots.
2739
2740		*WARNING* If your board configuration uses automatic
2741		detection of the RAM size, you must make sure that
2742		this memory test is non-destructive. So far, the
2743		following board configurations are known to be
2744		"pRAM-clean":
2745
2746			IVMS8, IVML24, SPD8xx, TQM8xxL,
2747			HERMES, IP860, RPXlite, LWMON,
2748			FLAGADM, TQM8260
2749
2750- Access to physical memory region (> 4GB)
2751		Some basic support is provided for operations on memory not
2752		normally accessible to U-Boot - e.g. some architectures
2753		support access to more than 4GB of memory on 32-bit
2754		machines using physical address extension or similar.
2755		Define CONFIG_PHYSMEM to access this basic support, which
2756		currently only supports clearing the memory.
2757
2758- Error Recovery:
2759		CONFIG_PANIC_HANG
2760
2761		Define this variable to stop the system in case of a
2762		fatal error, so that you have to reset it manually.
2763		This is probably NOT a good idea for an embedded
2764		system where you want the system to reboot
2765		automatically as fast as possible, but it may be
2766		useful during development since you can try to debug
2767		the conditions that lead to the situation.
2768
2769		CONFIG_NET_RETRY_COUNT
2770
2771		This variable defines the number of retries for
2772		network operations like ARP, RARP, TFTP, or BOOTP
2773		before giving up the operation. If not defined, a
2774		default value of 5 is used.
2775
2776		CONFIG_ARP_TIMEOUT
2777
2778		Timeout waiting for an ARP reply in milliseconds.
2779
2780		CONFIG_NFS_TIMEOUT
2781
2782		Timeout in milliseconds used in NFS protocol.
2783		If you encounter "ERROR: Cannot umount" in nfs command,
2784		try longer timeout such as
2785		#define CONFIG_NFS_TIMEOUT 10000UL
2786
2787- Command Interpreter:
2788		CONFIG_AUTO_COMPLETE
2789
2790		Enable auto completion of commands using TAB.
2791
2792		CONFIG_SYS_PROMPT_HUSH_PS2
2793
2794		This defines the secondary prompt string, which is
2795		printed when the command interpreter needs more input
2796		to complete a command. Usually "> ".
2797
2798	Note:
2799
2800		In the current implementation, the local variables
2801		space and global environment variables space are
2802		separated. Local variables are those you define by
2803		simply typing `name=value'. To access a local
2804		variable later on, you have write `$name' or
2805		`${name}'; to execute the contents of a variable
2806		directly type `$name' at the command prompt.
2807
2808		Global environment variables are those you use
2809		setenv/printenv to work with. To run a command stored
2810		in such a variable, you need to use the run command,
2811		and you must not use the '$' sign to access them.
2812
2813		To store commands and special characters in a
2814		variable, please use double quotation marks
2815		surrounding the whole text of the variable, instead
2816		of the backslashes before semicolons and special
2817		symbols.
2818
2819- Command Line Editing and History:
2820		CONFIG_CMDLINE_EDITING
2821
2822		Enable editing and History functions for interactive
2823		command line input operations
2824
2825- Command Line PS1/PS2 support:
2826		CONFIG_CMDLINE_PS_SUPPORT
2827
2828		Enable support for changing the command prompt string
2829		at run-time. Only static string is supported so far.
2830		The string is obtained from environment variables PS1
2831		and PS2.
2832
2833- Default Environment:
2834		CONFIG_EXTRA_ENV_SETTINGS
2835
2836		Define this to contain any number of null terminated
2837		strings (variable = value pairs) that will be part of
2838		the default environment compiled into the boot image.
2839
2840		For example, place something like this in your
2841		board's config file:
2842
2843		#define CONFIG_EXTRA_ENV_SETTINGS \
2844			"myvar1=value1\0" \
2845			"myvar2=value2\0"
2846
2847		Warning: This method is based on knowledge about the
2848		internal format how the environment is stored by the
2849		U-Boot code. This is NOT an official, exported
2850		interface! Although it is unlikely that this format
2851		will change soon, there is no guarantee either.
2852		You better know what you are doing here.
2853
2854		Note: overly (ab)use of the default environment is
2855		discouraged. Make sure to check other ways to preset
2856		the environment like the "source" command or the
2857		boot command first.
2858
2859		CONFIG_ENV_VARS_UBOOT_CONFIG
2860
2861		Define this in order to add variables describing the
2862		U-Boot build configuration to the default environment.
2863		These will be named arch, cpu, board, vendor, and soc.
2864
2865		Enabling this option will cause the following to be defined:
2866
2867		- CONFIG_SYS_ARCH
2868		- CONFIG_SYS_CPU
2869		- CONFIG_SYS_BOARD
2870		- CONFIG_SYS_VENDOR
2871		- CONFIG_SYS_SOC
2872
2873		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2874
2875		Define this in order to add variables describing certain
2876		run-time determined information about the hardware to the
2877		environment.  These will be named board_name, board_rev.
2878
2879		CONFIG_DELAY_ENVIRONMENT
2880
2881		Normally the environment is loaded when the board is
2882		initialised so that it is available to U-Boot. This inhibits
2883		that so that the environment is not available until
2884		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2885		this is instead controlled by the value of
2886		/config/load-environment.
2887
2888- Parallel Flash support:
2889		CONFIG_SYS_NO_FLASH
2890
2891		Traditionally U-Boot was run on systems with parallel NOR
2892		flash. This option is used to disable support for parallel NOR
2893		flash. This option should be defined if the board does not have
2894		parallel flash.
2895
2896		If this option is not defined one of the generic flash drivers
2897		(e.g.  CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be
2898		selected or the board must provide an implementation of the
2899		flash API (see include/flash.h).
2900
2901- DataFlash Support:
2902		CONFIG_HAS_DATAFLASH
2903
2904		Defining this option enables DataFlash features and
2905		allows to read/write in Dataflash via the standard
2906		commands cp, md...
2907
2908- Serial Flash support
2909		CONFIG_CMD_SF
2910
2911		Defining this option enables SPI flash commands
2912		'sf probe/read/write/erase/update'.
2913
2914		Usage requires an initial 'probe' to define the serial
2915		flash parameters, followed by read/write/erase/update
2916		commands.
2917
2918		The following defaults may be provided by the platform
2919		to handle the common case when only a single serial
2920		flash is present on the system.
2921
2922		CONFIG_SF_DEFAULT_BUS		Bus identifier
2923		CONFIG_SF_DEFAULT_CS		Chip-select
2924		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2925		CONFIG_SF_DEFAULT_SPEED		in Hz
2926
2927		CONFIG_CMD_SF_TEST
2928
2929		Define this option to include a destructive SPI flash
2930		test ('sf test').
2931
2932		CONFIG_SF_DUAL_FLASH		Dual flash memories
2933
2934		Define this option to use dual flash support where two flash
2935		memories can be connected with a given cs line.
2936		Currently Xilinx Zynq qspi supports these type of connections.
2937
2938- SystemACE Support:
2939		CONFIG_SYSTEMACE
2940
2941		Adding this option adds support for Xilinx SystemACE
2942		chips attached via some sort of local bus. The address
2943		of the chip must also be defined in the
2944		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2945
2946		#define CONFIG_SYSTEMACE
2947		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2948
2949		When SystemACE support is added, the "ace" device type
2950		becomes available to the fat commands, i.e. fatls.
2951
2952- TFTP Fixed UDP Port:
2953		CONFIG_TFTP_PORT
2954
2955		If this is defined, the environment variable tftpsrcp
2956		is used to supply the TFTP UDP source port value.
2957		If tftpsrcp isn't defined, the normal pseudo-random port
2958		number generator is used.
2959
2960		Also, the environment variable tftpdstp is used to supply
2961		the TFTP UDP destination port value.  If tftpdstp isn't
2962		defined, the normal port 69 is used.
2963
2964		The purpose for tftpsrcp is to allow a TFTP server to
2965		blindly start the TFTP transfer using the pre-configured
2966		target IP address and UDP port. This has the effect of
2967		"punching through" the (Windows XP) firewall, allowing
2968		the remainder of the TFTP transfer to proceed normally.
2969		A better solution is to properly configure the firewall,
2970		but sometimes that is not allowed.
2971
2972- Hashing support:
2973		CONFIG_CMD_HASH
2974
2975		This enables a generic 'hash' command which can produce
2976		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2977
2978		CONFIG_HASH_VERIFY
2979
2980		Enable the hash verify command (hash -v). This adds to code
2981		size a little.
2982
2983		CONFIG_SHA1 - This option enables support of hashing using SHA1
2984		algorithm. The hash is calculated in software.
2985		CONFIG_SHA256 - This option enables support of hashing using
2986		SHA256 algorithm. The hash is calculated in software.
2987		CONFIG_SHA_HW_ACCEL - This option enables hardware acceleration
2988		for SHA1/SHA256 hashing.
2989		This affects the 'hash' command and also the
2990		hash_lookup_algo() function.
2991		CONFIG_SHA_PROG_HW_ACCEL - This option enables
2992		hardware-acceleration for SHA1/SHA256 progressive hashing.
2993		Data can be streamed in a block at a time and the hashing
2994		is performed in hardware.
2995
2996		Note: There is also a sha1sum command, which should perhaps
2997		be deprecated in favour of 'hash sha1'.
2998
2999- Freescale i.MX specific commands:
3000		CONFIG_CMD_HDMIDETECT
3001		This enables 'hdmidet' command which returns true if an
3002		HDMI monitor is detected.  This command is i.MX 6 specific.
3003
3004		CONFIG_CMD_BMODE
3005		This enables the 'bmode' (bootmode) command for forcing
3006		a boot from specific media.
3007
3008		This is useful for forcing the ROM's usb downloader to
3009		activate upon a watchdog reset which is nice when iterating
3010		on U-Boot.  Using the reset button or running bmode normal
3011		will set it back to normal.  This command currently
3012		supports i.MX53 and i.MX6.
3013
3014- bootcount support:
3015		CONFIG_BOOTCOUNT_LIMIT
3016
3017		This enables the bootcounter support, see:
3018		http://www.denx.de/wiki/DULG/UBootBootCountLimit
3019
3020		CONFIG_AT91SAM9XE
3021		enable special bootcounter support on at91sam9xe based boards.
3022		CONFIG_BLACKFIN
3023		enable special bootcounter support on blackfin based boards.
3024		CONFIG_SOC_DA8XX
3025		enable special bootcounter support on da850 based boards.
3026		CONFIG_BOOTCOUNT_RAM
3027		enable support for the bootcounter in RAM
3028		CONFIG_BOOTCOUNT_I2C
3029		enable support for the bootcounter on an i2c (like RTC) device.
3030			CONFIG_SYS_I2C_RTC_ADDR = i2c chip address
3031			CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
3032						    the bootcounter.
3033			CONFIG_BOOTCOUNT_ALEN = address len
3034
3035- Show boot progress:
3036		CONFIG_SHOW_BOOT_PROGRESS
3037
3038		Defining this option allows to add some board-
3039		specific code (calling a user-provided function
3040		"show_boot_progress(int)") that enables you to show
3041		the system's boot progress on some display (for
3042		example, some LED's) on your board. At the moment,
3043		the following checkpoints are implemented:
3044
3045
3046Legacy uImage format:
3047
3048  Arg	Where			When
3049    1	common/cmd_bootm.c	before attempting to boot an image
3050   -1	common/cmd_bootm.c	Image header has bad	 magic number
3051    2	common/cmd_bootm.c	Image header has correct magic number
3052   -2	common/cmd_bootm.c	Image header has bad	 checksum
3053    3	common/cmd_bootm.c	Image header has correct checksum
3054   -3	common/cmd_bootm.c	Image data   has bad	 checksum
3055    4	common/cmd_bootm.c	Image data   has correct checksum
3056   -4	common/cmd_bootm.c	Image is for unsupported architecture
3057    5	common/cmd_bootm.c	Architecture check OK
3058   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
3059    6	common/cmd_bootm.c	Image Type check OK
3060   -6	common/cmd_bootm.c	gunzip uncompression error
3061   -7	common/cmd_bootm.c	Unimplemented compression type
3062    7	common/cmd_bootm.c	Uncompression OK
3063    8	common/cmd_bootm.c	No uncompress/copy overwrite error
3064   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
3065
3066    9	common/image.c		Start initial ramdisk verification
3067  -10	common/image.c		Ramdisk header has bad	   magic number
3068  -11	common/image.c		Ramdisk header has bad	   checksum
3069   10	common/image.c		Ramdisk header is OK
3070  -12	common/image.c		Ramdisk data   has bad	   checksum
3071   11	common/image.c		Ramdisk data   has correct checksum
3072   12	common/image.c		Ramdisk verification complete, start loading
3073  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
3074   13	common/image.c		Start multifile image verification
3075   14	common/image.c		No initial ramdisk, no multifile, continue.
3076
3077   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
3078
3079  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
3080  -31	post/post.c		POST test failed, detected by post_output_backlog()
3081  -32	post/post.c		POST test failed, detected by post_run_single()
3082
3083   34	common/cmd_doc.c	before loading a Image from a DOC device
3084  -35	common/cmd_doc.c	Bad usage of "doc" command
3085   35	common/cmd_doc.c	correct usage of "doc" command
3086  -36	common/cmd_doc.c	No boot device
3087   36	common/cmd_doc.c	correct boot device
3088  -37	common/cmd_doc.c	Unknown Chip ID on boot device
3089   37	common/cmd_doc.c	correct chip ID found, device available
3090  -38	common/cmd_doc.c	Read Error on boot device
3091   38	common/cmd_doc.c	reading Image header from DOC device OK
3092  -39	common/cmd_doc.c	Image header has bad magic number
3093   39	common/cmd_doc.c	Image header has correct magic number
3094  -40	common/cmd_doc.c	Error reading Image from DOC device
3095   40	common/cmd_doc.c	Image header has correct magic number
3096   41	common/cmd_ide.c	before loading a Image from a IDE device
3097  -42	common/cmd_ide.c	Bad usage of "ide" command
3098   42	common/cmd_ide.c	correct usage of "ide" command
3099  -43	common/cmd_ide.c	No boot device
3100   43	common/cmd_ide.c	boot device found
3101  -44	common/cmd_ide.c	Device not available
3102   44	common/cmd_ide.c	Device available
3103  -45	common/cmd_ide.c	wrong partition selected
3104   45	common/cmd_ide.c	partition selected
3105  -46	common/cmd_ide.c	Unknown partition table
3106   46	common/cmd_ide.c	valid partition table found
3107  -47	common/cmd_ide.c	Invalid partition type
3108   47	common/cmd_ide.c	correct partition type
3109  -48	common/cmd_ide.c	Error reading Image Header on boot device
3110   48	common/cmd_ide.c	reading Image Header from IDE device OK
3111  -49	common/cmd_ide.c	Image header has bad magic number
3112   49	common/cmd_ide.c	Image header has correct magic number
3113  -50	common/cmd_ide.c	Image header has bad	 checksum
3114   50	common/cmd_ide.c	Image header has correct checksum
3115  -51	common/cmd_ide.c	Error reading Image from IDE device
3116   51	common/cmd_ide.c	reading Image from IDE device OK
3117   52	common/cmd_nand.c	before loading a Image from a NAND device
3118  -53	common/cmd_nand.c	Bad usage of "nand" command
3119   53	common/cmd_nand.c	correct usage of "nand" command
3120  -54	common/cmd_nand.c	No boot device
3121   54	common/cmd_nand.c	boot device found
3122  -55	common/cmd_nand.c	Unknown Chip ID on boot device
3123   55	common/cmd_nand.c	correct chip ID found, device available
3124  -56	common/cmd_nand.c	Error reading Image Header on boot device
3125   56	common/cmd_nand.c	reading Image Header from NAND device OK
3126  -57	common/cmd_nand.c	Image header has bad magic number
3127   57	common/cmd_nand.c	Image header has correct magic number
3128  -58	common/cmd_nand.c	Error reading Image from NAND device
3129   58	common/cmd_nand.c	reading Image from NAND device OK
3130
3131  -60	common/env_common.c	Environment has a bad CRC, using default
3132
3133   64	net/eth.c		starting with Ethernet configuration.
3134  -64	net/eth.c		no Ethernet found.
3135   65	net/eth.c		Ethernet found.
