xref: /rk3399_rockchip-uboot/README (revision 2c00e099fe77b014dd094a49113e2c6ce8a24a16)
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
57
58Where to get help:
59==================
60
61In case you have questions about, problems with or contributions for
62U-Boot you should send a message to the U-Boot mailing list at
63<u-boot@lists.denx.de>. There is also an archive of previous traffic
64on the mailing list - please search the archive before asking FAQ's.
65Please see http://lists.denx.de/pipermail/u-boot and
66http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
67
68
69Where to get source code:
70=========================
71
72The U-Boot source code is maintained in the git repository at
73git://www.denx.de/git/u-boot.git ; you can browse it online at
74http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
75
76The "snapshot" links on this page allow you to download tarballs of
77any version you might be interested in. Official releases are also
78available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
79directory.
80
81Pre-built (and tested) images are available from
82ftp://ftp.denx.de/pub/u-boot/images/
83
84
85Where we come from:
86===================
87
88- start from 8xxrom sources
89- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
90- clean up code
91- make it easier to add custom boards
92- make it possible to add other [PowerPC] CPUs
93- extend functions, especially:
94  * Provide extended interface to Linux boot loader
95  * S-Record download
96  * network boot
97  * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98- create ARMBoot project (http://sourceforge.net/projects/armboot)
99- add other CPU families (starting with ARM)
100- create U-Boot project (http://sourceforge.net/projects/u-boot)
101- current project page: see http://www.denx.de/wiki/U-Boot
102
103
104Names and Spelling:
105===================
106
107The "official" name of this project is "Das U-Boot". The spelling
108"U-Boot" shall be used in all written text (documentation, comments
109in source files etc.). Example:
110
111	This is the README file for the U-Boot project.
112
113File names etc. shall be based on the string "u-boot". Examples:
114
115	include/asm-ppc/u-boot.h
116
117	#include <asm/u-boot.h>
118
119Variable names, preprocessor constants etc. shall be either based on
120the string "u_boot" or on "U_BOOT". Example:
121
122	U_BOOT_VERSION		u_boot_logo
123	IH_OS_U_BOOT		u_boot_hush_start
124
125
126Versioning:
127===========
128
129Starting with the release in October 2008, the names of the releases
130were changed from numerical release numbers without deeper meaning
131into a time stamp based numbering. Regular releases are identified by
132names consisting of the calendar year and month of the release date.
133Additional fields (if present) indicate release candidates or bug fix
134releases in "stable" maintenance trees.
135
136Examples:
137	U-Boot v2009.11	    - Release November 2009
138	U-Boot v2009.11.1   - Release 1 in version November 2009 stable tree
139	U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release
140
141
142Directory Hierarchy:
143====================
144
145/arch			Architecture specific files
146  /arm			Files generic to ARM architecture
147    /cpu		CPU specific files
148      /arm720t		Files specific to ARM 720 CPUs
149      /arm920t		Files specific to ARM 920 CPUs
150	/at91		Files specific to Atmel AT91RM9200 CPU
151	/imx		Files specific to Freescale MC9328 i.MX CPUs
152	/s3c24x0	Files specific to Samsung S3C24X0 CPUs
153      /arm925t		Files specific to ARM 925 CPUs
154      /arm926ejs	Files specific to ARM 926 CPUs
155      /arm1136		Files specific to ARM 1136 CPUs
156      /ixp		Files specific to Intel XScale IXP CPUs
157      /pxa		Files specific to Intel XScale PXA CPUs
158      /s3c44b0		Files specific to Samsung S3C44B0 CPUs
159      /sa1100		Files specific to Intel StrongARM SA1100 CPUs
160    /lib		Architecture specific library files
161  /avr32		Files generic to AVR32 architecture
162    /cpu		CPU specific files
163    /lib		Architecture specific library files
164  /blackfin		Files generic to Analog Devices Blackfin architecture
165    /cpu		CPU specific files
166    /lib		Architecture specific library files
167  /x86			Files generic to x86 architecture
168    /cpu		CPU specific files
169    /lib		Architecture specific library files
170  /m68k			Files generic to m68k architecture
171    /cpu		CPU specific files
172      /mcf52x2		Files specific to Freescale ColdFire MCF52x2 CPUs
173      /mcf5227x		Files specific to Freescale ColdFire MCF5227x CPUs
174      /mcf532x		Files specific to Freescale ColdFire MCF5329 CPUs
175      /mcf5445x		Files specific to Freescale ColdFire MCF5445x CPUs
176      /mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
177    /lib		Architecture specific library files
178  /microblaze		Files generic to microblaze architecture
179    /cpu		CPU specific files
180    /lib		Architecture specific library files
181  /mips			Files generic to MIPS architecture
182    /cpu		CPU specific files
183      /mips32		Files specific to MIPS32 CPUs
184      /xburst		Files specific to Ingenic XBurst CPUs
185    /lib		Architecture specific library files
186  /nds32		Files generic to NDS32 architecture
187    /cpu		CPU specific files
188      /n1213		Files specific to Andes Technology N1213 CPUs
189    /lib		Architecture specific library files
190  /nios2		Files generic to Altera NIOS2 architecture
191    /cpu		CPU specific files
192    /lib		Architecture specific library files
193  /powerpc		Files generic to PowerPC architecture
194    /cpu		CPU specific files
195      /74xx_7xx		Files specific to Freescale MPC74xx and 7xx CPUs
196      /mpc5xx		Files specific to Freescale MPC5xx CPUs
197      /mpc5xxx		Files specific to Freescale MPC5xxx CPUs
198      /mpc8xx		Files specific to Freescale MPC8xx CPUs
199      /mpc8220		Files specific to Freescale MPC8220 CPUs
200      /mpc824x		Files specific to Freescale MPC824x CPUs
201      /mpc8260		Files specific to Freescale MPC8260 CPUs
202      /mpc85xx		Files specific to Freescale MPC85xx CPUs
203      /ppc4xx		Files specific to AMCC PowerPC 4xx CPUs
204    /lib		Architecture specific library files
205  /sh			Files generic to SH architecture
206    /cpu		CPU specific files
207      /sh2		Files specific to sh2 CPUs
208      /sh3		Files specific to sh3 CPUs
209      /sh4		Files specific to sh4 CPUs
210    /lib		Architecture specific library files
211  /sparc		Files generic to SPARC architecture
212    /cpu		CPU specific files
213      /leon2		Files specific to Gaisler LEON2 SPARC CPU
214      /leon3		Files specific to Gaisler LEON3 SPARC CPU
215    /lib		Architecture specific library files
216/api			Machine/arch independent API for external apps
217/board			Board dependent files
218/common			Misc architecture independent functions
219/disk			Code for disk drive partition handling
220/doc			Documentation (don't expect too much)
221/drivers		Commonly used device drivers
222/examples		Example code for standalone applications, etc.
223/fs			Filesystem code (cramfs, ext2, jffs2, etc.)
224/include		Header Files
225/lib			Files generic to all architectures
226  /libfdt		Library files to support flattened device trees
227  /lzma			Library files to support LZMA decompression
228  /lzo			Library files to support LZO decompression
229/net			Networking code
230/post			Power On Self Test
231/rtc			Real Time Clock drivers
232/tools			Tools to build S-Record or U-Boot images, etc.
233
234Software Configuration:
235=======================
236
237Configuration is usually done using C preprocessor defines; the
238rationale behind that is to avoid dead code whenever possible.
239
240There are two classes of configuration variables:
241
242* Configuration _OPTIONS_:
243  These are selectable by the user and have names beginning with
244  "CONFIG_".
245
246* Configuration _SETTINGS_:
247  These depend on the hardware etc. and should not be meddled with if
248  you don't know what you're doing; they have names beginning with
249  "CONFIG_SYS_".
250
251Later we will add a configuration tool - probably similar to or even
252identical to what's used for the Linux kernel. Right now, we have to
253do the configuration by hand, which means creating some symbolic
254links and editing some configuration files. We use the TQM8xxL boards
255as an example here.
256
257
258Selection of Processor Architecture and Board Type:
259---------------------------------------------------
260
261For all supported boards there are ready-to-use default
262configurations available; just type "make <board_name>_config".
263
264Example: For a TQM823L module type:
265
266	cd u-boot
267	make TQM823L_config
268
269For the Cogent platform, you need to specify the CPU type as well;
270e.g. "make cogent_mpc8xx_config". And also configure the cogent
271directory according to the instructions in cogent/README.
272
273
274Configuration Options:
275----------------------
276
277Configuration depends on the combination of board and CPU type; all
278such information is kept in a configuration file
279"include/configs/<board_name>.h".
280
281Example: For a TQM823L module, all configuration settings are in
282"include/configs/TQM823L.h".
283
284
285Many of the options are named exactly as the corresponding Linux
286kernel configuration options. The intention is to make it easier to
287build a config tool - later.
288
289
290The following options need to be configured:
291
292- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
293
294- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
295
296- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
297		Define exactly one, e.g. CONFIG_ATSTK1002
298
299- CPU Module Type: (if CONFIG_COGENT is defined)
300		Define exactly one of
301		CONFIG_CMA286_60_OLD
302--- FIXME --- not tested yet:
303		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
304		CONFIG_CMA287_23, CONFIG_CMA287_50
305
306- Motherboard Type: (if CONFIG_COGENT is defined)
307		Define exactly one of
308		CONFIG_CMA101, CONFIG_CMA102
309
310- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
311		Define one or more of
312		CONFIG_CMA302
313
314- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
315		Define one or more of
316		CONFIG_LCD_HEARTBEAT	- update a character position on
317					  the LCD display every second with
318					  a "rotator" |\-/|\-/
319
320- Board flavour: (if CONFIG_MPC8260ADS is defined)
321		CONFIG_ADSTYPE
322		Possible values are:
323			CONFIG_SYS_8260ADS	- original MPC8260ADS
324			CONFIG_SYS_8266ADS	- MPC8266ADS
325			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
326			CONFIG_SYS_8272ADS	- MPC8272ADS
327
328- Marvell Family Member
329		CONFIG_SYS_MVFS		- define it if you want to enable
330					  multiple fs option at one time
331					  for marvell soc family
332
333- MPC824X Family Member (if CONFIG_MPC824X is defined)
334		Define exactly one of
335		CONFIG_MPC8240, CONFIG_MPC8245
336
337- 8xx CPU Options: (if using an MPC8xx CPU)
338		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
339					  get_gclk_freq() cannot work
340					  e.g. if there is no 32KHz
341					  reference PIT/RTC clock
342		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
343					  or XTAL/EXTAL)
344
345- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
346		CONFIG_SYS_8xx_CPUCLK_MIN
347		CONFIG_SYS_8xx_CPUCLK_MAX
348		CONFIG_8xx_CPUCLK_DEFAULT
349			See doc/README.MPC866
350
351		CONFIG_SYS_MEASURE_CPUCLK
352
353		Define this to measure the actual CPU clock instead
354		of relying on the correctness of the configured
355		values. Mostly useful for board bringup to make sure
356		the PLL is locked at the intended frequency. Note
357		that this requires a (stable) reference clock (32 kHz
358		RTC clock or CONFIG_SYS_8XX_XIN)
359
360		CONFIG_SYS_DELAYED_ICACHE
361
362		Define this option if you want to enable the
363		ICache only when Code runs from RAM.
364
365- 85xx CPU Options:
366		CONFIG_SYS_FSL_TBCLK_DIV
367
368		Defines the core time base clock divider ratio compared to the
369		system clock.  On most PQ3 devices this is 8, on newer QorIQ
370		devices it can be 16 or 32.  The ratio varies from SoC to Soc.
371
372		CONFIG_SYS_FSL_PCIE_COMPAT
373
374		Defines the string to utilize when trying to match PCIe device
375		tree nodes for the given platform.
376
377- Generic CPU options:
378		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
379
380		Defines the endianess of the CPU. Implementation of those
381		values is arch specific.
382
383- Intel Monahans options:
384		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
385
386		Defines the Monahans run mode to oscillator
387		ratio. Valid values are 8, 16, 24, 31. The core
388		frequency is this value multiplied by 13 MHz.
389
390		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
391
392		Defines the Monahans turbo mode to oscillator
393		ratio. Valid values are 1 (default if undefined) and
394		2. The core frequency as calculated above is multiplied
395		by this value.
396
397- MIPS CPU options:
398		CONFIG_SYS_INIT_SP_OFFSET
399
400		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
401		pointer. This is needed for the temporary stack before
402		relocation.
403
404		CONFIG_SYS_MIPS_CACHE_MODE
405
406		Cache operation mode for the MIPS CPU.
407		See also arch/mips/include/asm/mipsregs.h.
408		Possible values are:
409			CONF_CM_CACHABLE_NO_WA
410			CONF_CM_CACHABLE_WA
411			CONF_CM_UNCACHED
412			CONF_CM_CACHABLE_NONCOHERENT
413			CONF_CM_CACHABLE_CE
414			CONF_CM_CACHABLE_COW
415			CONF_CM_CACHABLE_CUW
416			CONF_CM_CACHABLE_ACCELERATED
417
418		CONFIG_SYS_XWAY_EBU_BOOTCFG
419
420		Special option for Lantiq XWAY SoCs for booting from NOR flash.
421		See also arch/mips/cpu/mips32/start.S.
422
423		CONFIG_XWAY_SWAP_BYTES
424
425		Enable compilation of tools/xway-swap-bytes needed for Lantiq
426		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
427		be swapped if a flash programmer is used.
428
429- ARM options:
430		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
431
432		Select high exception vectors of the ARM core, e.g., do not
433		clear the V bit of the c1 register of CP15.
434
435		CONFIG_SYS_THUMB_BUILD
436
437		Use this flag to build U-Boot using the Thumb instruction
438		set for ARM architectures. Thumb instruction set provides
439		better code density. For ARM architectures that support
440		Thumb2 this flag will result in Thumb2 code generated by
441		GCC.
442
443- Linux Kernel Interface:
444		CONFIG_CLOCKS_IN_MHZ
445
446		U-Boot stores all clock information in Hz
447		internally. For binary compatibility with older Linux
448		kernels (which expect the clocks passed in the
449		bd_info data to be in MHz) the environment variable
450		"clocks_in_mhz" can be defined so that U-Boot
451		converts clock data to MHZ before passing it to the
452		Linux kernel.
453		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
454		"clocks_in_mhz=1" is automatically included in the
455		default environment.
456
457		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
458
459		When transferring memsize parameter to linux, some versions
460		expect it to be in bytes, others in MB.
461		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
462
463		CONFIG_OF_LIBFDT
464
465		New kernel versions are expecting firmware settings to be
466		passed using flattened device trees (based on open firmware
467		concepts).
468
469		CONFIG_OF_LIBFDT
470		 * New libfdt-based support
471		 * Adds the "fdt" command
472		 * The bootm command automatically updates the fdt
473
474		OF_CPU - The proper name of the cpus node (only required for
475			MPC512X and MPC5xxx based boards).
476		OF_SOC - The proper name of the soc node (only required for
477			MPC512X and MPC5xxx based boards).
478		OF_TBCLK - The timebase frequency.
479		OF_STDOUT_PATH - The path to the console device
480
481		boards with QUICC Engines require OF_QE to set UCC MAC
482		addresses
483
484		CONFIG_OF_BOARD_SETUP
485
486		Board code has addition modification that it wants to make
487		to the flat device tree before handing it off to the kernel
488
489		CONFIG_OF_BOOT_CPU
490
491		This define fills in the correct boot CPU in the boot
492		param header, the default value is zero if undefined.
493
494		CONFIG_OF_IDE_FIXUP
495
496		U-Boot can detect if an IDE device is present or not.
497		If not, and this new config option is activated, U-Boot
498		removes the ATA node from the DTS before booting Linux,
499		so the Linux IDE driver does not probe the device and
500		crash. This is needed for buggy hardware (uc101) where
501		no pull down resistor is connected to the signal IDE5V_DD7.
502
503		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
504
505		This setting is mandatory for all boards that have only one
506		machine type and must be used to specify the machine type
507		number as it appears in the ARM machine registry
508		(see http://www.arm.linux.org.uk/developer/machines/).
509		Only boards that have multiple machine types supported
510		in a single configuration file and the machine type is
511		runtime discoverable, do not have to use this setting.
512
513- vxWorks boot parameters:
514
515		bootvx constructs a valid bootline using the following
516		environments variables: bootfile, ipaddr, serverip, hostname.
517		It loads the vxWorks image pointed bootfile.
518
519		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
520		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
521		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
522		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
523
524		CONFIG_SYS_VXWORKS_ADD_PARAMS
525
526		Add it at the end of the bootline. E.g "u=username pw=secret"
527
528		Note: If a "bootargs" environment is defined, it will overwride
529		the defaults discussed just above.
530
531- Cache Configuration:
532		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
533		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
534		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
535
536- Cache Configuration for ARM:
537		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
538				      controller
539		CONFIG_SYS_PL310_BASE - Physical base address of PL310
540					controller register space
541
542- Serial Ports:
543		CONFIG_PL010_SERIAL
544
545		Define this if you want support for Amba PrimeCell PL010 UARTs.
546
547		CONFIG_PL011_SERIAL
548
549		Define this if you want support for Amba PrimeCell PL011 UARTs.
550
551		CONFIG_PL011_CLOCK
552
553		If you have Amba PrimeCell PL011 UARTs, set this variable to
554		the clock speed of the UARTs.
555
556		CONFIG_PL01x_PORTS
557
558		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
559		define this to a list of base addresses for each (supported)
560		port. See e.g. include/configs/versatile.h
561
562		CONFIG_PL011_SERIAL_RLCR
563
564		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
565		have separate receive and transmit line control registers.  Set
566		this variable to initialize the extra register.
567
568		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
569
570		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
571		boot loader that has already initialized the UART.  Define this
572		variable to flush the UART at init time.
573
574
575- Console Interface:
576		Depending on board, define exactly one serial port
577		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
578		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
579		console by defining CONFIG_8xx_CONS_NONE
580
581		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
582		port routines must be defined elsewhere
583		(i.e. serial_init(), serial_getc(), ...)
584
585		CONFIG_CFB_CONSOLE
586		Enables console device for a color framebuffer. Needs following
587		defines (cf. smiLynxEM, i8042)
588			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
589						(default big endian)
590			VIDEO_HW_RECTFILL	graphic chip supports
591						rectangle fill
592						(cf. smiLynxEM)
593			VIDEO_HW_BITBLT		graphic chip supports
594						bit-blit (cf. smiLynxEM)
595			VIDEO_VISIBLE_COLS	visible pixel columns
596						(cols=pitch)
597			VIDEO_VISIBLE_ROWS	visible pixel rows
598			VIDEO_PIXEL_SIZE	bytes per pixel
599			VIDEO_DATA_FORMAT	graphic data format
600						(0-5, cf. cfb_console.c)
601			VIDEO_FB_ADRS		framebuffer address
602			VIDEO_KBD_INIT_FCT	keyboard int fct
603						(i.e. i8042_kbd_init())
604			VIDEO_TSTC_FCT		test char fct
605						(i.e. i8042_tstc)
606			VIDEO_GETC_FCT		get char fct
607						(i.e. i8042_getc)
608			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
609						(requires blink timer
610						cf. i8042.c)
611			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
612			CONFIG_CONSOLE_TIME	display time/date info in
613						upper right corner
614						(requires CONFIG_CMD_DATE)
615			CONFIG_VIDEO_LOGO	display Linux logo in
616						upper left corner
617			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
618						linux_logo.h for logo.
619						Requires CONFIG_VIDEO_LOGO
620			CONFIG_CONSOLE_EXTRA_INFO
621						additional board info beside
622						the logo
623
624		When CONFIG_CFB_CONSOLE is defined, video console is
625		default i/o. Serial console can be forced with
626		environment 'console=serial'.
627
628		When CONFIG_SILENT_CONSOLE is defined, all console
629		messages (by U-Boot and Linux!) can be silenced with
630		the "silent" environment variable. See
631		doc/README.silent for more information.
632
633- Console Baudrate:
634		CONFIG_BAUDRATE - in bps
635		Select one of the baudrates listed in
636		CONFIG_SYS_BAUDRATE_TABLE, see below.
637		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
638
639- Console Rx buffer length
640		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
641		the maximum receive buffer length for the SMC.
642		This option is actual only for 82xx and 8xx possible.
643		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
644		must be defined, to setup the maximum idle timeout for
645		the SMC.
646
647- Pre-Console Buffer:
648		Prior to the console being initialised (i.e. serial UART
649		initialised etc) all console output is silently discarded.
650		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
651		buffer any console messages prior to the console being
652		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
653		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
654		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
655		bytes are output before the console is initialised, the
656		earlier bytes are discarded.
657
658		'Sane' compilers will generate smaller code if
659		CONFIG_PRE_CON_BUF_SZ is a power of 2
660
661- Safe printf() functions
662		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
663		the printf() functions. These are defined in
664		include/vsprintf.h and include snprintf(), vsnprintf() and
665		so on. Code size increase is approximately 300-500 bytes.
666		If this option is not given then these functions will
667		silently discard their buffer size argument - this means
668		you are not getting any overflow checking in this case.
669
670- Boot Delay:	CONFIG_BOOTDELAY - in seconds
671		Delay before automatically booting the default image;
672		set to -1 to disable autoboot.
673
674		See doc/README.autoboot for these options that
675		work with CONFIG_BOOTDELAY. None are required.
676		CONFIG_BOOT_RETRY_TIME
677		CONFIG_BOOT_RETRY_MIN
678		CONFIG_AUTOBOOT_KEYED
679		CONFIG_AUTOBOOT_PROMPT
680		CONFIG_AUTOBOOT_DELAY_STR
681		CONFIG_AUTOBOOT_STOP_STR
682		CONFIG_AUTOBOOT_DELAY_STR2
683		CONFIG_AUTOBOOT_STOP_STR2
684		CONFIG_ZERO_BOOTDELAY_CHECK
685		CONFIG_RESET_TO_RETRY
686
687- Autoboot Command:
688		CONFIG_BOOTCOMMAND
689		Only needed when CONFIG_BOOTDELAY is enabled;
690		define a command string that is automatically executed
691		when no character is read on the console interface
692		within "Boot Delay" after reset.
