xref: /rk3399_rockchip-uboot/README (revision 3f4978c713255c8406875fbdf23ffed1129bc44b)
1#
2# (C) Copyright 2000 - 2012
3# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
4#
5# See file CREDITS for list of people who contributed to this
6# project.
7#
8# This program is free software; you can redistribute it and/or
9# modify it under the terms of the GNU General Public License as
10# published by the Free Software Foundation; either version 2 of
11# the License, or (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the GNU General Public License
19# along with this program; if not, write to the Free Software
20# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21# MA 02111-1307 USA
22#
23
24Summary:
25========
26
27This directory contains the source code for U-Boot, a boot loader for
28Embedded boards based on PowerPC, ARM, MIPS and several other
29processors, which can be installed in a boot ROM and used to
30initialize and test the hardware or to download and run application
31code.
32
33The development of U-Boot is closely related to Linux: some parts of
34the source code originate in the Linux source tree, we have some
35header files in common, and special provision has been made to
36support booting of Linux images.
37
38Some attention has been paid to make this software easily
39configurable and extendable. For instance, all monitor commands are
40implemented with the same call interface, so that it's very easy to
41add new commands. Also, instead of permanently adding rarely used
42code (for instance hardware test utilities) to the monitor, you can
43load and run it dynamically.
44
45
46Status:
47=======
48
49In general, all boards for which a configuration option exists in the
50Makefile have been tested to some extent and can be considered
51"working". In fact, many of them are used in production systems.
52
53In case of problems see the CHANGELOG and CREDITS files to find out
54who contributed the specific port. The MAINTAINERS file lists board
55maintainers.
56
57Note: There is no CHANGELOG file in the actual U-Boot source tree;
58it can be created dynamically from the Git log using:
59
60	make CHANGELOG
61
62
63Where to get help:
64==================
65
66In case you have questions about, problems with or contributions for
67U-Boot you should send a message to the U-Boot mailing list at
68<u-boot@lists.denx.de>. There is also an archive of previous traffic
69on the mailing list - please search the archive before asking FAQ's.
70Please see http://lists.denx.de/pipermail/u-boot and
71http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
72
73
74Where to get source code:
75=========================
76
77The U-Boot source code is maintained in the git repository at
78git://www.denx.de/git/u-boot.git ; you can browse it online at
79http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
80
81The "snapshot" links on this page allow you to download tarballs of
82any version you might be interested in. Official releases are also
83available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
84directory.
85
86Pre-built (and tested) images are available from
87ftp://ftp.denx.de/pub/u-boot/images/
88
89
90Where we come from:
91===================
92
93- start from 8xxrom sources
94- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
95- clean up code
96- make it easier to add custom boards
97- make it possible to add other [PowerPC] CPUs
98- extend functions, especially:
99  * Provide extended interface to Linux boot loader
100  * S-Record download
101  * network boot
102  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
103- create ARMBoot project (http://sourceforge.net/projects/armboot)
104- add other CPU families (starting with ARM)
105- create U-Boot project (http://sourceforge.net/projects/u-boot)
106- current project page: see http://www.denx.de/wiki/U-Boot
107
108
109Names and Spelling:
110===================
111
112The "official" name of this project is "Das U-Boot". The spelling
113"U-Boot" shall be used in all written text (documentation, comments
114in source files etc.). Example:
115
116	This is the README file for the U-Boot project.
117
118File names etc. shall be based on the string "u-boot". Examples:
119
120	include/asm-ppc/u-boot.h
121
122	#include <asm/u-boot.h>
123
124Variable names, preprocessor constants etc. shall be either based on
125the string "u_boot" or on "U_BOOT". Example:
126
127	U_BOOT_VERSION		u_boot_logo
128	IH_OS_U_BOOT		u_boot_hush_start
129
130
131Versioning:
132===========
133
134Starting with the release in October 2008, the names of the releases
135were changed from numerical release numbers without deeper meaning
136into a time stamp based numbering. Regular releases are identified by
137names consisting of the calendar year and month of the release date.
138Additional fields (if present) indicate release candidates or bug fix
139releases in "stable" maintenance trees.
140
141Examples:
142	U-Boot v2009.11	    - Release November 2009
143	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
144	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
145
146
147Directory Hierarchy:
148====================
149
150/arch			Architecture specific files
151  /arm			Files generic to ARM architecture
152    /cpu		CPU specific files
153      /arm720t		Files specific to ARM 720 CPUs
154      /arm920t		Files specific to ARM 920 CPUs
155	/at91		Files specific to Atmel AT91RM9200 CPU
156	/imx		Files specific to Freescale MC9328 i.MX CPUs
157	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
158      /arm925t		Files specific to ARM 925 CPUs
159      /arm926ejs	Files specific to ARM 926 CPUs
160      /arm1136		Files specific to ARM 1136 CPUs
161      /ixp		Files specific to Intel XScale IXP CPUs
162      /pxa		Files specific to Intel XScale PXA CPUs
163      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
164      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
165    /lib		Architecture specific library files
166  /avr32		Files generic to AVR32 architecture
167    /cpu		CPU specific files
168    /lib		Architecture specific library files
169  /blackfin		Files generic to Analog Devices Blackfin architecture
170    /cpu		CPU specific files
171    /lib		Architecture specific library files
172  /x86			Files generic to x86 architecture
173    /cpu		CPU specific files
174    /lib		Architecture specific library files
175  /m68k			Files generic to m68k architecture
176    /cpu		CPU specific files
177      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
178      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
179      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
180      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
181      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
182    /lib		Architecture specific library files
183  /microblaze		Files generic to microblaze architecture
184    /cpu		CPU specific files
185    /lib		Architecture specific library files
186  /mips			Files generic to MIPS architecture
187    /cpu		CPU specific files
188      /mips32		Files specific to MIPS32 CPUs
189      /xburst		Files specific to Ingenic XBurst CPUs
190    /lib		Architecture specific library files
191  /nds32		Files generic to NDS32 architecture
192    /cpu		CPU specific files
193      /n1213		Files specific to Andes Technology N1213 CPUs
194    /lib		Architecture specific library files
195  /nios2		Files generic to Altera NIOS2 architecture
196    /cpu		CPU specific files
197    /lib		Architecture specific library files
198  /powerpc		Files generic to PowerPC architecture
199    /cpu		CPU specific files
200      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
201      /mpc5xx		Files specific to Freescale MPC5xx CPUs
202      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
203      /mpc8xx		Files specific to Freescale MPC8xx CPUs
204      /mpc824x		Files specific to Freescale MPC824x CPUs
205      /mpc8260		Files specific to Freescale MPC8260 CPUs
206      /mpc85xx		Files specific to Freescale MPC85xx CPUs
207      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
208    /lib		Architecture specific library files
209  /sh			Files generic to SH architecture
210    /cpu		CPU specific files
211      /sh2		Files specific to sh2 CPUs
212      /sh3		Files specific to sh3 CPUs
213      /sh4		Files specific to sh4 CPUs
214    /lib		Architecture specific library files
215  /sparc		Files generic to SPARC architecture
216    /cpu		CPU specific files
217      /leon2		Files specific to Gaisler LEON2 SPARC CPU
218      /leon3		Files specific to Gaisler LEON3 SPARC CPU
219    /lib		Architecture specific library files
220/api			Machine/arch independent API for external apps
221/board			Board dependent files
222/common			Misc architecture independent functions
223/disk			Code for disk drive partition handling
224/doc			Documentation (don't expect too much)
225/drivers		Commonly used device drivers
226/examples		Example code for standalone applications, etc.
227/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
228/include		Header Files
229/lib			Files generic to all architectures
230  /libfdt		Library files to support flattened device trees
231  /lzma			Library files to support LZMA decompression
232  /lzo			Library files to support LZO decompression
233/net			Networking code
234/post			Power On Self Test
235/rtc			Real Time Clock drivers
236/tools			Tools to build S-Record or U-Boot images, etc.
237
238Software Configuration:
239=======================
240
241Configuration is usually done using C preprocessor defines; the
242rationale behind that is to avoid dead code whenever possible.
243
244There are two classes of configuration variables:
245
246* Configuration _OPTIONS_:
247  These are selectable by the user and have names beginning with
248  "CONFIG_".
249
250* Configuration _SETTINGS_:
251  These depend on the hardware etc. and should not be meddled with if
252  you don't know what you're doing; they have names beginning with
253  "CONFIG_SYS_".
254
255Later we will add a configuration tool - probably similar to or even
256identical to what's used for the Linux kernel. Right now, we have to
257do the configuration by hand, which means creating some symbolic
258links and editing some configuration files. We use the TQM8xxL boards
259as an example here.
260
261
262Selection of Processor Architecture and Board Type:
263---------------------------------------------------
264
265For all supported boards there are ready-to-use default
266configurations available; just type "make <board_name>_config".
267
268Example: For a TQM823L module type:
269
270	cd u-boot
271	make TQM823L_config
272
273For the Cogent platform, you need to specify the CPU type as well;
274e.g. "make cogent_mpc8xx_config". And also configure the cogent
275directory according to the instructions in cogent/README.
276
277
278Configuration Options:
279----------------------
280
281Configuration depends on the combination of board and CPU type; all
282such information is kept in a configuration file
283"include/configs/<board_name>.h".
284
285Example: For a TQM823L module, all configuration settings are in
286"include/configs/TQM823L.h".
287
288
289Many of the options are named exactly as the corresponding Linux
290kernel configuration options. The intention is to make it easier to
291build a config tool - later.
292
293
294The following options need to be configured:
295
296- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
297
298- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
299
300- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
301		Define exactly one, e.g. CONFIG_ATSTK1002
302
303- CPU Module Type: (if CONFIG_COGENT is defined)
304		Define exactly one of
305		CONFIG_CMA286_60_OLD
306--- FIXME --- not tested yet:
307		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
308		CONFIG_CMA287_23, CONFIG_CMA287_50
309
310- Motherboard Type: (if CONFIG_COGENT is defined)
311		Define exactly one of
312		CONFIG_CMA101, CONFIG_CMA102
313
314- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
315		Define one or more of
316		CONFIG_CMA302
317
318- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
319		Define one or more of
320		CONFIG_LCD_HEARTBEAT	- update a character position on
321					  the LCD display every second with
322					  a "rotator" |\-/|\-/
323
324- Board flavour: (if CONFIG_MPC8260ADS is defined)
325		CONFIG_ADSTYPE
326		Possible values are:
327			CONFIG_SYS_8260ADS	- original MPC8260ADS
328			CONFIG_SYS_8266ADS	- MPC8266ADS
329			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
330			CONFIG_SYS_8272ADS	- MPC8272ADS
331
332- Marvell Family Member
333		CONFIG_SYS_MVFS		- define it if you want to enable
334					  multiple fs option at one time
335					  for marvell soc family
336
337- MPC824X Family Member (if CONFIG_MPC824X is defined)
338		Define exactly one of
339		CONFIG_MPC8240, CONFIG_MPC8245
340
341- 8xx CPU Options: (if using an MPC8xx CPU)
342		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
343					  get_gclk_freq() cannot work
344					  e.g. if there is no 32KHz
345					  reference PIT/RTC clock
346		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
347					  or XTAL/EXTAL)
348
349- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
350		CONFIG_SYS_8xx_CPUCLK_MIN
351		CONFIG_SYS_8xx_CPUCLK_MAX
352		CONFIG_8xx_CPUCLK_DEFAULT
353			See doc/README.MPC866
354
355		CONFIG_SYS_MEASURE_CPUCLK
356
357		Define this to measure the actual CPU clock instead
358		of relying on the correctness of the configured
359		values. Mostly useful for board bringup to make sure
360		the PLL is locked at the intended frequency. Note
361		that this requires a (stable) reference clock (32 kHz
362		RTC clock or CONFIG_SYS_8XX_XIN)
363
364		CONFIG_SYS_DELAYED_ICACHE
365
366		Define this option if you want to enable the
367		ICache only when Code runs from RAM.
368
369- 85xx CPU Options:
370		CONFIG_SYS_PPC64
371
372		Specifies that the core is a 64-bit PowerPC implementation (implements
373		the "64" category of the Power ISA). This is necessary for ePAPR
374		compliance, among other possible reasons.
375
376		CONFIG_SYS_FSL_TBCLK_DIV
377
378		Defines the core time base clock divider ratio compared to the
379		system clock.  On most PQ3 devices this is 8, on newer QorIQ
380		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
381
382		CONFIG_SYS_FSL_PCIE_COMPAT
383
384		Defines the string to utilize when trying to match PCIe device
385		tree nodes for the given platform.
386
387		CONFIG_SYS_PPC_E500_DEBUG_TLB
388
389		Enables a temporary TLB entry to be used during boot to work
390		around limitations in e500v1 and e500v2 external debugger
391		support. This reduces the portions of the boot code where
392		breakpoints and single stepping do not work.  The value of this
393		symbol should be set to the TLB1 entry to be used for this
394		purpose.
395
396		CONFIG_SYS_FSL_ERRATUM_A004510
397
398		Enables a workaround for erratum A004510.  If set,
399		then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
400		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
401
402		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
403		CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
404
405		Defines one or two SoC revisions (low 8 bits of SVR)
406		for which the A004510 workaround should be applied.
407
408		The rest of SVR is either not relevant to the decision
409		of whether the erratum is present (e.g. p2040 versus
410		p2041) or is implied by the build target, which controls
411		whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
412
413		See Freescale App Note 4493 for more information about
414		this erratum.
415
416		CONFIG_A003399_NOR_WORKAROUND
417		Enables a workaround for IFC erratum A003399. It is only
418		requred during NOR boot.
419
420		CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
421
422		This is the value to write into CCSR offset 0x18600
423		according to the A004510 workaround.
424
425		CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
426		This value denotes start offset of M2 memory
427		which is directly connected to the DSP core.
428
429		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
430		This value denotes start offset of DSP CCSR space.
431
432- Generic CPU options:
433		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
434
435		Defines the endianess of the CPU. Implementation of those
436		values is arch specific.
437
438- Intel Monahans options:
439		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
440
441		Defines the Monahans run mode to oscillator
442		ratio. Valid values are 8, 16, 24, 31. The core
443		frequency is this value multiplied by 13 MHz.
444
445		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
446
447		Defines the Monahans turbo mode to oscillator
448		ratio. Valid values are 1 (default if undefined) and
449		2. The core frequency as calculated above is multiplied
450		by this value.
451
452- MIPS CPU options:
453		CONFIG_SYS_INIT_SP_OFFSET
454
455		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
456		pointer. This is needed for the temporary stack before
457		relocation.
458
459		CONFIG_SYS_MIPS_CACHE_MODE
460
461		Cache operation mode for the MIPS CPU.
462		See also arch/mips/include/asm/mipsregs.h.
463		Possible values are:
464			CONF_CM_CACHABLE_NO_WA
465			CONF_CM_CACHABLE_WA
466			CONF_CM_UNCACHED
467			CONF_CM_CACHABLE_NONCOHERENT
468			CONF_CM_CACHABLE_CE
469			CONF_CM_CACHABLE_COW
470			CONF_CM_CACHABLE_CUW
471			CONF_CM_CACHABLE_ACCELERATED
472
473		CONFIG_SYS_XWAY_EBU_BOOTCFG
474
475		Special option for Lantiq XWAY SoCs for booting from NOR flash.
476		See also arch/mips/cpu/mips32/start.S.
477
478		CONFIG_XWAY_SWAP_BYTES
479
480		Enable compilation of tools/xway-swap-bytes needed for Lantiq
481		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
482		be swapped if a flash programmer is used.
483
484- ARM options:
485		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
486
487		Select high exception vectors of the ARM core, e.g., do not
488		clear the V bit of the c1 register of CP15.
489
490		CONFIG_SYS_THUMB_BUILD
491
492		Use this flag to build U-Boot using the Thumb instruction
493		set for ARM architectures. Thumb instruction set provides
494		better code density. For ARM architectures that support
495		Thumb2 this flag will result in Thumb2 code generated by
496		GCC.
497
498		CONFIG_ARM_ERRATA_716044
499		CONFIG_ARM_ERRATA_742230
500		CONFIG_ARM_ERRATA_743622
501		CONFIG_ARM_ERRATA_751472
502
503		If set, the workarounds for these ARM errata are applied early
504		during U-Boot startup. Note that these options force the
505		workarounds to be applied; no CPU-type/version detection
506		exists, unlike the similar options in the Linux kernel. Do not
507		set these options unless they apply!
508
509- CPU timer options:
510		CONFIG_SYS_HZ
511
512		The frequency of the timer returned by get_timer().
513		get_timer() must operate in milliseconds and this CONFIG
514		option must be set to 1000.
515
516- Linux Kernel Interface:
517		CONFIG_CLOCKS_IN_MHZ
518
519		U-Boot stores all clock information in Hz
520		internally. For binary compatibility with older Linux
521		kernels (which expect the clocks passed in the
522		bd_info data to be in MHz) the environment variable
523		"clocks_in_mhz" can be defined so that U-Boot
524		converts clock data to MHZ before passing it to the
525		Linux kernel.
526		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
527		"clocks_in_mhz=1" is automatically included in the
528		default environment.
529
530		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
531
532		When transferring memsize parameter to linux, some versions
533		expect it to be in bytes, others in MB.
534		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
535
536		CONFIG_OF_LIBFDT
537
538		New kernel versions are expecting firmware settings to be
539		passed using flattened device trees (based on open firmware
540		concepts).
541
542		CONFIG_OF_LIBFDT
543		 * New libfdt-based support
544		 * Adds the "fdt" command
545		 * The bootm command automatically updates the fdt
546
547		OF_CPU - The proper name of the cpus node (only required for
548			MPC512X and MPC5xxx based boards).
549		OF_SOC - The proper name of the soc node (only required for
550			MPC512X and MPC5xxx based boards).
551		OF_TBCLK - The timebase frequency.
552		OF_STDOUT_PATH - The path to the console device
553
554		boards with QUICC Engines require OF_QE to set UCC MAC
555		addresses
556
557		CONFIG_OF_BOARD_SETUP
558
559		Board code has addition modification that it wants to make
560		to the flat device tree before handing it off to the kernel
561
562		CONFIG_OF_BOOT_CPU
563
564		This define fills in the correct boot CPU in the boot
565		param header, the default value is zero if undefined.
566
567		CONFIG_OF_IDE_FIXUP
568
569		U-Boot can detect if an IDE device is present or not.
570		If not, and this new config option is activated, U-Boot
571		removes the ATA node from the DTS before booting Linux,
572		so the Linux IDE driver does not probe the device and
573		crash. This is needed for buggy hardware (uc101) where
574		no pull down resistor is connected to the signal IDE5V_DD7.
575
576		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
577
578		This setting is mandatory for all boards that have only one
579		machine type and must be used to specify the machine type
580		number as it appears in the ARM machine registry
581		(see http://www.arm.linux.org.uk/developer/machines/).
582		Only boards that have multiple machine types supported
583		in a single configuration file and the machine type is
584		runtime discoverable, do not have to use this setting.
585
586- vxWorks boot parameters:
587
588		bootvx constructs a valid bootline using the following
589		environments variables: bootfile, ipaddr, serverip, hostname.
590		It loads the vxWorks image pointed bootfile.
591
592		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
593		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
594		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
595		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
596
597		CONFIG_SYS_VXWORKS_ADD_PARAMS
598
599		Add it at the end of the bootline. E.g "u=username pw=secret"
600
601		Note: If a "bootargs" environment is defined, it will overwride
602		the defaults discussed just above.
603
604- Cache Configuration:
605		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
606		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
607		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
608
609- Cache Configuration for ARM:
610		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
611				      controller
612		CONFIG_SYS_PL310_BASE - Physical base address of PL310
613					controller register space
614
615- Serial Ports:
616		CONFIG_PL010_SERIAL
617
618		Define this if you want support for Amba PrimeCell PL010 UARTs.
619
620		CONFIG_PL011_SERIAL
621
622		Define this if you want support for Amba PrimeCell PL011 UARTs.
623
624		CONFIG_PL011_CLOCK
625
626		If you have Amba PrimeCell PL011 UARTs, set this variable to
627		the clock speed of the UARTs.
628
629		CONFIG_PL01x_PORTS
630
631		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
632		define this to a list of base addresses for each (supported)
633		port. See e.g. include/configs/versatile.h
634
635		CONFIG_PL011_SERIAL_RLCR
636
637		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
638		have separate receive and transmit line control registers.  Set
639		this variable to initialize the extra register.
640
641		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
642
643		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
644		boot loader that has already initialized the UART.  Define this
645		variable to flush the UART at init time.
646
647
648- Console Interface:
649		Depending on board, define exactly one serial port
650		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
651		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
652		console by defining CONFIG_8xx_CONS_NONE
653
654		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
655		port routines must be defined elsewhere
656		(i.e. serial_init(), serial_getc(), ...)
657
658		CONFIG_CFB_CONSOLE
659		Enables console device for a color framebuffer. Needs following
660		defines (cf. smiLynxEM, i8042)
661			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
662						(default big endian)
663			VIDEO_HW_RECTFILL	graphic chip supports
664						rectangle fill
665						(cf. smiLynxEM)
666			VIDEO_HW_BITBLT		graphic chip supports
667						bit-blit (cf. smiLynxEM)
668			VIDEO_VISIBLE_COLS	visible pixel columns
669						(cols=pitch)
670			VIDEO_VISIBLE_ROWS	visible pixel rows
671			VIDEO_PIXEL_SIZE	bytes per pixel
672			VIDEO_DATA_FORMAT	graphic data format
673						(0-5, cf. cfb_console.c)
674			VIDEO_FB_ADRS		framebuffer address
675			VIDEO_KBD_INIT_FCT	keyboard int fct
676						(i.e. i8042_kbd_init())
677			VIDEO_TSTC_FCT		test char fct
678						(i.e. i8042_tstc)
679			VIDEO_GETC_FCT		get char fct
680						(i.e. i8042_getc)
681			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
682						(requires blink timer
683						cf. i8042.c)
684			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
685			CONFIG_CONSOLE_TIME	display time/date info in
686						upper right corner
687						(requires CONFIG_CMD_DATE)
688			CONFIG_VIDEO_LOGO	display Linux logo in
689						upper left corner
690			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
691						linux_logo.h for logo.
692						Requires CONFIG_VIDEO_LOGO
693			CONFIG_CONSOLE_EXTRA_INFO
694						additional board info beside
695						the logo
696
697		When CONFIG_CFB_CONSOLE_ANSI is defined, console will support
698		a limited number of ANSI escape sequences (cursor control,
699		erase functions and limited graphics rendition control).
700
701		When CONFIG_CFB_CONSOLE is defined, video console is
702		default i/o. Serial console can be forced with
703		environment 'console=serial'.
704
705		When CONFIG_SILENT_CONSOLE is defined, all console
706		messages (by U-Boot and Linux!) can be silenced with
707		the "silent" environment variable. See
708		doc/README.silent for more information.
709
710- Console Baudrate:
711		CONFIG_BAUDRATE - in bps
712		Select one of the baudrates listed in
713		CONFIG_SYS_BAUDRATE_TABLE, see below.
714		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
715
716- Console Rx buffer length
717		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
718		the maximum receive buffer length for the SMC.
719		This option is actual only for 82xx and 8xx possible.
720		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
721		must be defined, to setup the maximum idle timeout for
722		the SMC.
723
724- Pre-Console Buffer:
725		Prior to the console being initialised (i.e. serial UART
726		initialised etc) all console output is silently discarded.
727		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
728		buffer any console messages prior to the console being
729		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
730		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
731		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
732		bytes are output before the console is initialised, the
733		earlier bytes are discarded.
734
735		'Sane' compilers will generate smaller code if
736		CONFIG_PRE_CON_BUF_SZ is a power of 2
737
738- Safe printf() functions
739		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
740		the printf() functions. These are defined in
741		include/vsprintf.h and include snprintf(), vsnprintf() and
742		so on. Code size increase is approximately 300-500 bytes.
743		If this option is not given then these functions will
744		silently discard their buffer size argument - this means
745		you are not getting any overflow checking in this case.
746
747- Boot Delay:	CONFIG_BOOTDELAY - in seconds
748		Delay before automatically booting the default image;
749		set to -1 to disable autoboot.
750		set to -2 to autoboot with no delay and not check for abort
751		(even when CONFIG_ZERO_BOOTDELAY_CHECK is defined).
752
753		See doc/README.autoboot for these options that
754		work with CONFIG_BOOTDELAY. None are required.
755		CONFIG_BOOT_RETRY_TIME
756		CONFIG_BOOT_RETRY_MIN
757		CONFIG_AUTOBOOT_KEYED
758		CONFIG_AUTOBOOT_PROMPT
759		CONFIG_AUTOBOOT_DELAY_STR
760		CONFIG_AUTOBOOT_STOP_STR
761		CONFIG_AUTOBOOT_DELAY_STR2
762		CONFIG_AUTOBOOT_STOP_STR2
763		CONFIG_ZERO_BOOTDELAY_CHECK
764		CONFIG_RESET_TO_RETRY
765
766- Autoboot Command:
767		CONFIG_BOOTCOMMAND
768		Only needed when CONFIG_BOOTDELAY is enabled;
769		define a command string that is automatically executed
770		when no character is read on the console interface
771		within "Boot Delay" after reset.
772
773		CONFIG_BOOTARGS
774		This can be used to pass arguments to the bootm
775		command. The value of CONFIG_BOOTARGS goes into the
776		environment value "bootargs".
777
778		CONFIG_RAMBOOT and CONFIG_NFSBOOT
779		The value of these goes into the environment as
780		"ramboot" and "nfsboot" respectively, and can be used
781		as a convenience, when switching between booting from
782		RAM and NFS.
783
784- Pre-Boot Commands:
785		CONFIG_PREBOOT
786
787		When this option is #defined, the existence of the
788		environment variable "preboot" will be checked
789		immediately before starting the CONFIG_BOOTDELAY
790		countdown and/or running the auto-boot command resp.
791		entering interactive mode.
