xref: /rk3399_rockchip-uboot/README (revision f9da0f894328802cb8aaeb8a24660e37ff624d26)
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- Intel Monahans options:
378		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
379
380		Defines the Monahans run mode to oscillator
381		ratio. Valid values are 8, 16, 24, 31. The core
382		frequency is this value multiplied by 13 MHz.
383
384		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
385
386		Defines the Monahans turbo mode to oscillator
387		ratio. Valid values are 1 (default if undefined) and
388		2. The core frequency as calculated above is multiplied
389		by this value.
390
391- MIPS CPU options:
392		CONFIG_SYS_INIT_SP_OFFSET
393
394		Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
395		pointer. This is needed for the temporary stack before
396		relocation.
397
398		CONFIG_SYS_MIPS_CACHE_MODE
399
400		Cache operation mode for the MIPS CPU.
401		See also arch/mips/include/asm/mipsregs.h.
402		Possible values are:
403			CONF_CM_CACHABLE_NO_WA
404			CONF_CM_CACHABLE_WA
405			CONF_CM_UNCACHED
406			CONF_CM_CACHABLE_NONCOHERENT
407			CONF_CM_CACHABLE_CE
408			CONF_CM_CACHABLE_COW
409			CONF_CM_CACHABLE_CUW
410			CONF_CM_CACHABLE_ACCELERATED
411
412		CONFIG_SYS_XWAY_EBU_BOOTCFG
413
414		Special option for Lantiq XWAY SoCs for booting from NOR flash.
415		See also arch/mips/cpu/mips32/start.S.
416
417		CONFIG_XWAY_SWAP_BYTES
418
419		Enable compilation of tools/xway-swap-bytes needed for Lantiq
420		XWAY SoCs for booting from NOR flash. The U-Boot image needs to
421		be swapped if a flash programmer is used.
422
423- ARM options:
424		CONFIG_SYS_EXCEPTION_VECTORS_HIGH
425
426		Select high exception vectors of the ARM core, e.g., do not
427		clear the V bit of the c1 register of CP15.
428
429- Linux Kernel Interface:
430		CONFIG_CLOCKS_IN_MHZ
431
432		U-Boot stores all clock information in Hz
433		internally. For binary compatibility with older Linux
434		kernels (which expect the clocks passed in the
435		bd_info data to be in MHz) the environment variable
436		"clocks_in_mhz" can be defined so that U-Boot
437		converts clock data to MHZ before passing it to the
438		Linux kernel.
439		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
440		"clocks_in_mhz=1" is automatically included in the
441		default environment.
442
443		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
444
445		When transferring memsize parameter to linux, some versions
446		expect it to be in bytes, others in MB.
447		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
448
449		CONFIG_OF_LIBFDT
450
451		New kernel versions are expecting firmware settings to be
452		passed using flattened device trees (based on open firmware
453		concepts).
454
455		CONFIG_OF_LIBFDT
456		 * New libfdt-based support
457		 * Adds the "fdt" command
458		 * The bootm command automatically updates the fdt
459
460		OF_CPU - The proper name of the cpus node (only required for
461			MPC512X and MPC5xxx based boards).
462		OF_SOC - The proper name of the soc node (only required for
463			MPC512X and MPC5xxx based boards).
464		OF_TBCLK - The timebase frequency.
465		OF_STDOUT_PATH - The path to the console device
466
467		boards with QUICC Engines require OF_QE to set UCC MAC
468		addresses
469
470		CONFIG_OF_BOARD_SETUP
471
472		Board code has addition modification that it wants to make
473		to the flat device tree before handing it off to the kernel
474
475		CONFIG_OF_BOOT_CPU
476
477		This define fills in the correct boot CPU in the boot
478		param header, the default value is zero if undefined.
479
480		CONFIG_OF_IDE_FIXUP
481
482		U-Boot can detect if an IDE device is present or not.
483		If not, and this new config option is activated, U-Boot
484		removes the ATA node from the DTS before booting Linux,
485		so the Linux IDE driver does not probe the device and
486		crash. This is needed for buggy hardware (uc101) where
487		no pull down resistor is connected to the signal IDE5V_DD7.
488
489		CONFIG_MACH_TYPE	[relevant for ARM only][mandatory]
490
491		This setting is mandatory for all boards that have only one
492		machine type and must be used to specify the machine type
493		number as it appears in the ARM machine registry
494		(see http://www.arm.linux.org.uk/developer/machines/).
495		Only boards that have multiple machine types supported
496		in a single configuration file and the machine type is
497		runtime discoverable, do not have to use this setting.
498
499- vxWorks boot parameters:
500
501		bootvx constructs a valid bootline using the following
502		environments variables: bootfile, ipaddr, serverip, hostname.
503		It loads the vxWorks image pointed bootfile.
504
505		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
506		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
507		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
508		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
509
510		CONFIG_SYS_VXWORKS_ADD_PARAMS
511
512		Add it at the end of the bootline. E.g "u=username pw=secret"
513
514		Note: If a "bootargs" environment is defined, it will overwride
515		the defaults discussed just above.
516
517- Cache Configuration:
518		CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot
519		CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot
520		CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
521
522- Cache Configuration for ARM:
523		CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
524				      controller
525		CONFIG_SYS_PL310_BASE - Physical base address of PL310
526					controller register space
527
528- Serial Ports:
529		CONFIG_PL010_SERIAL
530
531		Define this if you want support for Amba PrimeCell PL010 UARTs.
532
533		CONFIG_PL011_SERIAL
534
535		Define this if you want support for Amba PrimeCell PL011 UARTs.
536
537		CONFIG_PL011_CLOCK
538
539		If you have Amba PrimeCell PL011 UARTs, set this variable to
540		the clock speed of the UARTs.
541
542		CONFIG_PL01x_PORTS
543
544		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
545		define this to a list of base addresses for each (supported)
546		port. See e.g. include/configs/versatile.h
547
548		CONFIG_PL011_SERIAL_RLCR
549
550		Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)
551		have separate receive and transmit line control registers.  Set
552		this variable to initialize the extra register.
553
554		CONFIG_PL011_SERIAL_FLUSH_ON_INIT
555
556		On some platforms (e.g. U8500) U-Boot is loaded by a second stage
557		boot loader that has already initialized the UART.  Define this
558		variable to flush the UART at init time.
559
560
561- Console Interface:
562		Depending on board, define exactly one serial port
563		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
564		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
565		console by defining CONFIG_8xx_CONS_NONE
566
567		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
568		port routines must be defined elsewhere
569		(i.e. serial_init(), serial_getc(), ...)
570
571		CONFIG_CFB_CONSOLE
572		Enables console device for a color framebuffer. Needs following
573		defines (cf. smiLynxEM, i8042)
574			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
575						(default big endian)
576			VIDEO_HW_RECTFILL	graphic chip supports
577						rectangle fill
578						(cf. smiLynxEM)
579			VIDEO_HW_BITBLT		graphic chip supports
580						bit-blit (cf. smiLynxEM)
581			VIDEO_VISIBLE_COLS	visible pixel columns
582						(cols=pitch)
583			VIDEO_VISIBLE_ROWS	visible pixel rows
584			VIDEO_PIXEL_SIZE	bytes per pixel
585			VIDEO_DATA_FORMAT	graphic data format
586						(0-5, cf. cfb_console.c)
587			VIDEO_FB_ADRS		framebuffer address
588			VIDEO_KBD_INIT_FCT	keyboard int fct
589						(i.e. i8042_kbd_init())
590			VIDEO_TSTC_FCT		test char fct
591						(i.e. i8042_tstc)
592			VIDEO_GETC_FCT		get char fct
593						(i.e. i8042_getc)
594			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
595						(requires blink timer
596						cf. i8042.c)
597			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
598			CONFIG_CONSOLE_TIME	display time/date info in
599						upper right corner
600						(requires CONFIG_CMD_DATE)
601			CONFIG_VIDEO_LOGO	display Linux logo in
602						upper left corner
603			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
604						linux_logo.h for logo.
605						Requires CONFIG_VIDEO_LOGO
606			CONFIG_CONSOLE_EXTRA_INFO
607						additional board info beside
608						the logo
609
610		When CONFIG_CFB_CONSOLE is defined, video console is
611		default i/o. Serial console can be forced with
612		environment 'console=serial'.
613
614		When CONFIG_SILENT_CONSOLE is defined, all console
615		messages (by U-Boot and Linux!) can be silenced with
616		the "silent" environment variable. See
617		doc/README.silent for more information.
618
619- Console Baudrate:
620		CONFIG_BAUDRATE - in bps
621		Select one of the baudrates listed in
622		CONFIG_SYS_BAUDRATE_TABLE, see below.
623		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
624
625- Console Rx buffer length
626		With CONFIG_SYS_SMC_RXBUFLEN it is possible to define
627		the maximum receive buffer length for the SMC.
628		This option is actual only for 82xx and 8xx possible.
629		If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE
630		must be defined, to setup the maximum idle timeout for
631		the SMC.
632
633- Pre-Console Buffer:
634		Prior to the console being initialised (i.e. serial UART
635		initialised etc) all console output is silently discarded.
636		Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to
637		buffer any console messages prior to the console being
638		initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ
639		bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is
640		a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ
641		bytes are output before the console is initialised, the
642		earlier bytes are discarded.
643
644		'Sane' compilers will generate smaller code if
645		CONFIG_PRE_CON_BUF_SZ is a power of 2
646
647- Safe printf() functions
648		Define CONFIG_SYS_VSNPRINTF to compile in safe versions of
649		the printf() functions. These are defined in
650		include/vsprintf.h and include snprintf(), vsnprintf() and
651		so on. Code size increase is approximately 300-500 bytes.
652		If this option is not given then these functions will
653		silently discard their buffer size argument - this means
654		you are not getting any overflow checking in this case.
655
656- Boot Delay:	CONFIG_BOOTDELAY - in seconds
657		Delay before automatically booting the default image;
658		set to -1 to disable autoboot.
659
660		See doc/README.autoboot for these options that
661		work with CONFIG_BOOTDELAY. None are required.
662		CONFIG_BOOT_RETRY_TIME
663		CONFIG_BOOT_RETRY_MIN
664		CONFIG_AUTOBOOT_KEYED
665		CONFIG_AUTOBOOT_PROMPT
666		CONFIG_AUTOBOOT_DELAY_STR
667		CONFIG_AUTOBOOT_STOP_STR
668		CONFIG_AUTOBOOT_DELAY_STR2
669		CONFIG_AUTOBOOT_STOP_STR2
670		CONFIG_ZERO_BOOTDELAY_CHECK
671		CONFIG_RESET_TO_RETRY
672
673- Autoboot Command:
674		CONFIG_BOOTCOMMAND
675		Only needed when CONFIG_BOOTDELAY is enabled;
676		define a command string that is automatically executed
677		when no character is read on the console interface
678		within "Boot Delay" after reset.
679
680		CONFIG_BOOTARGS
681		This can be used to pass arguments to the bootm
682		command. The value of CONFIG_BOOTARGS goes into the
683		environment value "bootargs".
684
685		CONFIG_RAMBOOT and CONFIG_NFSBOOT
686		The value of these goes into the environment as
687		"ramboot" and "nfsboot" respectively, and can be used
688		as a convenience, when switching between booting from
689		RAM and NFS.
690
691- Pre-Boot Commands:
692		CONFIG_PREBOOT
693
694		When this option is #defined, the existence of the
695		environment variable "preboot" will be checked
696		immediately before starting the CONFIG_BOOTDELAY
697		countdown and/or running the auto-boot command resp.
698		entering interactive mode.
699
700		This feature is especially useful when "preboot" is
701		automatically generated or modified. For an example
702		see the LWMON board specific code: here "preboot" is
703		modified when the user holds down a certain
704		combination of keys on the (special) keyboard when
705		booting the systems
706
707- Serial Download Echo Mode:
708		CONFIG_LOADS_ECHO
709		If defined to 1, all characters received during a
710		serial download (using the "loads" command) are
711		echoed back. This might be needed by some terminal
712		emulations (like "cu"), but may as well just take
713		time on others. This setting #define's the initial
714		value of the "loads_echo" environment variable.
715
716- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
717		CONFIG_KGDB_BAUDRATE
718		Select one of the baudrates listed in
719		CONFIG_SYS_BAUDRATE_TABLE, see below.
720
721- Monitor Functions:
722		Monitor commands can be included or excluded
723		from the build by using the #include files
724		"config_cmd_all.h" and #undef'ing unwanted
725		commands, or using "config_cmd_default.h"
726		and augmenting with additional #define's
727		for wanted commands.
728
729		The default command configuration includes all commands
730		except those marked below with a "*".
731
732		CONFIG_CMD_ASKENV	* ask for env variable
733		CONFIG_CMD_BDI		  bdinfo
734		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
735		CONFIG_CMD_BMP		* BMP support
736		CONFIG_CMD_BSP		* Board specific commands
737		CONFIG_CMD_BOOTD	  bootd
738		CONFIG_CMD_CACHE	* icache, dcache
739		CONFIG_CMD_CONSOLE	  coninfo
740		CONFIG_CMD_CRC32	* crc32
741		CONFIG_CMD_DATE		* support for RTC, date/time...
742		CONFIG_CMD_DHCP		* DHCP support
743		CONFIG_CMD_DIAG		* Diagnostics
744		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
745		CONFIG_CMD_DS4510_INFO	* ds4510 I2C info command
746		CONFIG_CMD_DS4510_MEM	* ds4510 I2C eeprom/sram commansd
747		CONFIG_CMD_DS4510_RST	* ds4510 I2C rst command
748		CONFIG_CMD_DTT		* Digital Therm and Thermostat
749		CONFIG_CMD_ECHO		  echo arguments
750		CONFIG_CMD_EDITENV	  edit env variable
751		CONFIG_CMD_EEPROM	* EEPROM read/write support
752		CONFIG_CMD_ELF		* bootelf, bootvx
753		CONFIG_CMD_EXPORTENV	* export the environment
754		CONFIG_CMD_SAVEENV	  saveenv
755		CONFIG_CMD_FDC		* Floppy Disk Support
756		CONFIG_CMD_FAT		* FAT partition support
757		CONFIG_CMD_FDOS		* Dos diskette Support
758		CONFIG_CMD_FLASH	  flinfo, erase, protect
759		CONFIG_CMD_FPGA		  FPGA device initialization support
760		CONFIG_CMD_GO		* the 'go' command (exec code)
761		CONFIG_CMD_GREPENV	* search environment
762		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
763		CONFIG_CMD_I2C		* I2C serial bus support
764		CONFIG_CMD_IDE		* IDE harddisk support
765		CONFIG_CMD_IMI		  iminfo
766		CONFIG_CMD_IMLS		  List all found images
767		CONFIG_CMD_IMMAP	* IMMR dump support
768		CONFIG_CMD_IMPORTENV	* import an environment
769		CONFIG_CMD_IRQ		* irqinfo
770		CONFIG_CMD_ITEST	  Integer/string test of 2 values
771		CONFIG_CMD_JFFS2	* JFFS2 Support
772		CONFIG_CMD_KGDB		* kgdb
773		CONFIG_CMD_LDRINFO	  ldrinfo (display Blackfin loader)
774		CONFIG_CMD_LOADB	  loadb
775		CONFIG_CMD_LOADS	  loads
776		CONFIG_CMD_MD5SUM	  print md5 message digest
777					  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)
778		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
779					  loop, loopw, mtest
780		CONFIG_CMD_MISC		  Misc functions like sleep etc
781		CONFIG_CMD_MMC		* MMC memory mapped support
782		CONFIG_CMD_MII		* MII utility commands
783		CONFIG_CMD_MTDPARTS	* MTD partition support
784		CONFIG_CMD_NAND		* NAND support
785		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
786		CONFIG_CMD_PCA953X	* PCA953x I2C gpio commands
787		CONFIG_CMD_PCA953X_INFO * PCA953x I2C gpio info command
788		CONFIG_CMD_PCI		* pciinfo
789		CONFIG_CMD_PCMCIA		* PCMCIA support
790		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
791					  host
792		CONFIG_CMD_PORTIO	* Port I/O
793		CONFIG_CMD_REGINFO	* Register dump
794		CONFIG_CMD_RUN		  run command in env variable
795		CONFIG_CMD_SAVES	* save S record dump
796		CONFIG_CMD_SCSI		* SCSI Support
797		CONFIG_CMD_SDRAM	* print SDRAM configuration information
798					  (requires CONFIG_CMD_I2C)
799		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
800					  (4xx only)
801		CONFIG_CMD_SF		* Read/write/erase SPI NOR flash
802		CONFIG_CMD_SHA1SUM	  print sha1 memory digest
803					  (requires CONFIG_CMD_MEMORY)
804		CONFIG_CMD_SOURCE	  "source" command Support
805		CONFIG_CMD_SPI		* SPI serial bus support
806		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
807		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
808		CONFIG_CMD_TIME		* run command and report execution time
809		CONFIG_CMD_USB		* USB support
810		CONFIG_CMD_CDP		* Cisco Discover Protocol support
811		CONFIG_CMD_FSL		* Microblaze FSL support
812
813
814		EXAMPLE: If you want all functions except of network
815		support you can write:
816
817		#include "config_cmd_all.h"
818		#undef CONFIG_CMD_NET
819
820	Other Commands:
821		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
822
823	Note:	Don't enable the "icache" and "dcache" commands
824		(configuration option CONFIG_CMD_CACHE) unless you know
825		what you (and your U-Boot users) are doing. Data
826		cache cannot be enabled on systems like the 8xx or
827		8260 (where accesses to the IMMR region must be
828		uncached), and it cannot be disabled on all other
829		systems where we (mis-) use the data cache to hold an
830		initial stack and some data.