693
694		CONFIG_BOOTARGS
695		This can be used to pass arguments to the bootm
696		command. The value of CONFIG_BOOTARGS goes into the
697		environment value "bootargs".
698
699		CONFIG_RAMBOOT and CONFIG_NFSBOOT
700		The value of these goes into the environment as
701		"ramboot" and "nfsboot" respectively, and can be used
702		as a convenience, when switching between booting from
703		RAM and NFS.
704
705- Pre-Boot Commands:
706		CONFIG_PREBOOT
707
708		When this option is #defined, the existence of the
709		environment variable "preboot" will be checked
710		immediately before starting the CONFIG_BOOTDELAY
711		countdown and/or running the auto-boot command resp.
712		entering interactive mode.
713
714		This feature is especially useful when "preboot" is
715		automatically generated or modified. For an example
716		see the LWMON board specific code: here "preboot" is
717		modified when the user holds down a certain
718		combination of keys on the (special) keyboard when
719		booting the systems
720
721- Serial Download Echo Mode:
722		CONFIG_LOADS_ECHO
723		If defined to 1, all characters received during a
724		serial download (using the "loads" command) are
725		echoed back. This might be needed by some terminal
726		emulations (like "cu"), but may as well just take
727		time on others. This setting #define's the initial
728		value of the "loads_echo" environment variable.
729
730- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
731		CONFIG_KGDB_BAUDRATE
732		Select one of the baudrates listed in
733		CONFIG_SYS_BAUDRATE_TABLE, see below.
734
735- Monitor Functions:
736		Monitor commands can be included or excluded
737		from the build by using the #include files
738		"config_cmd_all.h" and #undef'ing unwanted
739		commands, or using "config_cmd_default.h"
740		and augmenting with additional #define's
741		for wanted commands.
742
743		The default command configuration includes all commands
744		except those marked below with a "*".
745
746		CONFIG_CMD_ASKENV	* ask for env variable
747		CONFIG_CMD_BDI		  bdinfo
748		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
749		CONFIG_CMD_BMP		* BMP support
750		CONFIG_CMD_BSP		* Board specific commands
751		CONFIG_CMD_BOOTD	  bootd
752		CONFIG_CMD_CACHE	* icache, dcache
753		CONFIG_CMD_CONSOLE	  coninfo
754		CONFIG_CMD_CRC32	* crc32
755		CONFIG_CMD_DATE		* support for RTC, date/time...
756		CONFIG_CMD_DHCP		* DHCP support
757		CONFIG_CMD_DIAG		* Diagnostics
758		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
759		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
760		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
761		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
762		CONFIG_CMD_DTT		* Digital Therm and Thermostat
763		CONFIG_CMD_ECHO		  echo arguments
764		CONFIG_CMD_EDITENV	  edit env variable
765		CONFIG_CMD_EEPROM	* EEPROM read/write support
766		CONFIG_CMD_ELF		* bootelf, bootvx
767		CONFIG_CMD_EXPORTENV	* export the environment
768		CONFIG_CMD_SAVEENV	  saveenv
769		CONFIG_CMD_FDC		* Floppy Disk Support
770		CONFIG_CMD_FAT		* FAT partition support
771		CONFIG_CMD_FDOS		* Dos diskette Support
772		CONFIG_CMD_FLASH	  flinfo, erase, protect
773		CONFIG_CMD_FPGA		  FPGA device initialization support
774		CONFIG_CMD_GO		* the 'go' command (exec code)
775		CONFIG_CMD_GREPENV	* search environment
776		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
777		CONFIG_CMD_I2C		* I2C serial bus support
778		CONFIG_CMD_IDE		* IDE harddisk support
779		CONFIG_CMD_IMI		  iminfo
780		CONFIG_CMD_IMLS		  List all found images
781		CONFIG_CMD_IMMAP	* IMMR dump support
782		CONFIG_CMD_IMPORTENV	* import an environment
783		CONFIG_CMD_IRQ		* irqinfo
784		CONFIG_CMD_ITEST	  Integer/string test of 2 values
785		CONFIG_CMD_JFFS2	* JFFS2 Support
786		CONFIG_CMD_KGDB		* kgdb
787		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
788		CONFIG_CMD_LOADB	  loadb
789		CONFIG_CMD_LOADS	  loads
790		CONFIG_CMD_MD5SUM	  print md5 message digest
791					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
792		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
793					  loop, loopw, mtest
794		CONFIG_CMD_MISC		  Misc functions like sleep etc
795		CONFIG_CMD_MMC		* MMC memory mapped support
796		CONFIG_CMD_MII		* MII utility commands
797		CONFIG_CMD_MTDPARTS	* MTD partition support
798		CONFIG_CMD_NAND		* NAND support
799		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
800		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
801		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
802		CONFIG_CMD_PCI		* pciinfo
803		CONFIG_CMD_PCMCIA		* PCMCIA support
804		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
805					  host
806		CONFIG_CMD_PORTIO	* Port I/O
807		CONFIG_CMD_REGINFO	* Register dump
808		CONFIG_CMD_RUN		  run command in env variable
809		CONFIG_CMD_SAVES	* save S record dump
810		CONFIG_CMD_SCSI		* SCSI Support
811		CONFIG_CMD_SDRAM	* print SDRAM configuration information
812					  (requires CONFIG_CMD_I2C)
813		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
814					  (4xx only)
815		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
816		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
817					  (requires CONFIG_CMD_MEMORY)
818		CONFIG_CMD_SOURCE	  "source" command Support
819		CONFIG_CMD_SPI		* SPI serial bus support
820		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
821		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
822		CONFIG_CMD_TIME		* run command and report execution time
823		CONFIG_CMD_USB		* USB support
824		CONFIG_CMD_CDP		* Cisco Discover Protocol support
825		CONFIG_CMD_MFSL		* Microblaze FSL support
826
827
828		EXAMPLE: If you want all functions except of network
829		support you can write:
830
831		#include "config_cmd_all.h"
832		#undef CONFIG_CMD_NET
833
834	Other Commands:
835		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
836
837	Note:	Don't enable the "icache" and "dcache" commands
838		(configuration option CONFIG_CMD_CACHE) unless you know
839		what you (and your U-Boot users) are doing. Data
840		cache cannot be enabled on systems like the 8xx or
841		8260 (where accesses to the IMMR region must be
842		uncached), and it cannot be disabled on all other
843		systems where we (mis-) use the data cache to hold an
844		initial stack and some data.
845
846
847		XXX - this list needs to get updated!
848
849- Device tree:
850		CONFIG_OF_CONTROL
851		If this variable is defined, U-Boot will use a device tree
852		to configure its devices, instead of relying on statically
853		compiled #defines in the board file. This option is
854		experimental and only available on a few boards. The device
855		tree is available in the global data as gd->fdt_blob.
856
857		U-Boot needs to get its device tree from somewhere. This can
858		be done using one of the two options below:
859
860		CONFIG_OF_EMBED
861		If this variable is defined, U-Boot will embed a device tree
862		binary in its image. This device tree file should be in the
863		board directory and called <soc>-<board>.dts. The binary file
864		is then picked up in board_init_f() and made available through
865		the global data structure as gd->blob.
866
867		CONFIG_OF_SEPARATE
868		If this variable is defined, U-Boot will build a device tree
869		binary. It will be called u-boot.dtb. Architecture-specific
870		code will locate it at run-time. Generally this works by:
871
872			cat u-boot.bin u-boot.dtb >image.bin
873
874		and in fact, U-Boot does this for you, creating a file called
875		u-boot-dtb.bin which is useful in the common case. You can
876		still use the individual files if you need something more
877		exotic.
878
879- Watchdog:
880		CONFIG_WATCHDOG
881		If this variable is defined, it enables watchdog
882		support for the SoC. There must be support in the SoC
883		specific code for a watchdog. For the 8xx and 8260
884		CPUs, the SIU Watchdog feature is enabled in the SYPCR
885		register.  When supported for a specific SoC is
886		available, then no further board specific code should
887		be needed to use it.
888
889		CONFIG_HW_WATCHDOG
890		When using a watchdog circuitry external to the used
891		SoC, then define this variable and provide board
892		specific code for the "hw_watchdog_reset" function.
893
894- U-Boot Version:
895		CONFIG_VERSION_VARIABLE
896		If this variable is defined, an environment variable
897		named "ver" is created by U-Boot showing the U-Boot
898		version as printed by the "version" command.
899		This variable is readonly.
900
901- Real-Time Clock:
902
903		When CONFIG_CMD_DATE is selected, the type of the RTC
904		has to be selected, too. Define exactly one of the
905		following options:
906
907		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
908		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
909		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
910		CONFIG_RTC_MC146818	- use MC146818 RTC
911		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
912		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
913		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
914		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
915		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
916		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
917		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
918		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
919					  RV3029 RTC.
920
921		Note that if the RTC uses I2C, then the I2C interface
922		must also be configured. See I2C Support, below.
923
924- GPIO Support:
925		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
926		CONFIG_PCA953X_INFO	- enable pca953x info command
927
928		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
929		chip-ngpio pairs that tell the PCA953X driver the number of
930		pins supported by a particular chip.
931
932		Note that if the GPIO device uses I2C, then the I2C interface
933		must also be configured. See I2C Support, below.
934
935- Timestamp Support:
936
937		When CONFIG_TIMESTAMP is selected, the timestamp
938		(date and time) of an image is printed by image
939		commands like bootm or iminfo. This option is
940		automatically enabled when you select CONFIG_CMD_DATE .
941
942- Partition Support:
943		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
944		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
945
946		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
947		CONFIG_CMD_SCSI) you must configure support for at
948		least one partition type as well.
949
950- IDE Reset method:
951		CONFIG_IDE_RESET_ROUTINE - this is defined in several
952		board configurations files but used nowhere!
953
954		CONFIG_IDE_RESET - is this is defined, IDE Reset will
955		be performed by calling the function
956			ide_set_reset(int reset)
957		which has to be defined in a board specific file
958
959- ATAPI Support:
960		CONFIG_ATAPI
961
962		Set this to enable ATAPI support.
963
964- LBA48 Support
965		CONFIG_LBA48
966
967		Set this to enable support for disks larger than 137GB
968		Also look at CONFIG_SYS_64BIT_LBA.
969		Whithout these , LBA48 support uses 32bit variables and will 'only'
970		support disks up to 2.1TB.
971
972		CONFIG_SYS_64BIT_LBA:
973			When enabled, makes the IDE subsystem use 64bit sector addresses.
974			Default is 32bit.
975
976- SCSI Support:
977		At the moment only there is only support for the
978		SYM53C8XX SCSI controller; define
979		CONFIG_SCSI_SYM53C8XX to enable it.
980
981		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
982		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
983		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
984		maximum numbers of LUNs, SCSI ID's and target
985		devices.
986		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
987
988- NETWORK Support (PCI):
989		CONFIG_E1000
990		Support for Intel 8254x/8257x gigabit chips.
991
992		CONFIG_E1000_SPI
993		Utility code for direct access to the SPI bus on Intel 8257x.
994		This does not do anything useful unless you set at least one
995		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
996
997		CONFIG_E1000_SPI_GENERIC
998		Allow generic access to the SPI bus on the Intel 8257x, for
999		example with the "sspi" command.
1000
1001		CONFIG_CMD_E1000
1002		Management command for E1000 devices.  When used on devices
1003		with SPI support you can reprogram the EEPROM from U-Boot.
1004
1005		CONFIG_E1000_FALLBACK_MAC
1006		default MAC for empty EEPROM after production.
1007
1008		CONFIG_EEPRO100
1009		Support for Intel 82557/82559/82559ER chips.
1010		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
1011		write routine for first time initialisation.
1012
1013		CONFIG_TULIP
1014		Support for Digital 2114x chips.
1015		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1016		modem chip initialisation (KS8761/QS6611).
1017
1018		CONFIG_NATSEMI
1019		Support for National dp83815 chips.
1020
1021		CONFIG_NS8382X
1022		Support for National dp8382[01] gigabit chips.
1023
1024- NETWORK Support (other):
1025
1026		CONFIG_DRIVER_AT91EMAC
1027		Support for AT91RM9200 EMAC.
1028
1029			CONFIG_RMII
1030			Define this to use reduced MII inteface
1031
1032			CONFIG_DRIVER_AT91EMAC_QUIET
1033			If this defined, the driver is quiet.
1034			The driver doen't show link status messages.
1035
1036		CONFIG_CALXEDA_XGMAC
1037		Support for the Calxeda XGMAC device
1038
1039		CONFIG_DRIVER_LAN91C96
1040		Support for SMSC's LAN91C96 chips.
1041
1042			CONFIG_LAN91C96_BASE
1043			Define this to hold the physical address
1044			of the LAN91C96's I/O space
1045
1046			CONFIG_LAN91C96_USE_32_BIT
1047			Define this to enable 32 bit addressing
1048
1049		CONFIG_DRIVER_SMC91111
1050		Support for SMSC's LAN91C111 chip
1051
1052			CONFIG_SMC91111_BASE
1053			Define this to hold the physical address
1054			of the device (I/O space)
1055
1056			CONFIG_SMC_USE_32_BIT
1057			Define this if data bus is 32 bits
1058
1059			CONFIG_SMC_USE_IOFUNCS
1060			Define this to use i/o functions instead of macros
1061			(some hardware wont work with macros)
1062
1063		CONFIG_DRIVER_TI_EMAC
1064		Support for davinci emac
1065
1066			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1067			Define this if you have more then 3 PHYs.
1068
1069		CONFIG_FTGMAC100
1070		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1071
1072			CONFIG_FTGMAC100_EGIGA
1073			Define this to use GE link update with gigabit PHY.
1074			Define this if FTGMAC100 is connected to gigabit PHY.
1075			If your system has 10/100 PHY only, it might not occur
1076			wrong behavior. Because PHY usually return timeout or
1077			useless data when polling gigabit status and gigabit
1078			control registers. This behavior won't affect the
1079			correctnessof 10/100 link speed update.
1080
1081		CONFIG_SMC911X
1082		Support for SMSC's LAN911x and LAN921x chips
1083
1084			CONFIG_SMC911X_BASE
1085			Define this to hold the physical address
1086			of the device (I/O space)
1087
1088			CONFIG_SMC911X_32_BIT
1089			Define this if data bus is 32 bits
1090
1091			CONFIG_SMC911X_16_BIT
1092			Define this if data bus is 16 bits. If your processor
1093			automatically converts one 32 bit word to two 16 bit
1094			words you may also try CONFIG_SMC911X_32_BIT.
1095
1096		CONFIG_SH_ETHER
1097		Support for Renesas on-chip Ethernet controller
1098
1099			CONFIG_SH_ETHER_USE_PORT
1100			Define the number of ports to be used
1101
1102			CONFIG_SH_ETHER_PHY_ADDR
1103			Define the ETH PHY's address
1104
1105			CONFIG_SH_ETHER_CACHE_WRITEBACK
1106			If this option is set, the driver enables cache flush.
1107
1108- TPM Support:
1109		CONFIG_GENERIC_LPC_TPM
1110		Support for generic parallel port TPM devices. Only one device
1111		per system is supported at this time.
1112
1113			CONFIG_TPM_TIS_BASE_ADDRESS
1114			Base address where the generic TPM device is mapped
1115			to. Contemporary x86 systems usually map it at
1116			0xfed40000.
1117
1118- USB Support:
1119		At the moment only the UHCI host controller is
1120		supported (PIP405, MIP405, MPC5200); define
1121		CONFIG_USB_UHCI to enable it.
1122		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1123		and define CONFIG_USB_STORAGE to enable the USB
1124		storage devices.
1125		Note:
1126		Supported are USB Keyboards and USB Floppy drives
1127		(TEAC FD-05PUB).
1128		MPC5200 USB requires additional defines:
1129			CONFIG_USB_CLOCK
1130				for 528 MHz Clock: 0x0001bbbb
1131			CONFIG_PSC3_USB
1132				for USB on PSC3
1133			CONFIG_USB_CONFIG
1134				for differential drivers: 0x00001000
1135				for single ended drivers: 0x00005000
1136				for differential drivers on PSC3: 0x00000100
1137				for single ended drivers on PSC3: 0x00004100
1138			CONFIG_SYS_USB_EVENT_POLL
1139				May be defined to allow interrupt polling
1140				instead of using asynchronous interrupts
1141
1142		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
1143		txfilltuning field in the EHCI controller on reset.
1144
1145- USB Device:
1146		Define the below if you wish to use the USB console.
1147		Once firmware is rebuilt from a serial console issue the
1148		command "setenv stdin usbtty; setenv stdout usbtty" and
1149		attach your USB cable. The Unix command "dmesg" should print
1150		it has found a new device. The environment variable usbtty
1151		can be set to gserial or cdc_acm to enable your device to
1152		appear to a USB host as a Linux gserial device or a
1153		Common Device Class Abstract Control Model serial device.
1154		If you select usbtty = gserial you should be able to enumerate
1155		a Linux host by
1156		# modprobe usbserial vendor=0xVendorID product=0xProductID
1157		else if using cdc_acm, simply setting the environment
1158		variable usbtty to be cdc_acm should suffice. The following
1159		might be defined in YourBoardName.h
1160
1161			CONFIG_USB_DEVICE
1162			Define this to build a UDC device
1163
1164			CONFIG_USB_TTY
1165			Define this to have a tty type of device available to
1166			talk to the UDC device
1167
1168			CONFIG_USBD_HS
1169			Define this to enable the high speed support for usb
1170			device and usbtty. If this feature is enabled, a routine
1171			int is_usbd_high_speed(void)
1172			also needs to be defined by the driver to dynamically poll
1173			whether the enumeration has succeded at high speed or full
1174			speed.
1175
1176			CONFIG_SYS_CONSOLE_IS_IN_ENV
1177			Define this if you want stdin, stdout &/or stderr to
1178			be set to usbtty.
1179
1180			mpc8xx:
1181				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1182				Derive USB clock from external clock "blah"
1183				- CONFIG_SYS_USB_EXTC_CLK 0x02
1184
1185				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1186				Derive USB clock from brgclk
1187				- CONFIG_SYS_USB_BRG_CLK 0x04
1188
1189		If you have a USB-IF assigned VendorID then you may wish to
1190		define your own vendor specific values either in BoardName.h
1191		or directly in usbd_vendor_info.h. If you don't define
1192		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1193		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1194		should pretend to be a Linux device to it's target host.
1195
1196			CONFIG_USBD_MANUFACTURER
1197			Define this string as the name of your company for
1198			- CONFIG_USBD_MANUFACTURER "my company"
1199
1200			CONFIG_USBD_PRODUCT_NAME
1201			Define this string as the name of your product
1202			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1203
1204			CONFIG_USBD_VENDORID
1205			Define this as your assigned Vendor ID from the USB
1206			Implementors Forum. This *must* be a genuine Vendor ID
1207			to avoid polluting the USB namespace.
1208			- CONFIG_USBD_VENDORID 0xFFFF
1209
1210			CONFIG_USBD_PRODUCTID
1211			Define this as the unique Product ID
1212			for your device
1213			- CONFIG_USBD_PRODUCTID 0xFFFF
1214
1215- ULPI Layer Support:
1216		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1217		the generic ULPI layer. The generic layer accesses the ULPI PHY
1218		via the platform viewport, so you need both the genric layer and
1219		the viewport enabled. Currently only Chipidea/ARC based
1220		viewport is supported.
1221		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1222		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1223
1224- MMC Support:
1225		The MMC controller on the Intel PXA is supported. To
1226		enable this define CONFIG_MMC. The MMC can be
1227		accessed from the boot prompt by mapping the device
1228		to physical memory similar to flash. Command line is
1229		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1230		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1231
1232		CONFIG_SH_MMCIF
1233		Support for Renesas on-chip MMCIF controller
1234
1235			CONFIG_SH_MMCIF_ADDR
1236			Define the base address of MMCIF registers
1237
1238			CONFIG_SH_MMCIF_CLK
1239			Define the clock frequency for MMCIF
1240
1241- Journaling Flash filesystem support:
1242		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1243		CONFIG_JFFS2_NAND_DEV
1244		Define these for a default partition on a NAND device
1245
1246		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1247		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1248		Define these for a default partition on a NOR device
1249
1250		CONFIG_SYS_JFFS_CUSTOM_PART
1251		Define this to create an own partition. You have to provide a
1252		function struct part_info* jffs2_part_info(int part_num)
1253
1254		If you define only one JFFS2 partition you may also want to
1255		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1256		to disable the command chpart. This is the default when you
1257		have not defined a custom partition
1258
1259- FAT(File Allocation Table) filesystem write function support:
1260		CONFIG_FAT_WRITE
1261
1262		Define this to enable support for saving memory data as a
1263		file in FAT formatted partition.
1264
1265		This will also enable the command "fatwrite" enabling the
1266		user to write files to FAT.
1267
1268- Keyboard Support:
1269		CONFIG_ISA_KEYBOARD
1270
1271		Define this to enable standard (PC-Style) keyboard
1272		support
1273
1274		CONFIG_I8042_KBD
1275		Standard PC keyboard driver with US (is default) and
1276		GERMAN key layout (switch via environment 'keymap=de') support.
1277		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1278		for cfb_console. Supports cursor blinking.
1279
1280- Video support:
1281		CONFIG_VIDEO
1282
1283		Define this to enable video support (for output to
1284		video).