792
793		This feature is especially useful when "preboot" is
794		automatically generated or modified. For an example
795		see the LWMON board specific code: here "preboot" is
796		modified when the user holds down a certain
797		combination of keys on the (special) keyboard when
798		booting the systems
799
800- Serial Download Echo Mode:
801		CONFIG_LOADS_ECHO
802		If defined to 1, all characters received during a
803		serial download (using the "loads" command) are
804		echoed back. This might be needed by some terminal
805		emulations (like "cu"), but may as well just take
806		time on others. This setting #define's the initial
807		value of the "loads_echo" environment variable.
808
809- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
810		CONFIG_KGDB_BAUDRATE
811		Select one of the baudrates listed in
812		CONFIG_SYS_BAUDRATE_TABLE, see below.
813
814- Monitor Functions:
815		Monitor commands can be included or excluded
816		from the build by using the #include files
817		<config_cmd_all.h> and #undef'ing unwanted
818		commands, or using <config_cmd_default.h>
819		and augmenting with additional #define's
820		for wanted commands.
821
822		The default command configuration includes all commands
823		except those marked below with a "*".
824
825		CONFIG_CMD_ASKENV	* ask for env variable
826		CONFIG_CMD_BDI		  bdinfo
827		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
828		CONFIG_CMD_BMP		* BMP support
829		CONFIG_CMD_BSP		* Board specific commands
830		CONFIG_CMD_BOOTD	  bootd
831		CONFIG_CMD_CACHE	* icache, dcache
832		CONFIG_CMD_CONSOLE	  coninfo
833		CONFIG_CMD_CRC32	* crc32
834		CONFIG_CMD_DATE		* support for RTC, date/time...
835		CONFIG_CMD_DHCP		* DHCP support
836		CONFIG_CMD_DIAG		* Diagnostics
837		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
838		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
839		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
840		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
841		CONFIG_CMD_DTT		* Digital Therm and Thermostat
842		CONFIG_CMD_ECHO		  echo arguments
843		CONFIG_CMD_EDITENV	  edit env variable
844		CONFIG_CMD_EEPROM	* EEPROM read/write support
845		CONFIG_CMD_ELF		* bootelf, bootvx
846		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
847		CONFIG_CMD_ENV_FLAGS	* display details about env flags
848		CONFIG_CMD_EXPORTENV	* export the environment
849		CONFIG_CMD_EXT2		* ext2 command support
850		CONFIG_CMD_EXT4		* ext4 command support
851		CONFIG_CMD_SAVEENV	  saveenv
852		CONFIG_CMD_FDC		* Floppy Disk Support
853		CONFIG_CMD_FAT		* FAT command support
854		CONFIG_CMD_FDOS		* Dos diskette Support
855		CONFIG_CMD_FLASH	  flinfo, erase, protect
856		CONFIG_CMD_FPGA		  FPGA device initialization support
857		CONFIG_CMD_FUSE		* Device fuse support
858		CONFIG_CMD_GETTIME	* Get time since boot
859		CONFIG_CMD_GO		* the 'go' command (exec code)
860		CONFIG_CMD_GREPENV	* search environment
861		CONFIG_CMD_HASH		* calculate hash / digest
862		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
863		CONFIG_CMD_I2C		* I2C serial bus support
864		CONFIG_CMD_IDE		* IDE harddisk support
865		CONFIG_CMD_IMI		  iminfo
866		CONFIG_CMD_IMLS		  List all images found in NOR flash
867		CONFIG_CMD_IMLS_NAND	* List all images found in NAND flash
868		CONFIG_CMD_IMMAP	* IMMR dump support
869		CONFIG_CMD_IMPORTENV	* import an environment
870		CONFIG_CMD_INI		* import data from an ini file into the env
871		CONFIG_CMD_IRQ		* irqinfo
872		CONFIG_CMD_ITEST	  Integer/string test of 2 values
873		CONFIG_CMD_JFFS2	* JFFS2 Support
874		CONFIG_CMD_KGDB		* kgdb
875		CONFIG_CMD_LDRINFO	* ldrinfo (display Blackfin loader)
876		CONFIG_CMD_LINK_LOCAL	* link-local IP address auto-configuration
877					  (169.254.*.*)
878		CONFIG_CMD_LOADB	  loadb
879		CONFIG_CMD_LOADS	  loads
880		CONFIG_CMD_MD5SUM	* print md5 message digest
881					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
882		CONFIG_CMD_MEMINFO	* Display detailed memory information
883		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
884					  loop, loopw
885		CONFIG_CMD_MEMTEST	* mtest
886		CONFIG_CMD_MISC		  Misc functions like sleep etc
887		CONFIG_CMD_MMC		* MMC memory mapped support
888		CONFIG_CMD_MII		* MII utility commands
889		CONFIG_CMD_MTDPARTS	* MTD partition support
890		CONFIG_CMD_NAND		* NAND support
891		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
892		CONFIG_CMD_NFS		  NFS support
893		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
894		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
895		CONFIG_CMD_PCI		* pciinfo
896		CONFIG_CMD_PCMCIA		* PCMCIA support
897		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
898					  host
899		CONFIG_CMD_PORTIO	* Port I/O
900		CONFIG_CMD_READ		* Read raw data from partition
901		CONFIG_CMD_REGINFO	* Register dump
902		CONFIG_CMD_RUN		  run command in env variable
903		CONFIG_CMD_SANDBOX	* sb command to access sandbox features
904		CONFIG_CMD_SAVES	* save S record dump
905		CONFIG_CMD_SCSI		* SCSI Support
906		CONFIG_CMD_SDRAM	* print SDRAM configuration information
907					  (requires CONFIG_CMD_I2C)
908		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
909					  (4xx only)
910		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
911		CONFIG_CMD_SHA1SUM	* print sha1 memory digest
912					  (requires CONFIG_CMD_MEMORY)
913		CONFIG_CMD_SOFTSWITCH	* Soft switch setting command for BF60x
914		CONFIG_CMD_SOURCE	  "source" command Support
915		CONFIG_CMD_SPI		* SPI serial bus support
916		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
917		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
918		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
919		CONFIG_CMD_TIMER	* access to the system tick timer
920		CONFIG_CMD_USB		* USB support
921		CONFIG_CMD_CDP		* Cisco Discover Protocol support
922		CONFIG_CMD_MFSL		* Microblaze FSL support
923		CONFIG_CMD_XIMG		  Load part of Multi Image
924
925
926		EXAMPLE: If you want all functions except of network
927		support you can write:
928
929		#include "config_cmd_all.h"
930		#undef CONFIG_CMD_NET
931
932	Other Commands:
933		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
934
935	Note:	Don't enable the "icache" and "dcache" commands
936		(configuration option CONFIG_CMD_CACHE) unless you know
937		what you (and your U-Boot users) are doing. Data
938		cache cannot be enabled on systems like the 8xx or
939		8260 (where accesses to the IMMR region must be
940		uncached), and it cannot be disabled on all other
941		systems where we (mis-) use the data cache to hold an
942		initial stack and some data.
943
944
945		XXX - this list needs to get updated!
946
947- Regular expression support:
948		CONFIG_REGEX
949                If this variable is defined, U-Boot is linked against
950                the SLRE (Super Light Regular Expression) library,
951                which adds regex support to some commands, as for
952                example "env grep" and "setexpr".
953
954- Device tree:
955		CONFIG_OF_CONTROL
956		If this variable is defined, U-Boot will use a device tree
957		to configure its devices, instead of relying on statically
958		compiled #defines in the board file. This option is
959		experimental and only available on a few boards. The device
960		tree is available in the global data as gd->fdt_blob.
961
962		U-Boot needs to get its device tree from somewhere. This can
963		be done using one of the two options below:
964
965		CONFIG_OF_EMBED
966		If this variable is defined, U-Boot will embed a device tree
967		binary in its image. This device tree file should be in the
968		board directory and called <soc>-<board>.dts. The binary file
969		is then picked up in board_init_f() and made available through
970		the global data structure as gd->blob.
971
972		CONFIG_OF_SEPARATE
973		If this variable is defined, U-Boot will build a device tree
974		binary. It will be called u-boot.dtb. Architecture-specific
975		code will locate it at run-time. Generally this works by:
976
977			cat u-boot.bin u-boot.dtb >image.bin
978
979		and in fact, U-Boot does this for you, creating a file called
980		u-boot-dtb.bin which is useful in the common case. You can
981		still use the individual files if you need something more
982		exotic.
983
984- Watchdog:
985		CONFIG_WATCHDOG
986		If this variable is defined, it enables watchdog
987		support for the SoC. There must be support in the SoC
988		specific code for a watchdog. For the 8xx and 8260
989		CPUs, the SIU Watchdog feature is enabled in the SYPCR
990		register.  When supported for a specific SoC is
991		available, then no further board specific code should
992		be needed to use it.
993
994		CONFIG_HW_WATCHDOG
995		When using a watchdog circuitry external to the used
996		SoC, then define this variable and provide board
997		specific code for the "hw_watchdog_reset" function.
998
999- U-Boot Version:
1000		CONFIG_VERSION_VARIABLE
1001		If this variable is defined, an environment variable
1002		named "ver" is created by U-Boot showing the U-Boot
1003		version as printed by the "version" command.
1004		Any change to this variable will be reverted at the
1005		next reset.
1006
1007- Real-Time Clock:
1008
1009		When CONFIG_CMD_DATE is selected, the type of the RTC
1010		has to be selected, too. Define exactly one of the
1011		following options:
1012
1013		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
1014		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
1015		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
1016		CONFIG_RTC_MC146818	- use MC146818 RTC
1017		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
1018		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
1019		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
1020		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
1021		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
1022		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
1023		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
1024		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
1025					  RV3029 RTC.
1026
1027		Note that if the RTC uses I2C, then the I2C interface
1028		must also be configured. See I2C Support, below.
1029
1030- GPIO Support:
1031		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
1032		CONFIG_PCA953X_INFO	- enable pca953x info command
1033
1034		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
1035		chip-ngpio pairs that tell the PCA953X driver the number of
1036		pins supported by a particular chip.
1037
1038		Note that if the GPIO device uses I2C, then the I2C interface
1039		must also be configured. See I2C Support, below.
1040
1041- Timestamp Support:
1042
1043		When CONFIG_TIMESTAMP is selected, the timestamp
1044		(date and time) of an image is printed by image
1045		commands like bootm or iminfo. This option is
1046		automatically enabled when you select CONFIG_CMD_DATE .
1047
1048- Partition Labels (disklabels) Supported:
1049		Zero or more of the following:
1050		CONFIG_MAC_PARTITION   Apple's MacOS partition table.
1051		CONFIG_DOS_PARTITION   MS Dos partition table, traditional on the
1052				       Intel architecture, USB sticks, etc.
1053		CONFIG_ISO_PARTITION   ISO partition table, used on CDROM etc.
1054		CONFIG_EFI_PARTITION   GPT partition table, common when EFI is the
1055				       bootloader.  Note 2TB partition limit; see
1056				       disk/part_efi.c
1057		CONFIG_MTD_PARTITIONS  Memory Technology Device partition table.
1058
1059		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
1060		CONFIG_CMD_SCSI) you must configure support for at
1061		least one non-MTD partition type as well.
1062
1063- IDE Reset method:
1064		CONFIG_IDE_RESET_ROUTINE - this is defined in several
1065		board configurations files but used nowhere!
1066
1067		CONFIG_IDE_RESET - is this is defined, IDE Reset will
1068		be performed by calling the function
1069			ide_set_reset(int reset)
1070		which has to be defined in a board specific file
1071
1072- ATAPI Support:
1073		CONFIG_ATAPI
1074
1075		Set this to enable ATAPI support.
1076
1077- LBA48 Support
1078		CONFIG_LBA48
1079
1080		Set this to enable support for disks larger than 137GB
1081		Also look at CONFIG_SYS_64BIT_LBA.
1082		Whithout these , LBA48 support uses 32bit variables and will 'only'
1083		support disks up to 2.1TB.
1084
1085		CONFIG_SYS_64BIT_LBA:
1086			When enabled, makes the IDE subsystem use 64bit sector addresses.
1087			Default is 32bit.
1088
1089- SCSI Support:
1090		At the moment only there is only support for the
1091		SYM53C8XX SCSI controller; define
1092		CONFIG_SCSI_SYM53C8XX to enable it.
1093
1094		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
1095		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
1096		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
1097		maximum numbers of LUNs, SCSI ID's and target
1098		devices.
1099		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
1100
1101                The environment variable 'scsidevs' is set to the number of
1102                SCSI devices found during the last scan.
1103
1104- NETWORK Support (PCI):
1105		CONFIG_E1000
1106		Support for Intel 8254x/8257x gigabit chips.
1107
1108		CONFIG_E1000_SPI
1109		Utility code for direct access to the SPI bus on Intel 8257x.
1110		This does not do anything useful unless you set at least one
1111		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
1112
1113		CONFIG_E1000_SPI_GENERIC
1114		Allow generic access to the SPI bus on the Intel 8257x, for
1115		example with the "sspi" command.
1116
1117		CONFIG_CMD_E1000
1118		Management command for E1000 devices.  When used on devices
1119		with SPI support you can reprogram the EEPROM from U-Boot.
1120
1121		CONFIG_E1000_FALLBACK_MAC
1122		default MAC for empty EEPROM after production.
1123
1124		CONFIG_EEPRO100
1125		Support for Intel 82557/82559/82559ER chips.
1126		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1127		write routine for first time initialisation.
1128
1129		CONFIG_TULIP
1130		Support for Digital 2114x chips.
1131		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1132		modem chip initialisation (KS8761/QS6611).
1133
1134		CONFIG_NATSEMI
1135		Support for National dp83815 chips.
1136
1137		CONFIG_NS8382X
1138		Support for National dp8382[01] gigabit chips.
1139
1140- NETWORK Support (other):
1141
1142		CONFIG_DRIVER_AT91EMAC
1143		Support for AT91RM9200 EMAC.
1144
1145			CONFIG_RMII
1146			Define this to use reduced MII inteface
1147
1148			CONFIG_DRIVER_AT91EMAC_QUIET
1149			If this defined, the driver is quiet.
1150			The driver doen't show link status messages.
1151
1152		CONFIG_CALXEDA_XGMAC
1153		Support for the Calxeda XGMAC device
1154
1155		CONFIG_LAN91C96
1156		Support for SMSC's LAN91C96 chips.
1157
1158			CONFIG_LAN91C96_BASE
1159			Define this to hold the physical address
1160			of the LAN91C96's I/O space
1161
1162			CONFIG_LAN91C96_USE_32_BIT
1163			Define this to enable 32 bit addressing
1164
1165		CONFIG_SMC91111
1166		Support for SMSC's LAN91C111 chip
1167
1168			CONFIG_SMC91111_BASE
1169			Define this to hold the physical address
1170			of the device (I/O space)
1171
1172			CONFIG_SMC_USE_32_BIT
1173			Define this if data bus is 32 bits
1174
1175			CONFIG_SMC_USE_IOFUNCS
1176			Define this to use i/o functions instead of macros
1177			(some hardware wont work with macros)
1178
1179		CONFIG_DRIVER_TI_EMAC
1180		Support for davinci emac
1181
1182			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1183			Define this if you have more then 3 PHYs.
1184
1185		CONFIG_FTGMAC100
1186		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1187
1188			CONFIG_FTGMAC100_EGIGA
1189			Define this to use GE link update with gigabit PHY.
1190			Define this if FTGMAC100 is connected to gigabit PHY.
1191			If your system has 10/100 PHY only, it might not occur
1192			wrong behavior. Because PHY usually return timeout or
1193			useless data when polling gigabit status and gigabit
1194			control registers. This behavior won't affect the
1195			correctnessof 10/100 link speed update.
1196
1197		CONFIG_SMC911X
1198		Support for SMSC's LAN911x and LAN921x chips
1199
1200			CONFIG_SMC911X_BASE
1201			Define this to hold the physical address
1202			of the device (I/O space)
1203
1204			CONFIG_SMC911X_32_BIT
1205			Define this if data bus is 32 bits
1206
1207			CONFIG_SMC911X_16_BIT
1208			Define this if data bus is 16 bits. If your processor
1209			automatically converts one 32 bit word to two 16 bit
1210			words you may also try CONFIG_SMC911X_32_BIT.
1211
1212		CONFIG_SH_ETHER
1213		Support for Renesas on-chip Ethernet controller
1214
1215			CONFIG_SH_ETHER_USE_PORT
1216			Define the number of ports to be used
1217
1218			CONFIG_SH_ETHER_PHY_ADDR
1219			Define the ETH PHY's address
1220
1221			CONFIG_SH_ETHER_CACHE_WRITEBACK
1222			If this option is set, the driver enables cache flush.
1223
1224- TPM Support:
1225		CONFIG_TPM
1226		Support TPM devices.
1227
1228		CONFIG_TPM_TIS_I2C
1229		Support for i2c bus TPM devices. Only one device
1230		per system is supported at this time.
1231
1232			CONFIG_TPM_TIS_I2C_BUS_NUMBER
1233			Define the the i2c bus number for the TPM device
1234
1235			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
1236			Define the TPM's address on the i2c bus
1237
1238			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
1239			Define the burst count bytes upper limit
1240
1241		CONFIG_TPM_ATMEL_TWI
1242		Support for Atmel TWI TPM device. Requires I2C support.
1243
1244		CONFIG_TPM_TIS_LPC
1245		Support for generic parallel port TPM devices. Only one device
1246		per system is supported at this time.
1247
1248			CONFIG_TPM_TIS_BASE_ADDRESS
1249			Base address where the generic TPM device is mapped
1250			to. Contemporary x86 systems usually map it at
1251			0xfed40000.
1252
1253		CONFIG_CMD_TPM
1254		Add tpm monitor functions.
1255		Requires CONFIG_TPM. If CONFIG_TPM_AUTH_SESSIONS is set, also
1256		provides monitor access to authorized functions.
1257
1258		CONFIG_TPM
1259		Define this to enable the TPM support library which provides
1260		functional interfaces to some TPM commands.
1261		Requires support for a TPM device.
1262
1263		CONFIG_TPM_AUTH_SESSIONS
1264		Define this to enable authorized functions in the TPM library.
1265		Requires CONFIG_TPM and CONFIG_SHA1.
1266
1267- USB Support:
1268		At the moment only the UHCI host controller is
1269		supported (PIP405, MIP405, MPC5200); define
1270		CONFIG_USB_UHCI to enable it.
1271		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1272		and define CONFIG_USB_STORAGE to enable the USB
1273		storage devices.
1274		Note:
1275		Supported are USB Keyboards and USB Floppy drives
1276		(TEAC FD-05PUB).
1277		MPC5200 USB requires additional defines:
1278			CONFIG_USB_CLOCK
1279				for 528 MHz Clock: 0x0001bbbb
1280			CONFIG_PSC3_USB
1281				for USB on PSC3
1282			CONFIG_USB_CONFIG
1283				for differential drivers: 0x00001000
1284				for single ended drivers: 0x00005000
1285				for differential drivers on PSC3: 0x00000100
1286				for single ended drivers on PSC3: 0x00004100
1287			CONFIG_SYS_USB_EVENT_POLL
1288				May be defined to allow interrupt polling
1289				instead of using asynchronous interrupts
1290
1291		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1292		txfilltuning field in the EHCI controller on reset.
1293
1294		CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
1295		interval for usb hub power-on delay.(minimum 100msec)
1296
1297- USB Device:
1298		Define the below if you wish to use the USB console.
1299		Once firmware is rebuilt from a serial console issue the
1300		command "setenv stdin usbtty; setenv stdout usbtty" and
1301		attach your USB cable. The Unix command "dmesg" should print
1302		it has found a new device. The environment variable usbtty
1303		can be set to gserial or cdc_acm to enable your device to
1304		appear to a USB host as a Linux gserial device or a
1305		Common Device Class Abstract Control Model serial device.
1306		If you select usbtty = gserial you should be able to enumerate
1307		a Linux host by
1308		# modprobe usbserial vendor=0xVendorID product=0xProductID
1309		else if using cdc_acm, simply setting the environment
1310		variable usbtty to be cdc_acm should suffice. The following
1311		might be defined in YourBoardName.h
1312
1313			CONFIG_USB_DEVICE
1314			Define this to build a UDC device
1315
1316			CONFIG_USB_TTY
1317			Define this to have a tty type of device available to
1318			talk to the UDC device
1319
1320			CONFIG_USBD_HS
1321			Define this to enable the high speed support for usb
1322			device and usbtty. If this feature is enabled, a routine
1323			int is_usbd_high_speed(void)
1324			also needs to be defined by the driver to dynamically poll
1325			whether the enumeration has succeded at high speed or full
1326			speed.
1327
1328			CONFIG_SYS_CONSOLE_IS_IN_ENV
1329			Define this if you want stdin, stdout &/or stderr to
1330			be set to usbtty.
1331
1332			mpc8xx:
1333				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1334				Derive USB clock from external clock "blah"
1335				- CONFIG_SYS_USB_EXTC_CLK 0x02
1336
1337				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1338				Derive USB clock from brgclk
1339				- CONFIG_SYS_USB_BRG_CLK 0x04
1340
1341		If you have a USB-IF assigned VendorID then you may wish to
1342		define your own vendor specific values either in BoardName.h
1343		or directly in usbd_vendor_info.h. If you don't define
1344		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1345		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1346		should pretend to be a Linux device to it's target host.
1347
1348			CONFIG_USBD_MANUFACTURER
1349			Define this string as the name of your company for
1350			- CONFIG_USBD_MANUFACTURER "my company"
1351
1352			CONFIG_USBD_PRODUCT_NAME
1353			Define this string as the name of your product
1354			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1355
1356			CONFIG_USBD_VENDORID
1357			Define this as your assigned Vendor ID from the USB
1358			Implementors Forum. This *must* be a genuine Vendor ID
1359			to avoid polluting the USB namespace.
1360			- CONFIG_USBD_VENDORID 0xFFFF
1361
1362			CONFIG_USBD_PRODUCTID
1363			Define this as the unique Product ID
1364			for your device
1365			- CONFIG_USBD_PRODUCTID 0xFFFF
1366
1367- ULPI Layer Support:
1368		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1369		the generic ULPI layer. The generic layer accesses the ULPI PHY
1370		via the platform viewport, so you need both the genric layer and
1371		the viewport enabled. Currently only Chipidea/ARC based
1372		viewport is supported.
1373		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1374		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1375		If your ULPI phy needs a different reference clock than the
1376		standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
1377		the appropriate value in Hz.
1378
1379- MMC Support:
1380		The MMC controller on the Intel PXA is supported. To
1381		enable this define CONFIG_MMC. The MMC can be
1382		accessed from the boot prompt by mapping the device
1383		to physical memory similar to flash. Command line is
1384		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1385		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1386
1387		CONFIG_SH_MMCIF
1388		Support for Renesas on-chip MMCIF controller
1389
1390			CONFIG_SH_MMCIF_ADDR
1391			Define the base address of MMCIF registers
1392
1393			CONFIG_SH_MMCIF_CLK
1394			Define the clock frequency for MMCIF
1395
1396- USB Device Firmware Update (DFU) class support:
1397		CONFIG_DFU_FUNCTION
1398		This enables the USB portion of the DFU USB class
1399
1400		CONFIG_CMD_DFU
1401		This enables the command "dfu" which is used to have
1402		U-Boot create a DFU class device via USB.  This command
1403		requires that the "dfu_alt_info" environment variable be
1404		set and define the alt settings to expose to the host.
1405
1406		CONFIG_DFU_MMC
1407		This enables support for exposing (e)MMC devices via DFU.
1408
1409		CONFIG_DFU_NAND
1410		This enables support for exposing NAND devices via DFU.
1411
1412		CONFIG_SYS_DFU_DATA_BUF_SIZE
1413		Dfu transfer uses a buffer before writing data to the
1414		raw storage device. Make the size (in bytes) of this buffer
1415		configurable. The size of this buffer is also configurable
1416		through the "dfu_bufsiz" environment variable.
1417
1418		CONFIG_SYS_DFU_MAX_FILE_SIZE
1419		When updating files rather than the raw storage device,
1420		we use a static buffer to copy the file into and then write
1421		the buffer once we've been given the whole file.  Define
1422		this to the maximum filesize (in bytes) for the buffer.
1423		Default is 4 MiB if undefined.
1424
1425- Journaling Flash filesystem support:
1426		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1427		CONFIG_JFFS2_NAND_DEV
1428		Define these for a default partition on a NAND device
1429
1430		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1431		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1432		Define these for a default partition on a NOR device
1433
1434		CONFIG_SYS_JFFS_CUSTOM_PART
1435		Define this to create an own partition. You have to provide a
1436		function struct part_info* jffs2_part_info(int part_num)
1437
1438		If you define only one JFFS2 partition you may also want to
1439		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1440		to disable the command chpart. This is the default when you
1441		have not defined a custom partition
1442
1443- FAT(File Allocation Table) filesystem write function support:
1444		CONFIG_FAT_WRITE
1445
1446		Define this to enable support for saving memory data as a
1447		file in FAT formatted partition.
1448
1449		This will also enable the command "fatwrite" enabling the
1450		user to write files to FAT.
1451
1452CBFS (Coreboot Filesystem) support
1453		CONFIG_CMD_CBFS
1454
1455		Define this to enable support for reading from a Coreboot
1456		filesystem. Available commands are cbfsinit, cbfsinfo, cbfsls
1457		and cbfsload.
1458
1459- Keyboard Support:
1460		CONFIG_ISA_KEYBOARD
1461
1462		Define this to enable standard (PC-Style) keyboard
1463		support
1464
1465		CONFIG_I8042_KBD
1466		Standard PC keyboard driver with US (is default) and
1467		GERMAN key layout (switch via environment 'keymap=de') support.
1468		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1469		for cfb_console. Supports cursor blinking.
1470
1471		CONFIG_CROS_EC_KEYB
1472		Enables a Chrome OS keyboard using the CROS_EC interface.
1473		This uses CROS_EC to communicate with a second microcontroller
1474		which provides key scans on request.
1475
1476- Video support:
1477		CONFIG_VIDEO
1478
1479		Define this to enable video support (for output to
1480		video).