3136
3137  -80	common/cmd_net.c	usage wrong
3138   80	common/cmd_net.c	before calling net_loop()
3139  -81	common/cmd_net.c	some error in net_loop() occurred
3140   81	common/cmd_net.c	net_loop() back without error
3141  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
3142   82	common/cmd_net.c	trying automatic boot
3143   83	common/cmd_net.c	running "source" command
3144  -83	common/cmd_net.c	some error in automatic boot or "source" command
3145   84	common/cmd_net.c	end without errors
3146
3147FIT uImage format:
3148
3149  Arg	Where			When
3150  100	common/cmd_bootm.c	Kernel FIT Image has correct format
3151 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
3152  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
3153 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
3154  102	common/cmd_bootm.c	Kernel unit name specified
3155 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
3156  103	common/cmd_bootm.c	Found configuration node
3157  104	common/cmd_bootm.c	Got kernel subimage node offset
3158 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
3159  105	common/cmd_bootm.c	Kernel subimage hash verification OK
3160 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
3161  106	common/cmd_bootm.c	Architecture check OK
3162 -106	common/cmd_bootm.c	Kernel subimage has wrong type
3163  107	common/cmd_bootm.c	Kernel subimage type OK
3164 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
3165  108	common/cmd_bootm.c	Got kernel subimage data/size
3166 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
3167 -109	common/cmd_bootm.c	Can't get kernel subimage type
3168 -110	common/cmd_bootm.c	Can't get kernel subimage comp
3169 -111	common/cmd_bootm.c	Can't get kernel subimage os
3170 -112	common/cmd_bootm.c	Can't get kernel subimage load address
3171 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
3172
3173  120	common/image.c		Start initial ramdisk verification
3174 -120	common/image.c		Ramdisk FIT image has incorrect format
3175  121	common/image.c		Ramdisk FIT image has correct format
3176  122	common/image.c		No ramdisk subimage unit name, using configuration
3177 -122	common/image.c		Can't get configuration for ramdisk subimage
3178  123	common/image.c		Ramdisk unit name specified
3179 -124	common/image.c		Can't get ramdisk subimage node offset
3180  125	common/image.c		Got ramdisk subimage node offset
3181 -125	common/image.c		Ramdisk subimage hash verification failed
3182  126	common/image.c		Ramdisk subimage hash verification OK
3183 -126	common/image.c		Ramdisk subimage for unsupported architecture
3184  127	common/image.c		Architecture check OK
3185 -127	common/image.c		Can't get ramdisk subimage data/size
3186  128	common/image.c		Got ramdisk subimage data/size
3187  129	common/image.c		Can't get ramdisk load address
3188 -129	common/image.c		Got ramdisk load address
3189
3190 -130	common/cmd_doc.c	Incorrect FIT image format
3191  131	common/cmd_doc.c	FIT image format OK
3192
3193 -140	common/cmd_ide.c	Incorrect FIT image format
3194  141	common/cmd_ide.c	FIT image format OK
3195
3196 -150	common/cmd_nand.c	Incorrect FIT image format
3197  151	common/cmd_nand.c	FIT image format OK
3198
3199- legacy image format:
3200		CONFIG_IMAGE_FORMAT_LEGACY
3201		enables the legacy image format support in U-Boot.
3202
3203		Default:
3204		enabled if CONFIG_FIT_SIGNATURE is not defined.
3205
3206		CONFIG_DISABLE_IMAGE_LEGACY
3207		disable the legacy image format
3208
3209		This define is introduced, as the legacy image format is
3210		enabled per default for backward compatibility.
3211
3212- FIT image support:
3213		CONFIG_FIT_DISABLE_SHA256
3214		Supporting SHA256 hashes has quite an impact on binary size.
3215		For constrained systems sha256 hash support can be disabled
3216		with this option.
3217
3218		TODO(sjg@chromium.org): Adjust this option to be positive,
3219		and move it to Kconfig
3220
3221- Standalone program support:
3222		CONFIG_STANDALONE_LOAD_ADDR
3223
3224		This option defines a board specific value for the
3225		address where standalone program gets loaded, thus
3226		overwriting the architecture dependent default
3227		settings.
3228
3229- Frame Buffer Address:
3230		CONFIG_FB_ADDR
3231
3232		Define CONFIG_FB_ADDR if you want to use specific
3233		address for frame buffer.  This is typically the case
3234		when using a graphics controller has separate video
3235		memory.  U-Boot will then place the frame buffer at
3236		the given address instead of dynamically reserving it
3237		in system RAM by calling lcd_setmem(), which grabs
3238		the memory for the frame buffer depending on the
3239		configured panel size.
3240
3241		Please see board_init_f function.
3242
3243- Automatic software updates via TFTP server
3244		CONFIG_UPDATE_TFTP
3245		CONFIG_UPDATE_TFTP_CNT_MAX
3246		CONFIG_UPDATE_TFTP_MSEC_MAX
3247
3248		These options enable and control the auto-update feature;
3249		for a more detailed description refer to doc/README.update.
3250
3251- MTD Support (mtdparts command, UBI support)
3252		CONFIG_MTD_DEVICE
3253
3254		Adds the MTD device infrastructure from the Linux kernel.
3255		Needed for mtdparts command support.
3256
3257		CONFIG_MTD_PARTITIONS
3258
3259		Adds the MTD partitioning infrastructure from the Linux
3260		kernel. Needed for UBI support.
3261
3262- UBI support
3263		CONFIG_CMD_UBI
3264
3265		Adds commands for interacting with MTD partitions formatted
3266		with the UBI flash translation layer
3267
3268		Requires also defining CONFIG_RBTREE
3269
3270		CONFIG_UBI_SILENCE_MSG
3271
3272		Make the verbose messages from UBI stop printing.  This leaves
3273		warnings and errors enabled.
3274
3275
3276		CONFIG_MTD_UBI_WL_THRESHOLD
3277		This parameter defines the maximum difference between the highest
3278		erase counter value and the lowest erase counter value of eraseblocks
3279		of UBI devices. When this threshold is exceeded, UBI starts performing
3280		wear leveling by means of moving data from eraseblock with low erase
3281		counter to eraseblocks with high erase counter.
3282
3283		The default value should be OK for SLC NAND flashes, NOR flashes and
3284		other flashes which have eraseblock life-cycle 100000 or more.
3285		However, in case of MLC NAND flashes which typically have eraseblock
3286		life-cycle less than 10000, the threshold should be lessened (e.g.,
3287		to 128 or 256, although it does not have to be power of 2).
3288
3289		default: 4096
3290
3291		CONFIG_MTD_UBI_BEB_LIMIT
3292		This option specifies the maximum bad physical eraseblocks UBI
3293		expects on the MTD device (per 1024 eraseblocks). If the
3294		underlying flash does not admit of bad eraseblocks (e.g. NOR
3295		flash), this value is ignored.
3296
3297		NAND datasheets often specify the minimum and maximum NVM
3298		(Number of Valid Blocks) for the flashes' endurance lifetime.
3299		The maximum expected bad eraseblocks per 1024 eraseblocks
3300		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
3301		which gives 20 for most NANDs (MaxNVB is basically the total
3302		count of eraseblocks on the chip).
3303
3304		To put it differently, if this value is 20, UBI will try to
3305		reserve about 1.9% of physical eraseblocks for bad blocks
3306		handling. And that will be 1.9% of eraseblocks on the entire
3307		NAND chip, not just the MTD partition UBI attaches. This means
3308		that if you have, say, a NAND flash chip admits maximum 40 bad
3309		eraseblocks, and it is split on two MTD partitions of the same
3310		size, UBI will reserve 40 eraseblocks when attaching a
3311		partition.
3312
3313		default: 20
3314
3315		CONFIG_MTD_UBI_FASTMAP
3316		Fastmap is a mechanism which allows attaching an UBI device
3317		in nearly constant time. Instead of scanning the whole MTD device it
3318		only has to locate a checkpoint (called fastmap) on the device.
3319		The on-flash fastmap contains all information needed to attach
3320		the device. Using fastmap makes only sense on large devices where
3321		attaching by scanning takes long. UBI will not automatically install
3322		a fastmap on old images, but you can set the UBI parameter
3323		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
3324		that fastmap-enabled images are still usable with UBI implementations
3325		without	fastmap support. On typical flash devices the whole fastmap
3326		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
3327
3328		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
3329		Set this parameter to enable fastmap automatically on images
3330		without a fastmap.
3331		default: 0
3332
3333		CONFIG_MTD_UBI_FM_DEBUG
3334		Enable UBI fastmap debug
3335		default: 0
3336
3337- UBIFS support
3338		CONFIG_CMD_UBIFS
3339
3340		Adds commands for interacting with UBI volumes formatted as
3341		UBIFS.  UBIFS is read-only in u-boot.
3342
3343		Requires UBI support as well as CONFIG_LZO
3344
3345		CONFIG_UBIFS_SILENCE_MSG
3346
3347		Make the verbose messages from UBIFS stop printing.  This leaves
3348		warnings and errors enabled.
3349
3350- SPL framework
3351		CONFIG_SPL
3352		Enable building of SPL globally.
3353
3354		CONFIG_SPL_LDSCRIPT
3355		LDSCRIPT for linking the SPL binary.
3356
3357		CONFIG_SPL_MAX_FOOTPRINT
3358		Maximum size in memory allocated to the SPL, BSS included.
3359		When defined, the linker checks that the actual memory
3360		used by SPL from _start to __bss_end does not exceed it.
3361		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3362		must not be both defined at the same time.
3363
3364		CONFIG_SPL_MAX_SIZE
3365		Maximum size of the SPL image (text, data, rodata, and
3366		linker lists sections), BSS excluded.
3367		When defined, the linker checks that the actual size does
3368		not exceed it.
3369
3370		CONFIG_SPL_TEXT_BASE
3371		TEXT_BASE for linking the SPL binary.
3372
3373		CONFIG_SPL_RELOC_TEXT_BASE
3374		Address to relocate to.  If unspecified, this is equal to
3375		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3376
3377		CONFIG_SPL_BSS_START_ADDR
3378		Link address for the BSS within the SPL binary.
3379
3380		CONFIG_SPL_BSS_MAX_SIZE
3381		Maximum size in memory allocated to the SPL BSS.
3382		When defined, the linker checks that the actual memory used
3383		by SPL from __bss_start to __bss_end does not exceed it.
3384		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3385		must not be both defined at the same time.
3386
3387		CONFIG_SPL_STACK
3388		Adress of the start of the stack SPL will use
3389
3390		CONFIG_SPL_PANIC_ON_RAW_IMAGE
3391		When defined, SPL will panic() if the image it has
3392		loaded does not have a signature.
3393		Defining this is useful when code which loads images
3394		in SPL cannot guarantee that absolutely all read errors
3395		will be caught.
3396		An example is the LPC32XX MLC NAND driver, which will
3397		consider that a completely unreadable NAND block is bad,
3398		and thus should be skipped silently.
3399
3400		CONFIG_SPL_ABORT_ON_RAW_IMAGE
3401		When defined, SPL will proceed to another boot method
3402		if the image it has loaded does not have a signature.
3403
3404		CONFIG_SPL_RELOC_STACK
3405		Adress of the start of the stack SPL will use after
3406		relocation.  If unspecified, this is equal to
3407		CONFIG_SPL_STACK.
3408
3409		CONFIG_SYS_SPL_MALLOC_START
3410		Starting address of the malloc pool used in SPL.
3411		When this option is set the full malloc is used in SPL and
3412		it is set up by spl_init() and before that, the simple malloc()
3413		can be used if CONFIG_SYS_MALLOC_F is defined.
3414
3415		CONFIG_SYS_SPL_MALLOC_SIZE
3416		The size of the malloc pool used in SPL.
3417
3418		CONFIG_SPL_FRAMEWORK
3419		Enable the SPL framework under common/.  This framework
3420		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3421		NAND loading of the Linux Kernel.
3422
3423		CONFIG_SPL_OS_BOOT
3424		Enable booting directly to an OS from SPL.
3425		See also: doc/README.falcon
3426
3427		CONFIG_SPL_DISPLAY_PRINT
3428		For ARM, enable an optional function to print more information
3429		about the running system.
3430
3431		CONFIG_SPL_INIT_MINIMAL
3432		Arch init code should be built for a very small image
3433
3434		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3435		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3436		Address and partition on the MMC to load U-Boot from
3437		when the MMC is being used in raw mode.
3438
3439		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
3440		Partition on the MMC to load U-Boot from when the MMC is being
3441		used in raw mode
3442
3443		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3444		Sector to load kernel uImage from when MMC is being
3445		used in raw mode (for Falcon mode)
3446
3447		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3448		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3449		Sector and number of sectors to load kernel argument
3450		parameters from when MMC is being used in raw mode
3451		(for falcon mode)
3452
3453		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
3454		Partition on the MMC to load U-Boot from when the MMC is being
3455		used in fs mode
3456
3457		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
3458		Filename to read to load U-Boot when reading from filesystem
3459
3460		CONFIG_SPL_FS_LOAD_KERNEL_NAME
3461		Filename to read to load kernel uImage when reading
3462		from filesystem (for Falcon mode)
3463
3464		CONFIG_SPL_FS_LOAD_ARGS_NAME
3465		Filename to read to load kernel argument parameters
3466		when reading from filesystem (for Falcon mode)
3467
3468		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3469		Set this for NAND SPL on PPC mpc83xx targets, so that
3470		start.S waits for the rest of the SPL to load before
3471		continuing (the hardware starts execution after just
3472		loading the first page rather than the full 4K).
3473
3474		CONFIG_SPL_SKIP_RELOCATE
3475		Avoid SPL relocation
3476
3477		CONFIG_SPL_NAND_BASE
3478		Include nand_base.c in the SPL.  Requires
3479		CONFIG_SPL_NAND_DRIVERS.
3480
3481		CONFIG_SPL_NAND_DRIVERS
3482		SPL uses normal NAND drivers, not minimal drivers.
3483
3484		CONFIG_SPL_NAND_ECC
3485		Include standard software ECC in the SPL
3486
3487		CONFIG_SPL_NAND_SIMPLE
3488		Support for NAND boot using simple NAND drivers that
3489		expose the cmd_ctrl() interface.
3490
3491		CONFIG_SPL_UBI
3492		Support for a lightweight UBI (fastmap) scanner and
3493		loader
3494
3495		CONFIG_SPL_NAND_RAW_ONLY
3496		Support to boot only raw u-boot.bin images. Use this only
3497		if you need to save space.
3498
3499		CONFIG_SPL_COMMON_INIT_DDR
3500		Set for common ddr init with serial presence detect in
3501		SPL binary.
3502
3503		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3504		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3505		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3506		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3507		CONFIG_SYS_NAND_ECCBYTES
3508		Defines the size and behavior of the NAND that SPL uses
3509		to read U-Boot
3510
3511		CONFIG_SPL_NAND_BOOT
3512		Add support NAND boot
3513
3514		CONFIG_SYS_NAND_U_BOOT_OFFS
3515		Location in NAND to read U-Boot from
3516
3517		CONFIG_SYS_NAND_U_BOOT_DST
3518		Location in memory to load U-Boot to
3519
3520		CONFIG_SYS_NAND_U_BOOT_SIZE
3521		Size of image to load
3522
3523		CONFIG_SYS_NAND_U_BOOT_START
3524		Entry point in loaded image to jump to
3525
3526		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3527		Define this if you need to first read the OOB and then the
3528		data. This is used, for example, on davinci platforms.
3529
3530		CONFIG_SPL_OMAP3_ID_NAND
3531		Support for an OMAP3-specific set of functions to return the
3532		ID and MFR of the first attached NAND chip, if present.
3533
3534		CONFIG_SPL_RAM_DEVICE
3535		Support for running image already present in ram, in SPL binary
3536
3537		CONFIG_SPL_PAD_TO
3538		Image offset to which the SPL should be padded before appending
3539		the SPL payload. By default, this is defined as
3540		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3541		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3542		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3543
3544		CONFIG_SPL_TARGET
3545		Final target image containing SPL and payload.  Some SPLs
3546		use an arch-specific makefile fragment instead, for
3547		example if more than one image needs to be produced.
3548
3549		CONFIG_FIT_SPL_PRINT
3550		Printing information about a FIT image adds quite a bit of
3551		code to SPL. So this is normally disabled in SPL. Use this
3552		option to re-enable it. This will affect the output of the
3553		bootm command when booting a FIT image.
3554
3555- TPL framework
3556		CONFIG_TPL
3557		Enable building of TPL globally.
3558
3559		CONFIG_TPL_PAD_TO
3560		Image offset to which the TPL should be padded before appending
3561		the TPL payload. By default, this is defined as
3562		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3563		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3564		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3565
3566- Interrupt support (PPC):
3567
3568		There are common interrupt_init() and timer_interrupt()
3569		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3570		for CPU specific initialization. interrupt_init_cpu()
3571		should set decrementer_count to appropriate value. If
3572		CPU resets decrementer automatically after interrupt
3573		(ppc4xx) it should set decrementer_count to zero.