1285
1286		CONFIG_VIDEO_CT69000
1287
1288		Enable Chips & Technologies 69000 Video chip
1289
1290		CONFIG_VIDEO_SMI_LYNXEM
1291		Enable Silicon Motion SMI 712/710/810 Video chip. The
1292		video output is selected via environment 'videoout'
1293		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1294		assumed.
1295
1296		For the CT69000 and SMI_LYNXEM drivers, videomode is
1297		selected via environment 'videomode'. Two different ways
1298		are possible:
1299		- "videomode=num"   'num' is a standard LiLo mode numbers.
1300		Following standard modes are supported	(* is default):
1301
1302		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1303		-------------+---------------------------------------------
1304		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1305		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1306		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1307		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1308		-------------+---------------------------------------------
1309		(i.e. setenv videomode 317; saveenv; reset;)
1310
1311		- "videomode=bootargs" all the video parameters are parsed
1312		from the bootargs. (See drivers/video/videomodes.c)
1313
1314
1315		CONFIG_VIDEO_SED13806
1316		Enable Epson SED13806 driver. This driver supports 8bpp
1317		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1318		or CONFIG_VIDEO_SED13806_16BPP
1319
1320		CONFIG_FSL_DIU_FB
1321		Enable the Freescale DIU video driver.	Reference boards for
1322		SOCs that have a DIU should define this macro to enable DIU
1323		support, and should also define these other macros:
1324
1325			CONFIG_SYS_DIU_ADDR
1326			CONFIG_VIDEO
1327			CONFIG_CMD_BMP
1328			CONFIG_CFB_CONSOLE
1329			CONFIG_VIDEO_SW_CURSOR
1330			CONFIG_VGA_AS_SINGLE_DEVICE
1331			CONFIG_VIDEO_LOGO
1332			CONFIG_VIDEO_BMP_LOGO
1333
1334		The DIU driver will look for the 'video-mode' environment
1335		variable, and if defined, enable the DIU as a console during
1336		boot.  See the documentation file README.video for a
1337		description of this variable.
1338
1339- Keyboard Support:
1340		CONFIG_KEYBOARD
1341
1342		Define this to enable a custom keyboard support.
1343		This simply calls drv_keyboard_init() which must be
1344		defined in your board-specific files.
1345		The only board using this so far is RBC823.
1346
1347- LCD Support:	CONFIG_LCD
1348
1349		Define this to enable LCD support (for output to LCD
1350		display); also select one of the supported displays
1351		by defining one of these:
1352
1353		CONFIG_ATMEL_LCD:
1354
1355			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1356
1357		CONFIG_NEC_NL6448AC33:
1358
1359			NEC NL6448AC33-18. Active, color, single scan.
1360
1361		CONFIG_NEC_NL6448BC20
1362
1363			NEC NL6448BC20-08. 6.5", 640x480.
1364			Active, color, single scan.
1365
1366		CONFIG_NEC_NL6448BC33_54
1367
1368			NEC NL6448BC33-54. 10.4", 640x480.
1369			Active, color, single scan.
1370
1371		CONFIG_SHARP_16x9
1372
1373			Sharp 320x240. Active, color, single scan.
1374			It isn't 16x9, and I am not sure what it is.
1375
1376		CONFIG_SHARP_LQ64D341
1377
1378			Sharp LQ64D341 display, 640x480.
1379			Active, color, single scan.
1380
1381		CONFIG_HLD1045
1382
1383			HLD1045 display, 640x480.
1384			Active, color, single scan.
1385
1386		CONFIG_OPTREX_BW
1387
1388			Optrex	 CBL50840-2 NF-FW 99 22 M5
1389			or
1390			Hitachi	 LMG6912RPFC-00T
1391			or
1392			Hitachi	 SP14Q002
1393
1394			320x240. Black & white.
1395
1396		Normally display is black on white background; define
1397		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1398
1399- Splash Screen Support: CONFIG_SPLASH_SCREEN
1400
1401		If this option is set, the environment is checked for
1402		a variable "splashimage". If found, the usual display
1403		of logo, copyright and system information on the LCD
1404		is suppressed and the BMP image at the address
1405		specified in "splashimage" is loaded instead. The
1406		console is redirected to the "nulldev", too. This
1407		allows for a "silent" boot where a splash screen is
1408		loaded very quickly after power-on.
1409
1410		CONFIG_SPLASH_SCREEN_ALIGN
1411
1412		If this option is set the splash image can be freely positioned
1413		on the screen. Environment variable "splashpos" specifies the
1414		position as "x,y". If a positive number is given it is used as
1415		number of pixel from left/top. If a negative number is given it
1416		is used as number of pixel from right/bottom. You can also
1417		specify 'm' for centering the image.
1418
1419		Example:
1420		setenv splashpos m,m
1421			=> image at center of screen
1422
1423		setenv splashpos 30,20
1424			=> image at x = 30 and y = 20
1425
1426		setenv splashpos -10,m
1427			=> vertically centered image
1428			   at x = dspWidth - bmpWidth - 9
1429
1430- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1431
1432		If this option is set, additionally to standard BMP
1433		images, gzipped BMP images can be displayed via the
1434		splashscreen support or the bmp command.
1435
1436- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1437
1438		If this option is set, 8-bit RLE compressed BMP images
1439		can be displayed via the splashscreen support or the
1440		bmp command.
1441
1442- Compression support:
1443		CONFIG_BZIP2
1444
1445		If this option is set, support for bzip2 compressed
1446		images is included. If not, only uncompressed and gzip
1447		compressed images are supported.
1448
1449		NOTE: the bzip2 algorithm requires a lot of RAM, so
1450		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1451		be at least 4MB.
1452
1453		CONFIG_LZMA
1454
1455		If this option is set, support for lzma compressed
1456		images is included.
1457
1458		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1459		requires an amount of dynamic memory that is given by the
1460		formula:
1461
1462			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1463
1464		Where lc and lp stand for, respectively, Literal context bits
1465		and Literal pos bits.
1466
1467		This value is upper-bounded by 14MB in the worst case. Anyway,
1468		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1469		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1470		a very small buffer.
1471
1472		Use the lzmainfo tool to determinate the lc and lp values and
1473		then calculate the amount of needed dynamic memory (ensuring
1474		the appropriate CONFIG_SYS_MALLOC_LEN value).
1475
1476- MII/PHY support:
1477		CONFIG_PHY_ADDR
1478
1479		The address of PHY on MII bus.
1480
1481		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1482
1483		The clock frequency of the MII bus
1484
1485		CONFIG_PHY_GIGE
1486
1487		If this option is set, support for speed/duplex
1488		detection of gigabit PHY is included.
1489
1490		CONFIG_PHY_RESET_DELAY
1491
1492		Some PHY like Intel LXT971A need extra delay after
1493		reset before any MII register access is possible.
1494		For such PHY, set this option to the usec delay
1495		required. (minimum 300usec for LXT971A)
1496
1497		CONFIG_PHY_CMD_DELAY (ppc4xx)
1498
1499		Some PHY like Intel LXT971A need extra delay after
1500		command issued before MII status register can be read
1501
1502- Ethernet address:
1503		CONFIG_ETHADDR
1504		CONFIG_ETH1ADDR
1505		CONFIG_ETH2ADDR
1506		CONFIG_ETH3ADDR
1507		CONFIG_ETH4ADDR
1508		CONFIG_ETH5ADDR
1509
1510		Define a default value for Ethernet address to use
1511		for the respective Ethernet interface, in case this
1512		is not determined automatically.
1513
1514- IP address:
1515		CONFIG_IPADDR
1516
1517		Define a default value for the IP address to use for
1518		the default Ethernet interface, in case this is not
1519		determined through e.g. bootp.
1520		(Environment variable "ipaddr")
1521
1522- Server IP address:
1523		CONFIG_SERVERIP
1524
1525		Defines a default value for the IP address of a TFTP
1526		server to contact when using the "tftboot" command.
1527		(Environment variable "serverip")
1528
1529		CONFIG_KEEP_SERVERADDR
1530
1531		Keeps the server's MAC address, in the env 'serveraddr'
1532		for passing to bootargs (like Linux's netconsole option)
1533
1534- Gateway IP address:
1535		CONFIG_GATEWAYIP
1536
1537		Defines a default value for the IP address of the
1538		default router where packets to other networks are
1539		sent to.
1540		(Environment variable "gatewayip")
1541
1542- Subnet mask:
1543		CONFIG_NETMASK
1544
1545		Defines a default value for the subnet mask (or
1546		routing prefix) which is used to determine if an IP
1547		address belongs to the local subnet or needs to be
1548		forwarded through a router.
1549		(Environment variable "netmask")
1550
1551- Multicast TFTP Mode:
1552		CONFIG_MCAST_TFTP
1553
1554		Defines whether you want to support multicast TFTP as per
1555		rfc-2090; for example to work with atftp.  Lets lots of targets
1556		tftp down the same boot image concurrently.  Note: the Ethernet
1557		driver in use must provide a function: mcast() to join/leave a
1558		multicast group.
1559
1560- BOOTP Recovery Mode:
1561		CONFIG_BOOTP_RANDOM_DELAY
1562
1563		If you have many targets in a network that try to
1564		boot using BOOTP, you may want to avoid that all
1565		systems send out BOOTP requests at precisely the same
1566		moment (which would happen for instance at recovery
1567		from a power failure, when all systems will try to
1568		boot, thus flooding the BOOTP server. Defining
1569		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1570		inserted before sending out BOOTP requests. The
1571		following delays are inserted then:
1572
1573		1st BOOTP request:	delay 0 ... 1 sec
1574		2nd BOOTP request:	delay 0 ... 2 sec
1575		3rd BOOTP request:	delay 0 ... 4 sec
1576		4th and following
1577		BOOTP requests:		delay 0 ... 8 sec
1578
1579- DHCP Advanced Options:
1580		You can fine tune the DHCP functionality by defining
1581		CONFIG_BOOTP_* symbols:
1582
1583		CONFIG_BOOTP_SUBNETMASK
1584		CONFIG_BOOTP_GATEWAY
1585		CONFIG_BOOTP_HOSTNAME
1586		CONFIG_BOOTP_NISDOMAIN
1587		CONFIG_BOOTP_BOOTPATH
1588		CONFIG_BOOTP_BOOTFILESIZE
1589		CONFIG_BOOTP_DNS
1590		CONFIG_BOOTP_DNS2
1591		CONFIG_BOOTP_SEND_HOSTNAME
1592		CONFIG_BOOTP_NTPSERVER
1593		CONFIG_BOOTP_TIMEOFFSET
1594		CONFIG_BOOTP_VENDOREX
1595		CONFIG_BOOTP_MAY_FAIL
1596
1597		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1598		environment variable, not the BOOTP server.
1599
1600		CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
1601		after the configured retry count, the call will fail
1602		instead of starting over.  This can be used to fail over
1603		to Link-local IP address configuration if the DHCP server
1604		is not available.
1605
1606		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1607		serverip from a DHCP server, it is possible that more
1608		than one DNS serverip is offered to the client.
1609		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1610		serverip will be stored in the additional environment
1611		variable "dnsip2". The first DNS serverip is always
1612		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1613		is defined.
1614
1615		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1616		to do a dynamic update of a DNS server. To do this, they
1617		need the hostname of the DHCP requester.
1618		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1619		of the "hostname" environment variable is passed as
1620		option 12 to the DHCP server.
1621
1622		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1623
1624		A 32bit value in microseconds for a delay between
1625		receiving a "DHCP Offer" and sending the "DHCP Request".
1626		This fixes a problem with certain DHCP servers that don't
1627		respond 100% of the time to a "DHCP request". E.g. On an
1628		AT91RM9200 processor running at 180MHz, this delay needed
1629		to be *at least* 15,000 usec before a Windows Server 2003
1630		DHCP server would reply 100% of the time. I recommend at
1631		least 50,000 usec to be safe. The alternative is to hope
1632		that one of the retries will be successful but note that
1633		the DHCP timeout and retry process takes a longer than
1634		this delay.
1635
1636 - CDP Options:
1637		CONFIG_CDP_DEVICE_ID
1638
1639		The device id used in CDP trigger frames.
1640
1641		CONFIG_CDP_DEVICE_ID_PREFIX
1642
1643		A two character string which is prefixed to the MAC address
1644		of the device.
1645
1646		CONFIG_CDP_PORT_ID
1647
1648		A printf format string which contains the ascii name of
1649		the port. Normally is set to "eth%d" which sets
1650		eth0 for the first Ethernet, eth1 for the second etc.
1651
1652		CONFIG_CDP_CAPABILITIES
1653
1654		A 32bit integer which indicates the device capabilities;
1655		0x00000010 for a normal host which does not forwards.
1656
1657		CONFIG_CDP_VERSION
1658
1659		An ascii string containing the version of the software.
1660
1661		CONFIG_CDP_PLATFORM
1662
1663		An ascii string containing the name of the platform.
1664
1665		CONFIG_CDP_TRIGGER
1666
1667		A 32bit integer sent on the trigger.
1668
1669		CONFIG_CDP_POWER_CONSUMPTION
1670
1671		A 16bit integer containing the power consumption of the
1672		device in .1 of milliwatts.
1673
1674		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1675
1676		A byte containing the id of the VLAN.
1677
1678- Status LED:	CONFIG_STATUS_LED
1679
1680		Several configurations allow to display the current
1681		status using a LED. For instance, the LED will blink
1682		fast while running U-Boot code, stop blinking as
1683		soon as a reply to a BOOTP request was received, and
1684		start blinking slow once the Linux kernel is running
1685		(supported by a status LED driver in the Linux
1686		kernel). Defining CONFIG_STATUS_LED enables this
1687		feature in U-Boot.
1688
1689- CAN Support:	CONFIG_CAN_DRIVER
1690
1691		Defining CONFIG_CAN_DRIVER enables CAN driver support
1692		on those systems that support this (optional)
1693		feature, like the TQM8xxL modules.
1694
1695- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1696
1697		These enable I2C serial bus commands. Defining either of
1698		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1699		include the appropriate I2C driver for the selected CPU.
1700
1701		This will allow you to use i2c commands at the u-boot
1702		command line (as long as you set CONFIG_CMD_I2C in
1703		CONFIG_COMMANDS) and communicate with i2c based realtime
1704		clock chips. See common/cmd_i2c.c for a description of the
1705		command line interface.
1706
1707		CONFIG_HARD_I2C selects a hardware I2C controller.
1708
1709		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1710		bit-banging) driver instead of CPM or similar hardware
1711		support for I2C.
1712
1713		There are several other quantities that must also be
1714		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1715
1716		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1717		to be the frequency (in Hz) at which you wish your i2c bus
1718		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1719		the CPU's i2c node address).
1720
1721		Now, the u-boot i2c code for the mpc8xx
1722		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1723		and so its address should therefore be cleared to 0 (See,
1724		eg, MPC823e User's Manual p.16-473). So, set
1725		CONFIG_SYS_I2C_SLAVE to 0.
1726
1727		CONFIG_SYS_I2C_INIT_MPC5XXX
1728
1729		When a board is reset during an i2c bus transfer
1730		chips might think that the current transfer is still
1731		in progress.  Reset the slave devices by sending start
1732		commands until the slave device responds.
1733
1734		That's all that's required for CONFIG_HARD_I2C.
1735
1736		If you use the software i2c interface (CONFIG_SOFT_I2C)
1737		then the following macros need to be defined (examples are
1738		from include/configs/lwmon.h):
1739
1740		I2C_INIT
1741
1742		(Optional). Any commands necessary to enable the I2C
1743		controller or configure ports.
1744
1745		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1746
1747		I2C_PORT
1748
1749		(Only for MPC8260 CPU). The I/O port to use (the code
1750		assumes both bits are on the same port). Valid values
1751		are 0..3 for ports A..D.
1752
1753		I2C_ACTIVE
1754
1755		The code necessary to make the I2C data line active
1756		(driven).  If the data line is open collector, this
1757		define can be null.
1758
1759		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1760
1761		I2C_TRISTATE
1762
1763		The code necessary to make the I2C data line tri-stated
1764		(inactive).  If the data line is open collector, this
1765		define can be null.
1766
1767		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1768
1769		I2C_READ
1770
1771		Code that returns TRUE if the I2C data line is high,
1772		FALSE if it is low.
1773
1774		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1775
1776		I2C_SDA(bit)
1777
1778		If <bit> is TRUE, sets the I2C data line high. If it
1779		is FALSE, it clears it (low).
1780
1781		eg: #define I2C_SDA(bit) \
1782			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1783			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1784
1785		I2C_SCL(bit)
1786
1787		If <bit> is TRUE, sets the I2C clock line high. If it
1788		is FALSE, it clears it (low).
1789
1790		eg: #define I2C_SCL(bit) \
1791			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1792			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1793
1794		I2C_DELAY
1795
1796		This delay is invoked four times per clock cycle so this
1797		controls the rate of data transfer.  The data rate thus
1798		is 1 / (I2C_DELAY * 4). Often defined to be something
1799		like:
1800
1801		#define I2C_DELAY  udelay(2)
1802
1803		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1804
1805		If your arch supports the generic GPIO framework (asm/gpio.h),
1806		then you may alternatively define the two GPIOs that are to be
1807		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1808		have GPIO-based defaults assigned to them as appropriate.
1809
1810		You should define these to the GPIO value as given directly to
1811		the generic GPIO functions.
1812
1813		CONFIG_SYS_I2C_INIT_BOARD
1814
1815		When a board is reset during an i2c bus transfer
1816		chips might think that the current transfer is still
1817		in progress. On some boards it is possible to access
1818		the i2c SCLK line directly, either by using the
1819		processor pin as a GPIO or by having a second pin
1820		connected to the bus. If this option is defined a
1821		custom i2c_init_board() routine in boards/xxx/board.c
1822		is run early in the boot sequence.
1823
1824		CONFIG_SYS_I2C_BOARD_LATE_INIT
1825
1826		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1827		defined a custom i2c_board_late_init() routine in
1828		boards/xxx/board.c is run AFTER the operations in i2c_init()
1829		is completed. This callpoint can be used to unreset i2c bus
1830		using CPU i2c controller register accesses for CPUs whose i2c
1831		controller provide such a method. It is called at the end of
1832		i2c_init() to allow i2c_init operations to setup the i2c bus
1833		controller on the CPU (e.g. setting bus speed & slave address).
1834
1835		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1836
1837		This option enables configuration of bi_iic_fast[] flags
1838		in u-boot bd_info structure based on u-boot environment
1839		variable "i2cfast". (see also i2cfast)
1840
1841		CONFIG_I2C_MULTI_BUS
1842
1843		This option allows the use of multiple I2C buses, each of which
1844		must have a controller.	 At any point in time, only one bus is
1845		active.	 To switch to a different bus, use the 'i2c dev' command.
1846		Note that bus numbering is zero-based.
1847
1848		CONFIG_SYS_I2C_NOPROBES
1849
1850		This option specifies a list of I2C devices that will be skipped
1851		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1852		is set, specify a list of bus-device pairs.  Otherwise, specify
1853		a 1D array of device addresses
1854
1855		e.g.
1856			#undef	CONFIG_I2C_MULTI_BUS
1857			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1858
1859		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1860
1861			#define CONFIG_I2C_MULTI_BUS
1862			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1863
1864		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1865
1866		CONFIG_SYS_SPD_BUS_NUM
1867
1868		If defined, then this indicates the I2C bus number for DDR SPD.
1869		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1870
1871		CONFIG_SYS_RTC_BUS_NUM
1872
1873		If defined, then this indicates the I2C bus number for the RTC.
1874		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1875
1876		CONFIG_SYS_DTT_BUS_NUM
1877
1878		If defined, then this indicates the I2C bus number for the DTT.
1879		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1880
1881		CONFIG_SYS_I2C_DTT_ADDR:
1882
1883		If defined, specifies the I2C address of the DTT device.
1884		If not defined, then U-Boot uses predefined value for
1885		specified DTT device.
1886
1887		CONFIG_FSL_I2C
1888
1889		Define this option if you want to use Freescale's I2C driver in
1890		drivers/i2c/fsl_i2c.c.
1891
1892		CONFIG_I2C_MUX
1893
1894		Define this option if you have I2C devices reached over 1 .. n
1895		I2C Muxes like the pca9544a. This option addes a new I2C
1896		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1897		new I2C Bus to the existing I2C Busses. If you select the
1898		new Bus with "i2c dev", u-bbot sends first the commandos for
1899		the muxes to activate this new "bus".
1900
1901		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1902		feature!
1903
1904		Example:
1905		Adding a new I2C Bus reached over 2 pca9544a muxes
1906			The First mux with address 70 and channel 6
1907			The Second mux with address 71 and channel 4
1908
1909		=> i2c bus pca9544a:70:6:pca9544a:71:4
1910
1911		Use the "i2c bus" command without parameter, to get a list
1912		of I2C Busses with muxes:
1913
1914		=> i2c bus
1915		Busses reached over muxes:
1916		Bus ID: 2
1917		  reached over Mux(es):
1918		    pca9544a@70 ch: 4
1919		Bus ID: 3
1920		  reached over Mux(es):
1921		    pca9544a@70 ch: 6
1922		    pca9544a@71 ch: 4
1923		=>
1924
1925		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1926		u-boot first sends the command to the mux@70 to enable
1927		channel 6, and then the command to the mux@71 to enable
1928		the channel 4.
1929
1930		After that, you can use the "normal" i2c commands as
1931		usual to communicate with your I2C devices behind
1932		the 2 muxes.
1933
1934		This option is actually implemented for the bitbanging
1935		algorithm in common/soft_i2c.c and for the Hardware I2C
1936		Bus on the MPC8260. But it should be not so difficult
1937		to add this option to other architectures.
1938
1939		CONFIG_SOFT_I2C_READ_REPEATED_START
1940
1941		defining this will force the i2c_read() function in
1942		the soft_i2c driver to perform an I2C repeated start
1943		between writing the address pointer and reading the
1944		data.  If this define is omitted the default behaviour
1945		of doing a stop-start sequence will be used.  Most I2C
1946		devices can use either method, but some require one or
1947		the other.