1481
1482		CONFIG_VIDEO_CT69000
1483
1484		Enable Chips & Technologies 69000 Video chip
1485
1486		CONFIG_VIDEO_SMI_LYNXEM
1487		Enable Silicon Motion SMI 712/710/810 Video chip. The
1488		video output is selected via environment 'videoout'
1489		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1490		assumed.
1491
1492		For the CT69000 and SMI_LYNXEM drivers, videomode is
1493		selected via environment 'videomode'. Two different ways
1494		are possible:
1495		- "videomode=num"   'num' is a standard LiLo mode numbers.
1496		Following standard modes are supported	(* is default):
1497
1498		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1499		-------------+---------------------------------------------
1500		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1501		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1502		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1503		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1504		-------------+---------------------------------------------
1505		(i.e. setenv videomode 317; saveenv; reset;)
1506
1507		- "videomode=bootargs" all the video parameters are parsed
1508		from the bootargs. (See drivers/video/videomodes.c)
1509
1510
1511		CONFIG_VIDEO_SED13806
1512		Enable Epson SED13806 driver. This driver supports 8bpp
1513		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1514		or CONFIG_VIDEO_SED13806_16BPP
1515
1516		CONFIG_FSL_DIU_FB
1517		Enable the Freescale DIU video driver.	Reference boards for
1518		SOCs that have a DIU should define this macro to enable DIU
1519		support, and should also define these other macros:
1520
1521			CONFIG_SYS_DIU_ADDR
1522			CONFIG_VIDEO
1523			CONFIG_CMD_BMP
1524			CONFIG_CFB_CONSOLE
1525			CONFIG_VIDEO_SW_CURSOR
1526			CONFIG_VGA_AS_SINGLE_DEVICE
1527			CONFIG_VIDEO_LOGO
1528			CONFIG_VIDEO_BMP_LOGO
1529
1530		The DIU driver will look for the 'video-mode' environment
1531		variable, and if defined, enable the DIU as a console during
1532		boot.  See the documentation file README.video for a
1533		description of this variable.
1534
1535		CONFIG_VIDEO_VGA
1536
1537		Enable the VGA video / BIOS for x86. The alternative if you
1538		are using coreboot is to use the coreboot frame buffer
1539		driver.
1540
1541
1542- Keyboard Support:
1543		CONFIG_KEYBOARD
1544
1545		Define this to enable a custom keyboard support.
1546		This simply calls drv_keyboard_init() which must be
1547		defined in your board-specific files.
1548		The only board using this so far is RBC823.
1549
1550- LCD Support:	CONFIG_LCD
1551
1552		Define this to enable LCD support (for output to LCD
1553		display); also select one of the supported displays
1554		by defining one of these:
1555
1556		CONFIG_ATMEL_LCD:
1557
1558			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1559
1560		CONFIG_NEC_NL6448AC33:
1561
1562			NEC NL6448AC33-18. Active, color, single scan.
1563
1564		CONFIG_NEC_NL6448BC20
1565
1566			NEC NL6448BC20-08. 6.5", 640x480.
1567			Active, color, single scan.
1568
1569		CONFIG_NEC_NL6448BC33_54
1570
1571			NEC NL6448BC33-54. 10.4", 640x480.
1572			Active, color, single scan.
1573
1574		CONFIG_SHARP_16x9
1575
1576			Sharp 320x240. Active, color, single scan.
1577			It isn't 16x9, and I am not sure what it is.
1578
1579		CONFIG_SHARP_LQ64D341
1580
1581			Sharp LQ64D341 display, 640x480.
1582			Active, color, single scan.
1583
1584		CONFIG_HLD1045
1585
1586			HLD1045 display, 640x480.
1587			Active, color, single scan.
1588
1589		CONFIG_OPTREX_BW
1590
1591			Optrex	 CBL50840-2 NF-FW 99 22 M5
1592			or
1593			Hitachi	 LMG6912RPFC-00T
1594			or
1595			Hitachi	 SP14Q002
1596
1597			320x240. Black & white.
1598
1599		Normally display is black on white background; define
1600		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1601
1602		CONFIG_LCD_ALIGNMENT
1603
1604		Normally the LCD is page-aligned (tyically 4KB). If this is
1605		defined then the LCD will be aligned to this value instead.
1606		For ARM it is sometimes useful to use MMU_SECTION_SIZE
1607		here, since it is cheaper to change data cache settings on
1608		a per-section basis.
1609
1610		CONFIG_CONSOLE_SCROLL_LINES
1611
1612		When the console need to be scrolled, this is the number of
1613		lines to scroll by. It defaults to 1. Increasing this makes
1614		the console jump but can help speed up operation when scrolling
1615		is slow.
1616
1617		CONFIG_LCD_BMP_RLE8
1618
1619		Support drawing of RLE8-compressed bitmaps on the LCD.
1620
1621		CONFIG_I2C_EDID
1622
1623		Enables an 'i2c edid' command which can read EDID
1624		information over I2C from an attached LCD display.
1625
1626- Splash Screen Support: CONFIG_SPLASH_SCREEN
1627
1628		If this option is set, the environment is checked for
1629		a variable "splashimage". If found, the usual display
1630		of logo, copyright and system information on the LCD
1631		is suppressed and the BMP image at the address
1632		specified in "splashimage" is loaded instead. The
1633		console is redirected to the "nulldev", too. This
1634		allows for a "silent" boot where a splash screen is
1635		loaded very quickly after power-on.
1636
1637		CONFIG_SPLASHIMAGE_GUARD
1638
1639		If this option is set, then U-Boot will prevent the environment
1640		variable "splashimage" from being set to a problematic address
1641		(see README.displaying-bmps and README.arm-unaligned-accesses).
1642		This option is useful for targets where, due to alignment
1643		restrictions, an improperly aligned BMP image will cause a data
1644		abort. If you think you will not have problems with unaligned
1645		accesses (for example because your toolchain prevents them)
1646		there is no need to set this option.
1647
1648		CONFIG_SPLASH_SCREEN_ALIGN
1649
1650		If this option is set the splash image can be freely positioned
1651		on the screen. Environment variable "splashpos" specifies the
1652		position as "x,y". If a positive number is given it is used as
1653		number of pixel from left/top. If a negative number is given it
1654		is used as number of pixel from right/bottom. You can also
1655		specify 'm' for centering the image.
1656
1657		Example:
1658		setenv splashpos m,m
1659			=> image at center of screen
1660
1661		setenv splashpos 30,20
1662			=> image at x = 30 and y = 20
1663
1664		setenv splashpos -10,m
1665			=> vertically centered image
1666			   at x = dspWidth - bmpWidth - 9
1667
1668- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1669
1670		If this option is set, additionally to standard BMP
1671		images, gzipped BMP images can be displayed via the
1672		splashscreen support or the bmp command.
1673
1674- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1675
1676		If this option is set, 8-bit RLE compressed BMP images
1677		can be displayed via the splashscreen support or the
1678		bmp command.
1679
1680- Do compresssing for memory range:
1681		CONFIG_CMD_ZIP
1682
1683		If this option is set, it would use zlib deflate method
1684		to compress the specified memory at its best effort.
1685
1686- Compression support:
1687		CONFIG_BZIP2
1688
1689		If this option is set, support for bzip2 compressed
1690		images is included. If not, only uncompressed and gzip
1691		compressed images are supported.
1692
1693		NOTE: the bzip2 algorithm requires a lot of RAM, so
1694		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1695		be at least 4MB.
1696
1697		CONFIG_LZMA
1698
1699		If this option is set, support for lzma compressed
1700		images is included.
1701
1702		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1703		requires an amount of dynamic memory that is given by the
1704		formula:
1705
1706			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1707
1708		Where lc and lp stand for, respectively, Literal context bits
1709		and Literal pos bits.
1710
1711		This value is upper-bounded by 14MB in the worst case. Anyway,
1712		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1713		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1714		a very small buffer.
1715
1716		Use the lzmainfo tool to determinate the lc and lp values and
1717		then calculate the amount of needed dynamic memory (ensuring
1718		the appropriate CONFIG_SYS_MALLOC_LEN value).
1719
1720- MII/PHY support:
1721		CONFIG_PHY_ADDR
1722
1723		The address of PHY on MII bus.
1724
1725		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1726
1727		The clock frequency of the MII bus
1728
1729		CONFIG_PHY_GIGE
1730
1731		If this option is set, support for speed/duplex
1732		detection of gigabit PHY is included.
1733
1734		CONFIG_PHY_RESET_DELAY
1735
1736		Some PHY like Intel LXT971A need extra delay after
1737		reset before any MII register access is possible.
1738		For such PHY, set this option to the usec delay
1739		required. (minimum 300usec for LXT971A)
1740
1741		CONFIG_PHY_CMD_DELAY (ppc4xx)
1742
1743		Some PHY like Intel LXT971A need extra delay after
1744		command issued before MII status register can be read
1745
1746- Ethernet address:
1747		CONFIG_ETHADDR
1748		CONFIG_ETH1ADDR
1749		CONFIG_ETH2ADDR
1750		CONFIG_ETH3ADDR
1751		CONFIG_ETH4ADDR
1752		CONFIG_ETH5ADDR
1753
1754		Define a default value for Ethernet address to use
1755		for the respective Ethernet interface, in case this
1756		is not determined automatically.
1757
1758- IP address:
1759		CONFIG_IPADDR
1760
1761		Define a default value for the IP address to use for
1762		the default Ethernet interface, in case this is not
1763		determined through e.g. bootp.
1764		(Environment variable "ipaddr")
1765
1766- Server IP address:
1767		CONFIG_SERVERIP
1768
1769		Defines a default value for the IP address of a TFTP
1770		server to contact when using the "tftboot" command.
1771		(Environment variable "serverip")
1772
1773		CONFIG_KEEP_SERVERADDR
1774
1775		Keeps the server's MAC address, in the env 'serveraddr'
1776		for passing to bootargs (like Linux's netconsole option)
1777
1778- Gateway IP address:
1779		CONFIG_GATEWAYIP
1780
1781		Defines a default value for the IP address of the
1782		default router where packets to other networks are
1783		sent to.
1784		(Environment variable "gatewayip")
1785
1786- Subnet mask:
1787		CONFIG_NETMASK
1788
1789		Defines a default value for the subnet mask (or
1790		routing prefix) which is used to determine if an IP
1791		address belongs to the local subnet or needs to be
1792		forwarded through a router.
1793		(Environment variable "netmask")
1794
1795- Multicast TFTP Mode:
1796		CONFIG_MCAST_TFTP
1797
1798		Defines whether you want to support multicast TFTP as per
1799		rfc-2090; for example to work with atftp.  Lets lots of targets
1800		tftp down the same boot image concurrently.  Note: the Ethernet
1801		driver in use must provide a function: mcast() to join/leave a
1802		multicast group.
1803
1804- BOOTP Recovery Mode:
1805		CONFIG_BOOTP_RANDOM_DELAY
1806
1807		If you have many targets in a network that try to
1808		boot using BOOTP, you may want to avoid that all
1809		systems send out BOOTP requests at precisely the same
1810		moment (which would happen for instance at recovery
1811		from a power failure, when all systems will try to
1812		boot, thus flooding the BOOTP server. Defining
1813		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1814		inserted before sending out BOOTP requests. The
1815		following delays are inserted then:
1816
1817		1st BOOTP request:	delay 0 ... 1 sec
1818		2nd BOOTP request:	delay 0 ... 2 sec
1819		3rd BOOTP request:	delay 0 ... 4 sec
1820		4th and following
1821		BOOTP requests:		delay 0 ... 8 sec
1822
1823- DHCP Advanced Options:
1824		You can fine tune the DHCP functionality by defining
1825		CONFIG_BOOTP_* symbols:
1826
1827		CONFIG_BOOTP_SUBNETMASK
1828		CONFIG_BOOTP_GATEWAY
1829		CONFIG_BOOTP_HOSTNAME
1830		CONFIG_BOOTP_NISDOMAIN
1831		CONFIG_BOOTP_BOOTPATH
1832		CONFIG_BOOTP_BOOTFILESIZE
1833		CONFIG_BOOTP_DNS
1834		CONFIG_BOOTP_DNS2
1835		CONFIG_BOOTP_SEND_HOSTNAME
1836		CONFIG_BOOTP_NTPSERVER
1837		CONFIG_BOOTP_TIMEOFFSET
1838		CONFIG_BOOTP_VENDOREX
1839		CONFIG_BOOTP_MAY_FAIL
1840
1841		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1842		environment variable, not the BOOTP server.
1843
1844		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1845		after the configured retry count, the call will fail
1846		instead of starting over.  This can be used to fail over
1847		to Link-local IP address configuration if the DHCP server
1848		is not available.
1849
1850		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1851		serverip from a DHCP server, it is possible that more
1852		than one DNS serverip is offered to the client.
1853		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1854		serverip will be stored in the additional environment
1855		variable "dnsip2". The first DNS serverip is always
1856		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1857		is defined.
1858
1859		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1860		to do a dynamic update of a DNS server. To do this, they
1861		need the hostname of the DHCP requester.
1862		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1863		of the "hostname" environment variable is passed as
1864		option 12 to the DHCP server.
1865
1866		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1867
1868		A 32bit value in microseconds for a delay between
1869		receiving a "DHCP Offer" and sending the "DHCP Request".
1870		This fixes a problem with certain DHCP servers that don't
1871		respond 100% of the time to a "DHCP request". E.g. On an
1872		AT91RM9200 processor running at 180MHz, this delay needed
1873		to be *at least* 15,000 usec before a Windows Server 2003
1874		DHCP server would reply 100% of the time. I recommend at
1875		least 50,000 usec to be safe. The alternative is to hope
1876		that one of the retries will be successful but note that
1877		the DHCP timeout and retry process takes a longer than
1878		this delay.
1879
1880 - Link-local IP address negotiation:
1881		Negotiate with other link-local clients on the local network
1882		for an address that doesn't require explicit configuration.
1883		This is especially useful if a DHCP server cannot be guaranteed
1884		to exist in all environments that the device must operate.
1885
1886		See doc/README.link-local for more information.
1887
1888 - CDP Options:
1889		CONFIG_CDP_DEVICE_ID
1890
1891		The device id used in CDP trigger frames.
1892
1893		CONFIG_CDP_DEVICE_ID_PREFIX
1894
1895		A two character string which is prefixed to the MAC address
1896		of the device.
1897
1898		CONFIG_CDP_PORT_ID
1899
1900		A printf format string which contains the ascii name of
1901		the port. Normally is set to "eth%d" which sets
1902		eth0 for the first Ethernet, eth1 for the second etc.
1903
1904		CONFIG_CDP_CAPABILITIES
1905
1906		A 32bit integer which indicates the device capabilities;
1907		0x00000010 for a normal host which does not forwards.
1908
1909		CONFIG_CDP_VERSION
1910
1911		An ascii string containing the version of the software.
1912
1913		CONFIG_CDP_PLATFORM
1914
1915		An ascii string containing the name of the platform.
1916
1917		CONFIG_CDP_TRIGGER
1918
1919		A 32bit integer sent on the trigger.
1920
1921		CONFIG_CDP_POWER_CONSUMPTION
1922
1923		A 16bit integer containing the power consumption of the
1924		device in .1 of milliwatts.
1925
1926		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1927
1928		A byte containing the id of the VLAN.
1929
1930- Status LED:	CONFIG_STATUS_LED
1931
1932		Several configurations allow to display the current
1933		status using a LED. For instance, the LED will blink
1934		fast while running U-Boot code, stop blinking as
1935		soon as a reply to a BOOTP request was received, and
1936		start blinking slow once the Linux kernel is running
1937		(supported by a status LED driver in the Linux
1938		kernel). Defining CONFIG_STATUS_LED enables this
1939		feature in U-Boot.
1940
1941- CAN Support:	CONFIG_CAN_DRIVER
1942
1943		Defining CONFIG_CAN_DRIVER enables CAN driver support
1944		on those systems that support this (optional)
1945		feature, like the TQM8xxL modules.
1946
1947- I2C Support:	CONFIG_SYS_I2C
1948
1949		This enable the NEW i2c subsystem, and will allow you to use
1950		i2c commands at the u-boot command line (as long as you set
1951		CONFIG_CMD_I2C in CONFIG_COMMANDS) and communicate with i2c
1952		based realtime clock chips or other i2c devices. See
1953		common/cmd_i2c.c for a description of the command line
1954		interface.
1955
1956		ported i2c driver to the new framework:
1957
1958		additional defines:
1959
1960		CONFIG_SYS_NUM_I2C_BUSES
1961		Hold the number of i2c busses you want to use. If you
1962		don't use/have i2c muxes on your i2c bus, this
1963		is equal to CONFIG_SYS_NUM_I2C_ADAPTERS, and you can
1964		omit this define.
1965
1966		CONFIG_SYS_I2C_DIRECT_BUS
1967		define this, if you don't use i2c muxes on your hardware.
1968		if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1969		omit this define.
1970
1971		CONFIG_SYS_I2C_MAX_HOPS
1972		define how many muxes are maximal consecutively connected
1973		on one i2c bus. If you not use i2c muxes, omit this
1974		define.
1975
1976		CONFIG_SYS_I2C_BUSES
1977		hold a list of busses you want to use, only used if
1978		CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1979		a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1980		CONFIG_SYS_NUM_I2C_BUSES = 9:
1981
1982		 CONFIG_SYS_I2C_BUSES	{{0, {I2C_NULL_HOP}}, \
1983					{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1984					{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1985					{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1986					{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1987					{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1988					{1, {I2C_NULL_HOP}}, \
1989					{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1990					{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1991					}
1992
1993		which defines
1994			bus 0 on adapter 0 without a mux
1995			bus 1 on adapter 0 without a PCA9547 on address 0x70 port 1
1996			bus 2 on adapter 0 without a PCA9547 on address 0x70 port 2
1997			bus 3 on adapter 0 without a PCA9547 on address 0x70 port 3
1998			bus 4 on adapter 0 without a PCA9547 on address 0x70 port 4
1999			bus 5 on adapter 0 without a PCA9547 on address 0x70 port 5
2000			bus 6 on adapter 1 without a mux
2001			bus 7 on adapter 1 without a PCA9544 on address 0x72 port 1
2002			bus 8 on adapter 1 without a PCA9544 on address 0x72 port 2
2003
2004		If you do not have i2c muxes on your board, omit this define.
2005
2006- Legacy I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
2007
2008		NOTE: It is intended to move drivers to CONFIG_SYS_I2C which
2009		provides the following compelling advantages:
2010
2011		- more than one i2c adapter is usable
2012		- approved multibus support
2013		- better i2c mux support
2014
2015		** Please consider updating your I2C driver now. **
2016
2017		These enable legacy I2C serial bus commands. Defining either of
2018		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
2019		include the appropriate I2C driver for the selected CPU.
2020
2021		This will allow you to use i2c commands at the u-boot
2022		command line (as long as you set CONFIG_CMD_I2C in
2023		CONFIG_COMMANDS) and communicate with i2c based realtime
2024		clock chips. See common/cmd_i2c.c for a description of the
2025		command line interface.
2026
2027		CONFIG_HARD_I2C selects a hardware I2C controller.
2028
2029		CONFIG_SOFT_I2C configures u-boot to use a software (aka
2030		bit-banging) driver instead of CPM or similar hardware
2031		support for I2C.
2032
2033		There are several other quantities that must also be
2034		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
2035
2036		In both cases you will need to define CONFIG_SYS_I2C_SPEED
2037		to be the frequency (in Hz) at which you wish your i2c bus
2038		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
2039		the CPU's i2c node address).
2040
2041		Now, the u-boot i2c code for the mpc8xx
2042		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
2043		and so its address should therefore be cleared to 0 (See,
2044		eg, MPC823e User's Manual p.16-473). So, set
2045		CONFIG_SYS_I2C_SLAVE to 0.
2046
2047		CONFIG_SYS_I2C_INIT_MPC5XXX
2048
2049		When a board is reset during an i2c bus transfer
2050		chips might think that the current transfer is still
2051		in progress.  Reset the slave devices by sending start
2052		commands until the slave device responds.
2053
2054		That's all that's required for CONFIG_HARD_I2C.
2055
2056		If you use the software i2c interface (CONFIG_SOFT_I2C)
2057		then the following macros need to be defined (examples are
2058		from include/configs/lwmon.h):
2059
2060		I2C_INIT
2061
2062		(Optional). Any commands necessary to enable the I2C
2063		controller or configure ports.
2064
2065		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
2066
2067		I2C_PORT
2068
2069		(Only for MPC8260 CPU). The I/O port to use (the code
2070		assumes both bits are on the same port). Valid values
2071		are 0..3 for ports A..D.
2072
2073		I2C_ACTIVE
2074
2075		The code necessary to make the I2C data line active
2076		(driven).  If the data line is open collector, this
2077		define can be null.
2078
2079		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
2080
2081		I2C_TRISTATE
2082
2083		The code necessary to make the I2C data line tri-stated
2084		(inactive).  If the data line is open collector, this
2085		define can be null.
2086
2087		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
2088
2089		I2C_READ
2090
2091		Code that returns true if the I2C data line is high,
2092		false if it is low.
2093
2094		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
2095
2096		I2C_SDA(bit)
2097
2098		If <bit> is true, sets the I2C data line high. If it
2099		is false, it clears it (low).
2100
2101		eg: #define I2C_SDA(bit) \
2102			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
2103			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
2104
2105		I2C_SCL(bit)
2106
2107		If <bit> is true, sets the I2C clock line high. If it
2108		is false, it clears it (low).
2109
2110		eg: #define I2C_SCL(bit) \
2111			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
2112			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
2113
2114		I2C_DELAY
2115
2116		This delay is invoked four times per clock cycle so this
2117		controls the rate of data transfer.  The data rate thus
2118		is 1 / (I2C_DELAY * 4). Often defined to be something
2119		like:
2120
2121		#define I2C_DELAY  udelay(2)
2122
2123		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
2124
2125		If your arch supports the generic GPIO framework (asm/gpio.h),
2126		then you may alternatively define the two GPIOs that are to be
2127		used as SCL / SDA.  Any of the previous I2C_xxx macros will
2128		have GPIO-based defaults assigned to them as appropriate.
2129
2130		You should define these to the GPIO value as given directly to
2131		the generic GPIO functions.
2132
2133		CONFIG_SYS_I2C_INIT_BOARD
2134
2135		When a board is reset during an i2c bus transfer
2136		chips might think that the current transfer is still
2137		in progress. On some boards it is possible to access
2138		the i2c SCLK line directly, either by using the
2139		processor pin as a GPIO or by having a second pin
2140		connected to the bus. If this option is defined a
2141		custom i2c_init_board() routine in boards/xxx/board.c
2142		is run early in the boot sequence.
2143
2144		CONFIG_SYS_I2C_BOARD_LATE_INIT
2145
2146		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
2147		defined a custom i2c_board_late_init() routine in
2148		boards/xxx/board.c is run AFTER the operations in i2c_init()
2149		is completed. This callpoint can be used to unreset i2c bus
2150		using CPU i2c controller register accesses for CPUs whose i2c
2151		controller provide such a method. It is called at the end of
2152		i2c_init() to allow i2c_init operations to setup the i2c bus
2153		controller on the CPU (e.g. setting bus speed & slave address).
2154
2155		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
2156
2157		This option enables configuration of bi_iic_fast[] flags
2158		in u-boot bd_info structure based on u-boot environment
2159		variable "i2cfast". (see also i2cfast)
2160
2161		CONFIG_I2C_MULTI_BUS
2162
2163		This option allows the use of multiple I2C buses, each of which
2164		must have a controller.	 At any point in time, only one bus is
2165		active.	 To switch to a different bus, use the 'i2c dev' command.
2166		Note that bus numbering is zero-based.
2167
2168		CONFIG_SYS_I2C_NOPROBES
2169
2170		This option specifies a list of I2C devices that will be skipped
2171		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
2172		is set, specify a list of bus-device pairs.  Otherwise, specify
2173		a 1D array of device addresses
2174
2175		e.g.
2176			#undef	CONFIG_I2C_MULTI_BUS
2177			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
2178
2179		will skip addresses 0x50 and 0x68 on a board with one I2C bus
2180
2181			#define CONFIG_I2C_MULTI_BUS
2182			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
2183
2184		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
2185
2186		CONFIG_SYS_SPD_BUS_NUM
2187
2188		If defined, then this indicates the I2C bus number for DDR SPD.
2189		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
2190
2191		CONFIG_SYS_RTC_BUS_NUM
2192
2193		If defined, then this indicates the I2C bus number for the RTC.
2194		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
2195
2196		CONFIG_SYS_DTT_BUS_NUM
2197
2198		If defined, then this indicates the I2C bus number for the DTT.
2199		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
2200
2201		CONFIG_SYS_I2C_DTT_ADDR:
2202
2203		If defined, specifies the I2C address of the DTT device.
2204		If not defined, then U-Boot uses predefined value for
2205		specified DTT device.
2206
2207		CONFIG_FSL_I2C
2208
2209		Define this option if you want to use Freescale's I2C driver in
2210		drivers/i2c/fsl_i2c.c.
2211
2212		CONFIG_I2C_MUX
2213
2214		Define this option if you have I2C devices reached over 1 .. n
2215		I2C Muxes like the pca9544a. This option addes a new I2C
2216		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
2217		new I2C Bus to the existing I2C Busses. If you select the
2218		new Bus with "i2c dev", u-bbot sends first the commandos for
2219		the muxes to activate this new "bus".
2220
2221		CONFIG_I2C_MULTI_BUS must be also defined, to use this
2222		feature!
2223
2224		Example:
2225		Adding a new I2C Bus reached over 2 pca9544a muxes
2226			The First mux with address 70 and channel 6
2227			The Second mux with address 71 and channel 4
2228
2229		=> i2c bus pca9544a:70:6:pca9544a:71:4
2230
2231		Use the "i2c bus" command without parameter, to get a list
2232		of I2C Busses with muxes:
2233
2234		=> i2c bus
2235		Busses reached over muxes:
2236		Bus ID: 2
2237		  reached over Mux(es):
2238		    pca9544a@70 ch: 4
2239		Bus ID: 3
2240		  reached over Mux(es):
2241		    pca9544a@70 ch: 6
2242		    pca9544a@71 ch: 4
2243		=>
2244
2245		If you now switch to the new I2C Bus 3 with "i2c dev 3"
2246		u-boot first sends the command to the mux@70 to enable
2247		channel 6, and then the command to the mux@71 to enable
2248		the channel 4.