3574		timer_interrupt() calls timer_interrupt_cpu() for CPU
3575		specific handling. If board has watchdog / status_led
3576		/ other_activity_monitor it works automatically from
3577		general timer_interrupt().
3578
3579
3580Board initialization settings:
3581------------------------------
3582
3583During Initialization u-boot calls a number of board specific functions
3584to allow the preparation of board specific prerequisites, e.g. pin setup
3585before drivers are initialized. To enable these callbacks the
3586following configuration macros have to be defined. Currently this is
3587architecture specific, so please check arch/your_architecture/lib/board.c
3588typically in board_init_f() and board_init_r().
3589
3590- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3591- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3592- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3593- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3594
3595Configuration Settings:
3596-----------------------
3597
3598- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
3599		Optionally it can be defined to support 64-bit memory commands.
3600
3601- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3602		undefine this when you're short of memory.
3603
3604- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3605		width of the commands listed in the 'help' command output.
3606
3607- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3608		prompt for user input.
3609
3610- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3611
3612- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3613
3614- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3615
3616- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3617		the application (usually a Linux kernel) when it is
3618		booted
3619
3620- CONFIG_SYS_BAUDRATE_TABLE:
3621		List of legal baudrate settings for this board.
3622
3623- CONFIG_SYS_CONSOLE_INFO_QUIET
3624		Suppress display of console information at boot.
3625
3626- CONFIG_SYS_CONSOLE_IS_IN_ENV
3627		If the board specific function
3628			extern int overwrite_console (void);
3629		returns 1, the stdin, stderr and stdout are switched to the
3630		serial port, else the settings in the environment are used.
3631
3632- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3633		Enable the call to overwrite_console().
3634
3635- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3636		Enable overwrite of previous console environment settings.
3637
3638- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3639		Begin and End addresses of the area used by the
3640		simple memory test.
3641
3642- CONFIG_SYS_ALT_MEMTEST:
3643		Enable an alternate, more extensive memory test.
3644
3645- CONFIG_SYS_MEMTEST_SCRATCH:
3646		Scratch address used by the alternate memory test
3647		You only need to set this if address zero isn't writeable
3648
3649- CONFIG_SYS_MEM_RESERVE_SECURE
3650		Only implemented for ARMv8 for now.
3651		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
3652		is substracted from total RAM and won't be reported to OS.
3653		This memory can be used as secure memory. A variable
3654		gd->arch.secure_ram is used to track the location. In systems
3655		the RAM base is not zero, or RAM is divided into banks,
3656		this variable needs to be recalcuated to get the address.
3657
3658- CONFIG_SYS_MEM_TOP_HIDE:
3659		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3660		this specified memory area will get subtracted from the top
3661		(end) of RAM and won't get "touched" at all by U-Boot. By
3662		fixing up gd->ram_size the Linux kernel should gets passed
3663		the now "corrected" memory size and won't touch it either.
3664		This should work for arch/ppc and arch/powerpc. Only Linux
3665		board ports in arch/powerpc with bootwrapper support that
3666		recalculate the memory size from the SDRAM controller setup
3667		will have to get fixed in Linux additionally.
3668
3669		This option can be used as a workaround for the 440EPx/GRx
3670		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3671		be touched.
3672
3673		WARNING: Please make sure that this value is a multiple of
3674		the Linux page size (normally 4k). If this is not the case,
3675		then the end address of the Linux memory will be located at a
3676		non page size aligned address and this could cause major
3677		problems.
3678
3679- CONFIG_SYS_LOADS_BAUD_CHANGE:
3680		Enable temporary baudrate change while serial download
3681
3682- CONFIG_SYS_SDRAM_BASE:
3683		Physical start address of SDRAM. _Must_ be 0 here.
3684
3685- CONFIG_SYS_FLASH_BASE:
3686		Physical start address of Flash memory.
3687
3688- CONFIG_SYS_MONITOR_BASE:
3689		Physical start address of boot monitor code (set by
3690		make config files to be same as the text base address
3691		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3692		CONFIG_SYS_FLASH_BASE when booting from flash.
3693
3694- CONFIG_SYS_MONITOR_LEN:
3695		Size of memory reserved for monitor code, used to
3696		determine _at_compile_time_ (!) if the environment is
3697		embedded within the U-Boot image, or in a separate
3698		flash sector.
3699
3700- CONFIG_SYS_MALLOC_LEN:
3701		Size of DRAM reserved for malloc() use.
3702
3703- CONFIG_SYS_MALLOC_F_LEN
3704		Size of the malloc() pool for use before relocation. If
3705		this is defined, then a very simple malloc() implementation
3706		will become available before relocation. The address is just
3707		below the global data, and the stack is moved down to make
3708		space.
3709
3710		This feature allocates regions with increasing addresses
3711		within the region. calloc() is supported, but realloc()
3712		is not available. free() is supported but does nothing.
3713		The memory will be freed (or in fact just forgotten) when
3714		U-Boot relocates itself.
3715
3716- CONFIG_SYS_MALLOC_SIMPLE
3717		Provides a simple and small malloc() and calloc() for those
3718		boards which do not use the full malloc in SPL (which is
3719		enabled with CONFIG_SYS_SPL_MALLOC_START).
3720
3721- CONFIG_SYS_NONCACHED_MEMORY:
3722		Size of non-cached memory area. This area of memory will be
3723		typically located right below the malloc() area and mapped
3724		uncached in the MMU. This is useful for drivers that would
3725		otherwise require a lot of explicit cache maintenance. For
3726		some drivers it's also impossible to properly maintain the
3727		cache. For example if the regions that need to be flushed
3728		are not a multiple of the cache-line size, *and* padding
3729		cannot be allocated between the regions to align them (i.e.
3730		if the HW requires a contiguous array of regions, and the
3731		size of each region is not cache-aligned), then a flush of
3732		one region may result in overwriting data that hardware has
3733		written to another region in the same cache-line. This can
3734		happen for example in network drivers where descriptors for
3735		buffers are typically smaller than the CPU cache-line (e.g.
3736		16 bytes vs. 32 or 64 bytes).
3737
3738		Non-cached memory is only supported on 32-bit ARM at present.
3739
3740- CONFIG_SYS_BOOTM_LEN:
3741		Normally compressed uImages are limited to an
3742		uncompressed size of 8 MBytes. If this is not enough,
3743		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3744		to adjust this setting to your needs.
3745
3746- CONFIG_SYS_BOOTMAPSZ:
3747		Maximum size of memory mapped by the startup code of
3748		the Linux kernel; all data that must be processed by
3749		the Linux kernel (bd_info, boot arguments, FDT blob if
3750		used) must be put below this limit, unless "bootm_low"
3751		environment variable is defined and non-zero. In such case
3752		all data for the Linux kernel must be between "bootm_low"
3753		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3754		variable "bootm_mapsize" will override the value of
3755		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3756		then the value in "bootm_size" will be used instead.
3757
3758- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3759		Enable initrd_high functionality.  If defined then the
3760		initrd_high feature is enabled and the bootm ramdisk subcommand
3761		is enabled.
3762
3763- CONFIG_SYS_BOOT_GET_CMDLINE:
3764		Enables allocating and saving kernel cmdline in space between
3765		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3766
3767- CONFIG_SYS_BOOT_GET_KBD:
3768		Enables allocating and saving a kernel copy of the bd_info in
3769		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3770
3771- CONFIG_SYS_MAX_FLASH_BANKS:
3772		Max number of Flash memory banks
3773
3774- CONFIG_SYS_MAX_FLASH_SECT:
3775		Max number of sectors on a Flash chip
3776
3777- CONFIG_SYS_FLASH_ERASE_TOUT:
3778		Timeout for Flash erase operations (in ms)
3779
3780- CONFIG_SYS_FLASH_WRITE_TOUT:
3781		Timeout for Flash write operations (in ms)
3782
3783- CONFIG_SYS_FLASH_LOCK_TOUT
3784		Timeout for Flash set sector lock bit operation (in ms)
3785
3786- CONFIG_SYS_FLASH_UNLOCK_TOUT
3787		Timeout for Flash clear lock bits operation (in ms)
3788
3789- CONFIG_SYS_FLASH_PROTECTION
3790		If defined, hardware flash sectors protection is used
3791		instead of U-Boot software protection.
3792
3793- CONFIG_SYS_DIRECT_FLASH_TFTP:
3794
3795		Enable TFTP transfers directly to flash memory;
3796		without this option such a download has to be
3797		performed in two steps: (1) download to RAM, and (2)
3798		copy from RAM to flash.
3799
3800		The two-step approach is usually more reliable, since
3801		you can check if the download worked before you erase
3802		the flash, but in some situations (when system RAM is
3803		too limited to allow for a temporary copy of the
3804		downloaded image) this option may be very useful.
3805
3806- CONFIG_SYS_FLASH_CFI:
3807		Define if the flash driver uses extra elements in the
3808		common flash structure for storing flash geometry.
3809
3810- CONFIG_FLASH_CFI_DRIVER
3811		This option also enables the building of the cfi_flash driver
3812		in the drivers directory
3813
3814- CONFIG_FLASH_CFI_MTD
3815		This option enables the building of the cfi_mtd driver
3816		in the drivers directory. The driver exports CFI flash
3817		to the MTD layer.
3818
3819- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3820		Use buffered writes to flash.
3821
3822- CONFIG_FLASH_SPANSION_S29WS_N
3823		s29ws-n MirrorBit flash has non-standard addresses for buffered
3824		write commands.
3825
3826- CONFIG_SYS_FLASH_QUIET_TEST
3827		If this option is defined, the common CFI flash doesn't
3828		print it's warning upon not recognized FLASH banks. This
3829		is useful, if some of the configured banks are only
3830		optionally available.
3831
3832- CONFIG_FLASH_SHOW_PROGRESS
3833		If defined (must be an integer), print out countdown
3834		digits and dots.  Recommended value: 45 (9..1) for 80
3835		column displays, 15 (3..1) for 40 column displays.
3836
3837- CONFIG_FLASH_VERIFY
3838		If defined, the content of the flash (destination) is compared
3839		against the source after the write operation. An error message
3840		will be printed when the contents are not identical.
3841		Please note that this option is useless in nearly all cases,
3842		since such flash programming errors usually are detected earlier
3843		while unprotecting/erasing/programming. Please only enable
3844		this option if you really know what you are doing.
3845
3846- CONFIG_SYS_RX_ETH_BUFFER:
3847		Defines the number of Ethernet receive buffers. On some
3848		Ethernet controllers it is recommended to set this value
3849		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3850		buffers can be full shortly after enabling the interface
3851		on high Ethernet traffic.
3852		Defaults to 4 if not defined.
3853
3854- CONFIG_ENV_MAX_ENTRIES
3855
3856	Maximum number of entries in the hash table that is used
3857	internally to store the environment settings. The default
3858	setting is supposed to be generous and should work in most
3859	cases. This setting can be used to tune behaviour; see
3860	lib/hashtable.c for details.
3861
3862- CONFIG_ENV_FLAGS_LIST_DEFAULT
3863- CONFIG_ENV_FLAGS_LIST_STATIC
3864	Enable validation of the values given to environment variables when
3865	calling env set.  Variables can be restricted to only decimal,
3866	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3867	the variables can also be restricted to IP address or MAC address.
3868
3869	The format of the list is:
3870		type_attribute = [s|d|x|b|i|m]
3871		access_attribute = [a|r|o|c]
3872		attributes = type_attribute[access_attribute]
3873		entry = variable_name[:attributes]
3874		list = entry[,list]
3875
3876	The type attributes are:
3877		s - String (default)
3878		d - Decimal
3879		x - Hexadecimal
3880		b - Boolean ([1yYtT|0nNfF])
3881		i - IP address
3882		m - MAC address
3883
3884	The access attributes are:
3885		a - Any (default)
3886		r - Read-only
3887		o - Write-once
3888		c - Change-default
3889
3890	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3891		Define this to a list (string) to define the ".flags"
3892		environment variable in the default or embedded environment.
3893
3894	- CONFIG_ENV_FLAGS_LIST_STATIC
3895		Define this to a list (string) to define validation that
3896		should be done if an entry is not found in the ".flags"
3897		environment variable.  To override a setting in the static
3898		list, simply add an entry for the same variable name to the
3899		".flags" variable.
3900
3901	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
3902	regular expression. This allows multiple variables to define the same
3903	flags without explicitly listing them for each variable.
3904
3905- CONFIG_ENV_ACCESS_IGNORE_FORCE
3906	If defined, don't allow the -f switch to env set override variable
3907	access flags.
3908
3909- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3910	This is set by OMAP boards for the max time that reset should
3911	be asserted. See doc/README.omap-reset-time for details on how
3912	the value can be calculated on a given board.
3913
3914- CONFIG_USE_STDINT
3915	If stdint.h is available with your toolchain you can define this
3916	option to enable it. You can provide option 'USE_STDINT=1' when
3917	building U-Boot to enable this.
3918
3919The following definitions that deal with the placement and management
3920of environment data (variable area); in general, we support the
3921following configurations:
3922
3923- CONFIG_BUILD_ENVCRC:
3924
3925	Builds up envcrc with the target environment so that external utils
3926	may easily extract it and embed it in final U-Boot images.
3927
3928- CONFIG_ENV_IS_IN_FLASH:
3929
3930	Define this if the environment is in flash memory.
3931
3932	a) The environment occupies one whole flash sector, which is
3933	   "embedded" in the text segment with the U-Boot code. This
3934	   happens usually with "bottom boot sector" or "top boot
3935	   sector" type flash chips, which have several smaller
3936	   sectors at the start or the end. For instance, such a
3937	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3938	   such a case you would place the environment in one of the
3939	   4 kB sectors - with U-Boot code before and after it. With
3940	   "top boot sector" type flash chips, you would put the
3941	   environment in one of the last sectors, leaving a gap
3942	   between U-Boot and the environment.
3943
3944	- CONFIG_ENV_OFFSET:
3945
3946	   Offset of environment data (variable area) to the
3947	   beginning of flash memory; for instance, with bottom boot
3948	   type flash chips the second sector can be used: the offset
3949	   for this sector is given here.
3950
3951	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3952
3953	- CONFIG_ENV_ADDR:
3954
3955	   This is just another way to specify the start address of
3956	   the flash sector containing the environment (instead of
3957	   CONFIG_ENV_OFFSET).
3958
3959	- CONFIG_ENV_SECT_SIZE:
3960
3961	   Size of the sector containing the environment.
3962
3963
3964	b) Sometimes flash chips have few, equal sized, BIG sectors.
3965	   In such a case you don't want to spend a whole sector for
3966	   the environment.
3967
3968	- CONFIG_ENV_SIZE:
3969
3970	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3971	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3972	   of this flash sector for the environment. This saves
3973	   memory for the RAM copy of the environment.
3974
3975	   It may also save flash memory if you decide to use this
3976	   when your environment is "embedded" within U-Boot code,
3977	   since then the remainder of the flash sector could be used
3978	   for U-Boot code. It should be pointed out that this is
3979	   STRONGLY DISCOURAGED from a robustness point of view:
3980	   updating the environment in flash makes it always
3981	   necessary to erase the WHOLE sector. If something goes
3982	   wrong before the contents has been restored from a copy in
3983	   RAM, your target system will be dead.
3984
3985	- CONFIG_ENV_ADDR_REDUND
3986	  CONFIG_ENV_SIZE_REDUND
3987
3988	   These settings describe a second storage area used to hold
3989	   a redundant copy of the environment data, so that there is
3990	   a valid backup copy in case there is a power failure during
3991	   a "saveenv" operation.
3992
3993BE CAREFUL! Any changes to the flash layout, and some changes to the
3994source code will make it necessary to adapt <board>/u-boot.lds*
3995accordingly!
3996
3997
3998- CONFIG_ENV_IS_IN_NVRAM:
3999
4000	Define this if you have some non-volatile memory device
4001	(NVRAM, battery buffered SRAM) which you want to use for the
4002	environment.
4003
4004	- CONFIG_ENV_ADDR:
4005	- CONFIG_ENV_SIZE:
4006
4007	  These two #defines are used to determine the memory area you
4008	  want to use for environment. It is assumed that this memory
4009	  can just be read and written to, without any special
4010	  provision.
4011
4012BE CAREFUL! The first access to the environment happens quite early
4013in U-Boot initialization (when we try to get the setting of for the
4014console baudrate). You *MUST* have mapped your NVRAM area then, or
4015U-Boot will hang.