831
832
833		XXX - this list needs to get updated!
834
835- Device tree:
836		CONFIG_OF_CONTROL
837		If this variable is defined, U-Boot will use a device tree
838		to configure its devices, instead of relying on statically
839		compiled #defines in the board file. This option is
840		experimental and only available on a few boards. The device
841		tree is available in the global data as gd->fdt_blob.
842
843		U-Boot needs to get its device tree from somewhere. This can
844		be done using one of the two options below:
845
846		CONFIG_OF_EMBED
847		If this variable is defined, U-Boot will embed a device tree
848		binary in its image. This device tree file should be in the
849		board directory and called <soc>-<board>.dts. The binary file
850		is then picked up in board_init_f() and made available through
851		the global data structure as gd->blob.
852
853		CONFIG_OF_SEPARATE
854		If this variable is defined, U-Boot will build a device tree
855		binary. It will be called u-boot.dtb. Architecture-specific
856		code will locate it at run-time. Generally this works by:
857
858			cat u-boot.bin u-boot.dtb >image.bin
859
860		and in fact, U-Boot does this for you, creating a file called
861		u-boot-dtb.bin which is useful in the common case. You can
862		still use the individual files if you need something more
863		exotic.
864
865- Watchdog:
866		CONFIG_WATCHDOG
867		If this variable is defined, it enables watchdog
868		support for the SoC. There must be support in the SoC
869		specific code for a watchdog. For the 8xx and 8260
870		CPUs, the SIU Watchdog feature is enabled in the SYPCR
871		register.  When supported for a specific SoC is
872		available, then no further board specific code should
873		be needed to use it.
874
875		CONFIG_HW_WATCHDOG
876		When using a watchdog circuitry external to the used
877		SoC, then define this variable and provide board
878		specific code for the "hw_watchdog_reset" function.
879
880- U-Boot Version:
881		CONFIG_VERSION_VARIABLE
882		If this variable is defined, an environment variable
883		named "ver" is created by U-Boot showing the U-Boot
884		version as printed by the "version" command.
885		This variable is readonly.
886
887- Real-Time Clock:
888
889		When CONFIG_CMD_DATE is selected, the type of the RTC
890		has to be selected, too. Define exactly one of the
891		following options:
892
893		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
894		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
895		CONFIG_RTC_MC13XXX	- use MC13783 or MC13892 RTC
896		CONFIG_RTC_MC146818	- use MC146818 RTC
897		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
898		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
899		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
900		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
901		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
902		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
903		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
904		CONFIG_SYS_RV3029_TCR	- enable trickle charger on
905					  RV3029 RTC.
906
907		Note that if the RTC uses I2C, then the I2C interface
908		must also be configured. See I2C Support, below.
909
910- GPIO Support:
911		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
912		CONFIG_PCA953X_INFO	- enable pca953x info command
913
914		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
915		chip-ngpio pairs that tell the PCA953X driver the number of
916		pins supported by a particular chip.
917
918		Note that if the GPIO device uses I2C, then the I2C interface
919		must also be configured. See I2C Support, below.
920
921- Timestamp Support:
922
923		When CONFIG_TIMESTAMP is selected, the timestamp
924		(date and time) of an image is printed by image
925		commands like bootm or iminfo. This option is
926		automatically enabled when you select CONFIG_CMD_DATE .
927
928- Partition Support:
929		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
930		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
931
932		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
933		CONFIG_CMD_SCSI) you must configure support for at
934		least one partition type as well.
935
936- IDE Reset method:
937		CONFIG_IDE_RESET_ROUTINE - this is defined in several
938		board configurations files but used nowhere!
939
940		CONFIG_IDE_RESET - is this is defined, IDE Reset will
941		be performed by calling the function
942			ide_set_reset(int reset)
943		which has to be defined in a board specific file
944
945- ATAPI Support:
946		CONFIG_ATAPI
947
948		Set this to enable ATAPI support.
949
950- LBA48 Support
951		CONFIG_LBA48
952
953		Set this to enable support for disks larger than 137GB
954		Also look at CONFIG_SYS_64BIT_LBA.
955		Whithout these , LBA48 support uses 32bit variables and will 'only'
956		support disks up to 2.1TB.
957
958		CONFIG_SYS_64BIT_LBA:
959			When enabled, makes the IDE subsystem use 64bit sector addresses.
960			Default is 32bit.
961
962- SCSI Support:
963		At the moment only there is only support for the
964		SYM53C8XX SCSI controller; define
965		CONFIG_SCSI_SYM53C8XX to enable it.
966
967		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
968		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
969		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
970		maximum numbers of LUNs, SCSI ID's and target
971		devices.
972		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
973
974- NETWORK Support (PCI):
975		CONFIG_E1000
976		Support for Intel 8254x/8257x gigabit chips.
977
978		CONFIG_E1000_SPI
979		Utility code for direct access to the SPI bus on Intel 8257x.
980		This does not do anything useful unless you set at least one
981		of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
982
983		CONFIG_E1000_SPI_GENERIC
984		Allow generic access to the SPI bus on the Intel 8257x, for
985		example with the "sspi" command.
986
987		CONFIG_CMD_E1000
988		Management command for E1000 devices.  When used on devices
989		with SPI support you can reprogram the EEPROM from U-Boot.
990
991		CONFIG_E1000_FALLBACK_MAC
992		default MAC for empty EEPROM after production.
993
994		CONFIG_EEPRO100
995		Support for Intel 82557/82559/82559ER chips.
996		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
997		write routine for first time initialisation.
998
999		CONFIG_TULIP
1000		Support for Digital 2114x chips.
1001		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
1002		modem chip initialisation (KS8761/QS6611).
1003
1004		CONFIG_NATSEMI
1005		Support for National dp83815 chips.
1006
1007		CONFIG_NS8382X
1008		Support for National dp8382[01] gigabit chips.
1009
1010- NETWORK Support (other):
1011
1012		CONFIG_DRIVER_AT91EMAC
1013		Support for AT91RM9200 EMAC.
1014
1015			CONFIG_RMII
1016			Define this to use reduced MII inteface
1017
1018			CONFIG_DRIVER_AT91EMAC_QUIET
1019			If this defined, the driver is quiet.
1020			The driver doen't show link status messages.
1021
1022		CONFIG_CALXEDA_XGMAC
1023		Support for the Calxeda XGMAC device
1024
1025		CONFIG_DRIVER_LAN91C96
1026		Support for SMSC's LAN91C96 chips.
1027
1028			CONFIG_LAN91C96_BASE
1029			Define this to hold the physical address
1030			of the LAN91C96's I/O space
1031
1032			CONFIG_LAN91C96_USE_32_BIT
1033			Define this to enable 32 bit addressing
1034
1035		CONFIG_DRIVER_SMC91111
1036		Support for SMSC's LAN91C111 chip
1037
1038			CONFIG_SMC91111_BASE
1039			Define this to hold the physical address
1040			of the device (I/O space)
1041
1042			CONFIG_SMC_USE_32_BIT
1043			Define this if data bus is 32 bits
1044
1045			CONFIG_SMC_USE_IOFUNCS
1046			Define this to use i/o functions instead of macros
1047			(some hardware wont work with macros)
1048
1049		CONFIG_DRIVER_TI_EMAC
1050		Support for davinci emac
1051
1052			CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
1053			Define this if you have more then 3 PHYs.
1054
1055		CONFIG_FTGMAC100
1056		Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
1057
1058			CONFIG_FTGMAC100_EGIGA
1059			Define this to use GE link update with gigabit PHY.
1060			Define this if FTGMAC100 is connected to gigabit PHY.
1061			If your system has 10/100 PHY only, it might not occur
1062			wrong behavior. Because PHY usually return timeout or
1063			useless data when polling gigabit status and gigabit
1064			control registers. This behavior won't affect the
1065			correctnessof 10/100 link speed update.
1066
1067		CONFIG_SMC911X
1068		Support for SMSC's LAN911x and LAN921x chips
1069
1070			CONFIG_SMC911X_BASE
1071			Define this to hold the physical address
1072			of the device (I/O space)
1073
1074			CONFIG_SMC911X_32_BIT
1075			Define this if data bus is 32 bits
1076
1077			CONFIG_SMC911X_16_BIT
1078			Define this if data bus is 16 bits. If your processor
1079			automatically converts one 32 bit word to two 16 bit
1080			words you may also try CONFIG_SMC911X_32_BIT.
1081
1082		CONFIG_SH_ETHER
1083		Support for Renesas on-chip Ethernet controller
1084
1085			CONFIG_SH_ETHER_USE_PORT
1086			Define the number of ports to be used
1087
1088			CONFIG_SH_ETHER_PHY_ADDR
1089			Define the ETH PHY's address
1090
1091			CONFIG_SH_ETHER_CACHE_WRITEBACK
1092			If this option is set, the driver enables cache flush.
1093
1094- TPM Support:
1095		CONFIG_GENERIC_LPC_TPM
1096		Support for generic parallel port TPM devices. Only one device
1097		per system is supported at this time.
1098
1099			CONFIG_TPM_TIS_BASE_ADDRESS
1100			Base address where the generic TPM device is mapped
1101			to. Contemporary x86 systems usually map it at
1102			0xfed40000.
1103
1104- USB Support:
1105		At the moment only the UHCI host controller is
1106		supported (PIP405, MIP405, MPC5200); define
1107		CONFIG_USB_UHCI to enable it.
1108		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
1109		and define CONFIG_USB_STORAGE to enable the USB
1110		storage devices.
1111		Note:
1112		Supported are USB Keyboards and USB Floppy drives
1113		(TEAC FD-05PUB).
1114		MPC5200 USB requires additional defines:
1115			CONFIG_USB_CLOCK
1116				for 528 MHz Clock: 0x0001bbbb
1117			CONFIG_PSC3_USB
1118				for USB on PSC3
1119			CONFIG_USB_CONFIG
1120				for differential drivers: 0x00001000
1121				for single ended drivers: 0x00005000
1122				for differential drivers on PSC3: 0x00000100
1123				for single ended drivers on PSC3: 0x00004100
1124			CONFIG_SYS_USB_EVENT_POLL
1125				May be defined to allow interrupt polling
1126				instead of using asynchronous interrupts
1127
1128- USB Device:
1129		Define the below if you wish to use the USB console.
1130		Once firmware is rebuilt from a serial console issue the
1131		command "setenv stdin usbtty; setenv stdout usbtty" and
1132		attach your USB cable. The Unix command "dmesg" should print
1133		it has found a new device. The environment variable usbtty
1134		can be set to gserial or cdc_acm to enable your device to
1135		appear to a USB host as a Linux gserial device or a
1136		Common Device Class Abstract Control Model serial device.
1137		If you select usbtty = gserial you should be able to enumerate
1138		a Linux host by
1139		# modprobe usbserial vendor=0xVendorID product=0xProductID
1140		else if using cdc_acm, simply setting the environment
1141		variable usbtty to be cdc_acm should suffice. The following
1142		might be defined in YourBoardName.h
1143
1144			CONFIG_USB_DEVICE
1145			Define this to build a UDC device
1146
1147			CONFIG_USB_TTY
1148			Define this to have a tty type of device available to
1149			talk to the UDC device
1150
1151			CONFIG_USBD_HS
1152			Define this to enable the high speed support for usb
1153			device and usbtty. If this feature is enabled, a routine
1154			int is_usbd_high_speed(void)
1155			also needs to be defined by the driver to dynamically poll
1156			whether the enumeration has succeded at high speed or full
1157			speed.
1158
1159			CONFIG_SYS_CONSOLE_IS_IN_ENV
1160			Define this if you want stdin, stdout &/or stderr to
1161			be set to usbtty.
1162
1163			mpc8xx:
1164				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
1165				Derive USB clock from external clock "blah"
1166				- CONFIG_SYS_USB_EXTC_CLK 0x02
1167
1168				CONFIG_SYS_USB_BRG_CLK 0xBLAH
1169				Derive USB clock from brgclk
1170				- CONFIG_SYS_USB_BRG_CLK 0x04
1171
1172		If you have a USB-IF assigned VendorID then you may wish to
1173		define your own vendor specific values either in BoardName.h
1174		or directly in usbd_vendor_info.h. If you don't define
1175		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
1176		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
1177		should pretend to be a Linux device to it's target host.
1178
1179			CONFIG_USBD_MANUFACTURER
1180			Define this string as the name of your company for
1181			- CONFIG_USBD_MANUFACTURER "my company"
1182
1183			CONFIG_USBD_PRODUCT_NAME
1184			Define this string as the name of your product
1185			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
1186
1187			CONFIG_USBD_VENDORID
1188			Define this as your assigned Vendor ID from the USB
1189			Implementors Forum. This *must* be a genuine Vendor ID
1190			to avoid polluting the USB namespace.
1191			- CONFIG_USBD_VENDORID 0xFFFF
1192
1193			CONFIG_USBD_PRODUCTID
1194			Define this as the unique Product ID
1195			for your device
1196			- CONFIG_USBD_PRODUCTID 0xFFFF
1197
1198- ULPI Layer Support:
1199		The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
1200		the generic ULPI layer. The generic layer accesses the ULPI PHY
1201		via the platform viewport, so you need both the genric layer and
1202		the viewport enabled. Currently only Chipidea/ARC based
1203		viewport is supported.
1204		To enable the ULPI layer support, define CONFIG_USB_ULPI and
1205		CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
1206
1207- MMC Support:
1208		The MMC controller on the Intel PXA is supported. To
1209		enable this define CONFIG_MMC. The MMC can be
1210		accessed from the boot prompt by mapping the device
1211		to physical memory similar to flash. Command line is
1212		enabled with CONFIG_CMD_MMC. The MMC driver also works with
1213		the FAT fs. This is enabled with CONFIG_CMD_FAT.
1214
1215		CONFIG_SH_MMCIF
1216		Support for Renesas on-chip MMCIF controller
1217
1218			CONFIG_SH_MMCIF_ADDR
1219			Define the base address of MMCIF registers
1220
1221			CONFIG_SH_MMCIF_CLK
1222			Define the clock frequency for MMCIF
1223
1224- Journaling Flash filesystem support:
1225		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
1226		CONFIG_JFFS2_NAND_DEV
1227		Define these for a default partition on a NAND device
1228
1229		CONFIG_SYS_JFFS2_FIRST_SECTOR,
1230		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
1231		Define these for a default partition on a NOR device
1232
1233		CONFIG_SYS_JFFS_CUSTOM_PART
1234		Define this to create an own partition. You have to provide a
1235		function struct part_info* jffs2_part_info(int part_num)
1236
1237		If you define only one JFFS2 partition you may also want to
1238		#define CONFIG_SYS_JFFS_SINGLE_PART	1
1239		to disable the command chpart. This is the default when you
1240		have not defined a custom partition
1241
1242- FAT(File Allocation Table) filesystem write function support:
1243		CONFIG_FAT_WRITE
1244		Support for saving memory data as a file
1245		in FAT formatted partition
1246
1247- Keyboard Support:
1248		CONFIG_ISA_KEYBOARD
1249
1250		Define this to enable standard (PC-Style) keyboard
1251		support
1252
1253		CONFIG_I8042_KBD
1254		Standard PC keyboard driver with US (is default) and
1255		GERMAN key layout (switch via environment 'keymap=de') support.
1256		Export function i8042_kbd_init, i8042_tstc and i8042_getc
1257		for cfb_console. Supports cursor blinking.
1258
1259- Video support:
1260		CONFIG_VIDEO
1261
1262		Define this to enable video support (for output to
1263		video).
1264
1265		CONFIG_VIDEO_CT69000
1266
1267		Enable Chips & Technologies 69000 Video chip
1268
1269		CONFIG_VIDEO_SMI_LYNXEM
1270		Enable Silicon Motion SMI 712/710/810 Video chip. The
1271		video output is selected via environment 'videoout'
1272		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
1273		assumed.
1274
1275		For the CT69000 and SMI_LYNXEM drivers, videomode is
1276		selected via environment 'videomode'. Two different ways
1277		are possible:
1278		- "videomode=num"   'num' is a standard LiLo mode numbers.
1279		Following standard modes are supported	(* is default):
1280
1281		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
1282		-------------+---------------------------------------------
1283		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
1284		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
1285		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
1286		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
1287		-------------+---------------------------------------------
1288		(i.e. setenv videomode 317; saveenv; reset;)
1289
1290		- "videomode=bootargs" all the video parameters are parsed
1291		from the bootargs. (See drivers/video/videomodes.c)
1292
1293
1294		CONFIG_VIDEO_SED13806
1295		Enable Epson SED13806 driver. This driver supports 8bpp
1296		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
1297		or CONFIG_VIDEO_SED13806_16BPP
1298
1299		CONFIG_FSL_DIU_FB
1300		Enable the Freescale DIU video driver.	Reference boards for
1301		SOCs that have a DIU should define this macro to enable DIU
1302		support, and should also define these other macros:
1303
1304			CONFIG_SYS_DIU_ADDR
1305			CONFIG_VIDEO
1306			CONFIG_CMD_BMP
1307			CONFIG_CFB_CONSOLE
1308			CONFIG_VIDEO_SW_CURSOR
1309			CONFIG_VGA_AS_SINGLE_DEVICE
1310			CONFIG_VIDEO_LOGO
1311			CONFIG_VIDEO_BMP_LOGO
1312
1313		The DIU driver will look for the 'video-mode' environment
1314		variable, and if defined, enable the DIU as a console during
1315		boot.  See the documentation file README.video for a
1316		description of this variable.