2249
2250		After that, you can use the "normal" i2c commands as
2251		usual to communicate with your I2C devices behind
2252		the 2 muxes.
2253
2254		This option is actually implemented for the bitbanging
2255		algorithm in common/soft_i2c.c and for the Hardware I2C
2256		Bus on the MPC8260. But it should be not so difficult
2257		to add this option to other architectures.
2258
2259		CONFIG_SOFT_I2C_READ_REPEATED_START
2260
2261		defining this will force the i2c_read() function in
2262		the soft_i2c driver to perform an I2C repeated start
2263		between writing the address pointer and reading the
2264		data.  If this define is omitted the default behaviour
2265		of doing a stop-start sequence will be used.  Most I2C
2266		devices can use either method, but some require one or
2267		the other.
2268
2269- SPI Support:	CONFIG_SPI
2270
2271		Enables SPI driver (so far only tested with
2272		SPI EEPROM, also an instance works with Crystal A/D and
2273		D/As on the SACSng board)
2274
2275		CONFIG_SH_SPI
2276
2277		Enables the driver for SPI controller on SuperH. Currently
2278		only SH7757 is supported.
2279
2280		CONFIG_SPI_X
2281
2282		Enables extended (16-bit) SPI EEPROM addressing.
2283		(symmetrical to CONFIG_I2C_X)
2284
2285		CONFIG_SOFT_SPI
2286
2287		Enables a software (bit-bang) SPI driver rather than
2288		using hardware support. This is a general purpose
2289		driver that only requires three general I/O port pins
2290		(two outputs, one input) to function. If this is
2291		defined, the board configuration must define several
2292		SPI configuration items (port pins to use, etc). For
2293		an example, see include/configs/sacsng.h.
2294
2295		CONFIG_HARD_SPI
2296
2297		Enables a hardware SPI driver for general-purpose reads
2298		and writes.  As with CONFIG_SOFT_SPI, the board configuration
2299		must define a list of chip-select function pointers.
2300		Currently supported on some MPC8xxx processors.	 For an
2301		example, see include/configs/mpc8349emds.h.
2302
2303		CONFIG_MXC_SPI
2304
2305		Enables the driver for the SPI controllers on i.MX and MXC
2306		SoCs. Currently i.MX31/35/51 are supported.
2307
2308- FPGA Support: CONFIG_FPGA
2309
2310		Enables FPGA subsystem.
2311
2312		CONFIG_FPGA_<vendor>
2313
2314		Enables support for specific chip vendors.
2315		(ALTERA, XILINX)
2316
2317		CONFIG_FPGA_<family>
2318
2319		Enables support for FPGA family.
2320		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2321
2322		CONFIG_FPGA_COUNT
2323
2324		Specify the number of FPGA devices to support.
2325
2326		CONFIG_SYS_FPGA_PROG_FEEDBACK
2327
2328		Enable printing of hash marks during FPGA configuration.
2329
2330		CONFIG_SYS_FPGA_CHECK_BUSY
2331
2332		Enable checks on FPGA configuration interface busy
2333		status by the configuration function. This option
2334		will require a board or device specific function to
2335		be written.
2336
2337		CONFIG_FPGA_DELAY
2338
2339		If defined, a function that provides delays in the FPGA
2340		configuration driver.
2341
2342		CONFIG_SYS_FPGA_CHECK_CTRLC
2343		Allow Control-C to interrupt FPGA configuration
2344
2345		CONFIG_SYS_FPGA_CHECK_ERROR
2346
2347		Check for configuration errors during FPGA bitfile
2348		loading. For example, abort during Virtex II
2349		configuration if the INIT_B line goes low (which
2350		indicated a CRC error).
2351
2352		CONFIG_SYS_FPGA_WAIT_INIT
2353
2354		Maximum time to wait for the INIT_B line to deassert
2355		after PROB_B has been deasserted during a Virtex II
2356		FPGA configuration sequence. The default time is 500
2357		ms.
2358
2359		CONFIG_SYS_FPGA_WAIT_BUSY
2360
2361		Maximum time to wait for BUSY to deassert during
2362		Virtex II FPGA configuration. The default is 5 ms.
2363
2364		CONFIG_SYS_FPGA_WAIT_CONFIG
2365
2366		Time to wait after FPGA configuration. The default is
2367		200 ms.
2368
2369- Configuration Management:
2370		CONFIG_IDENT_STRING
2371
2372		If defined, this string will be added to the U-Boot
2373		version information (U_BOOT_VERSION)
2374
2375- Vendor Parameter Protection:
2376
2377		U-Boot considers the values of the environment
2378		variables "serial#" (Board Serial Number) and
2379		"ethaddr" (Ethernet Address) to be parameters that
2380		are set once by the board vendor / manufacturer, and
2381		protects these variables from casual modification by
2382		the user. Once set, these variables are read-only,
2383		and write or delete attempts are rejected. You can
2384		change this behaviour:
2385
2386		If CONFIG_ENV_OVERWRITE is #defined in your config
2387		file, the write protection for vendor parameters is
2388		completely disabled. Anybody can change or delete
2389		these parameters.
2390
2391		Alternatively, if you #define _both_ CONFIG_ETHADDR
2392		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2393		Ethernet address is installed in the environment,
2394		which can be changed exactly ONCE by the user. [The
2395		serial# is unaffected by this, i. e. it remains
2396		read-only.]
2397
2398		The same can be accomplished in a more flexible way
2399		for any variable by configuring the type of access
2400		to allow for those variables in the ".flags" variable
2401		or define CONFIG_ENV_FLAGS_LIST_STATIC.
2402
2403- Protected RAM:
2404		CONFIG_PRAM
2405
2406		Define this variable to enable the reservation of
2407		"protected RAM", i. e. RAM which is not overwritten
2408		by U-Boot. Define CONFIG_PRAM to hold the number of
2409		kB you want to reserve for pRAM. You can overwrite
2410		this default value by defining an environment
2411		variable "pram" to the number of kB you want to
2412		reserve. Note that the board info structure will
2413		still show the full amount of RAM. If pRAM is
2414		reserved, a new environment variable "mem" will
2415		automatically be defined to hold the amount of
2416		remaining RAM in a form that can be passed as boot
2417		argument to Linux, for instance like that:
2418
2419			setenv bootargs ... mem=\${mem}
2420			saveenv
2421
2422		This way you can tell Linux not to use this memory,
2423		either, which results in a memory region that will
2424		not be affected by reboots.
2425
2426		*WARNING* If your board configuration uses automatic
2427		detection of the RAM size, you must make sure that
2428		this memory test is non-destructive. So far, the
2429		following board configurations are known to be
2430		"pRAM-clean":
2431
2432			IVMS8, IVML24, SPD8xx, TQM8xxL,
2433			HERMES, IP860, RPXlite, LWMON,
2434			FLAGADM, TQM8260
2435
2436- Access to physical memory region (> 4GB)
2437		Some basic support is provided for operations on memory not
2438		normally accessible to U-Boot - e.g. some architectures
2439		support access to more than 4GB of memory on 32-bit
2440		machines using physical address extension or similar.
2441		Define CONFIG_PHYSMEM to access this basic support, which
2442		currently only supports clearing the memory.
2443
2444- Error Recovery:
2445		CONFIG_PANIC_HANG
2446
2447		Define this variable to stop the system in case of a
2448		fatal error, so that you have to reset it manually.
2449		This is probably NOT a good idea for an embedded
2450		system where you want the system to reboot
2451		automatically as fast as possible, but it may be
2452		useful during development since you can try to debug
2453		the conditions that lead to the situation.
2454
2455		CONFIG_NET_RETRY_COUNT
2456
2457		This variable defines the number of retries for
2458		network operations like ARP, RARP, TFTP, or BOOTP
2459		before giving up the operation. If not defined, a
2460		default value of 5 is used.
2461
2462		CONFIG_ARP_TIMEOUT
2463
2464		Timeout waiting for an ARP reply in milliseconds.
2465
2466		CONFIG_NFS_TIMEOUT
2467
2468		Timeout in milliseconds used in NFS protocol.
2469		If you encounter "ERROR: Cannot umount" in nfs command,
2470		try longer timeout such as
2471		#define CONFIG_NFS_TIMEOUT 10000UL
2472
2473- Command Interpreter:
2474		CONFIG_AUTO_COMPLETE
2475
2476		Enable auto completion of commands using TAB.
2477
2478		Note that this feature has NOT been implemented yet
2479		for the "hush" shell.
2480
2481
2482		CONFIG_SYS_HUSH_PARSER
2483
2484		Define this variable to enable the "hush" shell (from
2485		Busybox) as command line interpreter, thus enabling
2486		powerful command line syntax like
2487		if...then...else...fi conditionals or `&&' and '||'
2488		constructs ("shell scripts").
2489
2490		If undefined, you get the old, much simpler behaviour
2491		with a somewhat smaller memory footprint.
2492
2493
2494		CONFIG_SYS_PROMPT_HUSH_PS2
2495
2496		This defines the secondary prompt string, which is
2497		printed when the command interpreter needs more input
2498		to complete a command. Usually "> ".
2499
2500	Note:
2501
2502		In the current implementation, the local variables
2503		space and global environment variables space are
2504		separated. Local variables are those you define by
2505		simply typing `name=value'. To access a local
2506		variable later on, you have write `$name' or
2507		`${name}'; to execute the contents of a variable
2508		directly type `$name' at the command prompt.
2509
2510		Global environment variables are those you use
2511		setenv/printenv to work with. To run a command stored
2512		in such a variable, you need to use the run command,
2513		and you must not use the '$' sign to access them.
2514
2515		To store commands and special characters in a
2516		variable, please use double quotation marks
2517		surrounding the whole text of the variable, instead
2518		of the backslashes before semicolons and special
2519		symbols.
2520
2521- Commandline Editing and History:
2522		CONFIG_CMDLINE_EDITING
2523
2524		Enable editing and History functions for interactive
2525		commandline input operations
2526
2527- Default Environment:
2528		CONFIG_EXTRA_ENV_SETTINGS
2529
2530		Define this to contain any number of null terminated
2531		strings (variable = value pairs) that will be part of
2532		the default environment compiled into the boot image.
2533
2534		For example, place something like this in your
2535		board's config file:
2536
2537		#define CONFIG_EXTRA_ENV_SETTINGS \
2538			"myvar1=value1\0" \
2539			"myvar2=value2\0"
2540
2541		Warning: This method is based on knowledge about the
2542		internal format how the environment is stored by the
2543		U-Boot code. This is NOT an official, exported
2544		interface! Although it is unlikely that this format
2545		will change soon, there is no guarantee either.
2546		You better know what you are doing here.
2547
2548		Note: overly (ab)use of the default environment is
2549		discouraged. Make sure to check other ways to preset
2550		the environment like the "source" command or the
2551		boot command first.
2552
2553		CONFIG_ENV_VARS_UBOOT_CONFIG
2554
2555		Define this in order to add variables describing the
2556		U-Boot build configuration to the default environment.
2557		These will be named arch, cpu, board, vendor, and soc.
2558
2559		Enabling this option will cause the following to be defined:
2560
2561		- CONFIG_SYS_ARCH
2562		- CONFIG_SYS_CPU
2563		- CONFIG_SYS_BOARD
2564		- CONFIG_SYS_VENDOR
2565		- CONFIG_SYS_SOC
2566
2567		CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG
2568
2569		Define this in order to add variables describing certain
2570		run-time determined information about the hardware to the
2571		environment.  These will be named board_name, board_rev.
2572
2573		CONFIG_DELAY_ENVIRONMENT
2574
2575		Normally the environment is loaded when the board is
2576		intialised so that it is available to U-Boot. This inhibits
2577		that so that the environment is not available until
2578		explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
2579		this is instead controlled by the value of
2580		/config/load-environment.
2581
2582- DataFlash Support:
2583		CONFIG_HAS_DATAFLASH
2584
2585		Defining this option enables DataFlash features and
2586		allows to read/write in Dataflash via the standard
2587		commands cp, md...
2588
2589- Serial Flash support
2590		CONFIG_CMD_SF
2591
2592		Defining this option enables SPI flash commands
2593		'sf probe/read/write/erase/update'.
2594
2595		Usage requires an initial 'probe' to define the serial
2596		flash parameters, followed by read/write/erase/update
2597		commands.
2598
2599		The following defaults may be provided by the platform
2600		to handle the common case when only a single serial
2601		flash is present on the system.
2602
2603		CONFIG_SF_DEFAULT_BUS		Bus identifier
2604		CONFIG_SF_DEFAULT_CS		Chip-select
2605		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2606		CONFIG_SF_DEFAULT_SPEED		in Hz
2607
2608		CONFIG_CMD_SF_TEST
2609
2610		Define this option to include a destructive SPI flash
2611		test ('sf test').
2612
2613		CONFIG_SPI_FLASH_BAR		Ban/Extended Addr Reg
2614
2615		Define this option to use the Bank addr/Extended addr
2616		support on SPI flashes which has size > 16Mbytes.
2617
2618- SystemACE Support:
2619		CONFIG_SYSTEMACE
2620
2621		Adding this option adds support for Xilinx SystemACE
2622		chips attached via some sort of local bus. The address
2623		of the chip must also be defined in the
2624		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2625
2626		#define CONFIG_SYSTEMACE
2627		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2628
2629		When SystemACE support is added, the "ace" device type
2630		becomes available to the fat commands, i.e. fatls.
2631
2632- TFTP Fixed UDP Port:
2633		CONFIG_TFTP_PORT
2634
2635		If this is defined, the environment variable tftpsrcp
2636		is used to supply the TFTP UDP source port value.
2637		If tftpsrcp isn't defined, the normal pseudo-random port
2638		number generator is used.
2639
2640		Also, the environment variable tftpdstp is used to supply
2641		the TFTP UDP destination port value.  If tftpdstp isn't
2642		defined, the normal port 69 is used.
2643
2644		The purpose for tftpsrcp is to allow a TFTP server to
2645		blindly start the TFTP transfer using the pre-configured
2646		target IP address and UDP port. This has the effect of
2647		"punching through" the (Windows XP) firewall, allowing
2648		the remainder of the TFTP transfer to proceed normally.
2649		A better solution is to properly configure the firewall,
2650		but sometimes that is not allowed.
2651
2652- Hashing support:
2653		CONFIG_CMD_HASH
2654
2655		This enables a generic 'hash' command which can produce
2656		hashes / digests from a few algorithms (e.g. SHA1, SHA256).
2657
2658		CONFIG_HASH_VERIFY
2659
2660		Enable the hash verify command (hash -v). This adds to code
2661		size a little.
2662
2663		CONFIG_SHA1 - support SHA1 hashing
2664		CONFIG_SHA256 - support SHA256 hashing
2665
2666		Note: There is also a sha1sum command, which should perhaps
2667		be deprecated in favour of 'hash sha1'.
2668
2669- Signing support:
2670		CONFIG_RSA
2671
2672		This enables the RSA algorithm used for FIT image verification
2673		in U-Boot. See doc/uImage/signature for more information.
2674
2675		The signing part is build into mkimage regardless of this
2676		option.
2677
2678
2679- Show boot progress:
2680		CONFIG_SHOW_BOOT_PROGRESS
2681
2682		Defining this option allows to add some board-
2683		specific code (calling a user-provided function
2684		"show_boot_progress(int)") that enables you to show
2685		the system's boot progress on some display (for
2686		example, some LED's) on your board. At the moment,
2687		the following checkpoints are implemented:
2688
2689- Detailed boot stage timing
2690		CONFIG_BOOTSTAGE
2691		Define this option to get detailed timing of each stage
2692		of the boot process.
2693
2694		CONFIG_BOOTSTAGE_USER_COUNT
2695		This is the number of available user bootstage records.
2696		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2697		a new ID will be allocated from this stash. If you exceed
2698		the limit, recording will stop.
2699
2700		CONFIG_BOOTSTAGE_REPORT
2701		Define this to print a report before boot, similar to this:
2702
2703		Timer summary in microseconds:
2704		       Mark    Elapsed  Stage
2705			  0          0  reset
2706		  3,575,678  3,575,678  board_init_f start
2707		  3,575,695         17  arch_cpu_init A9
2708		  3,575,777         82  arch_cpu_init done
2709		  3,659,598     83,821  board_init_r start
2710		  3,910,375    250,777  main_loop
2711		 29,916,167 26,005,792  bootm_start
2712		 30,361,327    445,160  start_kernel
2713
2714		CONFIG_CMD_BOOTSTAGE
2715		Add a 'bootstage' command which supports printing a report
2716		and un/stashing of bootstage data.
2717
2718		CONFIG_BOOTSTAGE_FDT
2719		Stash the bootstage information in the FDT. A root 'bootstage'
2720		node is created with each bootstage id as a child. Each child
2721		has a 'name' property and either 'mark' containing the
2722		mark time in microsecond, or 'accum' containing the
2723		accumulated time for that bootstage id in microseconds.
2724		For example:
2725
2726		bootstage {
2727			154 {
2728				name = "board_init_f";
2729				mark = <3575678>;
2730			};
2731			170 {
2732				name = "lcd";
2733				accum = <33482>;
2734			};
2735		};
2736
2737		Code in the Linux kernel can find this in /proc/devicetree.
2738
2739Legacy uImage format:
2740
2741  Arg	Where			When
2742    1	common/cmd_bootm.c	before attempting to boot an image
2743   -1	common/cmd_bootm.c	Image header has bad	 magic number
2744    2	common/cmd_bootm.c	Image header has correct magic number
2745   -2	common/cmd_bootm.c	Image header has bad	 checksum
2746    3	common/cmd_bootm.c	Image header has correct checksum
2747   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2748    4	common/cmd_bootm.c	Image data   has correct checksum
2749   -4	common/cmd_bootm.c	Image is for unsupported architecture
2750    5	common/cmd_bootm.c	Architecture check OK
2751   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2752    6	common/cmd_bootm.c	Image Type check OK
2753   -6	common/cmd_bootm.c	gunzip uncompression error
2754   -7	common/cmd_bootm.c	Unimplemented compression type
2755    7	common/cmd_bootm.c	Uncompression OK
2756    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2757   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2758
2759    9	common/image.c		Start initial ramdisk verification
2760  -10	common/image.c		Ramdisk header has bad	   magic number
2761  -11	common/image.c		Ramdisk header has bad	   checksum
2762   10	common/image.c		Ramdisk header is OK
2763  -12	common/image.c		Ramdisk data   has bad	   checksum
2764   11	common/image.c		Ramdisk data   has correct checksum
2765   12	common/image.c		Ramdisk verification complete, start loading
2766  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2767   13	common/image.c		Start multifile image verification
2768   14	common/image.c		No initial ramdisk, no multifile, continue.
2769
2770   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2771
2772  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2773  -31	post/post.c		POST test failed, detected by post_output_backlog()
2774  -32	post/post.c		POST test failed, detected by post_run_single()
2775
2776   34	common/cmd_doc.c	before loading a Image from a DOC device
2777  -35	common/cmd_doc.c	Bad usage of "doc" command
2778   35	common/cmd_doc.c	correct usage of "doc" command
2779  -36	common/cmd_doc.c	No boot device
2780   36	common/cmd_doc.c	correct boot device
2781  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2782   37	common/cmd_doc.c	correct chip ID found, device available
2783  -38	common/cmd_doc.c	Read Error on boot device
2784   38	common/cmd_doc.c	reading Image header from DOC device OK
2785  -39	common/cmd_doc.c	Image header has bad magic number
2786   39	common/cmd_doc.c	Image header has correct magic number
2787  -40	common/cmd_doc.c	Error reading Image from DOC device
2788   40	common/cmd_doc.c	Image header has correct magic number
2789   41	common/cmd_ide.c	before loading a Image from a IDE device
2790  -42	common/cmd_ide.c	Bad usage of "ide" command
2791   42	common/cmd_ide.c	correct usage of "ide" command
2792  -43	common/cmd_ide.c	No boot device
2793   43	common/cmd_ide.c	boot device found
2794  -44	common/cmd_ide.c	Device not available
2795   44	common/cmd_ide.c	Device available
2796  -45	common/cmd_ide.c	wrong partition selected
2797   45	common/cmd_ide.c	partition selected
2798  -46	common/cmd_ide.c	Unknown partition table
2799   46	common/cmd_ide.c	valid partition table found
2800  -47	common/cmd_ide.c	Invalid partition type
2801   47	common/cmd_ide.c	correct partition type
2802  -48	common/cmd_ide.c	Error reading Image Header on boot device
2803   48	common/cmd_ide.c	reading Image Header from IDE device OK
2804  -49	common/cmd_ide.c	Image header has bad magic number
2805   49	common/cmd_ide.c	Image header has correct magic number
2806  -50	common/cmd_ide.c	Image header has bad	 checksum
2807   50	common/cmd_ide.c	Image header has correct checksum
2808  -51	common/cmd_ide.c	Error reading Image from IDE device
2809   51	common/cmd_ide.c	reading Image from IDE device OK
2810   52	common/cmd_nand.c	before loading a Image from a NAND device
2811  -53	common/cmd_nand.c	Bad usage of "nand" command
2812   53	common/cmd_nand.c	correct usage of "nand" command
2813  -54	common/cmd_nand.c	No boot device
2814   54	common/cmd_nand.c	boot device found
2815  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2816   55	common/cmd_nand.c	correct chip ID found, device available
2817  -56	common/cmd_nand.c	Error reading Image Header on boot device
2818   56	common/cmd_nand.c	reading Image Header from NAND device OK
2819  -57	common/cmd_nand.c	Image header has bad magic number
2820   57	common/cmd_nand.c	Image header has correct magic number
2821  -58	common/cmd_nand.c	Error reading Image from NAND device
2822   58	common/cmd_nand.c	reading Image from NAND device OK
2823
2824  -60	common/env_common.c	Environment has a bad CRC, using default
2825
2826   64	net/eth.c		starting with Ethernet configuration.
2827  -64	net/eth.c		no Ethernet found.
2828   65	net/eth.c		Ethernet found.
2829
2830  -80	common/cmd_net.c	usage wrong
2831   80	common/cmd_net.c	before calling NetLoop()
2832  -81	common/cmd_net.c	some error in NetLoop() occurred
2833   81	common/cmd_net.c	NetLoop() back without error
2834  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2835   82	common/cmd_net.c	trying automatic boot
2836   83	common/cmd_net.c	running "source" command
2837  -83	common/cmd_net.c	some error in automatic boot or "source" command
2838   84	common/cmd_net.c	end without errors
2839
2840FIT uImage format:
2841
2842  Arg	Where			When
2843  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2844 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2845  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2846 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2847  102	common/cmd_bootm.c	Kernel unit name specified
2848 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2849  103	common/cmd_bootm.c	Found configuration node
2850  104	common/cmd_bootm.c	Got kernel subimage node offset
2851 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2852  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2853 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2854  106	common/cmd_bootm.c	Architecture check OK
2855 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2856  107	common/cmd_bootm.c	Kernel subimage type OK
2857 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2858  108	common/cmd_bootm.c	Got kernel subimage data/size
2859 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2860 -109	common/cmd_bootm.c	Can't get kernel subimage type
2861 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2862 -111	common/cmd_bootm.c	Can't get kernel subimage os
2863 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2864 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2865
2866  120	common/image.c		Start initial ramdisk verification
2867 -120	common/image.c		Ramdisk FIT image has incorrect format
2868  121	common/image.c		Ramdisk FIT image has correct format
2869  122	common/image.c		No ramdisk subimage unit name, using configuration
2870 -122	common/image.c		Can't get configuration for ramdisk subimage
2871  123	common/image.c		Ramdisk unit name specified
2872 -124	common/image.c		Can't get ramdisk subimage node offset
2873  125	common/image.c		Got ramdisk subimage node offset
2874 -125	common/image.c		Ramdisk subimage hash verification failed
2875  126	common/image.c		Ramdisk subimage hash verification OK
2876 -126	common/image.c		Ramdisk subimage for unsupported architecture
2877  127	common/image.c		Architecture check OK
2878 -127	common/image.c		Can't get ramdisk subimage data/size
2879  128	common/image.c		Got ramdisk subimage data/size
2880  129	common/image.c		Can't get ramdisk load address
2881 -129	common/image.c		Got ramdisk load address
2882
2883 -130	common/cmd_doc.c	Incorrect FIT image format
2884  131	common/cmd_doc.c	FIT image format OK
2885
2886 -140	common/cmd_ide.c	Incorrect FIT image format
2887  141	common/cmd_ide.c	FIT image format OK
2888
2889 -150	common/cmd_nand.c	Incorrect FIT image format
2890  151	common/cmd_nand.c	FIT image format OK
2891
2892- FIT image support:
2893		CONFIG_FIT
2894		Enable support for the FIT uImage format.
2895
2896		CONFIG_FIT_BEST_MATCH
2897		When no configuration is explicitly selected, default to the
2898		one whose fdt's compatibility field best matches that of
2899		U-Boot itself. A match is considered "best" if it matches the
2900		most specific compatibility entry of U-Boot's fdt's root node.
2901		The order of entries in the configuration's fdt is ignored.
2902
2903		CONFIG_FIT_SIGNATURE
2904		This option enables signature verification of FIT uImages,
2905		using a hash signed and verified using RSA. See
2906		doc/uImage.FIT/signature.txt for more details.
2907
2908- Standalone program support:
2909		CONFIG_STANDALONE_LOAD_ADDR
2910
2911		This option defines a board specific value for the
2912		address where standalone program gets loaded, thus
2913		overwriting the architecture dependent default
2914		settings.
