xref: /rk3399_rockchip-uboot/README (revision 0f0f75774e8bbe058fccd5b7c4fce6988c80c4e5)
1#
2# (C) Copyright 2000 - 2013
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# SPDX-License-Identifier:	GPL-2.0+
6#
7
8Summary:
9========
10
11This directory contains the source code for U-Boot, a boot loader for
12Embedded boards based on PowerPC, ARM, MIPS and several other
13processors, which can be installed in a boot ROM and used to
14initialize and test the hardware or to download and run application
15code.
16
17The development of U-Boot is closely related to Linux: some parts of
18the source code originate in the Linux source tree, we have some
19header files in common, and special provision has been made to
20support booting of Linux images.
21
22Some attention has been paid to make this software easily
23configurable and extendable. For instance, all monitor commands are
24implemented with the same call interface, so that it's very easy to
25add new commands. Also, instead of permanently adding rarely used
26code (for instance hardware test utilities) to the monitor, you can
27load and run it dynamically.
28
29
30Status:
31=======
32
33In general, all boards for which a configuration option exists in the
34Makefile have been tested to some extent and can be considered
35"working". In fact, many of them are used in production systems.
36
37In case of problems see the CHANGELOG and CREDITS files to find out
38who contributed the specific port. The boards.cfg file lists board
39maintainers.
40
41Note: There is no CHANGELOG file in the actual U-Boot source tree;
42it can be created dynamically from the Git log using:
43
44	make CHANGELOG
45
46
47Where to get help:
48==================
49
50In case you have questions about, problems with or contributions for
51U-Boot you should send a message to the U-Boot mailing list at
52<u-boot@lists.denx.de>. There is also an archive of previous traffic
53on the mailing list - please search the archive before asking FAQ's.
54Please see http://lists.denx.de/pipermail/u-boot and
55http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
56
57
58Where to get source code:
59=========================
60
61The U-Boot source code is maintained in the git repository at
62git://www.denx.de/git/u-boot.git ; you can browse it online at
63http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
64
65The "snapshot" links on this page allow you to download tarballs of
66any version you might be interested in. Official releases are also
67available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
68directory.
69
70Pre-built (and tested) images are available from
71ftp://ftp.denx.de/pub/u-boot/images/
72
73
74Where we come from:
75===================
76
77- start from 8xxrom sources
78- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
79- clean up code
80- make it easier to add custom boards
81- make it possible to add other [PowerPC] CPUs
82- extend functions, especially:
83  * Provide extended interface to Linux boot loader
84  * S-Record download
85  * network boot
86  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
87- create ARMBoot project (http://sourceforge.net/projects/armboot)
88- add other CPU families (starting with ARM)
89- create U-Boot project (http://sourceforge.net/projects/u-boot)
90- current project page: see http://www.denx.de/wiki/U-Boot
91
92
93Names and Spelling:
94===================
95
96The "official" name of this project is "Das U-Boot". The spelling
97"U-Boot" shall be used in all written text (documentation, comments
98in source files etc.). Example:
99
100	This is the README file for the U-Boot project.
101
102File names etc. shall be based on the string "u-boot". Examples:
103
104	include/asm-ppc/u-boot.h
105
106	#include <asm/u-boot.h>
107
108Variable names, preprocessor constants etc. shall be either based on
109the string "u_boot" or on "U_BOOT". Example:
110
111	U_BOOT_VERSION		u_boot_logo
112	IH_OS_U_BOOT		u_boot_hush_start
113
114
115Versioning:
116===========
117
118Starting with the release in October 2008, the names of the releases
119were changed from numerical release numbers without deeper meaning
120into a time stamp based numbering. Regular releases are identified by
121names consisting of the calendar year and month of the release date.
122Additional fields (if present) indicate release candidates or bug fix
123releases in "stable" maintenance trees.
124
125Examples:
126	U-Boot v2009.11	    - Release November 2009
127	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
128	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
129
130
131Directory Hierarchy:
132====================
133
134/arch			Architecture specific files
135  /arm			Files generic to ARM architecture
136    /cpu		CPU specific files
137      /arm720t		Files specific to ARM 720 CPUs
138      /arm920t		Files specific to ARM 920 CPUs
139	/at91		Files specific to Atmel AT91RM9200 CPU
140	/imx		Files specific to Freescale MC9328 i.MX CPUs
141	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
142      /arm926ejs	Files specific to ARM 926 CPUs
143      /arm1136		Files specific to ARM 1136 CPUs
144      /ixp		Files specific to Intel XScale IXP CPUs
145      /pxa		Files specific to Intel XScale PXA CPUs
146      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
147    /lib		Architecture specific library files
148  /avr32		Files generic to AVR32 architecture
149    /cpu		CPU specific files
150    /lib		Architecture specific library files
151  /blackfin		Files generic to Analog Devices Blackfin architecture
152    /cpu		CPU specific files
153    /lib		Architecture specific library files
154  /m68k			Files generic to m68k architecture
155    /cpu		CPU specific files
156      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
157      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
158      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
159      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
160      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
161    /lib		Architecture specific library files
162  /microblaze		Files generic to microblaze architecture
163    /cpu		CPU specific files
164    /lib		Architecture specific library files
165  /mips			Files generic to MIPS architecture
166    /cpu		CPU specific files
167      /mips32		Files specific to MIPS32 CPUs
168      /xburst		Files specific to Ingenic XBurst CPUs
169    /lib		Architecture specific library files
170  /nds32		Files generic to NDS32 architecture
171    /cpu		CPU specific files
172      /n1213		Files specific to Andes Technology N1213 CPUs
173    /lib		Architecture specific library files
174  /nios2		Files generic to Altera NIOS2 architecture
175    /cpu		CPU specific files
176    /lib		Architecture specific library files
177  /openrisc		Files generic to OpenRISC architecture
178    /cpu		CPU specific files
179    /lib		Architecture specific library files
180  /powerpc		Files generic to PowerPC architecture
181    /cpu		CPU specific files
182      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
183      /mpc5xx		Files specific to Freescale MPC5xx CPUs
184      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
185      /mpc8xx		Files specific to Freescale MPC8xx CPUs
186      /mpc824x		Files specific to Freescale MPC824x CPUs
187      /mpc8260		Files specific to Freescale MPC8260 CPUs
188      /mpc85xx		Files specific to Freescale MPC85xx CPUs
189      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
190    /lib		Architecture specific library files
191  /sh			Files generic to SH architecture
192    /cpu		CPU specific files
193      /sh2		Files specific to sh2 CPUs
194      /sh3		Files specific to sh3 CPUs
195      /sh4		Files specific to sh4 CPUs
196    /lib		Architecture specific library files
197  /sparc		Files generic to SPARC architecture
198    /cpu		CPU specific files
199      /leon2		Files specific to Gaisler LEON2 SPARC CPU
200      /leon3		Files specific to Gaisler LEON3 SPARC CPU
201    /lib		Architecture specific library files
202  /x86			Files generic to x86 architecture
203    /cpu		CPU specific files
204    /lib		Architecture specific library files
205/api			Machine/arch independent API for external apps
206/board			Board dependent files
207/common			Misc architecture independent functions
208/disk			Code for disk drive partition handling
209/doc			Documentation (don't expect too much)
210/drivers		Commonly used device drivers
211/dts			Contains Makefile for building internal U-Boot fdt.
212/examples		Example code for standalone applications, etc.
213/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
214/include		Header Files
215/lib			Files generic to all architectures
216  /libfdt		Library files to support flattened device trees
217  /lzma			Library files to support LZMA decompression
218  /lzo			Library files to support LZO decompression
219/net			Networking code
220/post			Power On Self Test
221/spl			Secondary Program Loader framework
222/tools			Tools to build S-Record or U-Boot images, etc.
223
224Software Configuration:
225=======================
226
227Configuration is usually done using C preprocessor defines; the
228rationale behind that is to avoid dead code whenever possible.
229
230There are two classes of configuration variables:
231
232* Configuration _OPTIONS_:
233  These are selectable by the user and have names beginning with
234  "CONFIG_".
235
236* Configuration _SETTINGS_:
237  These depend on the hardware etc. and should not be meddled with if
238  you don't know what you're doing; they have names beginning with
239  "CONFIG_SYS_".
240
241Later we will add a configuration tool - probably similar to or even
242identical to what's used for the Linux kernel. Right now, we have to
243do the configuration by hand, which means creating some symbolic
244links and editing some configuration files. We use the TQM8xxL boards
245as an example here.
246
247
248Selection of Processor Architecture and Board Type:
249---------------------------------------------------
250
251For all supported boards there are ready-to-use default
252configurations available; just type "make <board_name>_config".
253
254Example: For a TQM823L module type:
255
256	cd u-boot
257	make TQM823L_config
258
259For the Cogent platform, you need to specify the CPU type as well;
260e.g. "make cogent_mpc8xx_config". And also configure the cogent
261directory according to the instructions in cogent/README.
262
263
264Configuration Options:
265----------------------
266
267Configuration depends on the combination of board and CPU type; all
268such information is kept in a configuration file
269"include/configs/<board_name>.h".
270
271Example: For a TQM823L module, all configuration settings are in
272"include/configs/TQM823L.h".
273
274
275Many of the options are named exactly as the corresponding Linux
276kernel configuration options. The intention is to make it easier to
277build a config tool - later.
278
279
280The following options need to be configured:
281
282- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
283
284- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
285
286- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
287		Define exactly one, e.g. CONFIG_ATSTK1002
288
289- CPU Module Type: (if CONFIG_COGENT is defined)
290		Define exactly one of
291		CONFIG_CMA286_60_OLD
292--- FIXME --- not tested yet:
293		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
294		CONFIG_CMA287_23, CONFIG_CMA287_50
295
296- Motherboard Type: (if CONFIG_COGENT is defined)
297		Define exactly one of
298		CONFIG_CMA101, CONFIG_CMA102
299
300- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
301		Define one or more of
302		CONFIG_CMA302
303
304- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
305		Define one or more of
306		CONFIG_LCD_HEARTBEAT	- update a character position on
307					  the LCD display every second with
308					  a "rotator" |\-/|\-/
309
310- Board flavour: (if CONFIG_MPC8260ADS is defined)
311		CONFIG_ADSTYPE
312		Possible values are:
313			CONFIG_SYS_8260ADS	- original MPC8260ADS
314			CONFIG_SYS_8266ADS	- MPC8266ADS
315			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
316			CONFIG_SYS_8272ADS	- MPC8272ADS
317
318- Marvell Family Member
319		CONFIG_SYS_MVFS		- define it if you want to enable
320					  multiple fs option at one time
321					  for marvell soc family
322
323- MPC824X Family Member (if CONFIG_MPC824X is defined)
324		Define exactly one of
325		CONFIG_MPC8240, CONFIG_MPC8245
326
327- 8xx CPU Options: (if using an MPC8xx CPU)
328		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
329					  get_gclk_freq() cannot work
330					  e.g. if there is no 32KHz
331					  reference PIT/RTC clock
332		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
333					  or XTAL/EXTAL)
334
335- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
336		CONFIG_SYS_8xx_CPUCLK_MIN
337		CONFIG_SYS_8xx_CPUCLK_MAX
338		CONFIG_8xx_CPUCLK_DEFAULT
339			See doc/README.MPC866
340
341		CONFIG_SYS_MEASURE_CPUCLK
342
343		Define this to measure the actual CPU clock instead
344		of relying on the correctness of the configured
345		values. Mostly useful for board bringup to make sure
346		the PLL is locked at the intended frequency. Note
347		that this requires a (stable) reference clock (32 kHz
348		RTC clock or CONFIG_SYS_8XX_XIN)
349
350		CONFIG_SYS_DELAYED_ICACHE
351
352		Define this option if you want to enable the
353		ICache only when Code runs from RAM.
354
355- 85xx CPU Options:
356		CONFIG_SYS_PPC64
357
358		Specifies that the core is a 64-bit PowerPC implementation (implements
359		the "64" category of the Power ISA). This is necessary for ePAPR
360		compliance, among other possible reasons.
361
362		CONFIG_SYS_FSL_TBCLK_DIV
363
364		Defines the core time base clock divider ratio compared to the
365		system clock.  On most PQ3 devices this is 8, on newer QorIQ
366		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
367
368		CONFIG_SYS_FSL_PCIE_COMPAT
369
370		Defines the string to utilize when trying to match PCIe device
371		tree nodes for the given platform.
372
373		CONFIG_SYS_PPC_E500_DEBUG_TLB
374
375		Enables a temporary TLB entry to be used during boot to work
376		around limitations in e500v1 and e500v2 external debugger
377		support. This reduces the portions of the boot code where
378		breakpoints and single stepping do not work.  The value of this
379		symbol should be set to the TLB1 entry to be used for this
380		purpose.
381
382		CONFIG_SYS_FSL_ERRATUM_A004510
383
384		Enables a workaround for erratum A004510.  If set,
385		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
386		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
387
388		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
389		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
390
391		Defines one or two SoC revisions (low 8 bits of SVR)
392		for which the A004510 workaround should be applied.
393
394		The rest of SVR is either not relevant to the decision
395		of whether the erratum is present (e.g. p2040 versus
396		p2041) or is implied by the build target, which controls
397		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
398
399		See Freescale App Note 4493 for more information about
400		this erratum.
401
402		CONFIG_A003399_NOR_WORKAROUND
403		Enables a workaround for IFC erratum A003399. It is only
404		requred during NOR boot.
405
406		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
407
408		This is the value to write into CCSR offset 0x18600
409		according to the A004510 workaround.
410
411		CONFIG_SYS_FSL_DSP_DDR_ADDR
412		This value denotes start offset of DDR memory which is
413		connected exclusively to the DSP cores.
414
415		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
416		This value denotes start offset of M2 memory
417		which is directly connected to the DSP core.
418
419		CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
420		This value denotes start offset of M3 memory which is directly
421		connected to the DSP core.
422
423		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
424		This value denotes start offset of DSP CCSR space.
425
426		CONFIG_SYS_FSL_DDR_EMU
427		Specify emulator support for DDR. Some DDR features such as
428		deskew training are not available.
429
430- Generic CPU options:
431		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
432
433		Defines the endianess of the CPU. Implementation of those
434		values is arch specific.
435
436- Intel Monahans options:
437		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
438
439		Defines the Monahans run mode to oscillator
440		ratio. Valid values are 8, 16, 24, 31. The core
441		frequency is this value multiplied by 13 MHz.
442
443		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
444
445		Defines the Monahans turbo mode to oscillator
446		ratio. Valid values are 1 (default if undefined) and
447		2. The core frequency as calculated above is multiplied
448		by this value.
449
450- MIPS CPU options:
451		CONFIG_SYS_INIT_SP_OFFSET
452
453		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
454		pointer. This is needed for the temporary stack before
455		relocation.
456
457		CONFIG_SYS_MIPS_CACHE_MODE
458
459		Cache operation mode for the MIPS CPU.
460		See also arch/mips/include/asm/mipsregs.h.
461		Possible values are:
462			CONF_CM_CACHABLE_NO_WA
463			CONF_CM_CACHABLE_WA
464			CONF_CM_UNCACHED
465			CONF_CM_CACHABLE_NONCOHERENT
466			CONF_CM_CACHABLE_CE
467			CONF_CM_CACHABLE_COW
468			CONF_CM_CACHABLE_CUW
469			CONF_CM_CACHABLE_ACCELERATED
470
471		CONFIG_SYS_XWAY_EBU_BOOTCFG
472
473		Special option for Lantiq XWAY SoCs for booting from NOR flash.
474		See also arch/mips/cpu/mips32/start.S.
475
476		CONFIG_XWAY_SWAP_BYTES
477
478		Enable compilation of tools/xway-swap-bytes needed for Lantiq
479		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
480		be swapped if a flash programmer is used.
481
482- ARM options:
483		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
484
485		Select high exception vectors of the ARM core, e.g., do not
486		clear the V bit of the c1 register of CP15.
487
488		CONFIG_SYS_THUMB_BUILD
489
490		Use this flag to build U-Boot using the Thumb instruction
491		set for ARM architectures. Thumb instruction set provides
492		better code density. For ARM architectures that support
493		Thumb2 this flag will result in Thumb2 code generated by
494		GCC.
495
496		CONFIG_ARM_ERRATA_716044
497		CONFIG_ARM_ERRATA_742230
498		CONFIG_ARM_ERRATA_743622
499		CONFIG_ARM_ERRATA_751472
500
501		If set, the workarounds for these ARM errata are applied early
502		during U-Boot startup. Note that these options force the
503		workarounds to be applied; no CPU-type/version detection
504		exists, unlike the similar options in the Linux kernel. Do not
505		set these options unless they apply!
506
507- CPU timer options:
508		CONFIG_SYS_HZ
509
510		The frequency of the timer returned by get_timer().
511		get_timer() must operate in milliseconds and this CONFIG
512		option must be set to 1000.
513
514- Linux Kernel Interface:
515		CONFIG_CLOCKS_IN_MHZ
516
517		U-Boot stores all clock information in Hz
518		internally. For binary compatibility with older Linux
519		kernels (which expect the clocks passed in the
520		bd_info data to be in MHz) the environment variable
521		"clocks_in_mhz" can be defined so that U-Boot
522		converts clock data to MHZ before passing it to the
523		Linux kernel.
524		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
525		"clocks_in_mhz=1" is automatically included in the
526		default environment.
527
528		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
529
530		When transferring memsize parameter to linux, some versions
531		expect it to be in bytes, others in MB.
532		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
533
534		CONFIG_OF_LIBFDT
535
536		New kernel versions are expecting firmware settings to be
537		passed using flattened device trees (based on open firmware
538		concepts).
539
540		CONFIG_OF_LIBFDT
541		 * New libfdt-based support
542		 * Adds the "fdt" command
543		 * The bootm command automatically updates the fdt
544
545		OF_CPU - The proper name of the cpus node (only required for
546			MPC512X and MPC5xxx based boards).
547		OF_SOC - The proper name of the soc node (only required for
548			MPC512X and MPC5xxx based boards).
549		OF_TBCLK - The timebase frequency.
550		OF_STDOUT_PATH - The path to the console device
551
552		boards with QUICC Engines require OF_QE to set UCC MAC
553		addresses
554
555		CONFIG_OF_BOARD_SETUP
556
557		Board code has addition modification that it wants to make
558		to the flat device tree before handing it off to the kernel
559
560		CONFIG_OF_BOOT_CPU
561
562		This define fills in the correct boot CPU in the boot
563		param header, the default value is zero if undefined.
564
565		CONFIG_OF_IDE_FIXUP
566
567		U-Boot can detect if an IDE device is present or not.
568		If not, and this new config option is activated, U-Boot
569		removes the ATA node from the DTS before booting Linux,
570		so the Linux IDE driver does not probe the device and
571		crash. This is needed for buggy hardware (uc101) where
572		no pull down resistor is connected to the signal IDE5V_DD7.
573
574		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
575
576		This setting is mandatory for all boards that have only one
577		machine type and must be used to specify the machine type
578		number as it appears in the ARM machine registry
579		(see http://www.arm.linux.org.uk/developer/machines/).
580		Only boards that have multiple machine types supported
581		in a single configuration file and the machine type is
582		runtime discoverable, do not have to use this setting.
583
584- vxWorks boot parameters:
585
586		bootvx constructs a valid bootline using the following
587		environments variables: bootfile, ipaddr, serverip, hostname.
588		It loads the vxWorks image pointed bootfile.
589
590		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
591		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
592		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
593		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
594
595		CONFIG_SYS_VXWORKS_ADD_PARAMS
596
597		Add it at the end of the bootline. E.g "u=username pw=secret"
598
599		Note: If a "bootargs" environment is defined, it will overwride
600		the defaults discussed just above.
601
602- Cache Configuration:
603		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
604		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
605		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
606
607- Cache Configuration for ARM:
608		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
609				      controller
610		CONFIG_SYS_PL310_BASE - Physical base address of PL310
611					controller register space
612
613- Serial Ports:
614		CONFIG_PL010_SERIAL
615
616		Define this if you want support for Amba PrimeCell PL010 UARTs.
617
618		CONFIG_PL011_SERIAL
619
620		Define this if you want support for Amba PrimeCell PL011 UARTs.
621
622		CONFIG_PL011_CLOCK
623
624		If you have Amba PrimeCell PL011 UARTs, set this variable to
625		the clock speed of the UARTs.
626
627		CONFIG_PL01x_PORTS
628
629		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
630		define this to a list of base addresses for each (supported)
631		port. See e.g. include/configs/versatile.h
632
633		CONFIG_PL011_SERIAL_RLCR
634
635		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
636		have separate receive and transmit line control registers.  Set
637		this variable to initialize the extra register.
638
639		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
640
641		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
642		boot loader that has already initialized the UART.  Define this
643		variable to flush the UART at init time.
644
645
646- Console Interface:
647		Depending on board, define exactly one serial port
648		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
649		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
650		console by defining CONFIG_8xx_CONS_NONE
651
652		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
653		port routines must be defined elsewhere
654		(i.e. serial_init(), serial_getc(), ...)
655
656		CONFIG_CFB_CONSOLE
657		Enables console device for a color framebuffer. Needs following
658		defines (cf. smiLynxEM, i8042)
659			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
660						(default big endian)
661			VIDEO_HW_RECTFILL	graphic chip supports
662						rectangle fill
663						(cf. smiLynxEM)
664			VIDEO_HW_BITBLT		graphic chip supports
665						bit-blit (cf. smiLynxEM)
666			VIDEO_VISIBLE_COLS	visible pixel columns
667						(cols=pitch)
668			VIDEO_VISIBLE_ROWS	visible pixel rows
669			VIDEO_PIXEL_SIZE	bytes per pixel
670			VIDEO_DATA_FORMAT	graphic data format
671						(0-5, cf. cfb_console.c)
672			VIDEO_FB_ADRS		framebuffer address
673			VIDEO_KBD_INIT_FCT	keyboard int fct
674						(i.e. i8042_kbd_init())
675			VIDEO_TSTC_FCT		test char fct
676						(i.e. i8042_tstc)
677			VIDEO_GETC_FCT		get char fct
678						(i.e. i8042_getc)
679			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
680						(requires blink timer
681						cf. i8042.c)
682			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
683			CONFIG_CONSOLE_TIME	display time/date info in
684						upper right corner
685						(requires CONFIG_CMD_DATE)
686			CONFIG_VIDEO_LOGO	display Linux logo in
687						upper left corner
688			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
689						linux_logo.h for logo.
690						Requires CONFIG_VIDEO_LOGO
691			CONFIG_CONSOLE_EXTRA_INFO
692						additional board info beside
693						the logo
694
695		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
696		a limited number of ANSI escape sequences (cursor control,
697		erase functions and limited graphics rendition control).
698
699		When CONFIG_CFB_CONSOLE is defined, video console is
700		default i/o. Serial console can be forced with
701		environment 'console=serial'.
702
703		When CONFIG_SILENT_CONSOLE is defined, all console
704		messages (by U-Boot and Linux!) can be silenced with
705		the "silent" environment variable. See
706		doc/README.silent for more information.
707
708		CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default
709			is 0x00.
710		CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default
711			is 0xa0.
712
713- Console Baudrate:
714		CONFIG_BAUDRATE - in bps
715		Select one of the baudrates listed in
716		CONFIG_SYS_BAUDRATE_TABLE, see below.
717		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
718
719- Console Rx buffer length
720		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
721		the maximum receive buffer length for the SMC.
722		This option is actual only for 82xx and 8xx possible.
723		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
724		must be defined, to setup the maximum idle timeout for
725		the SMC.
726
727- Pre-Console Buffer:
728		Prior to the console being initialised (i.e. serial UART
729		initialised etc) all console output is silently discarded.
730		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
731		buffer any console messages prior to the console being
732		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
733		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
734		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
735		bytes are output before the console is initialised, the
736		earlier bytes are discarded.
737
738		'Sane' compilers will generate smaller code if
739		CONFIG_PRE_CON_BUF_SZ is a power of 2
740
741- Safe printf() functions
742		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
743		the printf() functions. These are defined in
744		include/vsprintf.h and include snprintf(), vsnprintf() and
745		so on. Code size increase is approximately 300-500 bytes.
746		If this option is not given then these functions will
747		silently discard their buffer size argument - this means
748		you are not getting any overflow checking in this case.
749
750- Boot Delay:	CONFIG_BOOTDELAY - in seconds
751		Delay before automatically booting the default image;
752		set to -1 to disable autoboot.
753		set to -2 to autoboot with no delay and not check for abort
754		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
755
756		See doc/README.autoboot for these options that
757		work with CONFIG_BOOTDELAY. None are required.
758		CONFIG_BOOT_RETRY_TIME
759		CONFIG_BOOT_RETRY_MIN
760		CONFIG_AUTOBOOT_KEYED
761		CONFIG_AUTOBOOT_PROMPT
762		CONFIG_AUTOBOOT_DELAY_STR
763		CONFIG_AUTOBOOT_STOP_STR
764		CONFIG_AUTOBOOT_DELAY_STR2
765		CONFIG_AUTOBOOT_STOP_STR2
766		CONFIG_ZERO_BOOTDELAY_CHECK
767		CONFIG_RESET_TO_RETRY
768
769- Autoboot Command:
770		CONFIG_BOOTCOMMAND
771		Only needed when CONFIG_BOOTDELAY is enabled;
772		define a command string that is automatically executed
773		when no character is read on the console interface
774		within "Boot Delay" after reset.
775
776		CONFIG_BOOTARGS
777		This can be used to pass arguments to the bootm
778		command. The value of CONFIG_BOOTARGS goes into the
779		environment value "bootargs".
780
781		CONFIG_RAMBOOT and CONFIG_NFSBOOT
782		The value of these goes into the environment as
783		"ramboot" and "nfsboot" respectively, and can be used
784		as a convenience, when switching between booting from
785		RAM and NFS.
786
787- Pre-Boot Commands:
788		CONFIG_PREBOOT
789
790		When this option is #defined, the existence of the
791		environment variable "preboot" will be checked
792		immediately before starting the CONFIG_BOOTDELAY
793		countdown and/or running the auto-boot command resp.