4016
4017Please note that even with NVRAM we still use a copy of the
4018environment in RAM: we could work on NVRAM directly, but we want to
4019keep settings there always unmodified except somebody uses "saveenv"
4020to save the current settings.
4021
4022
4023- CONFIG_ENV_IS_IN_EEPROM:
4024
4025	Use this if you have an EEPROM or similar serial access
4026	device and a driver for it.
4027
4028	- CONFIG_ENV_OFFSET:
4029	- CONFIG_ENV_SIZE:
4030
4031	  These two #defines specify the offset and size of the
4032	  environment area within the total memory of your EEPROM.
4033
4034	- CONFIG_SYS_I2C_EEPROM_ADDR:
4035	  If defined, specified the chip address of the EEPROM device.
4036	  The default address is zero.
4037
4038	- CONFIG_SYS_I2C_EEPROM_BUS:
4039	  If defined, specified the i2c bus of the EEPROM device.
4040
4041	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
4042	  If defined, the number of bits used to address bytes in a
4043	  single page in the EEPROM device.  A 64 byte page, for example
4044	  would require six bits.
4045
4046	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
4047	  If defined, the number of milliseconds to delay between
4048	  page writes.	The default is zero milliseconds.
4049
4050	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
4051	  The length in bytes of the EEPROM memory array address.  Note
4052	  that this is NOT the chip address length!
4053
4054	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
4055	  EEPROM chips that implement "address overflow" are ones
4056	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
4057	  address and the extra bits end up in the "chip address" bit
4058	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
4059	  byte chips.
4060
4061	  Note that we consider the length of the address field to
4062	  still be one byte because the extra address bits are hidden
4063	  in the chip address.
4064
4065	- CONFIG_SYS_EEPROM_SIZE:
4066	  The size in bytes of the EEPROM device.
4067
4068	- CONFIG_ENV_EEPROM_IS_ON_I2C
4069	  define this, if you have I2C and SPI activated, and your
4070	  EEPROM, which holds the environment, is on the I2C bus.
4071
4072	- CONFIG_I2C_ENV_EEPROM_BUS
4073	  if you have an Environment on an EEPROM reached over
4074	  I2C muxes, you can define here, how to reach this
4075	  EEPROM. For example:
4076
4077	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
4078
4079	  EEPROM which holds the environment, is reached over
4080	  a pca9547 i2c mux with address 0x70, channel 3.
4081
4082- CONFIG_ENV_IS_IN_DATAFLASH:
4083
4084	Define this if you have a DataFlash memory device which you
4085	want to use for the environment.
4086
4087	- CONFIG_ENV_OFFSET:
4088	- CONFIG_ENV_ADDR:
4089	- CONFIG_ENV_SIZE:
4090
4091	  These three #defines specify the offset and size of the
4092	  environment area within the total memory of your DataFlash placed
4093	  at the specified address.
4094
4095- CONFIG_ENV_IS_IN_SPI_FLASH:
4096
4097	Define this if you have a SPI Flash memory device which you
4098	want to use for the environment.
4099
4100	- CONFIG_ENV_OFFSET:
4101	- CONFIG_ENV_SIZE:
4102
4103	  These two #defines specify the offset and size of the
4104	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
4105	  aligned to an erase sector boundary.
4106
4107	- CONFIG_ENV_SECT_SIZE:
4108
4109	  Define the SPI flash's sector size.
4110
4111	- CONFIG_ENV_OFFSET_REDUND (optional):
4112
4113	  This setting describes a second storage area of CONFIG_ENV_SIZE
4114	  size used to hold a redundant copy of the environment data, so
4115	  that there is a valid backup copy in case there is a power failure
4116	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
4117	  aligned to an erase sector boundary.
4118
4119	- CONFIG_ENV_SPI_BUS (optional):
4120	- CONFIG_ENV_SPI_CS (optional):
4121
4122	  Define the SPI bus and chip select. If not defined they will be 0.
4123
4124	- CONFIG_ENV_SPI_MAX_HZ (optional):
4125
4126	  Define the SPI max work clock. If not defined then use 1MHz.
4127
4128	- CONFIG_ENV_SPI_MODE (optional):
4129
4130	  Define the SPI work mode. If not defined then use SPI_MODE_3.
4131
4132- CONFIG_ENV_IS_IN_REMOTE:
4133
4134	Define this if you have a remote memory space which you
4135	want to use for the local device's environment.
4136
4137	- CONFIG_ENV_ADDR:
4138	- CONFIG_ENV_SIZE:
4139
4140	  These two #defines specify the address and size of the
4141	  environment area within the remote memory space. The
4142	  local device can get the environment from remote memory
4143	  space by SRIO or PCIE links.
4144
4145BE CAREFUL! For some special cases, the local device can not use
4146"saveenv" command. For example, the local device will get the
4147environment stored in a remote NOR flash by SRIO or PCIE link,
4148but it can not erase, write this NOR flash by SRIO or PCIE interface.
4149
4150- CONFIG_ENV_IS_IN_NAND:
4151
4152	Define this if you have a NAND device which you want to use
4153	for the environment.
4154
4155	- CONFIG_ENV_OFFSET:
4156	- CONFIG_ENV_SIZE:
4157
4158	  These two #defines specify the offset and size of the environment
4159	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
4160	  aligned to an erase block boundary.
4161
4162	- CONFIG_ENV_OFFSET_REDUND (optional):
4163
4164	  This setting describes a second storage area of CONFIG_ENV_SIZE
4165	  size used to hold a redundant copy of the environment data, so
4166	  that there is a valid backup copy in case there is a power failure
4167	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
4168	  aligned to an erase block boundary.
4169
4170	- CONFIG_ENV_RANGE (optional):
4171
4172	  Specifies the length of the region in which the environment
4173	  can be written.  This should be a multiple of the NAND device's
4174	  block size.  Specifying a range with more erase blocks than
4175	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
4176	  the range to be avoided.
4177
4178	- CONFIG_ENV_OFFSET_OOB (optional):
4179
4180	  Enables support for dynamically retrieving the offset of the
4181	  environment from block zero's out-of-band data.  The
4182	  "nand env.oob" command can be used to record this offset.
4183	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
4184	  using CONFIG_ENV_OFFSET_OOB.
4185
4186- CONFIG_NAND_ENV_DST
4187
4188	Defines address in RAM to which the nand_spl code should copy the
4189	environment. If redundant environment is used, it will be copied to
4190	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
4191
4192- CONFIG_ENV_IS_IN_UBI:
4193
4194	Define this if you have an UBI volume that you want to use for the
4195	environment.  This has the benefit of wear-leveling the environment
4196	accesses, which is important on NAND.
4197
4198	- CONFIG_ENV_UBI_PART:
4199
4200	  Define this to a string that is the mtd partition containing the UBI.
4201
4202	- CONFIG_ENV_UBI_VOLUME:
4203
4204	  Define this to the name of the volume that you want to store the
4205	  environment in.
4206
4207	- CONFIG_ENV_UBI_VOLUME_REDUND:
4208
4209	  Define this to the name of another volume to store a second copy of
4210	  the environment in.  This will enable redundant environments in UBI.
4211	  It is assumed that both volumes are in the same MTD partition.
4212
4213	- CONFIG_UBI_SILENCE_MSG
4214	- CONFIG_UBIFS_SILENCE_MSG
4215
4216	  You will probably want to define these to avoid a really noisy system
4217	  when storing the env in UBI.
4218
4219- CONFIG_ENV_IS_IN_FAT:
4220       Define this if you want to use the FAT file system for the environment.
4221
4222       - FAT_ENV_INTERFACE:
4223
4224         Define this to a string that is the name of the block device.
4225
4226       - FAT_ENV_DEV_AND_PART:
4227
4228         Define this to a string to specify the partition of the device. It can
4229         be as following:
4230
4231           "D:P", "D:0", "D", "D:" or "D:auto" (D, P are integers. And P >= 1)
4232               - "D:P": device D partition P. Error occurs if device D has no
4233                        partition table.
4234               - "D:0": device D.
4235               - "D" or "D:": device D partition 1 if device D has partition
4236                              table, or the whole device D if has no partition
4237                              table.
4238               - "D:auto": first partition in device D with bootable flag set.
4239                           If none, first valid partition in device D. If no
4240                           partition table then means device D.
4241
4242       - FAT_ENV_FILE:
4243
4244         It's a string of the FAT file name. This file use to store the
4245         environment.
4246
4247       - CONFIG_FAT_WRITE:
4248         This should be defined. Otherwise it cannot save the environment file.
4249
4250- CONFIG_ENV_IS_IN_MMC:
4251
4252	Define this if you have an MMC device which you want to use for the
4253	environment.
4254
4255	- CONFIG_SYS_MMC_ENV_DEV:
4256
4257	  Specifies which MMC device the environment is stored in.
4258
4259	- CONFIG_SYS_MMC_ENV_PART (optional):
4260
4261	  Specifies which MMC partition the environment is stored in. If not
4262	  set, defaults to partition 0, the user area. Common values might be
4263	  1 (first MMC boot partition), 2 (second MMC boot partition).
4264
4265	- CONFIG_ENV_OFFSET:
4266	- CONFIG_ENV_SIZE:
4267
4268	  These two #defines specify the offset and size of the environment
4269	  area within the specified MMC device.
4270
4271	  If offset is positive (the usual case), it is treated as relative to
4272	  the start of the MMC partition. If offset is negative, it is treated
4273	  as relative to the end of the MMC partition. This can be useful if
4274	  your board may be fitted with different MMC devices, which have
4275	  different sizes for the MMC partitions, and you always want the
4276	  environment placed at the very end of the partition, to leave the
4277	  maximum possible space before it, to store other data.
4278
4279	  These two values are in units of bytes, but must be aligned to an
4280	  MMC sector boundary.
4281
4282	- CONFIG_ENV_OFFSET_REDUND (optional):
4283
4284	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
4285	  hold a redundant copy of the environment data. This provides a
4286	  valid backup copy in case the other copy is corrupted, e.g. due
4287	  to a power failure during a "saveenv" operation.
4288
4289	  This value may also be positive or negative; this is handled in the
4290	  same way as CONFIG_ENV_OFFSET.
4291
4292	  This value is also in units of bytes, but must also be aligned to
4293	  an MMC sector boundary.
4294
4295	- CONFIG_ENV_SIZE_REDUND (optional):
4296
4297	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
4298	  set. If this value is set, it must be set to the same value as
4299	  CONFIG_ENV_SIZE.
4300
4301- CONFIG_SYS_SPI_INIT_OFFSET
4302
4303	Defines offset to the initial SPI buffer area in DPRAM. The
4304	area is used at an early stage (ROM part) if the environment
4305	is configured to reside in the SPI EEPROM: We need a 520 byte
4306	scratch DPRAM area. It is used between the two initialization
4307	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
4308	to be a good choice since it makes it far enough from the
4309	start of the data area as well as from the stack pointer.
4310
4311Please note that the environment is read-only until the monitor
4312has been relocated to RAM and a RAM copy of the environment has been
4313created; also, when using EEPROM you will have to use getenv_f()
4314until then to read environment variables.
4315
4316The environment is protected by a CRC32 checksum. Before the monitor
4317is relocated into RAM, as a result of a bad CRC you will be working
4318with the compiled-in default environment - *silently*!!! [This is
4319necessary, because the first environment variable we need is the
4320"baudrate" setting for the console - if we have a bad CRC, we don't
4321have any device yet where we could complain.]
4322
4323Note: once the monitor has been relocated, then it will complain if
4324the default environment is used; a new CRC is computed as soon as you
4325use the "saveenv" command to store a valid environment.
4326
4327- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
4328		Echo the inverted Ethernet link state to the fault LED.
4329
4330		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
4331		      also needs to be defined.
4332
4333- CONFIG_SYS_FAULT_MII_ADDR:
4334		MII address of the PHY to check for the Ethernet link state.
4335
4336- CONFIG_NS16550_MIN_FUNCTIONS:
4337		Define this if you desire to only have use of the NS16550_init
4338		and NS16550_putc functions for the serial driver located at
4339		drivers/serial/ns16550.c.  This option is useful for saving
4340		space for already greatly restricted images, including but not
4341		limited to NAND_SPL configurations.
4342
4343- CONFIG_DISPLAY_BOARDINFO
4344		Display information about the board that U-Boot is running on
4345		when U-Boot starts up. The board function checkboard() is called
4346		to do this.
4347
4348- CONFIG_DISPLAY_BOARDINFO_LATE
4349		Similar to the previous option, but display this information
4350		later, once stdio is running and output goes to the LCD, if
4351		present.
4352
4353- CONFIG_BOARD_SIZE_LIMIT:
4354		Maximum size of the U-Boot image. When defined, the
4355		build system checks that the actual size does not
4356		exceed it.
4357
4358Low Level (hardware related) configuration options:
4359---------------------------------------------------
4360
4361- CONFIG_SYS_CACHELINE_SIZE:
4362		Cache Line Size of the CPU.
4363
4364- CONFIG_SYS_DEFAULT_IMMR:
4365		Default address of the IMMR after system reset.
4366
4367		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
4368		and RPXsuper) to be able to adjust the position of
4369		the IMMR register after a reset.
4370
4371- CONFIG_SYS_CCSRBAR_DEFAULT:
4372		Default (power-on reset) physical address of CCSR on Freescale
4373		PowerPC SOCs.
4374
4375- CONFIG_SYS_CCSRBAR:
4376		Virtual address of CCSR.  On a 32-bit build, this is typically
4377		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
4378
4379		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
4380		for cross-platform code that uses that macro instead.
4381
4382- CONFIG_SYS_CCSRBAR_PHYS:
4383		Physical address of CCSR.  CCSR can be relocated to a new
4384		physical address, if desired.  In this case, this macro should
4385		be set to that address.	 Otherwise, it should be set to the
4386		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
4387		is typically relocated on 36-bit builds.  It is recommended
4388		that this macro be defined via the _HIGH and _LOW macros:
4389
4390		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
4391			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
4392
4393- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
4394		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
4395		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
4396		used in assembly code, so it must not contain typecasts or
4397		integer size suffixes (e.g. "ULL").
4398
4399- CONFIG_SYS_CCSRBAR_PHYS_LOW:
4400		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
4401		used in assembly code, so it must not contain typecasts or
4402		integer size suffixes (e.g. "ULL").
4403
4404- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
4405		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
4406		forced to a value that ensures that CCSR is not relocated.
4407
4408- Floppy Disk Support:
4409		CONFIG_SYS_FDC_DRIVE_NUMBER
4410
4411		the default drive number (default value 0)
4412
4413		CONFIG_SYS_ISA_IO_STRIDE
4414
4415		defines the spacing between FDC chipset registers
4416		(default value 1)
4417
4418		CONFIG_SYS_ISA_IO_OFFSET
4419
4420		defines the offset of register from address. It
4421		depends on which part of the data bus is connected to
4422		the FDC chipset. (default value 0)
4423
4424		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4425		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4426		default value.
4427
4428		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4429		fdc_hw_init() is called at the beginning of the FDC
4430		setup. fdc_hw_init() must be provided by the board
4431		source code. It is used to make hardware-dependent
4432		initializations.
4433
4434- CONFIG_IDE_AHB:
4435		Most IDE controllers were designed to be connected with PCI
4436		interface. Only few of them were designed for AHB interface.
4437		When software is doing ATA command and data transfer to
4438		IDE devices through IDE-AHB controller, some additional
4439		registers accessing to these kind of IDE-AHB controller
4440		is required.
4441
4442- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4443		DO NOT CHANGE unless you know exactly what you're
4444		doing! (11-4) [MPC8xx/82xx systems only]
4445
4446- CONFIG_SYS_INIT_RAM_ADDR:
4447
4448		Start address of memory area that can be used for
4449		initial data and stack; please note that this must be
4450		writable memory that is working WITHOUT special
4451		initialization, i. e. you CANNOT use normal RAM which
4452		will become available only after programming the
4453		memory controller and running certain initialization
4454		sequences.
4455
4456		U-Boot uses the following memory types:
4457		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4458		- MPC824X: data cache
4459		- PPC4xx:  data cache
4460
4461- CONFIG_SYS_GBL_DATA_OFFSET:
4462
4463		Offset of the initial data structure in the memory
4464		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4465		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4466		data is located at the end of the available space
4467		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4468		GENERATED_GBL_DATA_SIZE), and the initial stack is just
4469		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4470		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4471
4472	Note:
4473		On the MPC824X (or other systems that use the data
4474		cache for initial memory) the address chosen for
4475		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4476		point to an otherwise UNUSED address space between
4477		the top of RAM and the start of the PCI space.