2915
2916- Frame Buffer Address:
2917		CONFIG_FB_ADDR
2918
2919		Define CONFIG_FB_ADDR if you want to use specific
2920		address for frame buffer.  This is typically the case
2921		when using a graphics controller has separate video
2922		memory.  U-Boot will then place the frame buffer at
2923		the given address instead of dynamically reserving it
2924		in system RAM by calling lcd_setmem(), which grabs
2925		the memory for the frame buffer depending on the
2926		configured panel size.
2927
2928		Please see board_init_f function.
2929
2930- Automatic software updates via TFTP server
2931		CONFIG_UPDATE_TFTP
2932		CONFIG_UPDATE_TFTP_CNT_MAX
2933		CONFIG_UPDATE_TFTP_MSEC_MAX
2934
2935		These options enable and control the auto-update feature;
2936		for a more detailed description refer to doc/README.update.
2937
2938- MTD Support (mtdparts command, UBI support)
2939		CONFIG_MTD_DEVICE
2940
2941		Adds the MTD device infrastructure from the Linux kernel.
2942		Needed for mtdparts command support.
2943
2944		CONFIG_MTD_PARTITIONS
2945
2946		Adds the MTD partitioning infrastructure from the Linux
2947		kernel. Needed for UBI support.
2948
2949- UBI support
2950		CONFIG_CMD_UBI
2951
2952		Adds commands for interacting with MTD partitions formatted
2953		with the UBI flash translation layer
2954
2955		Requires also defining CONFIG_RBTREE
2956
2957		CONFIG_UBI_SILENCE_MSG
2958
2959		Make the verbose messages from UBI stop printing.  This leaves
2960		warnings and errors enabled.
2961
2962- UBIFS support
2963		CONFIG_CMD_UBIFS
2964
2965		Adds commands for interacting with UBI volumes formatted as
2966		UBIFS.  UBIFS is read-only in u-boot.
2967
2968		Requires UBI support as well as CONFIG_LZO
2969
2970		CONFIG_UBIFS_SILENCE_MSG
2971
2972		Make the verbose messages from UBIFS stop printing.  This leaves
2973		warnings and errors enabled.
2974
2975- SPL framework
2976		CONFIG_SPL
2977		Enable building of SPL globally.
2978
2979		CONFIG_SPL_LDSCRIPT
2980		LDSCRIPT for linking the SPL binary.
2981
2982		CONFIG_SPL_MAX_FOOTPRINT
2983		Maximum size in memory allocated to the SPL, BSS included.
2984		When defined, the linker checks that the actual memory
2985		used by SPL from _start to __bss_end does not exceed it.
2986		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
2987		must not be both defined at the same time.
2988
2989		CONFIG_SPL_MAX_SIZE
2990		Maximum size of the SPL image (text, data, rodata, and
2991		linker lists sections), BSS excluded.
2992		When defined, the linker checks that the actual size does
2993		not exceed it.
2994
2995		CONFIG_SPL_TEXT_BASE
2996		TEXT_BASE for linking the SPL binary.
2997
2998		CONFIG_SPL_RELOC_TEXT_BASE
2999		Address to relocate to.  If unspecified, this is equal to
3000		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
3001
3002		CONFIG_SPL_BSS_START_ADDR
3003		Link address for the BSS within the SPL binary.
3004
3005		CONFIG_SPL_BSS_MAX_SIZE
3006		Maximum size in memory allocated to the SPL BSS.
3007		When defined, the linker checks that the actual memory used
3008		by SPL from __bss_start to __bss_end does not exceed it.
3009		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
3010		must not be both defined at the same time.
3011
3012		CONFIG_SPL_STACK
3013		Adress of the start of the stack SPL will use
3014
3015		CONFIG_SPL_RELOC_STACK
3016		Adress of the start of the stack SPL will use after
3017		relocation.  If unspecified, this is equal to
3018		CONFIG_SPL_STACK.
3019
3020		CONFIG_SYS_SPL_MALLOC_START
3021		Starting address of the malloc pool used in SPL.
3022
3023		CONFIG_SYS_SPL_MALLOC_SIZE
3024		The size of the malloc pool used in SPL.
3025
3026		CONFIG_SPL_FRAMEWORK
3027		Enable the SPL framework under common/.  This framework
3028		supports MMC, NAND and YMODEM loading of U-Boot and NAND
3029		NAND loading of the Linux Kernel.
3030
3031		CONFIG_SPL_DISPLAY_PRINT
3032		For ARM, enable an optional function to print more information
3033		about the running system.
3034
3035		CONFIG_SPL_INIT_MINIMAL
3036		Arch init code should be built for a very small image
3037
3038		CONFIG_SPL_LIBCOMMON_SUPPORT
3039		Support for common/libcommon.o in SPL binary
3040
3041		CONFIG_SPL_LIBDISK_SUPPORT
3042		Support for disk/libdisk.o in SPL binary
3043
3044		CONFIG_SPL_I2C_SUPPORT
3045		Support for drivers/i2c/libi2c.o in SPL binary
3046
3047		CONFIG_SPL_GPIO_SUPPORT
3048		Support for drivers/gpio/libgpio.o in SPL binary
3049
3050		CONFIG_SPL_MMC_SUPPORT
3051		Support for drivers/mmc/libmmc.o in SPL binary
3052
3053		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
3054		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
3055		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
3056		Address, size and partition on the MMC to load U-Boot from
3057		when the MMC is being used in raw mode.
3058
3059		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
3060		Sector to load kernel uImage from when MMC is being
3061		used in raw mode (for Falcon mode)
3062
3063		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
3064		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
3065		Sector and number of sectors to load kernel argument
3066		parameters from when MMC is being used in raw mode
3067		(for falcon mode)
3068
3069		CONFIG_SPL_FAT_SUPPORT
3070		Support for fs/fat/libfat.o in SPL binary
3071
3072		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
3073		Filename to read to load U-Boot when reading from FAT
3074
3075		CONFIG_SPL_FAT_LOAD_KERNEL_NAME
3076		Filename to read to load kernel uImage when reading
3077		from FAT (for Falcon mode)
3078
3079		CONFIG_SPL_FAT_LOAD_ARGS_NAME
3080		Filename to read to load kernel argument parameters
3081		when reading from FAT (for Falcon mode)
3082
3083		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
3084		Set this for NAND SPL on PPC mpc83xx targets, so that
3085		start.S waits for the rest of the SPL to load before
3086		continuing (the hardware starts execution after just
3087		loading the first page rather than the full 4K).
3088
3089		CONFIG_SPL_NAND_BASE
3090		Include nand_base.c in the SPL.  Requires
3091		CONFIG_SPL_NAND_DRIVERS.
3092
3093		CONFIG_SPL_NAND_DRIVERS
3094		SPL uses normal NAND drivers, not minimal drivers.
3095
3096		CONFIG_SPL_NAND_ECC
3097		Include standard software ECC in the SPL
3098
3099		CONFIG_SPL_NAND_SIMPLE
3100		Support for NAND boot using simple NAND drivers that
3101		expose the cmd_ctrl() interface.
3102
3103		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
3104		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
3105		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
3106		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
3107		CONFIG_SYS_NAND_ECCBYTES
3108		Defines the size and behavior of the NAND that SPL uses
3109		to read U-Boot
3110
3111		CONFIG_SYS_NAND_U_BOOT_OFFS
3112		Location in NAND to read U-Boot from
3113
3114		CONFIG_SYS_NAND_U_BOOT_DST
3115		Location in memory to load U-Boot to
3116
3117		CONFIG_SYS_NAND_U_BOOT_SIZE
3118		Size of image to load
3119
3120		CONFIG_SYS_NAND_U_BOOT_START
3121		Entry point in loaded image to jump to
3122
3123		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3124		Define this if you need to first read the OOB and then the
3125		data. This is used for example on davinci plattforms.
3126
3127		CONFIG_SPL_OMAP3_ID_NAND
3128		Support for an OMAP3-specific set of functions to return the
3129		ID and MFR of the first attached NAND chip, if present.
3130
3131		CONFIG_SPL_SERIAL_SUPPORT
3132		Support for drivers/serial/libserial.o in SPL binary
3133
3134		CONFIG_SPL_SPI_FLASH_SUPPORT
3135		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
3136
3137		CONFIG_SPL_SPI_SUPPORT
3138		Support for drivers/spi/libspi.o in SPL binary
3139
3140		CONFIG_SPL_RAM_DEVICE
3141		Support for running image already present in ram, in SPL binary
3142
3143		CONFIG_SPL_LIBGENERIC_SUPPORT
3144		Support for lib/libgeneric.o in SPL binary
3145
3146		CONFIG_SPL_ENV_SUPPORT
3147		Support for the environment operating in SPL binary
3148
3149		CONFIG_SPL_NET_SUPPORT
3150		Support for the net/libnet.o in SPL binary.
3151		It conflicts with SPL env from storage medium specified by
3152		CONFIG_ENV_IS_xxx but CONFIG_ENV_IS_NOWHERE
3153
3154		CONFIG_SPL_PAD_TO
3155		Image offset to which the SPL should be padded before appending
3156		the SPL payload. By default, this is defined as
3157		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
3158		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
3159		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
3160
3161		CONFIG_SPL_TARGET
3162		Final target image containing SPL and payload.  Some SPLs
3163		use an arch-specific makefile fragment instead, for
3164		example if more than one image needs to be produced.
3165
3166		CONFIG_FIT_SPL_PRINT
3167		Printing information about a FIT image adds quite a bit of
3168		code to SPL. So this is normally disabled in SPL. Use this
3169		option to re-enable it. This will affect the output of the
3170		bootm command when booting a FIT image.
3171
3172Modem Support:
3173--------------
3174
3175[so far only for SMDK2400 boards]
3176
3177- Modem support enable:
3178		CONFIG_MODEM_SUPPORT
3179
3180- RTS/CTS Flow control enable:
3181		CONFIG_HWFLOW
3182
3183- Modem debug support:
3184		CONFIG_MODEM_SUPPORT_DEBUG
3185
3186		Enables debugging stuff (char screen[1024], dbg())
3187		for modem support. Useful only with BDI2000.
3188
3189- Interrupt support (PPC):
3190
3191		There are common interrupt_init() and timer_interrupt()
3192		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
3193		for CPU specific initialization. interrupt_init_cpu()
3194		should set decrementer_count to appropriate value. If
3195		CPU resets decrementer automatically after interrupt
3196		(ppc4xx) it should set decrementer_count to zero.
3197		timer_interrupt() calls timer_interrupt_cpu() for CPU
3198		specific handling. If board has watchdog / status_led
3199		/ other_activity_monitor it works automatically from
3200		general timer_interrupt().
3201
3202- General:
3203
3204		In the target system modem support is enabled when a
3205		specific key (key combination) is pressed during
3206		power-on. Otherwise U-Boot will boot normally
3207		(autoboot). The key_pressed() function is called from
3208		board_init(). Currently key_pressed() is a dummy
3209		function, returning 1 and thus enabling modem
3210		initialization.
3211
3212		If there are no modem init strings in the
3213		environment, U-Boot proceed to autoboot; the
3214		previous output (banner, info printfs) will be
3215		suppressed, though.
3216
3217		See also: doc/README.Modem
3218
3219Board initialization settings:
3220------------------------------
3221
3222During Initialization u-boot calls a number of board specific functions
3223to allow the preparation of board specific prerequisites, e.g. pin setup
3224before drivers are initialized. To enable these callbacks the
3225following configuration macros have to be defined. Currently this is
3226architecture specific, so please check arch/your_architecture/lib/board.c
3227typically in board_init_f() and board_init_r().
3228
3229- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
3230- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
3231- CONFIG_BOARD_LATE_INIT: Call board_late_init()
3232- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
3233
3234Configuration Settings:
3235-----------------------
3236
3237- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
3238		undefine this when you're short of memory.
3239
3240- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
3241		width of the commands listed in the 'help' command output.
3242
3243- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
3244		prompt for user input.
3245
3246- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
3247
3248- CONFIG_SYS_PBSIZE:	Buffer size for Console output
3249
3250- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
3251
3252- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
3253		the application (usually a Linux kernel) when it is
3254		booted
3255
3256- CONFIG_SYS_BAUDRATE_TABLE:
3257		List of legal baudrate settings for this board.
3258
3259- CONFIG_SYS_CONSOLE_INFO_QUIET
3260		Suppress display of console information at boot.
3261
3262- CONFIG_SYS_CONSOLE_IS_IN_ENV
3263		If the board specific function
3264			extern int overwrite_console (void);
3265		returns 1, the stdin, stderr and stdout are switched to the
3266		serial port, else the settings in the environment are used.
3267
3268- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
3269		Enable the call to overwrite_console().
3270
3271- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
3272		Enable overwrite of previous console environment settings.
3273
3274- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
3275		Begin and End addresses of the area used by the
3276		simple memory test.
3277
3278- CONFIG_SYS_ALT_MEMTEST:
3279		Enable an alternate, more extensive memory test.
3280
3281- CONFIG_SYS_MEMTEST_SCRATCH:
3282		Scratch address used by the alternate memory test
3283		You only need to set this if address zero isn't writeable
3284
3285- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
3286		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
3287		this specified memory area will get subtracted from the top
3288		(end) of RAM and won't get "touched" at all by U-Boot. By
3289		fixing up gd->ram_size the Linux kernel should gets passed
3290		the now "corrected" memory size and won't touch it either.
3291		This should work for arch/ppc and arch/powerpc. Only Linux
3292		board ports in arch/powerpc with bootwrapper support that
3293		recalculate the memory size from the SDRAM controller setup
3294		will have to get fixed in Linux additionally.
3295
3296		This option can be used as a workaround for the 440EPx/GRx
3297		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
3298		be touched.
3299
3300		WARNING: Please make sure that this value is a multiple of
3301		the Linux page size (normally 4k). If this is not the case,
3302		then the end address of the Linux memory will be located at a
3303		non page size aligned address and this could cause major
3304		problems.
3305
3306- CONFIG_SYS_LOADS_BAUD_CHANGE:
3307		Enable temporary baudrate change while serial download
3308
3309- CONFIG_SYS_SDRAM_BASE:
3310		Physical start address of SDRAM. _Must_ be 0 here.
3311
3312- CONFIG_SYS_MBIO_BASE:
3313		Physical start address of Motherboard I/O (if using a
3314		Cogent motherboard)
3315
3316- CONFIG_SYS_FLASH_BASE:
3317		Physical start address of Flash memory.
3318
3319- CONFIG_SYS_MONITOR_BASE:
3320		Physical start address of boot monitor code (set by
3321		make config files to be same as the text base address
3322		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
3323		CONFIG_SYS_FLASH_BASE when booting from flash.
3324
3325- CONFIG_SYS_MONITOR_LEN:
3326		Size of memory reserved for monitor code, used to
3327		determine _at_compile_time_ (!) if the environment is
3328		embedded within the U-Boot image, or in a separate
3329		flash sector.
3330
3331- CONFIG_SYS_MALLOC_LEN:
3332		Size of DRAM reserved for malloc() use.
3333
3334- CONFIG_SYS_BOOTM_LEN:
3335		Normally compressed uImages are limited to an
3336		uncompressed size of 8 MBytes. If this is not enough,
3337		you can define CONFIG_SYS_BOOTM_LEN in your board config file
3338		to adjust this setting to your needs.
3339
3340- CONFIG_SYS_BOOTMAPSZ:
3341		Maximum size of memory mapped by the startup code of
3342		the Linux kernel; all data that must be processed by
3343		the Linux kernel (bd_info, boot arguments, FDT blob if
3344		used) must be put below this limit, unless "bootm_low"
3345		enviroment variable is defined and non-zero. In such case
3346		all data for the Linux kernel must be between "bootm_low"
3347		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
3348		variable "bootm_mapsize" will override the value of
3349		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
3350		then the value in "bootm_size" will be used instead.
3351
3352- CONFIG_SYS_BOOT_RAMDISK_HIGH:
3353		Enable initrd_high functionality.  If defined then the
3354		initrd_high feature is enabled and the bootm ramdisk subcommand
3355		is enabled.
3356
3357- CONFIG_SYS_BOOT_GET_CMDLINE:
3358		Enables allocating and saving kernel cmdline in space between
3359		"bootm_low" and "bootm_low" + BOOTMAPSZ.
3360
3361- CONFIG_SYS_BOOT_GET_KBD:
3362		Enables allocating and saving a kernel copy of the bd_info in
3363		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
3364
3365- CONFIG_SYS_MAX_FLASH_BANKS:
3366		Max number of Flash memory banks
3367
3368- CONFIG_SYS_MAX_FLASH_SECT:
3369		Max number of sectors on a Flash chip
3370
3371- CONFIG_SYS_FLASH_ERASE_TOUT:
3372		Timeout for Flash erase operations (in ms)
3373
3374- CONFIG_SYS_FLASH_WRITE_TOUT:
3375		Timeout for Flash write operations (in ms)
3376
3377- CONFIG_SYS_FLASH_LOCK_TOUT
3378		Timeout for Flash set sector lock bit operation (in ms)
3379
3380- CONFIG_SYS_FLASH_UNLOCK_TOUT
3381		Timeout for Flash clear lock bits operation (in ms)
3382
3383- CONFIG_SYS_FLASH_PROTECTION
3384		If defined, hardware flash sectors protection is used
3385		instead of U-Boot software protection.
3386
3387- CONFIG_SYS_DIRECT_FLASH_TFTP:
3388
3389		Enable TFTP transfers directly to flash memory;
3390		without this option such a download has to be
3391		performed in two steps: (1) download to RAM, and (2)
3392		copy from RAM to flash.
3393
3394		The two-step approach is usually more reliable, since
3395		you can check if the download worked before you erase
3396		the flash, but in some situations (when system RAM is
3397		too limited to allow for a temporary copy of the
3398		downloaded image) this option may be very useful.
3399
3400- CONFIG_SYS_FLASH_CFI:
3401		Define if the flash driver uses extra elements in the
3402		common flash structure for storing flash geometry.
3403
3404- CONFIG_FLASH_CFI_DRIVER
3405		This option also enables the building of the cfi_flash driver
3406		in the drivers directory
3407
3408- CONFIG_FLASH_CFI_MTD
3409		This option enables the building of the cfi_mtd driver
3410		in the drivers directory. The driver exports CFI flash
3411		to the MTD layer.
3412
3413- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
3414		Use buffered writes to flash.
3415
3416- CONFIG_FLASH_SPANSION_S29WS_N
3417		s29ws-n MirrorBit flash has non-standard addresses for buffered
3418		write commands.
3419
3420- CONFIG_SYS_FLASH_QUIET_TEST
3421		If this option is defined, the common CFI flash doesn't
3422		print it's warning upon not recognized FLASH banks. This
3423		is useful, if some of the configured banks are only
3424		optionally available.
3425
3426- CONFIG_FLASH_SHOW_PROGRESS
3427		If defined (must be an integer), print out countdown
3428		digits and dots.  Recommended value: 45 (9..1) for 80
3429		column displays, 15 (3..1) for 40 column displays.
3430
3431- CONFIG_FLASH_VERIFY
3432		If defined, the content of the flash (destination) is compared
3433		against the source after the write operation. An error message
3434		will be printed when the contents are not identical.
3435		Please note that this option is useless in nearly all cases,
3436		since such flash programming errors usually are detected earlier
3437		while unprotecting/erasing/programming. Please only enable
3438		this option if you really know what you are doing.
3439
3440- CONFIG_SYS_RX_ETH_BUFFER:
3441		Defines the number of Ethernet receive buffers. On some
3442		Ethernet controllers it is recommended to set this value
3443		to 8 or even higher (EEPRO100 or 405 EMAC), since all
3444		buffers can be full shortly after enabling the interface
3445		on high Ethernet traffic.
3446		Defaults to 4 if not defined.
3447
3448- CONFIG_ENV_MAX_ENTRIES
3449
3450	Maximum number of entries in the hash table that is used
3451	internally to store the environment settings. The default
3452	setting is supposed to be generous and should work in most
3453	cases. This setting can be used to tune behaviour; see
3454	lib/hashtable.c for details.
3455
3456- CONFIG_ENV_FLAGS_LIST_DEFAULT
3457- CONFIG_ENV_FLAGS_LIST_STATIC
3458	Enable validation of the values given to enviroment variables when
3459	calling env set.  Variables can be restricted to only decimal,
3460	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
3461	the variables can also be restricted to IP address or MAC address.
3462
3463	The format of the list is:
3464		type_attribute = [s|d|x|b|i|m]
3465		access_atribute = [a|r|o|c]
3466		attributes = type_attribute[access_atribute]
3467		entry = variable_name[:attributes]
3468		list = entry[,list]
3469
3470	The type attributes are:
3471		s - String (default)
3472		d - Decimal
3473		x - Hexadecimal
3474		b - Boolean ([1yYtT|0nNfF])
3475		i - IP address
3476		m - MAC address
3477
3478	The access attributes are:
3479		a - Any (default)
3480		r - Read-only
3481		o - Write-once
3482		c - Change-default
3483
3484	- CONFIG_ENV_FLAGS_LIST_DEFAULT
3485		Define this to a list (string) to define the ".flags"
3486		envirnoment variable in the default or embedded environment.
3487
3488	- CONFIG_ENV_FLAGS_LIST_STATIC
3489		Define this to a list (string) to define validation that
3490		should be done if an entry is not found in the ".flags"
3491		environment variable.  To override a setting in the static
3492		list, simply add an entry for the same variable name to the
3493		".flags" variable.
3494
3495- CONFIG_ENV_ACCESS_IGNORE_FORCE
3496	If defined, don't allow the -f switch to env set override variable
3497	access flags.
3498
3499- CONFIG_SYS_GENERIC_BOARD
3500	This selects the architecture-generic board system instead of the
3501	architecture-specific board files. It is intended to move boards
3502	to this new framework over time. Defining this will disable the
3503	arch/foo/lib/board.c file and use common/board_f.c and
3504	common/board_r.c instead. To use this option your architecture
3505	must support it (i.e. must define __HAVE_ARCH_GENERIC_BOARD in
3506	its config.mk file). If you find problems enabling this option on
3507	your board please report the problem and send patches!
3508
3509- CONFIG_SYS_SYM_OFFSETS
3510	This is set by architectures that use offsets for link symbols
3511	instead of absolute values. So bss_start is obtained using an
3512	offset _bss_start_ofs from CONFIG_SYS_TEXT_BASE, rather than
3513	directly. You should not need to touch this setting.
3514
3515- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
3516	This is set by OMAP boards for the max time that reset should
3517	be asserted. See doc/README.omap-reset-time for details on how
3518	the value can be calulated on a given board.
3519
3520The following definitions that deal with the placement and management
3521of environment data (variable area); in general, we support the
3522following configurations:
3523
3524- CONFIG_BUILD_ENVCRC:
3525
3526	Builds up envcrc with the target environment so that external utils
3527	may easily extract it and embed it in final U-Boot images.
3528
3529- CONFIG_ENV_IS_IN_FLASH:
3530
3531	Define this if the environment is in flash memory.
3532
3533	a) The environment occupies one whole flash sector, which is
3534	   "embedded" in the text segment with the U-Boot code. This
3535	   happens usually with "bottom boot sector" or "top boot
3536	   sector" type flash chips, which have several smaller
3537	   sectors at the start or the end. For instance, such a
3538	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
3539	   such a case you would place the environment in one of the
3540	   4 kB sectors - with U-Boot code before and after it. With
3541	   "top boot sector" type flash chips, you would put the
3542	   environment in one of the last sectors, leaving a gap
3543	   between U-Boot and the environment.
3544
3545	- CONFIG_ENV_OFFSET:
3546
3547	   Offset of environment data (variable area) to the
3548	   beginning of flash memory; for instance, with bottom boot
3549	   type flash chips the second sector can be used: the offset
3550	   for this sector is given here.
3551
3552	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
3553
3554	- CONFIG_ENV_ADDR:
3555
3556	   This is just another way to specify the start address of
3557	   the flash sector containing the environment (instead of
3558	   CONFIG_ENV_OFFSET).
3559
3560	- CONFIG_ENV_SECT_SIZE:
3561
3562	   Size of the sector containing the environment.
3563
3564
3565	b) Sometimes flash chips have few, equal sized, BIG sectors.
3566	   In such a case you don't want to spend a whole sector for
3567	   the environment.
3568
3569	- CONFIG_ENV_SIZE:
3570
3571	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
3572	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
3573	   of this flash sector for the environment. This saves
3574	   memory for the RAM copy of the environment.
3575
3576	   It may also save flash memory if you decide to use this
3577	   when your environment is "embedded" within U-Boot code,
3578	   since then the remainder of the flash sector could be used
3579	   for U-Boot code. It should be pointed out that this is
3580	   STRONGLY DISCOURAGED from a robustness point of view:
3581	   updating the environment in flash makes it always
3582	   necessary to erase the WHOLE sector. If something goes
3583	   wrong before the contents has been restored from a copy in
3584	   RAM, your target system will be dead.
3585
3586	- CONFIG_ENV_ADDR_REDUND
3587	  CONFIG_ENV_SIZE_REDUND
3588
3589	   These settings describe a second storage area used to hold
3590	   a redundant copy of the environment data, so that there is
3591	   a valid backup copy in case there is a power failure during
3592	   a "saveenv" operation.
3593
3594BE CAREFUL! Any changes to the flash layout, and some changes to the
3595source code will make it necessary to adapt <board>/u-boot.lds*
3596accordingly!
3597
3598
3599- CONFIG_ENV_IS_IN_NVRAM:
3600
3601	Define this if you have some non-volatile memory device
3602	(NVRAM, battery buffered SRAM) which you want to use for the
3603	environment.
3604
3605	- CONFIG_ENV_ADDR:
3606	- CONFIG_ENV_SIZE:
3607
3608	  These two #defines are used to determine the memory area you
3609	  want to use for environment. It is assumed that this memory
3610	  can just be read and written to, without any special
3611	  provision.
3612
3613BE CAREFUL! The first access to the environment happens quite early
3614in U-Boot initalization (when we try to get the setting of for the
3615console baudrate). You *MUST* have mapped your NVRAM area then, or
3616U-Boot will hang.
3617
3618Please note that even with NVRAM we still use a copy of the
3619environment in RAM: we could work on NVRAM directly, but we want to
3620keep settings there always unmodified except somebody uses "saveenv"
3621to save the current settings.