1948
1949- SPI Support:	CONFIG_SPI
1950
1951		Enables SPI driver (so far only tested with
1952		SPI EEPROM, also an instance works with Crystal A/D and
1953		D/As on the SACSng board)
1954
1955		CONFIG_SH_SPI
1956
1957		Enables the driver for SPI controller on SuperH. Currently
1958		only SH7757 is supported.
1959
1960		CONFIG_SPI_X
1961
1962		Enables extended (16-bit) SPI EEPROM addressing.
1963		(symmetrical to CONFIG_I2C_X)
1964
1965		CONFIG_SOFT_SPI
1966
1967		Enables a software (bit-bang) SPI driver rather than
1968		using hardware support. This is a general purpose
1969		driver that only requires three general I/O port pins
1970		(two outputs, one input) to function. If this is
1971		defined, the board configuration must define several
1972		SPI configuration items (port pins to use, etc). For
1973		an example, see include/configs/sacsng.h.
1974
1975		CONFIG_HARD_SPI
1976
1977		Enables a hardware SPI driver for general-purpose reads
1978		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1979		must define a list of chip-select function pointers.
1980		Currently supported on some MPC8xxx processors.	 For an
1981		example, see include/configs/mpc8349emds.h.
1982
1983		CONFIG_MXC_SPI
1984
1985		Enables the driver for the SPI controllers on i.MX and MXC
1986		SoCs. Currently i.MX31/35/51 are supported.
1987
1988- FPGA Support: CONFIG_FPGA
1989
1990		Enables FPGA subsystem.
1991
1992		CONFIG_FPGA_<vendor>
1993
1994		Enables support for specific chip vendors.
1995		(ALTERA, XILINX)
1996
1997		CONFIG_FPGA_<family>
1998
1999		Enables support for FPGA family.
2000		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
2001
2002		CONFIG_FPGA_COUNT
2003
2004		Specify the number of FPGA devices to support.
2005
2006		CONFIG_SYS_FPGA_PROG_FEEDBACK
2007
2008		Enable printing of hash marks during FPGA configuration.
2009
2010		CONFIG_SYS_FPGA_CHECK_BUSY
2011
2012		Enable checks on FPGA configuration interface busy
2013		status by the configuration function. This option
2014		will require a board or device specific function to
2015		be written.
2016
2017		CONFIG_FPGA_DELAY
2018
2019		If defined, a function that provides delays in the FPGA
2020		configuration driver.
2021
2022		CONFIG_SYS_FPGA_CHECK_CTRLC
2023		Allow Control-C to interrupt FPGA configuration
2024
2025		CONFIG_SYS_FPGA_CHECK_ERROR
2026
2027		Check for configuration errors during FPGA bitfile
2028		loading. For example, abort during Virtex II
2029		configuration if the INIT_B line goes low (which
2030		indicated a CRC error).
2031
2032		CONFIG_SYS_FPGA_WAIT_INIT
2033
2034		Maximum time to wait for the INIT_B line to deassert
2035		after PROB_B has been deasserted during a Virtex II
2036		FPGA configuration sequence. The default time is 500
2037		ms.
2038
2039		CONFIG_SYS_FPGA_WAIT_BUSY
2040
2041		Maximum time to wait for BUSY to deassert during
2042		Virtex II FPGA configuration. The default is 5 ms.
2043
2044		CONFIG_SYS_FPGA_WAIT_CONFIG
2045
2046		Time to wait after FPGA configuration. The default is
2047		200 ms.
2048
2049- Configuration Management:
2050		CONFIG_IDENT_STRING
2051
2052		If defined, this string will be added to the U-Boot
2053		version information (U_BOOT_VERSION)
2054
2055- Vendor Parameter Protection:
2056
2057		U-Boot considers the values of the environment
2058		variables "serial#" (Board Serial Number) and
2059		"ethaddr" (Ethernet Address) to be parameters that
2060		are set once by the board vendor / manufacturer, and
2061		protects these variables from casual modification by
2062		the user. Once set, these variables are read-only,
2063		and write or delete attempts are rejected. You can
2064		change this behaviour:
2065
2066		If CONFIG_ENV_OVERWRITE is #defined in your config
2067		file, the write protection for vendor parameters is
2068		completely disabled. Anybody can change or delete
2069		these parameters.
2070
2071		Alternatively, if you #define _both_ CONFIG_ETHADDR
2072		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2073		Ethernet address is installed in the environment,
2074		which can be changed exactly ONCE by the user. [The
2075		serial# is unaffected by this, i. e. it remains
2076		read-only.]
2077
2078- Protected RAM:
2079		CONFIG_PRAM
2080
2081		Define this variable to enable the reservation of
2082		"protected RAM", i. e. RAM which is not overwritten
2083		by U-Boot. Define CONFIG_PRAM to hold the number of
2084		kB you want to reserve for pRAM. You can overwrite
2085		this default value by defining an environment
2086		variable "pram" to the number of kB you want to
2087		reserve. Note that the board info structure will
2088		still show the full amount of RAM. If pRAM is
2089		reserved, a new environment variable "mem" will
2090		automatically be defined to hold the amount of
2091		remaining RAM in a form that can be passed as boot
2092		argument to Linux, for instance like that:
2093
2094			setenv bootargs ... mem=\${mem}
2095			saveenv
2096
2097		This way you can tell Linux not to use this memory,
2098		either, which results in a memory region that will
2099		not be affected by reboots.
2100
2101		*WARNING* If your board configuration uses automatic
2102		detection of the RAM size, you must make sure that
2103		this memory test is non-destructive. So far, the
2104		following board configurations are known to be
2105		"pRAM-clean":
2106
2107			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
2108			HERMES, IP860, RPXlite, LWMON, LANTEC,
2109			FLAGADM, TQM8260
2110
2111- Error Recovery:
2112		CONFIG_PANIC_HANG
2113
2114		Define this variable to stop the system in case of a
2115		fatal error, so that you have to reset it manually.
2116		This is probably NOT a good idea for an embedded
2117		system where you want the system to reboot
2118		automatically as fast as possible, but it may be
2119		useful during development since you can try to debug
2120		the conditions that lead to the situation.
2121
2122		CONFIG_NET_RETRY_COUNT
2123
2124		This variable defines the number of retries for
2125		network operations like ARP, RARP, TFTP, or BOOTP
2126		before giving up the operation. If not defined, a
2127		default value of 5 is used.
2128
2129		CONFIG_ARP_TIMEOUT
2130
2131		Timeout waiting for an ARP reply in milliseconds.
2132
2133- Command Interpreter:
2134		CONFIG_AUTO_COMPLETE
2135
2136		Enable auto completion of commands using TAB.
2137
2138		Note that this feature has NOT been implemented yet
2139		for the "hush" shell.
2140
2141
2142		CONFIG_SYS_HUSH_PARSER
2143
2144		Define this variable to enable the "hush" shell (from
2145		Busybox) as command line interpreter, thus enabling
2146		powerful command line syntax like
2147		if...then...else...fi conditionals or `&&' and '||'
2148		constructs ("shell scripts").
2149
2150		If undefined, you get the old, much simpler behaviour
2151		with a somewhat smaller memory footprint.
2152
2153
2154		CONFIG_SYS_PROMPT_HUSH_PS2
2155
2156		This defines the secondary prompt string, which is
2157		printed when the command interpreter needs more input
2158		to complete a command. Usually "> ".
2159
2160	Note:
2161
2162		In the current implementation, the local variables
2163		space and global environment variables space are
2164		separated. Local variables are those you define by
2165		simply typing `name=value'. To access a local
2166		variable later on, you have write `$name' or
2167		`${name}'; to execute the contents of a variable
2168		directly type `$name' at the command prompt.
2169
2170		Global environment variables are those you use
2171		setenv/printenv to work with. To run a command stored
2172		in such a variable, you need to use the run command,
2173		and you must not use the '$' sign to access them.
2174
2175		To store commands and special characters in a
2176		variable, please use double quotation marks
2177		surrounding the whole text of the variable, instead
2178		of the backslashes before semicolons and special
2179		symbols.
2180
2181- Commandline Editing and History:
2182		CONFIG_CMDLINE_EDITING
2183
2184		Enable editing and History functions for interactive
2185		commandline input operations
2186
2187- Default Environment:
2188		CONFIG_EXTRA_ENV_SETTINGS
2189
2190		Define this to contain any number of null terminated
2191		strings (variable = value pairs) that will be part of
2192		the default environment compiled into the boot image.
2193
2194		For example, place something like this in your
2195		board's config file:
2196
2197		#define CONFIG_EXTRA_ENV_SETTINGS \
2198			"myvar1=value1\0" \
2199			"myvar2=value2\0"
2200
2201		Warning: This method is based on knowledge about the
2202		internal format how the environment is stored by the
2203		U-Boot code. This is NOT an official, exported
2204		interface! Although it is unlikely that this format
2205		will change soon, there is no guarantee either.
2206		You better know what you are doing here.
2207
2208		Note: overly (ab)use of the default environment is
2209		discouraged. Make sure to check other ways to preset
2210		the environment like the "source" command or the
2211		boot command first.
2212
2213- DataFlash Support:
2214		CONFIG_HAS_DATAFLASH
2215
2216		Defining this option enables DataFlash features and
2217		allows to read/write in Dataflash via the standard
2218		commands cp, md...
2219
2220- Serial Flash support
2221		CONFIG_CMD_SF
2222
2223		Defining this option enables SPI flash commands
2224		'sf probe/read/write/erase/update'.
2225
2226		Usage requires an initial 'probe' to define the serial
2227		flash parameters, followed by read/write/erase/update
2228		commands.
2229
2230		The following defaults may be provided by the platform
2231		to handle the common case when only a single serial
2232		flash is present on the system.
2233
2234		CONFIG_SF_DEFAULT_BUS		Bus identifier
2235		CONFIG_SF_DEFAULT_CS		Chip-select
2236		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2237		CONFIG_SF_DEFAULT_SPEED		in Hz
2238
2239- SystemACE Support:
2240		CONFIG_SYSTEMACE
2241
2242		Adding this option adds support for Xilinx SystemACE
2243		chips attached via some sort of local bus. The address
2244		of the chip must also be defined in the
2245		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2246
2247		#define CONFIG_SYSTEMACE
2248		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2249
2250		When SystemACE support is added, the "ace" device type
2251		becomes available to the fat commands, i.e. fatls.
2252
2253- TFTP Fixed UDP Port:
2254		CONFIG_TFTP_PORT
2255
2256		If this is defined, the environment variable tftpsrcp
2257		is used to supply the TFTP UDP source port value.
2258		If tftpsrcp isn't defined, the normal pseudo-random port
2259		number generator is used.
2260
2261		Also, the environment variable tftpdstp is used to supply
2262		the TFTP UDP destination port value.  If tftpdstp isn't
2263		defined, the normal port 69 is used.
2264
2265		The purpose for tftpsrcp is to allow a TFTP server to
2266		blindly start the TFTP transfer using the pre-configured
2267		target IP address and UDP port. This has the effect of
2268		"punching through" the (Windows XP) firewall, allowing
2269		the remainder of the TFTP transfer to proceed normally.
2270		A better solution is to properly configure the firewall,
2271		but sometimes that is not allowed.
2272
2273- Show boot progress:
2274		CONFIG_SHOW_BOOT_PROGRESS
2275
2276		Defining this option allows to add some board-
2277		specific code (calling a user-provided function
2278		"show_boot_progress(int)") that enables you to show
2279		the system's boot progress on some display (for
2280		example, some LED's) on your board. At the moment,
2281		the following checkpoints are implemented:
2282
2283- Detailed boot stage timing
2284		CONFIG_BOOTSTAGE
2285		Define this option to get detailed timing of each stage
2286		of the boot process.
2287
2288		CONFIG_BOOTSTAGE_USER_COUNT
2289		This is the number of available user bootstage records.
2290		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2291		a new ID will be allocated from this stash. If you exceed
2292		the limit, recording will stop.
2293
2294		CONFIG_BOOTSTAGE_REPORT
2295		Define this to print a report before boot, similar to this:
2296
2297		Timer summary in microseconds:
2298		       Mark    Elapsed  Stage
2299			  0          0  reset
2300		  3,575,678  3,575,678  board_init_f start
2301		  3,575,695         17  arch_cpu_init A9
2302		  3,575,777         82  arch_cpu_init done
2303		  3,659,598     83,821  board_init_r start
2304		  3,910,375    250,777  main_loop
2305		 29,916,167 26,005,792  bootm_start
2306		 30,361,327    445,160  start_kernel
2307
2308Legacy uImage format:
2309
2310  Arg	Where			When
2311    1	common/cmd_bootm.c	before attempting to boot an image
2312   -1	common/cmd_bootm.c	Image header has bad	 magic number
2313    2	common/cmd_bootm.c	Image header has correct magic number
2314   -2	common/cmd_bootm.c	Image header has bad	 checksum
2315    3	common/cmd_bootm.c	Image header has correct checksum
2316   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2317    4	common/cmd_bootm.c	Image data   has correct checksum
2318   -4	common/cmd_bootm.c	Image is for unsupported architecture
2319    5	common/cmd_bootm.c	Architecture check OK
2320   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2321    6	common/cmd_bootm.c	Image Type check OK
2322   -6	common/cmd_bootm.c	gunzip uncompression error
2323   -7	common/cmd_bootm.c	Unimplemented compression type
2324    7	common/cmd_bootm.c	Uncompression OK
2325    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2326   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2327
2328    9	common/image.c		Start initial ramdisk verification
2329  -10	common/image.c		Ramdisk header has bad	   magic number
2330  -11	common/image.c		Ramdisk header has bad	   checksum
2331   10	common/image.c		Ramdisk header is OK
2332  -12	common/image.c		Ramdisk data   has bad	   checksum
2333   11	common/image.c		Ramdisk data   has correct checksum
2334   12	common/image.c		Ramdisk verification complete, start loading
2335  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2336   13	common/image.c		Start multifile image verification
2337   14	common/image.c		No initial ramdisk, no multifile, continue.
2338
2339   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2340
2341  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2342  -31	post/post.c		POST test failed, detected by post_output_backlog()
2343  -32	post/post.c		POST test failed, detected by post_run_single()
2344
2345   34	common/cmd_doc.c	before loading a Image from a DOC device
2346  -35	common/cmd_doc.c	Bad usage of "doc" command
2347   35	common/cmd_doc.c	correct usage of "doc" command
2348  -36	common/cmd_doc.c	No boot device
2349   36	common/cmd_doc.c	correct boot device
2350  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2351   37	common/cmd_doc.c	correct chip ID found, device available
2352  -38	common/cmd_doc.c	Read Error on boot device
2353   38	common/cmd_doc.c	reading Image header from DOC device OK
2354  -39	common/cmd_doc.c	Image header has bad magic number
2355   39	common/cmd_doc.c	Image header has correct magic number
2356  -40	common/cmd_doc.c	Error reading Image from DOC device
2357   40	common/cmd_doc.c	Image header has correct magic number
2358   41	common/cmd_ide.c	before loading a Image from a IDE device
2359  -42	common/cmd_ide.c	Bad usage of "ide" command
2360   42	common/cmd_ide.c	correct usage of "ide" command
2361  -43	common/cmd_ide.c	No boot device
2362   43	common/cmd_ide.c	boot device found
2363  -44	common/cmd_ide.c	Device not available
2364   44	common/cmd_ide.c	Device available
2365  -45	common/cmd_ide.c	wrong partition selected
2366   45	common/cmd_ide.c	partition selected
2367  -46	common/cmd_ide.c	Unknown partition table
2368   46	common/cmd_ide.c	valid partition table found
2369  -47	common/cmd_ide.c	Invalid partition type
2370   47	common/cmd_ide.c	correct partition type
2371  -48	common/cmd_ide.c	Error reading Image Header on boot device
2372   48	common/cmd_ide.c	reading Image Header from IDE device OK
2373  -49	common/cmd_ide.c	Image header has bad magic number
2374   49	common/cmd_ide.c	Image header has correct magic number
2375  -50	common/cmd_ide.c	Image header has bad	 checksum
2376   50	common/cmd_ide.c	Image header has correct checksum
2377  -51	common/cmd_ide.c	Error reading Image from IDE device
2378   51	common/cmd_ide.c	reading Image from IDE device OK
2379   52	common/cmd_nand.c	before loading a Image from a NAND device
2380  -53	common/cmd_nand.c	Bad usage of "nand" command
2381   53	common/cmd_nand.c	correct usage of "nand" command
2382  -54	common/cmd_nand.c	No boot device
2383   54	common/cmd_nand.c	boot device found
2384  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2385   55	common/cmd_nand.c	correct chip ID found, device available
2386  -56	common/cmd_nand.c	Error reading Image Header on boot device
2387   56	common/cmd_nand.c	reading Image Header from NAND device OK
2388  -57	common/cmd_nand.c	Image header has bad magic number
2389   57	common/cmd_nand.c	Image header has correct magic number
2390  -58	common/cmd_nand.c	Error reading Image from NAND device
2391   58	common/cmd_nand.c	reading Image from NAND device OK
2392
2393  -60	common/env_common.c	Environment has a bad CRC, using default
2394
2395   64	net/eth.c		starting with Ethernet configuration.
2396  -64	net/eth.c		no Ethernet found.
2397   65	net/eth.c		Ethernet found.
2398
2399  -80	common/cmd_net.c	usage wrong
2400   80	common/cmd_net.c	before calling NetLoop()
2401  -81	common/cmd_net.c	some error in NetLoop() occurred
2402   81	common/cmd_net.c	NetLoop() back without error
2403  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2404   82	common/cmd_net.c	trying automatic boot
2405   83	common/cmd_net.c	running "source" command
2406  -83	common/cmd_net.c	some error in automatic boot or "source" command
2407   84	common/cmd_net.c	end without errors
2408
2409FIT uImage format:
2410
2411  Arg	Where			When
2412  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2413 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2414  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2415 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2416  102	common/cmd_bootm.c	Kernel unit name specified
2417 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2418  103	common/cmd_bootm.c	Found configuration node
2419  104	common/cmd_bootm.c	Got kernel subimage node offset
2420 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2421  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2422 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2423  106	common/cmd_bootm.c	Architecture check OK
2424 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2425  107	common/cmd_bootm.c	Kernel subimage type OK
2426 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2427  108	common/cmd_bootm.c	Got kernel subimage data/size
2428 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2429 -109	common/cmd_bootm.c	Can't get kernel subimage type
2430 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2431 -111	common/cmd_bootm.c	Can't get kernel subimage os
2432 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2433 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2434
2435  120	common/image.c		Start initial ramdisk verification
2436 -120	common/image.c		Ramdisk FIT image has incorrect format
2437  121	common/image.c		Ramdisk FIT image has correct format
2438  122	common/image.c		No ramdisk subimage unit name, using configuration
2439 -122	common/image.c		Can't get configuration for ramdisk subimage
2440  123	common/image.c		Ramdisk unit name specified
2441 -124	common/image.c		Can't get ramdisk subimage node offset
2442  125	common/image.c		Got ramdisk subimage node offset
2443 -125	common/image.c		Ramdisk subimage hash verification failed
2444  126	common/image.c		Ramdisk subimage hash verification OK
2445 -126	common/image.c		Ramdisk subimage for unsupported architecture
2446  127	common/image.c		Architecture check OK
2447 -127	common/image.c		Can't get ramdisk subimage data/size
2448  128	common/image.c		Got ramdisk subimage data/size
2449  129	common/image.c		Can't get ramdisk load address
2450 -129	common/image.c		Got ramdisk load address
2451
2452 -130	common/cmd_doc.c	Incorrect FIT image format
2453  131	common/cmd_doc.c	FIT image format OK
2454
2455 -140	common/cmd_ide.c	Incorrect FIT image format
2456  141	common/cmd_ide.c	FIT image format OK
2457
2458 -150	common/cmd_nand.c	Incorrect FIT image format
2459  151	common/cmd_nand.c	FIT image format OK
2460
2461- Standalone program support:
2462		CONFIG_STANDALONE_LOAD_ADDR
2463
2464		This option defines a board specific value for the
2465		address where standalone program gets loaded, thus
2466		overwriting the architecture dependent default
2467		settings.
2468
2469- Frame Buffer Address:
2470		CONFIG_FB_ADDR
2471
2472		Define CONFIG_FB_ADDR if you want to use specific
2473		address for frame buffer.
2474		Then system will reserve the frame buffer address to
2475		defined address instead of lcd_setmem (this function
2476		grabs the memory for frame buffer by panel's size).
2477
2478		Please see board_init_f function.
2479
2480- Automatic software updates via TFTP server
2481		CONFIG_UPDATE_TFTP
2482		CONFIG_UPDATE_TFTP_CNT_MAX
2483		CONFIG_UPDATE_TFTP_MSEC_MAX
2484
2485		These options enable and control the auto-update feature;
2486		for a more detailed description refer to doc/README.update.
2487
2488- MTD Support (mtdparts command, UBI support)
2489		CONFIG_MTD_DEVICE
2490
2491		Adds the MTD device infrastructure from the Linux kernel.
2492		Needed for mtdparts command support.
2493
2494		CONFIG_MTD_PARTITIONS
2495
2496		Adds the MTD partitioning infrastructure from the Linux
2497		kernel. Needed for UBI support.