794		entering interactive mode.
795
796		This feature is especially useful when "preboot" is
797		automatically generated or modified. For an example
798		see the LWMON board specific code: here "preboot" is
799		modified when the user holds down a certain
800		combination of keys on the (special) keyboard when
801		booting the systems
802
803- Serial Download Echo Mode:
804		CONFIG_LOADS_ECHO
805		If defined to 1, all characters received during a
806		serial download (using the "loads" command) are
807		echoed back. This might be needed by some terminal
808		emulations (like "cu"), but may as well just take
809		time on others. This setting #define's the initial
810		value of the "loads_echo" environment variable.
811
812- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
813		CONFIG_KGDB_BAUDRATE
814		Select one of the baudrates listed in
815		CONFIG_SYS_BAUDRATE_TABLE, see below.
816
817- Monitor Functions:
818		Monitor commands can be included or excluded
819		from the build by using the #include files
820		<config_cmd_all.h> and #undef'ing unwanted
821		commands, or using <config_cmd_default.h>
822		and augmenting with additional #define's
823		for wanted commands.
824
825		The default command configuration includes all commands
826		except those marked below with a "*".
827
828		CONFIG_CMD_ASKENV	* ask for env variable
829		CONFIG_CMD_BDI		  bdinfo
830		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
831		CONFIG_CMD_BMP		* BMP support
832		CONFIG_CMD_BSP		* Board specific commands
833		CONFIG_CMD_BOOTD	  bootd
834		CONFIG_CMD_CACHE	* icache, dcache
835		CONFIG_CMD_CONSOLE	  coninfo
836		CONFIG_CMD_CRC32	* crc32
837		CONFIG_CMD_DATE		* support for RTC, date/time...
838		CONFIG_CMD_DHCP		* DHCP support
839		CONFIG_CMD_DIAG		* Diagnostics
840		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
841		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
842		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
843		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
844		CONFIG_CMD_DTT		* Digital Therm and Thermostat
845		CONFIG_CMD_ECHO		  echo arguments
846		CONFIG_CMD_EDITENV	  edit env variable
847		CONFIG_CMD_EEPROM	* EEPROM read/write support
848		CONFIG_CMD_ELF		* bootelf, bootvx
849		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
850		CONFIG_CMD_ENV_FLAGS	* display details about env flags
851		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
852		CONFIG_CMD_EXPORTENV	* export the environment
853		CONFIG_CMD_EXT2		* ext2 command support
854		CONFIG_CMD_EXT4		* ext4 command support
855		CONFIG_CMD_SAVEENV	  saveenv
856		CONFIG_CMD_FDC		* Floppy Disk Support
857		CONFIG_CMD_FAT		* FAT command support
858		CONFIG_CMD_FDOS		* Dos diskette Support
859		CONFIG_CMD_FLASH	  flinfo, erase, protect
860		CONFIG_CMD_FPGA		  FPGA device initialization support
861		CONFIG_CMD_FUSE		* Device fuse support
862		CONFIG_CMD_GETTIME	* Get time since boot
863		CONFIG_CMD_GO		* the 'go' command (exec code)
864		CONFIG_CMD_GREPENV	* search environment
865		CONFIG_CMD_HASH		* calculate hash / digest
866		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
867		CONFIG_CMD_I2C		* I2C serial bus support
868		CONFIG_CMD_IDE		* IDE harddisk support
869		CONFIG_CMD_IMI		  iminfo
870		CONFIG_CMD_IMLS		  List all images found in NOR flash
871		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
872		CONFIG_CMD_IMMAP	* IMMR dump support
873		CONFIG_CMD_IMPORTENV	* import an environment
874		CONFIG_CMD_INI		* import data from an ini file into the env
875		CONFIG_CMD_IRQ		* irqinfo
876		CONFIG_CMD_ITEST	  Integer/string test of 2 values
877		CONFIG_CMD_JFFS2	* JFFS2 Support
878		CONFIG_CMD_KGDB		* kgdb
879		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
880		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
881					  (169.254.*.*)
882		CONFIG_CMD_LOADB	  loadb
883		CONFIG_CMD_LOADS	  loads
884		CONFIG_CMD_MD5SUM	* print md5 message digest
885					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
886		CONFIG_CMD_MEMINFO	* Display detailed memory information
887		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
888					  loop, loopw
889		CONFIG_CMD_MEMTEST	* mtest
890		CONFIG_CMD_MISC		  Misc functions like sleep etc
891		CONFIG_CMD_MMC		* MMC memory mapped support
892		CONFIG_CMD_MII		* MII utility commands
893		CONFIG_CMD_MTDPARTS	* MTD partition support
894		CONFIG_CMD_NAND		* NAND support
895		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
896		CONFIG_CMD_NFS		  NFS support
897		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
898		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
899		CONFIG_CMD_PCI		* pciinfo
900		CONFIG_CMD_PCMCIA		* PCMCIA support
901		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
902					  host
903		CONFIG_CMD_PORTIO	* Port I/O
904		CONFIG_CMD_READ		* Read raw data from partition
905		CONFIG_CMD_REGINFO	* Register dump
906		CONFIG_CMD_RUN		  run command in env variable
907		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
908		CONFIG_CMD_SAVES	* save S record dump
909		CONFIG_CMD_SCSI		* SCSI Support
910		CONFIG_CMD_SDRAM	* print SDRAM configuration information
911					  (requires CONFIG_CMD_I2C)
912		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
913					  (4xx only)
914		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
915		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
916					  (requires CONFIG_CMD_MEMORY)
917		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
918		CONFIG_CMD_SOURCE	  "source" command Support
919		CONFIG_CMD_SPI		* SPI serial bus support
920		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
921		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
922		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
923		CONFIG_CMD_TIMER	* access to the system tick timer
924		CONFIG_CMD_USB		* USB support
925		CONFIG_CMD_CDP		* Cisco Discover Protocol support
926		CONFIG_CMD_MFSL		* Microblaze FSL support
927		CONFIG_CMD_XIMG		  Load part of Multi Image
928
929
930		EXAMPLE: If you want all functions except of network
931		support you can write:
932
933		#include "config_cmd_all.h"
934		#undef CONFIG_CMD_NET
935
936	Other Commands:
937		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
938
939	Note:	Don't enable the "icache" and "dcache" commands
940		(configuration option CONFIG_CMD_CACHE) unless you know
941		what you (and your U-Boot users) are doing. Data
942		cache cannot be enabled on systems like the 8xx or
943		8260 (where accesses to the IMMR region must be
944		uncached), and it cannot be disabled on all other
945		systems where we (mis-) use the data cache to hold an
946		initial stack and some data.
947
948
949		XXX - this list needs to get updated!
950
951- Regular expression support:
952		CONFIG_REGEX
953		If this variable is defined, U-Boot is linked against
954		the SLRE (Super Light Regular Expression) library,
955		which adds regex support to some commands, as for
956		example "env grep" and "setexpr".
957
958- Device tree:
959		CONFIG_OF_CONTROL
960		If this variable is defined, U-Boot will use a device tree
961		to configure its devices, instead of relying on statically
962		compiled #defines in the board file. This option is
963		experimental and only available on a few boards. The device
964		tree is available in the global data as gd->fdt_blob.
965
966		U-Boot needs to get its device tree from somewhere. This can
967		be done using one of the two options below:
968
969		CONFIG_OF_EMBED
970		If this variable is defined, U-Boot will embed a device tree
971		binary in its image. This device tree file should be in the
972		board directory and called <soc>-<board>.dts. The binary file
973		is then picked up in board_init_f() and made available through
974		the global data structure as gd->blob.
975
976		CONFIG_OF_SEPARATE
977		If this variable is defined, U-Boot will build a device tree
978		binary. It will be called u-boot.dtb. Architecture-specific
979		code will locate it at run-time. Generally this works by:
980
981			cat u-boot.bin u-boot.dtb >image.bin
982
983		and in fact, U-Boot does this for you, creating a file called
984		u-boot-dtb.bin which is useful in the common case. You can
985		still use the individual files if you need something more
986		exotic.
987
988- Watchdog:
989		CONFIG_WATCHDOG
990		If this variable is defined, it enables watchdog
991		support for the SoC. There must be support in the SoC
992		specific code for a watchdog. For the 8xx and 8260
993		CPUs, the SIU Watchdog feature is enabled in the SYPCR
994		register.  When supported for a specific SoC is
995		available, then no further board specific code should
996		be needed to use it.
997
998		CONFIG_HW_WATCHDOG
999		When using a watchdog circuitry external to the used
1000		SoC, then define this variable and provide board
1001		specific code for the "hw_watchdog_reset" function.
1002
1003- U-Boot Version:
1004		CONFIG_VERSION_VARIABLE
1005		If this variable is defined, an environment variable
1006		named "ver" is created by U-Boot showing the U-Boot
1007		version as printed by the "version" command.
1008		Any change to this variable will be reverted at the
1009		next reset.
1010
1011- Real-Time Clock:
1012
1013		When CONFIG_CMD_DATE is selected, the type of the RTC
1014		has to be selected, too. Define exactly one of the
1015		following options:
1016
1017		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1018		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1019		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1020		CONFIG_RTC_MC146818	- use MC146818 RTC
1021		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1022		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1023		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1024		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1025		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1026		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1027		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1028		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1029					  RV3029 RTC.
1030
1031		Note that if the RTC uses I2C, then the I2C interface
1032		must also be configured. See I2C Support, below.
1033
1034- GPIO Support:
1035		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1036		CONFIG_PCA953X_INFO	- enable pca953x info command
1037
1038		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1039		chip-ngpio pairs that tell the PCA953X driver the number of
1040		pins supported by a particular chip.
1041
1042		Note that if the GPIO device uses I2C, then the I2C interface
1043		must also be configured. See I2C Support, below.
1044
1045- Timestamp Support:
1046
1047		When CONFIG_TIMESTAMP is selected, the timestamp
1048		(date and time) of an image is printed by image
1049		commands like bootm or iminfo. This option is
1050		automatically enabled when you select CONFIG_CMD_DATE .
1051
1052- Partition Labels (disklabels) Supported:
1053		Zero or more of the following:
1054		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1055		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1056				       Intel architecture, USB sticks, etc.
1057		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1058		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1059				       bootloader.  Note 2TB partition limit; see
1060				       disk/part_efi.c
1061		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1062
1063		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1064		CONFIG_CMD_SCSI) you must configure support for at
1065		least one non-MTD partition type as well.
1066
1067- IDE Reset method:
1068		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1069		board configurations files but used nowhere!
1070
1071		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1072		be performed by calling the function
1073			ide_set_reset(int reset)
1074		which has to be defined in a board specific file
1075
1076- ATAPI Support:
1077		CONFIG_ATAPI
1078
1079		Set this to enable ATAPI support.
1080
1081- LBA48 Support
1082		CONFIG_LBA48
1083
1084		Set this to enable support for disks larger than 137GB
1085		Also look at CONFIG_SYS_64BIT_LBA.
1086		Whithout these , LBA48 support uses 32bit variables and will 'only'
1087		support disks up to 2.1TB.
1088
1089		CONFIG_SYS_64BIT_LBA:
1090			When enabled, makes the IDE subsystem use 64bit sector addresses.
1091			Default is 32bit.
1092
1093- SCSI Support:
1094		At the moment only there is only support for the
1095		SYM53C8XX SCSI controller; define
1096		CONFIG_SCSI_SYM53C8XX to enable it.
1097
1098		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1099		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1100		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1101		maximum numbers of LUNs, SCSI ID's and target
1102		devices.
1103		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1104
1105		The environment variable 'scsidevs' is set to the number of
1106		SCSI devices found during the last scan.
1107
1108- NETWORK Support (PCI):
1109		CONFIG_E1000
1110		Support for Intel 8254x/8257x gigabit chips.
1111
1112		CONFIG_E1000_SPI
1113		Utility code for direct access to the SPI bus on Intel 8257x.
1114		This does not do anything useful unless you set at least one
1115		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1116
1117		CONFIG_E1000_SPI_GENERIC
1118		Allow generic access to the SPI bus on the Intel 8257x, for
1119		example with the "sspi" command.
1120
1121		CONFIG_CMD_E1000
1122		Management command for E1000 devices.  When used on devices
1123		with SPI support you can reprogram the EEPROM from U-Boot.
1124
1125		CONFIG_E1000_FALLBACK_MAC
1126		default MAC for empty EEPROM after production.
1127
1128		CONFIG_EEPRO100
1129		Support for Intel 82557/82559/82559ER chips.
1130		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1131		write routine for first time initialisation.
1132
1133		CONFIG_TULIP
1134		Support for Digital 2114x chips.
1135		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1136		modem chip initialisation (KS8761/QS6611).
1137
1138		CONFIG_NATSEMI
1139		Support for National dp83815 chips.
1140
1141		CONFIG_NS8382X
1142		Support for National dp8382[01] gigabit chips.
1143
1144- NETWORK Support (other):
1145
1146		CONFIG_DRIVER_AT91EMAC
1147		Support for AT91RM9200 EMAC.
1148
1149			CONFIG_RMII
1150			Define this to use reduced MII inteface
1151
1152			CONFIG_DRIVER_AT91EMAC_QUIET
1153			If this defined, the driver is quiet.
1154			The driver doen't show link status messages.
1155
1156		CONFIG_CALXEDA_XGMAC
1157		Support for the Calxeda XGMAC device
1158
1159		CONFIG_LAN91C96
1160		Support for SMSC's LAN91C96 chips.
1161
1162			CONFIG_LAN91C96_BASE
1163			Define this to hold the physical address
1164			of the LAN91C96's I/O space
1165
1166			CONFIG_LAN91C96_USE_32_BIT
1167			Define this to enable 32 bit addressing
1168
1169		CONFIG_SMC91111
1170		Support for SMSC's LAN91C111 chip
1171
1172			CONFIG_SMC91111_BASE
1173			Define this to hold the physical address
1174			of the device (I/O space)
1175
1176			CONFIG_SMC_USE_32_BIT
1177			Define this if data bus is 32 bits
1178
1179			CONFIG_SMC_USE_IOFUNCS
1180			Define this to use i/o functions instead of macros
1181			(some hardware wont work with macros)
1182
1183		CONFIG_DRIVER_TI_EMAC
1184		Support for davinci emac
1185
1186			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1187			Define this if you have more then 3 PHYs.
1188
1189		CONFIG_FTGMAC100
1190		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1191
1192			CONFIG_FTGMAC100_EGIGA
1193			Define this to use GE link update with gigabit PHY.
1194			Define this if FTGMAC100 is connected to gigabit PHY.
1195			If your system has 10/100 PHY only, it might not occur
1196			wrong behavior. Because PHY usually return timeout or
1197			useless data when polling gigabit status and gigabit
1198			control registers. This behavior won't affect the
1199			correctnessof 10/100 link speed update.
1200
1201		CONFIG_SMC911X
1202		Support for SMSC's LAN911x and LAN921x chips
1203
1204			CONFIG_SMC911X_BASE
1205			Define this to hold the physical address
1206			of the device (I/O space)
1207
1208			CONFIG_SMC911X_32_BIT
1209			Define this if data bus is 32 bits
1210
1211			CONFIG_SMC911X_16_BIT
1212			Define this if data bus is 16 bits. If your processor
1213			automatically converts one 32 bit word to two 16 bit
1214			words you may also try CONFIG_SMC911X_32_BIT.
1215
1216		CONFIG_SH_ETHER
1217		Support for Renesas on-chip Ethernet controller
1218
1219			CONFIG_SH_ETHER_USE_PORT
1220			Define the number of ports to be used
1221
1222			CONFIG_SH_ETHER_PHY_ADDR
1223			Define the ETH PHY's address
1224
1225			CONFIG_SH_ETHER_CACHE_WRITEBACK
1226			If this option is set, the driver enables cache flush.
1227
1228- TPM Support:
1229		CONFIG_TPM
1230		Support TPM devices.
1231
1232		CONFIG_TPM_TIS_I2C
1233		Support for i2c bus TPM devices. Only one device
1234		per system is supported at this time.
1235
1236			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1237			Define the the i2c bus number for the TPM device
1238
1239			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1240			Define the TPM's address on the i2c bus
1241
1242			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1243			Define the burst count bytes upper limit
1244
1245		CONFIG_TPM_ATMEL_TWI
1246		Support for Atmel TWI TPM device. Requires I2C support.
1247
1248		CONFIG_TPM_TIS_LPC
1249		Support for generic parallel port TPM devices. Only one device
1250		per system is supported at this time.
1251
1252			CONFIG_TPM_TIS_BASE_ADDRESS
1253			Base address where the generic TPM device is mapped
1254			to. Contemporary x86 systems usually map it at
1255			0xfed40000.
1256
1257		CONFIG_CMD_TPM
1258		Add tpm monitor functions.
1259		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1260		provides monitor access to authorized functions.
1261
1262		CONFIG_TPM
1263		Define this to enable the TPM support library which provides
1264		functional interfaces to some TPM commands.
1265		Requires support for a TPM device.
1266
1267		CONFIG_TPM_AUTH_SESSIONS
1268		Define this to enable authorized functions in the TPM library.
1269		Requires CONFIG_TPM and CONFIG_SHA1.
1270
1271- USB Support:
1272		At the moment only the UHCI host controller is
1273		supported (PIP405, MIP405, MPC5200); define
1274		CONFIG_USB_UHCI to enable it.
1275		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1276		and define CONFIG_USB_STORAGE to enable the USB
1277		storage devices.
1278		Note:
1279		Supported are USB Keyboards and USB Floppy drives
1280		(TEAC FD-05PUB).
1281		MPC5200 USB requires additional defines:
1282			CONFIG_USB_CLOCK
1283				for 528 MHz Clock: 0x0001bbbb
1284			CONFIG_PSC3_USB
1285				for USB on PSC3
1286			CONFIG_USB_CONFIG
1287				for differential drivers: 0x00001000
1288				for single ended drivers: 0x00005000
1289				for differential drivers on PSC3: 0x00000100
1290				for single ended drivers on PSC3: 0x00004100
1291			CONFIG_SYS_USB_EVENT_POLL
1292				May be defined to allow interrupt polling
1293				instead of using asynchronous interrupts
1294
1295		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1296		txfilltuning field in the EHCI controller on reset.
1297
1298		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1299		interval for usb hub power-on delay.(minimum 100msec)
1300
1301- USB Device:
1302		Define the below if you wish to use the USB console.
1303		Once firmware is rebuilt from a serial console issue the
1304		command "setenv stdin usbtty; setenv stdout usbtty" and
1305		attach your USB cable. The Unix command "dmesg" should print
1306		it has found a new device. The environment variable usbtty
1307		can be set to gserial or cdc_acm to enable your device to
1308		appear to a USB host as a Linux gserial device or a
1309		Common Device Class Abstract Control Model serial device.
1310		If you select usbtty = gserial you should be able to enumerate
1311		a Linux host by
1312		# modprobe usbserial vendor=0xVendorID product=0xProductID
1313		else if using cdc_acm, simply setting the environment
1314		variable usbtty to be cdc_acm should suffice. The following
1315		might be defined in YourBoardName.h
1316
1317			CONFIG_USB_DEVICE
1318			Define this to build a UDC device
1319
1320			CONFIG_USB_TTY
1321			Define this to have a tty type of device available to
1322			talk to the UDC device
1323
1324			CONFIG_USBD_HS
1325			Define this to enable the high speed support for usb
1326			device and usbtty. If this feature is enabled, a routine
1327			int is_usbd_high_speed(void)
1328			also needs to be defined by the driver to dynamically poll
1329			whether the enumeration has succeded at high speed or full
1330			speed.
1331
1332			CONFIG_SYS_CONSOLE_IS_IN_ENV
1333			Define this if you want stdin, stdout &/or stderr to
1334			be set to usbtty.
1335
1336			mpc8xx:
1337				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1338				Derive USB clock from external clock "blah"
1339				- CONFIG_SYS_USB_EXTC_CLK 0x02
1340
1341				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1342				Derive USB clock from brgclk
1343				- CONFIG_SYS_USB_BRG_CLK 0x04
1344
1345		If you have a USB-IF assigned VendorID then you may wish to
1346		define your own vendor specific values either in BoardName.h
1347		or directly in usbd_vendor_info.h. If you don't define
1348		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1349		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1350		should pretend to be a Linux device to it's target host.
1351
1352			CONFIG_USBD_MANUFACTURER
1353			Define this string as the name of your company for
1354			- CONFIG_USBD_MANUFACTURER "my company"
1355
1356			CONFIG_USBD_PRODUCT_NAME
1357			Define this string as the name of your product
1358			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1359
1360			CONFIG_USBD_VENDORID
1361			Define this as your assigned Vendor ID from the USB
1362			Implementors Forum. This *must* be a genuine Vendor ID
1363			to avoid polluting the USB namespace.
1364			- CONFIG_USBD_VENDORID 0xFFFF
1365
1366			CONFIG_USBD_PRODUCTID
1367			Define this as the unique Product ID
1368			for your device
1369			- CONFIG_USBD_PRODUCTID 0xFFFF
1370
1371- ULPI Layer Support:
1372		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1373		the generic ULPI layer. The generic layer accesses the ULPI PHY
1374		via the platform viewport, so you need both the genric layer and
1375		the viewport enabled. Currently only Chipidea/ARC based
1376		viewport is supported.
1377		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1378		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1379		If your ULPI phy needs a different reference clock than the
1380		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1381		the appropriate value in Hz.
1382
1383- MMC Support:
1384		The MMC controller on the Intel PXA is supported. To
1385		enable this define CONFIG_MMC. The MMC can be
1386		accessed from the boot prompt by mapping the device
1387		to physical memory similar to flash. Command line is
1388		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1389		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1390
1391		CONFIG_SH_MMCIF
1392		Support for Renesas on-chip MMCIF controller
1393
1394			CONFIG_SH_MMCIF_ADDR
1395			Define the base address of MMCIF registers
1396
1397			CONFIG_SH_MMCIF_CLK
1398			Define the clock frequency for MMCIF
1399
1400- USB Device Firmware Update (DFU) class support:
1401		CONFIG_DFU_FUNCTION
1402		This enables the USB portion of the DFU USB class
1403
1404		CONFIG_CMD_DFU
1405		This enables the command "dfu" which is used to have
1406		U-Boot create a DFU class device via USB.  This command
1407		requires that the "dfu_alt_info" environment variable be
1408		set and define the alt settings to expose to the host.
1409
1410		CONFIG_DFU_MMC
1411		This enables support for exposing (e)MMC devices via DFU.
1412
1413		CONFIG_DFU_NAND
1414		This enables support for exposing NAND devices via DFU.
1415
1416		CONFIG_DFU_RAM
1417		This enables support for exposing RAM via DFU.
1418		Note: DFU spec refer to non-volatile memory usage, but
1419		allow usages beyond the scope of spec - here RAM usage,
1420		one that would help mostly the developer.
1421
1422		CONFIG_SYS_DFU_DATA_BUF_SIZE
1423		Dfu transfer uses a buffer before writing data to the
1424		raw storage device. Make the size (in bytes) of this buffer
1425		configurable. The size of this buffer is also configurable
1426		through the "dfu_bufsiz" environment variable.
1427
1428		CONFIG_SYS_DFU_MAX_FILE_SIZE
1429		When updating files rather than the raw storage device,
1430		we use a static buffer to copy the file into and then write
1431		the buffer once we've been given the whole file.  Define
1432		this to the maximum filesize (in bytes) for the buffer.
1433		Default is 4 MiB if undefined.
1434
1435- Journaling Flash filesystem support:
1436		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1437		CONFIG_JFFS2_NAND_DEV
1438		Define these for a default partition on a NAND device
1439
1440		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1441		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1442		Define these for a default partition on a NOR device
1443
1444		CONFIG_SYS_JFFS_CUSTOM_PART
1445		Define this to create an own partition. You have to provide a
1446		function struct part_info* jffs2_part_info(int part_num)
1447
1448		If you define only one JFFS2 partition you may also want to
1449		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1450		to disable the command chpart. This is the default when you
1451		have not defined a custom partition
1452
1453- FAT(File Allocation Table) filesystem write function support:
1454		CONFIG_FAT_WRITE
1455
1456		Define this to enable support for saving memory data as a
1457		file in FAT formatted partition.
1458
1459		This will also enable the command "fatwrite" enabling the
1460		user to write files to FAT.
1461
1462CBFS (Coreboot Filesystem) support
1463		CONFIG_CMD_CBFS
1464
1465		Define this to enable support for reading from a Coreboot
1466		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1467		and cbfsload.
1468
1469- Keyboard Support:
1470		CONFIG_ISA_KEYBOARD
1471
1472		Define this to enable standard (PC-Style) keyboard
1473		support
1474
1475		CONFIG_I8042_KBD
1476		Standard PC keyboard driver with US (is default) and
1477		GERMAN key layout (switch via environment 'keymap=de') support.
1478		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1479		for cfb_console. Supports cursor blinking.
1480
1481		CONFIG_CROS_EC_KEYB
1482		Enables a Chrome OS keyboard using the CROS_EC interface.
1483		This uses CROS_EC to communicate with a second microcontroller
1484		which provides key scans on request.
1485
1486- Video support:
1487		CONFIG_VIDEO
1488
1489		Define this to enable video support (for output to
1490		video).
1491
1492		CONFIG_VIDEO_CT69000
1493
1494		Enable Chips & Technologies 69000 Video chip
1495
1496		CONFIG_VIDEO_SMI_LYNXEM
1497		Enable Silicon Motion SMI 712/710/810 Video chip. The
1498		video output is selected via environment 'videoout'
1499		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1500		assumed.
1501
1502		For the CT69000 and SMI_LYNXEM drivers, videomode is
1503		selected via environment 'videomode'. Two different ways
1504		are possible:
1505		- "videomode=num"   'num' is a standard LiLo mode numbers.