3622
3623
3624- CONFIG_ENV_IS_IN_EEPROM:
3625
3626	Use this if you have an EEPROM or similar serial access
3627	device and a driver for it.
3628
3629	- CONFIG_ENV_OFFSET:
3630	- CONFIG_ENV_SIZE:
3631
3632	  These two #defines specify the offset and size of the
3633	  environment area within the total memory of your EEPROM.
3634
3635	- CONFIG_SYS_I2C_EEPROM_ADDR:
3636	  If defined, specified the chip address of the EEPROM device.
3637	  The default address is zero.
3638
3639	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
3640	  If defined, the number of bits used to address bytes in a
3641	  single page in the EEPROM device.  A 64 byte page, for example
3642	  would require six bits.
3643
3644	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
3645	  If defined, the number of milliseconds to delay between
3646	  page writes.	The default is zero milliseconds.
3647
3648	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3649	  The length in bytes of the EEPROM memory array address.  Note
3650	  that this is NOT the chip address length!
3651
3652	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3653	  EEPROM chips that implement "address overflow" are ones
3654	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3655	  address and the extra bits end up in the "chip address" bit
3656	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3657	  byte chips.
3658
3659	  Note that we consider the length of the address field to
3660	  still be one byte because the extra address bits are hidden
3661	  in the chip address.
3662
3663	- CONFIG_SYS_EEPROM_SIZE:
3664	  The size in bytes of the EEPROM device.
3665
3666	- CONFIG_ENV_EEPROM_IS_ON_I2C
3667	  define this, if you have I2C and SPI activated, and your
3668	  EEPROM, which holds the environment, is on the I2C bus.
3669
3670	- CONFIG_I2C_ENV_EEPROM_BUS
3671	  if you have an Environment on an EEPROM reached over
3672	  I2C muxes, you can define here, how to reach this
3673	  EEPROM. For example:
3674
3675	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3676
3677	  EEPROM which holds the environment, is reached over
3678	  a pca9547 i2c mux with address 0x70, channel 3.
3679
3680- CONFIG_ENV_IS_IN_DATAFLASH:
3681
3682	Define this if you have a DataFlash memory device which you
3683	want to use for the environment.
3684
3685	- CONFIG_ENV_OFFSET:
3686	- CONFIG_ENV_ADDR:
3687	- CONFIG_ENV_SIZE:
3688
3689	  These three #defines specify the offset and size of the
3690	  environment area within the total memory of your DataFlash placed
3691	  at the specified address.
3692
3693- CONFIG_ENV_IS_IN_REMOTE:
3694
3695	Define this if you have a remote memory space which you
3696	want to use for the local device's environment.
3697
3698	- CONFIG_ENV_ADDR:
3699	- CONFIG_ENV_SIZE:
3700
3701	  These two #defines specify the address and size of the
3702	  environment area within the remote memory space. The
3703	  local device can get the environment from remote memory
3704	  space by SRIO or PCIE links.
3705
3706BE CAREFUL! For some special cases, the local device can not use
3707"saveenv" command. For example, the local device will get the
3708environment stored in a remote NOR flash by SRIO or PCIE link,
3709but it can not erase, write this NOR flash by SRIO or PCIE interface.
3710
3711- CONFIG_ENV_IS_IN_NAND:
3712
3713	Define this if you have a NAND device which you want to use
3714	for the environment.
3715
3716	- CONFIG_ENV_OFFSET:
3717	- CONFIG_ENV_SIZE:
3718
3719	  These two #defines specify the offset and size of the environment
3720	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3721	  aligned to an erase block boundary.
3722
3723	- CONFIG_ENV_OFFSET_REDUND (optional):
3724
3725	  This setting describes a second storage area of CONFIG_ENV_SIZE
3726	  size used to hold a redundant copy of the environment data, so
3727	  that there is a valid backup copy in case there is a power failure
3728	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3729	  aligned to an erase block boundary.
3730
3731	- CONFIG_ENV_RANGE (optional):
3732
3733	  Specifies the length of the region in which the environment
3734	  can be written.  This should be a multiple of the NAND device's
3735	  block size.  Specifying a range with more erase blocks than
3736	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3737	  the range to be avoided.
3738
3739	- CONFIG_ENV_OFFSET_OOB (optional):
3740
3741	  Enables support for dynamically retrieving the offset of the
3742	  environment from block zero's out-of-band data.  The
3743	  "nand env.oob" command can be used to record this offset.
3744	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3745	  using CONFIG_ENV_OFFSET_OOB.
3746
3747- CONFIG_NAND_ENV_DST
3748
3749	Defines address in RAM to which the nand_spl code should copy the
3750	environment. If redundant environment is used, it will be copied to
3751	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3752
3753- CONFIG_ENV_IS_IN_UBI:
3754
3755	Define this if you have an UBI volume that you want to use for the
3756	environment.  This has the benefit of wear-leveling the environment
3757	accesses, which is important on NAND.
3758
3759	- CONFIG_ENV_UBI_PART:
3760
3761	  Define this to a string that is the mtd partition containing the UBI.
3762
3763	- CONFIG_ENV_UBI_VOLUME:
3764
3765	  Define this to the name of the volume that you want to store the
3766	  environment in.
3767
3768	- CONFIG_ENV_UBI_VOLUME_REDUND:
3769
3770	  Define this to the name of another volume to store a second copy of
3771	  the environment in.  This will enable redundant environments in UBI.
3772	  It is assumed that both volumes are in the same MTD partition.
3773
3774	- CONFIG_UBI_SILENCE_MSG
3775	- CONFIG_UBIFS_SILENCE_MSG
3776
3777	  You will probably want to define these to avoid a really noisy system
3778	  when storing the env in UBI.
3779
3780- CONFIG_ENV_IS_IN_MMC:
3781
3782	Define this if you have an MMC device which you want to use for the
3783	environment.
3784
3785	- CONFIG_SYS_MMC_ENV_DEV:
3786
3787	  Specifies which MMC device the environment is stored in.
3788
3789	- CONFIG_SYS_MMC_ENV_PART (optional):
3790
3791	  Specifies which MMC partition the environment is stored in. If not
3792	  set, defaults to partition 0, the user area. Common values might be
3793	  1 (first MMC boot partition), 2 (second MMC boot partition).
3794
3795	- CONFIG_ENV_OFFSET:
3796	- CONFIG_ENV_SIZE:
3797
3798	  These two #defines specify the offset and size of the environment
3799	  area within the specified MMC device.
3800
3801	  If offset is positive (the usual case), it is treated as relative to
3802	  the start of the MMC partition. If offset is negative, it is treated
3803	  as relative to the end of the MMC partition. This can be useful if
3804	  your board may be fitted with different MMC devices, which have
3805	  different sizes for the MMC partitions, and you always want the
3806	  environment placed at the very end of the partition, to leave the
3807	  maximum possible space before it, to store other data.
3808
3809	  These two values are in units of bytes, but must be aligned to an
3810	  MMC sector boundary.
3811
3812	- CONFIG_ENV_OFFSET_REDUND (optional):
3813
3814	  Specifies a second storage area, of CONFIG_ENV_SIZE size, used to
3815	  hold a redundant copy of the environment data. This provides a
3816	  valid backup copy in case the other copy is corrupted, e.g. due
3817	  to a power failure during a "saveenv" operation.
3818
3819	  This value may also be positive or negative; this is handled in the
3820	  same way as CONFIG_ENV_OFFSET.
3821
3822	  This value is also in units of bytes, but must also be aligned to
3823	  an MMC sector boundary.
3824
3825	- CONFIG_ENV_SIZE_REDUND (optional):
3826
3827	  This value need not be set, even when CONFIG_ENV_OFFSET_REDUND is
3828	  set. If this value is set, it must be set to the same value as
3829	  CONFIG_ENV_SIZE.
3830
3831- CONFIG_SYS_SPI_INIT_OFFSET
3832
3833	Defines offset to the initial SPI buffer area in DPRAM. The
3834	area is used at an early stage (ROM part) if the environment
3835	is configured to reside in the SPI EEPROM: We need a 520 byte
3836	scratch DPRAM area. It is used between the two initialization
3837	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3838	to be a good choice since it makes it far enough from the
3839	start of the data area as well as from the stack pointer.
3840
3841Please note that the environment is read-only until the monitor
3842has been relocated to RAM and a RAM copy of the environment has been
3843created; also, when using EEPROM you will have to use getenv_f()
3844until then to read environment variables.
3845
3846The environment is protected by a CRC32 checksum. Before the monitor
3847is relocated into RAM, as a result of a bad CRC you will be working
3848with the compiled-in default environment - *silently*!!! [This is
3849necessary, because the first environment variable we need is the
3850"baudrate" setting for the console - if we have a bad CRC, we don't
3851have any device yet where we could complain.]
3852
3853Note: once the monitor has been relocated, then it will complain if
3854the default environment is used; a new CRC is computed as soon as you
3855use the "saveenv" command to store a valid environment.
3856
3857- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3858		Echo the inverted Ethernet link state to the fault LED.
3859
3860		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3861		      also needs to be defined.
3862
3863- CONFIG_SYS_FAULT_MII_ADDR:
3864		MII address of the PHY to check for the Ethernet link state.
3865
3866- CONFIG_NS16550_MIN_FUNCTIONS:
3867		Define this if you desire to only have use of the NS16550_init
3868		and NS16550_putc functions for the serial driver located at
3869		drivers/serial/ns16550.c.  This option is useful for saving
3870		space for already greatly restricted images, including but not
3871		limited to NAND_SPL configurations.
3872
3873- CONFIG_DISPLAY_BOARDINFO
3874		Display information about the board that U-Boot is running on
3875		when U-Boot starts up. The board function checkboard() is called
3876		to do this.
3877
3878- CONFIG_DISPLAY_BOARDINFO_LATE
3879		Similar to the previous option, but display this information
3880		later, once stdio is running and output goes to the LCD, if
3881		present.
3882
3883Low Level (hardware related) configuration options:
3884---------------------------------------------------
3885
3886- CONFIG_SYS_CACHELINE_SIZE:
3887		Cache Line Size of the CPU.
3888
3889- CONFIG_SYS_DEFAULT_IMMR:
3890		Default address of the IMMR after system reset.
3891
3892		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3893		and RPXsuper) to be able to adjust the position of
3894		the IMMR register after a reset.
3895
3896- CONFIG_SYS_CCSRBAR_DEFAULT:
3897		Default (power-on reset) physical address of CCSR on Freescale
3898		PowerPC SOCs.
3899
3900- CONFIG_SYS_CCSRBAR:
3901		Virtual address of CCSR.  On a 32-bit build, this is typically
3902		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3903
3904		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3905		for cross-platform code that uses that macro instead.
3906
3907- CONFIG_SYS_CCSRBAR_PHYS:
3908		Physical address of CCSR.  CCSR can be relocated to a new
3909		physical address, if desired.  In this case, this macro should
3910		be set to that address.	 Otherwise, it should be set to the
3911		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3912		is typically relocated on 36-bit builds.  It is recommended
3913		that this macro be defined via the _HIGH and _LOW macros:
3914
3915		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3916			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3917
3918- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3919		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3920		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3921		used in assembly code, so it must not contain typecasts or
3922		integer size suffixes (e.g. "ULL").
3923
3924- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3925		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3926		used in assembly code, so it must not contain typecasts or
3927		integer size suffixes (e.g. "ULL").
3928
3929- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3930		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3931		forced to a value that ensures that CCSR is not relocated.
3932
3933- Floppy Disk Support:
3934		CONFIG_SYS_FDC_DRIVE_NUMBER
3935
3936		the default drive number (default value 0)
3937
3938		CONFIG_SYS_ISA_IO_STRIDE
3939
3940		defines the spacing between FDC chipset registers
3941		(default value 1)
3942
3943		CONFIG_SYS_ISA_IO_OFFSET
3944
3945		defines the offset of register from address. It
3946		depends on which part of the data bus is connected to
3947		the FDC chipset. (default value 0)
3948
3949		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3950		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3951		default value.
3952
3953		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3954		fdc_hw_init() is called at the beginning of the FDC
3955		setup. fdc_hw_init() must be provided by the board
3956		source code. It is used to make hardware dependant
3957		initializations.
3958
3959- CONFIG_IDE_AHB:
3960		Most IDE controllers were designed to be connected with PCI
3961		interface. Only few of them were designed for AHB interface.
3962		When software is doing ATA command and data transfer to
3963		IDE devices through IDE-AHB controller, some additional
3964		registers accessing to these kind of IDE-AHB controller
3965		is requierd.
3966
3967- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3968		DO NOT CHANGE unless you know exactly what you're
3969		doing! (11-4) [MPC8xx/82xx systems only]
3970
3971- CONFIG_SYS_INIT_RAM_ADDR:
3972
3973		Start address of memory area that can be used for
3974		initial data and stack; please note that this must be
3975		writable memory that is working WITHOUT special
3976		initialization, i. e. you CANNOT use normal RAM which
3977		will become available only after programming the
3978		memory controller and running certain initialization
3979		sequences.
3980
3981		U-Boot uses the following memory types:
3982		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3983		- MPC824X: data cache
3984		- PPC4xx:  data cache
3985
3986- CONFIG_SYS_GBL_DATA_OFFSET:
3987
3988		Offset of the initial data structure in the memory
3989		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3990		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3991		data is located at the end of the available space
3992		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3993		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3994		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3995		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3996
3997	Note:
3998		On the MPC824X (or other systems that use the data
3999		cache for initial memory) the address chosen for
4000		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
4001		point to an otherwise UNUSED address space between
4002		the top of RAM and the start of the PCI space.
4003
4004- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
4005
4006- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
4007
4008- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
4009
4010- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
4011
4012- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
4013
4014- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
4015
4016- CONFIG_SYS_OR_TIMING_SDRAM:
4017		SDRAM timing
4018
4019- CONFIG_SYS_MAMR_PTA:
4020		periodic timer for refresh
4021
4022- CONFIG_SYS_DER:	Debug Event Register (37-47)
4023
4024- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
4025  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
4026  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
4027  CONFIG_SYS_BR1_PRELIM:
4028		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
4029
4030- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
4031  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
4032  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
4033		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
4034
4035- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
4036  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
4037		Machine Mode Register and Memory Periodic Timer
4038		Prescaler definitions (SDRAM timing)
4039
4040- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
4041		enable I2C microcode relocation patch (MPC8xx);
4042		define relocation offset in DPRAM [DSP2]
4043
4044- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
4045		enable SMC microcode relocation patch (MPC8xx);
4046		define relocation offset in DPRAM [SMC1]
4047
4048- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
4049		enable SPI microcode relocation patch (MPC8xx);
4050		define relocation offset in DPRAM [SCC4]
4051
4052- CONFIG_SYS_USE_OSCCLK:
4053		Use OSCM clock mode on MBX8xx board. Be careful,
4054		wrong setting might damage your board. Read
4055		doc/README.MBX before setting this variable!
4056
4057- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
4058		Offset of the bootmode word in DPRAM used by post
4059		(Power On Self Tests). This definition overrides
4060		#define'd default value in commproc.h resp.
4061		cpm_8260.h.
4062
4063- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
4064  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
4065  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
4066  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
4067  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
4068  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
4069  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
4070  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
4071		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
4072
4073- CONFIG_PCI_DISABLE_PCIE:
4074		Disable PCI-Express on systems where it is supported but not
4075		required.
4076
4077- CONFIG_PCI_ENUM_ONLY
4078		Only scan through and get the devices on the busses.
4079		Don't do any setup work, presumably because someone or
4080		something has already done it, and we don't need to do it
4081		a second time.	Useful for platforms that are pre-booted
4082		by coreboot or similar.
4083
4084- CONFIG_PCI_INDIRECT_BRIDGE:
4085		Enable support for indirect PCI bridges.
4086
4087- CONFIG_SYS_SRIO:
4088		Chip has SRIO or not
4089
4090- CONFIG_SRIO1:
4091		Board has SRIO 1 port available
4092
4093- CONFIG_SRIO2:
4094		Board has SRIO 2 port available
4095
4096- CONFIG_SRIO_PCIE_BOOT_MASTER
4097		Board can support master function for Boot from SRIO and PCIE
4098
4099- CONFIG_SYS_SRIOn_MEM_VIRT:
4100		Virtual Address of SRIO port 'n' memory region
4101
4102- CONFIG_SYS_SRIOn_MEM_PHYS:
4103		Physical Address of SRIO port 'n' memory region
4104
4105- CONFIG_SYS_SRIOn_MEM_SIZE:
4106		Size of SRIO port 'n' memory region
4107
4108- CONFIG_SYS_NAND_BUSWIDTH_16BIT
4109		Defined to tell the NAND controller that the NAND chip is using
4110		a 16 bit bus.
4111		Not all NAND drivers use this symbol.
4112		Example of drivers that use it:
4113		- drivers/mtd/nand/ndfc.c
4114		- drivers/mtd/nand/mxc_nand.c
4115
4116- CONFIG_SYS_NDFC_EBC0_CFG
4117		Sets the EBC0_CFG register for the NDFC. If not defined
4118		a default value will be used.
4119
4120- CONFIG_SPD_EEPROM
4121		Get DDR timing information from an I2C EEPROM. Common
4122		with pluggable memory modules such as SODIMMs
4123
4124  SPD_EEPROM_ADDRESS
4125		I2C address of the SPD EEPROM
4126
4127- CONFIG_SYS_SPD_BUS_NUM
4128		If SPD EEPROM is on an I2C bus other than the first
4129		one, specify here. Note that the value must resolve
4130		to something your driver can deal with.
4131
4132- CONFIG_SYS_DDR_RAW_TIMING
4133		Get DDR timing information from other than SPD. Common with
4134		soldered DDR chips onboard without SPD. DDR raw timing
4135		parameters are extracted from datasheet and hard-coded into
4136		header files or board specific files.
4137
4138- CONFIG_FSL_DDR_INTERACTIVE
4139		Enable interactive DDR debugging. See doc/README.fsl-ddr.
4140
4141- CONFIG_SYS_83XX_DDR_USES_CS0
4142		Only for 83xx systems. If specified, then DDR should
4143		be configured using CS0 and CS1 instead of CS2 and CS3.
4144
4145- CONFIG_ETHER_ON_FEC[12]
4146		Define to enable FEC[12] on a 8xx series processor.
4147
4148- CONFIG_FEC[12]_PHY
4149		Define to the hardcoded PHY address which corresponds
4150		to the given FEC; i. e.
4151			#define CONFIG_FEC1_PHY 4
4152		means that the PHY with address 4 is connected to FEC1
4153
4154		When set to -1, means to probe for first available.
4155
4156- CONFIG_FEC[12]_PHY_NORXERR
4157		The PHY does not have a RXERR line (RMII only).
4158		(so program the FEC to ignore it).
4159
4160- CONFIG_RMII
4161		Enable RMII mode for all FECs.
4162		Note that this is a global option, we can't
4163		have one FEC in standard MII mode and another in RMII mode.
4164
4165- CONFIG_CRC32_VERIFY
4166		Add a verify option to the crc32 command.
4167		The syntax is:
4168
4169		=> crc32 -v <address> <count> <crc32>
4170
4171		Where address/count indicate a memory area
4172		and crc32 is the correct crc32 which the
4173		area should have.
4174
4175- CONFIG_LOOPW
4176		Add the "loopw" memory command. This only takes effect if
4177		the memory commands are activated globally (CONFIG_CMD_MEM).
4178
4179- CONFIG_MX_CYCLIC
4180		Add the "mdc" and "mwc" memory commands. These are cyclic
4181		"md/mw" commands.
4182		Examples:
4183
4184		=> mdc.b 10 4 500
4185		This command will print 4 bytes (10,11,12,13) each 500 ms.
4186
4187		=> mwc.l 100 12345678 10
4188		This command will write 12345678 to address 100 all 10 ms.
4189
4190		This only takes effect if the memory commands are activated
4191		globally (CONFIG_CMD_MEM).
4192
4193- CONFIG_SKIP_LOWLEVEL_INIT
4194		[ARM, NDS32, MIPS only] If this variable is defined, then certain
4195		low level initializations (like setting up the memory
4196		controller) are omitted and/or U-Boot does not
4197		relocate itself into RAM.
4198
4199		Normally this variable MUST NOT be defined. The only
4200		exception is when U-Boot is loaded (to RAM) by some
4201		other boot loader or by a debugger which performs
4202		these initializations itself.
4203
4204- CONFIG_SPL_BUILD
4205		Modifies the behaviour of start.S when compiling a loader
4206		that is executed before the actual U-Boot. E.g. when
4207		compiling a NAND SPL.
4208
4209- CONFIG_SYS_MPC85XX_NO_RESETVEC
4210		Only for 85xx systems. If this variable is specified, the section
4211		.resetvec is not kept and the section .bootpg is placed in the
4212		previous 4k of the .text section.
4213
4214- CONFIG_ARCH_MAP_SYSMEM
4215		Generally U-Boot (and in particular the md command) uses
4216		effective address. It is therefore not necessary to regard
4217		U-Boot address as virtual addresses that need to be translated
4218		to physical addresses. However, sandbox requires this, since
4219		it maintains its own little RAM buffer which contains all
4220		addressable memory. This option causes some memory accesses
4221		to be mapped through map_sysmem() / unmap_sysmem().
4222
4223- CONFIG_USE_ARCH_MEMCPY
4224  CONFIG_USE_ARCH_MEMSET
4225		If these options are used a optimized version of memcpy/memset will
4226		be used if available. These functions may be faster under some
4227		conditions but may increase the binary size.
4228
4229- CONFIG_X86_RESET_VECTOR
4230		If defined, the x86 reset vector code is included. This is not
4231		needed when U-Boot is running from Coreboot.
4232
4233- CONFIG_SYS_MPUCLK
4234		Defines the MPU clock speed (in MHz).
4235
4236		NOTE : currently only supported on AM335x platforms.
4237
4238Freescale QE/FMAN Firmware Support:
4239-----------------------------------
4240
4241The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
4242loading of "firmware", which is encoded in the QE firmware binary format.
4243This firmware often needs to be loaded during U-Boot booting, so macros
4244are used to identify the storage device (NOR flash, SPI, etc) and the address
4245within that device.
4246
4247- CONFIG_SYS_QE_FMAN_FW_ADDR
4248	The address in the storage device where the firmware is located.  The
4249	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
4250	is also specified.
4251
4252- CONFIG_SYS_QE_FMAN_FW_LENGTH
4253	The maximum possible size of the firmware.  The firmware binary format
4254	has a field that specifies the actual size of the firmware, but it
4255	might not be possible to read any part of the firmware unless some
4256	local storage is allocated to hold the entire firmware first.
4257
4258- CONFIG_SYS_QE_FMAN_FW_IN_NOR
4259	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
4260	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
4261	virtual address in NOR flash.
4262
4263- CONFIG_SYS_QE_FMAN_FW_IN_NAND
4264	Specifies that QE/FMAN firmware is located in NAND flash.
4265	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
4266
4267- CONFIG_SYS_QE_FMAN_FW_IN_MMC
4268	Specifies that QE/FMAN firmware is located on the primary SD/MMC
4269	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4270
4271- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
4272	Specifies that QE/FMAN firmware is located on the primary SPI
4273	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
4274
4275- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
4276	Specifies that QE/FMAN firmware is located in the remote (master)
4277	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
4278	can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
4279	window->master inbound window->master LAW->the ucode address in
4280	master's memory space.
4281
4282Building the Software:
4283======================
4284
4285Building U-Boot has been tested in several native build environments
4286and in many different cross environments. Of course we cannot support
4287all possibly existing versions of cross development tools in all
4288(potentially obsolete) versions. In case of tool chain problems we
4289recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
4290which is extensively used to build and test U-Boot.
4291
4292If you are not using a native environment, it is assumed that you
4293have GNU cross compiling tools available in your path. In this case,
4294you must set the environment variable CROSS_COMPILE in your shell.
4295Note that no changes to the Makefile or any other source files are
4296necessary. For example using the ELDK on a 4xx CPU, please enter:
4297
4298	$ CROSS_COMPILE=ppc_4xx-
4299	$ export CROSS_COMPILE
4300
4301Note: If you wish to generate Windows versions of the utilities in
4302      the tools directory you can use the MinGW toolchain
4303      (http://www.mingw.org).  Set your HOST tools to the MinGW
4304      toolchain and execute 'make tools'.  For example:
4305
4306       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
4307
4308      Binaries such as tools/mkimage.exe will be created which can
4309      be executed on computers running Windows.
4310
4311U-Boot is intended to be simple to build. After installing the
4312sources you must configure U-Boot for one specific board type. This
4313is done by typing:
4314
4315	make NAME_config
4316
4317where "NAME_config" is the name of one of the existing configu-
4318rations; see boards.cfg for supported names.
4319
4320Note: for some board special configuration names may exist; check if
4321      additional information is available from the board vendor; for
4322      instance, the TQM823L systems are available without (standard)
4323      or with LCD support. You can select such additional "features"
4324      when choosing the configuration, i. e.
4325
4326      make TQM823L_config
4327	- will configure for a plain TQM823L, i. e. no LCD support
4328
4329      make TQM823L_LCD_config
4330	- will configure for a TQM823L with U-Boot console on LCD
4331
4332      etc.
4333
4334
4335Finally, type "make all", and you should get some working U-Boot
4336images ready for download to / installation on your system:
4337
4338- "u-boot.bin" is a raw binary image
4339- "u-boot" is an image in ELF binary format
4340- "u-boot.srec" is in Motorola S-Record format
4341
4342By default the build is performed locally and the objects are saved
4343in the source directory. One of the two methods can be used to change
4344this behavior and build U-Boot to some external directory:
4345
43461. Add O= to the make command line invocations:
4347
4348	make O=/tmp/build distclean
4349	make O=/tmp/build NAME_config
4350	make O=/tmp/build all
4351
43522. Set environment variable BUILD_DIR to point to the desired location:
4353
4354	export BUILD_DIR=/tmp/build
4355	make distclean
4356	make NAME_config
4357	make all
4358
4359Note that the command line "O=" setting overrides the BUILD_DIR environment
4360variable.