1317
1318- Keyboard Support:
1319		CONFIG_KEYBOARD
1320
1321		Define this to enable a custom keyboard support.
1322		This simply calls drv_keyboard_init() which must be
1323		defined in your board-specific files.
1324		The only board using this so far is RBC823.
1325
1326- LCD Support:	CONFIG_LCD
1327
1328		Define this to enable LCD support (for output to LCD
1329		display); also select one of the supported displays
1330		by defining one of these:
1331
1332		CONFIG_ATMEL_LCD:
1333
1334			HITACHI TX09D70VM1CCA, 3.5", 240x320.
1335
1336		CONFIG_NEC_NL6448AC33:
1337
1338			NEC NL6448AC33-18. Active, color, single scan.
1339
1340		CONFIG_NEC_NL6448BC20
1341
1342			NEC NL6448BC20-08. 6.5", 640x480.
1343			Active, color, single scan.
1344
1345		CONFIG_NEC_NL6448BC33_54
1346
1347			NEC NL6448BC33-54. 10.4", 640x480.
1348			Active, color, single scan.
1349
1350		CONFIG_SHARP_16x9
1351
1352			Sharp 320x240. Active, color, single scan.
1353			It isn't 16x9, and I am not sure what it is.
1354
1355		CONFIG_SHARP_LQ64D341
1356
1357			Sharp LQ64D341 display, 640x480.
1358			Active, color, single scan.
1359
1360		CONFIG_HLD1045
1361
1362			HLD1045 display, 640x480.
1363			Active, color, single scan.
1364
1365		CONFIG_OPTREX_BW
1366
1367			Optrex	 CBL50840-2 NF-FW 99 22 M5
1368			or
1369			Hitachi	 LMG6912RPFC-00T
1370			or
1371			Hitachi	 SP14Q002
1372
1373			320x240. Black & white.
1374
1375		Normally display is black on white background; define
1376		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1377
1378- Splash Screen Support: CONFIG_SPLASH_SCREEN
1379
1380		If this option is set, the environment is checked for
1381		a variable "splashimage". If found, the usual display
1382		of logo, copyright and system information on the LCD
1383		is suppressed and the BMP image at the address
1384		specified in "splashimage" is loaded instead. The
1385		console is redirected to the "nulldev", too. This
1386		allows for a "silent" boot where a splash screen is
1387		loaded very quickly after power-on.
1388
1389		CONFIG_SPLASH_SCREEN_ALIGN
1390
1391		If this option is set the splash image can be freely positioned
1392		on the screen. Environment variable "splashpos" specifies the
1393		position as "x,y". If a positive number is given it is used as
1394		number of pixel from left/top. If a negative number is given it
1395		is used as number of pixel from right/bottom. You can also
1396		specify 'm' for centering the image.
1397
1398		Example:
1399		setenv splashpos m,m
1400			=> image at center of screen
1401
1402		setenv splashpos 30,20
1403			=> image at x = 30 and y = 20
1404
1405		setenv splashpos -10,m
1406			=> vertically centered image
1407			   at x = dspWidth - bmpWidth - 9
1408
1409- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1410
1411		If this option is set, additionally to standard BMP
1412		images, gzipped BMP images can be displayed via the
1413		splashscreen support or the bmp command.
1414
1415- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8
1416
1417		If this option is set, 8-bit RLE compressed BMP images
1418		can be displayed via the splashscreen support or the
1419		bmp command.
1420
1421- Compression support:
1422		CONFIG_BZIP2
1423
1424		If this option is set, support for bzip2 compressed
1425		images is included. If not, only uncompressed and gzip
1426		compressed images are supported.
1427
1428		NOTE: the bzip2 algorithm requires a lot of RAM, so
1429		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1430		be at least 4MB.
1431
1432		CONFIG_LZMA
1433
1434		If this option is set, support for lzma compressed
1435		images is included.
1436
1437		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1438		requires an amount of dynamic memory that is given by the
1439		formula:
1440
1441			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1442
1443		Where lc and lp stand for, respectively, Literal context bits
1444		and Literal pos bits.
1445
1446		This value is upper-bounded by 14MB in the worst case. Anyway,
1447		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1448		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1449		a very small buffer.
1450
1451		Use the lzmainfo tool to determinate the lc and lp values and
1452		then calculate the amount of needed dynamic memory (ensuring
1453		the appropriate CONFIG_SYS_MALLOC_LEN value).
1454
1455- MII/PHY support:
1456		CONFIG_PHY_ADDR
1457
1458		The address of PHY on MII bus.
1459
1460		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1461
1462		The clock frequency of the MII bus
1463
1464		CONFIG_PHY_GIGE
1465
1466		If this option is set, support for speed/duplex
1467		detection of gigabit PHY is included.
1468
1469		CONFIG_PHY_RESET_DELAY
1470
1471		Some PHY like Intel LXT971A need extra delay after
1472		reset before any MII register access is possible.
1473		For such PHY, set this option to the usec delay
1474		required. (minimum 300usec for LXT971A)
1475
1476		CONFIG_PHY_CMD_DELAY (ppc4xx)
1477
1478		Some PHY like Intel LXT971A need extra delay after
1479		command issued before MII status register can be read
1480
1481- Ethernet address:
1482		CONFIG_ETHADDR
1483		CONFIG_ETH1ADDR
1484		CONFIG_ETH2ADDR
1485		CONFIG_ETH3ADDR
1486		CONFIG_ETH4ADDR
1487		CONFIG_ETH5ADDR
1488
1489		Define a default value for Ethernet address to use
1490		for the respective Ethernet interface, in case this
1491		is not determined automatically.
1492
1493- IP address:
1494		CONFIG_IPADDR
1495
1496		Define a default value for the IP address to use for
1497		the default Ethernet interface, in case this is not
1498		determined through e.g. bootp.
1499		(Environment variable "ipaddr")
1500
1501- Server IP address:
1502		CONFIG_SERVERIP
1503
1504		Defines a default value for the IP address of a TFTP
1505		server to contact when using the "tftboot" command.
1506		(Environment variable "serverip")
1507
1508		CONFIG_KEEP_SERVERADDR
1509
1510		Keeps the server's MAC address, in the env 'serveraddr'
1511		for passing to bootargs (like Linux's netconsole option)
1512
1513- Gateway IP address:
1514		CONFIG_GATEWAYIP
1515
1516		Defines a default value for the IP address of the
1517		default router where packets to other networks are
1518		sent to.
1519		(Environment variable "gatewayip")
1520
1521- Subnet mask:
1522		CONFIG_NETMASK
1523
1524		Defines a default value for the subnet mask (or
1525		routing prefix) which is used to determine if an IP
1526		address belongs to the local subnet or needs to be
1527		forwarded through a router.
1528		(Environment variable "netmask")
1529
1530- Multicast TFTP Mode:
1531		CONFIG_MCAST_TFTP
1532
1533		Defines whether you want to support multicast TFTP as per
1534		rfc-2090; for example to work with atftp.  Lets lots of targets
1535		tftp down the same boot image concurrently.  Note: the Ethernet
1536		driver in use must provide a function: mcast() to join/leave a
1537		multicast group.
1538
1539- BOOTP Recovery Mode:
1540		CONFIG_BOOTP_RANDOM_DELAY
1541
1542		If you have many targets in a network that try to
1543		boot using BOOTP, you may want to avoid that all
1544		systems send out BOOTP requests at precisely the same
1545		moment (which would happen for instance at recovery
1546		from a power failure, when all systems will try to
1547		boot, thus flooding the BOOTP server. Defining
1548		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1549		inserted before sending out BOOTP requests. The
1550		following delays are inserted then:
1551
1552		1st BOOTP request:	delay 0 ... 1 sec
1553		2nd BOOTP request:	delay 0 ... 2 sec
1554		3rd BOOTP request:	delay 0 ... 4 sec
1555		4th and following
1556		BOOTP requests:		delay 0 ... 8 sec
1557
1558- DHCP Advanced Options:
1559		You can fine tune the DHCP functionality by defining
1560		CONFIG_BOOTP_* symbols:
1561
1562		CONFIG_BOOTP_SUBNETMASK
1563		CONFIG_BOOTP_GATEWAY
1564		CONFIG_BOOTP_HOSTNAME
1565		CONFIG_BOOTP_NISDOMAIN
1566		CONFIG_BOOTP_BOOTPATH
1567		CONFIG_BOOTP_BOOTFILESIZE
1568		CONFIG_BOOTP_DNS
1569		CONFIG_BOOTP_DNS2
1570		CONFIG_BOOTP_SEND_HOSTNAME
1571		CONFIG_BOOTP_NTPSERVER
1572		CONFIG_BOOTP_TIMEOFFSET
1573		CONFIG_BOOTP_VENDOREX
1574
1575		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1576		environment variable, not the BOOTP server.
1577
1578		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1579		serverip from a DHCP server, it is possible that more
1580		than one DNS serverip is offered to the client.
1581		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1582		serverip will be stored in the additional environment
1583		variable "dnsip2". The first DNS serverip is always
1584		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1585		is defined.
1586
1587		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1588		to do a dynamic update of a DNS server. To do this, they
1589		need the hostname of the DHCP requester.
1590		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1591		of the "hostname" environment variable is passed as
1592		option 12 to the DHCP server.
1593
1594		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1595
1596		A 32bit value in microseconds for a delay between
1597		receiving a "DHCP Offer" and sending the "DHCP Request".
1598		This fixes a problem with certain DHCP servers that don't
1599		respond 100% of the time to a "DHCP request". E.g. On an
1600		AT91RM9200 processor running at 180MHz, this delay needed
1601		to be *at least* 15,000 usec before a Windows Server 2003
1602		DHCP server would reply 100% of the time. I recommend at
1603		least 50,000 usec to be safe. The alternative is to hope
1604		that one of the retries will be successful but note that
1605		the DHCP timeout and retry process takes a longer than
1606		this delay.
1607
1608 - CDP Options:
1609		CONFIG_CDP_DEVICE_ID
1610
1611		The device id used in CDP trigger frames.
1612
1613		CONFIG_CDP_DEVICE_ID_PREFIX
1614
1615		A two character string which is prefixed to the MAC address
1616		of the device.
1617
1618		CONFIG_CDP_PORT_ID
1619
1620		A printf format string which contains the ascii name of
1621		the port. Normally is set to "eth%d" which sets
1622		eth0 for the first Ethernet, eth1 for the second etc.
1623
1624		CONFIG_CDP_CAPABILITIES
1625
1626		A 32bit integer which indicates the device capabilities;
1627		0x00000010 for a normal host which does not forwards.
1628
1629		CONFIG_CDP_VERSION
1630
1631		An ascii string containing the version of the software.
1632
1633		CONFIG_CDP_PLATFORM
1634
1635		An ascii string containing the name of the platform.
1636
1637		CONFIG_CDP_TRIGGER
1638
1639		A 32bit integer sent on the trigger.
1640
1641		CONFIG_CDP_POWER_CONSUMPTION
1642
1643		A 16bit integer containing the power consumption of the
1644		device in .1 of milliwatts.
1645
1646		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1647
1648		A byte containing the id of the VLAN.
1649
1650- Status LED:	CONFIG_STATUS_LED
1651
1652		Several configurations allow to display the current
1653		status using a LED. For instance, the LED will blink
1654		fast while running U-Boot code, stop blinking as
1655		soon as a reply to a BOOTP request was received, and
1656		start blinking slow once the Linux kernel is running
1657		(supported by a status LED driver in the Linux
1658		kernel). Defining CONFIG_STATUS_LED enables this
1659		feature in U-Boot.
1660
1661- CAN Support:	CONFIG_CAN_DRIVER
1662
1663		Defining CONFIG_CAN_DRIVER enables CAN driver support
1664		on those systems that support this (optional)
1665		feature, like the TQM8xxL modules.
1666
1667- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1668
1669		These enable I2C serial bus commands. Defining either of
1670		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1671		include the appropriate I2C driver for the selected CPU.
1672
1673		This will allow you to use i2c commands at the u-boot
1674		command line (as long as you set CONFIG_CMD_I2C in
1675		CONFIG_COMMANDS) and communicate with i2c based realtime
1676		clock chips. See common/cmd_i2c.c for a description of the
1677		command line interface.
1678
1679		CONFIG_HARD_I2C selects a hardware I2C controller.
1680
1681		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1682		bit-banging) driver instead of CPM or similar hardware
1683		support for I2C.
1684
1685		There are several other quantities that must also be
1686		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1687
1688		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1689		to be the frequency (in Hz) at which you wish your i2c bus
1690		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1691		the CPU's i2c node address).
1692
1693		Now, the u-boot i2c code for the mpc8xx
1694		(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node
1695		and so its address should therefore be cleared to 0 (See,
1696		eg, MPC823e User's Manual p.16-473). So, set
1697		CONFIG_SYS_I2C_SLAVE to 0.
1698
1699		CONFIG_SYS_I2C_INIT_MPC5XXX
1700
1701		When a board is reset during an i2c bus transfer
1702		chips might think that the current transfer is still
1703		in progress.  Reset the slave devices by sending start
1704		commands until the slave device responds.
1705
1706		That's all that's required for CONFIG_HARD_I2C.
1707
1708		If you use the software i2c interface (CONFIG_SOFT_I2C)
1709		then the following macros need to be defined (examples are
1710		from include/configs/lwmon.h):
1711
1712		I2C_INIT
1713
1714		(Optional). Any commands necessary to enable the I2C
1715		controller or configure ports.
1716
1717		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1718
1719		I2C_PORT
1720
1721		(Only for MPC8260 CPU). The I/O port to use (the code
1722		assumes both bits are on the same port). Valid values
1723		are 0..3 for ports A..D.
1724
1725		I2C_ACTIVE
1726
1727		The code necessary to make the I2C data line active
1728		(driven).  If the data line is open collector, this
1729		define can be null.
1730
1731		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1732
1733		I2C_TRISTATE
1734
1735		The code necessary to make the I2C data line tri-stated
1736		(inactive).  If the data line is open collector, this
1737		define can be null.
1738
1739		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1740
1741		I2C_READ
1742
1743		Code that returns TRUE if the I2C data line is high,
1744		FALSE if it is low.
1745
1746		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1747
1748		I2C_SDA(bit)
1749
1750		If <bit> is TRUE, sets the I2C data line high. If it
1751		is FALSE, it clears it (low).
1752
1753		eg: #define I2C_SDA(bit) \
1754			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1755			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1756
1757		I2C_SCL(bit)
1758
1759		If <bit> is TRUE, sets the I2C clock line high. If it
1760		is FALSE, it clears it (low).
1761
1762		eg: #define I2C_SCL(bit) \
1763			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1764			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1765
1766		I2C_DELAY
1767
1768		This delay is invoked four times per clock cycle so this
1769		controls the rate of data transfer.  The data rate thus
1770		is 1 / (I2C_DELAY * 4). Often defined to be something
1771		like:
1772
1773		#define I2C_DELAY  udelay(2)
1774
1775		CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1776
1777		If your arch supports the generic GPIO framework (asm/gpio.h),
1778		then you may alternatively define the two GPIOs that are to be
1779		used as SCL / SDA.  Any of the previous I2C_xxx macros will
1780		have GPIO-based defaults assigned to them as appropriate.
1781
1782		You should define these to the GPIO value as given directly to
1783		the generic GPIO functions.
1784
1785		CONFIG_SYS_I2C_INIT_BOARD
1786
1787		When a board is reset during an i2c bus transfer
1788		chips might think that the current transfer is still
1789		in progress. On some boards it is possible to access
1790		the i2c SCLK line directly, either by using the
1791		processor pin as a GPIO or by having a second pin
1792		connected to the bus. If this option is defined a
1793		custom i2c_init_board() routine in boards/xxx/board.c
1794		is run early in the boot sequence.
1795
1796		CONFIG_SYS_I2C_BOARD_LATE_INIT
1797
1798		An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is
1799		defined a custom i2c_board_late_init() routine in
1800		boards/xxx/board.c is run AFTER the operations in i2c_init()
1801		is completed. This callpoint can be used to unreset i2c bus
1802		using CPU i2c controller register accesses for CPUs whose i2c
1803		controller provide such a method. It is called at the end of
1804		i2c_init() to allow i2c_init operations to setup the i2c bus
1805		controller on the CPU (e.g. setting bus speed & slave address).
1806
1807		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1808
1809		This option enables configuration of bi_iic_fast[] flags
1810		in u-boot bd_info structure based on u-boot environment
1811		variable "i2cfast". (see also i2cfast)
1812
1813		CONFIG_I2C_MULTI_BUS
1814
1815		This option allows the use of multiple I2C buses, each of which
1816		must have a controller.	 At any point in time, only one bus is
1817		active.	 To switch to a different bus, use the 'i2c dev' command.
1818		Note that bus numbering is zero-based.
1819
1820		CONFIG_SYS_I2C_NOPROBES
1821
1822		This option specifies a list of I2C devices that will be skipped
1823		when the 'i2c probe' command is issued.	 If CONFIG_I2C_MULTI_BUS
1824		is set, specify a list of bus-device pairs.  Otherwise, specify
1825		a 1D array of device addresses
1826
1827		e.g.
1828			#undef	CONFIG_I2C_MULTI_BUS
1829			#define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1830
1831		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1832
1833			#define CONFIG_I2C_MULTI_BUS
1834			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1835
1836		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1837
1838		CONFIG_SYS_SPD_BUS_NUM
1839
1840		If defined, then this indicates the I2C bus number for DDR SPD.
1841		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1842
1843		CONFIG_SYS_RTC_BUS_NUM
1844
1845		If defined, then this indicates the I2C bus number for the RTC.
1846		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1847
1848		CONFIG_SYS_DTT_BUS_NUM
1849
1850		If defined, then this indicates the I2C bus number for the DTT.
1851		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1852
1853		CONFIG_SYS_I2C_DTT_ADDR:
1854
1855		If defined, specifies the I2C address of the DTT device.
1856		If not defined, then U-Boot uses predefined value for
1857		specified DTT device.