1506		Following standard modes are supported	(* is default):
1507
1508		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1509		-------------+---------------------------------------------
1510		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1511		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1512		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1513		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1514		-------------+---------------------------------------------
1515		(i.e. setenv videomode 317; saveenv; reset;)
1516
1517		- "videomode=bootargs" all the video parameters are parsed
1518		from the bootargs. (See drivers/video/videomodes.c)
1519
1520
1521		CONFIG_VIDEO_SED13806
1522		Enable Epson SED13806 driver. This driver supports 8bpp
1523		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1524		or CONFIG_VIDEO_SED13806_16BPP
1525
1526		CONFIG_FSL_DIU_FB
1527		Enable the Freescale DIU video driver.	Reference boards for
1528		SOCs that have a DIU should define this macro to enable DIU
1529		support, and should also define these other macros:
1530
1531			CONFIG_SYS_DIU_ADDR
1532			CONFIG_VIDEO
1533			CONFIG_CMD_BMP
1534			CONFIG_CFB_CONSOLE
1535			CONFIG_VIDEO_SW_CURSOR
1536			CONFIG_VGA_AS_SINGLE_DEVICE
1537			CONFIG_VIDEO_LOGO
1538			CONFIG_VIDEO_BMP_LOGO
1539
1540		The DIU driver will look for the 'video-mode' environment
1541		variable, and if defined, enable the DIU as a console during
1542		boot.  See the documentation file README.video for a
1543		description of this variable.
1544
1545		CONFIG_VIDEO_VGA
1546
1547		Enable the VGA video / BIOS for x86. The alternative if you
1548		are using coreboot is to use the coreboot frame buffer
1549		driver.
1550
1551
1552- Keyboard Support:
1553		CONFIG_KEYBOARD
1554
1555		Define this to enable a custom keyboard support.
1556		This simply calls drv_keyboard_init() which must be
1557		defined in your board-specific files.
1558		The only board using this so far is RBC823.
1559
1560- LCD Support:	CONFIG_LCD
1561
1562		Define this to enable LCD support (for output to LCD
1563		display); also select one of the supported displays
1564		by defining one of these:
1565
1566		CONFIG_ATMEL_LCD:
1567
1568			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1569
1570		CONFIG_NEC_NL6448AC33:
1571
1572			NEC NL6448AC33-18. Active, color, single scan.
1573
1574		CONFIG_NEC_NL6448BC20
1575
1576			NEC NL6448BC20-08. 6.5", 640x480.
1577			Active, color, single scan.
1578
1579		CONFIG_NEC_NL6448BC33_54
1580
1581			NEC NL6448BC33-54. 10.4", 640x480.
1582			Active, color, single scan.
1583
1584		CONFIG_SHARP_16x9
1585
1586			Sharp 320x240. Active, color, single scan.
1587			It isn't 16x9, and I am not sure what it is.
1588
1589		CONFIG_SHARP_LQ64D341
1590
1591			Sharp LQ64D341 display, 640x480.
1592			Active, color, single scan.
1593
1594		CONFIG_HLD1045
1595
1596			HLD1045 display, 640x480.
1597			Active, color, single scan.
1598
1599		CONFIG_OPTREX_BW
1600
1601			Optrex	 CBL50840-2 NF-FW 99 22 M5
1602			or
1603			Hitachi	 LMG6912RPFC-00T
1604			or
1605			Hitachi	 SP14Q002
1606
1607			320x240. Black & white.
1608
1609		Normally display is black on white background; define
1610		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1611
1612		CONFIG_LCD_ALIGNMENT
1613
1614		Normally the LCD is page-aligned (tyically 4KB). If this is
1615		defined then the LCD will be aligned to this value instead.
1616		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1617		here, since it is cheaper to change data cache settings on
1618		a per-section basis.
1619
1620		CONFIG_CONSOLE_SCROLL_LINES
1621
1622		When the console need to be scrolled, this is the number of
1623		lines to scroll by. It defaults to 1. Increasing this makes
1624		the console jump but can help speed up operation when scrolling
1625		is slow.
1626
1627		CONFIG_LCD_BMP_RLE8
1628
1629		Support drawing of RLE8-compressed bitmaps on the LCD.
1630
1631		CONFIG_I2C_EDID
1632
1633		Enables an 'i2c edid' command which can read EDID
1634		information over I2C from an attached LCD display.
1635
1636- Splash Screen Support: CONFIG_SPLASH_SCREEN
1637
1638		If this option is set, the environment is checked for
1639		a variable "splashimage". If found, the usual display
1640		of logo, copyright and system information on the LCD
1641		is suppressed and the BMP image at the address
1642		specified in "splashimage" is loaded instead. The
1643		console is redirected to the "nulldev", too. This
1644		allows for a "silent" boot where a splash screen is
1645		loaded very quickly after power-on.
1646
1647		CONFIG_SPLASHIMAGE_GUARD
1648
1649		If this option is set, then U-Boot will prevent the environment
1650		variable "splashimage" from being set to a problematic address
1651		(see README.displaying-bmps and README.arm-unaligned-accesses).
1652		This option is useful for targets where, due to alignment
1653		restrictions, an improperly aligned BMP image will cause a data
1654		abort. If you think you will not have problems with unaligned
1655		accesses (for example because your toolchain prevents them)
1656		there is no need to set this option.
1657
1658		CONFIG_SPLASH_SCREEN_ALIGN
1659
1660		If this option is set the splash image can be freely positioned
1661		on the screen. Environment variable "splashpos" specifies the
1662		position as "x,y". If a positive number is given it is used as
1663		number of pixel from left/top. If a negative number is given it
1664		is used as number of pixel from right/bottom. You can also
1665		specify 'm' for centering the image.
1666
1667		Example:
1668		setenv splashpos m,m
1669			=> image at center of screen
1670
1671		setenv splashpos 30,20
1672			=> image at x = 30 and y = 20
1673
1674		setenv splashpos -10,m
1675			=> vertically centered image
1676			   at x = dspWidth - bmpWidth - 9
1677
1678- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1679
1680		If this option is set, additionally to standard BMP
1681		images, gzipped BMP images can be displayed via the
1682		splashscreen support or the bmp command.
1683
1684- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1685
1686		If this option is set, 8-bit RLE compressed BMP images
1687		can be displayed via the splashscreen support or the
1688		bmp command.
1689
1690- Do compresssing for memory range:
1691		CONFIG_CMD_ZIP
1692
1693		If this option is set, it would use zlib deflate method
1694		to compress the specified memory at its best effort.
1695
1696- Compression support:
1697		CONFIG_GZIP
1698
1699		Enabled by default to support gzip compressed images.
1700
1701		CONFIG_BZIP2
1702
1703		If this option is set, support for bzip2 compressed
1704		images is included. If not, only uncompressed and gzip
1705		compressed images are supported.
1706
1707		NOTE: the bzip2 algorithm requires a lot of RAM, so
1708		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1709		be at least 4MB.
1710
1711		CONFIG_LZMA
1712
1713		If this option is set, support for lzma compressed
1714		images is included.
1715
1716		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1717		requires an amount of dynamic memory that is given by the
1718		formula:
1719
1720			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1721
1722		Where lc and lp stand for, respectively, Literal context bits
1723		and Literal pos bits.
1724
1725		This value is upper-bounded by 14MB in the worst case. Anyway,
1726		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1727		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1728		a very small buffer.
1729
1730		Use the lzmainfo tool to determinate the lc and lp values and
1731		then calculate the amount of needed dynamic memory (ensuring
1732		the appropriate CONFIG_SYS_MALLOC_LEN value).
1733
1734		CONFIG_LZO
1735
1736		If this option is set, support for LZO compressed images
1737		is included.
1738
1739- MII/PHY support:
1740		CONFIG_PHY_ADDR
1741
1742		The address of PHY on MII bus.
1743
1744		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1745
1746		The clock frequency of the MII bus
1747
1748		CONFIG_PHY_GIGE
1749
1750		If this option is set, support for speed/duplex
1751		detection of gigabit PHY is included.
1752
1753		CONFIG_PHY_RESET_DELAY
1754
1755		Some PHY like Intel LXT971A need extra delay after
1756		reset before any MII register access is possible.
1757		For such PHY, set this option to the usec delay
1758		required. (minimum 300usec for LXT971A)
1759
1760		CONFIG_PHY_CMD_DELAY (ppc4xx)
1761
1762		Some PHY like Intel LXT971A need extra delay after
1763		command issued before MII status register can be read
1764
1765- Ethernet address:
1766		CONFIG_ETHADDR
1767		CONFIG_ETH1ADDR
1768		CONFIG_ETH2ADDR
1769		CONFIG_ETH3ADDR
1770		CONFIG_ETH4ADDR
1771		CONFIG_ETH5ADDR
1772
1773		Define a default value for Ethernet address to use
1774		for the respective Ethernet interface, in case this
1775		is not determined automatically.
1776
1777- IP address:
1778		CONFIG_IPADDR
1779
1780		Define a default value for the IP address to use for
1781		the default Ethernet interface, in case this is not
1782		determined through e.g. bootp.
1783		(Environment variable "ipaddr")
1784
1785- Server IP address:
1786		CONFIG_SERVERIP
1787
1788		Defines a default value for the IP address of a TFTP
1789		server to contact when using the "tftboot" command.
1790		(Environment variable "serverip")
1791
1792		CONFIG_KEEP_SERVERADDR
1793
1794		Keeps the server's MAC address, in the env 'serveraddr'
1795		for passing to bootargs (like Linux's netconsole option)
1796
1797- Gateway IP address:
1798		CONFIG_GATEWAYIP
1799
1800		Defines a default value for the IP address of the
1801		default router where packets to other networks are
1802		sent to.
1803		(Environment variable "gatewayip")
1804
1805- Subnet mask:
1806		CONFIG_NETMASK
1807
1808		Defines a default value for the subnet mask (or
1809		routing prefix) which is used to determine if an IP
1810		address belongs to the local subnet or needs to be
1811		forwarded through a router.
1812		(Environment variable "netmask")
1813
1814- Multicast TFTP Mode:
1815		CONFIG_MCAST_TFTP
1816
1817		Defines whether you want to support multicast TFTP as per
1818		rfc-2090; for example to work with atftp.  Lets lots of targets
1819		tftp down the same boot image concurrently.  Note: the Ethernet
1820		driver in use must provide a function: mcast() to join/leave a
1821		multicast group.
1822
1823- BOOTP Recovery Mode:
1824		CONFIG_BOOTP_RANDOM_DELAY
1825
1826		If you have many targets in a network that try to
1827		boot using BOOTP, you may want to avoid that all
1828		systems send out BOOTP requests at precisely the same
1829		moment (which would happen for instance at recovery
1830		from a power failure, when all systems will try to
1831		boot, thus flooding the BOOTP server. Defining
1832		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1833		inserted before sending out BOOTP requests. The
1834		following delays are inserted then:
1835
1836		1st BOOTP request:	delay 0 ... 1 sec
1837		2nd BOOTP request:	delay 0 ... 2 sec
1838		3rd BOOTP request:	delay 0 ... 4 sec
1839		4th and following
1840		BOOTP requests:		delay 0 ... 8 sec
1841
1842- DHCP Advanced Options:
1843		You can fine tune the DHCP functionality by defining
1844		CONFIG_BOOTP_* symbols:
1845
1846		CONFIG_BOOTP_SUBNETMASK
1847		CONFIG_BOOTP_GATEWAY
1848		CONFIG_BOOTP_HOSTNAME
1849		CONFIG_BOOTP_NISDOMAIN
1850		CONFIG_BOOTP_BOOTPATH
1851		CONFIG_BOOTP_BOOTFILESIZE
1852		CONFIG_BOOTP_DNS
1853		CONFIG_BOOTP_DNS2
1854		CONFIG_BOOTP_SEND_HOSTNAME
1855		CONFIG_BOOTP_NTPSERVER
1856		CONFIG_BOOTP_TIMEOFFSET
1857		CONFIG_BOOTP_VENDOREX
1858		CONFIG_BOOTP_MAY_FAIL
1859
1860		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1861		environment variable, not the BOOTP server.
1862
1863		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1864		after the configured retry count, the call will fail
1865		instead of starting over.  This can be used to fail over
1866		to Link-local IP address configuration if the DHCP server
1867		is not available.
1868
1869		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1870		serverip from a DHCP server, it is possible that more
1871		than one DNS serverip is offered to the client.
1872		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1873		serverip will be stored in the additional environment
1874		variable "dnsip2". The first DNS serverip is always
1875		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1876		is defined.
1877
1878		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1879		to do a dynamic update of a DNS server. To do this, they
1880		need the hostname of the DHCP requester.
1881		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1882		of the "hostname" environment variable is passed as
1883		option 12 to the DHCP server.
1884
1885		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1886
1887		A 32bit value in microseconds for a delay between
1888		receiving a "DHCP Offer" and sending the "DHCP Request".
1889		This fixes a problem with certain DHCP servers that don't
1890		respond 100% of the time to a "DHCP request". E.g. On an
1891		AT91RM9200 processor running at 180MHz, this delay needed
1892		to be *at least* 15,000 usec before a Windows Server 2003
1893		DHCP server would reply 100% of the time. I recommend at
1894		least 50,000 usec to be safe. The alternative is to hope
1895		that one of the retries will be successful but note that
1896		the DHCP timeout and retry process takes a longer than
1897		this delay.
1898
1899 - Link-local IP address negotiation:
1900		Negotiate with other link-local clients on the local network
1901		for an address that doesn't require explicit configuration.
1902		This is especially useful if a DHCP server cannot be guaranteed
1903		to exist in all environments that the device must operate.
1904
1905		See doc/README.link-local for more information.
1906
1907 - CDP Options:
1908		CONFIG_CDP_DEVICE_ID
1909
1910		The device id used in CDP trigger frames.
1911
1912		CONFIG_CDP_DEVICE_ID_PREFIX
1913
1914		A two character string which is prefixed to the MAC address
1915		of the device.
1916
1917		CONFIG_CDP_PORT_ID
1918
1919		A printf format string which contains the ascii name of
1920		the port. Normally is set to "eth%d" which sets
1921		eth0 for the first Ethernet, eth1 for the second etc.
1922
1923		CONFIG_CDP_CAPABILITIES
1924
1925		A 32bit integer which indicates the device capabilities;
1926		0x00000010 for a normal host which does not forwards.
1927
1928		CONFIG_CDP_VERSION
1929
1930		An ascii string containing the version of the software.
1931
1932		CONFIG_CDP_PLATFORM
1933
1934		An ascii string containing the name of the platform.
1935
1936		CONFIG_CDP_TRIGGER
1937
1938		A 32bit integer sent on the trigger.
1939
1940		CONFIG_CDP_POWER_CONSUMPTION
1941
1942		A 16bit integer containing the power consumption of the
1943		device in .1 of milliwatts.
1944
1945		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1946
1947		A byte containing the id of the VLAN.
1948
1949- Status LED:	CONFIG_STATUS_LED
1950
1951		Several configurations allow to display the current
1952		status using a LED. For instance, the LED will blink
1953		fast while running U-Boot code, stop blinking as
1954		soon as a reply to a BOOTP request was received, and
1955		start blinking slow once the Linux kernel is running
1956		(supported by a status LED driver in the Linux
1957		kernel). Defining CONFIG_STATUS_LED enables this
1958		feature in U-Boot.
1959
1960- CAN Support:	CONFIG_CAN_DRIVER
1961
1962		Defining CONFIG_CAN_DRIVER enables CAN driver support
1963		on those systems that support this (optional)
1964		feature, like the TQM8xxL modules.
1965
1966- I2C Support:	CONFIG_SYS_I2C
1967
1968		This enable the NEW i2c subsystem, and will allow you to use
1969		i2c commands at the u-boot command line (as long as you set
1970		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1971		based realtime clock chips or other i2c devices. See
1972		common/cmd_i2c.c for a description of the command line
1973		interface.
1974
1975		ported i2c driver to the new framework:
1976		- drivers/i2c/soft_i2c.c:
1977		  - activate first bus with CONFIG_SYS_I2C_SOFT define
1978		    CONFIG_SYS_I2C_SOFT_SPEED and CONFIG_SYS_I2C_SOFT_SLAVE
1979		    for defining speed and slave address
1980		  - activate second bus with I2C_SOFT_DECLARATIONS2 define
1981		    CONFIG_SYS_I2C_SOFT_SPEED_2 and CONFIG_SYS_I2C_SOFT_SLAVE_2
1982		    for defining speed and slave address
1983		  - activate third bus with I2C_SOFT_DECLARATIONS3 define
1984		    CONFIG_SYS_I2C_SOFT_SPEED_3 and CONFIG_SYS_I2C_SOFT_SLAVE_3
1985		    for defining speed and slave address
1986		  - activate fourth bus with I2C_SOFT_DECLARATIONS4 define
1987		    CONFIG_SYS_I2C_SOFT_SPEED_4 and CONFIG_SYS_I2C_SOFT_SLAVE_4
1988		    for defining speed and slave address
1989
1990		- drivers/i2c/fsl_i2c.c:
1991		  - activate i2c driver with CONFIG_SYS_I2C_FSL
1992		    define CONFIG_SYS_FSL_I2C_OFFSET for setting the register
1993		    offset CONFIG_SYS_FSL_I2C_SPEED for the i2c speed and
1994		    CONFIG_SYS_FSL_I2C_SLAVE for the slave addr of the first
1995		    bus.
1996		  - If your board supports a second fsl i2c bus, define
1997		    CONFIG_SYS_FSL_I2C2_OFFSET for the register offset
1998		    CONFIG_SYS_FSL_I2C2_SPEED for the speed and
1999		    CONFIG_SYS_FSL_I2C2_SLAVE for the slave address of the
2000		    second bus.
2001
2002		- drivers/i2c/tegra_i2c.c:
2003		  - activate this driver with CONFIG_SYS_I2C_TEGRA
2004		  - This driver adds 4 i2c buses with a fix speed from
2005		    100000 and the slave addr 0!
2006
2007		- drivers/i2c/ppc4xx_i2c.c
2008		  - activate this driver with CONFIG_SYS_I2C_PPC4XX
2009		  - CONFIG_SYS_I2C_PPC4XX_CH0 activate hardware channel 0
2010		  - CONFIG_SYS_I2C_PPC4XX_CH1 activate hardware channel 1
2011
2012		- drivers/i2c/i2c_mxc.c
2013		  - activate this driver with CONFIG_SYS_I2C_MXC
2014		  - define speed for bus 1 with CONFIG_SYS_MXC_I2C1_SPEED
2015		  - define slave for bus 1 with CONFIG_SYS_MXC_I2C1_SLAVE
2016		  - define speed for bus 2 with CONFIG_SYS_MXC_I2C2_SPEED
2017		  - define slave for bus 2 with CONFIG_SYS_MXC_I2C2_SLAVE
2018		  - define speed for bus 3 with CONFIG_SYS_MXC_I2C3_SPEED
2019		  - define slave for bus 3 with CONFIG_SYS_MXC_I2C3_SLAVE
2020		If thoses defines are not set, default value is 100000
2021		for speed, and 0 for slave.
2022
2023		- drivers/i2c/rcar_i2c.c:
2024		  - activate this driver with CONFIG_SYS_I2C_RCAR
2025		  - This driver adds 4 i2c buses
2026
2027		  - CONFIG_SYS_RCAR_I2C0_BASE for setting the register channel 0
2028		  - CONFIG_SYS_RCAR_I2C0_SPEED for for the speed channel 0
2029		  - CONFIG_SYS_RCAR_I2C1_BASE for setting the register channel 1
2030		  - CONFIG_SYS_RCAR_I2C1_SPEED for for the speed channel 1
2031		  - CONFIG_SYS_RCAR_I2C2_BASE for setting the register channel 2
2032		  - CONFIG_SYS_RCAR_I2C2_SPEED for for the speed channel 2
2033		  - CONFIG_SYS_RCAR_I2C3_BASE for setting the register channel 3
2034		  - CONFIG_SYS_RCAR_I2C3_SPEED for for the speed channel 3
2035		  - CONFIF_SYS_RCAR_I2C_NUM_CONTROLLERS for number of i2c buses
2036
2037		additional defines:
2038
2039		CONFIG_SYS_NUM_I2C_BUSES
2040		Hold the number of i2c busses you want to use. If you
2041		don't use/have i2c muxes on your i2c bus, this
2042		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
2043		omit this define.
2044
2045		CONFIG_SYS_I2C_DIRECT_BUS
2046		define this, if you don't use i2c muxes on your hardware.
2047		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
2048		omit this define.
2049
2050		CONFIG_SYS_I2C_MAX_HOPS
2051		define how many muxes are maximal consecutively connected
2052		on one i2c bus. If you not use i2c muxes, omit this
2053		define.
2054
2055		CONFIG_SYS_I2C_BUSES
2056		hold a list of busses you want to use, only used if
2057		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
2058		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
2059		CONFIG_SYS_NUM_I2C_BUSES = 9:
2060
2061		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
2062					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
2063					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
2064					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
2065					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
2066					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
2067					{1, {I2C_NULL_HOP}}, \
2068					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
2069					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
2070					}
2071
2072		which defines
2073			bus 0 on adapter 0 without a mux
2074			bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
2075			bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
2076			bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
2077			bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
2078			bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
2079			bus 6 on adapter 1 without a mux
2080			bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
2081			bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
2082
2083		If you do not have i2c muxes on your board, omit this define.
2084
2085- Legacy I2C Support:	CONFIG_HARD_I2C
2086
2087		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2088		provides the following compelling advantages:
2089
2090		- more than one i2c adapter is usable
2091		- approved multibus support
2092		- better i2c mux support
2093
2094		** Please consider updating your I2C driver now. **
2095
2096		These enable legacy I2C serial bus commands. Defining
2097		CONFIG_HARD_I2C will include the appropriate I2C driver
2098		for the selected CPU.
2099
2100		This will allow you to use i2c commands at the u-boot
2101		command line (as long as you set CONFIG_CMD_I2C in
2102		CONFIG_COMMANDS) and communicate with i2c based realtime
2103		clock chips. See common/cmd_i2c.c for a description of the
2104		command line interface.
2105
2106		CONFIG_HARD_I2C selects a hardware I2C controller.
2107
2108		There are several other quantities that must also be
2109		defined when you define CONFIG_HARD_I2C.
2110
2111		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2112		to be the frequency (in Hz) at which you wish your i2c bus
2113		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2114		the CPU's i2c node address).
2115
2116		Now, the u-boot i2c code for the mpc8xx
2117		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2118		and so its address should therefore be cleared to 0 (See,
2119		eg, MPC823e User's Manual p.16-473). So, set
2120		CONFIG_SYS_I2C_SLAVE to 0.
2121
2122		CONFIG_SYS_I2C_INIT_MPC5XXX
2123
2124		When a board is reset during an i2c bus transfer
2125		chips might think that the current transfer is still
2126		in progress.  Reset the slave devices by sending start
2127		commands until the slave device responds.
2128
2129		That's all that's required for CONFIG_HARD_I2C.
2130
2131		If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
2132		then the following macros need to be defined (examples are
2133		from include/configs/lwmon.h):
2134
2135		I2C_INIT
2136
2137		(Optional). Any commands necessary to enable the I2C
2138		controller or configure ports.
2139
2140		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2141
2142		I2C_PORT
2143
2144		(Only for MPC8260 CPU). The I/O port to use (the code
2145		assumes both bits are on the same port). Valid values
2146		are 0..3 for ports A..D.
2147
2148		I2C_ACTIVE
2149
2150		The code necessary to make the I2C data line active
2151		(driven).  If the data line is open collector, this
2152		define can be null.
2153
2154		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2155
2156		I2C_TRISTATE
2157
2158		The code necessary to make the I2C data line tri-stated
2159		(inactive).  If the data line is open collector, this
2160		define can be null.
2161
2162		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2163
2164		I2C_READ
2165
2166		Code that returns true if the I2C data line is high,
2167		false if it is low.
2168
2169		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2170
2171		I2C_SDA(bit)
2172
2173		If <bit> is true, sets the I2C data line high. If it
2174		is false, it clears it (low).
2175
2176		eg: #define I2C_SDA(bit) \
2177			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2178			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2179
2180		I2C_SCL(bit)
2181
2182		If <bit> is true, sets the I2C clock line high. If it
2183		is false, it clears it (low).
2184
2185		eg: #define I2C_SCL(bit) \
2186			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2187			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2188
2189		I2C_DELAY
2190
2191		This delay is invoked four times per clock cycle so this
2192		controls the rate of data transfer.  The data rate thus
2193		is 1 / (I2C_DELAY * 4). Often defined to be something
2194		like:
2195
2196		#define I2C_DELAY  udelay(2)
2197
2198		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2199
2200		If your arch supports the generic GPIO framework (asm/gpio.h),
2201		then you may alternatively define the two GPIOs that are to be
2202		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2203		have GPIO-based defaults assigned to them as appropriate.
2204
2205		You should define these to the GPIO value as given directly to
2206		the generic GPIO functions.
2207
2208		CONFIG_SYS_I2C_INIT_BOARD
2209
2210		When a board is reset during an i2c bus transfer
2211		chips might think that the current transfer is still
2212		in progress. On some boards it is possible to access
2213		the i2c SCLK line directly, either by using the
2214		processor pin as a GPIO or by having a second pin
2215		connected to the bus. If this option is defined a
2216		custom i2c_init_board() routine in boards/xxx/board.c
2217		is run early in the boot sequence.
2218
2219		CONFIG_SYS_I2C_BOARD_LATE_INIT
2220
2221		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2222		defined a custom i2c_board_late_init() routine in
2223		boards/xxx/board.c is run AFTER the operations in i2c_init()
2224		is completed. This callpoint can be used to unreset i2c bus
2225		using CPU i2c controller register accesses for CPUs whose i2c
2226		controller provide such a method. It is called at the end of
2227		i2c_init() to allow i2c_init operations to setup the i2c bus
2228		controller on the CPU (e.g. setting bus speed & slave address).