4361
4362
4363Please be aware that the Makefiles assume you are using GNU make, so
4364for instance on NetBSD you might need to use "gmake" instead of
4365native "make".
4366
4367
4368If the system board that you have is not listed, then you will need
4369to port U-Boot to your hardware platform. To do this, follow these
4370steps:
4371
43721.  Add a new configuration option for your board to the toplevel
4373    "boards.cfg" file, using the existing entries as examples.
4374    Follow the instructions there to keep the boards in order.
43752.  Create a new directory to hold your board specific code. Add any
4376    files you need. In your board directory, you will need at least
4377    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
43783.  Create a new configuration file "include/configs/<board>.h" for
4379    your board
43803.  If you're porting U-Boot to a new CPU, then also create a new
4381    directory to hold your CPU specific code. Add any files you need.
43824.  Run "make <board>_config" with your new name.
43835.  Type "make", and you should get a working "u-boot.srec" file
4384    to be installed on your target system.
43856.  Debug and solve any problems that might arise.
4386    [Of course, this last step is much harder than it sounds.]
4387
4388
4389Testing of U-Boot Modifications, Ports to New Hardware, etc.:
4390==============================================================
4391
4392If you have modified U-Boot sources (for instance added a new board
4393or support for new devices, a new CPU, etc.) you are expected to
4394provide feedback to the other developers. The feedback normally takes
4395the form of a "patch", i. e. a context diff against a certain (latest
4396official or latest in the git repository) version of U-Boot sources.
4397
4398But before you submit such a patch, please verify that your modifi-
4399cation did not break existing code. At least make sure that *ALL* of
4400the supported boards compile WITHOUT ANY compiler warnings. To do so,
4401just run the "MAKEALL" script, which will configure and build U-Boot
4402for ALL supported system. Be warned, this will take a while. You can
4403select which (cross) compiler to use by passing a `CROSS_COMPILE'
4404environment variable to the script, i. e. to use the ELDK cross tools
4405you can type
4406
4407	CROSS_COMPILE=ppc_8xx- MAKEALL
4408
4409or to build on a native PowerPC system you can type
4410
4411	CROSS_COMPILE=' ' MAKEALL
4412
4413When using the MAKEALL script, the default behaviour is to build
4414U-Boot in the source directory. This location can be changed by
4415setting the BUILD_DIR environment variable. Also, for each target
4416built, the MAKEALL script saves two log files (<target>.ERR and
4417<target>.MAKEALL) in the <source dir>/LOG directory. This default
4418location can be changed by setting the MAKEALL_LOGDIR environment
4419variable. For example:
4420
4421	export BUILD_DIR=/tmp/build
4422	export MAKEALL_LOGDIR=/tmp/log
4423	CROSS_COMPILE=ppc_8xx- MAKEALL
4424
4425With the above settings build objects are saved in the /tmp/build,
4426log files are saved in the /tmp/log and the source tree remains clean
4427during the whole build process.
4428
4429
4430See also "U-Boot Porting Guide" below.
4431
4432
4433Monitor Commands - Overview:
4434============================
4435
4436go	- start application at address 'addr'
4437run	- run commands in an environment variable
4438bootm	- boot application image from memory
4439bootp	- boot image via network using BootP/TFTP protocol
4440bootz   - boot zImage from memory
4441tftpboot- boot image via network using TFTP protocol
4442	       and env variables "ipaddr" and "serverip"
4443	       (and eventually "gatewayip")
4444tftpput - upload a file via network using TFTP protocol
4445rarpboot- boot image via network using RARP/TFTP protocol
4446diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
4447loads	- load S-Record file over serial line
4448loadb	- load binary file over serial line (kermit mode)
4449md	- memory display
4450mm	- memory modify (auto-incrementing)
4451nm	- memory modify (constant address)
4452mw	- memory write (fill)
4453cp	- memory copy
4454cmp	- memory compare
4455crc32	- checksum calculation
4456i2c	- I2C sub-system
4457sspi	- SPI utility commands
4458base	- print or set address offset
4459printenv- print environment variables
4460setenv	- set environment variables
4461saveenv - save environment variables to persistent storage
4462protect - enable or disable FLASH write protection
4463erase	- erase FLASH memory
4464flinfo	- print FLASH memory information
4465nand	- NAND memory operations (see doc/README.nand)
4466bdinfo	- print Board Info structure
4467iminfo	- print header information for application image
4468coninfo - print console devices and informations
4469ide	- IDE sub-system
4470loop	- infinite loop on address range
4471loopw	- infinite write loop on address range
4472mtest	- simple RAM test
4473icache	- enable or disable instruction cache
4474dcache	- enable or disable data cache
4475reset	- Perform RESET of the CPU
4476echo	- echo args to console
4477version - print monitor version
4478help	- print online help
4479?	- alias for 'help'
4480
4481
4482Monitor Commands - Detailed Description:
4483========================================
4484
4485TODO.
4486
4487For now: just type "help <command>".
4488
4489
4490Environment Variables:
4491======================
4492
4493U-Boot supports user configuration using Environment Variables which
4494can be made persistent by saving to Flash memory.
4495
4496Environment Variables are set using "setenv", printed using
4497"printenv", and saved to Flash using "saveenv". Using "setenv"
4498without a value can be used to delete a variable from the
4499environment. As long as you don't save the environment you are
4500working with an in-memory copy. In case the Flash area containing the
4501environment is erased by accident, a default environment is provided.
4502
4503Some configuration options can be set using Environment Variables.
4504
4505List of environment variables (most likely not complete):
4506
4507  baudrate	- see CONFIG_BAUDRATE
4508
4509  bootdelay	- see CONFIG_BOOTDELAY
4510
4511  bootcmd	- see CONFIG_BOOTCOMMAND
4512
4513  bootargs	- Boot arguments when booting an RTOS image
4514
4515  bootfile	- Name of the image to load with TFTP
4516
4517  bootm_low	- Memory range available for image processing in the bootm
4518		  command can be restricted. This variable is given as
4519		  a hexadecimal number and defines lowest address allowed
4520		  for use by the bootm command. See also "bootm_size"
4521		  environment variable. Address defined by "bootm_low" is
4522		  also the base of the initial memory mapping for the Linux
4523		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
4524		  bootm_mapsize.
4525
4526  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
4527		  This variable is given as a hexadecimal number and it
4528		  defines the size of the memory region starting at base
4529		  address bootm_low that is accessible by the Linux kernel
4530		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
4531		  as the default value if it is defined, and bootm_size is
4532		  used otherwise.
4533
4534  bootm_size	- Memory range available for image processing in the bootm
4535		  command can be restricted. This variable is given as
4536		  a hexadecimal number and defines the size of the region
4537		  allowed for use by the bootm command. See also "bootm_low"
4538		  environment variable.
4539
4540  updatefile	- Location of the software update file on a TFTP server, used
4541		  by the automatic software update feature. Please refer to
4542		  documentation in doc/README.update for more details.
4543
4544  autoload	- if set to "no" (any string beginning with 'n'),
4545		  "bootp" will just load perform a lookup of the
4546		  configuration from the BOOTP server, but not try to
4547		  load any image using TFTP
4548
4549  autostart	- if set to "yes", an image loaded using the "bootp",
4550		  "rarpboot", "tftpboot" or "diskboot" commands will
4551		  be automatically started (by internally calling
4552		  "bootm")
4553
4554		  If set to "no", a standalone image passed to the
4555		  "bootm" command will be copied to the load address
4556		  (and eventually uncompressed), but NOT be started.
4557		  This can be used to load and uncompress arbitrary
4558		  data.
4559
4560  fdt_high	- if set this restricts the maximum address that the
4561		  flattened device tree will be copied into upon boot.
4562		  For example, if you have a system with 1 GB memory
4563		  at physical address 0x10000000, while Linux kernel
4564		  only recognizes the first 704 MB as low memory, you
4565		  may need to set fdt_high as 0x3C000000 to have the
4566		  device tree blob be copied to the maximum address
4567		  of the 704 MB low memory, so that Linux kernel can
4568		  access it during the boot procedure.
4569
4570		  If this is set to the special value 0xFFFFFFFF then
4571		  the fdt will not be copied at all on boot.  For this
4572		  to work it must reside in writable memory, have
4573		  sufficient padding on the end of it for u-boot to
4574		  add the information it needs into it, and the memory
4575		  must be accessible by the kernel.
4576
4577  fdtcontroladdr- if set this is the address of the control flattened
4578		  device tree used by U-Boot when CONFIG_OF_CONTROL is
4579		  defined.
4580
4581  i2cfast	- (PPC405GP|PPC405EP only)
4582		  if set to 'y' configures Linux I2C driver for fast
4583		  mode (400kHZ). This environment variable is used in
4584		  initialization code. So, for changes to be effective
4585		  it must be saved and board must be reset.
4586
4587  initrd_high	- restrict positioning of initrd images:
4588		  If this variable is not set, initrd images will be
4589		  copied to the highest possible address in RAM; this
4590		  is usually what you want since it allows for
4591		  maximum initrd size. If for some reason you want to
4592		  make sure that the initrd image is loaded below the
4593		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
4594		  variable to a value of "no" or "off" or "0".
4595		  Alternatively, you can set it to a maximum upper
4596		  address to use (U-Boot will still check that it
4597		  does not overwrite the U-Boot stack and data).
4598
4599		  For instance, when you have a system with 16 MB
4600		  RAM, and want to reserve 4 MB from use by Linux,
4601		  you can do this by adding "mem=12M" to the value of
4602		  the "bootargs" variable. However, now you must make
4603		  sure that the initrd image is placed in the first
4604		  12 MB as well - this can be done with
4605
4606		  setenv initrd_high 00c00000
4607
4608		  If you set initrd_high to 0xFFFFFFFF, this is an
4609		  indication to U-Boot that all addresses are legal
4610		  for the Linux kernel, including addresses in flash
4611		  memory. In this case U-Boot will NOT COPY the
4612		  ramdisk at all. This may be useful to reduce the
4613		  boot time on your system, but requires that this
4614		  feature is supported by your Linux kernel.
4615
4616  ipaddr	- IP address; needed for tftpboot command
4617
4618  loadaddr	- Default load address for commands like "bootp",
4619		  "rarpboot", "tftpboot", "loadb" or "diskboot"
4620
4621  loads_echo	- see CONFIG_LOADS_ECHO
4622
4623  serverip	- TFTP server IP address; needed for tftpboot command
4624
4625  bootretry	- see CONFIG_BOOT_RETRY_TIME
4626
4627  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
4628
4629  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
4630
4631  ethprime	- controls which interface is used first.
4632
4633  ethact	- controls which interface is currently active.
4634		  For example you can do the following
4635
4636		  => setenv ethact FEC
4637		  => ping 192.168.0.1 # traffic sent on FEC
4638		  => setenv ethact SCC
4639		  => ping 10.0.0.1 # traffic sent on SCC
4640
4641  ethrotate	- When set to "no" U-Boot does not go through all
4642		  available network interfaces.
4643		  It just stays at the currently selected interface.
4644
4645  netretry	- When set to "no" each network operation will
4646		  either succeed or fail without retrying.
4647		  When set to "once" the network operation will
4648		  fail when all the available network interfaces
4649		  are tried once without success.
4650		  Useful on scripts which control the retry operation
4651		  themselves.
4652
4653  npe_ucode	- set load address for the NPE microcode
4654
4655  tftpsrcport	- If this is set, the value is used for TFTP's
4656		  UDP source port.
4657
4658  tftpdstport	- If this is set, the value is used for TFTP's UDP
4659		  destination port instead of the Well Know Port 69.
4660
4661  tftpblocksize - Block size to use for TFTP transfers; if not set,
4662		  we use the TFTP server's default block size
4663
4664  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
4665		  seconds, minimum value is 1000 = 1 second). Defines
4666		  when a packet is considered to be lost so it has to
4667		  be retransmitted. The default is 5000 = 5 seconds.
4668		  Lowering this value may make downloads succeed
4669		  faster in networks with high packet loss rates or
4670		  with unreliable TFTP servers.
4671
4672  vlan		- When set to a value < 4095 the traffic over
4673		  Ethernet is encapsulated/received over 802.1q
4674		  VLAN tagged frames.
4675
4676The following image location variables contain the location of images
4677used in booting. The "Image" column gives the role of the image and is
4678not an environment variable name. The other columns are environment
4679variable names. "File Name" gives the name of the file on a TFTP
4680server, "RAM Address" gives the location in RAM the image will be
4681loaded to, and "Flash Location" gives the image's address in NOR
4682flash or offset in NAND flash.
4683
4684*Note* - these variables don't have to be defined for all boards, some
4685boards currenlty use other variables for these purposes, and some
4686boards use these variables for other purposes.
4687
4688Image		    File Name	     RAM Address       Flash Location
4689-----		    ---------	     -----------       --------------
4690u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
4691Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
4692device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
4693ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
4694
4695The following environment variables may be used and automatically
4696updated by the network boot commands ("bootp" and "rarpboot"),
4697depending the information provided by your boot server:
4698
4699  bootfile	- see above
4700  dnsip		- IP address of your Domain Name Server
4701  dnsip2	- IP address of your secondary Domain Name Server
4702  gatewayip	- IP address of the Gateway (Router) to use
4703  hostname	- Target hostname
4704  ipaddr	- see above
4705  netmask	- Subnet Mask
4706  rootpath	- Pathname of the root filesystem on the NFS server
4707  serverip	- see above
4708
4709
4710There are two special Environment Variables:
4711
4712  serial#	- contains hardware identification information such
4713		  as type string and/or serial number
4714  ethaddr	- Ethernet address
4715
4716These variables can be set only once (usually during manufacturing of
4717the board). U-Boot refuses to delete or overwrite these variables
4718once they have been set once.
4719
4720
4721Further special Environment Variables:
4722
4723  ver		- Contains the U-Boot version string as printed
4724		  with the "version" command. This variable is
4725		  readonly (see CONFIG_VERSION_VARIABLE).
4726
4727
4728Please note that changes to some configuration parameters may take
4729only effect after the next boot (yes, that's just like Windoze :-).
4730
4731
4732Callback functions for environment variables:
4733---------------------------------------------
4734
4735For some environment variables, the behavior of u-boot needs to change
4736when their values are changed.  This functionailty allows functions to
4737be associated with arbitrary variables.  On creation, overwrite, or
4738deletion, the callback will provide the opportunity for some side
4739effect to happen or for the change to be rejected.
4740
4741The callbacks are named and associated with a function using the
4742U_BOOT_ENV_CALLBACK macro in your board or driver code.
4743
4744These callbacks are associated with variables in one of two ways.  The
4745static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
4746in the board configuration to a string that defines a list of
4747associations.  The list must be in the following format:
4748
4749	entry = variable_name[:callback_name]
4750	list = entry[,list]
4751
4752If the callback name is not specified, then the callback is deleted.
4753Spaces are also allowed anywhere in the list.
4754
4755Callbacks can also be associated by defining the ".callbacks" variable
4756with the same list format above.  Any association in ".callbacks" will
4757override any association in the static list. You can define
4758CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
4759".callbacks" envirnoment variable in the default or embedded environment.
4760
4761
4762Command Line Parsing:
4763=====================
4764
4765There are two different command line parsers available with U-Boot:
4766the old "simple" one, and the much more powerful "hush" shell:
4767
4768Old, simple command line parser:
4769--------------------------------
4770
4771- supports environment variables (through setenv / saveenv commands)
4772- several commands on one line, separated by ';'
4773- variable substitution using "... ${name} ..." syntax
4774- special characters ('$', ';') can be escaped by prefixing with '\',
4775  for example:
4776	setenv bootcmd bootm \${address}
4777- You can also escape text by enclosing in single apostrophes, for example:
4778	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
4779
4780Hush shell:
4781-----------
4782
4783- similar to Bourne shell, with control structures like
4784  if...then...else...fi, for...do...done; while...do...done,
4785  until...do...done, ...
4786- supports environment ("global") variables (through setenv / saveenv
4787  commands) and local shell variables (through standard shell syntax
4788  "name=value"); only environment variables can be used with "run"
4789  command
4790
4791General rules:
4792--------------
4793
4794(1) If a command line (or an environment variable executed by a "run"
4795    command) contains several commands separated by semicolon, and
4796    one of these commands fails, then the remaining commands will be
4797    executed anyway.
4798
4799(2) If you execute several variables with one call to run (i. e.
4800    calling run with a list of variables as arguments), any failing
4801    command will cause "run" to terminate, i. e. the remaining
4802    variables are not executed.
4803
4804Note for Redundant Ethernet Interfaces:
4805=======================================
4806
4807Some boards come with redundant Ethernet interfaces; U-Boot supports
4808such configurations and is capable of automatic selection of a
4809"working" interface when needed. MAC assignment works as follows:
4810
4811Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4812MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4813"eth1addr" (=>eth1), "eth2addr", ...
4814
4815If the network interface stores some valid MAC address (for instance
4816in SROM), this is used as default address if there is NO correspon-
4817ding setting in the environment; if the corresponding environment
4818variable is set, this overrides the settings in the card; that means:
4819
4820o If the SROM has a valid MAC address, and there is no address in the
4821  environment, the SROM's address is used.
4822
4823o If there is no valid address in the SROM, and a definition in the
4824  environment exists, then the value from the environment variable is
4825  used.
4826
4827o If both the SROM and the environment contain a MAC address, and
4828  both addresses are the same, this MAC address is used.
4829
4830o If both the SROM and the environment contain a MAC address, and the
4831  addresses differ, the value from the environment is used and a
4832  warning is printed.
4833
4834o If neither SROM nor the environment contain a MAC address, an error
4835  is raised.
4836
4837If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4838will be programmed into hardware as part of the initialization process.	 This
4839may be skipped by setting the appropriate 'ethmacskip' environment variable.
4840The naming convention is as follows:
4841"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4842
4843Image Formats:
4844==============
4845
4846U-Boot is capable of booting (and performing other auxiliary operations on)
4847images in two formats:
4848
4849New uImage format (FIT)
4850-----------------------
4851
4852Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4853to Flattened Device Tree). It allows the use of images with multiple
4854components (several kernels, ramdisks, etc.), with contents protected by
4855SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4856
4857
4858Old uImage format
4859-----------------
4860
4861Old image format is based on binary files which can be basically anything,
4862preceded by a special header; see the definitions in include/image.h for
4863details; basically, the header defines the following image properties:
4864
4865* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4866  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4867  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4868  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4869  INTEGRITY).
4870* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4871  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4872  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4873* Compression Type (uncompressed, gzip, bzip2)
4874* Load Address
4875* Entry Point
4876* Image Name
4877* Image Timestamp
4878
4879The header is marked by a special Magic Number, and both the header
4880and the data portions of the image are secured against corruption by
4881CRC32 checksums.
4882
4883
4884Linux Support:
4885==============
4886
4887Although U-Boot should support any OS or standalone application
4888easily, the main focus has always been on Linux during the design of
4889U-Boot.
4890
4891U-Boot includes many features that so far have been part of some
4892special "boot loader" code within the Linux kernel. Also, any
4893"initrd" images to be used are no longer part of one big Linux image;
4894instead, kernel and "initrd" are separate images. This implementation
4895serves several purposes:
4896
4897- the same features can be used for other OS or standalone
4898  applications (for instance: using compressed images to reduce the
4899  Flash memory footprint)
4900
4901- it becomes much easier to port new Linux kernel versions because
4902  lots of low-level, hardware dependent stuff are done by U-Boot
4903
4904- the same Linux kernel image can now be used with different "initrd"
4905  images; of course this also means that different kernel images can
4906  be run with the same "initrd". This makes testing easier (you don't
4907  have to build a new "zImage.initrd" Linux image when you just
4908  change a file in your "initrd"). Also, a field-upgrade of the
4909  software is easier now.
4910
4911
4912Linux HOWTO:
4913============
4914
4915Porting Linux to U-Boot based systems:
4916---------------------------------------
4917
4918U-Boot cannot save you from doing all the necessary modifications to
4919configure the Linux device drivers for use with your target hardware
4920(no, we don't intend to provide a full virtual machine interface to
4921Linux :-).
4922
4923But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4924
4925Just make sure your machine specific header file (for instance
4926include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4927Information structure as we define in include/asm-<arch>/u-boot.h,
4928and make sure that your definition of IMAP_ADDR uses the same value
4929as your U-Boot configuration in CONFIG_SYS_IMMR.
4930
4931
4932Configuring the Linux kernel:
4933-----------------------------
4934
4935No specific requirements for U-Boot. Make sure you have some root
4936device (initial ramdisk, NFS) for your target system.
4937
4938
4939Building a Linux Image:
4940-----------------------
4941
4942With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4943not used. If you use recent kernel source, a new build target
4944"uImage" will exist which automatically builds an image usable by
4945U-Boot. Most older kernels also have support for a "pImage" target,
4946which was introduced for our predecessor project PPCBoot and uses a
4947100% compatible format.
4948
4949Example:
4950
4951	make TQM850L_config
4952	make oldconfig
4953	make dep
4954	make uImage
4955
4956The "uImage" build target uses a special tool (in 'tools/mkimage') to
4957encapsulate a compressed Linux kernel image with header	 information,
4958CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4959
4960* build a standard "vmlinux" kernel image (in ELF binary format):
4961
4962* convert the kernel into a raw binary image:
4963
4964	${CROSS_COMPILE}-objcopy -O binary \
4965				 -R .note -R .comment \
4966				 -S vmlinux linux.bin
4967
4968* compress the binary image:
4969
4970	gzip -9 linux.bin
4971
4972* package compressed binary image for U-Boot:
4973
4974	mkimage -A ppc -O linux -T kernel -C gzip \
4975		-a 0 -e 0 -n "Linux Kernel Image" \
4976		-d linux.bin.gz uImage
4977
4978
4979The "mkimage" tool can also be used to create ramdisk images for use
4980with U-Boot, either separated from the Linux kernel image, or
4981combined into one file. "mkimage" encapsulates the images with a 64
4982byte header containing information about target architecture,
4983operating system, image type, compression method, entry points, time
4984stamp, CRC32 checksums, etc.
4985
4986"mkimage" can be called in two ways: to verify existing images and
4987print the header information, or to build new images.
4988
4989In the first form (with "-l" option) mkimage lists the information
4990contained in the header of an existing U-Boot image; this includes
4991checksum verification:
4992
4993	tools/mkimage -l image
4994	  -l ==> list image header information
4995
4996The second form (with "-d" option) is used to build a U-Boot image
4997from a "data file" which is used as image payload:
4998
4999	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
5000		      -n name -d data_file image
5001	  -A ==> set architecture to 'arch'
5002	  -O ==> set operating system to 'os'
5003	  -T ==> set image type to 'type'
5004	  -C ==> set compression type 'comp'
5005	  -a ==> set load address to 'addr' (hex)
5006	  -e ==> set entry point to 'ep' (hex)
5007	  -n ==> set image name to 'name'
5008	  -d ==> use image data from 'datafile'
5009
5010Right now, all Linux kernels for PowerPC systems use the same load
5011address (0x00000000), but the entry point address depends on the
5012kernel version:
5013
5014- 2.2.x kernels have the entry point at 0x0000000C,
5015- 2.3.x and later kernels have the entry point at 0x00000000.
5016
5017So a typical call to build a U-Boot image would read:
5018
5019	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5020	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
5021	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
5022	> examples/uImage.TQM850L
5023	Image Name:   2.4.4 kernel for TQM850L
5024	Created:      Wed Jul 19 02:34:59 2000
5025	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5026	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5027	Load Address: 0x00000000
5028	Entry Point:  0x00000000
5029
5030To verify the contents of the image (or check for corruption):
5031
5032	-> tools/mkimage -l examples/uImage.TQM850L
5033	Image Name:   2.4.4 kernel for TQM850L
5034	Created:      Wed Jul 19 02:34:59 2000
5035	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
5036	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
5037	Load Address: 0x00000000
5038	Entry Point:  0x00000000
5039
5040NOTE: for embedded systems where boot time is critical you can trade
5041speed for memory and install an UNCOMPRESSED image instead: this
5042needs more space in Flash, but boots much faster since it does not
5043need to be uncompressed:
5044
5045	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
5046	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
5047	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
5048	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
5049	> examples/uImage.TQM850L-uncompressed
5050	Image Name:   2.4.4 kernel for TQM850L
5051	Created:      Wed Jul 19 02:34:59 2000
5052	Image Type:   PowerPC Linux Kernel Image (uncompressed)
5053	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
5054	Load Address: 0x00000000
5055	Entry Point:  0x00000000
5056
5057
5058Similar you can build U-Boot images from a 'ramdisk.image.gz' file
5059when your kernel is intended to use an initial ramdisk:
5060
5061	-> tools/mkimage -n 'Simple Ramdisk Image' \
5062	> -A ppc -O linux -T ramdisk -C gzip \
5063	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
5064	Image Name:   Simple Ramdisk Image
5065	Created:      Wed Jan 12 14:01:50 2000
5066	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
5067	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
5068	Load Address: 0x00000000
5069	Entry Point:  0x00000000
5070
5071
5072Installing a Linux Image:
5073-------------------------
5074
5075To downloading a U-Boot image over the serial (console) interface,
5076you must convert the image to S-Record format:
5077
5078	objcopy -I binary -O srec examples/image examples/image.srec
5079
5080The 'objcopy' does not understand the information in the U-Boot
5081image header, so the resulting S-Record file will be relative to
5082address 0x00000000. To load it to a given address, you need to
5083specify the target address as 'offset' parameter with the 'loads'
5084command.
5085
5086Example: install the image to address 0x40100000 (which on the
5087TQM8xxL is in the first Flash bank):
5088
5089	=> erase 40100000 401FFFFF
5090
5091	.......... done
5092	Erased 8 sectors
5093
5094	=> loads 40100000
5095	## Ready for S-Record download ...
5096	~>examples/image.srec
5097	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
5098	...