2498
2499- SPL framework
2500		CONFIG_SPL
2501		Enable building of SPL globally.
2502
2503		CONFIG_SPL_LDSCRIPT
2504		LDSCRIPT for linking the SPL binary.
2505
2506		CONFIG_SPL_MAX_SIZE
2507		Maximum binary size (text, data and rodata) of the SPL binary.
2508
2509		CONFIG_SPL_TEXT_BASE
2510		TEXT_BASE for linking the SPL binary.
2511
2512		CONFIG_SPL_BSS_START_ADDR
2513		Link address for the BSS within the SPL binary.
2514
2515		CONFIG_SPL_BSS_MAX_SIZE
2516		Maximum binary size of the BSS section of the SPL binary.
2517
2518		CONFIG_SPL_STACK
2519		Adress of the start of the stack SPL will use
2520
2521		CONFIG_SYS_SPL_MALLOC_START
2522		Starting address of the malloc pool used in SPL.
2523
2524		CONFIG_SYS_SPL_MALLOC_SIZE
2525		The size of the malloc pool used in SPL.
2526
2527		CONFIG_SPL_LIBCOMMON_SUPPORT
2528		Support for common/libcommon.o in SPL binary
2529
2530		CONFIG_SPL_LIBDISK_SUPPORT
2531		Support for disk/libdisk.o in SPL binary
2532
2533		CONFIG_SPL_I2C_SUPPORT
2534		Support for drivers/i2c/libi2c.o in SPL binary
2535
2536		CONFIG_SPL_GPIO_SUPPORT
2537		Support for drivers/gpio/libgpio.o in SPL binary
2538
2539		CONFIG_SPL_MMC_SUPPORT
2540		Support for drivers/mmc/libmmc.o in SPL binary
2541
2542		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR,
2543		CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS,
2544		CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION
2545		Address, size and partition on the MMC to load U-Boot from
2546		when the MMC is being used in raw mode.
2547
2548		CONFIG_SPL_FAT_SUPPORT
2549		Support for fs/fat/libfat.o in SPL binary
2550
2551		CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME
2552		Filename to read to load U-Boot when reading from FAT
2553
2554		CONFIG_SPL_NAND_SIMPLE
2555		Support for drivers/mtd/nand/libnand.o in SPL binary
2556
2557		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
2558		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
2559		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
2560		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
2561		CONFIG_SYS_NAND_ECCBYTES
2562		Defines the size and behavior of the NAND that SPL uses
2563		to read U-Boot with CONFIG_SPL_NAND_SIMPLE
2564
2565		CONFIG_SYS_NAND_U_BOOT_OFFS
2566		Location in NAND for CONFIG_SPL_NAND_SIMPLE to read U-Boot
2567		from.
2568
2569		CONFIG_SYS_NAND_U_BOOT_START
2570		Location in memory for CONFIG_SPL_NAND_SIMPLE to load U-Boot
2571		to.
2572
2573		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
2574		Define this if you need to first read the OOB and then the
2575		data. This is used for example on davinci plattforms.
2576
2577		CONFIG_SPL_OMAP3_ID_NAND
2578		Support for an OMAP3-specific set of functions to return the
2579		ID and MFR of the first attached NAND chip, if present.
2580
2581		CONFIG_SPL_SERIAL_SUPPORT
2582		Support for drivers/serial/libserial.o in SPL binary
2583
2584		CONFIG_SPL_SPI_FLASH_SUPPORT
2585		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2586
2587		CONFIG_SPL_SPI_SUPPORT
2588		Support for drivers/spi/libspi.o in SPL binary
2589
2590		CONFIG_SPL_LIBGENERIC_SUPPORT
2591		Support for lib/libgeneric.o in SPL binary
2592
2593Modem Support:
2594--------------
2595
2596[so far only for SMDK2400 boards]
2597
2598- Modem support enable:
2599		CONFIG_MODEM_SUPPORT
2600
2601- RTS/CTS Flow control enable:
2602		CONFIG_HWFLOW
2603
2604- Modem debug support:
2605		CONFIG_MODEM_SUPPORT_DEBUG
2606
2607		Enables debugging stuff (char screen[1024], dbg())
2608		for modem support. Useful only with BDI2000.
2609
2610- Interrupt support (PPC):
2611
2612		There are common interrupt_init() and timer_interrupt()
2613		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2614		for CPU specific initialization. interrupt_init_cpu()
2615		should set decrementer_count to appropriate value. If
2616		CPU resets decrementer automatically after interrupt
2617		(ppc4xx) it should set decrementer_count to zero.
2618		timer_interrupt() calls timer_interrupt_cpu() for CPU
2619		specific handling. If board has watchdog / status_led
2620		/ other_activity_monitor it works automatically from
2621		general timer_interrupt().
2622
2623- General:
2624
2625		In the target system modem support is enabled when a
2626		specific key (key combination) is pressed during
2627		power-on. Otherwise U-Boot will boot normally
2628		(autoboot). The key_pressed() function is called from
2629		board_init(). Currently key_pressed() is a dummy
2630		function, returning 1 and thus enabling modem
2631		initialization.
2632
2633		If there are no modem init strings in the
2634		environment, U-Boot proceed to autoboot; the
2635		previous output (banner, info printfs) will be
2636		suppressed, though.
2637
2638		See also: doc/README.Modem
2639
2640Board initialization settings:
2641------------------------------
2642
2643During Initialization u-boot calls a number of board specific functions
2644to allow the preparation of board specific prerequisites, e.g. pin setup
2645before drivers are initialized. To enable these callbacks the
2646following configuration macros have to be defined. Currently this is
2647architecture specific, so please check arch/your_architecture/lib/board.c
2648typically in board_init_f() and board_init_r().
2649
2650- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2651- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2652- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2653- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2654
2655Configuration Settings:
2656-----------------------
2657
2658- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2659		undefine this when you're short of memory.
2660
2661- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2662		width of the commands listed in the 'help' command output.
2663
2664- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2665		prompt for user input.
2666
2667- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2668
2669- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2670
2671- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2672
2673- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2674		the application (usually a Linux kernel) when it is
2675		booted
2676
2677- CONFIG_SYS_BAUDRATE_TABLE:
2678		List of legal baudrate settings for this board.
2679
2680- CONFIG_SYS_CONSOLE_INFO_QUIET
2681		Suppress display of console information at boot.
2682
2683- CONFIG_SYS_CONSOLE_IS_IN_ENV
2684		If the board specific function
2685			extern int overwrite_console (void);
2686		returns 1, the stdin, stderr and stdout are switched to the
2687		serial port, else the settings in the environment are used.
2688
2689- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2690		Enable the call to overwrite_console().
2691
2692- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2693		Enable overwrite of previous console environment settings.
2694
2695- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2696		Begin and End addresses of the area used by the
2697		simple memory test.
2698
2699- CONFIG_SYS_ALT_MEMTEST:
2700		Enable an alternate, more extensive memory test.
2701
2702- CONFIG_SYS_MEMTEST_SCRATCH:
2703		Scratch address used by the alternate memory test
2704		You only need to set this if address zero isn't writeable
2705
2706- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2707		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2708		this specified memory area will get subtracted from the top
2709		(end) of RAM and won't get "touched" at all by U-Boot. By
2710		fixing up gd->ram_size the Linux kernel should gets passed
2711		the now "corrected" memory size and won't touch it either.
2712		This should work for arch/ppc and arch/powerpc. Only Linux
2713		board ports in arch/powerpc with bootwrapper support that
2714		recalculate the memory size from the SDRAM controller setup
2715		will have to get fixed in Linux additionally.
2716
2717		This option can be used as a workaround for the 440EPx/GRx
2718		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2719		be touched.
2720
2721		WARNING: Please make sure that this value is a multiple of
2722		the Linux page size (normally 4k). If this is not the case,
2723		then the end address of the Linux memory will be located at a
2724		non page size aligned address and this could cause major
2725		problems.
2726
2727- CONFIG_SYS_TFTP_LOADADDR:
2728		Default load address for network file downloads
2729
2730- CONFIG_SYS_LOADS_BAUD_CHANGE:
2731		Enable temporary baudrate change while serial download
2732
2733- CONFIG_SYS_SDRAM_BASE:
2734		Physical start address of SDRAM. _Must_ be 0 here.
2735
2736- CONFIG_SYS_MBIO_BASE:
2737		Physical start address of Motherboard I/O (if using a
2738		Cogent motherboard)
2739
2740- CONFIG_SYS_FLASH_BASE:
2741		Physical start address of Flash memory.
2742
2743- CONFIG_SYS_MONITOR_BASE:
2744		Physical start address of boot monitor code (set by
2745		make config files to be same as the text base address
2746		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2747		CONFIG_SYS_FLASH_BASE when booting from flash.
2748
2749- CONFIG_SYS_MONITOR_LEN:
2750		Size of memory reserved for monitor code, used to
2751		determine _at_compile_time_ (!) if the environment is
2752		embedded within the U-Boot image, or in a separate
2753		flash sector.
2754
2755- CONFIG_SYS_MALLOC_LEN:
2756		Size of DRAM reserved for malloc() use.
2757
2758- CONFIG_SYS_BOOTM_LEN:
2759		Normally compressed uImages are limited to an
2760		uncompressed size of 8 MBytes. If this is not enough,
2761		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2762		to adjust this setting to your needs.
2763
2764- CONFIG_SYS_BOOTMAPSZ:
2765		Maximum size of memory mapped by the startup code of
2766		the Linux kernel; all data that must be processed by
2767		the Linux kernel (bd_info, boot arguments, FDT blob if
2768		used) must be put below this limit, unless "bootm_low"
2769		enviroment variable is defined and non-zero. In such case
2770		all data for the Linux kernel must be between "bootm_low"
2771		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2772		variable "bootm_mapsize" will override the value of
2773		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2774		then the value in "bootm_size" will be used instead.
2775
2776- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2777		Enable initrd_high functionality.  If defined then the
2778		initrd_high feature is enabled and the bootm ramdisk subcommand
2779		is enabled.
2780
2781- CONFIG_SYS_BOOT_GET_CMDLINE:
2782		Enables allocating and saving kernel cmdline in space between
2783		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2784
2785- CONFIG_SYS_BOOT_GET_KBD:
2786		Enables allocating and saving a kernel copy of the bd_info in
2787		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2788
2789- CONFIG_SYS_MAX_FLASH_BANKS:
2790		Max number of Flash memory banks
2791
2792- CONFIG_SYS_MAX_FLASH_SECT:
2793		Max number of sectors on a Flash chip
2794
2795- CONFIG_SYS_FLASH_ERASE_TOUT:
2796		Timeout for Flash erase operations (in ms)
2797
2798- CONFIG_SYS_FLASH_WRITE_TOUT:
2799		Timeout for Flash write operations (in ms)
2800
2801- CONFIG_SYS_FLASH_LOCK_TOUT
2802		Timeout for Flash set sector lock bit operation (in ms)
2803
2804- CONFIG_SYS_FLASH_UNLOCK_TOUT
2805		Timeout for Flash clear lock bits operation (in ms)
2806
2807- CONFIG_SYS_FLASH_PROTECTION
2808		If defined, hardware flash sectors protection is used
2809		instead of U-Boot software protection.
2810
2811- CONFIG_SYS_DIRECT_FLASH_TFTP:
2812
2813		Enable TFTP transfers directly to flash memory;
2814		without this option such a download has to be
2815		performed in two steps: (1) download to RAM, and (2)
2816		copy from RAM to flash.
2817
2818		The two-step approach is usually more reliable, since
2819		you can check if the download worked before you erase
2820		the flash, but in some situations (when system RAM is
2821		too limited to allow for a temporary copy of the
2822		downloaded image) this option may be very useful.
2823
2824- CONFIG_SYS_FLASH_CFI:
2825		Define if the flash driver uses extra elements in the
2826		common flash structure for storing flash geometry.
2827
2828- CONFIG_FLASH_CFI_DRIVER
2829		This option also enables the building of the cfi_flash driver
2830		in the drivers directory
2831
2832- CONFIG_FLASH_CFI_MTD
2833		This option enables the building of the cfi_mtd driver
2834		in the drivers directory. The driver exports CFI flash
2835		to the MTD layer.
2836
2837- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2838		Use buffered writes to flash.
2839
2840- CONFIG_FLASH_SPANSION_S29WS_N
2841		s29ws-n MirrorBit flash has non-standard addresses for buffered
2842		write commands.
2843
2844- CONFIG_SYS_FLASH_QUIET_TEST
2845		If this option is defined, the common CFI flash doesn't
2846		print it's warning upon not recognized FLASH banks. This
2847		is useful, if some of the configured banks are only
2848		optionally available.
2849
2850- CONFIG_FLASH_SHOW_PROGRESS
2851		If defined (must be an integer), print out countdown
2852		digits and dots.  Recommended value: 45 (9..1) for 80
2853		column displays, 15 (3..1) for 40 column displays.
2854
2855- CONFIG_SYS_RX_ETH_BUFFER:
2856		Defines the number of Ethernet receive buffers. On some
2857		Ethernet controllers it is recommended to set this value
2858		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2859		buffers can be full shortly after enabling the interface
2860		on high Ethernet traffic.
2861		Defaults to 4 if not defined.
2862
2863- CONFIG_ENV_MAX_ENTRIES
2864
2865	Maximum number of entries in the hash table that is used
2866	internally to store the environment settings. The default
2867	setting is supposed to be generous and should work in most
2868	cases. This setting can be used to tune behaviour; see
2869	lib/hashtable.c for details.
2870
2871The following definitions that deal with the placement and management
2872of environment data (variable area); in general, we support the
2873following configurations:
2874
2875- CONFIG_BUILD_ENVCRC:
2876
2877	Builds up envcrc with the target environment so that external utils
2878	may easily extract it and embed it in final U-Boot images.
2879
2880- CONFIG_ENV_IS_IN_FLASH:
2881
2882	Define this if the environment is in flash memory.
2883
2884	a) The environment occupies one whole flash sector, which is
2885	   "embedded" in the text segment with the U-Boot code. This
2886	   happens usually with "bottom boot sector" or "top boot
2887	   sector" type flash chips, which have several smaller
2888	   sectors at the start or the end. For instance, such a
2889	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2890	   such a case you would place the environment in one of the
2891	   4 kB sectors - with U-Boot code before and after it. With
2892	   "top boot sector" type flash chips, you would put the
2893	   environment in one of the last sectors, leaving a gap
2894	   between U-Boot and the environment.
2895
2896	- CONFIG_ENV_OFFSET:
2897
2898	   Offset of environment data (variable area) to the
2899	   beginning of flash memory; for instance, with bottom boot
2900	   type flash chips the second sector can be used: the offset
2901	   for this sector is given here.
2902
2903	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2904
2905	- CONFIG_ENV_ADDR:
2906
2907	   This is just another way to specify the start address of
2908	   the flash sector containing the environment (instead of
2909	   CONFIG_ENV_OFFSET).
2910
2911	- CONFIG_ENV_SECT_SIZE:
2912
2913	   Size of the sector containing the environment.
2914
2915
2916	b) Sometimes flash chips have few, equal sized, BIG sectors.
2917	   In such a case you don't want to spend a whole sector for
2918	   the environment.
2919
2920	- CONFIG_ENV_SIZE:
2921
2922	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2923	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2924	   of this flash sector for the environment. This saves
2925	   memory for the RAM copy of the environment.
2926
2927	   It may also save flash memory if you decide to use this
2928	   when your environment is "embedded" within U-Boot code,
2929	   since then the remainder of the flash sector could be used
2930	   for U-Boot code. It should be pointed out that this is
2931	   STRONGLY DISCOURAGED from a robustness point of view:
2932	   updating the environment in flash makes it always
2933	   necessary to erase the WHOLE sector. If something goes
2934	   wrong before the contents has been restored from a copy in
2935	   RAM, your target system will be dead.
2936
2937	- CONFIG_ENV_ADDR_REDUND
2938	  CONFIG_ENV_SIZE_REDUND
2939
2940	   These settings describe a second storage area used to hold
2941	   a redundant copy of the environment data, so that there is
2942	   a valid backup copy in case there is a power failure during
2943	   a "saveenv" operation.
2944
2945BE CAREFUL! Any changes to the flash layout, and some changes to the
2946source code will make it necessary to adapt <board>/u-boot.lds*
2947accordingly!
2948
2949
2950- CONFIG_ENV_IS_IN_NVRAM:
2951
2952	Define this if you have some non-volatile memory device
2953	(NVRAM, battery buffered SRAM) which you want to use for the
2954	environment.
2955
2956	- CONFIG_ENV_ADDR:
2957	- CONFIG_ENV_SIZE:
2958
2959	  These two #defines are used to determine the memory area you
2960	  want to use for environment. It is assumed that this memory
2961	  can just be read and written to, without any special
2962	  provision.
2963
2964BE CAREFUL! The first access to the environment happens quite early
2965in U-Boot initalization (when we try to get the setting of for the
2966console baudrate). You *MUST* have mapped your NVRAM area then, or
2967U-Boot will hang.
2968
2969Please note that even with NVRAM we still use a copy of the
2970environment in RAM: we could work on NVRAM directly, but we want to
2971keep settings there always unmodified except somebody uses "saveenv"
2972to save the current settings.
2973
2974
2975- CONFIG_ENV_IS_IN_EEPROM:
2976
2977	Use this if you have an EEPROM or similar serial access
2978	device and a driver for it.
2979
2980	- CONFIG_ENV_OFFSET:
2981	- CONFIG_ENV_SIZE:
2982
2983	  These two #defines specify the offset and size of the
2984	  environment area within the total memory of your EEPROM.
2985
2986	- CONFIG_SYS_I2C_EEPROM_ADDR:
2987	  If defined, specified the chip address of the EEPROM device.
2988	  The default address is zero.
2989
2990	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2991	  If defined, the number of bits used to address bytes in a
2992	  single page in the EEPROM device.  A 64 byte page, for example
2993	  would require six bits.
2994
2995	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2996	  If defined, the number of milliseconds to delay between
2997	  page writes.	The default is zero milliseconds.
2998
2999	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
3000	  The length in bytes of the EEPROM memory array address.  Note
3001	  that this is NOT the chip address length!
3002
3003	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
3004	  EEPROM chips that implement "address overflow" are ones
3005	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
3006	  address and the extra bits end up in the "chip address" bit
3007	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
3008	  byte chips.
3009
3010	  Note that we consider the length of the address field to
3011	  still be one byte because the extra address bits are hidden
3012	  in the chip address.
3013
3014	- CONFIG_SYS_EEPROM_SIZE:
3015	  The size in bytes of the EEPROM device.
3016
3017	- CONFIG_ENV_EEPROM_IS_ON_I2C
3018	  define this, if you have I2C and SPI activated, and your
3019	  EEPROM, which holds the environment, is on the I2C bus.
3020
3021	- CONFIG_I2C_ENV_EEPROM_BUS
3022	  if you have an Environment on an EEPROM reached over
3023	  I2C muxes, you can define here, how to reach this
3024	  EEPROM. For example:
3025
3026	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
3027
3028	  EEPROM which holds the environment, is reached over
3029	  a pca9547 i2c mux with address 0x70, channel 3.
3030
3031- CONFIG_ENV_IS_IN_DATAFLASH:
3032
3033	Define this if you have a DataFlash memory device which you
3034	want to use for the environment.
3035
3036	- CONFIG_ENV_OFFSET:
3037	- CONFIG_ENV_ADDR:
3038	- CONFIG_ENV_SIZE:
3039
3040	  These three #defines specify the offset and size of the
3041	  environment area within the total memory of your DataFlash placed
3042	  at the specified address.
3043
3044- CONFIG_ENV_IS_IN_REMOTE:
3045
3046	Define this if you have a remote memory space which you
3047	want to use for the local device's environment.
3048
3049	- CONFIG_ENV_ADDR:
3050	- CONFIG_ENV_SIZE:
3051
3052	  These two #defines specify the address and size of the
3053	  environment area within the remote memory space. The
3054	  local device can get the environment from remote memory
3055	  space by SRIO or other links.
3056
3057BE CAREFUL! For some special cases, the local device can not use
3058"saveenv" command. For example, the local device will get the
3059environment stored in a remote NOR flash by SRIO link, but it can
3060not erase, write this NOR flash by SRIO interface.
3061
3062- CONFIG_ENV_IS_IN_NAND:
3063
3064	Define this if you have a NAND device which you want to use
3065	for the environment.
3066
3067	- CONFIG_ENV_OFFSET:
3068	- CONFIG_ENV_SIZE:
3069
3070	  These two #defines specify the offset and size of the environment
3071	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
3072	  aligned to an erase block boundary.
3073
3074	- CONFIG_ENV_OFFSET_REDUND (optional):
3075
3076	  This setting describes a second storage area of CONFIG_ENV_SIZE
3077	  size used to hold a redundant copy of the environment data, so
3078	  that there is a valid backup copy in case there is a power failure
3079	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
3080	  aligned to an erase block boundary.
3081
3082	- CONFIG_ENV_RANGE (optional):
3083
3084	  Specifies the length of the region in which the environment
3085	  can be written.  This should be a multiple of the NAND device's
3086	  block size.  Specifying a range with more erase blocks than
3087	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
3088	  the range to be avoided.
3089
3090	- CONFIG_ENV_OFFSET_OOB (optional):
3091
3092	  Enables support for dynamically retrieving the offset of the
3093	  environment from block zero's out-of-band data.  The
3094	  "nand env.oob" command can be used to record this offset.
3095	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
3096	  using CONFIG_ENV_OFFSET_OOB.
3097
3098- CONFIG_NAND_ENV_DST
3099
3100	Defines address in RAM to which the nand_spl code should copy the
3101	environment. If redundant environment is used, it will be copied to
3102	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3103
3104- CONFIG_SYS_SPI_INIT_OFFSET
3105
3106	Defines offset to the initial SPI buffer area in DPRAM. The
3107	area is used at an early stage (ROM part) if the environment
3108	is configured to reside in the SPI EEPROM: We need a 520 byte
3109	scratch DPRAM area. It is used between the two initialization
3110	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3111	to be a good choice since it makes it far enough from the
3112	start of the data area as well as from the stack pointer.
3113
3114Please note that the environment is read-only until the monitor
3115has been relocated to RAM and a RAM copy of the environment has been
3116created; also, when using EEPROM you will have to use getenv_f()
3117until then to read environment variables.