2229
2230		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2231
2232		This option enables configuration of bi_iic_fast[] flags
2233		in u-boot bd_info structure based on u-boot environment
2234		variable "i2cfast". (see also i2cfast)
2235
2236		CONFIG_I2C_MULTI_BUS
2237
2238		This option allows the use of multiple I2C buses, each of which
2239		must have a controller.	 At any point in time, only one bus is
2240		active.	 To switch to a different bus, use the 'i2c dev' command.
2241		Note that bus numbering is zero-based.
2242
2243		CONFIG_SYS_I2C_NOPROBES
2244
2245		This option specifies a list of I2C devices that will be skipped
2246		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2247		is set, specify a list of bus-device pairs.  Otherwise, specify
2248		a 1D array of device addresses
2249
2250		e.g.
2251			#undef	CONFIG_I2C_MULTI_BUS
2252			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2253
2254		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2255
2256			#define CONFIG_I2C_MULTI_BUS
2257			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2258
2259		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2260
2261		CONFIG_SYS_SPD_BUS_NUM
2262
2263		If defined, then this indicates the I2C bus number for DDR SPD.
2264		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2265
2266		CONFIG_SYS_RTC_BUS_NUM
2267
2268		If defined, then this indicates the I2C bus number for the RTC.
2269		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2270
2271		CONFIG_SYS_DTT_BUS_NUM
2272
2273		If defined, then this indicates the I2C bus number for the DTT.
2274		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2275
2276		CONFIG_SYS_I2C_DTT_ADDR:
2277
2278		If defined, specifies the I2C address of the DTT device.
2279		If not defined, then U-Boot uses predefined value for
2280		specified DTT device.
2281
2282		CONFIG_SOFT_I2C_READ_REPEATED_START
2283
2284		defining this will force the i2c_read() function in
2285		the soft_i2c driver to perform an I2C repeated start
2286		between writing the address pointer and reading the
2287		data.  If this define is omitted the default behaviour
2288		of doing a stop-start sequence will be used.  Most I2C
2289		devices can use either method, but some require one or
2290		the other.
2291
2292- SPI Support:	CONFIG_SPI
2293
2294		Enables SPI driver (so far only tested with
2295		SPI EEPROM, also an instance works with Crystal A/D and
2296		D/As on the SACSng board)
2297
2298		CONFIG_SH_SPI
2299
2300		Enables the driver for SPI controller on SuperH. Currently
2301		only SH7757 is supported.
2302
2303		CONFIG_SPI_X
2304
2305		Enables extended (16-bit) SPI EEPROM addressing.
2306		(symmetrical to CONFIG_I2C_X)
2307
2308		CONFIG_SOFT_SPI
2309
2310		Enables a software (bit-bang) SPI driver rather than
2311		using hardware support. This is a general purpose
2312		driver that only requires three general I/O port pins
2313		(two outputs, one input) to function. If this is
2314		defined, the board configuration must define several
2315		SPI configuration items (port pins to use, etc). For
2316		an example, see include/configs/sacsng.h.
2317
2318		CONFIG_HARD_SPI
2319
2320		Enables a hardware SPI driver for general-purpose reads
2321		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2322		must define a list of chip-select function pointers.
2323		Currently supported on some MPC8xxx processors.	 For an
2324		example, see include/configs/mpc8349emds.h.
2325
2326		CONFIG_MXC_SPI
2327
2328		Enables the driver for the SPI controllers on i.MX and MXC
2329		SoCs. Currently i.MX31/35/51 are supported.
2330
2331- FPGA Support: CONFIG_FPGA
2332
2333		Enables FPGA subsystem.
2334
2335		CONFIG_FPGA_<vendor>
2336
2337		Enables support for specific chip vendors.
2338		(ALTERA, XILINX)
2339
2340		CONFIG_FPGA_<family>
2341
2342		Enables support for FPGA family.
2343		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2344
2345		CONFIG_FPGA_COUNT
2346
2347		Specify the number of FPGA devices to support.
2348
2349		CONFIG_SYS_FPGA_PROG_FEEDBACK
2350
2351		Enable printing of hash marks during FPGA configuration.
2352
2353		CONFIG_SYS_FPGA_CHECK_BUSY
2354
2355		Enable checks on FPGA configuration interface busy
2356		status by the configuration function. This option
2357		will require a board or device specific function to
2358		be written.
2359
2360		CONFIG_FPGA_DELAY
2361
2362		If defined, a function that provides delays in the FPGA
2363		configuration driver.
2364
2365		CONFIG_SYS_FPGA_CHECK_CTRLC
2366		Allow Control-C to interrupt FPGA configuration
2367
2368		CONFIG_SYS_FPGA_CHECK_ERROR
2369
2370		Check for configuration errors during FPGA bitfile
2371		loading. For example, abort during Virtex II
2372		configuration if the INIT_B line goes low (which
2373		indicated a CRC error).
2374
2375		CONFIG_SYS_FPGA_WAIT_INIT
2376
2377		Maximum time to wait for the INIT_B line to deassert
2378		after PROB_B has been deasserted during a Virtex II
2379		FPGA configuration sequence. The default time is 500
2380		ms.
2381
2382		CONFIG_SYS_FPGA_WAIT_BUSY
2383
2384		Maximum time to wait for BUSY to deassert during
2385		Virtex II FPGA configuration. The default is 5 ms.
2386
2387		CONFIG_SYS_FPGA_WAIT_CONFIG
2388
2389		Time to wait after FPGA configuration. The default is
2390		200 ms.
2391
2392- Configuration Management:
2393		CONFIG_IDENT_STRING
2394
2395		If defined, this string will be added to the U-Boot
2396		version information (U_BOOT_VERSION)
2397
2398- Vendor Parameter Protection:
2399
2400		U-Boot considers the values of the environment
2401		variables "serial#" (Board Serial Number) and
2402		"ethaddr" (Ethernet Address) to be parameters that
2403		are set once by the board vendor / manufacturer, and
2404		protects these variables from casual modification by
2405		the user. Once set, these variables are read-only,
2406		and write or delete attempts are rejected. You can
2407		change this behaviour:
2408
2409		If CONFIG_ENV_OVERWRITE is #defined in your config
2410		file, the write protection for vendor parameters is
2411		completely disabled. Anybody can change or delete
2412		these parameters.
2413
2414		Alternatively, if you #define _both_ CONFIG_ETHADDR
2415		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2416		Ethernet address is installed in the environment,
2417		which can be changed exactly ONCE by the user. [The
2418		serial# is unaffected by this, i. e. it remains
2419		read-only.]
2420
2421		The same can be accomplished in a more flexible way
2422		for any variable by configuring the type of access
2423		to allow for those variables in the ".flags" variable
2424		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2425
2426- Protected RAM:
2427		CONFIG_PRAM
2428
2429		Define this variable to enable the reservation of
2430		"protected RAM", i. e. RAM which is not overwritten
2431		by U-Boot. Define CONFIG_PRAM to hold the number of
2432		kB you want to reserve for pRAM. You can overwrite
2433		this default value by defining an environment
2434		variable "pram" to the number of kB you want to
2435		reserve. Note that the board info structure will
2436		still show the full amount of RAM. If pRAM is
2437		reserved, a new environment variable "mem" will
2438		automatically be defined to hold the amount of
2439		remaining RAM in a form that can be passed as boot
2440		argument to Linux, for instance like that:
2441
2442			setenv bootargs ... mem=\${mem}
2443			saveenv
2444
2445		This way you can tell Linux not to use this memory,
2446		either, which results in a memory region that will
2447		not be affected by reboots.
2448
2449		*WARNING* If your board configuration uses automatic
2450		detection of the RAM size, you must make sure that
2451		this memory test is non-destructive. So far, the
2452		following board configurations are known to be
2453		"pRAM-clean":
2454
2455			IVMS8, IVML24, SPD8xx, TQM8xxL,
2456			HERMES, IP860, RPXlite, LWMON,
2457			FLAGADM, TQM8260
2458
2459- Access to physical memory region (> 4GB)
2460		Some basic support is provided for operations on memory not
2461		normally accessible to U-Boot - e.g. some architectures
2462		support access to more than 4GB of memory on 32-bit
2463		machines using physical address extension or similar.
2464		Define CONFIG_PHYSMEM to access this basic support, which
2465		currently only supports clearing the memory.
2466
2467- Error Recovery:
2468		CONFIG_PANIC_HANG
2469
2470		Define this variable to stop the system in case of a
2471		fatal error, so that you have to reset it manually.
2472		This is probably NOT a good idea for an embedded
2473		system where you want the system to reboot
2474		automatically as fast as possible, but it may be
2475		useful during development since you can try to debug
2476		the conditions that lead to the situation.
2477
2478		CONFIG_NET_RETRY_COUNT
2479
2480		This variable defines the number of retries for
2481		network operations like ARP, RARP, TFTP, or BOOTP
2482		before giving up the operation. If not defined, a
2483		default value of 5 is used.
2484
2485		CONFIG_ARP_TIMEOUT
2486
2487		Timeout waiting for an ARP reply in milliseconds.
2488
2489		CONFIG_NFS_TIMEOUT
2490
2491		Timeout in milliseconds used in NFS protocol.
2492		If you encounter "ERROR: Cannot umount" in nfs command,
2493		try longer timeout such as
2494		#define CONFIG_NFS_TIMEOUT 10000UL
2495
2496- Command Interpreter:
2497		CONFIG_AUTO_COMPLETE
2498
2499		Enable auto completion of commands using TAB.
2500
2501		Note that this feature has NOT been implemented yet
2502		for the "hush" shell.
2503
2504
2505		CONFIG_SYS_HUSH_PARSER
2506
2507		Define this variable to enable the "hush" shell (from
2508		Busybox) as command line interpreter, thus enabling
2509		powerful command line syntax like
2510		if...then...else...fi conditionals or `&&' and '||'
2511		constructs ("shell scripts").
2512
2513		If undefined, you get the old, much simpler behaviour
2514		with a somewhat smaller memory footprint.
2515
2516
2517		CONFIG_SYS_PROMPT_HUSH_PS2
2518
2519		This defines the secondary prompt string, which is
2520		printed when the command interpreter needs more input
2521		to complete a command. Usually "> ".
2522
2523	Note:
2524
2525		In the current implementation, the local variables
2526		space and global environment variables space are
2527		separated. Local variables are those you define by
2528		simply typing `name=value'. To access a local
2529		variable later on, you have write `$name' or
2530		`${name}'; to execute the contents of a variable
2531		directly type `$name' at the command prompt.
2532
2533		Global environment variables are those you use
2534		setenv/printenv to work with. To run a command stored
2535		in such a variable, you need to use the run command,
2536		and you must not use the '$' sign to access them.
2537
2538		To store commands and special characters in a
2539		variable, please use double quotation marks
2540		surrounding the whole text of the variable, instead
2541		of the backslashes before semicolons and special
2542		symbols.
2543
2544- Commandline Editing and History:
2545		CONFIG_CMDLINE_EDITING
2546
2547		Enable editing and History functions for interactive
2548		commandline input operations
2549
2550- Default Environment:
2551		CONFIG_EXTRA_ENV_SETTINGS
2552
2553		Define this to contain any number of null terminated
2554		strings (variable = value pairs) that will be part of
2555		the default environment compiled into the boot image.
2556
2557		For example, place something like this in your
2558		board's config file:
2559
2560		#define CONFIG_EXTRA_ENV_SETTINGS \
2561			"myvar1=value1\0" \
2562			"myvar2=value2\0"
2563
2564		Warning: This method is based on knowledge about the
2565		internal format how the environment is stored by the
2566		U-Boot code. This is NOT an official, exported
2567		interface! Although it is unlikely that this format
2568		will change soon, there is no guarantee either.
2569		You better know what you are doing here.
2570
2571		Note: overly (ab)use of the default environment is
2572		discouraged. Make sure to check other ways to preset
2573		the environment like the "source" command or the
2574		boot command first.
2575
2576		CONFIG_ENV_VARS_UBOOT_CONFIG
2577
2578		Define this in order to add variables describing the
2579		U-Boot build configuration to the default environment.
2580		These will be named arch, cpu, board, vendor, and soc.
2581
2582		Enabling this option will cause the following to be defined:
2583
2584		- CONFIG_SYS_ARCH
2585		- CONFIG_SYS_CPU
2586		- CONFIG_SYS_BOARD
2587		- CONFIG_SYS_VENDOR
2588		- CONFIG_SYS_SOC
2589
2590		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2591
2592		Define this in order to add variables describing certain
2593		run-time determined information about the hardware to the
2594		environment.  These will be named board_name, board_rev.
2595
2596		CONFIG_DELAY_ENVIRONMENT
2597
2598		Normally the environment is loaded when the board is
2599		intialised so that it is available to U-Boot. This inhibits
2600		that so that the environment is not available until
2601		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2602		this is instead controlled by the value of
2603		/config/load-environment.
2604
2605- DataFlash Support:
2606		CONFIG_HAS_DATAFLASH
2607
2608		Defining this option enables DataFlash features and
2609		allows to read/write in Dataflash via the standard
2610		commands cp, md...
2611
2612- Serial Flash support
2613		CONFIG_CMD_SF
2614
2615		Defining this option enables SPI flash commands
2616		'sf probe/read/write/erase/update'.
2617
2618		Usage requires an initial 'probe' to define the serial
2619		flash parameters, followed by read/write/erase/update
2620		commands.
2621
2622		The following defaults may be provided by the platform
2623		to handle the common case when only a single serial
2624		flash is present on the system.
2625
2626		CONFIG_SF_DEFAULT_BUS		Bus identifier
2627		CONFIG_SF_DEFAULT_CS		Chip-select
2628		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2629		CONFIG_SF_DEFAULT_SPEED		in Hz
2630
2631		CONFIG_CMD_SF_TEST
2632
2633		Define this option to include a destructive SPI flash
2634		test ('sf test').
2635
2636		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2637
2638		Define this option to use the Bank addr/Extended addr
2639		support on SPI flashes which has size > 16Mbytes.
2640
2641- SystemACE Support:
2642		CONFIG_SYSTEMACE
2643
2644		Adding this option adds support for Xilinx SystemACE
2645		chips attached via some sort of local bus. The address
2646		of the chip must also be defined in the
2647		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2648
2649		#define CONFIG_SYSTEMACE
2650		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2651
2652		When SystemACE support is added, the "ace" device type
2653		becomes available to the fat commands, i.e. fatls.
2654
2655- TFTP Fixed UDP Port:
2656		CONFIG_TFTP_PORT
2657
2658		If this is defined, the environment variable tftpsrcp
2659		is used to supply the TFTP UDP source port value.
2660		If tftpsrcp isn't defined, the normal pseudo-random port
2661		number generator is used.
2662
2663		Also, the environment variable tftpdstp is used to supply
2664		the TFTP UDP destination port value.  If tftpdstp isn't
2665		defined, the normal port 69 is used.
2666
2667		The purpose for tftpsrcp is to allow a TFTP server to
2668		blindly start the TFTP transfer using the pre-configured
2669		target IP address and UDP port. This has the effect of
2670		"punching through" the (Windows XP) firewall, allowing
2671		the remainder of the TFTP transfer to proceed normally.
2672		A better solution is to properly configure the firewall,
2673		but sometimes that is not allowed.
2674
2675- Hashing support:
2676		CONFIG_CMD_HASH
2677
2678		This enables a generic 'hash' command which can produce
2679		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2680
2681		CONFIG_HASH_VERIFY
2682
2683		Enable the hash verify command (hash -v). This adds to code
2684		size a little.
2685
2686		CONFIG_SHA1 - support SHA1 hashing
2687		CONFIG_SHA256 - support SHA256 hashing
2688
2689		Note: There is also a sha1sum command, which should perhaps
2690		be deprecated in favour of 'hash sha1'.
2691
2692- Freescale i.MX specific commands:
2693		CONFIG_CMD_HDMIDETECT
2694		This enables 'hdmidet' command which returns true if an
2695		HDMI monitor is detected.  This command is i.MX 6 specific.
2696
2697		CONFIG_CMD_BMODE
2698		This enables the 'bmode' (bootmode) command for forcing
2699		a boot from specific media.
2700
2701		This is useful for forcing the ROM's usb downloader to
2702		activate upon a watchdog reset which is nice when iterating
2703		on U-Boot.  Using the reset button or running bmode normal
2704		will set it back to normal.  This command currently
2705		supports i.MX53 and i.MX6.
2706
2707- Signing support:
2708		CONFIG_RSA
2709
2710		This enables the RSA algorithm used for FIT image verification
2711		in U-Boot. See doc/uImage/signature for more information.
2712
2713		The signing part is build into mkimage regardless of this
2714		option.
2715
2716
2717- Show boot progress:
2718		CONFIG_SHOW_BOOT_PROGRESS
2719
2720		Defining this option allows to add some board-
2721		specific code (calling a user-provided function
2722		"show_boot_progress(int)") that enables you to show
2723		the system's boot progress on some display (for
2724		example, some LED's) on your board. At the moment,
2725		the following checkpoints are implemented:
2726
2727- Detailed boot stage timing
2728		CONFIG_BOOTSTAGE
2729		Define this option to get detailed timing of each stage
2730		of the boot process.
2731
2732		CONFIG_BOOTSTAGE_USER_COUNT
2733		This is the number of available user bootstage records.
2734		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2735		a new ID will be allocated from this stash. If you exceed
2736		the limit, recording will stop.
2737
2738		CONFIG_BOOTSTAGE_REPORT
2739		Define this to print a report before boot, similar to this:
2740
2741		Timer summary in microseconds:
2742		       Mark    Elapsed  Stage
2743			  0          0  reset
2744		  3,575,678  3,575,678  board_init_f start
2745		  3,575,695         17  arch_cpu_init A9
2746		  3,575,777         82  arch_cpu_init done
2747		  3,659,598     83,821  board_init_r start
2748		  3,910,375    250,777  main_loop
2749		 29,916,167 26,005,792  bootm_start
2750		 30,361,327    445,160  start_kernel
2751
2752		CONFIG_CMD_BOOTSTAGE
2753		Add a 'bootstage' command which supports printing a report
2754		and un/stashing of bootstage data.
2755
2756		CONFIG_BOOTSTAGE_FDT
2757		Stash the bootstage information in the FDT. A root 'bootstage'
2758		node is created with each bootstage id as a child. Each child
2759		has a 'name' property and either 'mark' containing the
2760		mark time in microsecond, or 'accum' containing the
2761		accumulated time for that bootstage id in microseconds.
2762		For example:
2763
2764		bootstage {
2765			154 {
2766				name = "board_init_f";
2767				mark = <3575678>;
2768			};
2769			170 {
2770				name = "lcd";
2771				accum = <33482>;
2772			};
2773		};
2774
2775		Code in the Linux kernel can find this in /proc/devicetree.
2776
2777Legacy uImage format:
2778
2779  Arg	Where			When
2780    1	common/cmd_bootm.c	before attempting to boot an image
2781   -1	common/cmd_bootm.c	Image header has bad	 magic number
2782    2	common/cmd_bootm.c	Image header has correct magic number
2783   -2	common/cmd_bootm.c	Image header has bad	 checksum
2784    3	common/cmd_bootm.c	Image header has correct checksum
2785   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2786    4	common/cmd_bootm.c	Image data   has correct checksum
2787   -4	common/cmd_bootm.c	Image is for unsupported architecture
2788    5	common/cmd_bootm.c	Architecture check OK
2789   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2790    6	common/cmd_bootm.c	Image Type check OK
2791   -6	common/cmd_bootm.c	gunzip uncompression error
2792   -7	common/cmd_bootm.c	Unimplemented compression type
2793    7	common/cmd_bootm.c	Uncompression OK
2794    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2795   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2796
2797    9	common/image.c		Start initial ramdisk verification
2798  -10	common/image.c		Ramdisk header has bad	   magic number
2799  -11	common/image.c		Ramdisk header has bad	   checksum
2800   10	common/image.c		Ramdisk header is OK
2801  -12	common/image.c		Ramdisk data   has bad	   checksum
2802   11	common/image.c		Ramdisk data   has correct checksum
2803   12	common/image.c		Ramdisk verification complete, start loading
2804  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2805   13	common/image.c		Start multifile image verification
2806   14	common/image.c		No initial ramdisk, no multifile, continue.
2807
2808   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2809
2810  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2811  -31	post/post.c		POST test failed, detected by post_output_backlog()
2812  -32	post/post.c		POST test failed, detected by post_run_single()
2813
2814   34	common/cmd_doc.c	before loading a Image from a DOC device
2815  -35	common/cmd_doc.c	Bad usage of "doc" command
2816   35	common/cmd_doc.c	correct usage of "doc" command
2817  -36	common/cmd_doc.c	No boot device
2818   36	common/cmd_doc.c	correct boot device
2819  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2820   37	common/cmd_doc.c	correct chip ID found, device available
2821  -38	common/cmd_doc.c	Read Error on boot device
2822   38	common/cmd_doc.c	reading Image header from DOC device OK
2823  -39	common/cmd_doc.c	Image header has bad magic number
2824   39	common/cmd_doc.c	Image header has correct magic number
2825  -40	common/cmd_doc.c	Error reading Image from DOC device
2826   40	common/cmd_doc.c	Image header has correct magic number
2827   41	common/cmd_ide.c	before loading a Image from a IDE device
2828  -42	common/cmd_ide.c	Bad usage of "ide" command
2829   42	common/cmd_ide.c	correct usage of "ide" command
2830  -43	common/cmd_ide.c	No boot device
2831   43	common/cmd_ide.c	boot device found
2832  -44	common/cmd_ide.c	Device not available
2833   44	common/cmd_ide.c	Device available
2834  -45	common/cmd_ide.c	wrong partition selected
2835   45	common/cmd_ide.c	partition selected
2836  -46	common/cmd_ide.c	Unknown partition table
2837   46	common/cmd_ide.c	valid partition table found
2838  -47	common/cmd_ide.c	Invalid partition type
2839   47	common/cmd_ide.c	correct partition type
2840  -48	common/cmd_ide.c	Error reading Image Header on boot device
2841   48	common/cmd_ide.c	reading Image Header from IDE device OK
2842  -49	common/cmd_ide.c	Image header has bad magic number
2843   49	common/cmd_ide.c	Image header has correct magic number
2844  -50	common/cmd_ide.c	Image header has bad	 checksum
2845   50	common/cmd_ide.c	Image header has correct checksum
2846  -51	common/cmd_ide.c	Error reading Image from IDE device
2847   51	common/cmd_ide.c	reading Image from IDE device OK
2848   52	common/cmd_nand.c	before loading a Image from a NAND device
2849  -53	common/cmd_nand.c	Bad usage of "nand" command
2850   53	common/cmd_nand.c	correct usage of "nand" command
2851  -54	common/cmd_nand.c	No boot device
2852   54	common/cmd_nand.c	boot device found
2853  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2854   55	common/cmd_nand.c	correct chip ID found, device available
2855  -56	common/cmd_nand.c	Error reading Image Header on boot device
2856   56	common/cmd_nand.c	reading Image Header from NAND device OK
2857  -57	common/cmd_nand.c	Image header has bad magic number
2858   57	common/cmd_nand.c	Image header has correct magic number
2859  -58	common/cmd_nand.c	Error reading Image from NAND device
2860   58	common/cmd_nand.c	reading Image from NAND device OK
2861
2862  -60	common/env_common.c	Environment has a bad CRC, using default
2863
2864   64	net/eth.c		starting with Ethernet configuration.
2865  -64	net/eth.c		no Ethernet found.
2866   65	net/eth.c		Ethernet found.
2867
2868  -80	common/cmd_net.c	usage wrong
2869   80	common/cmd_net.c	before calling NetLoop()
2870  -81	common/cmd_net.c	some error in NetLoop() occurred
2871   81	common/cmd_net.c	NetLoop() back without error
2872  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2873   82	common/cmd_net.c	trying automatic boot
2874   83	common/cmd_net.c	running "source" command
2875  -83	common/cmd_net.c	some error in automatic boot or "source" command
2876   84	common/cmd_net.c	end without errors
2877
2878FIT uImage format:
2879
2880  Arg	Where			When
2881  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2882 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2883  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2884 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2885  102	common/cmd_bootm.c	Kernel unit name specified
2886 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2887  103	common/cmd_bootm.c	Found configuration node
2888  104	common/cmd_bootm.c	Got kernel subimage node offset
2889 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2890  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2891 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2892  106	common/cmd_bootm.c	Architecture check OK
2893 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2894  107	common/cmd_bootm.c	Kernel subimage type OK
2895 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2896  108	common/cmd_bootm.c	Got kernel subimage data/size
2897 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2898 -109	common/cmd_bootm.c	Can't get kernel subimage type
2899 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2900 -111	common/cmd_bootm.c	Can't get kernel subimage os
2901 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2902 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2903
2904  120	common/image.c		Start initial ramdisk verification
2905 -120	common/image.c		Ramdisk FIT image has incorrect format
2906  121	common/image.c		Ramdisk FIT image has correct format
2907  122	common/image.c		No ramdisk subimage unit name, using configuration
2908 -122	common/image.c		Can't get configuration for ramdisk subimage
2909  123	common/image.c		Ramdisk unit name specified
2910 -124	common/image.c		Can't get ramdisk subimage node offset
2911  125	common/image.c		Got ramdisk subimage node offset
2912 -125	common/image.c		Ramdisk subimage hash verification failed
2913  126	common/image.c		Ramdisk subimage hash verification OK
2914 -126	common/image.c		Ramdisk subimage for unsupported architecture
2915  127	common/image.c		Architecture check OK
2916 -127	common/image.c		Can't get ramdisk subimage data/size
2917  128	common/image.c		Got ramdisk subimage data/size
2918  129	common/image.c		Can't get ramdisk load address
2919 -129	common/image.c		Got ramdisk load address
2920
2921 -130	common/cmd_doc.c	Incorrect FIT image format
2922  131	common/cmd_doc.c	FIT image format OK
2923
2924 -140	common/cmd_ide.c	Incorrect FIT image format
2925  141	common/cmd_ide.c	FIT image format OK
2926
2927 -150	common/cmd_nand.c	Incorrect FIT image format
2928  151	common/cmd_nand.c	FIT image format OK
2929
2930- FIT image support:
2931		CONFIG_FIT
2932		Enable support for the FIT uImage format.
2933
2934		CONFIG_FIT_BEST_MATCH
2935		When no configuration is explicitly selected, default to the
2936		one whose fdt's compatibility field best matches that of
2937		U-Boot itself. A match is considered "best" if it matches the
2938		most specific compatibility entry of U-Boot's fdt's root node.