1858
1859		CONFIG_FSL_I2C
1860
1861		Define this option if you want to use Freescale's I2C driver in
1862		drivers/i2c/fsl_i2c.c.
1863
1864		CONFIG_I2C_MUX
1865
1866		Define this option if you have I2C devices reached over 1 .. n
1867		I2C Muxes like the pca9544a. This option addes a new I2C
1868		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1869		new I2C Bus to the existing I2C Busses. If you select the
1870		new Bus with "i2c dev", u-bbot sends first the commandos for
1871		the muxes to activate this new "bus".
1872
1873		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1874		feature!
1875
1876		Example:
1877		Adding a new I2C Bus reached over 2 pca9544a muxes
1878			The First mux with address 70 and channel 6
1879			The Second mux with address 71 and channel 4
1880
1881		=> i2c bus pca9544a:70:6:pca9544a:71:4
1882
1883		Use the "i2c bus" command without parameter, to get a list
1884		of I2C Busses with muxes:
1885
1886		=> i2c bus
1887		Busses reached over muxes:
1888		Bus ID: 2
1889		  reached over Mux(es):
1890		    pca9544a@70 ch: 4
1891		Bus ID: 3
1892		  reached over Mux(es):
1893		    pca9544a@70 ch: 6
1894		    pca9544a@71 ch: 4
1895		=>
1896
1897		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1898		u-boot first sends the command to the mux@70 to enable
1899		channel 6, and then the command to the mux@71 to enable
1900		the channel 4.
1901
1902		After that, you can use the "normal" i2c commands as
1903		usual to communicate with your I2C devices behind
1904		the 2 muxes.
1905
1906		This option is actually implemented for the bitbanging
1907		algorithm in common/soft_i2c.c and for the Hardware I2C
1908		Bus on the MPC8260. But it should be not so difficult
1909		to add this option to other architectures.
1910
1911		CONFIG_SOFT_I2C_READ_REPEATED_START
1912
1913		defining this will force the i2c_read() function in
1914		the soft_i2c driver to perform an I2C repeated start
1915		between writing the address pointer and reading the
1916		data.  If this define is omitted the default behaviour
1917		of doing a stop-start sequence will be used.  Most I2C
1918		devices can use either method, but some require one or
1919		the other.
1920
1921- SPI Support:	CONFIG_SPI
1922
1923		Enables SPI driver (so far only tested with
1924		SPI EEPROM, also an instance works with Crystal A/D and
1925		D/As on the SACSng board)
1926
1927		CONFIG_SH_SPI
1928
1929		Enables the driver for SPI controller on SuperH. Currently
1930		only SH7757 is supported.
1931
1932		CONFIG_SPI_X
1933
1934		Enables extended (16-bit) SPI EEPROM addressing.
1935		(symmetrical to CONFIG_I2C_X)
1936
1937		CONFIG_SOFT_SPI
1938
1939		Enables a software (bit-bang) SPI driver rather than
1940		using hardware support. This is a general purpose
1941		driver that only requires three general I/O port pins
1942		(two outputs, one input) to function. If this is
1943		defined, the board configuration must define several
1944		SPI configuration items (port pins to use, etc). For
1945		an example, see include/configs/sacsng.h.
1946
1947		CONFIG_HARD_SPI
1948
1949		Enables a hardware SPI driver for general-purpose reads
1950		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1951		must define a list of chip-select function pointers.
1952		Currently supported on some MPC8xxx processors.	 For an
1953		example, see include/configs/mpc8349emds.h.
1954
1955		CONFIG_MXC_SPI
1956
1957		Enables the driver for the SPI controllers on i.MX and MXC
1958		SoCs. Currently i.MX31/35/51 are supported.
1959
1960- FPGA Support: CONFIG_FPGA
1961
1962		Enables FPGA subsystem.
1963
1964		CONFIG_FPGA_<vendor>
1965
1966		Enables support for specific chip vendors.
1967		(ALTERA, XILINX)
1968
1969		CONFIG_FPGA_<family>
1970
1971		Enables support for FPGA family.
1972		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1973
1974		CONFIG_FPGA_COUNT
1975
1976		Specify the number of FPGA devices to support.
1977
1978		CONFIG_SYS_FPGA_PROG_FEEDBACK
1979
1980		Enable printing of hash marks during FPGA configuration.
1981
1982		CONFIG_SYS_FPGA_CHECK_BUSY
1983
1984		Enable checks on FPGA configuration interface busy
1985		status by the configuration function. This option
1986		will require a board or device specific function to
1987		be written.
1988
1989		CONFIG_FPGA_DELAY
1990
1991		If defined, a function that provides delays in the FPGA
1992		configuration driver.
1993
1994		CONFIG_SYS_FPGA_CHECK_CTRLC
1995		Allow Control-C to interrupt FPGA configuration
1996
1997		CONFIG_SYS_FPGA_CHECK_ERROR
1998
1999		Check for configuration errors during FPGA bitfile
2000		loading. For example, abort during Virtex II
2001		configuration if the INIT_B line goes low (which
2002		indicated a CRC error).
2003
2004		CONFIG_SYS_FPGA_WAIT_INIT
2005
2006		Maximum time to wait for the INIT_B line to deassert
2007		after PROB_B has been deasserted during a Virtex II
2008		FPGA configuration sequence. The default time is 500
2009		ms.
2010
2011		CONFIG_SYS_FPGA_WAIT_BUSY
2012
2013		Maximum time to wait for BUSY to deassert during
2014		Virtex II FPGA configuration. The default is 5 ms.
2015
2016		CONFIG_SYS_FPGA_WAIT_CONFIG
2017
2018		Time to wait after FPGA configuration. The default is
2019		200 ms.
2020
2021- Configuration Management:
2022		CONFIG_IDENT_STRING
2023
2024		If defined, this string will be added to the U-Boot
2025		version information (U_BOOT_VERSION)
2026
2027- Vendor Parameter Protection:
2028
2029		U-Boot considers the values of the environment
2030		variables "serial#" (Board Serial Number) and
2031		"ethaddr" (Ethernet Address) to be parameters that
2032		are set once by the board vendor / manufacturer, and
2033		protects these variables from casual modification by
2034		the user. Once set, these variables are read-only,
2035		and write or delete attempts are rejected. You can
2036		change this behaviour:
2037
2038		If CONFIG_ENV_OVERWRITE is #defined in your config
2039		file, the write protection for vendor parameters is
2040		completely disabled. Anybody can change or delete
2041		these parameters.
2042
2043		Alternatively, if you #define _both_ CONFIG_ETHADDR
2044		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
2045		Ethernet address is installed in the environment,
2046		which can be changed exactly ONCE by the user. [The
2047		serial# is unaffected by this, i. e. it remains
2048		read-only.]
2049
2050- Protected RAM:
2051		CONFIG_PRAM
2052
2053		Define this variable to enable the reservation of
2054		"protected RAM", i. e. RAM which is not overwritten
2055		by U-Boot. Define CONFIG_PRAM to hold the number of
2056		kB you want to reserve for pRAM. You can overwrite
2057		this default value by defining an environment
2058		variable "pram" to the number of kB you want to
2059		reserve. Note that the board info structure will
2060		still show the full amount of RAM. If pRAM is
2061		reserved, a new environment variable "mem" will
2062		automatically be defined to hold the amount of
2063		remaining RAM in a form that can be passed as boot
2064		argument to Linux, for instance like that:
2065
2066			setenv bootargs ... mem=\${mem}
2067			saveenv
2068
2069		This way you can tell Linux not to use this memory,
2070		either, which results in a memory region that will
2071		not be affected by reboots.
2072
2073		*WARNING* If your board configuration uses automatic
2074		detection of the RAM size, you must make sure that
2075		this memory test is non-destructive. So far, the
2076		following board configurations are known to be
2077		"pRAM-clean":
2078
2079			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
2080			HERMES, IP860, RPXlite, LWMON, LANTEC,
2081			FLAGADM, TQM8260
2082
2083- Error Recovery:
2084		CONFIG_PANIC_HANG
2085
2086		Define this variable to stop the system in case of a
2087		fatal error, so that you have to reset it manually.
2088		This is probably NOT a good idea for an embedded
2089		system where you want the system to reboot
2090		automatically as fast as possible, but it may be
2091		useful during development since you can try to debug
2092		the conditions that lead to the situation.
2093
2094		CONFIG_NET_RETRY_COUNT
2095
2096		This variable defines the number of retries for
2097		network operations like ARP, RARP, TFTP, or BOOTP
2098		before giving up the operation. If not defined, a
2099		default value of 5 is used.
2100
2101		CONFIG_ARP_TIMEOUT
2102
2103		Timeout waiting for an ARP reply in milliseconds.
2104
2105- Command Interpreter:
2106		CONFIG_AUTO_COMPLETE
2107
2108		Enable auto completion of commands using TAB.
2109
2110		Note that this feature has NOT been implemented yet
2111		for the "hush" shell.
2112
2113
2114		CONFIG_SYS_HUSH_PARSER
2115
2116		Define this variable to enable the "hush" shell (from
2117		Busybox) as command line interpreter, thus enabling
2118		powerful command line syntax like
2119		if...then...else...fi conditionals or `&&' and '||'
2120		constructs ("shell scripts").
2121
2122		If undefined, you get the old, much simpler behaviour
2123		with a somewhat smaller memory footprint.
2124
2125
2126		CONFIG_SYS_PROMPT_HUSH_PS2
2127
2128		This defines the secondary prompt string, which is
2129		printed when the command interpreter needs more input
2130		to complete a command. Usually "> ".
2131
2132	Note:
2133
2134		In the current implementation, the local variables
2135		space and global environment variables space are
2136		separated. Local variables are those you define by
2137		simply typing `name=value'. To access a local
2138		variable later on, you have write `$name' or
2139		`${name}'; to execute the contents of a variable
2140		directly type `$name' at the command prompt.
2141
2142		Global environment variables are those you use
2143		setenv/printenv to work with. To run a command stored
2144		in such a variable, you need to use the run command,
2145		and you must not use the '$' sign to access them.
2146
2147		To store commands and special characters in a
2148		variable, please use double quotation marks
2149		surrounding the whole text of the variable, instead
2150		of the backslashes before semicolons and special
2151		symbols.
2152
2153- Commandline Editing and History:
2154		CONFIG_CMDLINE_EDITING
2155
2156		Enable editing and History functions for interactive
2157		commandline input operations
2158
2159- Default Environment:
2160		CONFIG_EXTRA_ENV_SETTINGS
2161
2162		Define this to contain any number of null terminated
2163		strings (variable = value pairs) that will be part of
2164		the default environment compiled into the boot image.
2165
2166		For example, place something like this in your
2167		board's config file:
2168
2169		#define CONFIG_EXTRA_ENV_SETTINGS \
2170			"myvar1=value1\0" \
2171			"myvar2=value2\0"
2172
2173		Warning: This method is based on knowledge about the
2174		internal format how the environment is stored by the
2175		U-Boot code. This is NOT an official, exported
2176		interface! Although it is unlikely that this format
2177		will change soon, there is no guarantee either.
2178		You better know what you are doing here.
2179
2180		Note: overly (ab)use of the default environment is
2181		discouraged. Make sure to check other ways to preset
2182		the environment like the "source" command or the
2183		boot command first.
2184
2185- DataFlash Support:
2186		CONFIG_HAS_DATAFLASH
2187
2188		Defining this option enables DataFlash features and
2189		allows to read/write in Dataflash via the standard
2190		commands cp, md...
2191
2192- Serial Flash support
2193		CONFIG_CMD_SF
2194
2195		Defining this option enables SPI flash commands
2196		'sf probe/read/write/erase/update'.
2197
2198		Usage requires an initial 'probe' to define the serial
2199		flash parameters, followed by read/write/erase/update
2200		commands.
2201
2202		The following defaults may be provided by the platform
2203		to handle the common case when only a single serial
2204		flash is present on the system.
2205
2206		CONFIG_SF_DEFAULT_BUS		Bus identifier
2207		CONFIG_SF_DEFAULT_CS		Chip-select
2208		CONFIG_SF_DEFAULT_MODE 		(see include/spi.h)
2209		CONFIG_SF_DEFAULT_SPEED		in Hz
2210
2211- SystemACE Support:
2212		CONFIG_SYSTEMACE
2213
2214		Adding this option adds support for Xilinx SystemACE
2215		chips attached via some sort of local bus. The address
2216		of the chip must also be defined in the
2217		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
2218
2219		#define CONFIG_SYSTEMACE
2220		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
2221
2222		When SystemACE support is added, the "ace" device type
2223		becomes available to the fat commands, i.e. fatls.
2224
2225- TFTP Fixed UDP Port:
2226		CONFIG_TFTP_PORT
2227
2228		If this is defined, the environment variable tftpsrcp
2229		is used to supply the TFTP UDP source port value.
2230		If tftpsrcp isn't defined, the normal pseudo-random port
2231		number generator is used.
2232
2233		Also, the environment variable tftpdstp is used to supply
2234		the TFTP UDP destination port value.  If tftpdstp isn't
2235		defined, the normal port 69 is used.
2236
2237		The purpose for tftpsrcp is to allow a TFTP server to
2238		blindly start the TFTP transfer using the pre-configured
2239		target IP address and UDP port. This has the effect of
2240		"punching through" the (Windows XP) firewall, allowing
2241		the remainder of the TFTP transfer to proceed normally.
2242		A better solution is to properly configure the firewall,
2243		but sometimes that is not allowed.
2244
2245- Show boot progress:
2246		CONFIG_SHOW_BOOT_PROGRESS
2247
2248		Defining this option allows to add some board-
2249		specific code (calling a user-provided function
2250		"show_boot_progress(int)") that enables you to show
2251		the system's boot progress on some display (for
2252		example, some LED's) on your board. At the moment,
2253		the following checkpoints are implemented:
2254
2255- Detailed boot stage timing
2256		CONFIG_BOOTSTAGE
2257		Define this option to get detailed timing of each stage
2258		of the boot process.
2259
2260		CONFIG_BOOTSTAGE_USER_COUNT
2261		This is the number of available user bootstage records.
2262		Each time you call bootstage_mark(BOOTSTAGE_ID_ALLOC, ...)
2263		a new ID will be allocated from this stash. If you exceed
2264		the limit, recording will stop.
2265
2266		CONFIG_BOOTSTAGE_REPORT
2267		Define this to print a report before boot, similar to this:
2268
2269		Timer summary in microseconds:
2270		       Mark    Elapsed  Stage
2271			  0          0  reset
2272		  3,575,678  3,575,678  board_init_f start
2273		  3,575,695         17  arch_cpu_init A9
2274		  3,575,777         82  arch_cpu_init done
2275		  3,659,598     83,821  board_init_r start
2276		  3,910,375    250,777  main_loop
2277		 29,916,167 26,005,792  bootm_start
2278		 30,361,327    445,160  start_kernel
2279
2280Legacy uImage format:
2281
2282  Arg	Where			When
2283    1	common/cmd_bootm.c	before attempting to boot an image
2284   -1	common/cmd_bootm.c	Image header has bad	 magic number
2285    2	common/cmd_bootm.c	Image header has correct magic number
2286   -2	common/cmd_bootm.c	Image header has bad	 checksum
2287    3	common/cmd_bootm.c	Image header has correct checksum
2288   -3	common/cmd_bootm.c	Image data   has bad	 checksum
2289    4	common/cmd_bootm.c	Image data   has correct checksum
2290   -4	common/cmd_bootm.c	Image is for unsupported architecture
2291    5	common/cmd_bootm.c	Architecture check OK
2292   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
2293    6	common/cmd_bootm.c	Image Type check OK
2294   -6	common/cmd_bootm.c	gunzip uncompression error
2295   -7	common/cmd_bootm.c	Unimplemented compression type
2296    7	common/cmd_bootm.c	Uncompression OK
2297    8	common/cmd_bootm.c	No uncompress/copy overwrite error
2298   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
2299
2300    9	common/image.c		Start initial ramdisk verification
2301  -10	common/image.c		Ramdisk header has bad	   magic number
2302  -11	common/image.c		Ramdisk header has bad	   checksum
2303   10	common/image.c		Ramdisk header is OK
2304  -12	common/image.c		Ramdisk data   has bad	   checksum
2305   11	common/image.c		Ramdisk data   has correct checksum
2306   12	common/image.c		Ramdisk verification complete, start loading
2307  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
2308   13	common/image.c		Start multifile image verification
2309   14	common/image.c		No initial ramdisk, no multifile, continue.