4478
4479- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4480
4481- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4482
4483- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4484
4485- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4486
4487- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4488
4489- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4490
4491- CONFIG_SYS_OR_TIMING_SDRAM:
4492		SDRAM timing
4493
4494- CONFIG_SYS_MAMR_PTA:
4495		periodic timer for refresh
4496
4497- CONFIG_SYS_DER:	Debug Event Register (37-47)
4498
4499- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4500  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4501  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4502  CONFIG_SYS_BR1_PRELIM:
4503		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4504
4505- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4506  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4507  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4508		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4509
4510- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4511  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4512		Machine Mode Register and Memory Periodic Timer
4513		Prescaler definitions (SDRAM timing)
4514
4515- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4516		enable I2C microcode relocation patch (MPC8xx);
4517		define relocation offset in DPRAM [DSP2]
4518
4519- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4520		enable SMC microcode relocation patch (MPC8xx);
4521		define relocation offset in DPRAM [SMC1]
4522
4523- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4524		enable SPI microcode relocation patch (MPC8xx);
4525		define relocation offset in DPRAM [SCC4]
4526
4527- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4528		Offset of the bootmode word in DPRAM used by post
4529		(Power On Self Tests). This definition overrides
4530		#define'd default value in commproc.h resp.
4531		cpm_8260.h.
4532
4533- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4534  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4535  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4536  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4537  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4538  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4539  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4540  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4541		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4542
4543- CONFIG_PCI_DISABLE_PCIE:
4544		Disable PCI-Express on systems where it is supported but not
4545		required.
4546
4547- CONFIG_PCI_ENUM_ONLY
4548		Only scan through and get the devices on the buses.
4549		Don't do any setup work, presumably because someone or
4550		something has already done it, and we don't need to do it
4551		a second time.	Useful for platforms that are pre-booted
4552		by coreboot or similar.
4553
4554- CONFIG_PCI_INDIRECT_BRIDGE:
4555		Enable support for indirect PCI bridges.
4556
4557- CONFIG_SYS_SRIO:
4558		Chip has SRIO or not
4559
4560- CONFIG_SRIO1:
4561		Board has SRIO 1 port available
4562
4563- CONFIG_SRIO2:
4564		Board has SRIO 2 port available
4565
4566- CONFIG_SRIO_PCIE_BOOT_MASTER
4567		Board can support master function for Boot from SRIO and PCIE
4568
4569- CONFIG_SYS_SRIOn_MEM_VIRT:
4570		Virtual Address of SRIO port 'n' memory region
4571
4572- CONFIG_SYS_SRIOn_MEM_PHYS:
4573		Physical Address of SRIO port 'n' memory region
4574
4575- CONFIG_SYS_SRIOn_MEM_SIZE:
4576		Size of SRIO port 'n' memory region
4577
4578- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4579		Defined to tell the NAND controller that the NAND chip is using
4580		a 16 bit bus.
4581		Not all NAND drivers use this symbol.
4582		Example of drivers that use it:
4583		- drivers/mtd/nand/ndfc.c
4584		- drivers/mtd/nand/mxc_nand.c
4585
4586- CONFIG_SYS_NDFC_EBC0_CFG
4587		Sets the EBC0_CFG register for the NDFC. If not defined
4588		a default value will be used.
4589
4590- CONFIG_SPD_EEPROM
4591		Get DDR timing information from an I2C EEPROM. Common
4592		with pluggable memory modules such as SODIMMs
4593
4594  SPD_EEPROM_ADDRESS
4595		I2C address of the SPD EEPROM
4596
4597- CONFIG_SYS_SPD_BUS_NUM
4598		If SPD EEPROM is on an I2C bus other than the first
4599		one, specify here. Note that the value must resolve
4600		to something your driver can deal with.
4601
4602- CONFIG_SYS_DDR_RAW_TIMING
4603		Get DDR timing information from other than SPD. Common with
4604		soldered DDR chips onboard without SPD. DDR raw timing
4605		parameters are extracted from datasheet and hard-coded into
4606		header files or board specific files.
4607
4608- CONFIG_FSL_DDR_INTERACTIVE
4609		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4610
4611- CONFIG_FSL_DDR_SYNC_REFRESH
4612		Enable sync of refresh for multiple controllers.
4613
4614- CONFIG_FSL_DDR_BIST
4615		Enable built-in memory test for Freescale DDR controllers.
4616
4617- CONFIG_SYS_83XX_DDR_USES_CS0
4618		Only for 83xx systems. If specified, then DDR should
4619		be configured using CS0 and CS1 instead of CS2 and CS3.
4620
4621- CONFIG_ETHER_ON_FEC[12]
4622		Define to enable FEC[12] on a 8xx series processor.
4623
4624- CONFIG_FEC[12]_PHY
4625		Define to the hardcoded PHY address which corresponds
4626		to the given FEC; i. e.
4627			#define CONFIG_FEC1_PHY 4
4628		means that the PHY with address 4 is connected to FEC1
4629
4630		When set to -1, means to probe for first available.
4631
4632- CONFIG_FEC[12]_PHY_NORXERR
4633		The PHY does not have a RXERR line (RMII only).
4634		(so program the FEC to ignore it).
4635
4636- CONFIG_RMII
4637		Enable RMII mode for all FECs.
4638		Note that this is a global option, we can't
4639		have one FEC in standard MII mode and another in RMII mode.
4640
4641- CONFIG_CRC32_VERIFY
4642		Add a verify option to the crc32 command.
4643		The syntax is:
4644
4645		=> crc32 -v <address> <count> <crc32>
4646
4647		Where address/count indicate a memory area
4648		and crc32 is the correct crc32 which the
4649		area should have.
4650
4651- CONFIG_LOOPW
4652		Add the "loopw" memory command. This only takes effect if
4653		the memory commands are activated globally (CONFIG_CMD_MEM).
4654
4655- CONFIG_MX_CYCLIC
4656		Add the "mdc" and "mwc" memory commands. These are cyclic
4657		"md/mw" commands.
4658		Examples:
4659
4660		=> mdc.b 10 4 500
4661		This command will print 4 bytes (10,11,12,13) each 500 ms.
4662
4663		=> mwc.l 100 12345678 10
4664		This command will write 12345678 to address 100 all 10 ms.
4665
4666		This only takes effect if the memory commands are activated
4667		globally (CONFIG_CMD_MEM).
4668
4669- CONFIG_SKIP_LOWLEVEL_INIT
4670		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4671		low level initializations (like setting up the memory
4672		controller) are omitted and/or U-Boot does not
4673		relocate itself into RAM.
4674
4675		Normally this variable MUST NOT be defined. The only
4676		exception is when U-Boot is loaded (to RAM) by some
4677		other boot loader or by a debugger which performs
4678		these initializations itself.
4679
4680- CONFIG_SKIP_LOWLEVEL_INIT_ONLY
4681		[ARM926EJ-S only] This allows just the call to lowlevel_init()
4682		to be skipped. The normal CP15 init (such as enabling the
4683		instruction cache) is still performed.
4684
4685- CONFIG_SPL_BUILD
4686		Modifies the behaviour of start.S when compiling a loader
4687		that is executed before the actual U-Boot. E.g. when
4688		compiling a NAND SPL.
4689
4690- CONFIG_TPL_BUILD
4691		Modifies the behaviour of start.S  when compiling a loader
4692		that is executed after the SPL and before the actual U-Boot.
4693		It is loaded by the SPL.
4694
4695- CONFIG_SYS_MPC85XX_NO_RESETVEC
4696		Only for 85xx systems. If this variable is specified, the section
4697		.resetvec is not kept and the section .bootpg is placed in the
4698		previous 4k of the .text section.
4699
4700- CONFIG_ARCH_MAP_SYSMEM
4701		Generally U-Boot (and in particular the md command) uses
4702		effective address. It is therefore not necessary to regard
4703		U-Boot address as virtual addresses that need to be translated
4704		to physical addresses. However, sandbox requires this, since
4705		it maintains its own little RAM buffer which contains all
4706		addressable memory. This option causes some memory accesses
4707		to be mapped through map_sysmem() / unmap_sysmem().
4708
4709- CONFIG_USE_ARCH_MEMCPY
4710  CONFIG_USE_ARCH_MEMSET
4711		If these options are used a optimized version of memcpy/memset will
4712		be used if available. These functions may be faster under some
4713		conditions but may increase the binary size.
4714
4715- CONFIG_X86_RESET_VECTOR
4716		If defined, the x86 reset vector code is included. This is not
4717		needed when U-Boot is running from Coreboot.
4718
4719- CONFIG_SYS_MPUCLK
4720		Defines the MPU clock speed (in MHz).
4721
4722		NOTE : currently only supported on AM335x platforms.
4723
4724- CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC:
4725		Enables the RTC32K OSC on AM33xx based plattforms
4726
4727- CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
4728		Option to disable subpage write in NAND driver
4729		driver that uses this:
4730		drivers/mtd/nand/davinci_nand.c
4731
4732Freescale QE/FMAN Firmware Support:
4733-----------------------------------
4734
4735The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4736loading of "firmware", which is encoded in the QE firmware binary format.
4737This firmware often needs to be loaded during U-Boot booting, so macros
4738are used to identify the storage device (NOR flash, SPI, etc) and the address
4739within that device.
4740
4741- CONFIG_SYS_FMAN_FW_ADDR
4742	The address in the storage device where the FMAN microcode is located.  The
4743	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4744	is also specified.
4745
4746- CONFIG_SYS_QE_FW_ADDR
4747	The address in the storage device where the QE microcode is located.  The
4748	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4749	is also specified.
4750
4751- CONFIG_SYS_QE_FMAN_FW_LENGTH
4752	The maximum possible size of the firmware.  The firmware binary format
4753	has a field that specifies the actual size of the firmware, but it
4754	might not be possible to read any part of the firmware unless some
4755	local storage is allocated to hold the entire firmware first.
4756
4757- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4758	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4759	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4760	virtual address in NOR flash.
4761
4762- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4763	Specifies that QE/FMAN firmware is located in NAND flash.
4764	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4765
4766- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4767	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4768	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4769
4770- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4771	Specifies that QE/FMAN firmware is located in the remote (master)
4772	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4773	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4774	window->master inbound window->master LAW->the ucode address in
4775	master's memory space.
4776
4777Freescale Layerscape Management Complex Firmware Support:
4778---------------------------------------------------------
4779The Freescale Layerscape Management Complex (MC) supports the loading of
4780"firmware".
4781This firmware often needs to be loaded during U-Boot booting, so macros
4782are used to identify the storage device (NOR flash, SPI, etc) and the address
4783within that device.
4784
4785- CONFIG_FSL_MC_ENET
4786	Enable the MC driver for Layerscape SoCs.
4787
4788Freescale Layerscape Debug Server Support:
4789-------------------------------------------
4790The Freescale Layerscape Debug Server Support supports the loading of
4791"Debug Server firmware" and triggering SP boot-rom.
4792This firmware often needs to be loaded during U-Boot booting.
4793
4794- CONFIG_SYS_MC_RSV_MEM_ALIGN
4795	Define alignment of reserved memory MC requires
4796
4797Reproducible builds
4798-------------------
4799
4800In order to achieve reproducible builds, timestamps used in the U-Boot build
4801process have to be set to a fixed value.
4802
4803This is done using the SOURCE_DATE_EPOCH environment variable.
4804SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
4805option for U-Boot or an environment variable in U-Boot.
4806
4807SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
4808
4809Building the Software:
4810======================
4811
4812Building U-Boot has been tested in several native build environments
4813and in many different cross environments. Of course we cannot support
4814all possibly existing versions of cross development tools in all
4815(potentially obsolete) versions. In case of tool chain problems we
4816recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4817which is extensively used to build and test U-Boot.
4818
4819If you are not using a native environment, it is assumed that you
4820have GNU cross compiling tools available in your path. In this case,
4821you must set the environment variable CROSS_COMPILE in your shell.
4822Note that no changes to the Makefile or any other source files are
4823necessary. For example using the ELDK on a 4xx CPU, please enter:
4824
4825	$ CROSS_COMPILE=ppc_4xx-
4826	$ export CROSS_COMPILE
4827
4828Note: If you wish to generate Windows versions of the utilities in
4829      the tools directory you can use the MinGW toolchain
4830      (http://www.mingw.org).  Set your HOST tools to the MinGW
4831      toolchain and execute 'make tools'.  For example:
4832
4833       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4834
4835      Binaries such as tools/mkimage.exe will be created which can
4836      be executed on computers running Windows.
4837
4838U-Boot is intended to be simple to build. After installing the
4839sources you must configure U-Boot for one specific board type. This
4840is done by typing:
4841
4842	make NAME_defconfig
4843
4844where "NAME_defconfig" is the name of one of the existing configu-
4845rations; see boards.cfg for supported names.
4846
4847Note: for some board special configuration names may exist; check if
4848      additional information is available from the board vendor; for
4849      instance, the TQM823L systems are available without (standard)
4850      or with LCD support. You can select such additional "features"
4851      when choosing the configuration, i. e.
4852
4853      make TQM823L_defconfig
4854	- will configure for a plain TQM823L, i. e. no LCD support
4855
4856      make TQM823L_LCD_defconfig
4857	- will configure for a TQM823L with U-Boot console on LCD
4858
4859      etc.
4860
4861
4862Finally, type "make all", and you should get some working U-Boot
4863images ready for download to / installation on your system:
4864
4865- "u-boot.bin" is a raw binary image
4866- "u-boot" is an image in ELF binary format
4867- "u-boot.srec" is in Motorola S-Record format
4868
4869By default the build is performed locally and the objects are saved
4870in the source directory. One of the two methods can be used to change
4871this behavior and build U-Boot to some external directory:
4872
48731. Add O= to the make command line invocations:
4874
4875	make O=/tmp/build distclean
4876	make O=/tmp/build NAME_defconfig
4877	make O=/tmp/build all
4878
48792. Set environment variable KBUILD_OUTPUT to point to the desired location:
4880
4881	export KBUILD_OUTPUT=/tmp/build
4882	make distclean
4883	make NAME_defconfig
4884	make all
4885
4886Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
4887variable.
4888
4889
4890Please be aware that the Makefiles assume you are using GNU make, so
4891for instance on NetBSD you might need to use "gmake" instead of
4892native "make".
4893
4894
4895If the system board that you have is not listed, then you will need
4896to port U-Boot to your hardware platform. To do this, follow these
4897steps:
4898
48991.  Create a new directory to hold your board specific code. Add any
4900    files you need. In your board directory, you will need at least
4901    the "Makefile" and a "<board>.c".
49022.  Create a new configuration file "include/configs/<board>.h" for
4903    your board.
49043.  If you're porting U-Boot to a new CPU, then also create a new
4905    directory to hold your CPU specific code. Add any files you need.
49064.  Run "make <board>_defconfig" with your new name.
49075.  Type "make", and you should get a working "u-boot.srec" file
4908    to be installed on your target system.
49096.  Debug and solve any problems that might arise.
4910    [Of course, this last step is much harder than it sounds.]
4911
4912
4913Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4914==============================================================
4915
4916If you have modified U-Boot sources (for instance added a new board
4917or support for new devices, a new CPU, etc.) you are expected to
4918provide feedback to the other developers. The feedback normally takes
4919the form of a "patch", i. e. a context diff against a certain (latest
4920official or latest in the git repository) version of U-Boot sources.
4921
4922But before you submit such a patch, please verify that your modifi-
4923cation did not break existing code. At least make sure that *ALL* of
4924the supported boards compile WITHOUT ANY compiler warnings. To do so,
4925just run the buildman script (tools/buildman/buildman), which will
4926configure and build U-Boot for ALL supported system. Be warned, this
4927will take a while. Please see the buildman README, or run 'buildman -H'
4928for documentation.
4929
4930
4931See also "U-Boot Porting Guide" below.