2939		The order of entries in the configuration's fdt is ignored.
2940
2941		CONFIG_FIT_SIGNATURE
2942		This option enables signature verification of FIT uImages,
2943		using a hash signed and verified using RSA. See
2944		doc/uImage.FIT/signature.txt for more details.
2945
2946- Standalone program support:
2947		CONFIG_STANDALONE_LOAD_ADDR
2948
2949		This option defines a board specific value for the
2950		address where standalone program gets loaded, thus
2951		overwriting the architecture dependent default
2952		settings.
2953
2954- Frame Buffer Address:
2955		CONFIG_FB_ADDR
2956
2957		Define CONFIG_FB_ADDR if you want to use specific
2958		address for frame buffer.  This is typically the case
2959		when using a graphics controller has separate video
2960		memory.  U-Boot will then place the frame buffer at
2961		the given address instead of dynamically reserving it
2962		in system RAM by calling lcd_setmem(), which grabs
2963		the memory for the frame buffer depending on the
2964		configured panel size.
2965
2966		Please see board_init_f function.
2967
2968- Automatic software updates via TFTP server
2969		CONFIG_UPDATE_TFTP
2970		CONFIG_UPDATE_TFTP_CNT_MAX
2971		CONFIG_UPDATE_TFTP_MSEC_MAX
2972
2973		These options enable and control the auto-update feature;
2974		for a more detailed description refer to doc/README.update.
2975
2976- MTD Support (mtdparts command, UBI support)
2977		CONFIG_MTD_DEVICE
2978
2979		Adds the MTD device infrastructure from the Linux kernel.
2980		Needed for mtdparts command support.
2981
2982		CONFIG_MTD_PARTITIONS
2983
2984		Adds the MTD partitioning infrastructure from the Linux
2985		kernel. Needed for UBI support.
2986
2987- UBI support
2988		CONFIG_CMD_UBI
2989
2990		Adds commands for interacting with MTD partitions formatted
2991		with the UBI flash translation layer
2992
2993		Requires also defining CONFIG_RBTREE
2994
2995		CONFIG_UBI_SILENCE_MSG
2996
2997		Make the verbose messages from UBI stop printing.  This leaves
2998		warnings and errors enabled.
2999
3000- UBIFS support
3001		CONFIG_CMD_UBIFS
3002
3003		Adds commands for interacting with UBI volumes formatted as
3004		UBIFS.  UBIFS is read-only in u-boot.
3005
3006		Requires UBI support as well as CONFIG_LZO
3007
3008		CONFIG_UBIFS_SILENCE_MSG
3009
3010		Make the verbose messages from UBIFS stop printing.  This leaves
3011		warnings and errors enabled.
3012
3013- SPL framework
3014		CONFIG_SPL
3015		Enable building of SPL globally.
3016
3017		CONFIG_SPL_LDSCRIPT
3018		LDSCRIPT for linking the SPL binary.
3019
3020		CONFIG_SPL_MAX_FOOTPRINT
3021		Maximum size in memory allocated to the SPL, BSS included.
3022		When defined, the linker checks that the actual memory
3023		used by SPL from _start to __bss_end does not exceed it.
3024		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3025		must not be both defined at the same time.
3026
3027		CONFIG_SPL_MAX_SIZE
3028		Maximum size of the SPL image (text, data, rodata, and
3029		linker lists sections), BSS excluded.
3030		When defined, the linker checks that the actual size does
3031		not exceed it.
3032
3033		CONFIG_SPL_TEXT_BASE
3034		TEXT_BASE for linking the SPL binary.
3035
3036		CONFIG_SPL_RELOC_TEXT_BASE
3037		Address to relocate to.  If unspecified, this is equal to
3038		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3039
3040		CONFIG_SPL_BSS_START_ADDR
3041		Link address for the BSS within the SPL binary.
3042
3043		CONFIG_SPL_BSS_MAX_SIZE
3044		Maximum size in memory allocated to the SPL BSS.
3045		When defined, the linker checks that the actual memory used
3046		by SPL from __bss_start to __bss_end does not exceed it.
3047		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3048		must not be both defined at the same time.
3049
3050		CONFIG_SPL_STACK
3051		Adress of the start of the stack SPL will use
3052
3053		CONFIG_SPL_RELOC_STACK
3054		Adress of the start of the stack SPL will use after
3055		relocation.  If unspecified, this is equal to
3056		CONFIG_SPL_STACK.
3057
3058		CONFIG_SYS_SPL_MALLOC_START
3059		Starting address of the malloc pool used in SPL.
3060
3061		CONFIG_SYS_SPL_MALLOC_SIZE
3062		The size of the malloc pool used in SPL.
3063
3064		CONFIG_SPL_FRAMEWORK
3065		Enable the SPL framework under common/.  This framework
3066		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3067		NAND loading of the Linux Kernel.
3068
3069		CONFIG_SPL_DISPLAY_PRINT
3070		For ARM, enable an optional function to print more information
3071		about the running system.
3072
3073		CONFIG_SPL_INIT_MINIMAL
3074		Arch init code should be built for a very small image
3075
3076		CONFIG_SPL_LIBCOMMON_SUPPORT
3077		Support for common/libcommon.o in SPL binary
3078
3079		CONFIG_SPL_LIBDISK_SUPPORT
3080		Support for disk/libdisk.o in SPL binary
3081
3082		CONFIG_SPL_I2C_SUPPORT
3083		Support for drivers/i2c/libi2c.o in SPL binary
3084
3085		CONFIG_SPL_GPIO_SUPPORT
3086		Support for drivers/gpio/libgpio.o in SPL binary
3087
3088		CONFIG_SPL_MMC_SUPPORT
3089		Support for drivers/mmc/libmmc.o in SPL binary
3090
3091		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3092		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3093		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3094		Address, size and partition on the MMC to load U-Boot from
3095		when the MMC is being used in raw mode.
3096
3097		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3098		Sector to load kernel uImage from when MMC is being
3099		used in raw mode (for Falcon mode)
3100
3101		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3102		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3103		Sector and number of sectors to load kernel argument
3104		parameters from when MMC is being used in raw mode
3105		(for falcon mode)
3106
3107		CONFIG_SPL_FAT_SUPPORT
3108		Support for fs/fat/libfat.o in SPL binary
3109
3110		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3111		Filename to read to load U-Boot when reading from FAT
3112
3113		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3114		Filename to read to load kernel uImage when reading
3115		from FAT (for Falcon mode)
3116
3117		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3118		Filename to read to load kernel argument parameters
3119		when reading from FAT (for Falcon mode)
3120
3121		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3122		Set this for NAND SPL on PPC mpc83xx targets, so that
3123		start.S waits for the rest of the SPL to load before
3124		continuing (the hardware starts execution after just
3125		loading the first page rather than the full 4K).
3126
3127		CONFIG_SPL_NAND_BASE
3128		Include nand_base.c in the SPL.  Requires
3129		CONFIG_SPL_NAND_DRIVERS.
3130
3131		CONFIG_SPL_NAND_DRIVERS
3132		SPL uses normal NAND drivers, not minimal drivers.
3133
3134		CONFIG_SPL_NAND_ECC
3135		Include standard software ECC in the SPL
3136
3137		CONFIG_SPL_NAND_SIMPLE
3138		Support for NAND boot using simple NAND drivers that
3139		expose the cmd_ctrl() interface.
3140
3141		CONFIG_SPL_MPC8XXX_INIT_DDR_SUPPORT
3142		Set for the SPL on PPC mpc8xxx targets, support for
3143		arch/powerpc/cpu/mpc8xxx/ddr/libddr.o in SPL binary.
3144
3145		CONFIG_SPL_COMMON_INIT_DDR
3146		Set for common ddr init with serial presence detect in
3147		SPL binary.
3148
3149		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3150		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3151		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3152		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3153		CONFIG_SYS_NAND_ECCBYTES
3154		Defines the size and behavior of the NAND that SPL uses
3155		to read U-Boot
3156
3157		CONFIG_SYS_NAND_U_BOOT_OFFS
3158		Location in NAND to read U-Boot from
3159
3160		CONFIG_SYS_NAND_U_BOOT_DST
3161		Location in memory to load U-Boot to
3162
3163		CONFIG_SYS_NAND_U_BOOT_SIZE
3164		Size of image to load
3165
3166		CONFIG_SYS_NAND_U_BOOT_START
3167		Entry point in loaded image to jump to
3168
3169		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3170		Define this if you need to first read the OOB and then the
3171		data. This is used for example on davinci plattforms.
3172
3173		CONFIG_SPL_OMAP3_ID_NAND
3174		Support for an OMAP3-specific set of functions to return the
3175		ID and MFR of the first attached NAND chip, if present.
3176
3177		CONFIG_SPL_SERIAL_SUPPORT
3178		Support for drivers/serial/libserial.o in SPL binary
3179
3180		CONFIG_SPL_SPI_FLASH_SUPPORT
3181		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3182
3183		CONFIG_SPL_SPI_SUPPORT
3184		Support for drivers/spi/libspi.o in SPL binary
3185
3186		CONFIG_SPL_RAM_DEVICE
3187		Support for running image already present in ram, in SPL binary
3188
3189		CONFIG_SPL_LIBGENERIC_SUPPORT
3190		Support for lib/libgeneric.o in SPL binary
3191
3192		CONFIG_SPL_ENV_SUPPORT
3193		Support for the environment operating in SPL binary
3194
3195		CONFIG_SPL_NET_SUPPORT
3196		Support for the net/libnet.o in SPL binary.
3197		It conflicts with SPL env from storage medium specified by
3198		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3199
3200		CONFIG_SPL_PAD_TO
3201		Image offset to which the SPL should be padded before appending
3202		the SPL payload. By default, this is defined as
3203		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3204		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3205		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3206
3207		CONFIG_SPL_TARGET
3208		Final target image containing SPL and payload.  Some SPLs
3209		use an arch-specific makefile fragment instead, for
3210		example if more than one image needs to be produced.
3211
3212		CONFIG_FIT_SPL_PRINT
3213		Printing information about a FIT image adds quite a bit of
3214		code to SPL. So this is normally disabled in SPL. Use this
3215		option to re-enable it. This will affect the output of the
3216		bootm command when booting a FIT image.
3217
3218- TPL framework
3219		CONFIG_TPL
3220		Enable building of TPL globally.
3221
3222		CONFIG_TPL_PAD_TO
3223		Image offset to which the TPL should be padded before appending
3224		the TPL payload. By default, this is defined as
3225		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3226		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3227		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3228
3229Modem Support:
3230--------------
3231
3232[so far only for SMDK2400 boards]
3233
3234- Modem support enable:
3235		CONFIG_MODEM_SUPPORT
3236
3237- RTS/CTS Flow control enable:
3238		CONFIG_HWFLOW
3239
3240- Modem debug support:
3241		CONFIG_MODEM_SUPPORT_DEBUG
3242
3243		Enables debugging stuff (char screen[1024], dbg())
3244		for modem support. Useful only with BDI2000.
3245
3246- Interrupt support (PPC):
3247
3248		There are common interrupt_init() and timer_interrupt()
3249		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3250		for CPU specific initialization. interrupt_init_cpu()
3251		should set decrementer_count to appropriate value. If
3252		CPU resets decrementer automatically after interrupt
3253		(ppc4xx) it should set decrementer_count to zero.
3254		timer_interrupt() calls timer_interrupt_cpu() for CPU
3255		specific handling. If board has watchdog / status_led
3256		/ other_activity_monitor it works automatically from
3257		general timer_interrupt().
3258
3259- General:
3260
3261		In the target system modem support is enabled when a
3262		specific key (key combination) is pressed during
3263		power-on. Otherwise U-Boot will boot normally
3264		(autoboot). The key_pressed() function is called from
3265		board_init(). Currently key_pressed() is a dummy
3266		function, returning 1 and thus enabling modem
3267		initialization.
3268
3269		If there are no modem init strings in the
3270		environment, U-Boot proceed to autoboot; the
3271		previous output (banner, info printfs) will be
3272		suppressed, though.
3273
3274		See also: doc/README.Modem
3275
3276Board initialization settings:
3277------------------------------
3278
3279During Initialization u-boot calls a number of board specific functions
3280to allow the preparation of board specific prerequisites, e.g. pin setup
3281before drivers are initialized. To enable these callbacks the
3282following configuration macros have to be defined. Currently this is
3283architecture specific, so please check arch/your_architecture/lib/board.c
3284typically in board_init_f() and board_init_r().
3285
3286- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3287- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3288- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3289- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3290
3291Configuration Settings:
3292-----------------------
3293
3294- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3295		undefine this when you're short of memory.
3296
3297- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3298		width of the commands listed in the 'help' command output.
3299
3300- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3301		prompt for user input.
3302
3303- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3304
3305- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3306
3307- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3308
3309- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3310		the application (usually a Linux kernel) when it is
3311		booted
3312
3313- CONFIG_SYS_BAUDRATE_TABLE:
3314		List of legal baudrate settings for this board.
3315
3316- CONFIG_SYS_CONSOLE_INFO_QUIET
3317		Suppress display of console information at boot.
3318
3319- CONFIG_SYS_CONSOLE_IS_IN_ENV
3320		If the board specific function
3321			extern int overwrite_console (void);
3322		returns 1, the stdin, stderr and stdout are switched to the
3323		serial port, else the settings in the environment are used.
3324
3325- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3326		Enable the call to overwrite_console().
3327
3328- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3329		Enable overwrite of previous console environment settings.
3330
3331- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3332		Begin and End addresses of the area used by the
3333		simple memory test.
3334
3335- CONFIG_SYS_ALT_MEMTEST:
3336		Enable an alternate, more extensive memory test.
3337
3338- CONFIG_SYS_MEMTEST_SCRATCH:
3339		Scratch address used by the alternate memory test
3340		You only need to set this if address zero isn't writeable
3341
3342- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3343		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3344		this specified memory area will get subtracted from the top
3345		(end) of RAM and won't get "touched" at all by U-Boot. By
3346		fixing up gd->ram_size the Linux kernel should gets passed
3347		the now "corrected" memory size and won't touch it either.
3348		This should work for arch/ppc and arch/powerpc. Only Linux
3349		board ports in arch/powerpc with bootwrapper support that
3350		recalculate the memory size from the SDRAM controller setup
3351		will have to get fixed in Linux additionally.
3352
3353		This option can be used as a workaround for the 440EPx/GRx
3354		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3355		be touched.
3356
3357		WARNING: Please make sure that this value is a multiple of
3358		the Linux page size (normally 4k). If this is not the case,
3359		then the end address of the Linux memory will be located at a
3360		non page size aligned address and this could cause major
3361		problems.
3362
3363- CONFIG_SYS_LOADS_BAUD_CHANGE:
3364		Enable temporary baudrate change while serial download
3365
3366- CONFIG_SYS_SDRAM_BASE:
3367		Physical start address of SDRAM. _Must_ be 0 here.
3368
3369- CONFIG_SYS_MBIO_BASE:
3370		Physical start address of Motherboard I/O (if using a
3371		Cogent motherboard)
3372
3373- CONFIG_SYS_FLASH_BASE:
3374		Physical start address of Flash memory.
3375
3376- CONFIG_SYS_MONITOR_BASE:
3377		Physical start address of boot monitor code (set by
3378		make config files to be same as the text base address
3379		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3380		CONFIG_SYS_FLASH_BASE when booting from flash.
3381
3382- CONFIG_SYS_MONITOR_LEN:
3383		Size of memory reserved for monitor code, used to
3384		determine _at_compile_time_ (!) if the environment is
3385		embedded within the U-Boot image, or in a separate
3386		flash sector.
3387
3388- CONFIG_SYS_MALLOC_LEN:
3389		Size of DRAM reserved for malloc() use.
3390
3391- CONFIG_SYS_BOOTM_LEN:
3392		Normally compressed uImages are limited to an
3393		uncompressed size of 8 MBytes. If this is not enough,
3394		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3395		to adjust this setting to your needs.
3396
3397- CONFIG_SYS_BOOTMAPSZ:
3398		Maximum size of memory mapped by the startup code of
3399		the Linux kernel; all data that must be processed by
3400		the Linux kernel (bd_info, boot arguments, FDT blob if
3401		used) must be put below this limit, unless "bootm_low"
3402		environment variable is defined and non-zero. In such case
3403		all data for the Linux kernel must be between "bootm_low"
3404		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3405		variable "bootm_mapsize" will override the value of
3406		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3407		then the value in "bootm_size" will be used instead.
3408
3409- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3410		Enable initrd_high functionality.  If defined then the
3411		initrd_high feature is enabled and the bootm ramdisk subcommand
3412		is enabled.
3413
3414- CONFIG_SYS_BOOT_GET_CMDLINE:
3415		Enables allocating and saving kernel cmdline in space between
3416		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3417
3418- CONFIG_SYS_BOOT_GET_KBD:
3419		Enables allocating and saving a kernel copy of the bd_info in
3420		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3421
3422- CONFIG_SYS_MAX_FLASH_BANKS:
3423		Max number of Flash memory banks
3424
3425- CONFIG_SYS_MAX_FLASH_SECT:
3426		Max number of sectors on a Flash chip
3427
3428- CONFIG_SYS_FLASH_ERASE_TOUT:
3429		Timeout for Flash erase operations (in ms)
3430
3431- CONFIG_SYS_FLASH_WRITE_TOUT:
3432		Timeout for Flash write operations (in ms)
3433
3434- CONFIG_SYS_FLASH_LOCK_TOUT
3435		Timeout for Flash set sector lock bit operation (in ms)
3436
3437- CONFIG_SYS_FLASH_UNLOCK_TOUT
3438		Timeout for Flash clear lock bits operation (in ms)
3439
3440- CONFIG_SYS_FLASH_PROTECTION
3441		If defined, hardware flash sectors protection is used
3442		instead of U-Boot software protection.
3443
3444- CONFIG_SYS_DIRECT_FLASH_TFTP:
3445
3446		Enable TFTP transfers directly to flash memory;
3447		without this option such a download has to be
3448		performed in two steps: (1) download to RAM, and (2)
3449		copy from RAM to flash.
3450
3451		The two-step approach is usually more reliable, since
3452		you can check if the download worked before you erase
3453		the flash, but in some situations (when system RAM is
3454		too limited to allow for a temporary copy of the
3455		downloaded image) this option may be very useful.
3456
3457- CONFIG_SYS_FLASH_CFI:
3458		Define if the flash driver uses extra elements in the
3459		common flash structure for storing flash geometry.
3460
3461- CONFIG_FLASH_CFI_DRIVER
3462		This option also enables the building of the cfi_flash driver
3463		in the drivers directory
3464
3465- CONFIG_FLASH_CFI_MTD
3466		This option enables the building of the cfi_mtd driver
3467		in the drivers directory. The driver exports CFI flash
3468		to the MTD layer.
3469
3470- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3471		Use buffered writes to flash.
3472
3473- CONFIG_FLASH_SPANSION_S29WS_N
3474		s29ws-n MirrorBit flash has non-standard addresses for buffered
3475		write commands.
3476
3477- CONFIG_SYS_FLASH_QUIET_TEST
3478		If this option is defined, the common CFI flash doesn't
3479		print it's warning upon not recognized FLASH banks. This
3480		is useful, if some of the configured banks are only
3481		optionally available.
3482
3483- CONFIG_FLASH_SHOW_PROGRESS
3484		If defined (must be an integer), print out countdown
3485		digits and dots.  Recommended value: 45 (9..1) for 80
3486		column displays, 15 (3..1) for 40 column displays.
3487
3488- CONFIG_FLASH_VERIFY
3489		If defined, the content of the flash (destination) is compared
3490		against the source after the write operation. An error message
3491		will be printed when the contents are not identical.
3492		Please note that this option is useless in nearly all cases,
3493		since such flash programming errors usually are detected earlier
3494		while unprotecting/erasing/programming. Please only enable
3495		this option if you really know what you are doing.
3496
3497- CONFIG_SYS_RX_ETH_BUFFER:
3498		Defines the number of Ethernet receive buffers. On some
3499		Ethernet controllers it is recommended to set this value
3500		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3501		buffers can be full shortly after enabling the interface
3502		on high Ethernet traffic.
3503		Defaults to 4 if not defined.
3504
3505- CONFIG_ENV_MAX_ENTRIES
3506
3507	Maximum number of entries in the hash table that is used
3508	internally to store the environment settings. The default
3509	setting is supposed to be generous and should work in most
3510	cases. This setting can be used to tune behaviour; see
3511	lib/hashtable.c for details.
3512
3513- CONFIG_ENV_FLAGS_LIST_DEFAULT
3514- CONFIG_ENV_FLAGS_LIST_STATIC
3515	Enable validation of the values given to environment variables when
3516	calling env set.  Variables can be restricted to only decimal,
3517	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3518	the variables can also be restricted to IP address or MAC address.
3519
3520	The format of the list is:
3521		type_attribute = [s|d|x|b|i|m]
3522		access_atribute = [a|r|o|c]
3523		attributes = type_attribute[access_atribute]
3524		entry = variable_name[:attributes]
3525		list = entry[,list]
3526
3527	The type attributes are:
3528		s - String (default)
3529		d - Decimal
3530		x - Hexadecimal
3531		b - Boolean ([1yYtT|0nNfF])
3532		i - IP address
3533		m - MAC address
3534
3535	The access attributes are:
3536		a - Any (default)
3537		r - Read-only
3538		o - Write-once
3539		c - Change-default
3540
3541	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3542		Define this to a list (string) to define the ".flags"
3543		envirnoment variable in the default or embedded environment.
3544
3545	- CONFIG_ENV_FLAGS_LIST_STATIC
3546		Define this to a list (string) to define validation that
3547		should be done if an entry is not found in the ".flags"
3548		environment variable.  To override a setting in the static
3549		list, simply add an entry for the same variable name to the
3550		".flags" variable.
3551
3552- CONFIG_ENV_ACCESS_IGNORE_FORCE
3553	If defined, don't allow the -f switch to env set override variable
3554	access flags.
3555
3556- CONFIG_SYS_GENERIC_BOARD
3557	This selects the architecture-generic board system instead of the
3558	architecture-specific board files. It is intended to move boards
3559	to this new framework over time. Defining this will disable the
3560	arch/foo/lib/board.c file and use common/board_f.c and
3561	common/board_r.c instead. To use this option your architecture
3562	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3563	its config.mk file). If you find problems enabling this option on
3564	your board please report the problem and send patches!
3565
3566- CONFIG_SYS_SYM_OFFSETS
3567	This is set by architectures that use offsets for link symbols
3568	instead of absolute values. So bss_start is obtained using an
3569	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3570	directly. You should not need to touch this setting.
3571
3572- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3573	This is set by OMAP boards for the max time that reset should
3574	be asserted. See doc/README.omap-reset-time for details on how
3575	the value can be calulated on a given board.
3576
3577The following definitions that deal with the placement and management
3578of environment data (variable area); in general, we support the
3579following configurations:
3580
3581- CONFIG_BUILD_ENVCRC:
3582
3583	Builds up envcrc with the target environment so that external utils
3584	may easily extract it and embed it in final U-Boot images.
3585
3586- CONFIG_ENV_IS_IN_FLASH:
3587
3588	Define this if the environment is in flash memory.
3589
3590	a) The environment occupies one whole flash sector, which is
3591	   "embedded" in the text segment with the U-Boot code. This
3592	   happens usually with "bottom boot sector" or "top boot
3593	   sector" type flash chips, which have several smaller
3594	   sectors at the start or the end. For instance, such a
3595	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3596	   such a case you would place the environment in one of the
3597	   4 kB sectors - with U-Boot code before and after it. With
3598	   "top boot sector" type flash chips, you would put the
3599	   environment in one of the last sectors, leaving a gap
3600	   between U-Boot and the environment.
3601
3602	- CONFIG_ENV_OFFSET:
3603
3604	   Offset of environment data (variable area) to the
3605	   beginning of flash memory; for instance, with bottom boot
3606	   type flash chips the second sector can be used: the offset
3607	   for this sector is given here.
3608
3609	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3610
3611	- CONFIG_ENV_ADDR:
3612
3613	   This is just another way to specify the start address of
3614	   the flash sector containing the environment (instead of
3615	   CONFIG_ENV_OFFSET).
3616
3617	- CONFIG_ENV_SECT_SIZE:
3618
3619	   Size of the sector containing the environment.
3620
3621
3622	b) Sometimes flash chips have few, equal sized, BIG sectors.
3623	   In such a case you don't want to spend a whole sector for
3624	   the environment.
3625
3626	- CONFIG_ENV_SIZE:
3627
3628	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3629	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3630	   of this flash sector for the environment. This saves
3631	   memory for the RAM copy of the environment.
3632
3633	   It may also save flash memory if you decide to use this
3634	   when your environment is "embedded" within U-Boot code,
3635	   since then the remainder of the flash sector could be used
3636	   for U-Boot code. It should be pointed out that this is
3637	   STRONGLY DISCOURAGED from a robustness point of view:
3638	   updating the environment in flash makes it always
3639	   necessary to erase the WHOLE sector. If something goes
3640	   wrong before the contents has been restored from a copy in
3641	   RAM, your target system will be dead.
3642
3643	- CONFIG_ENV_ADDR_REDUND
3644	  CONFIG_ENV_SIZE_REDUND
3645
3646	   These settings describe a second storage area used to hold
3647	   a redundant copy of the environment data, so that there is
3648	   a valid backup copy in case there is a power failure during
3649	   a "saveenv" operation.
3650
3651BE CAREFUL! Any changes to the flash layout, and some changes to the
3652source code will make it necessary to adapt <board>/u-boot.lds*
3653accordingly!