5099	15989 15990 15991 15992
5100	[file transfer complete]
5101	[connected]
5102	## Start Addr = 0x00000000
5103
5104
5105You can check the success of the download using the 'iminfo' command;
5106this includes a checksum verification so you can be sure no data
5107corruption happened:
5108
5109	=> imi 40100000
5110
5111	## Checking Image at 40100000 ...
5112	   Image Name:	 2.2.13 for initrd on TQM850L
5113	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5114	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5115	   Load Address: 00000000
5116	   Entry Point:	 0000000c
5117	   Verifying Checksum ... OK
5118
5119
5120Boot Linux:
5121-----------
5122
5123The "bootm" command is used to boot an application that is stored in
5124memory (RAM or Flash). In case of a Linux kernel image, the contents
5125of the "bootargs" environment variable is passed to the kernel as
5126parameters. You can check and modify this variable using the
5127"printenv" and "setenv" commands:
5128
5129
5130	=> printenv bootargs
5131	bootargs=root=/dev/ram
5132
5133	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5134
5135	=> printenv bootargs
5136	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5137
5138	=> bootm 40020000
5139	## Booting Linux kernel at 40020000 ...
5140	   Image Name:	 2.2.13 for NFS on TQM850L
5141	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5142	   Data Size:	 381681 Bytes = 372 kB = 0 MB
5143	   Load Address: 00000000
5144	   Entry Point:	 0000000c
5145	   Verifying Checksum ... OK
5146	   Uncompressing Kernel Image ... OK
5147	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
5148	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
5149	time_init: decrementer frequency = 187500000/60
5150	Calibrating delay loop... 49.77 BogoMIPS
5151	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
5152	...
5153
5154If you want to boot a Linux kernel with initial RAM disk, you pass
5155the memory addresses of both the kernel and the initrd image (PPBCOOT
5156format!) to the "bootm" command:
5157
5158	=> imi 40100000 40200000
5159
5160	## Checking Image at 40100000 ...
5161	   Image Name:	 2.2.13 for initrd on TQM850L
5162	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5163	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5164	   Load Address: 00000000
5165	   Entry Point:	 0000000c
5166	   Verifying Checksum ... OK
5167
5168	## Checking Image at 40200000 ...
5169	   Image Name:	 Simple Ramdisk Image
5170	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5171	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5172	   Load Address: 00000000
5173	   Entry Point:	 00000000
5174	   Verifying Checksum ... OK
5175
5176	=> bootm 40100000 40200000
5177	## Booting Linux kernel at 40100000 ...
5178	   Image Name:	 2.2.13 for initrd on TQM850L
5179	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5180	   Data Size:	 335725 Bytes = 327 kB = 0 MB
5181	   Load Address: 00000000
5182	   Entry Point:	 0000000c
5183	   Verifying Checksum ... OK
5184	   Uncompressing Kernel Image ... OK
5185	## Loading RAMDisk Image at 40200000 ...
5186	   Image Name:	 Simple Ramdisk Image
5187	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
5188	   Data Size:	 566530 Bytes = 553 kB = 0 MB
5189	   Load Address: 00000000
5190	   Entry Point:	 00000000
5191	   Verifying Checksum ... OK
5192	   Loading Ramdisk ... OK
5193	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
5194	Boot arguments: root=/dev/ram
5195	time_init: decrementer frequency = 187500000/60
5196	Calibrating delay loop... 49.77 BogoMIPS
5197	...
5198	RAMDISK: Compressed image found at block 0
5199	VFS: Mounted root (ext2 filesystem).
5200
5201	bash#
5202
5203Boot Linux and pass a flat device tree:
5204-----------
5205
5206First, U-Boot must be compiled with the appropriate defines. See the section
5207titled "Linux Kernel Interface" above for a more in depth explanation. The
5208following is an example of how to start a kernel and pass an updated
5209flat device tree:
5210
5211=> print oftaddr
5212oftaddr=0x300000
5213=> print oft
5214oft=oftrees/mpc8540ads.dtb
5215=> tftp $oftaddr $oft
5216Speed: 1000, full duplex
5217Using TSEC0 device
5218TFTP from server 192.168.1.1; our IP address is 192.168.1.101
5219Filename 'oftrees/mpc8540ads.dtb'.
5220Load address: 0x300000
5221Loading: #
5222done
5223Bytes transferred = 4106 (100a hex)
5224=> tftp $loadaddr $bootfile
5225Speed: 1000, full duplex
5226Using TSEC0 device
5227TFTP from server 192.168.1.1; our IP address is 192.168.1.2
5228Filename 'uImage'.
5229Load address: 0x200000
5230Loading:############
5231done
5232Bytes transferred = 1029407 (fb51f hex)
5233=> print loadaddr
5234loadaddr=200000
5235=> print oftaddr
5236oftaddr=0x300000
5237=> bootm $loadaddr - $oftaddr
5238## Booting image at 00200000 ...
5239   Image Name:	 Linux-2.6.17-dirty
5240   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
5241   Data Size:	 1029343 Bytes = 1005.2 kB
5242   Load Address: 00000000
5243   Entry Point:	 00000000
5244   Verifying Checksum ... OK
5245   Uncompressing Kernel Image ... OK
5246Booting using flat device tree at 0x300000
5247Using MPC85xx ADS machine description
5248Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
5249[snip]
5250
5251
5252More About U-Boot Image Types:
5253------------------------------
5254
5255U-Boot supports the following image types:
5256
5257   "Standalone Programs" are directly runnable in the environment
5258	provided by U-Boot; it is expected that (if they behave
5259	well) you can continue to work in U-Boot after return from
5260	the Standalone Program.
5261   "OS Kernel Images" are usually images of some Embedded OS which
5262	will take over control completely. Usually these programs
5263	will install their own set of exception handlers, device
5264	drivers, set up the MMU, etc. - this means, that you cannot
5265	expect to re-enter U-Boot except by resetting the CPU.
5266   "RAMDisk Images" are more or less just data blocks, and their
5267	parameters (address, size) are passed to an OS kernel that is
5268	being started.
5269   "Multi-File Images" contain several images, typically an OS
5270	(Linux) kernel image and one or more data images like
5271	RAMDisks. This construct is useful for instance when you want
5272	to boot over the network using BOOTP etc., where the boot
5273	server provides just a single image file, but you want to get
5274	for instance an OS kernel and a RAMDisk image.
5275
5276	"Multi-File Images" start with a list of image sizes, each
5277	image size (in bytes) specified by an "uint32_t" in network
5278	byte order. This list is terminated by an "(uint32_t)0".
5279	Immediately after the terminating 0 follow the images, one by
5280	one, all aligned on "uint32_t" boundaries (size rounded up to
5281	a multiple of 4 bytes).
5282
5283   "Firmware Images" are binary images containing firmware (like
5284	U-Boot or FPGA images) which usually will be programmed to
5285	flash memory.
5286
5287   "Script files" are command sequences that will be executed by
5288	U-Boot's command interpreter; this feature is especially
5289	useful when you configure U-Boot to use a real shell (hush)
5290	as command interpreter.
5291
5292Booting the Linux zImage:
5293-------------------------
5294
5295On some platforms, it's possible to boot Linux zImage. This is done
5296using the "bootz" command. The syntax of "bootz" command is the same
5297as the syntax of "bootm" command.
5298
5299Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
5300kernel with raw initrd images. The syntax is slightly different, the
5301address of the initrd must be augmented by it's size, in the following
5302format: "<initrd addres>:<initrd size>".
5303
5304
5305Standalone HOWTO:
5306=================
5307
5308One of the features of U-Boot is that you can dynamically load and
5309run "standalone" applications, which can use some resources of
5310U-Boot like console I/O functions or interrupt services.
5311
5312Two simple examples are included with the sources:
5313
5314"Hello World" Demo:
5315-------------------
5316
5317'examples/hello_world.c' contains a small "Hello World" Demo
5318application; it is automatically compiled when you build U-Boot.
5319It's configured to run at address 0x00040004, so you can play with it
5320like that:
5321
5322	=> loads
5323	## Ready for S-Record download ...
5324	~>examples/hello_world.srec
5325	1 2 3 4 5 6 7 8 9 10 11 ...
5326	[file transfer complete]
5327	[connected]
5328	## Start Addr = 0x00040004
5329
5330	=> go 40004 Hello World! This is a test.
5331	## Starting application at 0x00040004 ...
5332	Hello World
5333	argc = 7
5334	argv[0] = "40004"
5335	argv[1] = "Hello"
5336	argv[2] = "World!"
5337	argv[3] = "This"
5338	argv[4] = "is"
5339	argv[5] = "a"
5340	argv[6] = "test."
5341	argv[7] = "<NULL>"
5342	Hit any key to exit ...
5343
5344	## Application terminated, rc = 0x0
5345
5346Another example, which demonstrates how to register a CPM interrupt
5347handler with the U-Boot code, can be found in 'examples/timer.c'.
5348Here, a CPM timer is set up to generate an interrupt every second.
5349The interrupt service routine is trivial, just printing a '.'
5350character, but this is just a demo program. The application can be
5351controlled by the following keys:
5352
5353	? - print current values og the CPM Timer registers
5354	b - enable interrupts and start timer
5355	e - stop timer and disable interrupts
5356	q - quit application
5357
5358	=> loads
5359	## Ready for S-Record download ...
5360	~>examples/timer.srec
5361	1 2 3 4 5 6 7 8 9 10 11 ...
5362	[file transfer complete]
5363	[connected]
5364	## Start Addr = 0x00040004
5365
5366	=> go 40004
5367	## Starting application at 0x00040004 ...
5368	TIMERS=0xfff00980
5369	Using timer 1
5370	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
5371
5372Hit 'b':
5373	[q, b, e, ?] Set interval 1000000 us
5374	Enabling timer
5375Hit '?':
5376	[q, b, e, ?] ........
5377	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
5378Hit '?':
5379	[q, b, e, ?] .
5380	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
5381Hit '?':
5382	[q, b, e, ?] .
5383	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
5384Hit '?':
5385	[q, b, e, ?] .
5386	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
5387Hit 'e':
5388	[q, b, e, ?] ...Stopping timer
5389Hit 'q':
5390	[q, b, e, ?] ## Application terminated, rc = 0x0
5391
5392
5393Minicom warning:
5394================
5395
5396Over time, many people have reported problems when trying to use the
5397"minicom" terminal emulation program for serial download. I (wd)
5398consider minicom to be broken, and recommend not to use it. Under
5399Unix, I recommend to use C-Kermit for general purpose use (and
5400especially for kermit binary protocol download ("loadb" command), and
5401use "cu" for S-Record download ("loads" command).  See
5402http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
5403for help with kermit.
5404
5405
5406Nevertheless, if you absolutely want to use it try adding this
5407configuration to your "File transfer protocols" section:
5408
5409	   Name	   Program			Name U/D FullScr IO-Red. Multi
5410	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
5411	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
5412
5413
5414NetBSD Notes:
5415=============
5416
5417Starting at version 0.9.2, U-Boot supports NetBSD both as host
5418(build U-Boot) and target system (boots NetBSD/mpc8xx).
5419
5420Building requires a cross environment; it is known to work on
5421NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
5422need gmake since the Makefiles are not compatible with BSD make).
5423Note that the cross-powerpc package does not install include files;
5424attempting to build U-Boot will fail because <machine/ansi.h> is
5425missing.  This file has to be installed and patched manually:
5426
5427	# cd /usr/pkg/cross/powerpc-netbsd/include
5428	# mkdir powerpc
5429	# ln -s powerpc machine
5430	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
5431	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
5432
5433Native builds *don't* work due to incompatibilities between native
5434and U-Boot include files.
5435
5436Booting assumes that (the first part of) the image booted is a
5437stage-2 loader which in turn loads and then invokes the kernel
5438proper. Loader sources will eventually appear in the NetBSD source
5439tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
5440meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
5441
5442
5443Implementation Internals:
5444=========================
5445
5446The following is not intended to be a complete description of every
5447implementation detail. However, it should help to understand the
5448inner workings of U-Boot and make it easier to port it to custom
5449hardware.
5450
5451
5452Initial Stack, Global Data:
5453---------------------------
5454
5455The implementation of U-Boot is complicated by the fact that U-Boot
5456starts running out of ROM (flash memory), usually without access to
5457system RAM (because the memory controller is not initialized yet).
5458This means that we don't have writable Data or BSS segments, and BSS
5459is not initialized as zero. To be able to get a C environment working
5460at all, we have to allocate at least a minimal stack. Implementation
5461options for this are defined and restricted by the CPU used: Some CPU
5462models provide on-chip memory (like the IMMR area on MPC8xx and
5463MPC826x processors), on others (parts of) the data cache can be
5464locked as (mis-) used as memory, etc.
5465
5466	Chris Hallinan posted a good summary of these issues to the
5467	U-Boot mailing list:
5468
5469	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
5470	From: "Chris Hallinan" <clh@net1plus.com>
5471	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
5472	...
5473
5474	Correct me if I'm wrong, folks, but the way I understand it
5475	is this: Using DCACHE as initial RAM for Stack, etc, does not
5476	require any physical RAM backing up the cache. The cleverness
5477	is that the cache is being used as a temporary supply of
5478	necessary storage before the SDRAM controller is setup. It's
5479	beyond the scope of this list to explain the details, but you
5480	can see how this works by studying the cache architecture and
5481	operation in the architecture and processor-specific manuals.
5482
5483	OCM is On Chip Memory, which I believe the 405GP has 4K. It
5484	is another option for the system designer to use as an
5485	initial stack/RAM area prior to SDRAM being available. Either
5486	option should work for you. Using CS 4 should be fine if your
5487	board designers haven't used it for something that would
5488	cause you grief during the initial boot! It is frequently not
5489	used.
5490
5491	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
5492	with your processor/board/system design. The default value
5493	you will find in any recent u-boot distribution in
5494	walnut.h should work for you. I'd set it to a value larger
5495	than your SDRAM module. If you have a 64MB SDRAM module, set
5496	it above 400_0000. Just make sure your board has no resources
5497	that are supposed to respond to that address! That code in
5498	start.S has been around a while and should work as is when
5499	you get the config right.
5500
5501	-Chris Hallinan
5502	DS4.COM, Inc.
5503
5504It is essential to remember this, since it has some impact on the C
5505code for the initialization procedures:
5506
5507* Initialized global data (data segment) is read-only. Do not attempt
5508  to write it.
5509
5510* Do not use any uninitialized global data (or implicitely initialized
5511  as zero data - BSS segment) at all - this is undefined, initiali-
5512  zation is performed later (when relocating to RAM).
5513
5514* Stack space is very limited. Avoid big data buffers or things like
5515  that.
5516
5517Having only the stack as writable memory limits means we cannot use
5518normal global data to share information beween the code. But it
5519turned out that the implementation of U-Boot can be greatly
5520simplified by making a global data structure (gd_t) available to all
5521functions. We could pass a pointer to this data as argument to _all_
5522functions, but this would bloat the code. Instead we use a feature of
5523the GCC compiler (Global Register Variables) to share the data: we
5524place a pointer (gd) to the global data into a register which we
5525reserve for this purpose.
5526
5527When choosing a register for such a purpose we are restricted by the
5528relevant  (E)ABI  specifications for the current architecture, and by
5529GCC's implementation.
5530
5531For PowerPC, the following registers have specific use:
5532	R1:	stack pointer
5533	R2:	reserved for system use
5534	R3-R4:	parameter passing and return values
5535	R5-R10: parameter passing
5536	R13:	small data area pointer
5537	R30:	GOT pointer
5538	R31:	frame pointer
5539
5540	(U-Boot also uses R12 as internal GOT pointer. r12
5541	is a volatile register so r12 needs to be reset when
5542	going back and forth between asm and C)
5543
5544    ==> U-Boot will use R2 to hold a pointer to the global data
5545
5546    Note: on PPC, we could use a static initializer (since the
5547    address of the global data structure is known at compile time),
5548    but it turned out that reserving a register results in somewhat
5549    smaller code - although the code savings are not that big (on
5550    average for all boards 752 bytes for the whole U-Boot image,
5551    624 text + 127 data).
5552
5553On Blackfin, the normal C ABI (except for P3) is followed as documented here:
5554	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
5555
5556    ==> U-Boot will use P3 to hold a pointer to the global data
5557
5558On ARM, the following registers are used:
5559
5560	R0:	function argument word/integer result
5561	R1-R3:	function argument word
5562	R9:	GOT pointer
5563	R10:	stack limit (used only if stack checking if enabled)
5564	R11:	argument (frame) pointer
5565	R12:	temporary workspace
5566	R13:	stack pointer
5567	R14:	link register
5568	R15:	program counter
5569
5570    ==> U-Boot will use R8 to hold a pointer to the global data
5571
5572On Nios II, the ABI is documented here:
5573	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
5574
5575    ==> U-Boot will use gp to hold a pointer to the global data
5576
5577    Note: on Nios II, we give "-G0" option to gcc and don't use gp
5578    to access small data sections, so gp is free.
5579
5580On NDS32, the following registers are used:
5581
5582	R0-R1:	argument/return
5583	R2-R5:	argument
5584	R15:	temporary register for assembler
5585	R16:	trampoline register
5586	R28:	frame pointer (FP)
5587	R29:	global pointer (GP)
5588	R30:	link register (LP)
5589	R31:	stack pointer (SP)
5590	PC:	program counter (PC)
5591
5592    ==> U-Boot will use R10 to hold a pointer to the global data
5593
5594NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
5595or current versions of GCC may "optimize" the code too much.
5596
5597Memory Management:
5598------------------
5599
5600U-Boot runs in system state and uses physical addresses, i.e. the
5601MMU is not used either for address mapping nor for memory protection.
5602
5603The available memory is mapped to fixed addresses using the memory
5604controller. In this process, a contiguous block is formed for each
5605memory type (Flash, SDRAM, SRAM), even when it consists of several
5606physical memory banks.
5607
5608U-Boot is installed in the first 128 kB of the first Flash bank (on
5609TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
5610booting and sizing and initializing DRAM, the code relocates itself
5611to the upper end of DRAM. Immediately below the U-Boot code some
5612memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
5613configuration setting]. Below that, a structure with global Board
5614Info data is placed, followed by the stack (growing downward).
5615
5616Additionally, some exception handler code is copied to the low 8 kB
5617of DRAM (0x00000000 ... 0x00001FFF).
5618
5619So a typical memory configuration with 16 MB of DRAM could look like
5620this:
5621
5622	0x0000 0000	Exception Vector code
5623	      :
5624	0x0000 1FFF
5625	0x0000 2000	Free for Application Use
5626	      :
5627	      :
5628
5629	      :
5630	      :
5631	0x00FB FF20	Monitor Stack (Growing downward)
5632	0x00FB FFAC	Board Info Data and permanent copy of global data
5633	0x00FC 0000	Malloc Arena
5634	      :
5635	0x00FD FFFF
5636	0x00FE 0000	RAM Copy of Monitor Code
5637	...		eventually: LCD or video framebuffer
5638	...		eventually: pRAM (Protected RAM - unchanged by reset)
5639	0x00FF FFFF	[End of RAM]
5640
5641
5642System Initialization:
5643----------------------
5644
5645In the reset configuration, U-Boot starts at the reset entry point
5646(on most PowerPC systems at address 0x00000100). Because of the reset
5647configuration for CS0# this is a mirror of the onboard Flash memory.
5648To be able to re-map memory U-Boot then jumps to its link address.
5649To be able to implement the initialization code in C, a (small!)
5650initial stack is set up in the internal Dual Ported RAM (in case CPUs
5651which provide such a feature like MPC8xx or MPC8260), or in a locked
5652part of the data cache. After that, U-Boot initializes the CPU core,
5653the caches and the SIU.
5654
5655Next, all (potentially) available memory banks are mapped using a
5656preliminary mapping. For example, we put them on 512 MB boundaries
5657(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
5658on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
5659programmed for SDRAM access. Using the temporary configuration, a
5660simple memory test is run that determines the size of the SDRAM
5661banks.
5662
5663When there is more than one SDRAM bank, and the banks are of
5664different size, the largest is mapped first. For equal size, the first
5665bank (CS2#) is mapped first. The first mapping is always for address
56660x00000000, with any additional banks following immediately to create
5667contiguous memory starting from 0.
5668
5669Then, the monitor installs itself at the upper end of the SDRAM area
5670and allocates memory for use by malloc() and for the global Board
5671Info data; also, the exception vector code is copied to the low RAM
5672pages, and the final stack is set up.
5673
5674Only after this relocation will you have a "normal" C environment;
5675until that you are restricted in several ways, mostly because you are
5676running from ROM, and because the code will have to be relocated to a
5677new address in RAM.
5678
5679
5680U-Boot Porting Guide:
5681----------------------
5682
5683[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
5684list, October 2002]
5685
5686
5687int main(int argc, char *argv[])
5688{
5689	sighandler_t no_more_time;
5690
5691	signal(SIGALRM, no_more_time);
5692	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
5693
5694	if (available_money > available_manpower) {
5695		Pay consultant to port U-Boot;
5696		return 0;
5697	}
5698
5699	Download latest U-Boot source;
5700
5701	Subscribe to u-boot mailing list;
5702
5703	if (clueless)
5704		email("Hi, I am new to U-Boot, how do I get started?");
5705
5706	while (learning) {
5707		Read the README file in the top level directory;
5708		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
5709		Read applicable doc/*.README;
5710		Read the source, Luke;
5711		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
5712	}
5713
5714	if (available_money > toLocalCurrency ($2500))
5715		Buy a BDI3000;
5716	else
5717		Add a lot of aggravation and time;
5718
5719	if (a similar board exists) {	/* hopefully... */
5720		cp -a board/<similar> board/<myboard>
5721		cp include/configs/<similar>.h include/configs/<myboard>.h
5722	} else {
5723		Create your own board support subdirectory;
5724		Create your own board include/configs/<myboard>.h file;
5725	}
5726	Edit new board/<myboard> files
5727	Edit new include/configs/<myboard>.h
5728
5729	while (!accepted) {
5730		while (!running) {
5731			do {
5732				Add / modify source code;
5733			} until (compiles);
5734			Debug;
5735			if (clueless)
5736				email("Hi, I am having problems...");
5737		}
5738		Send patch file to the U-Boot email list;
5739		if (reasonable critiques)
5740			Incorporate improvements from email list code review;
5741		else
5742			Defend code as written;
5743	}
5744
5745	return 0;
5746}
5747
5748void no_more_time (int sig)
5749{
5750      hire_a_guru();
5751}
5752
5753
5754Coding Standards:
5755-----------------
5756
5757All contributions to U-Boot should conform to the Linux kernel
5758coding style; see the file "Documentation/CodingStyle" and the script
5759"scripts/Lindent" in your Linux kernel source directory.
5760
5761Source files originating from a different project (for example the
5762MTD subsystem) are generally exempt from these guidelines and are not
5763reformated to ease subsequent migration to newer versions of those
5764sources.
5765
5766Please note that U-Boot is implemented in C (and to some small parts in
5767Assembler); no C++ is used, so please do not use C++ style comments (//)
5768in your code.
5769
5770Please also stick to the following formatting rules:
5771- remove any trailing white space
5772- use TAB characters for indentation and vertical alignment, not spaces
5773- make sure NOT to use DOS '\r\n' line feeds
5774- do not add more than 2 consecutive empty lines to source files
5775- do not add trailing empty lines to source files
5776
5777Submissions which do not conform to the standards may be returned
5778with a request to reformat the changes.
5779
5780
5781Submitting Patches:
5782-------------------
5783
5784Since the number of patches for U-Boot is growing, we need to
5785establish some rules. Submissions which do not conform to these rules
5786may be rejected, even when they contain important and valuable stuff.
5787
5788Please see http://www.denx.de/wiki/U-Boot/Patches for details.
5789
5790Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
5791see http://lists.denx.de/mailman/listinfo/u-boot
5792
5793When you send a patch, please include the following information with
5794it:
5795
5796* For bug fixes: a description of the bug and how your patch fixes
5797  this bug. Please try to include a way of demonstrating that the
5798  patch actually fixes something.
5799
5800* For new features: a description of the feature and your
5801  implementation.
5802
5803* A CHANGELOG entry as plaintext (separate from the patch)
5804
5805* For major contributions, your entry to the CREDITS file
5806
5807* When you add support for a new board, don't forget to add this
5808  board to the MAINTAINERS file, too.
5809
5810* If your patch adds new configuration options, don't forget to
5811  document these in the README file.
5812
5813* The patch itself. If you are using git (which is *strongly*
5814  recommended) you can easily generate the patch using the
5815  "git format-patch". If you then use "git send-email" to send it to
5816  the U-Boot mailing list, you will avoid most of the common problems
5817  with some other mail clients.
5818
5819  If you cannot use git, use "diff -purN OLD NEW". If your version of
5820  diff does not support these options, then get the latest version of
5821  GNU diff.
5822
5823  The current directory when running this command shall be the parent
5824  directory of the U-Boot source tree (i. e. please make sure that
5825  your patch includes sufficient directory information for the
5826  affected files).
5827
5828  We prefer patches as plain text. MIME attachments are discouraged,
5829  and compressed attachments must not be used.
5830
5831* If one logical set of modifications affects or creates several
5832  files, all these changes shall be submitted in a SINGLE patch file.
5833
5834* Changesets that contain different, unrelated modifications shall be
5835  submitted as SEPARATE patches, one patch per changeset.
5836
5837
5838Notes:
5839
5840* Before sending the patch, run the MAKEALL script on your patched
5841  source tree and make sure that no errors or warnings are reported
5842  for any of the boards.
5843
5844* Keep your modifications to the necessary minimum: A patch
5845  containing several unrelated changes or arbitrary reformats will be
5846  returned with a request to re-formatting / split it.
5847
5848* If you modify existing code, make sure that your new code does not
5849  add to the memory footprint of the code ;-) Small is beautiful!
5850  When adding new features, these should compile conditionally only
5851  (using #ifdef), and the resulting code with the new feature
5852  disabled must not need more memory than the old code without your
5853  modification.
5854
5855* Remember that there is a size limit of 100 kB per message on the
5856  u-boot mailing list. Bigger patches will be moderated. If they are
5857  reasonable and not too big, they will be acknowledged. But patches
5858  bigger than the size limit should be avoided.
5859