3118
3119The environment is protected by a CRC32 checksum. Before the monitor
3120is relocated into RAM, as a result of a bad CRC you will be working
3121with the compiled-in default environment - *silently*!!! [This is
3122necessary, because the first environment variable we need is the
3123"baudrate" setting for the console - if we have a bad CRC, we don't
3124have any device yet where we could complain.]
3125
3126Note: once the monitor has been relocated, then it will complain if
3127the default environment is used; a new CRC is computed as soon as you
3128use the "saveenv" command to store a valid environment.
3129
3130- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3131		Echo the inverted Ethernet link state to the fault LED.
3132
3133		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3134		      also needs to be defined.
3135
3136- CONFIG_SYS_FAULT_MII_ADDR:
3137		MII address of the PHY to check for the Ethernet link state.
3138
3139- CONFIG_NS16550_MIN_FUNCTIONS:
3140		Define this if you desire to only have use of the NS16550_init
3141		and NS16550_putc functions for the serial driver located at
3142		drivers/serial/ns16550.c.  This option is useful for saving
3143		space for already greatly restricted images, including but not
3144		limited to NAND_SPL configurations.
3145
3146Low Level (hardware related) configuration options:
3147---------------------------------------------------
3148
3149- CONFIG_SYS_CACHELINE_SIZE:
3150		Cache Line Size of the CPU.
3151
3152- CONFIG_SYS_DEFAULT_IMMR:
3153		Default address of the IMMR after system reset.
3154
3155		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3156		and RPXsuper) to be able to adjust the position of
3157		the IMMR register after a reset.
3158
3159- CONFIG_SYS_CCSRBAR_DEFAULT:
3160		Default (power-on reset) physical address of CCSR on Freescale
3161		PowerPC SOCs.
3162
3163- CONFIG_SYS_CCSRBAR:
3164		Virtual address of CCSR.  On a 32-bit build, this is typically
3165		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3166
3167		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3168		for cross-platform code that uses that macro instead.
3169
3170- CONFIG_SYS_CCSRBAR_PHYS:
3171		Physical address of CCSR.  CCSR can be relocated to a new
3172		physical address, if desired.  In this case, this macro should
3173		be set to that address.	 Otherwise, it should be set to the
3174		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3175		is typically relocated on 36-bit builds.  It is recommended
3176		that this macro be defined via the _HIGH and _LOW macros:
3177
3178		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3179			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3180
3181- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3182		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3183		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3184		used in assembly code, so it must not contain typecasts or
3185		integer size suffixes (e.g. "ULL").
3186
3187- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3188		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3189		used in assembly code, so it must not contain typecasts or
3190		integer size suffixes (e.g. "ULL").
3191
3192- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3193		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3194		forced to a value that ensures that CCSR is not relocated.
3195
3196- Floppy Disk Support:
3197		CONFIG_SYS_FDC_DRIVE_NUMBER
3198
3199		the default drive number (default value 0)
3200
3201		CONFIG_SYS_ISA_IO_STRIDE
3202
3203		defines the spacing between FDC chipset registers
3204		(default value 1)
3205
3206		CONFIG_SYS_ISA_IO_OFFSET
3207
3208		defines the offset of register from address. It
3209		depends on which part of the data bus is connected to
3210		the FDC chipset. (default value 0)
3211
3212		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3213		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3214		default value.
3215
3216		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3217		fdc_hw_init() is called at the beginning of the FDC
3218		setup. fdc_hw_init() must be provided by the board
3219		source code. It is used to make hardware dependant
3220		initializations.
3221
3222- CONFIG_IDE_AHB:
3223		Most IDE controllers were designed to be connected with PCI
3224		interface. Only few of them were designed for AHB interface.
3225		When software is doing ATA command and data transfer to
3226		IDE devices through IDE-AHB controller, some additional
3227		registers accessing to these kind of IDE-AHB controller
3228		is requierd.
3229
3230- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3231		DO NOT CHANGE unless you know exactly what you're
3232		doing! (11-4) [MPC8xx/82xx systems only]
3233
3234- CONFIG_SYS_INIT_RAM_ADDR:
3235
3236		Start address of memory area that can be used for
3237		initial data and stack; please note that this must be
3238		writable memory that is working WITHOUT special
3239		initialization, i. e. you CANNOT use normal RAM which
3240		will become available only after programming the
3241		memory controller and running certain initialization
3242		sequences.
3243
3244		U-Boot uses the following memory types:
3245		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3246		- MPC824X: data cache
3247		- PPC4xx:  data cache
3248
3249- CONFIG_SYS_GBL_DATA_OFFSET:
3250
3251		Offset of the initial data structure in the memory
3252		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3253		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3254		data is located at the end of the available space
3255		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3256		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3257		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3258		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3259
3260	Note:
3261		On the MPC824X (or other systems that use the data
3262		cache for initial memory) the address chosen for
3263		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3264		point to an otherwise UNUSED address space between
3265		the top of RAM and the start of the PCI space.
3266
3267- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3268
3269- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3270
3271- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3272
3273- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3274
3275- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3276
3277- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3278
3279- CONFIG_SYS_OR_TIMING_SDRAM:
3280		SDRAM timing
3281
3282- CONFIG_SYS_MAMR_PTA:
3283		periodic timer for refresh
3284
3285- CONFIG_SYS_DER:	Debug Event Register (37-47)
3286
3287- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3288  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3289  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3290  CONFIG_SYS_BR1_PRELIM:
3291		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3292
3293- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3294  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3295  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3296		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3297
3298- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3299  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3300		Machine Mode Register and Memory Periodic Timer
3301		Prescaler definitions (SDRAM timing)
3302
3303- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3304		enable I2C microcode relocation patch (MPC8xx);
3305		define relocation offset in DPRAM [DSP2]
3306
3307- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3308		enable SMC microcode relocation patch (MPC8xx);
3309		define relocation offset in DPRAM [SMC1]
3310
3311- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3312		enable SPI microcode relocation patch (MPC8xx);
3313		define relocation offset in DPRAM [SCC4]
3314
3315- CONFIG_SYS_USE_OSCCLK:
3316		Use OSCM clock mode on MBX8xx board. Be careful,
3317		wrong setting might damage your board. Read
3318		doc/README.MBX before setting this variable!
3319
3320- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3321		Offset of the bootmode word in DPRAM used by post
3322		(Power On Self Tests). This definition overrides
3323		#define'd default value in commproc.h resp.
3324		cpm_8260.h.
3325
3326- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3327  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3328  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3329  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3330  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3331  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3332  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3333  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3334		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3335
3336- CONFIG_PCI_DISABLE_PCIE:
3337		Disable PCI-Express on systems where it is supported but not
3338		required.
3339
3340- CONFIG_SYS_SRIO:
3341		Chip has SRIO or not
3342
3343- CONFIG_SRIO1:
3344		Board has SRIO 1 port available
3345
3346- CONFIG_SRIO2:
3347		Board has SRIO 2 port available
3348
3349- CONFIG_SYS_SRIOn_MEM_VIRT:
3350		Virtual Address of SRIO port 'n' memory region
3351
3352- CONFIG_SYS_SRIOn_MEM_PHYS:
3353		Physical Address of SRIO port 'n' memory region
3354
3355- CONFIG_SYS_SRIOn_MEM_SIZE:
3356		Size of SRIO port 'n' memory region
3357
3358- CONFIG_SYS_NDFC_16
3359		Defined to tell the NDFC that the NAND chip is using a
3360		16 bit bus.
3361
3362- CONFIG_SYS_NDFC_EBC0_CFG
3363		Sets the EBC0_CFG register for the NDFC. If not defined
3364		a default value will be used.
3365
3366- CONFIG_SPD_EEPROM
3367		Get DDR timing information from an I2C EEPROM. Common
3368		with pluggable memory modules such as SODIMMs
3369
3370  SPD_EEPROM_ADDRESS
3371		I2C address of the SPD EEPROM
3372
3373- CONFIG_SYS_SPD_BUS_NUM
3374		If SPD EEPROM is on an I2C bus other than the first
3375		one, specify here. Note that the value must resolve
3376		to something your driver can deal with.
3377
3378- CONFIG_SYS_DDR_RAW_TIMING
3379		Get DDR timing information from other than SPD. Common with
3380		soldered DDR chips onboard without SPD. DDR raw timing
3381		parameters are extracted from datasheet and hard-coded into
3382		header files or board specific files.
3383
3384- CONFIG_FSL_DDR_INTERACTIVE
3385		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3386
3387- CONFIG_SYS_83XX_DDR_USES_CS0
3388		Only for 83xx systems. If specified, then DDR should
3389		be configured using CS0 and CS1 instead of CS2 and CS3.
3390
3391- CONFIG_ETHER_ON_FEC[12]
3392		Define to enable FEC[12] on a 8xx series processor.
3393
3394- CONFIG_FEC[12]_PHY
3395		Define to the hardcoded PHY address which corresponds
3396		to the given FEC; i. e.
3397			#define CONFIG_FEC1_PHY 4
3398		means that the PHY with address 4 is connected to FEC1
3399
3400		When set to -1, means to probe for first available.
3401
3402- CONFIG_FEC[12]_PHY_NORXERR
3403		The PHY does not have a RXERR line (RMII only).
3404		(so program the FEC to ignore it).
3405
3406- CONFIG_RMII
3407		Enable RMII mode for all FECs.
3408		Note that this is a global option, we can't
3409		have one FEC in standard MII mode and another in RMII mode.
3410
3411- CONFIG_CRC32_VERIFY
3412		Add a verify option to the crc32 command.
3413		The syntax is:
3414
3415		=> crc32 -v <address> <count> <crc32>
3416
3417		Where address/count indicate a memory area
3418		and crc32 is the correct crc32 which the
3419		area should have.
3420
3421- CONFIG_LOOPW
3422		Add the "loopw" memory command. This only takes effect if
3423		the memory commands are activated globally (CONFIG_CMD_MEM).
3424
3425- CONFIG_MX_CYCLIC
3426		Add the "mdc" and "mwc" memory commands. These are cyclic
3427		"md/mw" commands.
3428		Examples:
3429
3430		=> mdc.b 10 4 500
3431		This command will print 4 bytes (10,11,12,13) each 500 ms.
3432
3433		=> mwc.l 100 12345678 10
3434		This command will write 12345678 to address 100 all 10 ms.
3435
3436		This only takes effect if the memory commands are activated
3437		globally (CONFIG_CMD_MEM).
3438
3439- CONFIG_SKIP_LOWLEVEL_INIT
3440		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3441		low level initializations (like setting up the memory
3442		controller) are omitted and/or U-Boot does not
3443		relocate itself into RAM.
3444
3445		Normally this variable MUST NOT be defined. The only
3446		exception is when U-Boot is loaded (to RAM) by some
3447		other boot loader or by a debugger which performs
3448		these initializations itself.
3449
3450- CONFIG_SPL_BUILD
3451		Modifies the behaviour of start.S when compiling a loader
3452		that is executed before the actual U-Boot. E.g. when
3453		compiling a NAND SPL.
3454
3455- CONFIG_USE_ARCH_MEMCPY
3456  CONFIG_USE_ARCH_MEMSET
3457		If these options are used a optimized version of memcpy/memset will
3458		be used if available. These functions may be faster under some
3459		conditions but may increase the binary size.
3460
3461Freescale QE/FMAN Firmware Support:
3462-----------------------------------
3463
3464The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3465loading of "firmware", which is encoded in the QE firmware binary format.
3466This firmware often needs to be loaded during U-Boot booting, so macros
3467are used to identify the storage device (NOR flash, SPI, etc) and the address
3468within that device.
3469
3470- CONFIG_SYS_QE_FMAN_FW_ADDR
3471	The address in the storage device where the firmware is located.  The
3472	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3473	is also specified.
3474
3475- CONFIG_SYS_QE_FMAN_FW_LENGTH
3476	The maximum possible size of the firmware.  The firmware binary format
3477	has a field that specifies the actual size of the firmware, but it
3478	might not be possible to read any part of the firmware unless some
3479	local storage is allocated to hold the entire firmware first.
3480
3481- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3482	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3483	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3484	virtual address in NOR flash.
3485
3486- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3487	Specifies that QE/FMAN firmware is located in NAND flash.
3488	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3489
3490- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3491	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3492	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3493
3494- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3495	Specifies that QE/FMAN firmware is located on the primary SPI
3496	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3497
3498- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
3499	Specifies that QE/FMAN firmware is located in the remote (master)
3500	memory space.	CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
3501	can be mapped from slave TLB->slave LAW->slave SRIO outbound window
3502	->master inbound window->master LAW->the ucode address in master's
3503	NOR flash.
3504
3505Building the Software:
3506======================
3507
3508Building U-Boot has been tested in several native build environments
3509and in many different cross environments. Of course we cannot support
3510all possibly existing versions of cross development tools in all
3511(potentially obsolete) versions. In case of tool chain problems we
3512recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3513which is extensively used to build and test U-Boot.
3514
3515If you are not using a native environment, it is assumed that you
3516have GNU cross compiling tools available in your path. In this case,
3517you must set the environment variable CROSS_COMPILE in your shell.
3518Note that no changes to the Makefile or any other source files are
3519necessary. For example using the ELDK on a 4xx CPU, please enter:
3520
3521	$ CROSS_COMPILE=ppc_4xx-
3522	$ export CROSS_COMPILE
3523
3524Note: If you wish to generate Windows versions of the utilities in
3525      the tools directory you can use the MinGW toolchain
3526      (http://www.mingw.org).  Set your HOST tools to the MinGW
3527      toolchain and execute 'make tools'.  For example:
3528
3529       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3530
3531      Binaries such as tools/mkimage.exe will be created which can
3532      be executed on computers running Windows.
3533
3534U-Boot is intended to be simple to build. After installing the
3535sources you must configure U-Boot for one specific board type. This
3536is done by typing:
3537
3538	make NAME_config
3539
3540where "NAME_config" is the name of one of the existing configu-
3541rations; see boards.cfg for supported names.
3542
3543Note: for some board special configuration names may exist; check if
3544      additional information is available from the board vendor; for
3545      instance, the TQM823L systems are available without (standard)
3546      or with LCD support. You can select such additional "features"
3547      when choosing the configuration, i. e.
3548
3549      make TQM823L_config
3550	- will configure for a plain TQM823L, i. e. no LCD support
3551
3552      make TQM823L_LCD_config
3553	- will configure for a TQM823L with U-Boot console on LCD
3554
3555      etc.
3556
3557
3558Finally, type "make all", and you should get some working U-Boot
3559images ready for download to / installation on your system:
3560
3561- "u-boot.bin" is a raw binary image
3562- "u-boot" is an image in ELF binary format
3563- "u-boot.srec" is in Motorola S-Record format
3564
3565By default the build is performed locally and the objects are saved
3566in the source directory. One of the two methods can be used to change
3567this behavior and build U-Boot to some external directory:
3568
35691. Add O= to the make command line invocations:
3570
3571	make O=/tmp/build distclean
3572	make O=/tmp/build NAME_config
3573	make O=/tmp/build all
3574
35752. Set environment variable BUILD_DIR to point to the desired location:
3576
3577	export BUILD_DIR=/tmp/build
3578	make distclean
3579	make NAME_config
3580	make all
3581
3582Note that the command line "O=" setting overrides the BUILD_DIR environment
3583variable.
3584
3585
3586Please be aware that the Makefiles assume you are using GNU make, so
3587for instance on NetBSD you might need to use "gmake" instead of
3588native "make".
3589
3590
3591If the system board that you have is not listed, then you will need
3592to port U-Boot to your hardware platform. To do this, follow these
3593steps:
3594
35951.  Add a new configuration option for your board to the toplevel
3596    "boards.cfg" file, using the existing entries as examples.
3597    Follow the instructions there to keep the boards in order.
35982.  Create a new directory to hold your board specific code. Add any
3599    files you need. In your board directory, you will need at least
3600    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
36013.  Create a new configuration file "include/configs/<board>.h" for
3602    your board
36033.  If you're porting U-Boot to a new CPU, then also create a new
3604    directory to hold your CPU specific code. Add any files you need.
36054.  Run "make <board>_config" with your new name.
36065.  Type "make", and you should get a working "u-boot.srec" file
3607    to be installed on your target system.
36086.  Debug and solve any problems that might arise.
3609    [Of course, this last step is much harder than it sounds.]
3610
3611
3612Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3613==============================================================
3614
3615If you have modified U-Boot sources (for instance added a new board
3616or support for new devices, a new CPU, etc.) you are expected to
3617provide feedback to the other developers. The feedback normally takes
3618the form of a "patch", i. e. a context diff against a certain (latest
3619official or latest in the git repository) version of U-Boot sources.
3620
3621But before you submit such a patch, please verify that your modifi-
3622cation did not break existing code. At least make sure that *ALL* of
3623the supported boards compile WITHOUT ANY compiler warnings. To do so,
3624just run the "MAKEALL" script, which will configure and build U-Boot
3625for ALL supported system. Be warned, this will take a while. You can
3626select which (cross) compiler to use by passing a `CROSS_COMPILE'
3627environment variable to the script, i. e. to use the ELDK cross tools
3628you can type
3629
3630	CROSS_COMPILE=ppc_8xx- MAKEALL
3631
3632or to build on a native PowerPC system you can type
3633
3634	CROSS_COMPILE=' ' MAKEALL
3635
3636When using the MAKEALL script, the default behaviour is to build
3637U-Boot in the source directory. This location can be changed by
3638setting the BUILD_DIR environment variable. Also, for each target
3639built, the MAKEALL script saves two log files (<target>.ERR and
3640<target>.MAKEALL) in the <source dir>/LOG directory. This default
3641location can be changed by setting the MAKEALL_LOGDIR environment
3642variable. For example:
3643
3644	export BUILD_DIR=/tmp/build
3645	export MAKEALL_LOGDIR=/tmp/log
3646	CROSS_COMPILE=ppc_8xx- MAKEALL
3647
3648With the above settings build objects are saved in the /tmp/build,
3649log files are saved in the /tmp/log and the source tree remains clean
3650during the whole build process.
3651
3652
3653See also "U-Boot Porting Guide" below.
3654
3655
3656Monitor Commands - Overview:
3657============================
3658
3659go	- start application at address 'addr'
3660run	- run commands in an environment variable
3661bootm	- boot application image from memory
3662bootp	- boot image via network using BootP/TFTP protocol
3663bootz   - boot zImage from memory
3664tftpboot- boot image via network using TFTP protocol
3665	       and env variables "ipaddr" and "serverip"
3666	       (and eventually "gatewayip")
3667tftpput - upload a file via network using TFTP protocol
3668rarpboot- boot image via network using RARP/TFTP protocol
3669diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3670loads	- load S-Record file over serial line
3671loadb	- load binary file over serial line (kermit mode)
3672md	- memory display
3673mm	- memory modify (auto-incrementing)
3674nm	- memory modify (constant address)
3675mw	- memory write (fill)
3676cp	- memory copy
3677cmp	- memory compare
3678crc32	- checksum calculation
3679i2c	- I2C sub-system
3680sspi	- SPI utility commands
3681base	- print or set address offset
3682printenv- print environment variables
3683setenv	- set environment variables
3684saveenv - save environment variables to persistent storage
3685protect - enable or disable FLASH write protection
3686erase	- erase FLASH memory
3687flinfo	- print FLASH memory information
3688bdinfo	- print Board Info structure
3689iminfo	- print header information for application image
3690coninfo - print console devices and informations
3691ide	- IDE sub-system
3692loop	- infinite loop on address range
3693loopw	- infinite write loop on address range
3694mtest	- simple RAM test
3695icache	- enable or disable instruction cache
3696dcache	- enable or disable data cache
3697reset	- Perform RESET of the CPU
3698echo	- echo args to console
3699version - print monitor version
3700help	- print online help
3701?	- alias for 'help'
3702
3703
3704Monitor Commands - Detailed Description:
3705========================================
3706
3707TODO.
3708
3709For now: just type "help <command>".
3710
3711
3712Environment Variables:
3713======================
3714
3715U-Boot supports user configuration using Environment Variables which
3716can be made persistent by saving to Flash memory.
3717
3718Environment Variables are set using "setenv", printed using
3719"printenv", and saved to Flash using "saveenv". Using "setenv"
3720without a value can be used to delete a variable from the
3721environment. As long as you don't save the environment you are
3722working with an in-memory copy. In case the Flash area containing the
3723environment is erased by accident, a default environment is provided.
3724
3725Some configuration options can be set using Environment Variables.
3726
3727List of environment variables (most likely not complete):
3728
3729  baudrate	- see CONFIG_BAUDRATE
3730
3731  bootdelay	- see CONFIG_BOOTDELAY
3732
3733  bootcmd	- see CONFIG_BOOTCOMMAND
3734
3735  bootargs	- Boot arguments when booting an RTOS image
3736
3737  bootfile	- Name of the image to load with TFTP
3738
3739  bootm_low	- Memory range available for image processing in the bootm
3740		  command can be restricted. This variable is given as
3741		  a hexadecimal number and defines lowest address allowed
3742		  for use by the bootm command. See also "bootm_size"
3743		  environment variable. Address defined by "bootm_low" is
3744		  also the base of the initial memory mapping for the Linux
3745		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3746		  bootm_mapsize.
3747
3748  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3749		  This variable is given as a hexadecimal number and it
3750		  defines the size of the memory region starting at base
3751		  address bootm_low that is accessible by the Linux kernel
3752		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3753		  as the default value if it is defined, and bootm_size is
3754		  used otherwise.
3755
3756  bootm_size	- Memory range available for image processing in the bootm
3757		  command can be restricted. This variable is given as
3758		  a hexadecimal number and defines the size of the region
3759		  allowed for use by the bootm command. See also "bootm_low"
3760		  environment variable.