4932
4933
4934Monitor Commands - Overview:
4935============================
4936
4937go	- start application at address 'addr'
4938run	- run commands in an environment variable
4939bootm	- boot application image from memory
4940bootp	- boot image via network using BootP/TFTP protocol
4941bootz   - boot zImage from memory
4942tftpboot- boot image via network using TFTP protocol
4943	       and env variables "ipaddr" and "serverip"
4944	       (and eventually "gatewayip")
4945tftpput - upload a file via network using TFTP protocol
4946rarpboot- boot image via network using RARP/TFTP protocol
4947diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4948loads	- load S-Record file over serial line
4949loadb	- load binary file over serial line (kermit mode)
4950md	- memory display
4951mm	- memory modify (auto-incrementing)
4952nm	- memory modify (constant address)
4953mw	- memory write (fill)
4954cp	- memory copy
4955cmp	- memory compare
4956crc32	- checksum calculation
4957i2c	- I2C sub-system
4958sspi	- SPI utility commands
4959base	- print or set address offset
4960printenv- print environment variables
4961setenv	- set environment variables
4962saveenv - save environment variables to persistent storage
4963protect - enable or disable FLASH write protection
4964erase	- erase FLASH memory
4965flinfo	- print FLASH memory information
4966nand	- NAND memory operations (see doc/README.nand)
4967bdinfo	- print Board Info structure
4968iminfo	- print header information for application image
4969coninfo - print console devices and informations
4970ide	- IDE sub-system
4971loop	- infinite loop on address range
4972loopw	- infinite write loop on address range
4973mtest	- simple RAM test
4974icache	- enable or disable instruction cache
4975dcache	- enable or disable data cache
4976reset	- Perform RESET of the CPU
4977echo	- echo args to console
4978version - print monitor version
4979help	- print online help
4980?	- alias for 'help'
4981
4982
4983Monitor Commands - Detailed Description:
4984========================================
4985
4986TODO.
4987
4988For now: just type "help <command>".
4989
4990
4991Environment Variables:
4992======================
4993
4994U-Boot supports user configuration using Environment Variables which
4995can be made persistent by saving to Flash memory.
4996
4997Environment Variables are set using "setenv", printed using
4998"printenv", and saved to Flash using "saveenv". Using "setenv"
4999without a value can be used to delete a variable from the
5000environment. As long as you don't save the environment you are
5001working with an in-memory copy. In case the Flash area containing the
5002environment is erased by accident, a default environment is provided.
5003
5004Some configuration options can be set using Environment Variables.
5005
5006List of environment variables (most likely not complete):
5007
5008  baudrate	- see CONFIG_BAUDRATE
5009
5010  bootdelay	- see CONFIG_BOOTDELAY
5011
5012  bootcmd	- see CONFIG_BOOTCOMMAND
5013
5014  bootargs	- Boot arguments when booting an RTOS image
5015
5016  bootfile	- Name of the image to load with TFTP
5017
5018  bootm_low	- Memory range available for image processing in the bootm
5019		  command can be restricted. This variable is given as
5020		  a hexadecimal number and defines lowest address allowed
5021		  for use by the bootm command. See also "bootm_size"
5022		  environment variable. Address defined by "bootm_low" is
5023		  also the base of the initial memory mapping for the Linux
5024		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
5025		  bootm_mapsize.
5026
5027  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
5028		  This variable is given as a hexadecimal number and it
5029		  defines the size of the memory region starting at base
5030		  address bootm_low that is accessible by the Linux kernel
5031		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
5032		  as the default value if it is defined, and bootm_size is
5033		  used otherwise.
5034
5035  bootm_size	- 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 the size of the region
5038		  allowed for use by the bootm command. See also "bootm_low"
5039		  environment variable.
5040
5041  updatefile	- Location of the software update file on a TFTP server, used
5042		  by the automatic software update feature. Please refer to
5043		  documentation in doc/README.update for more details.
5044
5045  autoload	- if set to "no" (any string beginning with 'n'),
5046		  "bootp" will just load perform a lookup of the
5047		  configuration from the BOOTP server, but not try to
5048		  load any image using TFTP
5049
5050  autostart	- if set to "yes", an image loaded using the "bootp",
5051		  "rarpboot", "tftpboot" or "diskboot" commands will
5052		  be automatically started (by internally calling
5053		  "bootm")
5054
5055		  If set to "no", a standalone image passed to the
5056		  "bootm" command will be copied to the load address
5057		  (and eventually uncompressed), but NOT be started.
5058		  This can be used to load and uncompress arbitrary
5059		  data.
5060
5061  fdt_high	- if set this restricts the maximum address that the
5062		  flattened device tree will be copied into upon boot.
5063		  For example, if you have a system with 1 GB memory
5064		  at physical address 0x10000000, while Linux kernel
5065		  only recognizes the first 704 MB as low memory, you
5066		  may need to set fdt_high as 0x3C000000 to have the
5067		  device tree blob be copied to the maximum address
5068		  of the 704 MB low memory, so that Linux kernel can
5069		  access it during the boot procedure.
5070
5071		  If this is set to the special value 0xFFFFFFFF then
5072		  the fdt will not be copied at all on boot.  For this
5073		  to work it must reside in writable memory, have
5074		  sufficient padding on the end of it for u-boot to
5075		  add the information it needs into it, and the memory
5076		  must be accessible by the kernel.
5077
5078  fdtcontroladdr- if set this is the address of the control flattened
5079		  device tree used by U-Boot when CONFIG_OF_CONTROL is
5080		  defined.
5081
5082  i2cfast	- (PPC405GP|PPC405EP only)
5083		  if set to 'y' configures Linux I2C driver for fast
5084		  mode (400kHZ). This environment variable is used in
5085		  initialization code. So, for changes to be effective
5086		  it must be saved and board must be reset.
5087
5088  initrd_high	- restrict positioning of initrd images:
5089		  If this variable is not set, initrd images will be
5090		  copied to the highest possible address in RAM; this
5091		  is usually what you want since it allows for
5092		  maximum initrd size. If for some reason you want to
5093		  make sure that the initrd image is loaded below the
5094		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
5095		  variable to a value of "no" or "off" or "0".
5096		  Alternatively, you can set it to a maximum upper
5097		  address to use (U-Boot will still check that it
5098		  does not overwrite the U-Boot stack and data).
5099
5100		  For instance, when you have a system with 16 MB
5101		  RAM, and want to reserve 4 MB from use by Linux,
5102		  you can do this by adding "mem=12M" to the value of
5103		  the "bootargs" variable. However, now you must make
5104		  sure that the initrd image is placed in the first
5105		  12 MB as well - this can be done with
5106
5107		  setenv initrd_high 00c00000
5108
5109		  If you set initrd_high to 0xFFFFFFFF, this is an
5110		  indication to U-Boot that all addresses are legal
5111		  for the Linux kernel, including addresses in flash
5112		  memory. In this case U-Boot will NOT COPY the
5113		  ramdisk at all. This may be useful to reduce the
5114		  boot time on your system, but requires that this
5115		  feature is supported by your Linux kernel.
5116
5117  ipaddr	- IP address; needed for tftpboot command
5118
5119  loadaddr	- Default load address for commands like "bootp",
5120		  "rarpboot", "tftpboot", "loadb" or "diskboot"
5121
5122  loads_echo	- see CONFIG_LOADS_ECHO
5123
5124  serverip	- TFTP server IP address; needed for tftpboot command
5125
5126  bootretry	- see CONFIG_BOOT_RETRY_TIME
5127
5128  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
5129
5130  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
5131
5132  ethprime	- controls which interface is used first.
5133
5134  ethact	- controls which interface is currently active.
5135		  For example you can do the following
5136
5137		  => setenv ethact FEC
5138		  => ping 192.168.0.1 # traffic sent on FEC
5139		  => setenv ethact SCC
5140		  => ping 10.0.0.1 # traffic sent on SCC
5141
5142  ethrotate	- When set to "no" U-Boot does not go through all
5143		  available network interfaces.
5144		  It just stays at the currently selected interface.
5145
5146  netretry	- When set to "no" each network operation will
5147		  either succeed or fail without retrying.
5148		  When set to "once" the network operation will
5149		  fail when all the available network interfaces
5150		  are tried once without success.
5151		  Useful on scripts which control the retry operation
5152		  themselves.
5153
5154  npe_ucode	- set load address for the NPE microcode
5155
5156  silent_linux  - If set then Linux will be told to boot silently, by
5157		  changing the console to be empty. If "yes" it will be
5158		  made silent. If "no" it will not be made silent. If
5159		  unset, then it will be made silent if the U-Boot console
5160		  is silent.
5161
5162  tftpsrcp	- If this is set, the value is used for TFTP's
5163		  UDP source port.
5164
5165  tftpdstp	- If this is set, the value is used for TFTP's UDP
5166		  destination port instead of the Well Know Port 69.
5167
5168  tftpblocksize - Block size to use for TFTP transfers; if not set,
5169		  we use the TFTP server's default block size
5170
5171  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
5172		  seconds, minimum value is 1000 = 1 second). Defines
5173		  when a packet is considered to be lost so it has to
5174		  be retransmitted. The default is 5000 = 5 seconds.
5175		  Lowering this value may make downloads succeed
5176		  faster in networks with high packet loss rates or
5177		  with unreliable TFTP servers.
5178
5179  tftptimeoutcountmax	- maximum count of TFTP timeouts (no
5180		  unit, minimum value = 0). Defines how many timeouts
5181		  can happen during a single file transfer before that
5182		  transfer is aborted. The default is 10, and 0 means
5183		  'no timeouts allowed'. Increasing this value may help
5184		  downloads succeed with high packet loss rates, or with
5185		  unreliable TFTP servers or client hardware.
5186
5187  vlan		- When set to a value < 4095 the traffic over
5188		  Ethernet is encapsulated/received over 802.1q
5189		  VLAN tagged frames.
5190
5191  bootpretryperiod	- Period during which BOOTP/DHCP sends retries.
5192		  Unsigned value, in milliseconds. If not set, the period will
5193		  be either the default (28000), or a value based on
5194		  CONFIG_NET_RETRY_COUNT, if defined. This value has
5195		  precedence over the valu based on CONFIG_NET_RETRY_COUNT.
5196
5197The following image location variables contain the location of images
5198used in booting. The "Image" column gives the role of the image and is
5199not an environment variable name. The other columns are environment
5200variable names. "File Name" gives the name of the file on a TFTP
5201server, "RAM Address" gives the location in RAM the image will be
5202loaded to, and "Flash Location" gives the image's address in NOR
5203flash or offset in NAND flash.
5204
5205*Note* - these variables don't have to be defined for all boards, some
5206boards currently use other variables for these purposes, and some
5207boards use these variables for other purposes.
5208
5209Image		    File Name	     RAM Address       Flash Location
5210-----		    ---------	     -----------       --------------
5211u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
5212Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
5213device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
5214ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
5215
5216The following environment variables may be used and automatically
5217updated by the network boot commands ("bootp" and "rarpboot"),
5218depending the information provided by your boot server:
5219
5220  bootfile	- see above
5221  dnsip		- IP address of your Domain Name Server
5222  dnsip2	- IP address of your secondary Domain Name Server
5223  gatewayip	- IP address of the Gateway (Router) to use
5224  hostname	- Target hostname
5225  ipaddr	- see above
5226  netmask	- Subnet Mask
5227  rootpath	- Pathname of the root filesystem on the NFS server
5228  serverip	- see above
5229
5230
5231There are two special Environment Variables:
5232
5233  serial#	- contains hardware identification information such
5234		  as type string and/or serial number
5235  ethaddr	- Ethernet address
5236
5237These variables can be set only once (usually during manufacturing of
5238the board). U-Boot refuses to delete or overwrite these variables
5239once they have been set once.
5240
5241
5242Further special Environment Variables:
5243
5244  ver		- Contains the U-Boot version string as printed
5245		  with the "version" command. This variable is
5246		  readonly (see CONFIG_VERSION_VARIABLE).
5247
5248
5249Please note that changes to some configuration parameters may take
5250only effect after the next boot (yes, that's just like Windoze :-).
5251
5252
5253Callback functions for environment variables:
5254---------------------------------------------
5255
5256For some environment variables, the behavior of u-boot needs to change
5257when their values are changed.  This functionality allows functions to
5258be associated with arbitrary variables.  On creation, overwrite, or
5259deletion, the callback will provide the opportunity for some side
5260effect to happen or for the change to be rejected.
5261
5262The callbacks are named and associated with a function using the
5263U_BOOT_ENV_CALLBACK macro in your board or driver code.
5264
5265These callbacks are associated with variables in one of two ways.  The
5266static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
5267in the board configuration to a string that defines a list of
5268associations.  The list must be in the following format:
5269
5270	entry = variable_name[:callback_name]
5271	list = entry[,list]
5272
5273If the callback name is not specified, then the callback is deleted.
5274Spaces are also allowed anywhere in the list.
5275
5276Callbacks can also be associated by defining the ".callbacks" variable
5277with the same list format above.  Any association in ".callbacks" will
5278override any association in the static list. You can define
5279CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
5280".callbacks" environment variable in the default or embedded environment.
5281
5282If CONFIG_REGEX is defined, the variable_name above is evaluated as a
5283regular expression. This allows multiple variables to be connected to
5284the same callback without explicitly listing them all out.
5285
5286
5287Command Line Parsing:
5288=====================
5289
5290There are two different command line parsers available with U-Boot:
5291the old "simple" one, and the much more powerful "hush" shell:
5292
5293Old, simple command line parser:
5294--------------------------------
5295
5296- supports environment variables (through setenv / saveenv commands)
5297- several commands on one line, separated by ';'
5298- variable substitution using "... ${name} ..." syntax
5299- special characters ('$', ';') can be escaped by prefixing with '\',
5300  for example:
5301	setenv bootcmd bootm \${address}
5302- You can also escape text by enclosing in single apostrophes, for example:
5303	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
5304
5305Hush shell:
5306-----------
5307
5308- similar to Bourne shell, with control structures like
5309  if...then...else...fi, for...do...done; while...do...done,
5310  until...do...done, ...
5311- supports environment ("global") variables (through setenv / saveenv
5312  commands) and local shell variables (through standard shell syntax
5313  "name=value"); only environment variables can be used with "run"
5314  command
5315
5316General rules:
5317--------------
5318
5319(1) If a command line (or an environment variable executed by a "run"
5320    command) contains several commands separated by semicolon, and
5321    one of these commands fails, then the remaining commands will be
5322    executed anyway.
5323
5324(2) If you execute several variables with one call to run (i. e.
5325    calling run with a list of variables as arguments), any failing
5326    command will cause "run" to terminate, i. e. the remaining
5327    variables are not executed.
5328
5329Note for Redundant Ethernet Interfaces:
5330=======================================
5331
5332Some boards come with redundant Ethernet interfaces; U-Boot supports
5333such configurations and is capable of automatic selection of a
5334"working" interface when needed. MAC assignment works as follows:
5335
5336Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
5337MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
5338"eth1addr" (=>eth1), "eth2addr", ...
5339
5340If the network interface stores some valid MAC address (for instance
5341in SROM), this is used as default address if there is NO correspon-
5342ding setting in the environment; if the corresponding environment
5343variable is set, this overrides the settings in the card; that means:
5344
5345o If the SROM has a valid MAC address, and there is no address in the
5346  environment, the SROM's address is used.
5347
5348o If there is no valid address in the SROM, and a definition in the
5349  environment exists, then the value from the environment variable is
5350  used.
5351
5352o If both the SROM and the environment contain a MAC address, and
5353  both addresses are the same, this MAC address is used.
5354
5355o If both the SROM and the environment contain a MAC address, and the
5356  addresses differ, the value from the environment is used and a
5357  warning is printed.
5358
5359o If neither SROM nor the environment contain a MAC address, an error
5360  is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
5361  a random, locally-assigned MAC is used.
5362
5363If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
5364will be programmed into hardware as part of the initialization process.	 This
5365may be skipped by setting the appropriate 'ethmacskip' environment variable.
5366The naming convention is as follows:
5367"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
5368
5369Image Formats:
5370==============
5371
5372U-Boot is capable of booting (and performing other auxiliary operations on)
5373images in two formats:
5374
5375New uImage format (FIT)
5376-----------------------
5377
5378Flexible and powerful format based on Flattened Image Tree -- FIT (similar
5379to Flattened Device Tree). It allows the use of images with multiple
5380components (several kernels, ramdisks, etc.), with contents protected by
5381SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
5382
5383
5384Old uImage format
5385-----------------
5386
5387Old image format is based on binary files which can be basically anything,
5388preceded by a special header; see the definitions in include/image.h for
5389details; basically, the header defines the following image properties:
5390
5391* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
5392  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
5393  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
5394  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
5395  INTEGRITY).
5396* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
5397  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
5398  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
5399* Compression Type (uncompressed, gzip, bzip2)
5400* Load Address
5401* Entry Point
5402* Image Name
5403* Image Timestamp
5404
5405The header is marked by a special Magic Number, and both the header
5406and the data portions of the image are secured against corruption by
5407CRC32 checksums.
5408
5409
5410Linux Support:
5411==============
5412
5413Although U-Boot should support any OS or standalone application
5414easily, the main focus has always been on Linux during the design of
5415U-Boot.