3654
3655
3656- CONFIG_ENV_IS_IN_NVRAM:
3657
3658	Define this if you have some non-volatile memory device
3659	(NVRAM, battery buffered SRAM) which you want to use for the
3660	environment.
3661
3662	- CONFIG_ENV_ADDR:
3663	- CONFIG_ENV_SIZE:
3664
3665	  These two #defines are used to determine the memory area you
3666	  want to use for environment. It is assumed that this memory
3667	  can just be read and written to, without any special
3668	  provision.
3669
3670BE CAREFUL! The first access to the environment happens quite early
3671in U-Boot initalization (when we try to get the setting of for the
3672console baudrate). You *MUST* have mapped your NVRAM area then, or
3673U-Boot will hang.
3674
3675Please note that even with NVRAM we still use a copy of the
3676environment in RAM: we could work on NVRAM directly, but we want to
3677keep settings there always unmodified except somebody uses "saveenv"
3678to save the current settings.
3679
3680
3681- CONFIG_ENV_IS_IN_EEPROM:
3682
3683	Use this if you have an EEPROM or similar serial access
3684	device and a driver for it.
3685
3686	- CONFIG_ENV_OFFSET:
3687	- CONFIG_ENV_SIZE:
3688
3689	  These two #defines specify the offset and size of the
3690	  environment area within the total memory of your EEPROM.
3691
3692	- CONFIG_SYS_I2C_EEPROM_ADDR:
3693	  If defined, specified the chip address of the EEPROM device.
3694	  The default address is zero.
3695
3696	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3697	  If defined, the number of bits used to address bytes in a
3698	  single page in the EEPROM device.  A 64 byte page, for example
3699	  would require six bits.
3700
3701	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3702	  If defined, the number of milliseconds to delay between
3703	  page writes.	The default is zero milliseconds.
3704
3705	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3706	  The length in bytes of the EEPROM memory array address.  Note
3707	  that this is NOT the chip address length!
3708
3709	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3710	  EEPROM chips that implement "address overflow" are ones
3711	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3712	  address and the extra bits end up in the "chip address" bit
3713	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3714	  byte chips.
3715
3716	  Note that we consider the length of the address field to
3717	  still be one byte because the extra address bits are hidden
3718	  in the chip address.
3719
3720	- CONFIG_SYS_EEPROM_SIZE:
3721	  The size in bytes of the EEPROM device.
3722
3723	- CONFIG_ENV_EEPROM_IS_ON_I2C
3724	  define this, if you have I2C and SPI activated, and your
3725	  EEPROM, which holds the environment, is on the I2C bus.
3726
3727	- CONFIG_I2C_ENV_EEPROM_BUS
3728	  if you have an Environment on an EEPROM reached over
3729	  I2C muxes, you can define here, how to reach this
3730	  EEPROM. For example:
3731
3732	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1
3733
3734	  EEPROM which holds the environment, is reached over
3735	  a pca9547 i2c mux with address 0x70, channel 3.
3736
3737- CONFIG_ENV_IS_IN_DATAFLASH:
3738
3739	Define this if you have a DataFlash memory device which you
3740	want to use for the environment.
3741
3742	- CONFIG_ENV_OFFSET:
3743	- CONFIG_ENV_ADDR:
3744	- CONFIG_ENV_SIZE:
3745
3746	  These three #defines specify the offset and size of the
3747	  environment area within the total memory of your DataFlash placed
3748	  at the specified address.
3749
3750- CONFIG_ENV_IS_IN_REMOTE:
3751
3752	Define this if you have a remote memory space which you
3753	want to use for the local device's environment.
3754
3755	- CONFIG_ENV_ADDR:
3756	- CONFIG_ENV_SIZE:
3757
3758	  These two #defines specify the address and size of the
3759	  environment area within the remote memory space. The
3760	  local device can get the environment from remote memory
3761	  space by SRIO or PCIE links.
3762
3763BE CAREFUL! For some special cases, the local device can not use
3764"saveenv" command. For example, the local device will get the
3765environment stored in a remote NOR flash by SRIO or PCIE link,
3766but it can not erase, write this NOR flash by SRIO or PCIE interface.
3767
3768- CONFIG_ENV_IS_IN_NAND:
3769
3770	Define this if you have a NAND device which you want to use
3771	for the environment.
3772
3773	- CONFIG_ENV_OFFSET:
3774	- CONFIG_ENV_SIZE:
3775
3776	  These two #defines specify the offset and size of the environment
3777	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3778	  aligned to an erase block boundary.
3779
3780	- CONFIG_ENV_OFFSET_REDUND (optional):
3781
3782	  This setting describes a second storage area of CONFIG_ENV_SIZE
3783	  size used to hold a redundant copy of the environment data, so
3784	  that there is a valid backup copy in case there is a power failure
3785	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3786	  aligned to an erase block boundary.
3787
3788	- CONFIG_ENV_RANGE (optional):
3789
3790	  Specifies the length of the region in which the environment
3791	  can be written.  This should be a multiple of the NAND device's
3792	  block size.  Specifying a range with more erase blocks than
3793	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3794	  the range to be avoided.
3795
3796	- CONFIG_ENV_OFFSET_OOB (optional):
3797
3798	  Enables support for dynamically retrieving the offset of the
3799	  environment from block zero's out-of-band data.  The
3800	  "nand env.oob" command can be used to record this offset.
3801	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3802	  using CONFIG_ENV_OFFSET_OOB.
3803
3804- CONFIG_NAND_ENV_DST
3805
3806	Defines address in RAM to which the nand_spl code should copy the
3807	environment. If redundant environment is used, it will be copied to
3808	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3809
3810- CONFIG_ENV_IS_IN_UBI:
3811
3812	Define this if you have an UBI volume that you want to use for the
3813	environment.  This has the benefit of wear-leveling the environment
3814	accesses, which is important on NAND.
3815
3816	- CONFIG_ENV_UBI_PART:
3817
3818	  Define this to a string that is the mtd partition containing the UBI.
3819
3820	- CONFIG_ENV_UBI_VOLUME:
3821
3822	  Define this to the name of the volume that you want to store the
3823	  environment in.
3824
3825	- CONFIG_ENV_UBI_VOLUME_REDUND:
3826
3827	  Define this to the name of another volume to store a second copy of
3828	  the environment in.  This will enable redundant environments in UBI.
3829	  It is assumed that both volumes are in the same MTD partition.
3830
3831	- CONFIG_UBI_SILENCE_MSG
3832	- CONFIG_UBIFS_SILENCE_MSG
3833
3834	  You will probably want to define these to avoid a really noisy system
3835	  when storing the env in UBI.
3836
3837- CONFIG_ENV_IS_IN_MMC:
3838
3839	Define this if you have an MMC device which you want to use for the
3840	environment.
3841
3842	- CONFIG_SYS_MMC_ENV_DEV:
3843
3844	  Specifies which MMC device the environment is stored in.
3845
3846	- CONFIG_SYS_MMC_ENV_PART (optional):
3847
3848	  Specifies which MMC partition the environment is stored in. If not
3849	  set, defaults to partition 0, the user area. Common values might be
3850	  1 (first MMC boot partition), 2 (second MMC boot partition).
3851
3852	- CONFIG_ENV_OFFSET:
3853	- CONFIG_ENV_SIZE:
3854
3855	  These two #defines specify the offset and size of the environment
3856	  area within the specified MMC device.
3857
3858	  If offset is positive (the usual case), it is treated as relative to
3859	  the start of the MMC partition. If offset is negative, it is treated
3860	  as relative to the end of the MMC partition. This can be useful if
3861	  your board may be fitted with different MMC devices, which have
3862	  different sizes for the MMC partitions, and you always want the
3863	  environment placed at the very end of the partition, to leave the
3864	  maximum possible space before it, to store other data.
3865
3866	  These two values are in units of bytes, but must be aligned to an
3867	  MMC sector boundary.
3868
3869	- CONFIG_ENV_OFFSET_REDUND (optional):
3870
3871	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3872	  hold a redundant copy of the environment data. This provides a
3873	  valid backup copy in case the other copy is corrupted, e.g. due
3874	  to a power failure during a "saveenv" operation.
3875
3876	  This value may also be positive or negative; this is handled in the
3877	  same way as CONFIG_ENV_OFFSET.
3878
3879	  This value is also in units of bytes, but must also be aligned to
3880	  an MMC sector boundary.
3881
3882	- CONFIG_ENV_SIZE_REDUND (optional):
3883
3884	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
3885	  set. If this value is set, it must be set to the same value as
3886	  CONFIG_ENV_SIZE.
3887
3888- CONFIG_SYS_SPI_INIT_OFFSET
3889
3890	Defines offset to the initial SPI buffer area in DPRAM. The
3891	area is used at an early stage (ROM part) if the environment
3892	is configured to reside in the SPI EEPROM: We need a 520 byte
3893	scratch DPRAM area. It is used between the two initialization
3894	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3895	to be a good choice since it makes it far enough from the
3896	start of the data area as well as from the stack pointer.
3897
3898Please note that the environment is read-only until the monitor
3899has been relocated to RAM and a RAM copy of the environment has been
3900created; also, when using EEPROM you will have to use getenv_f()
3901until then to read environment variables.
3902
3903The environment is protected by a CRC32 checksum. Before the monitor
3904is relocated into RAM, as a result of a bad CRC you will be working
3905with the compiled-in default environment - *silently*!!! [This is
3906necessary, because the first environment variable we need is the
3907"baudrate" setting for the console - if we have a bad CRC, we don't
3908have any device yet where we could complain.]
3909
3910Note: once the monitor has been relocated, then it will complain if
3911the default environment is used; a new CRC is computed as soon as you
3912use the "saveenv" command to store a valid environment.
3913
3914- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3915		Echo the inverted Ethernet link state to the fault LED.
3916
3917		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3918		      also needs to be defined.
3919
3920- CONFIG_SYS_FAULT_MII_ADDR:
3921		MII address of the PHY to check for the Ethernet link state.
3922
3923- CONFIG_NS16550_MIN_FUNCTIONS:
3924		Define this if you desire to only have use of the NS16550_init
3925		and NS16550_putc functions for the serial driver located at
3926		drivers/serial/ns16550.c.  This option is useful for saving
3927		space for already greatly restricted images, including but not
3928		limited to NAND_SPL configurations.
3929
3930- CONFIG_DISPLAY_BOARDINFO
3931		Display information about the board that U-Boot is running on
3932		when U-Boot starts up. The board function checkboard() is called
3933		to do this.
3934
3935- CONFIG_DISPLAY_BOARDINFO_LATE
3936		Similar to the previous option, but display this information
3937		later, once stdio is running and output goes to the LCD, if
3938		present.
3939
3940Low Level (hardware related) configuration options:
3941---------------------------------------------------
3942
3943- CONFIG_SYS_CACHELINE_SIZE:
3944		Cache Line Size of the CPU.
3945
3946- CONFIG_SYS_DEFAULT_IMMR:
3947		Default address of the IMMR after system reset.
3948
3949		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3950		and RPXsuper) to be able to adjust the position of
3951		the IMMR register after a reset.
3952
3953- CONFIG_SYS_CCSRBAR_DEFAULT:
3954		Default (power-on reset) physical address of CCSR on Freescale
3955		PowerPC SOCs.
3956
3957- CONFIG_SYS_CCSRBAR:
3958		Virtual address of CCSR.  On a 32-bit build, this is typically
3959		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3960
3961		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3962		for cross-platform code that uses that macro instead.
3963
3964- CONFIG_SYS_CCSRBAR_PHYS:
3965		Physical address of CCSR.  CCSR can be relocated to a new
3966		physical address, if desired.  In this case, this macro should
3967		be set to that address.	 Otherwise, it should be set to the
3968		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3969		is typically relocated on 36-bit builds.  It is recommended
3970		that this macro be defined via the _HIGH and _LOW macros:
3971
3972		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3973			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3974
3975- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3976		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3977		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3978		used in assembly code, so it must not contain typecasts or
3979		integer size suffixes (e.g. "ULL").
3980
3981- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3982		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3983		used in assembly code, so it must not contain typecasts or
3984		integer size suffixes (e.g. "ULL").
3985
3986- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3987		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3988		forced to a value that ensures that CCSR is not relocated.
3989
3990- Floppy Disk Support:
3991		CONFIG_SYS_FDC_DRIVE_NUMBER
3992
3993		the default drive number (default value 0)
3994
3995		CONFIG_SYS_ISA_IO_STRIDE
3996
3997		defines the spacing between FDC chipset registers
3998		(default value 1)
3999
4000		CONFIG_SYS_ISA_IO_OFFSET
4001
4002		defines the offset of register from address. It
4003		depends on which part of the data bus is connected to
4004		the FDC chipset. (default value 0)
4005
4006		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
4007		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
4008		default value.
4009
4010		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
4011		fdc_hw_init() is called at the beginning of the FDC
4012		setup. fdc_hw_init() must be provided by the board
4013		source code. It is used to make hardware dependant
4014		initializations.
4015
4016- CONFIG_IDE_AHB:
4017		Most IDE controllers were designed to be connected with PCI
4018		interface. Only few of them were designed for AHB interface.
4019		When software is doing ATA command and data transfer to
4020		IDE devices through IDE-AHB controller, some additional
4021		registers accessing to these kind of IDE-AHB controller
4022		is requierd.
4023
4024- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
4025		DO NOT CHANGE unless you know exactly what you're
4026		doing! (11-4) [MPC8xx/82xx systems only]
4027
4028- CONFIG_SYS_INIT_RAM_ADDR:
4029
4030		Start address of memory area that can be used for
4031		initial data and stack; please note that this must be
4032		writable memory that is working WITHOUT special
4033		initialization, i. e. you CANNOT use normal RAM which
4034		will become available only after programming the
4035		memory controller and running certain initialization
4036		sequences.
4037
4038		U-Boot uses the following memory types:
4039		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
4040		- MPC824X: data cache
4041		- PPC4xx:  data cache
4042
4043- CONFIG_SYS_GBL_DATA_OFFSET:
4044
4045		Offset of the initial data structure in the memory
4046		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
4047		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
4048		data is located at the end of the available space
4049		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
4050		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
4051		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
4052		CONFIG_SYS_GBL_DATA_OFFSET) downward.
4053
4054	Note:
4055		On the MPC824X (or other systems that use the data
4056		cache for initial memory) the address chosen for
4057		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4058		point to an otherwise UNUSED address space between
4059		the top of RAM and the start of the PCI space.
4060
4061- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4062
4063- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4064
4065- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4066
4067- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4068
4069- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4070
4071- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4072
4073- CONFIG_SYS_OR_TIMING_SDRAM:
4074		SDRAM timing
4075
4076- CONFIG_SYS_MAMR_PTA:
4077		periodic timer for refresh
4078
4079- CONFIG_SYS_DER:	Debug Event Register (37-47)
4080
4081- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4082  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4083  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4084  CONFIG_SYS_BR1_PRELIM:
4085		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4086
4087- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4088  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4089  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4090		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4091
4092- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4093  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4094		Machine Mode Register and Memory Periodic Timer
4095		Prescaler definitions (SDRAM timing)
4096
4097- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4098		enable I2C microcode relocation patch (MPC8xx);
4099		define relocation offset in DPRAM [DSP2]
4100
4101- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4102		enable SMC microcode relocation patch (MPC8xx);
4103		define relocation offset in DPRAM [SMC1]
4104
4105- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4106		enable SPI microcode relocation patch (MPC8xx);
4107		define relocation offset in DPRAM [SCC4]
4108
4109- CONFIG_SYS_USE_OSCCLK:
4110		Use OSCM clock mode on MBX8xx board. Be careful,
4111		wrong setting might damage your board. Read
4112		doc/README.MBX before setting this variable!
4113
4114- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4115		Offset of the bootmode word in DPRAM used by post
4116		(Power On Self Tests). This definition overrides
4117		#define'd default value in commproc.h resp.
4118		cpm_8260.h.
4119
4120- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4121  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4122  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4123  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4124  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4125  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4126  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4127  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4128		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4129
4130- CONFIG_PCI_DISABLE_PCIE:
4131		Disable PCI-Express on systems where it is supported but not
4132		required.
4133
4134- CONFIG_PCI_ENUM_ONLY
4135		Only scan through and get the devices on the busses.
4136		Don't do any setup work, presumably because someone or
4137		something has already done it, and we don't need to do it
4138		a second time.	Useful for platforms that are pre-booted
4139		by coreboot or similar.
4140
4141- CONFIG_PCI_INDIRECT_BRIDGE:
4142		Enable support for indirect PCI bridges.
4143
4144- CONFIG_SYS_SRIO:
4145		Chip has SRIO or not
4146
4147- CONFIG_SRIO1:
4148		Board has SRIO 1 port available
4149
4150- CONFIG_SRIO2:
4151		Board has SRIO 2 port available
4152
4153- CONFIG_SRIO_PCIE_BOOT_MASTER
4154		Board can support master function for Boot from SRIO and PCIE
4155
4156- CONFIG_SYS_SRIOn_MEM_VIRT:
4157		Virtual Address of SRIO port 'n' memory region
4158
4159- CONFIG_SYS_SRIOn_MEM_PHYS:
4160		Physical Address of SRIO port 'n' memory region
4161
4162- CONFIG_SYS_SRIOn_MEM_SIZE:
4163		Size of SRIO port 'n' memory region
4164
4165- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4166		Defined to tell the NAND controller that the NAND chip is using
4167		a 16 bit bus.
4168		Not all NAND drivers use this symbol.
4169		Example of drivers that use it:
4170		- drivers/mtd/nand/ndfc.c
4171		- drivers/mtd/nand/mxc_nand.c
4172
4173- CONFIG_SYS_NDFC_EBC0_CFG
4174		Sets the EBC0_CFG register for the NDFC. If not defined
4175		a default value will be used.
4176
4177- CONFIG_SPD_EEPROM
4178		Get DDR timing information from an I2C EEPROM. Common
4179		with pluggable memory modules such as SODIMMs
4180
4181  SPD_EEPROM_ADDRESS
4182		I2C address of the SPD EEPROM
4183
4184- CONFIG_SYS_SPD_BUS_NUM
4185		If SPD EEPROM is on an I2C bus other than the first
4186		one, specify here. Note that the value must resolve
4187		to something your driver can deal with.
4188
4189- CONFIG_SYS_DDR_RAW_TIMING
4190		Get DDR timing information from other than SPD. Common with
4191		soldered DDR chips onboard without SPD. DDR raw timing
4192		parameters are extracted from datasheet and hard-coded into
4193		header files or board specific files.
4194
4195- CONFIG_FSL_DDR_INTERACTIVE
4196		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4197
4198- CONFIG_SYS_83XX_DDR_USES_CS0
4199		Only for 83xx systems. If specified, then DDR should
4200		be configured using CS0 and CS1 instead of CS2 and CS3.
4201
4202- CONFIG_ETHER_ON_FEC[12]
4203		Define to enable FEC[12] on a 8xx series processor.
4204
4205- CONFIG_FEC[12]_PHY
4206		Define to the hardcoded PHY address which corresponds
4207		to the given FEC; i. e.
4208			#define CONFIG_FEC1_PHY 4
4209		means that the PHY with address 4 is connected to FEC1
4210
4211		When set to -1, means to probe for first available.
4212
4213- CONFIG_FEC[12]_PHY_NORXERR
4214		The PHY does not have a RXERR line (RMII only).
4215		(so program the FEC to ignore it).
4216
4217- CONFIG_RMII
4218		Enable RMII mode for all FECs.
4219		Note that this is a global option, we can't
4220		have one FEC in standard MII mode and another in RMII mode.
4221
4222- CONFIG_CRC32_VERIFY
4223		Add a verify option to the crc32 command.
4224		The syntax is:
4225
4226		=> crc32 -v <address> <count> <crc32>
4227
4228		Where address/count indicate a memory area
4229		and crc32 is the correct crc32 which the
4230		area should have.
4231
4232- CONFIG_LOOPW
4233		Add the "loopw" memory command. This only takes effect if
4234		the memory commands are activated globally (CONFIG_CMD_MEM).
4235
4236- CONFIG_MX_CYCLIC
4237		Add the "mdc" and "mwc" memory commands. These are cyclic
4238		"md/mw" commands.
4239		Examples:
4240
4241		=> mdc.b 10 4 500
4242		This command will print 4 bytes (10,11,12,13) each 500 ms.
4243
4244		=> mwc.l 100 12345678 10
4245		This command will write 12345678 to address 100 all 10 ms.
4246
4247		This only takes effect if the memory commands are activated
4248		globally (CONFIG_CMD_MEM).
4249
4250- CONFIG_SKIP_LOWLEVEL_INIT
4251		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4252		low level initializations (like setting up the memory
4253		controller) are omitted and/or U-Boot does not
4254		relocate itself into RAM.
4255
4256		Normally this variable MUST NOT be defined. The only
4257		exception is when U-Boot is loaded (to RAM) by some
4258		other boot loader or by a debugger which performs
4259		these initializations itself.
4260
4261- CONFIG_SPL_BUILD
4262		Modifies the behaviour of start.S when compiling a loader
4263		that is executed before the actual U-Boot. E.g. when
4264		compiling a NAND SPL.
4265
4266- CONFIG_TPL_BUILD
4267		Modifies the behaviour of start.S  when compiling a loader
4268		that is executed after the SPL and before the actual U-Boot.
4269		It is loaded by the SPL.
4270
4271- CONFIG_SYS_MPC85XX_NO_RESETVEC
4272		Only for 85xx systems. If this variable is specified, the section
4273		.resetvec is not kept and the section .bootpg is placed in the
4274		previous 4k of the .text section.
4275
4276- CONFIG_ARCH_MAP_SYSMEM
4277		Generally U-Boot (and in particular the md command) uses
4278		effective address. It is therefore not necessary to regard
4279		U-Boot address as virtual addresses that need to be translated
4280		to physical addresses. However, sandbox requires this, since
4281		it maintains its own little RAM buffer which contains all
4282		addressable memory. This option causes some memory accesses
4283		to be mapped through map_sysmem() / unmap_sysmem().
4284
4285- CONFIG_USE_ARCH_MEMCPY
4286  CONFIG_USE_ARCH_MEMSET
4287		If these options are used a optimized version of memcpy/memset will
4288		be used if available. These functions may be faster under some
4289		conditions but may increase the binary size.
4290
4291- CONFIG_X86_RESET_VECTOR
4292		If defined, the x86 reset vector code is included. This is not
4293		needed when U-Boot is running from Coreboot.
4294
4295- CONFIG_SYS_MPUCLK
4296		Defines the MPU clock speed (in MHz).
4297
4298		NOTE : currently only supported on AM335x platforms.
4299
4300Freescale QE/FMAN Firmware Support:
4301-----------------------------------
4302
4303The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4304loading of "firmware", which is encoded in the QE firmware binary format.
4305This firmware often needs to be loaded during U-Boot booting, so macros
4306are used to identify the storage device (NOR flash, SPI, etc) and the address
4307within that device.
4308
4309- CONFIG_SYS_QE_FMAN_FW_ADDR
4310	The address in the storage device where the firmware is located.  The
4311	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4312	is also specified.
4313
4314- CONFIG_SYS_QE_FMAN_FW_LENGTH
4315	The maximum possible size of the firmware.  The firmware binary format
4316	has a field that specifies the actual size of the firmware, but it
4317	might not be possible to read any part of the firmware unless some
4318	local storage is allocated to hold the entire firmware first.
4319
4320- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4321	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4322	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4323	virtual address in NOR flash.
4324
4325- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4326	Specifies that QE/FMAN firmware is located in NAND flash.
4327	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4328
4329- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4330	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4331	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4332
4333- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4334	Specifies that QE/FMAN firmware is located on the primary SPI
4335	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4336
4337- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4338	Specifies that QE/FMAN firmware is located in the remote (master)
4339	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4340	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4341	window->master inbound window->master LAW->the ucode address in
4342	master's memory space.
4343
4344Building the Software:
4345======================
4346
4347Building U-Boot has been tested in several native build environments
4348and in many different cross environments. Of course we cannot support
4349all possibly existing versions of cross development tools in all
4350(potentially obsolete) versions. In case of tool chain problems we
4351recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4352which is extensively used to build and test U-Boot.
4353
4354If you are not using a native environment, it is assumed that you
4355have GNU cross compiling tools available in your path. In this case,
4356you must set the environment variable CROSS_COMPILE in your shell.
4357Note that no changes to the Makefile or any other source files are
4358necessary. For example using the ELDK on a 4xx CPU, please enter:
4359
4360	$ CROSS_COMPILE=ppc_4xx-
4361	$ export CROSS_COMPILE
4362
4363Note: If you wish to generate Windows versions of the utilities in
4364      the tools directory you can use the MinGW toolchain
4365      (http://www.mingw.org).  Set your HOST tools to the MinGW
4366      toolchain and execute 'make tools'.  For example:
4367
4368       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4369
4370      Binaries such as tools/mkimage.exe will be created which can
4371      be executed on computers running Windows.
4372
4373U-Boot is intended to be simple to build. After installing the
4374sources you must configure U-Boot for one specific board type. This
4375is done by typing:
4376
4377	make NAME_config
4378
4379where "NAME_config" is the name of one of the existing configu-
4380rations; see boards.cfg for supported names.
4381
4382Note: for some board special configuration names may exist; check if
4383      additional information is available from the board vendor; for
4384      instance, the TQM823L systems are available without (standard)
4385      or with LCD support. You can select such additional "features"
4386      when choosing the configuration, i. e.
4387
4388      make TQM823L_config
4389	- will configure for a plain TQM823L, i. e. no LCD support
4390
4391      make TQM823L_LCD_config
4392	- will configure for a TQM823L with U-Boot console on LCD
4393
4394      etc.