3761
3762  updatefile	- Location of the software update file on a TFTP server, used
3763		  by the automatic software update feature. Please refer to
3764		  documentation in doc/README.update for more details.
3765
3766  autoload	- if set to "no" (any string beginning with 'n'),
3767		  "bootp" will just load perform a lookup of the
3768		  configuration from the BOOTP server, but not try to
3769		  load any image using TFTP
3770
3771  autostart	- if set to "yes", an image loaded using the "bootp",
3772		  "rarpboot", "tftpboot" or "diskboot" commands will
3773		  be automatically started (by internally calling
3774		  "bootm")
3775
3776		  If set to "no", a standalone image passed to the
3777		  "bootm" command will be copied to the load address
3778		  (and eventually uncompressed), but NOT be started.
3779		  This can be used to load and uncompress arbitrary
3780		  data.
3781
3782  fdt_high	- if set this restricts the maximum address that the
3783		  flattened device tree will be copied into upon boot.
3784		  For example, if you have a system with 1 GB memory
3785		  at physical address 0x10000000, while Linux kernel
3786		  only recognizes the first 704 MB as low memory, you
3787		  may need to set fdt_high as 0x3C000000 to have the
3788		  device tree blob be copied to the maximum address
3789		  of the 704 MB low memory, so that Linux kernel can
3790		  access it during the boot procedure.
3791
3792		  If this is set to the special value 0xFFFFFFFF then
3793		  the fdt will not be copied at all on boot.  For this
3794		  to work it must reside in writable memory, have
3795		  sufficient padding on the end of it for u-boot to
3796		  add the information it needs into it, and the memory
3797		  must be accessible by the kernel.
3798
3799  fdtcontroladdr- if set this is the address of the control flattened
3800		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3801		  defined.
3802
3803  i2cfast	- (PPC405GP|PPC405EP only)
3804		  if set to 'y' configures Linux I2C driver for fast
3805		  mode (400kHZ). This environment variable is used in
3806		  initialization code. So, for changes to be effective
3807		  it must be saved and board must be reset.
3808
3809  initrd_high	- restrict positioning of initrd images:
3810		  If this variable is not set, initrd images will be
3811		  copied to the highest possible address in RAM; this
3812		  is usually what you want since it allows for
3813		  maximum initrd size. If for some reason you want to
3814		  make sure that the initrd image is loaded below the
3815		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3816		  variable to a value of "no" or "off" or "0".
3817		  Alternatively, you can set it to a maximum upper
3818		  address to use (U-Boot will still check that it
3819		  does not overwrite the U-Boot stack and data).
3820
3821		  For instance, when you have a system with 16 MB
3822		  RAM, and want to reserve 4 MB from use by Linux,
3823		  you can do this by adding "mem=12M" to the value of
3824		  the "bootargs" variable. However, now you must make
3825		  sure that the initrd image is placed in the first
3826		  12 MB as well - this can be done with
3827
3828		  setenv initrd_high 00c00000
3829
3830		  If you set initrd_high to 0xFFFFFFFF, this is an
3831		  indication to U-Boot that all addresses are legal
3832		  for the Linux kernel, including addresses in flash
3833		  memory. In this case U-Boot will NOT COPY the
3834		  ramdisk at all. This may be useful to reduce the
3835		  boot time on your system, but requires that this
3836		  feature is supported by your Linux kernel.
3837
3838  ipaddr	- IP address; needed for tftpboot command
3839
3840  loadaddr	- Default load address for commands like "bootp",
3841		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3842
3843  loads_echo	- see CONFIG_LOADS_ECHO
3844
3845  serverip	- TFTP server IP address; needed for tftpboot command
3846
3847  bootretry	- see CONFIG_BOOT_RETRY_TIME
3848
3849  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3850
3851  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3852
3853  ethprime	- controls which interface is used first.
3854
3855  ethact	- controls which interface is currently active.
3856		  For example you can do the following
3857
3858		  => setenv ethact FEC
3859		  => ping 192.168.0.1 # traffic sent on FEC
3860		  => setenv ethact SCC
3861		  => ping 10.0.0.1 # traffic sent on SCC
3862
3863  ethrotate	- When set to "no" U-Boot does not go through all
3864		  available network interfaces.
3865		  It just stays at the currently selected interface.
3866
3867  netretry	- When set to "no" each network operation will
3868		  either succeed or fail without retrying.
3869		  When set to "once" the network operation will
3870		  fail when all the available network interfaces
3871		  are tried once without success.
3872		  Useful on scripts which control the retry operation
3873		  themselves.
3874
3875  npe_ucode	- set load address for the NPE microcode
3876
3877  tftpsrcport	- If this is set, the value is used for TFTP's
3878		  UDP source port.
3879
3880  tftpdstport	- If this is set, the value is used for TFTP's UDP
3881		  destination port instead of the Well Know Port 69.
3882
3883  tftpblocksize - Block size to use for TFTP transfers; if not set,
3884		  we use the TFTP server's default block size
3885
3886  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
3887		  seconds, minimum value is 1000 = 1 second). Defines
3888		  when a packet is considered to be lost so it has to
3889		  be retransmitted. The default is 5000 = 5 seconds.
3890		  Lowering this value may make downloads succeed
3891		  faster in networks with high packet loss rates or
3892		  with unreliable TFTP servers.
3893
3894  vlan		- When set to a value < 4095 the traffic over
3895		  Ethernet is encapsulated/received over 802.1q
3896		  VLAN tagged frames.
3897
3898The following image location variables contain the location of images
3899used in booting. The "Image" column gives the role of the image and is
3900not an environment variable name. The other columns are environment
3901variable names. "File Name" gives the name of the file on a TFTP
3902server, "RAM Address" gives the location in RAM the image will be
3903loaded to, and "Flash Location" gives the image's address in NOR
3904flash or offset in NAND flash.
3905
3906*Note* - these variables don't have to be defined for all boards, some
3907boards currenlty use other variables for these purposes, and some
3908boards use these variables for other purposes.
3909
3910Image		    File Name	     RAM Address       Flash Location
3911-----		    ---------	     -----------       --------------
3912u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
3913Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
3914device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
3915ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
3916
3917The following environment variables may be used and automatically
3918updated by the network boot commands ("bootp" and "rarpboot"),
3919depending the information provided by your boot server:
3920
3921  bootfile	- see above
3922  dnsip		- IP address of your Domain Name Server
3923  dnsip2	- IP address of your secondary Domain Name Server
3924  gatewayip	- IP address of the Gateway (Router) to use
3925  hostname	- Target hostname
3926  ipaddr	- see above
3927  netmask	- Subnet Mask
3928  rootpath	- Pathname of the root filesystem on the NFS server
3929  serverip	- see above
3930
3931
3932There are two special Environment Variables:
3933
3934  serial#	- contains hardware identification information such
3935		  as type string and/or serial number
3936  ethaddr	- Ethernet address
3937
3938These variables can be set only once (usually during manufacturing of
3939the board). U-Boot refuses to delete or overwrite these variables
3940once they have been set once.
3941
3942
3943Further special Environment Variables:
3944
3945  ver		- Contains the U-Boot version string as printed
3946		  with the "version" command. This variable is
3947		  readonly (see CONFIG_VERSION_VARIABLE).
3948
3949
3950Please note that changes to some configuration parameters may take
3951only effect after the next boot (yes, that's just like Windoze :-).
3952
3953
3954Command Line Parsing:
3955=====================
3956
3957There are two different command line parsers available with U-Boot:
3958the old "simple" one, and the much more powerful "hush" shell:
3959
3960Old, simple command line parser:
3961--------------------------------
3962
3963- supports environment variables (through setenv / saveenv commands)
3964- several commands on one line, separated by ';'
3965- variable substitution using "... ${name} ..." syntax
3966- special characters ('$', ';') can be escaped by prefixing with '\',
3967  for example:
3968	setenv bootcmd bootm \${address}
3969- You can also escape text by enclosing in single apostrophes, for example:
3970	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3971
3972Hush shell:
3973-----------
3974
3975- similar to Bourne shell, with control structures like
3976  if...then...else...fi, for...do...done; while...do...done,
3977  until...do...done, ...
3978- supports environment ("global") variables (through setenv / saveenv
3979  commands) and local shell variables (through standard shell syntax
3980  "name=value"); only environment variables can be used with "run"
3981  command
3982
3983General rules:
3984--------------
3985
3986(1) If a command line (or an environment variable executed by a "run"
3987    command) contains several commands separated by semicolon, and
3988    one of these commands fails, then the remaining commands will be
3989    executed anyway.
3990
3991(2) If you execute several variables with one call to run (i. e.
3992    calling run with a list of variables as arguments), any failing
3993    command will cause "run" to terminate, i. e. the remaining
3994    variables are not executed.
3995
3996Note for Redundant Ethernet Interfaces:
3997=======================================
3998
3999Some boards come with redundant Ethernet interfaces; U-Boot supports
4000such configurations and is capable of automatic selection of a
4001"working" interface when needed. MAC assignment works as follows:
4002
4003Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
4004MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
4005"eth1addr" (=>eth1), "eth2addr", ...
4006
4007If the network interface stores some valid MAC address (for instance
4008in SROM), this is used as default address if there is NO correspon-
4009ding setting in the environment; if the corresponding environment
4010variable is set, this overrides the settings in the card; that means:
4011
4012o If the SROM has a valid MAC address, and there is no address in the
4013  environment, the SROM's address is used.
4014
4015o If there is no valid address in the SROM, and a definition in the
4016  environment exists, then the value from the environment variable is
4017  used.
4018
4019o If both the SROM and the environment contain a MAC address, and
4020  both addresses are the same, this MAC address is used.
4021
4022o If both the SROM and the environment contain a MAC address, and the
4023  addresses differ, the value from the environment is used and a
4024  warning is printed.
4025
4026o If neither SROM nor the environment contain a MAC address, an error
4027  is raised.
4028
4029If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
4030will be programmed into hardware as part of the initialization process.	 This
4031may be skipped by setting the appropriate 'ethmacskip' environment variable.
4032The naming convention is as follows:
4033"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
4034
4035Image Formats:
4036==============
4037
4038U-Boot is capable of booting (and performing other auxiliary operations on)
4039images in two formats:
4040
4041New uImage format (FIT)
4042-----------------------
4043
4044Flexible and powerful format based on Flattened Image Tree -- FIT (similar
4045to Flattened Device Tree). It allows the use of images with multiple
4046components (several kernels, ramdisks, etc.), with contents protected by
4047SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
4048
4049
4050Old uImage format
4051-----------------
4052
4053Old image format is based on binary files which can be basically anything,
4054preceded by a special header; see the definitions in include/image.h for
4055details; basically, the header defines the following image properties:
4056
4057* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
4058  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
4059  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
4060  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
4061  INTEGRITY).
4062* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
4063  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
4064  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
4065* Compression Type (uncompressed, gzip, bzip2)
4066* Load Address
4067* Entry Point
4068* Image Name
4069* Image Timestamp
4070
4071The header is marked by a special Magic Number, and both the header
4072and the data portions of the image are secured against corruption by
4073CRC32 checksums.
4074
4075
4076Linux Support:
4077==============
4078
4079Although U-Boot should support any OS or standalone application
4080easily, the main focus has always been on Linux during the design of
4081U-Boot.
4082
4083U-Boot includes many features that so far have been part of some
4084special "boot loader" code within the Linux kernel. Also, any
4085"initrd" images to be used are no longer part of one big Linux image;
4086instead, kernel and "initrd" are separate images. This implementation
4087serves several purposes:
4088
4089- the same features can be used for other OS or standalone
4090  applications (for instance: using compressed images to reduce the
4091  Flash memory footprint)
4092
4093- it becomes much easier to port new Linux kernel versions because
4094  lots of low-level, hardware dependent stuff are done by U-Boot
4095
4096- the same Linux kernel image can now be used with different "initrd"
4097  images; of course this also means that different kernel images can
4098  be run with the same "initrd". This makes testing easier (you don't
4099  have to build a new "zImage.initrd" Linux image when you just
4100  change a file in your "initrd"). Also, a field-upgrade of the
4101  software is easier now.
4102
4103
4104Linux HOWTO:
4105============
4106
4107Porting Linux to U-Boot based systems:
4108---------------------------------------
4109
4110U-Boot cannot save you from doing all the necessary modifications to
4111configure the Linux device drivers for use with your target hardware
4112(no, we don't intend to provide a full virtual machine interface to
4113Linux :-).
4114
4115But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4116
4117Just make sure your machine specific header file (for instance
4118include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4119Information structure as we define in include/asm-<arch>/u-boot.h,
4120and make sure that your definition of IMAP_ADDR uses the same value
4121as your U-Boot configuration in CONFIG_SYS_IMMR.
4122
4123
4124Configuring the Linux kernel:
4125-----------------------------
4126
4127No specific requirements for U-Boot. Make sure you have some root
4128device (initial ramdisk, NFS) for your target system.
4129
4130
4131Building a Linux Image:
4132-----------------------
4133
4134With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4135not used. If you use recent kernel source, a new build target
4136"uImage" will exist which automatically builds an image usable by
4137U-Boot. Most older kernels also have support for a "pImage" target,
4138which was introduced for our predecessor project PPCBoot and uses a
4139100% compatible format.
4140
4141Example:
4142
4143	make TQM850L_config
4144	make oldconfig
4145	make dep
4146	make uImage
4147
4148The "uImage" build target uses a special tool (in 'tools/mkimage') to
4149encapsulate a compressed Linux kernel image with header	 information,
4150CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4151
4152* build a standard "vmlinux" kernel image (in ELF binary format):
4153
4154* convert the kernel into a raw binary image:
4155
4156	${CROSS_COMPILE}-objcopy -O binary \
4157				 -R .note -R .comment \
4158				 -S vmlinux linux.bin
4159
4160* compress the binary image:
4161
4162	gzip -9 linux.bin
4163
4164* package compressed binary image for U-Boot:
4165
4166	mkimage -A ppc -O linux -T kernel -C gzip \
4167		-a 0 -e 0 -n "Linux Kernel Image" \
4168		-d linux.bin.gz uImage
4169
4170
4171The "mkimage" tool can also be used to create ramdisk images for use
4172with U-Boot, either separated from the Linux kernel image, or
4173combined into one file. "mkimage" encapsulates the images with a 64
4174byte header containing information about target architecture,
4175operating system, image type, compression method, entry points, time
4176stamp, CRC32 checksums, etc.
4177
4178"mkimage" can be called in two ways: to verify existing images and
4179print the header information, or to build new images.
4180
4181In the first form (with "-l" option) mkimage lists the information
4182contained in the header of an existing U-Boot image; this includes
4183checksum verification:
4184
4185	tools/mkimage -l image
4186	  -l ==> list image header information
4187
4188The second form (with "-d" option) is used to build a U-Boot image
4189from a "data file" which is used as image payload:
4190
4191	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4192		      -n name -d data_file image
4193	  -A ==> set architecture to 'arch'
4194	  -O ==> set operating system to 'os'
4195	  -T ==> set image type to 'type'
4196	  -C ==> set compression type 'comp'
4197	  -a ==> set load address to 'addr' (hex)
4198	  -e ==> set entry point to 'ep' (hex)
4199	  -n ==> set image name to 'name'
4200	  -d ==> use image data from 'datafile'
4201
4202Right now, all Linux kernels for PowerPC systems use the same load
4203address (0x00000000), but the entry point address depends on the
4204kernel version:
4205
4206- 2.2.x kernels have the entry point at 0x0000000C,
4207- 2.3.x and later kernels have the entry point at 0x00000000.
4208
4209So a typical call to build a U-Boot image would read:
4210
4211	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4212	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4213	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4214	> examples/uImage.TQM850L
4215	Image Name:   2.4.4 kernel for TQM850L
4216	Created:      Wed Jul 19 02:34:59 2000
4217	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4218	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4219	Load Address: 0x00000000
4220	Entry Point:  0x00000000
4221
4222To verify the contents of the image (or check for corruption):
4223
4224	-> tools/mkimage -l examples/uImage.TQM850L
4225	Image Name:   2.4.4 kernel for TQM850L
4226	Created:      Wed Jul 19 02:34:59 2000
4227	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4228	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4229	Load Address: 0x00000000
4230	Entry Point:  0x00000000
4231
4232NOTE: for embedded systems where boot time is critical you can trade
4233speed for memory and install an UNCOMPRESSED image instead: this
4234needs more space in Flash, but boots much faster since it does not
4235need to be uncompressed:
4236
4237	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4238	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4239	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4240	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4241	> examples/uImage.TQM850L-uncompressed
4242	Image Name:   2.4.4 kernel for TQM850L
4243	Created:      Wed Jul 19 02:34:59 2000
4244	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4245	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4246	Load Address: 0x00000000
4247	Entry Point:  0x00000000
4248
4249
4250Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4251when your kernel is intended to use an initial ramdisk:
4252
4253	-> tools/mkimage -n 'Simple Ramdisk Image' \
4254	> -A ppc -O linux -T ramdisk -C gzip \
4255	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4256	Image Name:   Simple Ramdisk Image
4257	Created:      Wed Jan 12 14:01:50 2000
4258	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4259	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4260	Load Address: 0x00000000
4261	Entry Point:  0x00000000
4262
4263
4264Installing a Linux Image:
4265-------------------------
4266
4267To downloading a U-Boot image over the serial (console) interface,
4268you must convert the image to S-Record format:
4269
4270	objcopy -I binary -O srec examples/image examples/image.srec
4271
4272The 'objcopy' does not understand the information in the U-Boot
4273image header, so the resulting S-Record file will be relative to
4274address 0x00000000. To load it to a given address, you need to
4275specify the target address as 'offset' parameter with the 'loads'
4276command.
4277
4278Example: install the image to address 0x40100000 (which on the
4279TQM8xxL is in the first Flash bank):
4280
4281	=> erase 40100000 401FFFFF
4282
4283	.......... done
4284	Erased 8 sectors
4285
4286	=> loads 40100000
4287	## Ready for S-Record download ...
4288	~>examples/image.srec
4289	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4290	...
4291	15989 15990 15991 15992
4292	[file transfer complete]
4293	[connected]
4294	## Start Addr = 0x00000000
4295
4296
4297You can check the success of the download using the 'iminfo' command;
4298this includes a checksum verification so you can be sure no data
4299corruption happened:
4300
4301	=> imi 40100000
4302
4303	## Checking Image at 40100000 ...
4304	   Image Name:	 2.2.13 for initrd on TQM850L
4305	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4306	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4307	   Load Address: 00000000
4308	   Entry Point:	 0000000c
4309	   Verifying Checksum ... OK
4310
4311
4312Boot Linux:
4313-----------
4314
4315The "bootm" command is used to boot an application that is stored in
4316memory (RAM or Flash). In case of a Linux kernel image, the contents
4317of the "bootargs" environment variable is passed to the kernel as
4318parameters. You can check and modify this variable using the
4319"printenv" and "setenv" commands:
4320
4321
4322	=> printenv bootargs
4323	bootargs=root=/dev/ram
4324
4325	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4326
4327	=> printenv bootargs
4328	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4329
4330	=> bootm 40020000
4331	## Booting Linux kernel at 40020000 ...
4332	   Image Name:	 2.2.13 for NFS on TQM850L
4333	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4334	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4335	   Load Address: 00000000
4336	   Entry Point:	 0000000c
4337	   Verifying Checksum ... OK
4338	   Uncompressing Kernel Image ... OK
4339	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
4340	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4341	time_init: decrementer frequency = 187500000/60
4342	Calibrating delay loop... 49.77 BogoMIPS
4343	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4344	...
4345
4346If you want to boot a Linux kernel with initial RAM disk, you pass
4347the memory addresses of both the kernel and the initrd image (PPBCOOT
4348format!) to the "bootm" command:
4349
4350	=> imi 40100000 40200000
4351
4352	## Checking Image at 40100000 ...
4353	   Image Name:	 2.2.13 for initrd on TQM850L
4354	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4355	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4356	   Load Address: 00000000
4357	   Entry Point:	 0000000c
4358	   Verifying Checksum ... OK
4359
4360	## Checking Image at 40200000 ...
4361	   Image Name:	 Simple Ramdisk Image
4362	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4363	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4364	   Load Address: 00000000
4365	   Entry Point:	 00000000
4366	   Verifying Checksum ... OK
4367
4368	=> bootm 40100000 40200000
4369	## Booting Linux kernel at 40100000 ...
4370	   Image Name:	 2.2.13 for initrd on TQM850L
4371	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4372	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4373	   Load Address: 00000000
4374	   Entry Point:	 0000000c
4375	   Verifying Checksum ... OK
4376	   Uncompressing Kernel Image ... OK
4377	## Loading RAMDisk Image at 40200000 ...
4378	   Image Name:	 Simple Ramdisk Image
4379	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4380	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4381	   Load Address: 00000000
4382	   Entry Point:	 00000000
4383	   Verifying Checksum ... OK
4384	   Loading Ramdisk ... OK
4385	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
4386	Boot arguments: root=/dev/ram
4387	time_init: decrementer frequency = 187500000/60
4388	Calibrating delay loop... 49.77 BogoMIPS
4389	...
4390	RAMDISK: Compressed image found at block 0
4391	VFS: Mounted root (ext2 filesystem).
4392
4393	bash#
4394
4395Boot Linux and pass a flat device tree:
4396-----------
4397
4398First, U-Boot must be compiled with the appropriate defines. See the section
4399titled "Linux Kernel Interface" above for a more in depth explanation. The
4400following is an example of how to start a kernel and pass an updated
4401flat device tree:
4402
4403=> print oftaddr
4404oftaddr=0x300000
4405=> print oft
4406oft=oftrees/mpc8540ads.dtb
4407=> tftp $oftaddr $oft
4408Speed: 1000, full duplex
4409Using TSEC0 device
4410TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4411Filename 'oftrees/mpc8540ads.dtb'.