5416
5417U-Boot includes many features that so far have been part of some
5418special "boot loader" code within the Linux kernel. Also, any
5419"initrd" images to be used are no longer part of one big Linux image;
5420instead, kernel and "initrd" are separate images. This implementation
5421serves several purposes:
5422
5423- the same features can be used for other OS or standalone
5424  applications (for instance: using compressed images to reduce the
5425  Flash memory footprint)
5426
5427- it becomes much easier to port new Linux kernel versions because
5428  lots of low-level, hardware dependent stuff are done by U-Boot
5429
5430- the same Linux kernel image can now be used with different "initrd"
5431  images; of course this also means that different kernel images can
5432  be run with the same "initrd". This makes testing easier (you don't
5433  have to build a new "zImage.initrd" Linux image when you just
5434  change a file in your "initrd"). Also, a field-upgrade of the
5435  software is easier now.
5436
5437
5438Linux HOWTO:
5439============
5440
5441Porting Linux to U-Boot based systems:
5442---------------------------------------
5443
5444U-Boot cannot save you from doing all the necessary modifications to
5445configure the Linux device drivers for use with your target hardware
5446(no, we don't intend to provide a full virtual machine interface to
5447Linux :-).
5448
5449But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
5450
5451Just make sure your machine specific header file (for instance
5452include/asm-ppc/tqm8xx.h) includes the same definition of the Board
5453Information structure as we define in include/asm-<arch>/u-boot.h,
5454and make sure that your definition of IMAP_ADDR uses the same value
5455as your U-Boot configuration in CONFIG_SYS_IMMR.
5456
5457Note that U-Boot now has a driver model, a unified model for drivers.
5458If you are adding a new driver, plumb it into driver model. If there
5459is no uclass available, you are encouraged to create one. See
5460doc/driver-model.
5461
5462
5463Configuring the Linux kernel:
5464-----------------------------
5465
5466No specific requirements for U-Boot. Make sure you have some root
5467device (initial ramdisk, NFS) for your target system.
5468
5469
5470Building a Linux Image:
5471-----------------------
5472
5473With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5474not used. If you use recent kernel source, a new build target
5475"uImage" will exist which automatically builds an image usable by
5476U-Boot. Most older kernels also have support for a "pImage" target,
5477which was introduced for our predecessor project PPCBoot and uses a
5478100% compatible format.
5479
5480Example:
5481
5482	make TQM850L_defconfig
5483	make oldconfig
5484	make dep
5485	make uImage
5486
5487The "uImage" build target uses a special tool (in 'tools/mkimage') to
5488encapsulate a compressed Linux kernel image with header	 information,
5489CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5490
5491* build a standard "vmlinux" kernel image (in ELF binary format):
5492
5493* convert the kernel into a raw binary image:
5494
5495	${CROSS_COMPILE}-objcopy -O binary \
5496				 -R .note -R .comment \
5497				 -S vmlinux linux.bin
5498
5499* compress the binary image:
5500
5501	gzip -9 linux.bin
5502
5503* package compressed binary image for U-Boot:
5504
5505	mkimage -A ppc -O linux -T kernel -C gzip \
5506		-a 0 -e 0 -n "Linux Kernel Image" \
5507		-d linux.bin.gz uImage
5508
5509
5510The "mkimage" tool can also be used to create ramdisk images for use
5511with U-Boot, either separated from the Linux kernel image, or
5512combined into one file. "mkimage" encapsulates the images with a 64
5513byte header containing information about target architecture,
5514operating system, image type, compression method, entry points, time
5515stamp, CRC32 checksums, etc.
5516
5517"mkimage" can be called in two ways: to verify existing images and
5518print the header information, or to build new images.
5519
5520In the first form (with "-l" option) mkimage lists the information
5521contained in the header of an existing U-Boot image; this includes
5522checksum verification:
5523
5524	tools/mkimage -l image
5525	  -l ==> list image header information
5526
5527The second form (with "-d" option) is used to build a U-Boot image
5528from a "data file" which is used as image payload:
5529
5530	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5531		      -n name -d data_file image
5532	  -A ==> set architecture to 'arch'
5533	  -O ==> set operating system to 'os'
5534	  -T ==> set image type to 'type'
5535	  -C ==> set compression type 'comp'
5536	  -a ==> set load address to 'addr' (hex)
5537	  -e ==> set entry point to 'ep' (hex)
5538	  -n ==> set image name to 'name'
5539	  -d ==> use image data from 'datafile'
5540
5541Right now, all Linux kernels for PowerPC systems use the same load
5542address (0x00000000), but the entry point address depends on the
5543kernel version:
5544
5545- 2.2.x kernels have the entry point at 0x0000000C,
5546- 2.3.x and later kernels have the entry point at 0x00000000.
5547
5548So a typical call to build a U-Boot image would read:
5549
5550	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5551	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5552	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5553	> examples/uImage.TQM850L
5554	Image Name:   2.4.4 kernel for TQM850L
5555	Created:      Wed Jul 19 02:34:59 2000
5556	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5557	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5558	Load Address: 0x00000000
5559	Entry Point:  0x00000000
5560
5561To verify the contents of the image (or check for corruption):
5562
5563	-> tools/mkimage -l examples/uImage.TQM850L
5564	Image Name:   2.4.4 kernel for TQM850L
5565	Created:      Wed Jul 19 02:34:59 2000
5566	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5567	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5568	Load Address: 0x00000000
5569	Entry Point:  0x00000000
5570
5571NOTE: for embedded systems where boot time is critical you can trade
5572speed for memory and install an UNCOMPRESSED image instead: this
5573needs more space in Flash, but boots much faster since it does not
5574need to be uncompressed:
5575
5576	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5577	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5578	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5579	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5580	> examples/uImage.TQM850L-uncompressed
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 (uncompressed)
5584	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5585	Load Address: 0x00000000
5586	Entry Point:  0x00000000
5587
5588
5589Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5590when your kernel is intended to use an initial ramdisk:
5591
5592	-> tools/mkimage -n 'Simple Ramdisk Image' \
5593	> -A ppc -O linux -T ramdisk -C gzip \
5594	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5595	Image Name:   Simple Ramdisk Image
5596	Created:      Wed Jan 12 14:01:50 2000
5597	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5598	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5599	Load Address: 0x00000000
5600	Entry Point:  0x00000000
5601
5602The "dumpimage" is a tool to disassemble images built by mkimage. Its "-i"
5603option performs the converse operation of the mkimage's second form (the "-d"
5604option). Given an image built by mkimage, the dumpimage extracts a "data file"
5605from the image:
5606
5607	tools/dumpimage -i image -T type -p position data_file
5608	  -i ==> extract from the 'image' a specific 'data_file'
5609	  -T ==> set image type to 'type'
5610	  -p ==> 'position' (starting at 0) of the 'data_file' inside the 'image'
5611
5612
5613Installing a Linux Image:
5614-------------------------
5615
5616To downloading a U-Boot image over the serial (console) interface,
5617you must convert the image to S-Record format:
5618
5619	objcopy -I binary -O srec examples/image examples/image.srec
5620
5621The 'objcopy' does not understand the information in the U-Boot
5622image header, so the resulting S-Record file will be relative to
5623address 0x00000000. To load it to a given address, you need to
5624specify the target address as 'offset' parameter with the 'loads'
5625command.
5626
5627Example: install the image to address 0x40100000 (which on the
5628TQM8xxL is in the first Flash bank):
5629
5630	=> erase 40100000 401FFFFF
5631
5632	.......... done
5633	Erased 8 sectors
5634
5635	=> loads 40100000
5636	## Ready for S-Record download ...
5637	~>examples/image.srec
5638	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5639	...
5640	15989 15990 15991 15992
5641	[file transfer complete]
5642	[connected]
5643	## Start Addr = 0x00000000
5644
5645
5646You can check the success of the download using the 'iminfo' command;
5647this includes a checksum verification so you can be sure no data
5648corruption happened:
5649
5650	=> imi 40100000
5651
5652	## Checking Image at 40100000 ...
5653	   Image Name:	 2.2.13 for initrd on TQM850L
5654	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5655	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5656	   Load Address: 00000000
5657	   Entry Point:	 0000000c
5658	   Verifying Checksum ... OK
5659
5660
5661Boot Linux:
5662-----------
5663
5664The "bootm" command is used to boot an application that is stored in
5665memory (RAM or Flash). In case of a Linux kernel image, the contents
5666of the "bootargs" environment variable is passed to the kernel as
5667parameters. You can check and modify this variable using the
5668"printenv" and "setenv" commands:
5669
5670
5671	=> printenv bootargs
5672	bootargs=root=/dev/ram
5673
5674	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5675
5676	=> printenv bootargs
5677	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5678
5679	=> bootm 40020000
5680	## Booting Linux kernel at 40020000 ...
5681	   Image Name:	 2.2.13 for NFS on TQM850L
5682	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5683	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5684	   Load Address: 00000000
5685	   Entry Point:	 0000000c
5686	   Verifying Checksum ... OK
5687	   Uncompressing Kernel Image ... OK
5688	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
5689	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5690	time_init: decrementer frequency = 187500000/60
5691	Calibrating delay loop... 49.77 BogoMIPS
5692	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5693	...
5694
5695If you want to boot a Linux kernel with initial RAM disk, you pass
5696the memory addresses of both the kernel and the initrd image (PPBCOOT
5697format!) to the "bootm" command:
5698
5699	=> imi 40100000 40200000
5700
5701	## Checking Image at 40100000 ...
5702	   Image Name:	 2.2.13 for initrd on TQM850L
5703	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5704	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5705	   Load Address: 00000000
5706	   Entry Point:	 0000000c
5707	   Verifying Checksum ... OK
5708
5709	## Checking Image at 40200000 ...
5710	   Image Name:	 Simple Ramdisk Image
5711	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5712	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5713	   Load Address: 00000000
5714	   Entry Point:	 00000000
5715	   Verifying Checksum ... OK
5716
5717	=> bootm 40100000 40200000
5718	## Booting Linux kernel 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	   Uncompressing Kernel Image ... OK
5726	## Loading RAMDisk 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	   Loading Ramdisk ... OK
5734	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
5735	Boot arguments: root=/dev/ram
5736	time_init: decrementer frequency = 187500000/60
5737	Calibrating delay loop... 49.77 BogoMIPS
5738	...
5739	RAMDISK: Compressed image found at block 0
5740	VFS: Mounted root (ext2 filesystem).
5741
5742	bash#
5743
5744Boot Linux and pass a flat device tree:
5745-----------
5746
5747First, U-Boot must be compiled with the appropriate defines. See the section
5748titled "Linux Kernel Interface" above for a more in depth explanation. The
5749following is an example of how to start a kernel and pass an updated
5750flat device tree:
5751
5752=> print oftaddr
5753oftaddr=0x300000
5754=> print oft
5755oft=oftrees/mpc8540ads.dtb
5756=> tftp $oftaddr $oft
5757Speed: 1000, full duplex
5758Using TSEC0 device
5759TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5760Filename 'oftrees/mpc8540ads.dtb'.
5761Load address: 0x300000
5762Loading: #
5763done
5764Bytes transferred = 4106 (100a hex)
5765=> tftp $loadaddr $bootfile
5766Speed: 1000, full duplex
5767Using TSEC0 device
5768TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5769Filename 'uImage'.
5770Load address: 0x200000
5771Loading:############
5772done
5773Bytes transferred = 1029407 (fb51f hex)
5774=> print loadaddr
5775loadaddr=200000
5776=> print oftaddr
5777oftaddr=0x300000
5778=> bootm $loadaddr - $oftaddr
5779## Booting image at 00200000 ...
5780   Image Name:	 Linux-2.6.17-dirty
5781   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5782   Data Size:	 1029343 Bytes = 1005.2 kB
5783   Load Address: 00000000
5784   Entry Point:	 00000000
5785   Verifying Checksum ... OK
5786   Uncompressing Kernel Image ... OK
5787Booting using flat device tree at 0x300000
5788Using MPC85xx ADS machine description
5789Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5790[snip]
5791
5792
5793More About U-Boot Image Types:
5794------------------------------
5795
5796U-Boot supports the following image types:
5797
5798   "Standalone Programs" are directly runnable in the environment
5799	provided by U-Boot; it is expected that (if they behave
5800	well) you can continue to work in U-Boot after return from
5801	the Standalone Program.
5802   "OS Kernel Images" are usually images of some Embedded OS which
5803	will take over control completely. Usually these programs
5804	will install their own set of exception handlers, device
5805	drivers, set up the MMU, etc. - this means, that you cannot
5806	expect to re-enter U-Boot except by resetting the CPU.
5807   "RAMDisk Images" are more or less just data blocks, and their
5808	parameters (address, size) are passed to an OS kernel that is
5809	being started.
5810   "Multi-File Images" contain several images, typically an OS
5811	(Linux) kernel image and one or more data images like
5812	RAMDisks. This construct is useful for instance when you want
5813	to boot over the network using BOOTP etc., where the boot
5814	server provides just a single image file, but you want to get
5815	for instance an OS kernel and a RAMDisk image.
5816
5817	"Multi-File Images" start with a list of image sizes, each
5818	image size (in bytes) specified by an "uint32_t" in network
5819	byte order. This list is terminated by an "(uint32_t)0".
5820	Immediately after the terminating 0 follow the images, one by
5821	one, all aligned on "uint32_t" boundaries (size rounded up to
5822	a multiple of 4 bytes).
5823
5824   "Firmware Images" are binary images containing firmware (like
5825	U-Boot or FPGA images) which usually will be programmed to
5826	flash memory.
5827
5828   "Script files" are command sequences that will be executed by
5829	U-Boot's command interpreter; this feature is especially
5830	useful when you configure U-Boot to use a real shell (hush)
5831	as command interpreter.
5832
5833Booting the Linux zImage:
5834-------------------------
5835
5836On some platforms, it's possible to boot Linux zImage. This is done
5837using the "bootz" command. The syntax of "bootz" command is the same
5838as the syntax of "bootm" command.
5839
5840Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5841kernel with raw initrd images. The syntax is slightly different, the
5842address of the initrd must be augmented by it's size, in the following
5843format: "<initrd addres>:<initrd size>".
5844
5845
5846Standalone HOWTO:
5847=================
5848
5849One of the features of U-Boot is that you can dynamically load and
5850run "standalone" applications, which can use some resources of
5851U-Boot like console I/O functions or interrupt services.
5852
5853Two simple examples are included with the sources:
5854
5855"Hello World" Demo:
5856-------------------
5857
5858'examples/hello_world.c' contains a small "Hello World" Demo
5859application; it is automatically compiled when you build U-Boot.
5860It's configured to run at address 0x00040004, so you can play with it
5861like that:
5862
5863	=> loads
5864	## Ready for S-Record download ...
5865	~>examples/hello_world.srec
5866	1 2 3 4 5 6 7 8 9 10 11 ...
5867	[file transfer complete]
5868	[connected]
5869	## Start Addr = 0x00040004
5870
5871	=> go 40004 Hello World! This is a test.
5872	## Starting application at 0x00040004 ...
5873	Hello World
5874	argc = 7
5875	argv[0] = "40004"
5876	argv[1] = "Hello"
5877	argv[2] = "World!"
5878	argv[3] = "This"
5879	argv[4] = "is"
5880	argv[5] = "a"
5881	argv[6] = "test."
5882	argv[7] = "<NULL>"
5883	Hit any key to exit ...
5884
5885	## Application terminated, rc = 0x0
5886
5887Another example, which demonstrates how to register a CPM interrupt
5888handler with the U-Boot code, can be found in 'examples/timer.c'.
5889Here, a CPM timer is set up to generate an interrupt every second.
5890The interrupt service routine is trivial, just printing a '.'
5891character, but this is just a demo program. The application can be
5892controlled by the following keys:
5893
5894	? - print current values og the CPM Timer registers
5895	b - enable interrupts and start timer
5896	e - stop timer and disable interrupts
5897	q - quit application
5898
5899	=> loads
5900	## Ready for S-Record download ...
5901	~>examples/timer.srec
5902	1 2 3 4 5 6 7 8 9 10 11 ...
5903	[file transfer complete]
5904	[connected]
5905	## Start Addr = 0x00040004
5906
5907	=> go 40004
5908	## Starting application at 0x00040004 ...
5909	TIMERS=0xfff00980
5910	Using timer 1
5911	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5912
5913Hit 'b':
5914	[q, b, e, ?] Set interval 1000000 us
5915	Enabling timer
5916Hit '?':
5917	[q, b, e, ?] ........
5918	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5919Hit '?':
5920	[q, b, e, ?] .
5921	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5922Hit '?':
5923	[q, b, e, ?] .