2310
2311   15	arch/<arch>/lib/bootm.c All preparation done, transferring control to OS
2312
2313  -30	arch/powerpc/lib/board.c	Fatal error, hang the system
2314  -31	post/post.c		POST test failed, detected by post_output_backlog()
2315  -32	post/post.c		POST test failed, detected by post_run_single()
2316
2317   34	common/cmd_doc.c	before loading a Image from a DOC device
2318  -35	common/cmd_doc.c	Bad usage of "doc" command
2319   35	common/cmd_doc.c	correct usage of "doc" command
2320  -36	common/cmd_doc.c	No boot device
2321   36	common/cmd_doc.c	correct boot device
2322  -37	common/cmd_doc.c	Unknown Chip ID on boot device
2323   37	common/cmd_doc.c	correct chip ID found, device available
2324  -38	common/cmd_doc.c	Read Error on boot device
2325   38	common/cmd_doc.c	reading Image header from DOC device OK
2326  -39	common/cmd_doc.c	Image header has bad magic number
2327   39	common/cmd_doc.c	Image header has correct magic number
2328  -40	common/cmd_doc.c	Error reading Image from DOC device
2329   40	common/cmd_doc.c	Image header has correct magic number
2330   41	common/cmd_ide.c	before loading a Image from a IDE device
2331  -42	common/cmd_ide.c	Bad usage of "ide" command
2332   42	common/cmd_ide.c	correct usage of "ide" command
2333  -43	common/cmd_ide.c	No boot device
2334   43	common/cmd_ide.c	boot device found
2335  -44	common/cmd_ide.c	Device not available
2336   44	common/cmd_ide.c	Device available
2337  -45	common/cmd_ide.c	wrong partition selected
2338   45	common/cmd_ide.c	partition selected
2339  -46	common/cmd_ide.c	Unknown partition table
2340   46	common/cmd_ide.c	valid partition table found
2341  -47	common/cmd_ide.c	Invalid partition type
2342   47	common/cmd_ide.c	correct partition type
2343  -48	common/cmd_ide.c	Error reading Image Header on boot device
2344   48	common/cmd_ide.c	reading Image Header from IDE device OK
2345  -49	common/cmd_ide.c	Image header has bad magic number
2346   49	common/cmd_ide.c	Image header has correct magic number
2347  -50	common/cmd_ide.c	Image header has bad	 checksum
2348   50	common/cmd_ide.c	Image header has correct checksum
2349  -51	common/cmd_ide.c	Error reading Image from IDE device
2350   51	common/cmd_ide.c	reading Image from IDE device OK
2351   52	common/cmd_nand.c	before loading a Image from a NAND device
2352  -53	common/cmd_nand.c	Bad usage of "nand" command
2353   53	common/cmd_nand.c	correct usage of "nand" command
2354  -54	common/cmd_nand.c	No boot device
2355   54	common/cmd_nand.c	boot device found
2356  -55	common/cmd_nand.c	Unknown Chip ID on boot device
2357   55	common/cmd_nand.c	correct chip ID found, device available
2358  -56	common/cmd_nand.c	Error reading Image Header on boot device
2359   56	common/cmd_nand.c	reading Image Header from NAND device OK
2360  -57	common/cmd_nand.c	Image header has bad magic number
2361   57	common/cmd_nand.c	Image header has correct magic number
2362  -58	common/cmd_nand.c	Error reading Image from NAND device
2363   58	common/cmd_nand.c	reading Image from NAND device OK
2364
2365  -60	common/env_common.c	Environment has a bad CRC, using default
2366
2367   64	net/eth.c		starting with Ethernet configuration.
2368  -64	net/eth.c		no Ethernet found.
2369   65	net/eth.c		Ethernet found.
2370
2371  -80	common/cmd_net.c	usage wrong
2372   80	common/cmd_net.c	before calling NetLoop()
2373  -81	common/cmd_net.c	some error in NetLoop() occurred
2374   81	common/cmd_net.c	NetLoop() back without error
2375  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
2376   82	common/cmd_net.c	trying automatic boot
2377   83	common/cmd_net.c	running "source" command
2378  -83	common/cmd_net.c	some error in automatic boot or "source" command
2379   84	common/cmd_net.c	end without errors
2380
2381FIT uImage format:
2382
2383  Arg	Where			When
2384  100	common/cmd_bootm.c	Kernel FIT Image has correct format
2385 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
2386  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
2387 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
2388  102	common/cmd_bootm.c	Kernel unit name specified
2389 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
2390  103	common/cmd_bootm.c	Found configuration node
2391  104	common/cmd_bootm.c	Got kernel subimage node offset
2392 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
2393  105	common/cmd_bootm.c	Kernel subimage hash verification OK
2394 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
2395  106	common/cmd_bootm.c	Architecture check OK
2396 -106	common/cmd_bootm.c	Kernel subimage has wrong type
2397  107	common/cmd_bootm.c	Kernel subimage type OK
2398 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
2399  108	common/cmd_bootm.c	Got kernel subimage data/size
2400 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
2401 -109	common/cmd_bootm.c	Can't get kernel subimage type
2402 -110	common/cmd_bootm.c	Can't get kernel subimage comp
2403 -111	common/cmd_bootm.c	Can't get kernel subimage os
2404 -112	common/cmd_bootm.c	Can't get kernel subimage load address
2405 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
2406
2407  120	common/image.c		Start initial ramdisk verification
2408 -120	common/image.c		Ramdisk FIT image has incorrect format
2409  121	common/image.c		Ramdisk FIT image has correct format
2410  122	common/image.c		No ramdisk subimage unit name, using configuration
2411 -122	common/image.c		Can't get configuration for ramdisk subimage
2412  123	common/image.c		Ramdisk unit name specified
2413 -124	common/image.c		Can't get ramdisk subimage node offset
2414  125	common/image.c		Got ramdisk subimage node offset
2415 -125	common/image.c		Ramdisk subimage hash verification failed
2416  126	common/image.c		Ramdisk subimage hash verification OK
2417 -126	common/image.c		Ramdisk subimage for unsupported architecture
2418  127	common/image.c		Architecture check OK
2419 -127	common/image.c		Can't get ramdisk subimage data/size
2420  128	common/image.c		Got ramdisk subimage data/size
2421  129	common/image.c		Can't get ramdisk load address
2422 -129	common/image.c		Got ramdisk load address
2423
2424 -130	common/cmd_doc.c	Incorrect FIT image format
2425  131	common/cmd_doc.c	FIT image format OK
2426
2427 -140	common/cmd_ide.c	Incorrect FIT image format
2428  141	common/cmd_ide.c	FIT image format OK
2429
2430 -150	common/cmd_nand.c	Incorrect FIT image format
2431  151	common/cmd_nand.c	FIT image format OK
2432
2433- Standalone program support:
2434		CONFIG_STANDALONE_LOAD_ADDR
2435
2436		This option defines a board specific value for the
2437		address where standalone program gets loaded, thus
2438		overwriting the architecture dependent default
2439		settings.
2440
2441- Frame Buffer Address:
2442		CONFIG_FB_ADDR
2443
2444		Define CONFIG_FB_ADDR if you want to use specific
2445		address for frame buffer.
2446		Then system will reserve the frame buffer address to
2447		defined address instead of lcd_setmem (this function
2448		grabs the memory for frame buffer by panel's size).
2449
2450		Please see board_init_f function.
2451
2452- Automatic software updates via TFTP server
2453		CONFIG_UPDATE_TFTP
2454		CONFIG_UPDATE_TFTP_CNT_MAX
2455		CONFIG_UPDATE_TFTP_MSEC_MAX
2456
2457		These options enable and control the auto-update feature;
2458		for a more detailed description refer to doc/README.update.
2459
2460- MTD Support (mtdparts command, UBI support)
2461		CONFIG_MTD_DEVICE
2462
2463		Adds the MTD device infrastructure from the Linux kernel.
2464		Needed for mtdparts command support.
2465
2466		CONFIG_MTD_PARTITIONS
2467
2468		Adds the MTD partitioning infrastructure from the Linux
2469		kernel. Needed for UBI support.
2470
2471- SPL framework
2472		CONFIG_SPL
2473		Enable building of SPL globally.
2474
2475		CONFIG_SPL_TEXT_BASE
2476		TEXT_BASE for linking the SPL binary.
2477
2478		CONFIG_SPL_LDSCRIPT
2479		LDSCRIPT for linking the SPL binary.
2480
2481		CONFIG_SPL_LIBCOMMON_SUPPORT
2482		Support for common/libcommon.o in SPL binary
2483
2484		CONFIG_SPL_LIBDISK_SUPPORT
2485		Support for disk/libdisk.o in SPL binary
2486
2487		CONFIG_SPL_I2C_SUPPORT
2488		Support for drivers/i2c/libi2c.o in SPL binary
2489
2490		CONFIG_SPL_GPIO_SUPPORT
2491		Support for drivers/gpio/libgpio.o in SPL binary
2492
2493		CONFIG_SPL_MMC_SUPPORT
2494		Support for drivers/mmc/libmmc.o in SPL binary
2495
2496		CONFIG_SPL_SERIAL_SUPPORT
2497		Support for drivers/serial/libserial.o in SPL binary
2498
2499		CONFIG_SPL_SPI_FLASH_SUPPORT
2500		Support for drivers/mtd/spi/libspi_flash.o in SPL binary
2501
2502		CONFIG_SPL_SPI_SUPPORT
2503		Support for drivers/spi/libspi.o in SPL binary
2504
2505		CONFIG_SPL_FAT_SUPPORT
2506		Support for fs/fat/libfat.o in SPL binary
2507
2508		CONFIG_SPL_LIBGENERIC_SUPPORT
2509		Support for lib/libgeneric.o in SPL binary
2510
2511Modem Support:
2512--------------
2513
2514[so far only for SMDK2400 boards]
2515
2516- Modem support enable:
2517		CONFIG_MODEM_SUPPORT
2518
2519- RTS/CTS Flow control enable:
2520		CONFIG_HWFLOW
2521
2522- Modem debug support:
2523		CONFIG_MODEM_SUPPORT_DEBUG
2524
2525		Enables debugging stuff (char screen[1024], dbg())
2526		for modem support. Useful only with BDI2000.
2527
2528- Interrupt support (PPC):
2529
2530		There are common interrupt_init() and timer_interrupt()
2531		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
2532		for CPU specific initialization. interrupt_init_cpu()
2533		should set decrementer_count to appropriate value. If
2534		CPU resets decrementer automatically after interrupt
2535		(ppc4xx) it should set decrementer_count to zero.
2536		timer_interrupt() calls timer_interrupt_cpu() for CPU
2537		specific handling. If board has watchdog / status_led
2538		/ other_activity_monitor it works automatically from
2539		general timer_interrupt().
2540
2541- General:
2542
2543		In the target system modem support is enabled when a
2544		specific key (key combination) is pressed during
2545		power-on. Otherwise U-Boot will boot normally
2546		(autoboot). The key_pressed() function is called from
2547		board_init(). Currently key_pressed() is a dummy
2548		function, returning 1 and thus enabling modem
2549		initialization.
2550
2551		If there are no modem init strings in the
2552		environment, U-Boot proceed to autoboot; the
2553		previous output (banner, info printfs) will be
2554		suppressed, though.
2555
2556		See also: doc/README.Modem
2557
2558Board initialization settings:
2559------------------------------
2560
2561During Initialization u-boot calls a number of board specific functions
2562to allow the preparation of board specific prerequisites, e.g. pin setup
2563before drivers are initialized. To enable these callbacks the
2564following configuration macros have to be defined. Currently this is
2565architecture specific, so please check arch/your_architecture/lib/board.c
2566typically in board_init_f() and board_init_r().
2567
2568- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
2569- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
2570- CONFIG_BOARD_LATE_INIT: Call board_late_init()
2571- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
2572
2573Configuration Settings:
2574-----------------------
2575
2576- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2577		undefine this when you're short of memory.
2578
2579- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
2580		width of the commands listed in the 'help' command output.
2581
2582- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2583		prompt for user input.
2584
2585- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2586
2587- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2588
2589- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2590
2591- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2592		the application (usually a Linux kernel) when it is
2593		booted
2594
2595- CONFIG_SYS_BAUDRATE_TABLE:
2596		List of legal baudrate settings for this board.
2597
2598- CONFIG_SYS_CONSOLE_INFO_QUIET
2599		Suppress display of console information at boot.
2600
2601- CONFIG_SYS_CONSOLE_IS_IN_ENV
2602		If the board specific function
2603			extern int overwrite_console (void);
2604		returns 1, the stdin, stderr and stdout are switched to the
2605		serial port, else the settings in the environment are used.
2606
2607- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2608		Enable the call to overwrite_console().
2609
2610- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2611		Enable overwrite of previous console environment settings.
2612
2613- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2614		Begin and End addresses of the area used by the
2615		simple memory test.
2616
2617- CONFIG_SYS_ALT_MEMTEST:
2618		Enable an alternate, more extensive memory test.
2619
2620- CONFIG_SYS_MEMTEST_SCRATCH:
2621		Scratch address used by the alternate memory test
2622		You only need to set this if address zero isn't writeable
2623
2624- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2625		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2626		this specified memory area will get subtracted from the top
2627		(end) of RAM and won't get "touched" at all by U-Boot. By
2628		fixing up gd->ram_size the Linux kernel should gets passed
2629		the now "corrected" memory size and won't touch it either.
2630		This should work for arch/ppc and arch/powerpc. Only Linux
2631		board ports in arch/powerpc with bootwrapper support that
2632		recalculate the memory size from the SDRAM controller setup
2633		will have to get fixed in Linux additionally.
2634
2635		This option can be used as a workaround for the 440EPx/GRx
2636		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2637		be touched.
2638
2639		WARNING: Please make sure that this value is a multiple of
2640		the Linux page size (normally 4k). If this is not the case,
2641		then the end address of the Linux memory will be located at a
2642		non page size aligned address and this could cause major
2643		problems.
2644
2645- CONFIG_SYS_TFTP_LOADADDR:
2646		Default load address for network file downloads
2647
2648- CONFIG_SYS_LOADS_BAUD_CHANGE:
2649		Enable temporary baudrate change while serial download
2650
2651- CONFIG_SYS_SDRAM_BASE:
2652		Physical start address of SDRAM. _Must_ be 0 here.
2653
2654- CONFIG_SYS_MBIO_BASE:
2655		Physical start address of Motherboard I/O (if using a
2656		Cogent motherboard)
2657
2658- CONFIG_SYS_FLASH_BASE:
2659		Physical start address of Flash memory.
2660
2661- CONFIG_SYS_MONITOR_BASE:
2662		Physical start address of boot monitor code (set by
2663		make config files to be same as the text base address
2664		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
2665		CONFIG_SYS_FLASH_BASE when booting from flash.
2666
2667- CONFIG_SYS_MONITOR_LEN:
2668		Size of memory reserved for monitor code, used to
2669		determine _at_compile_time_ (!) if the environment is
2670		embedded within the U-Boot image, or in a separate
2671		flash sector.
2672
2673- CONFIG_SYS_MALLOC_LEN:
2674		Size of DRAM reserved for malloc() use.
2675
2676- CONFIG_SYS_BOOTM_LEN:
2677		Normally compressed uImages are limited to an
2678		uncompressed size of 8 MBytes. If this is not enough,
2679		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2680		to adjust this setting to your needs.
2681
2682- CONFIG_SYS_BOOTMAPSZ:
2683		Maximum size of memory mapped by the startup code of
2684		the Linux kernel; all data that must be processed by
2685		the Linux kernel (bd_info, boot arguments, FDT blob if
2686		used) must be put below this limit, unless "bootm_low"
2687		enviroment variable is defined and non-zero. In such case
2688		all data for the Linux kernel must be between "bootm_low"
2689		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
2690		variable "bootm_mapsize" will override the value of
2691		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
2692		then the value in "bootm_size" will be used instead.
2693
2694- CONFIG_SYS_BOOT_RAMDISK_HIGH:
2695		Enable initrd_high functionality.  If defined then the
2696		initrd_high feature is enabled and the bootm ramdisk subcommand
2697		is enabled.
2698
2699- CONFIG_SYS_BOOT_GET_CMDLINE:
2700		Enables allocating and saving kernel cmdline in space between
2701		"bootm_low" and "bootm_low" + BOOTMAPSZ.
2702
2703- CONFIG_SYS_BOOT_GET_KBD:
2704		Enables allocating and saving a kernel copy of the bd_info in
2705		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2706
2707- CONFIG_SYS_MAX_FLASH_BANKS:
2708		Max number of Flash memory banks
2709
2710- CONFIG_SYS_MAX_FLASH_SECT:
2711		Max number of sectors on a Flash chip
2712
2713- CONFIG_SYS_FLASH_ERASE_TOUT:
2714		Timeout for Flash erase operations (in ms)
2715
2716- CONFIG_SYS_FLASH_WRITE_TOUT:
2717		Timeout for Flash write operations (in ms)
2718
2719- CONFIG_SYS_FLASH_LOCK_TOUT
2720		Timeout for Flash set sector lock bit operation (in ms)
2721
2722- CONFIG_SYS_FLASH_UNLOCK_TOUT
2723		Timeout for Flash clear lock bits operation (in ms)
2724
2725- CONFIG_SYS_FLASH_PROTECTION
2726		If defined, hardware flash sectors protection is used
2727		instead of U-Boot software protection.
2728
2729- CONFIG_SYS_DIRECT_FLASH_TFTP:
2730
2731		Enable TFTP transfers directly to flash memory;
2732		without this option such a download has to be
2733		performed in two steps: (1) download to RAM, and (2)
2734		copy from RAM to flash.
2735
2736		The two-step approach is usually more reliable, since
2737		you can check if the download worked before you erase
2738		the flash, but in some situations (when system RAM is
2739		too limited to allow for a temporary copy of the
2740		downloaded image) this option may be very useful.
2741
2742- CONFIG_SYS_FLASH_CFI:
2743		Define if the flash driver uses extra elements in the
2744		common flash structure for storing flash geometry.
2745
2746- CONFIG_FLASH_CFI_DRIVER
2747		This option also enables the building of the cfi_flash driver
2748		in the drivers directory
2749
2750- CONFIG_FLASH_CFI_MTD
2751		This option enables the building of the cfi_mtd driver
2752		in the drivers directory. The driver exports CFI flash
2753		to the MTD layer.
2754
2755- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2756		Use buffered writes to flash.
2757
2758- CONFIG_FLASH_SPANSION_S29WS_N
2759		s29ws-n MirrorBit flash has non-standard addresses for buffered
2760		write commands.