4395
4396
4397Finally, type "make all", and you should get some working U-Boot
4398images ready for download to / installation on your system:
4399
4400- "u-boot.bin" is a raw binary image
4401- "u-boot" is an image in ELF binary format
4402- "u-boot.srec" is in Motorola S-Record format
4403
4404By default the build is performed locally and the objects are saved
4405in the source directory. One of the two methods can be used to change
4406this behavior and build U-Boot to some external directory:
4407
44081. Add O= to the make command line invocations:
4409
4410	make O=/tmp/build distclean
4411	make O=/tmp/build NAME_config
4412	make O=/tmp/build all
4413
44142. Set environment variable BUILD_DIR to point to the desired location:
4415
4416	export BUILD_DIR=/tmp/build
4417	make distclean
4418	make NAME_config
4419	make all
4420
4421Note that the command line "O=" setting overrides the BUILD_DIR environment
4422variable.
4423
4424
4425Please be aware that the Makefiles assume you are using GNU make, so
4426for instance on NetBSD you might need to use "gmake" instead of
4427native "make".
4428
4429
4430If the system board that you have is not listed, then you will need
4431to port U-Boot to your hardware platform. To do this, follow these
4432steps:
4433
44341.  Add a new configuration option for your board to the toplevel
4435    "boards.cfg" file, using the existing entries as examples.
4436    Follow the instructions there to keep the boards in order.
44372.  Create a new directory to hold your board specific code. Add any
4438    files you need. In your board directory, you will need at least
4439    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
44403.  Create a new configuration file "include/configs/<board>.h" for
4441    your board
44423.  If you're porting U-Boot to a new CPU, then also create a new
4443    directory to hold your CPU specific code. Add any files you need.
44444.  Run "make <board>_config" with your new name.
44455.  Type "make", and you should get a working "u-boot.srec" file
4446    to be installed on your target system.
44476.  Debug and solve any problems that might arise.
4448    [Of course, this last step is much harder than it sounds.]
4449
4450
4451Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4452==============================================================
4453
4454If you have modified U-Boot sources (for instance added a new board
4455or support for new devices, a new CPU, etc.) you are expected to
4456provide feedback to the other developers. The feedback normally takes
4457the form of a "patch", i. e. a context diff against a certain (latest
4458official or latest in the git repository) version of U-Boot sources.
4459
4460But before you submit such a patch, please verify that your modifi-
4461cation did not break existing code. At least make sure that *ALL* of
4462the supported boards compile WITHOUT ANY compiler warnings. To do so,
4463just run the "MAKEALL" script, which will configure and build U-Boot
4464for ALL supported system. Be warned, this will take a while. You can
4465select which (cross) compiler to use by passing a `CROSS_COMPILE'
4466environment variable to the script, i. e. to use the ELDK cross tools
4467you can type
4468
4469	CROSS_COMPILE=ppc_8xx- MAKEALL
4470
4471or to build on a native PowerPC system you can type
4472
4473	CROSS_COMPILE=' ' MAKEALL
4474
4475When using the MAKEALL script, the default behaviour is to build
4476U-Boot in the source directory. This location can be changed by
4477setting the BUILD_DIR environment variable. Also, for each target
4478built, the MAKEALL script saves two log files (<target>.ERR and
4479<target>.MAKEALL) in the <source dir>/LOG directory. This default
4480location can be changed by setting the MAKEALL_LOGDIR environment
4481variable. For example:
4482
4483	export BUILD_DIR=/tmp/build
4484	export MAKEALL_LOGDIR=/tmp/log
4485	CROSS_COMPILE=ppc_8xx- MAKEALL
4486
4487With the above settings build objects are saved in the /tmp/build,
4488log files are saved in the /tmp/log and the source tree remains clean
4489during the whole build process.
4490
4491
4492See also "U-Boot Porting Guide" below.
4493
4494
4495Monitor Commands - Overview:
4496============================
4497
4498go	- start application at address 'addr'
4499run	- run commands in an environment variable
4500bootm	- boot application image from memory
4501bootp	- boot image via network using BootP/TFTP protocol
4502bootz   - boot zImage from memory
4503tftpboot- boot image via network using TFTP protocol
4504	       and env variables "ipaddr" and "serverip"
4505	       (and eventually "gatewayip")
4506tftpput - upload a file via network using TFTP protocol
4507rarpboot- boot image via network using RARP/TFTP protocol
4508diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4509loads	- load S-Record file over serial line
4510loadb	- load binary file over serial line (kermit mode)
4511md	- memory display
4512mm	- memory modify (auto-incrementing)
4513nm	- memory modify (constant address)
4514mw	- memory write (fill)
4515cp	- memory copy
4516cmp	- memory compare
4517crc32	- checksum calculation
4518i2c	- I2C sub-system
4519sspi	- SPI utility commands
4520base	- print or set address offset
4521printenv- print environment variables
4522setenv	- set environment variables
4523saveenv - save environment variables to persistent storage
4524protect - enable or disable FLASH write protection
4525erase	- erase FLASH memory
4526flinfo	- print FLASH memory information
4527nand	- NAND memory operations (see doc/README.nand)
4528bdinfo	- print Board Info structure
4529iminfo	- print header information for application image
4530coninfo - print console devices and informations
4531ide	- IDE sub-system
4532loop	- infinite loop on address range
4533loopw	- infinite write loop on address range
4534mtest	- simple RAM test
4535icache	- enable or disable instruction cache
4536dcache	- enable or disable data cache
4537reset	- Perform RESET of the CPU
4538echo	- echo args to console
4539version - print monitor version
4540help	- print online help
4541?	- alias for 'help'
4542
4543
4544Monitor Commands - Detailed Description:
4545========================================
4546
4547TODO.
4548
4549For now: just type "help <command>".
4550
4551
4552Environment Variables:
4553======================
4554
4555U-Boot supports user configuration using Environment Variables which
4556can be made persistent by saving to Flash memory.
4557
4558Environment Variables are set using "setenv", printed using
4559"printenv", and saved to Flash using "saveenv". Using "setenv"
4560without a value can be used to delete a variable from the
4561environment. As long as you don't save the environment you are
4562working with an in-memory copy. In case the Flash area containing the
4563environment is erased by accident, a default environment is provided.
4564
4565Some configuration options can be set using Environment Variables.
4566
4567List of environment variables (most likely not complete):
4568
4569  baudrate	- see CONFIG_BAUDRATE
4570
4571  bootdelay	- see CONFIG_BOOTDELAY
4572
4573  bootcmd	- see CONFIG_BOOTCOMMAND
4574
4575  bootargs	- Boot arguments when booting an RTOS image
4576
4577  bootfile	- Name of the image to load with TFTP
4578
4579  bootm_low	- Memory range available for image processing in the bootm
4580		  command can be restricted. This variable is given as
4581		  a hexadecimal number and defines lowest address allowed
4582		  for use by the bootm command. See also "bootm_size"
4583		  environment variable. Address defined by "bootm_low" is
4584		  also the base of the initial memory mapping for the Linux
4585		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4586		  bootm_mapsize.
4587
4588  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4589		  This variable is given as a hexadecimal number and it
4590		  defines the size of the memory region starting at base
4591		  address bootm_low that is accessible by the Linux kernel
4592		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4593		  as the default value if it is defined, and bootm_size is
4594		  used otherwise.
4595
4596  bootm_size	- Memory range available for image processing in the bootm
4597		  command can be restricted. This variable is given as
4598		  a hexadecimal number and defines the size of the region
4599		  allowed for use by the bootm command. See also "bootm_low"
4600		  environment variable.
4601
4602  updatefile	- Location of the software update file on a TFTP server, used
4603		  by the automatic software update feature. Please refer to
4604		  documentation in doc/README.update for more details.
4605
4606  autoload	- if set to "no" (any string beginning with 'n'),
4607		  "bootp" will just load perform a lookup of the
4608		  configuration from the BOOTP server, but not try to
4609		  load any image using TFTP
4610
4611  autostart	- if set to "yes", an image loaded using the "bootp",
4612		  "rarpboot", "tftpboot" or "diskboot" commands will
4613		  be automatically started (by internally calling
4614		  "bootm")
4615
4616		  If set to "no", a standalone image passed to the
4617		  "bootm" command will be copied to the load address
4618		  (and eventually uncompressed), but NOT be started.
4619		  This can be used to load and uncompress arbitrary
4620		  data.
4621
4622  fdt_high	- if set this restricts the maximum address that the
4623		  flattened device tree will be copied into upon boot.
4624		  For example, if you have a system with 1 GB memory
4625		  at physical address 0x10000000, while Linux kernel
4626		  only recognizes the first 704 MB as low memory, you
4627		  may need to set fdt_high as 0x3C000000 to have the
4628		  device tree blob be copied to the maximum address
4629		  of the 704 MB low memory, so that Linux kernel can
4630		  access it during the boot procedure.
4631
4632		  If this is set to the special value 0xFFFFFFFF then
4633		  the fdt will not be copied at all on boot.  For this
4634		  to work it must reside in writable memory, have
4635		  sufficient padding on the end of it for u-boot to
4636		  add the information it needs into it, and the memory
4637		  must be accessible by the kernel.
4638
4639  fdtcontroladdr- if set this is the address of the control flattened
4640		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4641		  defined.
4642
4643  i2cfast	- (PPC405GP|PPC405EP only)
4644		  if set to 'y' configures Linux I2C driver for fast
4645		  mode (400kHZ). This environment variable is used in
4646		  initialization code. So, for changes to be effective
4647		  it must be saved and board must be reset.
4648
4649  initrd_high	- restrict positioning of initrd images:
4650		  If this variable is not set, initrd images will be
4651		  copied to the highest possible address in RAM; this
4652		  is usually what you want since it allows for
4653		  maximum initrd size. If for some reason you want to
4654		  make sure that the initrd image is loaded below the
4655		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4656		  variable to a value of "no" or "off" or "0".
4657		  Alternatively, you can set it to a maximum upper
4658		  address to use (U-Boot will still check that it
4659		  does not overwrite the U-Boot stack and data).
4660
4661		  For instance, when you have a system with 16 MB
4662		  RAM, and want to reserve 4 MB from use by Linux,
4663		  you can do this by adding "mem=12M" to the value of
4664		  the "bootargs" variable. However, now you must make
4665		  sure that the initrd image is placed in the first
4666		  12 MB as well - this can be done with
4667
4668		  setenv initrd_high 00c00000
4669
4670		  If you set initrd_high to 0xFFFFFFFF, this is an
4671		  indication to U-Boot that all addresses are legal
4672		  for the Linux kernel, including addresses in flash
4673		  memory. In this case U-Boot will NOT COPY the
4674		  ramdisk at all. This may be useful to reduce the
4675		  boot time on your system, but requires that this
4676		  feature is supported by your Linux kernel.
4677
4678  ipaddr	- IP address; needed for tftpboot command
4679
4680  loadaddr	- Default load address for commands like "bootp",
4681		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4682
4683  loads_echo	- see CONFIG_LOADS_ECHO
4684
4685  serverip	- TFTP server IP address; needed for tftpboot command
4686
4687  bootretry	- see CONFIG_BOOT_RETRY_TIME
4688
4689  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4690
4691  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4692
4693  ethprime	- controls which interface is used first.
4694
4695  ethact	- controls which interface is currently active.
4696		  For example you can do the following
4697
4698		  => setenv ethact FEC
4699		  => ping 192.168.0.1 # traffic sent on FEC
4700		  => setenv ethact SCC
4701		  => ping 10.0.0.1 # traffic sent on SCC
4702
4703  ethrotate	- When set to "no" U-Boot does not go through all
4704		  available network interfaces.
4705		  It just stays at the currently selected interface.
4706
4707  netretry	- When set to "no" each network operation will
4708		  either succeed or fail without retrying.
4709		  When set to "once" the network operation will
4710		  fail when all the available network interfaces
4711		  are tried once without success.
4712		  Useful on scripts which control the retry operation
4713		  themselves.
4714
4715  npe_ucode	- set load address for the NPE microcode
4716
4717  silent_linux  - If set then linux will be told to boot silently, by
4718		  changing the console to be empty. If "yes" it will be
4719		  made silent. If "no" it will not be made silent. If
4720		  unset, then it will be made silent if the U-Boot console
4721		  is silent.
4722
4723  tftpsrcport	- If this is set, the value is used for TFTP's
4724		  UDP source port.
4725
4726  tftpdstport	- If this is set, the value is used for TFTP's UDP
4727		  destination port instead of the Well Know Port 69.
4728
4729  tftpblocksize - Block size to use for TFTP transfers; if not set,
4730		  we use the TFTP server's default block size
4731
4732  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4733		  seconds, minimum value is 1000 = 1 second). Defines
4734		  when a packet is considered to be lost so it has to
4735		  be retransmitted. The default is 5000 = 5 seconds.
4736		  Lowering this value may make downloads succeed
4737		  faster in networks with high packet loss rates or
4738		  with unreliable TFTP servers.
4739
4740  vlan		- When set to a value < 4095 the traffic over
4741		  Ethernet is encapsulated/received over 802.1q
4742		  VLAN tagged frames.
4743
4744The following image location variables contain the location of images
4745used in booting. The "Image" column gives the role of the image and is
4746not an environment variable name. The other columns are environment
4747variable names. "File Name" gives the name of the file on a TFTP
4748server, "RAM Address" gives the location in RAM the image will be
4749loaded to, and "Flash Location" gives the image's address in NOR
4750flash or offset in NAND flash.
4751
4752*Note* - these variables don't have to be defined for all boards, some
4753boards currenlty use other variables for these purposes, and some
4754boards use these variables for other purposes.
4755
4756Image		    File Name	     RAM Address       Flash Location
4757-----		    ---------	     -----------       --------------
4758u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4759Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4760device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4761ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4762
4763The following environment variables may be used and automatically
4764updated by the network boot commands ("bootp" and "rarpboot"),
4765depending the information provided by your boot server:
4766
4767  bootfile	- see above
4768  dnsip		- IP address of your Domain Name Server
4769  dnsip2	- IP address of your secondary Domain Name Server
4770  gatewayip	- IP address of the Gateway (Router) to use
4771  hostname	- Target hostname
4772  ipaddr	- see above
4773  netmask	- Subnet Mask
4774  rootpath	- Pathname of the root filesystem on the NFS server
4775  serverip	- see above
4776
4777
4778There are two special Environment Variables:
4779
4780  serial#	- contains hardware identification information such
4781		  as type string and/or serial number
4782  ethaddr	- Ethernet address
4783
4784These variables can be set only once (usually during manufacturing of
4785the board). U-Boot refuses to delete or overwrite these variables
4786once they have been set once.
4787
4788
4789Further special Environment Variables:
4790
4791  ver		- Contains the U-Boot version string as printed
4792		  with the "version" command. This variable is
4793		  readonly (see CONFIG_VERSION_VARIABLE).
4794
4795
4796Please note that changes to some configuration parameters may take
4797only effect after the next boot (yes, that's just like Windoze :-).
4798
4799
4800Callback functions for environment variables:
4801---------------------------------------------
4802
4803For some environment variables, the behavior of u-boot needs to change
4804when their values are changed.  This functionailty allows functions to
4805be associated with arbitrary variables.  On creation, overwrite, or
4806deletion, the callback will provide the opportunity for some side
4807effect to happen or for the change to be rejected.
4808
4809The callbacks are named and associated with a function using the
4810U_BOOT_ENV_CALLBACK macro in your board or driver code.
4811
4812These callbacks are associated with variables in one of two ways.  The
4813static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4814in the board configuration to a string that defines a list of
4815associations.  The list must be in the following format:
4816
4817	entry = variable_name[:callback_name]
4818	list = entry[,list]
4819
4820If the callback name is not specified, then the callback is deleted.
4821Spaces are also allowed anywhere in the list.
4822
4823Callbacks can also be associated by defining the ".callbacks" variable
4824with the same list format above.  Any association in ".callbacks" will
4825override any association in the static list. You can define
4826CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4827".callbacks" envirnoment variable in the default or embedded environment.
4828
4829
4830Command Line Parsing:
4831=====================
4832
4833There are two different command line parsers available with U-Boot:
4834the old "simple" one, and the much more powerful "hush" shell:
4835
4836Old, simple command line parser:
4837--------------------------------
4838
4839- supports environment variables (through setenv / saveenv commands)
4840- several commands on one line, separated by ';'
4841- variable substitution using "... ${name} ..." syntax
4842- special characters ('$', ';') can be escaped by prefixing with '\',
4843  for example:
4844	setenv bootcmd bootm \${address}
4845- You can also escape text by enclosing in single apostrophes, for example:
4846	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4847
4848Hush shell:
4849-----------
4850
4851- similar to Bourne shell, with control structures like
4852  if...then...else...fi, for...do...done; while...do...done,
4853  until...do...done, ...
4854- supports environment ("global") variables (through setenv / saveenv
4855  commands) and local shell variables (through standard shell syntax
4856  "name=value"); only environment variables can be used with "run"
4857  command
4858
4859General rules:
4860--------------
4861
4862(1) If a command line (or an environment variable executed by a "run"
4863    command) contains several commands separated by semicolon, and
4864    one of these commands fails, then the remaining commands will be
4865    executed anyway.
4866
4867(2) If you execute several variables with one call to run (i. e.
4868    calling run with a list of variables as arguments), any failing
4869    command will cause "run" to terminate, i. e. the remaining
4870    variables are not executed.
4871
4872Note for Redundant Ethernet Interfaces:
4873=======================================
4874
4875Some boards come with redundant Ethernet interfaces; U-Boot supports
4876such configurations and is capable of automatic selection of a
4877"working" interface when needed. MAC assignment works as follows:
4878
4879Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4880MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4881"eth1addr" (=>eth1), "eth2addr", ...
4882
4883If the network interface stores some valid MAC address (for instance
4884in SROM), this is used as default address if there is NO correspon-
4885ding setting in the environment; if the corresponding environment
4886variable is set, this overrides the settings in the card; that means:
4887
4888o If the SROM has a valid MAC address, and there is no address in the
4889  environment, the SROM's address is used.
4890
4891o If there is no valid address in the SROM, and a definition in the
4892  environment exists, then the value from the environment variable is
4893  used.
4894
4895o If both the SROM and the environment contain a MAC address, and
4896  both addresses are the same, this MAC address is used.
4897
4898o If both the SROM and the environment contain a MAC address, and the
4899  addresses differ, the value from the environment is used and a
4900  warning is printed.
4901
4902o If neither SROM nor the environment contain a MAC address, an error
4903  is raised.
4904
4905If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4906will be programmed into hardware as part of the initialization process.	 This
4907may be skipped by setting the appropriate 'ethmacskip' environment variable.
4908The naming convention is as follows:
4909"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4910
4911Image Formats:
4912==============
4913
4914U-Boot is capable of booting (and performing other auxiliary operations on)
4915images in two formats:
4916
4917New uImage format (FIT)
4918-----------------------
4919
4920Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4921to Flattened Device Tree). It allows the use of images with multiple
4922components (several kernels, ramdisks, etc.), with contents protected by
4923SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4924
4925
4926Old uImage format
4927-----------------
4928
4929Old image format is based on binary files which can be basically anything,
4930preceded by a special header; see the definitions in include/image.h for
4931details; basically, the header defines the following image properties:
4932
4933* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4934  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4935  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4936  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4937  INTEGRITY).
4938* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4939  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4940  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4941* Compression Type (uncompressed, gzip, bzip2)
4942* Load Address
4943* Entry Point
4944* Image Name
4945* Image Timestamp
4946
4947The header is marked by a special Magic Number, and both the header
4948and the data portions of the image are secured against corruption by
4949CRC32 checksums.
4950
4951
4952Linux Support:
4953==============
4954
4955Although U-Boot should support any OS or standalone application
4956easily, the main focus has always been on Linux during the design of
4957U-Boot.
4958
4959U-Boot includes many features that so far have been part of some
4960special "boot loader" code within the Linux kernel. Also, any
4961"initrd" images to be used are no longer part of one big Linux image;
4962instead, kernel and "initrd" are separate images. This implementation
4963serves several purposes:
4964
4965- the same features can be used for other OS or standalone
4966  applications (for instance: using compressed images to reduce the
4967  Flash memory footprint)
4968
4969- it becomes much easier to port new Linux kernel versions because
4970  lots of low-level, hardware dependent stuff are done by U-Boot
4971
4972- the same Linux kernel image can now be used with different "initrd"
4973  images; of course this also means that different kernel images can
4974  be run with the same "initrd". This makes testing easier (you don't
4975  have to build a new "zImage.initrd" Linux image when you just
4976  change a file in your "initrd"). Also, a field-upgrade of the
4977  software is easier now.
4978
4979
4980Linux HOWTO:
4981============
4982
4983Porting Linux to U-Boot based systems:
4984---------------------------------------
4985
4986U-Boot cannot save you from doing all the necessary modifications to
4987configure the Linux device drivers for use with your target hardware
4988(no, we don't intend to provide a full virtual machine interface to
4989Linux :-).
4990
4991But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4992
4993Just make sure your machine specific header file (for instance
4994include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4995Information structure as we define in include/asm-<arch>/u-boot.h,
4996and make sure that your definition of IMAP_ADDR uses the same value
4997as your U-Boot configuration in CONFIG_SYS_IMMR.
4998
4999
5000Configuring the Linux kernel:
5001-----------------------------
5002
5003No specific requirements for U-Boot. Make sure you have some root
5004device (initial ramdisk, NFS) for your target system.
5005
5006
5007Building a Linux Image:
5008-----------------------
5009
5010With U-Boot, "normal" build targets like "zImage" or "bzImage" are
5011not used. If you use recent kernel source, a new build target
5012"uImage" will exist which automatically builds an image usable by
5013U-Boot. Most older kernels also have support for a "pImage" target,
5014which was introduced for our predecessor project PPCBoot and uses a
5015100% compatible format.
5016
5017Example:
5018
5019	make TQM850L_config
5020	make oldconfig
5021	make dep
5022	make uImage
5023
5024The "uImage" build target uses a special tool (in 'tools/mkimage') to
5025encapsulate a compressed Linux kernel image with header	 information,
5026CRC32 checksum etc. for use with U-Boot. This is what we are doing:
5027
5028* build a standard "vmlinux" kernel image (in ELF binary format):
5029
5030* convert the kernel into a raw binary image:
5031
5032	${CROSS_COMPILE}-objcopy -O binary \
5033				 -R .note -R .comment \
5034				 -S vmlinux linux.bin
5035
5036* compress the binary image:
5037
5038	gzip -9 linux.bin
5039
5040* package compressed binary image for U-Boot:
5041
5042	mkimage -A ppc -O linux -T kernel -C gzip \
5043		-a 0 -e 0 -n "Linux Kernel Image" \
5044		-d linux.bin.gz uImage
5045
5046
5047The "mkimage" tool can also be used to create ramdisk images for use
5048with U-Boot, either separated from the Linux kernel image, or
5049combined into one file. "mkimage" encapsulates the images with a 64
5050byte header containing information about target architecture,
5051operating system, image type, compression method, entry points, time
5052stamp, CRC32 checksums, etc.
5053
5054"mkimage" can be called in two ways: to verify existing images and
5055print the header information, or to build new images.
5056
5057In the first form (with "-l" option) mkimage lists the information
5058contained in the header of an existing U-Boot image; this includes
5059checksum verification:
5060
5061	tools/mkimage -l image
5062	  -l ==> list image header information
5063
5064The second form (with "-d" option) is used to build a U-Boot image
5065from a "data file" which is used as image payload:
5066
5067	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5068		      -n name -d data_file image
5069	  -A ==> set architecture to 'arch'
5070	  -O ==> set operating system to 'os'
5071	  -T ==> set image type to 'type'
5072	  -C ==> set compression type 'comp'
5073	  -a ==> set load address to 'addr' (hex)
5074	  -e ==> set entry point to 'ep' (hex)
5075	  -n ==> set image name to 'name'
5076	  -d ==> use image data from 'datafile'
5077
5078Right now, all Linux kernels for PowerPC systems use the same load
5079address (0x00000000), but the entry point address depends on the
5080kernel version:
5081
5082- 2.2.x kernels have the entry point at 0x0000000C,
5083- 2.3.x and later kernels have the entry point at 0x00000000.
5084
5085So a typical call to build a U-Boot image would read:
5086
5087	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5088	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5089	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5090	> examples/uImage.TQM850L
5091	Image Name:   2.4.4 kernel for TQM850L
5092	Created:      Wed Jul 19 02:34:59 2000
5093	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5094	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5095	Load Address: 0x00000000
5096	Entry Point:  0x00000000
5097
5098To verify the contents of the image (or check for corruption):
5099
5100	-> tools/mkimage -l examples/uImage.TQM850L
5101	Image Name:   2.4.4 kernel for TQM850L
5102	Created:      Wed Jul 19 02:34:59 2000
5103	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5104	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5105	Load Address: 0x00000000
5106	Entry Point:  0x00000000
5107
5108NOTE: for embedded systems where boot time is critical you can trade
5109speed for memory and install an UNCOMPRESSED image instead: this
5110needs more space in Flash, but boots much faster since it does not
5111need to be uncompressed:
5112
5113	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5114	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5115	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5116	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5117	> examples/uImage.TQM850L-uncompressed
5118	Image Name:   2.4.4 kernel for TQM850L
5119	Created:      Wed Jul 19 02:34:59 2000
5120	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5121	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5122	Load Address: 0x00000000
5123	Entry Point:  0x00000000
5124
5125
5126Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5127when your kernel is intended to use an initial ramdisk:
5128
5129	-> tools/mkimage -n 'Simple Ramdisk Image' \
5130	> -A ppc -O linux -T ramdisk -C gzip \
5131	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5132	Image Name:   Simple Ramdisk Image
5133	Created:      Wed Jan 12 14:01:50 2000
5134	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5135	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5136	Load Address: 0x00000000
5137	Entry Point:  0x00000000
5138
5139
5140Installing a Linux Image:
5141-------------------------
5142
5143To downloading a U-Boot image over the serial (console) interface,
5144you must convert the image to S-Record format:
5145
5146	objcopy -I binary -O srec examples/image examples/image.srec
5147
5148The 'objcopy' does not understand the information in the U-Boot
5149image header, so the resulting S-Record file will be relative to
5150address 0x00000000. To load it to a given address, you need to
5151specify the target address as 'offset' parameter with the 'loads'
5152command.