4412Load address: 0x300000
4413Loading: #
4414done
4415Bytes transferred = 4106 (100a hex)
4416=> tftp $loadaddr $bootfile
4417Speed: 1000, full duplex
4418Using TSEC0 device
4419TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4420Filename 'uImage'.
4421Load address: 0x200000
4422Loading:############
4423done
4424Bytes transferred = 1029407 (fb51f hex)
4425=> print loadaddr
4426loadaddr=200000
4427=> print oftaddr
4428oftaddr=0x300000
4429=> bootm $loadaddr - $oftaddr
4430## Booting image at 00200000 ...
4431   Image Name:	 Linux-2.6.17-dirty
4432   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4433   Data Size:	 1029343 Bytes = 1005.2 kB
4434   Load Address: 00000000
4435   Entry Point:	 00000000
4436   Verifying Checksum ... OK
4437   Uncompressing Kernel Image ... OK
4438Booting using flat device tree at 0x300000
4439Using MPC85xx ADS machine description
4440Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4441[snip]
4442
4443
4444More About U-Boot Image Types:
4445------------------------------
4446
4447U-Boot supports the following image types:
4448
4449   "Standalone Programs" are directly runnable in the environment
4450	provided by U-Boot; it is expected that (if they behave
4451	well) you can continue to work in U-Boot after return from
4452	the Standalone Program.
4453   "OS Kernel Images" are usually images of some Embedded OS which
4454	will take over control completely. Usually these programs
4455	will install their own set of exception handlers, device
4456	drivers, set up the MMU, etc. - this means, that you cannot
4457	expect to re-enter U-Boot except by resetting the CPU.
4458   "RAMDisk Images" are more or less just data blocks, and their
4459	parameters (address, size) are passed to an OS kernel that is
4460	being started.
4461   "Multi-File Images" contain several images, typically an OS
4462	(Linux) kernel image and one or more data images like
4463	RAMDisks. This construct is useful for instance when you want
4464	to boot over the network using BOOTP etc., where the boot
4465	server provides just a single image file, but you want to get
4466	for instance an OS kernel and a RAMDisk image.
4467
4468	"Multi-File Images" start with a list of image sizes, each
4469	image size (in bytes) specified by an "uint32_t" in network
4470	byte order. This list is terminated by an "(uint32_t)0".
4471	Immediately after the terminating 0 follow the images, one by
4472	one, all aligned on "uint32_t" boundaries (size rounded up to
4473	a multiple of 4 bytes).
4474
4475   "Firmware Images" are binary images containing firmware (like
4476	U-Boot or FPGA images) which usually will be programmed to
4477	flash memory.
4478
4479   "Script files" are command sequences that will be executed by
4480	U-Boot's command interpreter; this feature is especially
4481	useful when you configure U-Boot to use a real shell (hush)
4482	as command interpreter.
4483
4484Booting the Linux zImage:
4485-------------------------
4486
4487On some platforms, it's possible to boot Linux zImage. This is done
4488using the "bootz" command. The syntax of "bootz" command is the same
4489as the syntax of "bootm" command.
4490
4491Note, defining the CONFIG_SUPPORT_INITRD_RAW allows user to supply
4492kernel with raw initrd images. The syntax is slightly different, the
4493address of the initrd must be augmented by it's size, in the following
4494format: "<initrd addres>:<initrd size>".
4495
4496
4497Standalone HOWTO:
4498=================
4499
4500One of the features of U-Boot is that you can dynamically load and
4501run "standalone" applications, which can use some resources of
4502U-Boot like console I/O functions or interrupt services.
4503
4504Two simple examples are included with the sources:
4505
4506"Hello World" Demo:
4507-------------------
4508
4509'examples/hello_world.c' contains a small "Hello World" Demo
4510application; it is automatically compiled when you build U-Boot.
4511It's configured to run at address 0x00040004, so you can play with it
4512like that:
4513
4514	=> loads
4515	## Ready for S-Record download ...
4516	~>examples/hello_world.srec
4517	1 2 3 4 5 6 7 8 9 10 11 ...
4518	[file transfer complete]
4519	[connected]
4520	## Start Addr = 0x00040004
4521
4522	=> go 40004 Hello World! This is a test.
4523	## Starting application at 0x00040004 ...
4524	Hello World
4525	argc = 7
4526	argv[0] = "40004"
4527	argv[1] = "Hello"
4528	argv[2] = "World!"
4529	argv[3] = "This"
4530	argv[4] = "is"
4531	argv[5] = "a"
4532	argv[6] = "test."
4533	argv[7] = "<NULL>"
4534	Hit any key to exit ...
4535
4536	## Application terminated, rc = 0x0
4537
4538Another example, which demonstrates how to register a CPM interrupt
4539handler with the U-Boot code, can be found in 'examples/timer.c'.
4540Here, a CPM timer is set up to generate an interrupt every second.
4541The interrupt service routine is trivial, just printing a '.'
4542character, but this is just a demo program. The application can be
4543controlled by the following keys:
4544
4545	? - print current values og the CPM Timer registers
4546	b - enable interrupts and start timer
4547	e - stop timer and disable interrupts
4548	q - quit application
4549
4550	=> loads
4551	## Ready for S-Record download ...
4552	~>examples/timer.srec
4553	1 2 3 4 5 6 7 8 9 10 11 ...
4554	[file transfer complete]
4555	[connected]
4556	## Start Addr = 0x00040004
4557
4558	=> go 40004
4559	## Starting application at 0x00040004 ...
4560	TIMERS=0xfff00980
4561	Using timer 1
4562	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4563
4564Hit 'b':
4565	[q, b, e, ?] Set interval 1000000 us
4566	Enabling timer
4567Hit '?':
4568	[q, b, e, ?] ........
4569	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4570Hit '?':
4571	[q, b, e, ?] .
4572	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4573Hit '?':
4574	[q, b, e, ?] .
4575	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4576Hit '?':
4577	[q, b, e, ?] .
4578	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4579Hit 'e':
4580	[q, b, e, ?] ...Stopping timer
4581Hit 'q':
4582	[q, b, e, ?] ## Application terminated, rc = 0x0
4583
4584
4585Minicom warning:
4586================
4587
4588Over time, many people have reported problems when trying to use the
4589"minicom" terminal emulation program for serial download. I (wd)
4590consider minicom to be broken, and recommend not to use it. Under
4591Unix, I recommend to use C-Kermit for general purpose use (and
4592especially for kermit binary protocol download ("loadb" command), and
4593use "cu" for S-Record download ("loads" command).
4594
4595Nevertheless, if you absolutely want to use it try adding this
4596configuration to your "File transfer protocols" section:
4597
4598	   Name	   Program			Name U/D FullScr IO-Red. Multi
4599	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4600	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4601
4602
4603NetBSD Notes:
4604=============
4605
4606Starting at version 0.9.2, U-Boot supports NetBSD both as host
4607(build U-Boot) and target system (boots NetBSD/mpc8xx).
4608
4609Building requires a cross environment; it is known to work on
4610NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4611need gmake since the Makefiles are not compatible with BSD make).
4612Note that the cross-powerpc package does not install include files;
4613attempting to build U-Boot will fail because <machine/ansi.h> is
4614missing.  This file has to be installed and patched manually:
4615
4616	# cd /usr/pkg/cross/powerpc-netbsd/include
4617	# mkdir powerpc
4618	# ln -s powerpc machine
4619	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4620	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4621
4622Native builds *don't* work due to incompatibilities between native
4623and U-Boot include files.
4624
4625Booting assumes that (the first part of) the image booted is a
4626stage-2 loader which in turn loads and then invokes the kernel
4627proper. Loader sources will eventually appear in the NetBSD source
4628tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4629meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4630
4631
4632Implementation Internals:
4633=========================
4634
4635The following is not intended to be a complete description of every
4636implementation detail. However, it should help to understand the
4637inner workings of U-Boot and make it easier to port it to custom
4638hardware.
4639
4640
4641Initial Stack, Global Data:
4642---------------------------
4643
4644The implementation of U-Boot is complicated by the fact that U-Boot
4645starts running out of ROM (flash memory), usually without access to
4646system RAM (because the memory controller is not initialized yet).
4647This means that we don't have writable Data or BSS segments, and BSS
4648is not initialized as zero. To be able to get a C environment working
4649at all, we have to allocate at least a minimal stack. Implementation
4650options for this are defined and restricted by the CPU used: Some CPU
4651models provide on-chip memory (like the IMMR area on MPC8xx and
4652MPC826x processors), on others (parts of) the data cache can be
4653locked as (mis-) used as memory, etc.
4654
4655	Chris Hallinan posted a good summary of these issues to the
4656	U-Boot mailing list:
4657
4658	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4659	From: "Chris Hallinan" <clh@net1plus.com>
4660	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4661	...
4662
4663	Correct me if I'm wrong, folks, but the way I understand it
4664	is this: Using DCACHE as initial RAM for Stack, etc, does not
4665	require any physical RAM backing up the cache. The cleverness
4666	is that the cache is being used as a temporary supply of
4667	necessary storage before the SDRAM controller is setup. It's
4668	beyond the scope of this list to explain the details, but you
4669	can see how this works by studying the cache architecture and
4670	operation in the architecture and processor-specific manuals.
4671
4672	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4673	is another option for the system designer to use as an
4674	initial stack/RAM area prior to SDRAM being available. Either
4675	option should work for you. Using CS 4 should be fine if your
4676	board designers haven't used it for something that would
4677	cause you grief during the initial boot! It is frequently not
4678	used.
4679
4680	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4681	with your processor/board/system design. The default value
4682	you will find in any recent u-boot distribution in
4683	walnut.h should work for you. I'd set it to a value larger
4684	than your SDRAM module. If you have a 64MB SDRAM module, set
4685	it above 400_0000. Just make sure your board has no resources
4686	that are supposed to respond to that address! That code in
4687	start.S has been around a while and should work as is when
4688	you get the config right.
4689
4690	-Chris Hallinan
4691	DS4.COM, Inc.
4692
4693It is essential to remember this, since it has some impact on the C
4694code for the initialization procedures:
4695
4696* Initialized global data (data segment) is read-only. Do not attempt
4697  to write it.
4698
4699* Do not use any uninitialized global data (or implicitely initialized
4700  as zero data - BSS segment) at all - this is undefined, initiali-
4701  zation is performed later (when relocating to RAM).
4702
4703* Stack space is very limited. Avoid big data buffers or things like
4704  that.
4705
4706Having only the stack as writable memory limits means we cannot use
4707normal global data to share information beween the code. But it
4708turned out that the implementation of U-Boot can be greatly
4709simplified by making a global data structure (gd_t) available to all
4710functions. We could pass a pointer to this data as argument to _all_
4711functions, but this would bloat the code. Instead we use a feature of
4712the GCC compiler (Global Register Variables) to share the data: we
4713place a pointer (gd) to the global data into a register which we
4714reserve for this purpose.
4715
4716When choosing a register for such a purpose we are restricted by the
4717relevant  (E)ABI  specifications for the current architecture, and by
4718GCC's implementation.
4719
4720For PowerPC, the following registers have specific use:
4721	R1:	stack pointer
4722	R2:	reserved for system use
4723	R3-R4:	parameter passing and return values
4724	R5-R10: parameter passing
4725	R13:	small data area pointer
4726	R30:	GOT pointer
4727	R31:	frame pointer
4728
4729	(U-Boot also uses R12 as internal GOT pointer. r12
4730	is a volatile register so r12 needs to be reset when
4731	going back and forth between asm and C)
4732
4733    ==> U-Boot will use R2 to hold a pointer to the global data
4734
4735    Note: on PPC, we could use a static initializer (since the
4736    address of the global data structure is known at compile time),
4737    but it turned out that reserving a register results in somewhat
4738    smaller code - although the code savings are not that big (on
4739    average for all boards 752 bytes for the whole U-Boot image,
4740    624 text + 127 data).
4741
4742On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4743	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4744
4745    ==> U-Boot will use P3 to hold a pointer to the global data
4746
4747On ARM, the following registers are used:
4748
4749	R0:	function argument word/integer result
4750	R1-R3:	function argument word
4751	R9:	GOT pointer
4752	R10:	stack limit (used only if stack checking if enabled)
4753	R11:	argument (frame) pointer
4754	R12:	temporary workspace
4755	R13:	stack pointer
4756	R14:	link register
4757	R15:	program counter
4758
4759    ==> U-Boot will use R8 to hold a pointer to the global data
4760
4761On Nios II, the ABI is documented here:
4762	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4763
4764    ==> U-Boot will use gp to hold a pointer to the global data
4765
4766    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4767    to access small data sections, so gp is free.
4768
4769On NDS32, the following registers are used:
4770
4771	R0-R1:	argument/return
4772	R2-R5:	argument
4773	R15:	temporary register for assembler
4774	R16:	trampoline register
4775	R28:	frame pointer (FP)
4776	R29:	global pointer (GP)
4777	R30:	link register (LP)
4778	R31:	stack pointer (SP)
4779	PC:	program counter (PC)
4780
4781    ==> U-Boot will use R10 to hold a pointer to the global data
4782
4783NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4784or current versions of GCC may "optimize" the code too much.
4785
4786Memory Management:
4787------------------
4788
4789U-Boot runs in system state and uses physical addresses, i.e. the
4790MMU is not used either for address mapping nor for memory protection.
4791
4792The available memory is mapped to fixed addresses using the memory
4793controller. In this process, a contiguous block is formed for each
4794memory type (Flash, SDRAM, SRAM), even when it consists of several
4795physical memory banks.
4796
4797U-Boot is installed in the first 128 kB of the first Flash bank (on
4798TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4799booting and sizing and initializing DRAM, the code relocates itself
4800to the upper end of DRAM. Immediately below the U-Boot code some
4801memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4802configuration setting]. Below that, a structure with global Board
4803Info data is placed, followed by the stack (growing downward).
4804
4805Additionally, some exception handler code is copied to the low 8 kB
4806of DRAM (0x00000000 ... 0x00001FFF).
4807
4808So a typical memory configuration with 16 MB of DRAM could look like
4809this:
4810
4811	0x0000 0000	Exception Vector code
4812	      :
4813	0x0000 1FFF
4814	0x0000 2000	Free for Application Use
4815	      :
4816	      :
4817
4818	      :
4819	      :
4820	0x00FB FF20	Monitor Stack (Growing downward)
4821	0x00FB FFAC	Board Info Data and permanent copy of global data
4822	0x00FC 0000	Malloc Arena
4823	      :
4824	0x00FD FFFF
4825	0x00FE 0000	RAM Copy of Monitor Code
4826	...		eventually: LCD or video framebuffer
4827	...		eventually: pRAM (Protected RAM - unchanged by reset)
4828	0x00FF FFFF	[End of RAM]
4829
4830
4831System Initialization:
4832----------------------
4833
4834In the reset configuration, U-Boot starts at the reset entry point
4835(on most PowerPC systems at address 0x00000100). Because of the reset
4836configuration for CS0# this is a mirror of the onboard Flash memory.
4837To be able to re-map memory U-Boot then jumps to its link address.
4838To be able to implement the initialization code in C, a (small!)
4839initial stack is set up in the internal Dual Ported RAM (in case CPUs
4840which provide such a feature like MPC8xx or MPC8260), or in a locked
4841part of the data cache. After that, U-Boot initializes the CPU core,
4842the caches and the SIU.
4843
4844Next, all (potentially) available memory banks are mapped using a
4845preliminary mapping. For example, we put them on 512 MB boundaries
4846(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4847on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4848programmed for SDRAM access. Using the temporary configuration, a
4849simple memory test is run that determines the size of the SDRAM
4850banks.
4851
4852When there is more than one SDRAM bank, and the banks are of
4853different size, the largest is mapped first. For equal size, the first
4854bank (CS2#) is mapped first. The first mapping is always for address
48550x00000000, with any additional banks following immediately to create
4856contiguous memory starting from 0.
4857
4858Then, the monitor installs itself at the upper end of the SDRAM area
4859and allocates memory for use by malloc() and for the global Board
4860Info data; also, the exception vector code is copied to the low RAM
4861pages, and the final stack is set up.
4862
4863Only after this relocation will you have a "normal" C environment;
4864until that you are restricted in several ways, mostly because you are
4865running from ROM, and because the code will have to be relocated to a
4866new address in RAM.
4867
4868
4869U-Boot Porting Guide:
4870----------------------
4871
4872[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4873list, October 2002]
4874
4875
4876int main(int argc, char *argv[])
4877{
4878	sighandler_t no_more_time;
4879
4880	signal(SIGALRM, no_more_time);
4881	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4882
4883	if (available_money > available_manpower) {
4884		Pay consultant to port U-Boot;
4885		return 0;
4886	}
4887
4888	Download latest U-Boot source;
4889
4890	Subscribe to u-boot mailing list;
4891
4892	if (clueless)
4893		email("Hi, I am new to U-Boot, how do I get started?");
4894
4895	while (learning) {
4896		Read the README file in the top level directory;
4897		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4898		Read applicable doc/*.README;
4899		Read the source, Luke;
4900		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4901	}
4902
4903	if (available_money > toLocalCurrency ($2500))
4904		Buy a BDI3000;
4905	else
4906		Add a lot of aggravation and time;
4907
4908	if (a similar board exists) {	/* hopefully... */
4909		cp -a board/<similar> board/<myboard>
4910		cp include/configs/<similar>.h include/configs/<myboard>.h
4911	} else {
4912		Create your own board support subdirectory;
4913		Create your own board include/configs/<myboard>.h file;
4914	}
4915	Edit new board/<myboard> files
4916	Edit new include/configs/<myboard>.h
4917
4918	while (!accepted) {
4919		while (!running) {
4920			do {
4921				Add / modify source code;
4922			} until (compiles);
4923			Debug;
4924			if (clueless)
4925				email("Hi, I am having problems...");
4926		}
4927		Send patch file to the U-Boot email list;
4928		if (reasonable critiques)
4929			Incorporate improvements from email list code review;
4930		else
4931			Defend code as written;
4932	}
4933
4934	return 0;
4935}
4936
4937void no_more_time (int sig)
4938{
4939      hire_a_guru();
4940}
4941
4942
4943Coding Standards:
4944-----------------
4945
4946All contributions to U-Boot should conform to the Linux kernel
4947coding style; see the file "Documentation/CodingStyle" and the script
4948"scripts/Lindent" in your Linux kernel source directory.
4949
4950Source files originating from a different project (for example the
4951MTD subsystem) are generally exempt from these guidelines and are not
4952reformated to ease subsequent migration to newer versions of those
4953sources.
4954
4955Please note that U-Boot is implemented in C (and to some small parts in
4956Assembler); no C++ is used, so please do not use C++ style comments (//)
4957in your code.
4958
4959Please also stick to the following formatting rules:
4960- remove any trailing white space
4961- use TAB characters for indentation and vertical alignment, not spaces
4962- make sure NOT to use DOS '\r\n' line feeds
4963- do not add more than 2 consecutive empty lines to source files
4964- do not add trailing empty lines to source files
4965
4966Submissions which do not conform to the standards may be returned
4967with a request to reformat the changes.
4968
4969
4970Submitting Patches:
4971-------------------
4972
4973Since the number of patches for U-Boot is growing, we need to
4974establish some rules. Submissions which do not conform to these rules
4975may be rejected, even when they contain important and valuable stuff.
4976
4977Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4978
4979Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4980see http://lists.denx.de/mailman/listinfo/u-boot
4981
4982When you send a patch, please include the following information with
4983it:
4984
4985* For bug fixes: a description of the bug and how your patch fixes
4986  this bug. Please try to include a way of demonstrating that the
4987  patch actually fixes something.
4988
4989* For new features: a description of the feature and your
4990  implementation.
4991
4992* A CHANGELOG entry as plaintext (separate from the patch)
4993
4994* For major contributions, your entry to the CREDITS file
4995
4996* When you add support for a new board, don't forget to add this
4997  board to the MAINTAINERS file, too.
4998
4999* If your patch adds new configuration options, don't forget to
5000  document these in the README file.
5001
5002* The patch itself. If you are using git (which is *strongly*
5003  recommended) you can easily generate the patch using the
5004  "git format-patch". If you then use "git send-email" to send it to
5005  the U-Boot mailing list, you will avoid most of the common problems
5006  with some other mail clients.
5007
5008  If you cannot use git, use "diff -purN OLD NEW". If your version of
5009  diff does not support these options, then get the latest version of
5010  GNU diff.
5011
5012  The current directory when running this command shall be the parent
5013  directory of the U-Boot source tree (i. e. please make sure that
5014  your patch includes sufficient directory information for the
5015  affected files).
5016
5017  We prefer patches as plain text. MIME attachments are discouraged,
5018  and compressed attachments must not be used.
5019
5020* If one logical set of modifications affects or creates several
5021  files, all these changes shall be submitted in a SINGLE patch file.
5022
5023* Changesets that contain different, unrelated modifications shall be
5024  submitted as SEPARATE patches, one patch per changeset.
5025
5026
5027Notes:
5028
5029* Before sending the patch, run the MAKEALL script on your patched
5030  source tree and make sure that no errors or warnings are reported
5031  for any of the boards.
5032
5033* Keep your modifications to the necessary minimum: A patch
5034  containing several unrelated changes or arbitrary reformats will be
5035  returned with a request to re-formatting / split it.
5036
5037* If you modify existing code, make sure that your new code does not
5038  add to the memory footprint of the code ;-) Small is beautiful!
5039  When adding new features, these should compile conditionally only
5040  (using #ifdef), and the resulting code with the new feature
5041  disabled must not need more memory than the old code without your
5042  modification.
5043
5044* Remember that there is a size limit of 100 kB per message on the
5045  u-boot mailing list. Bigger patches will be moderated. If they are
5046  reasonable and not too big, they will be acknowledged. But patches
5047  bigger than the size limit should be avoided.
5048