2761
2762- CONFIG_SYS_FLASH_QUIET_TEST
2763		If this option is defined, the common CFI flash doesn't
2764		print it's warning upon not recognized FLASH banks. This
2765		is useful, if some of the configured banks are only
2766		optionally available.
2767
2768- CONFIG_FLASH_SHOW_PROGRESS
2769		If defined (must be an integer), print out countdown
2770		digits and dots.  Recommended value: 45 (9..1) for 80
2771		column displays, 15 (3..1) for 40 column displays.
2772
2773- CONFIG_SYS_RX_ETH_BUFFER:
2774		Defines the number of Ethernet receive buffers. On some
2775		Ethernet controllers it is recommended to set this value
2776		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2777		buffers can be full shortly after enabling the interface
2778		on high Ethernet traffic.
2779		Defaults to 4 if not defined.
2780
2781- CONFIG_ENV_MAX_ENTRIES
2782
2783	Maximum number of entries in the hash table that is used
2784	internally to store the environment settings. The default
2785	setting is supposed to be generous and should work in most
2786	cases. This setting can be used to tune behaviour; see
2787	lib/hashtable.c for details.
2788
2789The following definitions that deal with the placement and management
2790of environment data (variable area); in general, we support the
2791following configurations:
2792
2793- CONFIG_BUILD_ENVCRC:
2794
2795	Builds up envcrc with the target environment so that external utils
2796	may easily extract it and embed it in final U-Boot images.
2797
2798- CONFIG_ENV_IS_IN_FLASH:
2799
2800	Define this if the environment is in flash memory.
2801
2802	a) The environment occupies one whole flash sector, which is
2803	   "embedded" in the text segment with the U-Boot code. This
2804	   happens usually with "bottom boot sector" or "top boot
2805	   sector" type flash chips, which have several smaller
2806	   sectors at the start or the end. For instance, such a
2807	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2808	   such a case you would place the environment in one of the
2809	   4 kB sectors - with U-Boot code before and after it. With
2810	   "top boot sector" type flash chips, you would put the
2811	   environment in one of the last sectors, leaving a gap
2812	   between U-Boot and the environment.
2813
2814	- CONFIG_ENV_OFFSET:
2815
2816	   Offset of environment data (variable area) to the
2817	   beginning of flash memory; for instance, with bottom boot
2818	   type flash chips the second sector can be used: the offset
2819	   for this sector is given here.
2820
2821	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2822
2823	- CONFIG_ENV_ADDR:
2824
2825	   This is just another way to specify the start address of
2826	   the flash sector containing the environment (instead of
2827	   CONFIG_ENV_OFFSET).
2828
2829	- CONFIG_ENV_SECT_SIZE:
2830
2831	   Size of the sector containing the environment.
2832
2833
2834	b) Sometimes flash chips have few, equal sized, BIG sectors.
2835	   In such a case you don't want to spend a whole sector for
2836	   the environment.
2837
2838	- CONFIG_ENV_SIZE:
2839
2840	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2841	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2842	   of this flash sector for the environment. This saves
2843	   memory for the RAM copy of the environment.
2844
2845	   It may also save flash memory if you decide to use this
2846	   when your environment is "embedded" within U-Boot code,
2847	   since then the remainder of the flash sector could be used
2848	   for U-Boot code. It should be pointed out that this is
2849	   STRONGLY DISCOURAGED from a robustness point of view:
2850	   updating the environment in flash makes it always
2851	   necessary to erase the WHOLE sector. If something goes
2852	   wrong before the contents has been restored from a copy in
2853	   RAM, your target system will be dead.
2854
2855	- CONFIG_ENV_ADDR_REDUND
2856	  CONFIG_ENV_SIZE_REDUND
2857
2858	   These settings describe a second storage area used to hold
2859	   a redundant copy of the environment data, so that there is
2860	   a valid backup copy in case there is a power failure during
2861	   a "saveenv" operation.
2862
2863BE CAREFUL! Any changes to the flash layout, and some changes to the
2864source code will make it necessary to adapt <board>/u-boot.lds*
2865accordingly!
2866
2867
2868- CONFIG_ENV_IS_IN_NVRAM:
2869
2870	Define this if you have some non-volatile memory device
2871	(NVRAM, battery buffered SRAM) which you want to use for the
2872	environment.
2873
2874	- CONFIG_ENV_ADDR:
2875	- CONFIG_ENV_SIZE:
2876
2877	  These two #defines are used to determine the memory area you
2878	  want to use for environment. It is assumed that this memory
2879	  can just be read and written to, without any special
2880	  provision.
2881
2882BE CAREFUL! The first access to the environment happens quite early
2883in U-Boot initalization (when we try to get the setting of for the
2884console baudrate). You *MUST* have mapped your NVRAM area then, or
2885U-Boot will hang.
2886
2887Please note that even with NVRAM we still use a copy of the
2888environment in RAM: we could work on NVRAM directly, but we want to
2889keep settings there always unmodified except somebody uses "saveenv"
2890to save the current settings.
2891
2892
2893- CONFIG_ENV_IS_IN_EEPROM:
2894
2895	Use this if you have an EEPROM or similar serial access
2896	device and a driver for it.
2897
2898	- CONFIG_ENV_OFFSET:
2899	- CONFIG_ENV_SIZE:
2900
2901	  These two #defines specify the offset and size of the
2902	  environment area within the total memory of your EEPROM.
2903
2904	- CONFIG_SYS_I2C_EEPROM_ADDR:
2905	  If defined, specified the chip address of the EEPROM device.
2906	  The default address is zero.
2907
2908	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2909	  If defined, the number of bits used to address bytes in a
2910	  single page in the EEPROM device.  A 64 byte page, for example
2911	  would require six bits.
2912
2913	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2914	  If defined, the number of milliseconds to delay between
2915	  page writes.	The default is zero milliseconds.
2916
2917	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2918	  The length in bytes of the EEPROM memory array address.  Note
2919	  that this is NOT the chip address length!
2920
2921	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2922	  EEPROM chips that implement "address overflow" are ones
2923	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2924	  address and the extra bits end up in the "chip address" bit
2925	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2926	  byte chips.
2927
2928	  Note that we consider the length of the address field to
2929	  still be one byte because the extra address bits are hidden
2930	  in the chip address.
2931
2932	- CONFIG_SYS_EEPROM_SIZE:
2933	  The size in bytes of the EEPROM device.
2934
2935	- CONFIG_ENV_EEPROM_IS_ON_I2C
2936	  define this, if you have I2C and SPI activated, and your
2937	  EEPROM, which holds the environment, is on the I2C bus.
2938
2939	- CONFIG_I2C_ENV_EEPROM_BUS
2940	  if you have an Environment on an EEPROM reached over
2941	  I2C muxes, you can define here, how to reach this
2942	  EEPROM. For example:
2943
2944	  #define CONFIG_I2C_ENV_EEPROM_BUS	  "pca9547:70:d\0"
2945
2946	  EEPROM which holds the environment, is reached over
2947	  a pca9547 i2c mux with address 0x70, channel 3.
2948
2949- CONFIG_ENV_IS_IN_DATAFLASH:
2950
2951	Define this if you have a DataFlash memory device which you
2952	want to use for the environment.
2953
2954	- CONFIG_ENV_OFFSET:
2955	- CONFIG_ENV_ADDR:
2956	- CONFIG_ENV_SIZE:
2957
2958	  These three #defines specify the offset and size of the
2959	  environment area within the total memory of your DataFlash placed
2960	  at the specified address.
2961
2962- CONFIG_ENV_IS_IN_NAND:
2963
2964	Define this if you have a NAND device which you want to use
2965	for the environment.
2966
2967	- CONFIG_ENV_OFFSET:
2968	- CONFIG_ENV_SIZE:
2969
2970	  These two #defines specify the offset and size of the environment
2971	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
2972	  aligned to an erase block boundary.
2973
2974	- CONFIG_ENV_OFFSET_REDUND (optional):
2975
2976	  This setting describes a second storage area of CONFIG_ENV_SIZE
2977	  size used to hold a redundant copy of the environment data, so
2978	  that there is a valid backup copy in case there is a power failure
2979	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_RENDUND must be
2980	  aligned to an erase block boundary.
2981
2982	- CONFIG_ENV_RANGE (optional):
2983
2984	  Specifies the length of the region in which the environment
2985	  can be written.  This should be a multiple of the NAND device's
2986	  block size.  Specifying a range with more erase blocks than
2987	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
2988	  the range to be avoided.
2989
2990	- CONFIG_ENV_OFFSET_OOB (optional):
2991
2992	  Enables support for dynamically retrieving the offset of the
2993	  environment from block zero's out-of-band data.  The
2994	  "nand env.oob" command can be used to record this offset.
2995	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
2996	  using CONFIG_ENV_OFFSET_OOB.
2997
2998- CONFIG_NAND_ENV_DST
2999
3000	Defines address in RAM to which the nand_spl code should copy the
3001	environment. If redundant environment is used, it will be copied to
3002	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
3003
3004- CONFIG_SYS_SPI_INIT_OFFSET
3005
3006	Defines offset to the initial SPI buffer area in DPRAM. The
3007	area is used at an early stage (ROM part) if the environment
3008	is configured to reside in the SPI EEPROM: We need a 520 byte
3009	scratch DPRAM area. It is used between the two initialization
3010	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
3011	to be a good choice since it makes it far enough from the
3012	start of the data area as well as from the stack pointer.
3013
3014Please note that the environment is read-only until the monitor
3015has been relocated to RAM and a RAM copy of the environment has been
3016created; also, when using EEPROM you will have to use getenv_f()
3017until then to read environment variables.
3018
3019The environment is protected by a CRC32 checksum. Before the monitor
3020is relocated into RAM, as a result of a bad CRC you will be working
3021with the compiled-in default environment - *silently*!!! [This is
3022necessary, because the first environment variable we need is the
3023"baudrate" setting for the console - if we have a bad CRC, we don't
3024have any device yet where we could complain.]
3025
3026Note: once the monitor has been relocated, then it will complain if
3027the default environment is used; a new CRC is computed as soon as you
3028use the "saveenv" command to store a valid environment.
3029
3030- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
3031		Echo the inverted Ethernet link state to the fault LED.
3032
3033		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
3034		      also needs to be defined.
3035
3036- CONFIG_SYS_FAULT_MII_ADDR:
3037		MII address of the PHY to check for the Ethernet link state.
3038
3039- CONFIG_NS16550_MIN_FUNCTIONS:
3040		Define this if you desire to only have use of the NS16550_init
3041		and NS16550_putc functions for the serial driver located at
3042		drivers/serial/ns16550.c.  This option is useful for saving
3043		space for already greatly restricted images, including but not
3044		limited to NAND_SPL configurations.
3045
3046Low Level (hardware related) configuration options:
3047---------------------------------------------------
3048
3049- CONFIG_SYS_CACHELINE_SIZE:
3050		Cache Line Size of the CPU.
3051
3052- CONFIG_SYS_DEFAULT_IMMR:
3053		Default address of the IMMR after system reset.
3054
3055		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
3056		and RPXsuper) to be able to adjust the position of
3057		the IMMR register after a reset.
3058
3059- CONFIG_SYS_CCSRBAR_DEFAULT:
3060		Default (power-on reset) physical address of CCSR on Freescale
3061		PowerPC SOCs.
3062
3063- CONFIG_SYS_CCSRBAR:
3064		Virtual address of CCSR.  On a 32-bit build, this is typically
3065		the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
3066
3067		CONFIG_SYS_DEFAULT_IMMR must also be set to this value,
3068		for cross-platform code that uses that macro instead.
3069
3070- CONFIG_SYS_CCSRBAR_PHYS:
3071		Physical address of CCSR.  CCSR can be relocated to a new
3072		physical address, if desired.  In this case, this macro should
3073		be set to that address.	 Otherwise, it should be set to the
3074		same value as CONFIG_SYS_CCSRBAR_DEFAULT.  For example, CCSR
3075		is typically relocated on 36-bit builds.  It is recommended
3076		that this macro be defined via the _HIGH and _LOW macros:
3077
3078		#define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
3079			* 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
3080
3081- CONFIG_SYS_CCSRBAR_PHYS_HIGH:
3082		Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS.	This value is typically
3083		either 0 (32-bit build) or 0xF (36-bit build).	This macro is
3084		used in assembly code, so it must not contain typecasts or
3085		integer size suffixes (e.g. "ULL").
3086
3087- CONFIG_SYS_CCSRBAR_PHYS_LOW:
3088		Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS.  This macro is
3089		used in assembly code, so it must not contain typecasts or
3090		integer size suffixes (e.g. "ULL").
3091
3092- CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
3093		If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
3094		forced to a value that ensures that CCSR is not relocated.
3095
3096- Floppy Disk Support:
3097		CONFIG_SYS_FDC_DRIVE_NUMBER
3098
3099		the default drive number (default value 0)
3100
3101		CONFIG_SYS_ISA_IO_STRIDE
3102
3103		defines the spacing between FDC chipset registers
3104		(default value 1)
3105
3106		CONFIG_SYS_ISA_IO_OFFSET
3107
3108		defines the offset of register from address. It
3109		depends on which part of the data bus is connected to
3110		the FDC chipset. (default value 0)
3111
3112		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
3113		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
3114		default value.
3115
3116		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
3117		fdc_hw_init() is called at the beginning of the FDC
3118		setup. fdc_hw_init() must be provided by the board
3119		source code. It is used to make hardware dependant
3120		initializations.
3121
3122- CONFIG_IDE_AHB:
3123		Most IDE controllers were designed to be connected with PCI
3124		interface. Only few of them were designed for AHB interface.
3125		When software is doing ATA command and data transfer to
3126		IDE devices through IDE-AHB controller, some additional
3127		registers accessing to these kind of IDE-AHB controller
3128		is requierd.
3129
3130- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
3131		DO NOT CHANGE unless you know exactly what you're
3132		doing! (11-4) [MPC8xx/82xx systems only]
3133
3134- CONFIG_SYS_INIT_RAM_ADDR:
3135
3136		Start address of memory area that can be used for
3137		initial data and stack; please note that this must be
3138		writable memory that is working WITHOUT special
3139		initialization, i. e. you CANNOT use normal RAM which
3140		will become available only after programming the
3141		memory controller and running certain initialization
3142		sequences.
3143
3144		U-Boot uses the following memory types:
3145		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
3146		- MPC824X: data cache
3147		- PPC4xx:  data cache
3148
3149- CONFIG_SYS_GBL_DATA_OFFSET:
3150
3151		Offset of the initial data structure in the memory
3152		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
3153		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
3154		data is located at the end of the available space
3155		(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
3156		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
3157		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
3158		CONFIG_SYS_GBL_DATA_OFFSET) downward.
3159
3160	Note:
3161		On the MPC824X (or other systems that use the data
3162		cache for initial memory) the address chosen for
3163		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
3164		point to an otherwise UNUSED address space between
3165		the top of RAM and the start of the PCI space.
3166
3167- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
3168
3169- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
3170
3171- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
3172
3173- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
3174
3175- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
3176
3177- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
3178
3179- CONFIG_SYS_OR_TIMING_SDRAM:
3180		SDRAM timing
3181
3182- CONFIG_SYS_MAMR_PTA:
3183		periodic timer for refresh
3184
3185- CONFIG_SYS_DER:	Debug Event Register (37-47)
3186
3187- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
3188  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
3189  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
3190  CONFIG_SYS_BR1_PRELIM:
3191		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
3192
3193- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
3194  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
3195  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
3196		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
3197
3198- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
3199  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
3200		Machine Mode Register and Memory Periodic Timer
3201		Prescaler definitions (SDRAM timing)
3202
3203- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
3204		enable I2C microcode relocation patch (MPC8xx);
3205		define relocation offset in DPRAM [DSP2]
3206
3207- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
3208		enable SMC microcode relocation patch (MPC8xx);
3209		define relocation offset in DPRAM [SMC1]
3210
3211- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
3212		enable SPI microcode relocation patch (MPC8xx);
3213		define relocation offset in DPRAM [SCC4]
3214
3215- CONFIG_SYS_USE_OSCCLK:
3216		Use OSCM clock mode on MBX8xx board. Be careful,
3217		wrong setting might damage your board. Read
3218		doc/README.MBX before setting this variable!
3219
3220- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
3221		Offset of the bootmode word in DPRAM used by post
3222		(Power On Self Tests). This definition overrides
3223		#define'd default value in commproc.h resp.
3224		cpm_8260.h.
3225
3226- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
3227  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
3228  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
3229  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
3230  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
3231  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
3232  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
3233  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
3234		Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.
3235
3236- CONFIG_PCI_DISABLE_PCIE:
3237		Disable PCI-Express on systems where it is supported but not
3238		required.
3239
3240- CONFIG_SYS_SRIO:
3241		Chip has SRIO or not
3242
3243- CONFIG_SRIO1:
3244		Board has SRIO 1 port available
3245
3246- CONFIG_SRIO2:
3247		Board has SRIO 2 port available
3248
3249- CONFIG_SYS_SRIOn_MEM_VIRT:
3250		Virtual Address of SRIO port 'n' memory region
3251
3252- CONFIG_SYS_SRIOn_MEM_PHYS:
3253		Physical Address of SRIO port 'n' memory region
3254
3255- CONFIG_SYS_SRIOn_MEM_SIZE:
3256		Size of SRIO port 'n' memory region
3257
3258- CONFIG_SYS_NDFC_16
3259		Defined to tell the NDFC that the NAND chip is using a
3260		16 bit bus.
3261
3262- CONFIG_SYS_NDFC_EBC0_CFG
3263		Sets the EBC0_CFG register for the NDFC. If not defined
3264		a default value will be used.