5924	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5925Hit '?':
5926	[q, b, e, ?] .
5927	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5928Hit 'e':
5929	[q, b, e, ?] ...Stopping timer
5930Hit 'q':
5931	[q, b, e, ?] ## Application terminated, rc = 0x0
5932
5933
5934Minicom warning:
5935================
5936
5937Over time, many people have reported problems when trying to use the
5938"minicom" terminal emulation program for serial download. I (wd)
5939consider minicom to be broken, and recommend not to use it. Under
5940Unix, I recommend to use C-Kermit for general purpose use (and
5941especially for kermit binary protocol download ("loadb" command), and
5942use "cu" for S-Record download ("loads" command).  See
5943http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5944for help with kermit.
5945
5946
5947Nevertheless, if you absolutely want to use it try adding this
5948configuration to your "File transfer protocols" section:
5949
5950	   Name	   Program			Name U/D FullScr IO-Red. Multi
5951	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5952	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5953
5954
5955NetBSD Notes:
5956=============
5957
5958Starting at version 0.9.2, U-Boot supports NetBSD both as host
5959(build U-Boot) and target system (boots NetBSD/mpc8xx).
5960
5961Building requires a cross environment; it is known to work on
5962NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5963need gmake since the Makefiles are not compatible with BSD make).
5964Note that the cross-powerpc package does not install include files;
5965attempting to build U-Boot will fail because <machine/ansi.h> is
5966missing.  This file has to be installed and patched manually:
5967
5968	# cd /usr/pkg/cross/powerpc-netbsd/include
5969	# mkdir powerpc
5970	# ln -s powerpc machine
5971	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5972	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5973
5974Native builds *don't* work due to incompatibilities between native
5975and U-Boot include files.
5976
5977Booting assumes that (the first part of) the image booted is a
5978stage-2 loader which in turn loads and then invokes the kernel
5979proper. Loader sources will eventually appear in the NetBSD source
5980tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5981meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5982
5983
5984Implementation Internals:
5985=========================
5986
5987The following is not intended to be a complete description of every
5988implementation detail. However, it should help to understand the
5989inner workings of U-Boot and make it easier to port it to custom
5990hardware.
5991
5992
5993Initial Stack, Global Data:
5994---------------------------
5995
5996The implementation of U-Boot is complicated by the fact that U-Boot
5997starts running out of ROM (flash memory), usually without access to
5998system RAM (because the memory controller is not initialized yet).
5999This means that we don't have writable Data or BSS segments, and BSS
6000is not initialized as zero. To be able to get a C environment working
6001at all, we have to allocate at least a minimal stack. Implementation
6002options for this are defined and restricted by the CPU used: Some CPU
6003models provide on-chip memory (like the IMMR area on MPC8xx and
6004MPC826x processors), on others (parts of) the data cache can be
6005locked as (mis-) used as memory, etc.
6006
6007	Chris Hallinan posted a good summary of these issues to the
6008	U-Boot mailing list:
6009
6010	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
6011	From: "Chris Hallinan" <clh@net1plus.com>
6012	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
6013	...
6014
6015	Correct me if I'm wrong, folks, but the way I understand it
6016	is this: Using DCACHE as initial RAM for Stack, etc, does not
6017	require any physical RAM backing up the cache. The cleverness
6018	is that the cache is being used as a temporary supply of
6019	necessary storage before the SDRAM controller is setup. It's
6020	beyond the scope of this list to explain the details, but you
6021	can see how this works by studying the cache architecture and
6022	operation in the architecture and processor-specific manuals.
6023
6024	OCM is On Chip Memory, which I believe the 405GP has 4K. It
6025	is another option for the system designer to use as an
6026	initial stack/RAM area prior to SDRAM being available. Either
6027	option should work for you. Using CS 4 should be fine if your
6028	board designers haven't used it for something that would
6029	cause you grief during the initial boot! It is frequently not
6030	used.
6031
6032	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
6033	with your processor/board/system design. The default value
6034	you will find in any recent u-boot distribution in
6035	walnut.h should work for you. I'd set it to a value larger
6036	than your SDRAM module. If you have a 64MB SDRAM module, set
6037	it above 400_0000. Just make sure your board has no resources
6038	that are supposed to respond to that address! That code in
6039	start.S has been around a while and should work as is when
6040	you get the config right.
6041
6042	-Chris Hallinan
6043	DS4.COM, Inc.
6044
6045It is essential to remember this, since it has some impact on the C
6046code for the initialization procedures:
6047
6048* Initialized global data (data segment) is read-only. Do not attempt
6049  to write it.
6050
6051* Do not use any uninitialized global data (or implicitly initialized
6052  as zero data - BSS segment) at all - this is undefined, initiali-
6053  zation is performed later (when relocating to RAM).
6054
6055* Stack space is very limited. Avoid big data buffers or things like
6056  that.
6057
6058Having only the stack as writable memory limits means we cannot use
6059normal global data to share information between the code. But it
6060turned out that the implementation of U-Boot can be greatly
6061simplified by making a global data structure (gd_t) available to all
6062functions. We could pass a pointer to this data as argument to _all_
6063functions, but this would bloat the code. Instead we use a feature of
6064the GCC compiler (Global Register Variables) to share the data: we
6065place a pointer (gd) to the global data into a register which we
6066reserve for this purpose.
6067
6068When choosing a register for such a purpose we are restricted by the
6069relevant  (E)ABI  specifications for the current architecture, and by
6070GCC's implementation.
6071
6072For PowerPC, the following registers have specific use:
6073	R1:	stack pointer
6074	R2:	reserved for system use
6075	R3-R4:	parameter passing and return values
6076	R5-R10: parameter passing
6077	R13:	small data area pointer
6078	R30:	GOT pointer
6079	R31:	frame pointer
6080
6081	(U-Boot also uses R12 as internal GOT pointer. r12
6082	is a volatile register so r12 needs to be reset when
6083	going back and forth between asm and C)
6084
6085    ==> U-Boot will use R2 to hold a pointer to the global data
6086
6087    Note: on PPC, we could use a static initializer (since the
6088    address of the global data structure is known at compile time),
6089    but it turned out that reserving a register results in somewhat
6090    smaller code - although the code savings are not that big (on
6091    average for all boards 752 bytes for the whole U-Boot image,
6092    624 text + 127 data).
6093
6094On Blackfin, the normal C ABI (except for P3) is followed as documented here:
6095	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
6096
6097    ==> U-Boot will use P3 to hold a pointer to the global data
6098
6099On ARM, the following registers are used:
6100
6101	R0:	function argument word/integer result
6102	R1-R3:	function argument word
6103	R9:	platform specific
6104	R10:	stack limit (used only if stack checking is enabled)
6105	R11:	argument (frame) pointer
6106	R12:	temporary workspace
6107	R13:	stack pointer
6108	R14:	link register
6109	R15:	program counter
6110
6111    ==> U-Boot will use R9 to hold a pointer to the global data
6112
6113    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
6114
6115On Nios II, the ABI is documented here:
6116	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
6117
6118    ==> U-Boot will use gp to hold a pointer to the global data
6119
6120    Note: on Nios II, we give "-G0" option to gcc and don't use gp
6121    to access small data sections, so gp is free.
6122
6123On NDS32, the following registers are used:
6124
6125	R0-R1:	argument/return
6126	R2-R5:	argument
6127	R15:	temporary register for assembler
6128	R16:	trampoline register
6129	R28:	frame pointer (FP)
6130	R29:	global pointer (GP)
6131	R30:	link register (LP)
6132	R31:	stack pointer (SP)
6133	PC:	program counter (PC)
6134
6135    ==> U-Boot will use R10 to hold a pointer to the global data
6136
6137NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
6138or current versions of GCC may "optimize" the code too much.
6139
6140Memory Management:
6141------------------
6142
6143U-Boot runs in system state and uses physical addresses, i.e. the
6144MMU is not used either for address mapping nor for memory protection.
6145
6146The available memory is mapped to fixed addresses using the memory
6147controller. In this process, a contiguous block is formed for each
6148memory type (Flash, SDRAM, SRAM), even when it consists of several
6149physical memory banks.
6150
6151U-Boot is installed in the first 128 kB of the first Flash bank (on
6152TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
6153booting and sizing and initializing DRAM, the code relocates itself
6154to the upper end of DRAM. Immediately below the U-Boot code some
6155memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
6156configuration setting]. Below that, a structure with global Board
6157Info data is placed, followed by the stack (growing downward).
6158
6159Additionally, some exception handler code is copied to the low 8 kB
6160of DRAM (0x00000000 ... 0x00001FFF).
6161
6162So a typical memory configuration with 16 MB of DRAM could look like
6163this:
6164
6165	0x0000 0000	Exception Vector code
6166	      :
6167	0x0000 1FFF
6168	0x0000 2000	Free for Application Use
6169	      :
6170	      :
6171
6172	      :
6173	      :
6174	0x00FB FF20	Monitor Stack (Growing downward)
6175	0x00FB FFAC	Board Info Data and permanent copy of global data
6176	0x00FC 0000	Malloc Arena
6177	      :
6178	0x00FD FFFF
6179	0x00FE 0000	RAM Copy of Monitor Code
6180	...		eventually: LCD or video framebuffer
6181	...		eventually: pRAM (Protected RAM - unchanged by reset)
6182	0x00FF FFFF	[End of RAM]
6183
6184
6185System Initialization:
6186----------------------
6187
6188In the reset configuration, U-Boot starts at the reset entry point
6189(on most PowerPC systems at address 0x00000100). Because of the reset
6190configuration for CS0# this is a mirror of the on board Flash memory.
6191To be able to re-map memory U-Boot then jumps to its link address.
6192To be able to implement the initialization code in C, a (small!)
6193initial stack is set up in the internal Dual Ported RAM (in case CPUs
6194which provide such a feature like MPC8xx or MPC8260), or in a locked
6195part of the data cache. After that, U-Boot initializes the CPU core,
6196the caches and the SIU.
6197
6198Next, all (potentially) available memory banks are mapped using a
6199preliminary mapping. For example, we put them on 512 MB boundaries
6200(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
6201on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
6202programmed for SDRAM access. Using the temporary configuration, a
6203simple memory test is run that determines the size of the SDRAM
6204banks.
6205
6206When there is more than one SDRAM bank, and the banks are of
6207different size, the largest is mapped first. For equal size, the first
6208bank (CS2#) is mapped first. The first mapping is always for address
62090x00000000, with any additional banks following immediately to create
6210contiguous memory starting from 0.
6211
6212Then, the monitor installs itself at the upper end of the SDRAM area
6213and allocates memory for use by malloc() and for the global Board
6214Info data; also, the exception vector code is copied to the low RAM
6215pages, and the final stack is set up.
6216
6217Only after this relocation will you have a "normal" C environment;
6218until that you are restricted in several ways, mostly because you are
6219running from ROM, and because the code will have to be relocated to a
6220new address in RAM.
6221
6222
6223U-Boot Porting Guide:
6224----------------------
6225
6226[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
6227list, October 2002]
6228
6229
6230int main(int argc, char *argv[])
6231{
6232	sighandler_t no_more_time;
6233
6234	signal(SIGALRM, no_more_time);
6235	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
6236
6237	if (available_money > available_manpower) {
6238		Pay consultant to port U-Boot;
6239		return 0;
6240	}
6241
6242	Download latest U-Boot source;
6243
6244	Subscribe to u-boot mailing list;
6245
6246	if (clueless)
6247		email("Hi, I am new to U-Boot, how do I get started?");
6248
6249	while (learning) {
6250		Read the README file in the top level directory;
6251		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
6252		Read applicable doc/*.README;
6253		Read the source, Luke;
6254		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
6255	}
6256
6257	if (available_money > toLocalCurrency ($2500))
6258		Buy a BDI3000;
6259	else
6260		Add a lot of aggravation and time;
6261
6262	if (a similar board exists) {	/* hopefully... */
6263		cp -a board/<similar> board/<myboard>
6264		cp include/configs/<similar>.h include/configs/<myboard>.h
6265	} else {
6266		Create your own board support subdirectory;
6267		Create your own board include/configs/<myboard>.h file;
6268	}
6269	Edit new board/<myboard> files
6270	Edit new include/configs/<myboard>.h
6271
6272	while (!accepted) {
6273		while (!running) {
6274			do {
6275				Add / modify source code;
6276			} until (compiles);
6277			Debug;
6278			if (clueless)
6279				email("Hi, I am having problems...");
6280		}
6281		Send patch file to the U-Boot email list;
6282		if (reasonable critiques)
6283			Incorporate improvements from email list code review;
6284		else
6285			Defend code as written;
6286	}
6287
6288	return 0;
6289}
6290
6291void no_more_time (int sig)
6292{
6293      hire_a_guru();
6294}
6295
6296
6297Coding Standards:
6298-----------------
6299
6300All contributions to U-Boot should conform to the Linux kernel
6301coding style; see the file "Documentation/CodingStyle" and the script
6302"scripts/Lindent" in your Linux kernel source directory.
6303
6304Source files originating from a different project (for example the
6305MTD subsystem) are generally exempt from these guidelines and are not
6306reformatted to ease subsequent migration to newer versions of those
6307sources.
6308
6309Please note that U-Boot is implemented in C (and to some small parts in
6310Assembler); no C++ is used, so please do not use C++ style comments (//)
6311in your code.
6312
6313Please also stick to the following formatting rules:
6314- remove any trailing white space
6315- use TAB characters for indentation and vertical alignment, not spaces
6316- make sure NOT to use DOS '\r\n' line feeds
6317- do not add more than 2 consecutive empty lines to source files
6318- do not add trailing empty lines to source files
6319
6320Submissions which do not conform to the standards may be returned
6321with a request to reformat the changes.
6322
6323
6324Submitting Patches:
6325-------------------
6326
6327Since the number of patches for U-Boot is growing, we need to
6328establish some rules. Submissions which do not conform to these rules
6329may be rejected, even when they contain important and valuable stuff.
6330
6331Please see http://www.denx.de/wiki/U-Boot/Patches for details.
6332
6333Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
6334see http://lists.denx.de/mailman/listinfo/u-boot
6335
6336When you send a patch, please include the following information with
6337it:
6338
6339* For bug fixes: a description of the bug and how your patch fixes
6340  this bug. Please try to include a way of demonstrating that the
6341  patch actually fixes something.
6342
6343* For new features: a description of the feature and your
6344  implementation.
6345
6346* A CHANGELOG entry as plaintext (separate from the patch)
6347
6348* For major contributions, add a MAINTAINERS file with your
6349  information and associated file and directory references.
6350
6351* When you add support for a new board, don't forget to add a
6352  maintainer e-mail address to the boards.cfg file, too.
6353
6354* If your patch adds new configuration options, don't forget to
6355  document these in the README file.
6356
6357* The patch itself. If you are using git (which is *strongly*
6358  recommended) you can easily generate the patch using the
6359  "git format-patch". If you then use "git send-email" to send it to
6360  the U-Boot mailing list, you will avoid most of the common problems
6361  with some other mail clients.
6362
6363  If you cannot use git, use "diff -purN OLD NEW". If your version of
6364  diff does not support these options, then get the latest version of
6365  GNU diff.
6366
6367  The current directory when running this command shall be the parent
6368  directory of the U-Boot source tree (i. e. please make sure that
6369  your patch includes sufficient directory information for the
6370  affected files).
6371
6372  We prefer patches as plain text. MIME attachments are discouraged,
6373  and compressed attachments must not be used.
6374
6375* If one logical set of modifications affects or creates several
6376  files, all these changes shall be submitted in a SINGLE patch file.
6377
6378* Changesets that contain different, unrelated modifications shall be
6379  submitted as SEPARATE patches, one patch per changeset.
6380
6381
6382Notes:
6383
6384* Before sending the patch, run the buildman script on your patched
6385  source tree and make sure that no errors or warnings are reported
6386  for any of the boards.
6387
6388* Keep your modifications to the necessary minimum: A patch
6389  containing several unrelated changes or arbitrary reformats will be
6390  returned with a request to re-formatting / split it.
6391
6392* If you modify existing code, make sure that your new code does not
6393  add to the memory footprint of the code ;-) Small is beautiful!
6394  When adding new features, these should compile conditionally only
6395  (using #ifdef), and the resulting code with the new feature
6396  disabled must not need more memory than the old code without your
6397  modification.
6398
6399* Remember that there is a size limit of 100 kB per message on the
6400  u-boot mailing list. Bigger patches will be moderated. If they are
6401  reasonable and not too big, they will be acknowledged. But patches
6402  bigger than the size limit should be avoided.
6403