5153
5154Example: install the image to address 0x40100000 (which on the
5155TQM8xxL is in the first Flash bank):
5156
5157	=> erase 40100000 401FFFFF
5158
5159	.......... done
5160	Erased 8 sectors
5161
5162	=> loads 40100000
5163	## Ready for S-Record download ...
5164	~>examples/image.srec
5165	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5166	...
5167	15989 15990 15991 15992
5168	[file transfer complete]
5169	[connected]
5170	## Start Addr = 0x00000000
5171
5172
5173You can check the success of the download using the 'iminfo' command;
5174this includes a checksum verification so you can be sure no data
5175corruption happened:
5176
5177	=> imi 40100000
5178
5179	## Checking Image at 40100000 ...
5180	   Image Name:	 2.2.13 for initrd on TQM850L
5181	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5182	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5183	   Load Address: 00000000
5184	   Entry Point:	 0000000c
5185	   Verifying Checksum ... OK
5186
5187
5188Boot Linux:
5189-----------
5190
5191The "bootm" command is used to boot an application that is stored in
5192memory (RAM or Flash). In case of a Linux kernel image, the contents
5193of the "bootargs" environment variable is passed to the kernel as
5194parameters. You can check and modify this variable using the
5195"printenv" and "setenv" commands:
5196
5197
5198	=> printenv bootargs
5199	bootargs=root=/dev/ram
5200
5201	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5202
5203	=> printenv bootargs
5204	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5205
5206	=> bootm 40020000
5207	## Booting Linux kernel at 40020000 ...
5208	   Image Name:	 2.2.13 for NFS on TQM850L
5209	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5210	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5211	   Load Address: 00000000
5212	   Entry Point:	 0000000c
5213	   Verifying Checksum ... OK
5214	   Uncompressing Kernel Image ... OK
5215	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
5216	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5217	time_init: decrementer frequency = 187500000/60
5218	Calibrating delay loop... 49.77 BogoMIPS
5219	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5220	...
5221
5222If you want to boot a Linux kernel with initial RAM disk, you pass
5223the memory addresses of both the kernel and the initrd image (PPBCOOT
5224format!) to the "bootm" command:
5225
5226	=> imi 40100000 40200000
5227
5228	## Checking Image at 40100000 ...
5229	   Image Name:	 2.2.13 for initrd on TQM850L
5230	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5231	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5232	   Load Address: 00000000
5233	   Entry Point:	 0000000c
5234	   Verifying Checksum ... OK
5235
5236	## Checking Image at 40200000 ...
5237	   Image Name:	 Simple Ramdisk Image
5238	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5239	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5240	   Load Address: 00000000
5241	   Entry Point:	 00000000
5242	   Verifying Checksum ... OK
5243
5244	=> bootm 40100000 40200000
5245	## Booting Linux kernel at 40100000 ...
5246	   Image Name:	 2.2.13 for initrd on TQM850L
5247	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5248	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5249	   Load Address: 00000000
5250	   Entry Point:	 0000000c
5251	   Verifying Checksum ... OK
5252	   Uncompressing Kernel Image ... OK
5253	## Loading RAMDisk Image at 40200000 ...
5254	   Image Name:	 Simple Ramdisk Image
5255	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5256	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5257	   Load Address: 00000000
5258	   Entry Point:	 00000000
5259	   Verifying Checksum ... OK
5260	   Loading Ramdisk ... OK
5261	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
5262	Boot arguments: root=/dev/ram
5263	time_init: decrementer frequency = 187500000/60
5264	Calibrating delay loop... 49.77 BogoMIPS
5265	...
5266	RAMDISK: Compressed image found at block 0
5267	VFS: Mounted root (ext2 filesystem).
5268
5269	bash#
5270
5271Boot Linux and pass a flat device tree:
5272-----------
5273
5274First, U-Boot must be compiled with the appropriate defines. See the section
5275titled "Linux Kernel Interface" above for a more in depth explanation. The
5276following is an example of how to start a kernel and pass an updated
5277flat device tree:
5278
5279=> print oftaddr
5280oftaddr=0x300000
5281=> print oft
5282oft=oftrees/mpc8540ads.dtb
5283=> tftp $oftaddr $oft
5284Speed: 1000, full duplex
5285Using TSEC0 device
5286TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5287Filename 'oftrees/mpc8540ads.dtb'.
5288Load address: 0x300000
5289Loading: #
5290done
5291Bytes transferred = 4106 (100a hex)
5292=> tftp $loadaddr $bootfile
5293Speed: 1000, full duplex
5294Using TSEC0 device
5295TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5296Filename 'uImage'.
5297Load address: 0x200000
5298Loading:############
5299done
5300Bytes transferred = 1029407 (fb51f hex)
5301=> print loadaddr
5302loadaddr=200000
5303=> print oftaddr
5304oftaddr=0x300000
5305=> bootm $loadaddr - $oftaddr
5306## Booting image at 00200000 ...
5307   Image Name:	 Linux-2.6.17-dirty
5308   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5309   Data Size:	 1029343 Bytes = 1005.2 kB
5310   Load Address: 00000000
5311   Entry Point:	 00000000
5312   Verifying Checksum ... OK
5313   Uncompressing Kernel Image ... OK
5314Booting using flat device tree at 0x300000
5315Using MPC85xx ADS machine description
5316Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5317[snip]
5318
5319
5320More About U-Boot Image Types:
5321------------------------------
5322
5323U-Boot supports the following image types:
5324
5325   "Standalone Programs" are directly runnable in the environment
5326	provided by U-Boot; it is expected that (if they behave
5327	well) you can continue to work in U-Boot after return from
5328	the Standalone Program.
5329   "OS Kernel Images" are usually images of some Embedded OS which
5330	will take over control completely. Usually these programs
5331	will install their own set of exception handlers, device
5332	drivers, set up the MMU, etc. - this means, that you cannot
5333	expect to re-enter U-Boot except by resetting the CPU.
5334   "RAMDisk Images" are more or less just data blocks, and their
5335	parameters (address, size) are passed to an OS kernel that is
5336	being started.
5337   "Multi-File Images" contain several images, typically an OS
5338	(Linux) kernel image and one or more data images like
5339	RAMDisks. This construct is useful for instance when you want
5340	to boot over the network using BOOTP etc., where the boot
5341	server provides just a single image file, but you want to get
5342	for instance an OS kernel and a RAMDisk image.
5343
5344	"Multi-File Images" start with a list of image sizes, each
5345	image size (in bytes) specified by an "uint32_t" in network
5346	byte order. This list is terminated by an "(uint32_t)0".
5347	Immediately after the terminating 0 follow the images, one by
5348	one, all aligned on "uint32_t" boundaries (size rounded up to
5349	a multiple of 4 bytes).
5350
5351   "Firmware Images" are binary images containing firmware (like
5352	U-Boot or FPGA images) which usually will be programmed to
5353	flash memory.
5354
5355   "Script files" are command sequences that will be executed by
5356	U-Boot's command interpreter; this feature is especially
5357	useful when you configure U-Boot to use a real shell (hush)
5358	as command interpreter.
5359
5360Booting the Linux zImage:
5361-------------------------
5362
5363On some platforms, it's possible to boot Linux zImage. This is done
5364using the "bootz" command. The syntax of "bootz" command is the same
5365as the syntax of "bootm" command.
5366
5367Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5368kernel with raw initrd images. The syntax is slightly different, the
5369address of the initrd must be augmented by it's size, in the following
5370format: "<initrd addres>:<initrd size>".
5371
5372
5373Standalone HOWTO:
5374=================
5375
5376One of the features of U-Boot is that you can dynamically load and
5377run "standalone" applications, which can use some resources of
5378U-Boot like console I/O functions or interrupt services.
5379
5380Two simple examples are included with the sources:
5381
5382"Hello World" Demo:
5383-------------------
5384
5385'examples/hello_world.c' contains a small "Hello World" Demo
5386application; it is automatically compiled when you build U-Boot.
5387It's configured to run at address 0x00040004, so you can play with it
5388like that:
5389
5390	=> loads
5391	## Ready for S-Record download ...
5392	~>examples/hello_world.srec
5393	1 2 3 4 5 6 7 8 9 10 11 ...
5394	[file transfer complete]
5395	[connected]
5396	## Start Addr = 0x00040004
5397
5398	=> go 40004 Hello World! This is a test.
5399	## Starting application at 0x00040004 ...
5400	Hello World
5401	argc = 7
5402	argv[0] = "40004"
5403	argv[1] = "Hello"
5404	argv[2] = "World!"
5405	argv[3] = "This"
5406	argv[4] = "is"
5407	argv[5] = "a"
5408	argv[6] = "test."
5409	argv[7] = "<NULL>"
5410	Hit any key to exit ...
5411
5412	## Application terminated, rc = 0x0
5413
5414Another example, which demonstrates how to register a CPM interrupt
5415handler with the U-Boot code, can be found in 'examples/timer.c'.
5416Here, a CPM timer is set up to generate an interrupt every second.
5417The interrupt service routine is trivial, just printing a '.'
5418character, but this is just a demo program. The application can be
5419controlled by the following keys:
5420
5421	? - print current values og the CPM Timer registers
5422	b - enable interrupts and start timer
5423	e - stop timer and disable interrupts
5424	q - quit application
5425
5426	=> loads
5427	## Ready for S-Record download ...
5428	~>examples/timer.srec
5429	1 2 3 4 5 6 7 8 9 10 11 ...
5430	[file transfer complete]
5431	[connected]
5432	## Start Addr = 0x00040004
5433
5434	=> go 40004
5435	## Starting application at 0x00040004 ...
5436	TIMERS=0xfff00980
5437	Using timer 1
5438	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5439
5440Hit 'b':
5441	[q, b, e, ?] Set interval 1000000 us
5442	Enabling timer
5443Hit '?':
5444	[q, b, e, ?] ........
5445	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5446Hit '?':
5447	[q, b, e, ?] .
5448	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5449Hit '?':
5450	[q, b, e, ?] .
5451	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5452Hit '?':
5453	[q, b, e, ?] .
5454	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5455Hit 'e':
5456	[q, b, e, ?] ...Stopping timer
5457Hit 'q':
5458	[q, b, e, ?] ## Application terminated, rc = 0x0
5459
5460
5461Minicom warning:
5462================
5463
5464Over time, many people have reported problems when trying to use the
5465"minicom" terminal emulation program for serial download. I (wd)
5466consider minicom to be broken, and recommend not to use it. Under
5467Unix, I recommend to use C-Kermit for general purpose use (and
5468especially for kermit binary protocol download ("loadb" command), and
5469use "cu" for S-Record download ("loads" command).  See
5470http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5471for help with kermit.
5472
5473
5474Nevertheless, if you absolutely want to use it try adding this
5475configuration to your "File transfer protocols" section:
5476
5477	   Name	   Program			Name U/D FullScr IO-Red. Multi
5478	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5479	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5480
5481
5482NetBSD Notes:
5483=============
5484
5485Starting at version 0.9.2, U-Boot supports NetBSD both as host
5486(build U-Boot) and target system (boots NetBSD/mpc8xx).
5487
5488Building requires a cross environment; it is known to work on
5489NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5490need gmake since the Makefiles are not compatible with BSD make).
5491Note that the cross-powerpc package does not install include files;
5492attempting to build U-Boot will fail because <machine/ansi.h> is
5493missing.  This file has to be installed and patched manually:
5494
5495	# cd /usr/pkg/cross/powerpc-netbsd/include
5496	# mkdir powerpc
5497	# ln -s powerpc machine
5498	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5499	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5500
5501Native builds *don't* work due to incompatibilities between native
5502and U-Boot include files.
5503
5504Booting assumes that (the first part of) the image booted is a
5505stage-2 loader which in turn loads and then invokes the kernel
5506proper. Loader sources will eventually appear in the NetBSD source
5507tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5508meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5509
5510
5511Implementation Internals:
5512=========================
5513
5514The following is not intended to be a complete description of every
5515implementation detail. However, it should help to understand the
5516inner workings of U-Boot and make it easier to port it to custom
5517hardware.
5518
5519
5520Initial Stack, Global Data:
5521---------------------------
5522
5523The implementation of U-Boot is complicated by the fact that U-Boot
5524starts running out of ROM (flash memory), usually without access to
5525system RAM (because the memory controller is not initialized yet).
5526This means that we don't have writable Data or BSS segments, and BSS
5527is not initialized as zero. To be able to get a C environment working
5528at all, we have to allocate at least a minimal stack. Implementation
5529options for this are defined and restricted by the CPU used: Some CPU
5530models provide on-chip memory (like the IMMR area on MPC8xx and
5531MPC826x processors), on others (parts of) the data cache can be
5532locked as (mis-) used as memory, etc.
5533
5534	Chris Hallinan posted a good summary of these issues to the
5535	U-Boot mailing list:
5536
5537	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5538	From: "Chris Hallinan" <clh@net1plus.com>
5539	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5540	...
5541
5542	Correct me if I'm wrong, folks, but the way I understand it
5543	is this: Using DCACHE as initial RAM for Stack, etc, does not
5544	require any physical RAM backing up the cache. The cleverness
5545	is that the cache is being used as a temporary supply of
5546	necessary storage before the SDRAM controller is setup. It's
5547	beyond the scope of this list to explain the details, but you
5548	can see how this works by studying the cache architecture and
5549	operation in the architecture and processor-specific manuals.
5550
5551	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5552	is another option for the system designer to use as an
5553	initial stack/RAM area prior to SDRAM being available. Either
5554	option should work for you. Using CS 4 should be fine if your
5555	board designers haven't used it for something that would
5556	cause you grief during the initial boot! It is frequently not
5557	used.
5558
5559	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5560	with your processor/board/system design. The default value
5561	you will find in any recent u-boot distribution in
5562	walnut.h should work for you. I'd set it to a value larger
5563	than your SDRAM module. If you have a 64MB SDRAM module, set
5564	it above 400_0000. Just make sure your board has no resources
5565	that are supposed to respond to that address! That code in
5566	start.S has been around a while and should work as is when
5567	you get the config right.
5568
5569	-Chris Hallinan
5570	DS4.COM, Inc.
5571
5572It is essential to remember this, since it has some impact on the C
5573code for the initialization procedures:
5574
5575* Initialized global data (data segment) is read-only. Do not attempt
5576  to write it.
5577
5578* Do not use any uninitialized global data (or implicitely initialized
5579  as zero data - BSS segment) at all - this is undefined, initiali-
5580  zation is performed later (when relocating to RAM).
5581
5582* Stack space is very limited. Avoid big data buffers or things like
5583  that.
5584
5585Having only the stack as writable memory limits means we cannot use
5586normal global data to share information beween the code. But it
5587turned out that the implementation of U-Boot can be greatly
5588simplified by making a global data structure (gd_t) available to all
5589functions. We could pass a pointer to this data as argument to _all_
5590functions, but this would bloat the code. Instead we use a feature of
5591the GCC compiler (Global Register Variables) to share the data: we
5592place a pointer (gd) to the global data into a register which we
5593reserve for this purpose.
5594
5595When choosing a register for such a purpose we are restricted by the
5596relevant  (E)ABI  specifications for the current architecture, and by
5597GCC's implementation.
5598
5599For PowerPC, the following registers have specific use:
5600	R1:	stack pointer
5601	R2:	reserved for system use
5602	R3-R4:	parameter passing and return values
5603	R5-R10: parameter passing
5604	R13:	small data area pointer
5605	R30:	GOT pointer
5606	R31:	frame pointer
5607
5608	(U-Boot also uses R12 as internal GOT pointer. r12
5609	is a volatile register so r12 needs to be reset when
5610	going back and forth between asm and C)
5611
5612    ==> U-Boot will use R2 to hold a pointer to the global data
5613
5614    Note: on PPC, we could use a static initializer (since the
5615    address of the global data structure is known at compile time),
5616    but it turned out that reserving a register results in somewhat
5617    smaller code - although the code savings are not that big (on
5618    average for all boards 752 bytes for the whole U-Boot image,
5619    624 text + 127 data).
5620
5621On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5622	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5623
5624    ==> U-Boot will use P3 to hold a pointer to the global data
5625
5626On ARM, the following registers are used:
5627
5628	R0:	function argument word/integer result
5629	R1-R3:	function argument word
5630	R9:	platform specific
5631	R10:	stack limit (used only if stack checking is enabled)
5632	R11:	argument (frame) pointer
5633	R12:	temporary workspace
5634	R13:	stack pointer
5635	R14:	link register
5636	R15:	program counter
5637
5638    ==> U-Boot will use R9 to hold a pointer to the global data
5639
5640    Note: on ARM, only R_ARM_RELATIVE relocations are supported.
5641
5642On Nios II, the ABI is documented here:
5643	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5644
5645    ==> U-Boot will use gp to hold a pointer to the global data
5646
5647    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5648    to access small data sections, so gp is free.
5649
5650On NDS32, the following registers are used:
5651
5652	R0-R1:	argument/return
5653	R2-R5:	argument
5654	R15:	temporary register for assembler
5655	R16:	trampoline register
5656	R28:	frame pointer (FP)
5657	R29:	global pointer (GP)
5658	R30:	link register (LP)
5659	R31:	stack pointer (SP)
5660	PC:	program counter (PC)
5661
5662    ==> U-Boot will use R10 to hold a pointer to the global data
5663
5664NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5665or current versions of GCC may "optimize" the code too much.
5666
5667Memory Management:
5668------------------
5669
5670U-Boot runs in system state and uses physical addresses, i.e. the
5671MMU is not used either for address mapping nor for memory protection.
5672
5673The available memory is mapped to fixed addresses using the memory
5674controller. In this process, a contiguous block is formed for each
5675memory type (Flash, SDRAM, SRAM), even when it consists of several
5676physical memory banks.
5677
5678U-Boot is installed in the first 128 kB of the first Flash bank (on
5679TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5680booting and sizing and initializing DRAM, the code relocates itself
5681to the upper end of DRAM. Immediately below the U-Boot code some
5682memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5683configuration setting]. Below that, a structure with global Board
5684Info data is placed, followed by the stack (growing downward).
5685
5686Additionally, some exception handler code is copied to the low 8 kB
5687of DRAM (0x00000000 ... 0x00001FFF).
5688
5689So a typical memory configuration with 16 MB of DRAM could look like
5690this:
5691
5692	0x0000 0000	Exception Vector code
5693	      :
5694	0x0000 1FFF
5695	0x0000 2000	Free for Application Use
5696	      :
5697	      :
5698
5699	      :
5700	      :
5701	0x00FB FF20	Monitor Stack (Growing downward)
5702	0x00FB FFAC	Board Info Data and permanent copy of global data
5703	0x00FC 0000	Malloc Arena
5704	      :
5705	0x00FD FFFF
5706	0x00FE 0000	RAM Copy of Monitor Code
5707	...		eventually: LCD or video framebuffer
5708	...		eventually: pRAM (Protected RAM - unchanged by reset)
5709	0x00FF FFFF	[End of RAM]
5710
5711
5712System Initialization:
5713----------------------
5714
5715In the reset configuration, U-Boot starts at the reset entry point
5716(on most PowerPC systems at address 0x00000100). Because of the reset
5717configuration for CS0# this is a mirror of the onboard Flash memory.
5718To be able to re-map memory U-Boot then jumps to its link address.
5719To be able to implement the initialization code in C, a (small!)
5720initial stack is set up in the internal Dual Ported RAM (in case CPUs
5721which provide such a feature like MPC8xx or MPC8260), or in a locked
5722part of the data cache. After that, U-Boot initializes the CPU core,
5723the caches and the SIU.
5724
5725Next, all (potentially) available memory banks are mapped using a
5726preliminary mapping. For example, we put them on 512 MB boundaries
5727(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5728on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5729programmed for SDRAM access. Using the temporary configuration, a
5730simple memory test is run that determines the size of the SDRAM
5731banks.
5732
5733When there is more than one SDRAM bank, and the banks are of
5734different size, the largest is mapped first. For equal size, the first
5735bank (CS2#) is mapped first. The first mapping is always for address
57360x00000000, with any additional banks following immediately to create
5737contiguous memory starting from 0.
5738
5739Then, the monitor installs itself at the upper end of the SDRAM area
5740and allocates memory for use by malloc() and for the global Board
5741Info data; also, the exception vector code is copied to the low RAM
5742pages, and the final stack is set up.
5743
5744Only after this relocation will you have a "normal" C environment;
5745until that you are restricted in several ways, mostly because you are
5746running from ROM, and because the code will have to be relocated to a
5747new address in RAM.
5748
5749
5750U-Boot Porting Guide:
5751----------------------
5752
5753[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5754list, October 2002]
5755
5756
5757int main(int argc, char *argv[])
5758{
5759	sighandler_t no_more_time;
5760
5761	signal(SIGALRM, no_more_time);
5762	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5763
5764	if (available_money > available_manpower) {
5765		Pay consultant to port U-Boot;
5766		return 0;
5767	}
5768
5769	Download latest U-Boot source;
5770
5771	Subscribe to u-boot mailing list;
5772
5773	if (clueless)
5774		email("Hi, I am new to U-Boot, how do I get started?");
5775
5776	while (learning) {
5777		Read the README file in the top level directory;
5778		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5779		Read applicable doc/*.README;
5780		Read the source, Luke;
5781		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5782	}
5783
5784	if (available_money > toLocalCurrency ($2500))
5785		Buy a BDI3000;
5786	else
5787		Add a lot of aggravation and time;
5788
5789	if (a similar board exists) {	/* hopefully... */
5790		cp -a board/<similar> board/<myboard>
5791		cp include/configs/<similar>.h include/configs/<myboard>.h
5792	} else {
5793		Create your own board support subdirectory;
5794		Create your own board include/configs/<myboard>.h file;
5795	}
5796	Edit new board/<myboard> files
5797	Edit new include/configs/<myboard>.h
5798
5799	while (!accepted) {
5800		while (!running) {
5801			do {
5802				Add / modify source code;
5803			} until (compiles);
5804			Debug;
5805			if (clueless)
5806				email("Hi, I am having problems...");
5807		}
5808		Send patch file to the U-Boot email list;
5809		if (reasonable critiques)
5810			Incorporate improvements from email list code review;
5811		else
5812			Defend code as written;
5813	}
5814
5815	return 0;
5816}
5817
5818void no_more_time (int sig)
5819{
5820      hire_a_guru();
5821}
5822
5823
5824Coding Standards:
5825-----------------
5826
5827All contributions to U-Boot should conform to the Linux kernel
5828coding style; see the file "Documentation/CodingStyle" and the script
5829"scripts/Lindent" in your Linux kernel source directory.
5830
5831Source files originating from a different project (for example the
5832MTD subsystem) are generally exempt from these guidelines and are not
5833reformated to ease subsequent migration to newer versions of those
5834sources.
5835
5836Please note that U-Boot is implemented in C (and to some small parts in
5837Assembler); no C++ is used, so please do not use C++ style comments (//)
5838in your code.
5839
5840Please also stick to the following formatting rules:
5841- remove any trailing white space
5842- use TAB characters for indentation and vertical alignment, not spaces
5843- make sure NOT to use DOS '\r\n' line feeds
5844- do not add more than 2 consecutive empty lines to source files
5845- do not add trailing empty lines to source files
5846
5847Submissions which do not conform to the standards may be returned
5848with a request to reformat the changes.
5849
5850
5851Submitting Patches:
5852-------------------
5853
5854Since the number of patches for U-Boot is growing, we need to
5855establish some rules. Submissions which do not conform to these rules
5856may be rejected, even when they contain important and valuable stuff.
5857
5858Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5859
5860Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5861see http://lists.denx.de/mailman/listinfo/u-boot
5862
5863When you send a patch, please include the following information with
5864it:
5865
5866* For bug fixes: a description of the bug and how your patch fixes
5867  this bug. Please try to include a way of demonstrating that the
5868  patch actually fixes something.
5869
5870* For new features: a description of the feature and your
5871  implementation.
5872
5873* A CHANGELOG entry as plaintext (separate from the patch)
5874
5875* For major contributions, your entry to the CREDITS file
5876
5877* When you add support for a new board, don't forget to add a
5878  maintainer e-mail address to the boards.cfg file, too.
5879
5880* If your patch adds new configuration options, don't forget to
5881  document these in the README file.
5882
5883* The patch itself. If you are using git (which is *strongly*
5884  recommended) you can easily generate the patch using the
5885  "git format-patch". If you then use "git send-email" to send it to
5886  the U-Boot mailing list, you will avoid most of the common problems
5887  with some other mail clients.
5888
5889  If you cannot use git, use "diff -purN OLD NEW". If your version of
5890  diff does not support these options, then get the latest version of
5891  GNU diff.
5892
5893  The current directory when running this command shall be the parent
5894  directory of the U-Boot source tree (i. e. please make sure that
5895  your patch includes sufficient directory information for the
5896  affected files).
5897
5898  We prefer patches as plain text. MIME attachments are discouraged,
5899  and compressed attachments must not be used.
5900
5901* If one logical set of modifications affects or creates several
5902  files, all these changes shall be submitted in a SINGLE patch file.
5903
5904* Changesets that contain different, unrelated modifications shall be
5905  submitted as SEPARATE patches, one patch per changeset.
5906
5907
5908Notes:
5909
5910* Before sending the patch, run the MAKEALL script on your patched
5911  source tree and make sure that no errors or warnings are reported
5912  for any of the boards.
5913
5914* Keep your modifications to the necessary minimum: A patch
5915  containing several unrelated changes or arbitrary reformats will be
5916  returned with a request to re-formatting / split it.
5917
5918* If you modify existing code, make sure that your new code does not
5919  add to the memory footprint of the code ;-) Small is beautiful!
5920  When adding new features, these should compile conditionally only
5921  (using #ifdef), and the resulting code with the new feature
5922  disabled must not need more memory than the old code without your
5923  modification.
5924
5925* Remember that there is a size limit of 100 kB per message on the
5926  u-boot mailing list. Bigger patches will be moderated. If they are
5927  reasonable and not too big, they will be acknowledged. But patches
5928  bigger than the size limit should be avoided.
5929