3265
3266- CONFIG_SPD_EEPROM
3267		Get DDR timing information from an I2C EEPROM. Common
3268		with pluggable memory modules such as SODIMMs
3269
3270  SPD_EEPROM_ADDRESS
3271		I2C address of the SPD EEPROM
3272
3273- CONFIG_SYS_SPD_BUS_NUM
3274		If SPD EEPROM is on an I2C bus other than the first
3275		one, specify here. Note that the value must resolve
3276		to something your driver can deal with.
3277
3278- CONFIG_SYS_DDR_RAW_TIMING
3279		Get DDR timing information from other than SPD. Common with
3280		soldered DDR chips onboard without SPD. DDR raw timing
3281		parameters are extracted from datasheet and hard-coded into
3282		header files or board specific files.
3283
3284- CONFIG_FSL_DDR_INTERACTIVE
3285		Enable interactive DDR debugging. See doc/README.fsl-ddr.
3286
3287- CONFIG_SYS_83XX_DDR_USES_CS0
3288		Only for 83xx systems. If specified, then DDR should
3289		be configured using CS0 and CS1 instead of CS2 and CS3.
3290
3291- CONFIG_ETHER_ON_FEC[12]
3292		Define to enable FEC[12] on a 8xx series processor.
3293
3294- CONFIG_FEC[12]_PHY
3295		Define to the hardcoded PHY address which corresponds
3296		to the given FEC; i. e.
3297			#define CONFIG_FEC1_PHY 4
3298		means that the PHY with address 4 is connected to FEC1
3299
3300		When set to -1, means to probe for first available.
3301
3302- CONFIG_FEC[12]_PHY_NORXERR
3303		The PHY does not have a RXERR line (RMII only).
3304		(so program the FEC to ignore it).
3305
3306- CONFIG_RMII
3307		Enable RMII mode for all FECs.
3308		Note that this is a global option, we can't
3309		have one FEC in standard MII mode and another in RMII mode.
3310
3311- CONFIG_CRC32_VERIFY
3312		Add a verify option to the crc32 command.
3313		The syntax is:
3314
3315		=> crc32 -v <address> <count> <crc32>
3316
3317		Where address/count indicate a memory area
3318		and crc32 is the correct crc32 which the
3319		area should have.
3320
3321- CONFIG_LOOPW
3322		Add the "loopw" memory command. This only takes effect if
3323		the memory commands are activated globally (CONFIG_CMD_MEM).
3324
3325- CONFIG_MX_CYCLIC
3326		Add the "mdc" and "mwc" memory commands. These are cyclic
3327		"md/mw" commands.
3328		Examples:
3329
3330		=> mdc.b 10 4 500
3331		This command will print 4 bytes (10,11,12,13) each 500 ms.
3332
3333		=> mwc.l 100 12345678 10
3334		This command will write 12345678 to address 100 all 10 ms.
3335
3336		This only takes effect if the memory commands are activated
3337		globally (CONFIG_CMD_MEM).
3338
3339- CONFIG_SKIP_LOWLEVEL_INIT
3340		[ARM, NDS32, MIPS only] If this variable is defined, then certain
3341		low level initializations (like setting up the memory
3342		controller) are omitted and/or U-Boot does not
3343		relocate itself into RAM.
3344
3345		Normally this variable MUST NOT be defined. The only
3346		exception is when U-Boot is loaded (to RAM) by some
3347		other boot loader or by a debugger which performs
3348		these initializations itself.
3349
3350- CONFIG_SPL_BUILD
3351		Modifies the behaviour of start.S when compiling a loader
3352		that is executed before the actual U-Boot. E.g. when
3353		compiling a NAND SPL.
3354
3355- CONFIG_SYS_NAND_HW_ECC_OOBFIRST
3356		define this, if you want to read first the oob data
3357		and then the data. This is used for example on
3358		davinci plattforms.
3359
3360- CONFIG_USE_ARCH_MEMCPY
3361  CONFIG_USE_ARCH_MEMSET
3362		If these options are used a optimized version of memcpy/memset will
3363		be used if available. These functions may be faster under some
3364		conditions but may increase the binary size.
3365
3366Freescale QE/FMAN Firmware Support:
3367-----------------------------------
3368
3369The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
3370loading of "firmware", which is encoded in the QE firmware binary format.
3371This firmware often needs to be loaded during U-Boot booting, so macros
3372are used to identify the storage device (NOR flash, SPI, etc) and the address
3373within that device.
3374
3375- CONFIG_SYS_QE_FMAN_FW_ADDR
3376	The address in the storage device where the firmware is located.  The
3377	meaning of this address depends on which CONFIG_SYS_QE_FW_IN_xxx macro
3378	is also specified.
3379
3380- CONFIG_SYS_QE_FMAN_FW_LENGTH
3381	The maximum possible size of the firmware.  The firmware binary format
3382	has a field that specifies the actual size of the firmware, but it
3383	might not be possible to read any part of the firmware unless some
3384	local storage is allocated to hold the entire firmware first.
3385
3386- CONFIG_SYS_QE_FMAN_FW_IN_NOR
3387	Specifies that QE/FMAN firmware is located in NOR flash, mapped as
3388	normal addressable memory via the LBC.  CONFIG_SYS_FMAN_FW_ADDR is the
3389	virtual address in NOR flash.
3390
3391- CONFIG_SYS_QE_FMAN_FW_IN_NAND
3392	Specifies that QE/FMAN firmware is located in NAND flash.
3393	CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
3394
3395- CONFIG_SYS_QE_FMAN_FW_IN_MMC
3396	Specifies that QE/FMAN firmware is located on the primary SD/MMC
3397	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3398
3399- CONFIG_SYS_QE_FMAN_FW_IN_SPIFLASH
3400	Specifies that QE/FMAN firmware is located on the primary SPI
3401	device.  CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
3402
3403
3404Building the Software:
3405======================
3406
3407Building U-Boot has been tested in several native build environments
3408and in many different cross environments. Of course we cannot support
3409all possibly existing versions of cross development tools in all
3410(potentially obsolete) versions. In case of tool chain problems we
3411recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
3412which is extensively used to build and test U-Boot.
3413
3414If you are not using a native environment, it is assumed that you
3415have GNU cross compiling tools available in your path. In this case,
3416you must set the environment variable CROSS_COMPILE in your shell.
3417Note that no changes to the Makefile or any other source files are
3418necessary. For example using the ELDK on a 4xx CPU, please enter:
3419
3420	$ CROSS_COMPILE=ppc_4xx-
3421	$ export CROSS_COMPILE
3422
3423Note: If you wish to generate Windows versions of the utilities in
3424      the tools directory you can use the MinGW toolchain
3425      (http://www.mingw.org).  Set your HOST tools to the MinGW
3426      toolchain and execute 'make tools'.  For example:
3427
3428       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools
3429
3430      Binaries such as tools/mkimage.exe will be created which can
3431      be executed on computers running Windows.
3432
3433U-Boot is intended to be simple to build. After installing the
3434sources you must configure U-Boot for one specific board type. This
3435is done by typing:
3436
3437	make NAME_config
3438
3439where "NAME_config" is the name of one of the existing configu-
3440rations; see the main Makefile for supported names.
3441
3442Note: for some board special configuration names may exist; check if
3443      additional information is available from the board vendor; for
3444      instance, the TQM823L systems are available without (standard)
3445      or with LCD support. You can select such additional "features"
3446      when choosing the configuration, i. e.
3447
3448      make TQM823L_config
3449	- will configure for a plain TQM823L, i. e. no LCD support
3450
3451      make TQM823L_LCD_config
3452	- will configure for a TQM823L with U-Boot console on LCD
3453
3454      etc.
3455
3456
3457Finally, type "make all", and you should get some working U-Boot
3458images ready for download to / installation on your system:
3459
3460- "u-boot.bin" is a raw binary image
3461- "u-boot" is an image in ELF binary format
3462- "u-boot.srec" is in Motorola S-Record format
3463
3464By default the build is performed locally and the objects are saved
3465in the source directory. One of the two methods can be used to change
3466this behavior and build U-Boot to some external directory:
3467
34681. Add O= to the make command line invocations:
3469
3470	make O=/tmp/build distclean
3471	make O=/tmp/build NAME_config
3472	make O=/tmp/build all
3473
34742. Set environment variable BUILD_DIR to point to the desired location:
3475
3476	export BUILD_DIR=/tmp/build
3477	make distclean
3478	make NAME_config
3479	make all
3480
3481Note that the command line "O=" setting overrides the BUILD_DIR environment
3482variable.
3483
3484
3485Please be aware that the Makefiles assume you are using GNU make, so
3486for instance on NetBSD you might need to use "gmake" instead of
3487native "make".
3488
3489
3490If the system board that you have is not listed, then you will need
3491to port U-Boot to your hardware platform. To do this, follow these
3492steps:
3493
34941.  Add a new configuration option for your board to the toplevel
3495    "Makefile" and to the "MAKEALL" script, using the existing
3496    entries as examples. Note that here and at many other places
3497    boards and other names are listed in alphabetical sort order. Please
3498    keep this order.
34992.  Create a new directory to hold your board specific code. Add any
3500    files you need. In your board directory, you will need at least
3501    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
35023.  Create a new configuration file "include/configs/<board>.h" for
3503    your board
35043.  If you're porting U-Boot to a new CPU, then also create a new
3505    directory to hold your CPU specific code. Add any files you need.
35064.  Run "make <board>_config" with your new name.
35075.  Type "make", and you should get a working "u-boot.srec" file
3508    to be installed on your target system.
35096.  Debug and solve any problems that might arise.
3510    [Of course, this last step is much harder than it sounds.]
3511
3512
3513Testing of U-Boot Modifications, Ports to New Hardware, etc.:
3514==============================================================
3515
3516If you have modified U-Boot sources (for instance added a new board
3517or support for new devices, a new CPU, etc.) you are expected to
3518provide feedback to the other developers. The feedback normally takes
3519the form of a "patch", i. e. a context diff against a certain (latest
3520official or latest in the git repository) version of U-Boot sources.
3521
3522But before you submit such a patch, please verify that your modifi-
3523cation did not break existing code. At least make sure that *ALL* of
3524the supported boards compile WITHOUT ANY compiler warnings. To do so,
3525just run the "MAKEALL" script, which will configure and build U-Boot
3526for ALL supported system. Be warned, this will take a while. You can
3527select which (cross) compiler to use by passing a `CROSS_COMPILE'
3528environment variable to the script, i. e. to use the ELDK cross tools
3529you can type
3530
3531	CROSS_COMPILE=ppc_8xx- MAKEALL
3532
3533or to build on a native PowerPC system you can type
3534
3535	CROSS_COMPILE=' ' MAKEALL
3536
3537When using the MAKEALL script, the default behaviour is to build
3538U-Boot in the source directory. This location can be changed by
3539setting the BUILD_DIR environment variable. Also, for each target
3540built, the MAKEALL script saves two log files (<target>.ERR and
3541<target>.MAKEALL) in the <source dir>/LOG directory. This default
3542location can be changed by setting the MAKEALL_LOGDIR environment
3543variable. For example:
3544
3545	export BUILD_DIR=/tmp/build
3546	export MAKEALL_LOGDIR=/tmp/log
3547	CROSS_COMPILE=ppc_8xx- MAKEALL
3548
3549With the above settings build objects are saved in the /tmp/build,
3550log files are saved in the /tmp/log and the source tree remains clean
3551during the whole build process.
3552
3553
3554See also "U-Boot Porting Guide" below.
3555
3556
3557Monitor Commands - Overview:
3558============================
3559
3560go	- start application at address 'addr'
3561run	- run commands in an environment variable
3562bootm	- boot application image from memory
3563bootp	- boot image via network using BootP/TFTP protocol
3564tftpboot- boot image via network using TFTP protocol
3565	       and env variables "ipaddr" and "serverip"
3566	       (and eventually "gatewayip")
3567tftpput - upload a file via network using TFTP protocol
3568rarpboot- boot image via network using RARP/TFTP protocol
3569diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
3570loads	- load S-Record file over serial line
3571loadb	- load binary file over serial line (kermit mode)
3572md	- memory display
3573mm	- memory modify (auto-incrementing)
3574nm	- memory modify (constant address)
3575mw	- memory write (fill)
3576cp	- memory copy
3577cmp	- memory compare
3578crc32	- checksum calculation
3579i2c	- I2C sub-system
3580sspi	- SPI utility commands
3581base	- print or set address offset
3582printenv- print environment variables
3583setenv	- set environment variables
3584saveenv - save environment variables to persistent storage
3585protect - enable or disable FLASH write protection
3586erase	- erase FLASH memory
3587flinfo	- print FLASH memory information
3588bdinfo	- print Board Info structure
3589iminfo	- print header information for application image
3590coninfo - print console devices and informations
3591ide	- IDE sub-system
3592loop	- infinite loop on address range
3593loopw	- infinite write loop on address range
3594mtest	- simple RAM test
3595icache	- enable or disable instruction cache
3596dcache	- enable or disable data cache
3597reset	- Perform RESET of the CPU
3598echo	- echo args to console
3599version - print monitor version
3600help	- print online help
3601?	- alias for 'help'
3602
3603
3604Monitor Commands - Detailed Description:
3605========================================
3606
3607TODO.
3608
3609For now: just type "help <command>".
3610
3611
3612Environment Variables:
3613======================
3614
3615U-Boot supports user configuration using Environment Variables which
3616can be made persistent by saving to Flash memory.
3617
3618Environment Variables are set using "setenv", printed using
3619"printenv", and saved to Flash using "saveenv". Using "setenv"
3620without a value can be used to delete a variable from the
3621environment. As long as you don't save the environment you are
3622working with an in-memory copy. In case the Flash area containing the
3623environment is erased by accident, a default environment is provided.
3624
3625Some configuration options can be set using Environment Variables.
3626
3627List of environment variables (most likely not complete):
3628
3629  baudrate	- see CONFIG_BAUDRATE
3630
3631  bootdelay	- see CONFIG_BOOTDELAY
3632
3633  bootcmd	- see CONFIG_BOOTCOMMAND
3634
3635  bootargs	- Boot arguments when booting an RTOS image
3636
3637  bootfile	- Name of the image to load with TFTP
3638
3639  bootm_low	- Memory range available for image processing in the bootm
3640		  command can be restricted. This variable is given as
3641		  a hexadecimal number and defines lowest address allowed
3642		  for use by the bootm command. See also "bootm_size"
3643		  environment variable. Address defined by "bootm_low" is
3644		  also the base of the initial memory mapping for the Linux
3645		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
3646		  bootm_mapsize.
3647
3648  bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
3649		  This variable is given as a hexadecimal number and it
3650		  defines the size of the memory region starting at base
3651		  address bootm_low that is accessible by the Linux kernel
3652		  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
3653		  as the default value if it is defined, and bootm_size is
3654		  used otherwise.
3655
3656  bootm_size	- Memory range available for image processing in the bootm
3657		  command can be restricted. This variable is given as
3658		  a hexadecimal number and defines the size of the region
3659		  allowed for use by the bootm command. See also "bootm_low"
3660		  environment variable.
3661
3662  updatefile	- Location of the software update file on a TFTP server, used
3663		  by the automatic software update feature. Please refer to
3664		  documentation in doc/README.update for more details.
3665
3666  autoload	- if set to "no" (any string beginning with 'n'),
3667		  "bootp" will just load perform a lookup of the
3668		  configuration from the BOOTP server, but not try to
3669		  load any image using TFTP
3670
3671  autostart	- if set to "yes", an image loaded using the "bootp",
3672		  "rarpboot", "tftpboot" or "diskboot" commands will
3673		  be automatically started (by internally calling
3674		  "bootm")
3675
3676		  If set to "no", a standalone image passed to the
3677		  "bootm" command will be copied to the load address
3678		  (and eventually uncompressed), but NOT be started.
3679		  This can be used to load and uncompress arbitrary
3680		  data.
3681
3682  fdt_high	- if set this restricts the maximum address that the
3683		  flattened device tree will be copied into upon boot.
3684		  For example, if you have a system with 1 GB memory
3685		  at physical address 0x10000000, while Linux kernel
3686		  only recognizes the first 704 MB as low memory, you
3687		  may need to set fdt_high as 0x3C000000 to have the
3688		  device tree blob be copied to the maximum address
3689		  of the 704 MB low memory, so that Linux kernel can
3690		  access it during the boot procedure.
3691
3692		  If this is set to the special value 0xFFFFFFFF then
3693		  the fdt will not be copied at all on boot.  For this
3694		  to work it must reside in writable memory, have
3695		  sufficient padding on the end of it for u-boot to
3696		  add the information it needs into it, and the memory
3697		  must be accessible by the kernel.
3698
3699  fdtcontroladdr- if set this is the address of the control flattened
3700		  device tree used by U-Boot when CONFIG_OF_CONTROL is
3701		  defined.
3702
3703  i2cfast	- (PPC405GP|PPC405EP only)
3704		  if set to 'y' configures Linux I2C driver for fast
3705		  mode (400kHZ). This environment variable is used in
3706		  initialization code. So, for changes to be effective
3707		  it must be saved and board must be reset.
3708
3709  initrd_high	- restrict positioning of initrd images:
3710		  If this variable is not set, initrd images will be
3711		  copied to the highest possible address in RAM; this
3712		  is usually what you want since it allows for
3713		  maximum initrd size. If for some reason you want to
3714		  make sure that the initrd image is loaded below the
3715		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
3716		  variable to a value of "no" or "off" or "0".
3717		  Alternatively, you can set it to a maximum upper
3718		  address to use (U-Boot will still check that it
3719		  does not overwrite the U-Boot stack and data).
3720
3721		  For instance, when you have a system with 16 MB
3722		  RAM, and want to reserve 4 MB from use by Linux,
3723		  you can do this by adding "mem=12M" to the value of
3724		  the "bootargs" variable. However, now you must make
3725		  sure that the initrd image is placed in the first
3726		  12 MB as well - this can be done with
3727
3728		  setenv initrd_high 00c00000
3729
3730		  If you set initrd_high to 0xFFFFFFFF, this is an
3731		  indication to U-Boot that all addresses are legal
3732		  for the Linux kernel, including addresses in flash
3733		  memory. In this case U-Boot will NOT COPY the
3734		  ramdisk at all. This may be useful to reduce the
3735		  boot time on your system, but requires that this
3736		  feature is supported by your Linux kernel.
3737
3738  ipaddr	- IP address; needed for tftpboot command
3739
3740  loadaddr	- Default load address for commands like "bootp",
3741		  "rarpboot", "tftpboot", "loadb" or "diskboot"
3742
3743  loads_echo	- see CONFIG_LOADS_ECHO
3744
3745  serverip	- TFTP server IP address; needed for tftpboot command
3746
3747  bootretry	- see CONFIG_BOOT_RETRY_TIME
3748
3749  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
3750
3751  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
3752
3753  ethprime	- controls which interface is used first.
3754
3755  ethact	- controls which interface is currently active.
3756		  For example you can do the following
3757
3758		  => setenv ethact FEC
3759		  => ping 192.168.0.1 # traffic sent on FEC
3760		  => setenv ethact SCC
3761		  => ping 10.0.0.1 # traffic sent on SCC
3762
3763  ethrotate	- When set to "no" U-Boot does not go through all
3764		  available network interfaces.
3765		  It just stays at the currently selected interface.
3766
3767  netretry	- When set to "no" each network operation will
3768		  either succeed or fail without retrying.
3769		  When set to "once" the network operation will
3770		  fail when all the available network interfaces
3771		  are tried once without success.
3772		  Useful on scripts which control the retry operation
3773		  themselves.
3774
3775  npe_ucode	- set load address for the NPE microcode
3776
3777  tftpsrcport	- If this is set, the value is used for TFTP's
3778		  UDP source port.
3779
3780  tftpdstport	- If this is set, the value is used for TFTP's UDP
3781		  destination port instead of the Well Know Port 69.
3782
3783  tftpblocksize - Block size to use for TFTP transfers; if not set,
3784		  we use the TFTP server's default block size
3785
3786  tftptimeout	- Retransmission timeout for TFTP packets (in milli-
3787		  seconds, minimum value is 1000 = 1 second). Defines
3788		  when a packet is considered to be lost so it has to
3789		  be retransmitted. The default is 5000 = 5 seconds.
3790		  Lowering this value may make downloads succeed
3791		  faster in networks with high packet loss rates or
3792		  with unreliable TFTP servers.
3793
3794  vlan		- When set to a value < 4095 the traffic over
3795		  Ethernet is encapsulated/received over 802.1q
3796		  VLAN tagged frames.
3797
3798The following image location variables contain the location of images
3799used in booting. The "Image" column gives the role of the image and is
3800not an environment variable name. The other columns are environment
3801variable names. "File Name" gives the name of the file on a TFTP
3802server, "RAM Address" gives the location in RAM the image will be
3803loaded to, and "Flash Location" gives the image's address in NOR
3804flash or offset in NAND flash.
3805
3806*Note* - these variables don't have to be defined for all boards, some
3807boards currenlty use other variables for these purposes, and some
3808boards use these variables for other purposes.
3809
3810Image		    File Name	     RAM Address       Flash Location
3811-----		    ---------	     -----------       --------------
3812u-boot		    u-boot	     u-boot_addr_r     u-boot_addr
3813Linux kernel	    bootfile	     kernel_addr_r     kernel_addr
3814device tree blob    fdtfile	     fdt_addr_r	       fdt_addr
3815ramdisk		    ramdiskfile	     ramdisk_addr_r    ramdisk_addr
3816
3817The following environment variables may be used and automatically
3818updated by the network boot commands ("bootp" and "rarpboot"),
3819depending the information provided by your boot server:
3820
3821  bootfile	- see above
3822  dnsip		- IP address of your Domain Name Server
3823  dnsip2	- IP address of your secondary Domain Name Server
3824  gatewayip	- IP address of the Gateway (Router) to use
3825  hostname	- Target hostname
3826  ipaddr	- see above
3827  netmask	- Subnet Mask
3828  rootpath	- Pathname of the root filesystem on the NFS server
3829  serverip	- see above
3830
3831
3832There are two special Environment Variables:
3833
3834  serial#	- contains hardware identification information such
3835		  as type string and/or serial number
3836  ethaddr	- Ethernet address
3837
3838These variables can be set only once (usually during manufacturing of
3839the board). U-Boot refuses to delete or overwrite these variables
3840once they have been set once.
3841
3842
3843Further special Environment Variables:
3844
3845  ver		- Contains the U-Boot version string as printed
3846		  with the "version" command. This variable is
3847		  readonly (see CONFIG_VERSION_VARIABLE).
3848
3849
3850Please note that changes to some configuration parameters may take
3851only effect after the next boot (yes, that's just like Windoze :-).
3852
3853
3854Command Line Parsing:
3855=====================
3856
3857There are two different command line parsers available with U-Boot:
3858the old "simple" one, and the much more powerful "hush" shell:
3859
3860Old, simple command line parser:
3861--------------------------------
3862
3863- supports environment variables (through setenv / saveenv commands)
3864- several commands on one line, separated by ';'
3865- variable substitution using "... ${name} ..." syntax
3866- special characters ('$', ';') can be escaped by prefixing with '\',
3867  for example:
3868	setenv bootcmd bootm \${address}
3869- You can also escape text by enclosing in single apostrophes, for example:
3870	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3871
3872Hush shell:
3873-----------
3874
3875- similar to Bourne shell, with control structures like
3876  if...then...else...fi, for...do...done; while...do...done,
3877  until...do...done, ...
3878- supports environment ("global") variables (through setenv / saveenv
3879  commands) and local shell variables (through standard shell syntax
3880  "name=value"); only environment variables can be used with "run"
3881  command
3882
3883General rules:
3884--------------
3885
3886(1) If a command line (or an environment variable executed by a "run"
3887    command) contains several commands separated by semicolon, and
3888    one of these commands fails, then the remaining commands will be
3889    executed anyway.
3890
3891(2) If you execute several variables with one call to run (i. e.
3892    calling run with a list of variables as arguments), any failing
3893    command will cause "run" to terminate, i. e. the remaining
3894    variables are not executed.
3895
3896Note for Redundant Ethernet Interfaces:
3897=======================================
3898
3899Some boards come with redundant Ethernet interfaces; U-Boot supports
3900such configurations and is capable of automatic selection of a
3901"working" interface when needed. MAC assignment works as follows:
3902
3903Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3904MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3905"eth1addr" (=>eth1), "eth2addr", ...
3906
3907If the network interface stores some valid MAC address (for instance
3908in SROM), this is used as default address if there is NO correspon-
3909ding setting in the environment; if the corresponding environment
3910variable is set, this overrides the settings in the card; that means:
3911
3912o If the SROM has a valid MAC address, and there is no address in the
3913  environment, the SROM's address is used.
3914
3915o If there is no valid address in the SROM, and a definition in the
3916  environment exists, then the value from the environment variable is
3917  used.
3918
3919o If both the SROM and the environment contain a MAC address, and
3920  both addresses are the same, this MAC address is used.
3921
3922o If both the SROM and the environment contain a MAC address, and the
3923  addresses differ, the value from the environment is used and a
3924  warning is printed.
3925
3926o If neither SROM nor the environment contain a MAC address, an error
3927  is raised.
3928
3929If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
3930will be programmed into hardware as part of the initialization process.	 This
3931may be skipped by setting the appropriate 'ethmacskip' environment variable.
3932The naming convention is as follows:
3933"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
3934
3935Image Formats:
3936==============
3937
3938U-Boot is capable of booting (and performing other auxiliary operations on)
3939images in two formats:
3940
3941New uImage format (FIT)
3942-----------------------
3943
3944Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3945to Flattened Device Tree). It allows the use of images with multiple
3946components (several kernels, ramdisks, etc.), with contents protected by
3947SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3948
3949
3950Old uImage format
3951-----------------
3952
3953Old image format is based on binary files which can be basically anything,
3954preceded by a special header; see the definitions in include/image.h for
3955details; basically, the header defines the following image properties:
3956
3957* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3958  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3959  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3960  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3961  INTEGRITY).
3962* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3963  IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3964  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
3965* Compression Type (uncompressed, gzip, bzip2)
3966* Load Address
3967* Entry Point
3968* Image Name
3969* Image Timestamp
3970
3971The header is marked by a special Magic Number, and both the header
3972and the data portions of the image are secured against corruption by
3973CRC32 checksums.
3974
3975
3976Linux Support:
3977==============
3978
3979Although U-Boot should support any OS or standalone application
3980easily, the main focus has always been on Linux during the design of
3981U-Boot.
3982
3983U-Boot includes many features that so far have been part of some
3984special "boot loader" code within the Linux kernel. Also, any
3985"initrd" images to be used are no longer part of one big Linux image;
3986instead, kernel and "initrd" are separate images. This implementation
3987serves several purposes:
3988
3989- the same features can be used for other OS or standalone
3990  applications (for instance: using compressed images to reduce the
3991  Flash memory footprint)
3992
3993- it becomes much easier to port new Linux kernel versions because
3994  lots of low-level, hardware dependent stuff are done by U-Boot
3995
3996- the same Linux kernel image can now be used with different "initrd"
3997  images; of course this also means that different kernel images can
3998  be run with the same "initrd". This makes testing easier (you don't
3999  have to build a new "zImage.initrd" Linux image when you just
4000  change a file in your "initrd"). Also, a field-upgrade of the
4001  software is easier now.
4002
4003
4004Linux HOWTO:
4005============
4006
4007Porting Linux to U-Boot based systems:
4008---------------------------------------
4009
4010U-Boot cannot save you from doing all the necessary modifications to
4011configure the Linux device drivers for use with your target hardware
4012(no, we don't intend to provide a full virtual machine interface to
4013Linux :-).
4014
4015But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
4016
4017Just make sure your machine specific header file (for instance
4018include/asm-ppc/tqm8xx.h) includes the same definition of the Board
4019Information structure as we define in include/asm-<arch>/u-boot.h,
4020and make sure that your definition of IMAP_ADDR uses the same value
4021as your U-Boot configuration in CONFIG_SYS_IMMR.
4022
4023
4024Configuring the Linux kernel:
4025-----------------------------
4026
4027No specific requirements for U-Boot. Make sure you have some root
4028device (initial ramdisk, NFS) for your target system.
4029
4030
4031Building a Linux Image:
4032-----------------------
4033
4034With U-Boot, "normal" build targets like "zImage" or "bzImage" are
4035not used. If you use recent kernel source, a new build target
4036"uImage" will exist which automatically builds an image usable by
4037U-Boot. Most older kernels also have support for a "pImage" target,
4038which was introduced for our predecessor project PPCBoot and uses a
4039100% compatible format.
4040
4041Example:
4042
4043	make TQM850L_config
4044	make oldconfig
4045	make dep
4046	make uImage
4047
4048The "uImage" build target uses a special tool (in 'tools/mkimage') to
4049encapsulate a compressed Linux kernel image with header	 information,
4050CRC32 checksum etc. for use with U-Boot. This is what we are doing:
4051
4052* build a standard "vmlinux" kernel image (in ELF binary format):
4053
4054* convert the kernel into a raw binary image:
4055
4056	${CROSS_COMPILE}-objcopy -O binary \
4057				 -R .note -R .comment \
4058				 -S vmlinux linux.bin
4059
4060* compress the binary image:
4061
4062	gzip -9 linux.bin
4063
4064* package compressed binary image for U-Boot:
4065
4066	mkimage -A ppc -O linux -T kernel -C gzip \
4067		-a 0 -e 0 -n "Linux Kernel Image" \
4068		-d linux.bin.gz uImage
4069
4070
4071The "mkimage" tool can also be used to create ramdisk images for use
4072with U-Boot, either separated from the Linux kernel image, or
4073combined into one file. "mkimage" encapsulates the images with a 64
4074byte header containing information about target architecture,
4075operating system, image type, compression method, entry points, time
4076stamp, CRC32 checksums, etc.
4077
4078"mkimage" can be called in two ways: to verify existing images and
4079print the header information, or to build new images.
4080
4081In the first form (with "-l" option) mkimage lists the information
4082contained in the header of an existing U-Boot image; this includes
4083checksum verification:
4084
4085	tools/mkimage -l image
4086	  -l ==> list image header information
4087
4088The second form (with "-d" option) is used to build a U-Boot image
4089from a "data file" which is used as image payload:
4090
4091	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
4092		      -n name -d data_file image
4093	  -A ==> set architecture to 'arch'
4094	  -O ==> set operating system to 'os'
4095	  -T ==> set image type to 'type'
4096	  -C ==> set compression type 'comp'
4097	  -a ==> set load address to 'addr' (hex)
4098	  -e ==> set entry point to 'ep' (hex)
4099	  -n ==> set image name to 'name'
4100	  -d ==> use image data from 'datafile'
4101
4102Right now, all Linux kernels for PowerPC systems use the same load
4103address (0x00000000), but the entry point address depends on the
4104kernel version:
4105
4106- 2.2.x kernels have the entry point at 0x0000000C,
4107- 2.3.x and later kernels have the entry point at 0x00000000.
4108
4109So a typical call to build a U-Boot image would read:
4110
4111	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4112	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
4113	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
4114	> examples/uImage.TQM850L
4115	Image Name:   2.4.4 kernel for TQM850L
4116	Created:      Wed Jul 19 02:34:59 2000
4117	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4118	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4119	Load Address: 0x00000000
4120	Entry Point:  0x00000000
4121
4122To verify the contents of the image (or check for corruption):
4123
4124	-> tools/mkimage -l examples/uImage.TQM850L
4125	Image Name:   2.4.4 kernel for TQM850L
4126	Created:      Wed Jul 19 02:34:59 2000
4127	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
4128	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
4129	Load Address: 0x00000000
4130	Entry Point:  0x00000000
4131
4132NOTE: for embedded systems where boot time is critical you can trade
4133speed for memory and install an UNCOMPRESSED image instead: this
4134needs more space in Flash, but boots much faster since it does not
4135need to be uncompressed:
4136
4137	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
4138	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
4139	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
4140	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
4141	> examples/uImage.TQM850L-uncompressed
4142	Image Name:   2.4.4 kernel for TQM850L
4143	Created:      Wed Jul 19 02:34:59 2000
4144	Image Type:   PowerPC Linux Kernel Image (uncompressed)
4145	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
4146	Load Address: 0x00000000
4147	Entry Point:  0x00000000
4148
4149
4150Similar you can build U-Boot images from a 'ramdisk.image.gz' file
4151when your kernel is intended to use an initial ramdisk:
4152
4153	-> tools/mkimage -n 'Simple Ramdisk Image' \
4154	> -A ppc -O linux -T ramdisk -C gzip \
4155	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
4156	Image Name:   Simple Ramdisk Image
4157	Created:      Wed Jan 12 14:01:50 2000
4158	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
4159	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
4160	Load Address: 0x00000000
4161	Entry Point:  0x00000000
4162
4163
4164Installing a Linux Image:
4165-------------------------
4166
4167To downloading a U-Boot image over the serial (console) interface,
4168you must convert the image to S-Record format:
4169
4170	objcopy -I binary -O srec examples/image examples/image.srec
4171
4172The 'objcopy' does not understand the information in the U-Boot
4173image header, so the resulting S-Record file will be relative to
4174address 0x00000000. To load it to a given address, you need to
4175specify the target address as 'offset' parameter with the 'loads'
4176command.
4177
4178Example: install the image to address 0x40100000 (which on the
4179TQM8xxL is in the first Flash bank):
4180
4181	=> erase 40100000 401FFFFF
4182
4183	.......... done
4184	Erased 8 sectors
4185
4186	=> loads 40100000
4187	## Ready for S-Record download ...
4188	~>examples/image.srec
4189	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
4190	...
4191	15989 15990 15991 15992
4192	[file transfer complete]
4193	[connected]
4194	## Start Addr = 0x00000000
4195
4196
4197You can check the success of the download using the 'iminfo' command;
4198this includes a checksum verification so you can be sure no data
4199corruption happened:
4200
4201	=> imi 40100000
4202
4203	## Checking Image at 40100000 ...
4204	   Image Name:	 2.2.13 for initrd on TQM850L
4205	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4206	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4207	   Load Address: 00000000
4208	   Entry Point:	 0000000c
4209	   Verifying Checksum ... OK
4210
4211
4212Boot Linux:
4213-----------
4214
4215The "bootm" command is used to boot an application that is stored in
4216memory (RAM or Flash). In case of a Linux kernel image, the contents
4217of the "bootargs" environment variable is passed to the kernel as
4218parameters. You can check and modify this variable using the
4219"printenv" and "setenv" commands:
4220
4221
4222	=> printenv bootargs
4223	bootargs=root=/dev/ram
4224
4225	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4226
4227	=> printenv bootargs
4228	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4229
4230	=> bootm 40020000
4231	## Booting Linux kernel at 40020000 ...
4232	   Image Name:	 2.2.13 for NFS on TQM850L
4233	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4234	   Data Size:	 381681 Bytes = 372 kB = 0 MB
4235	   Load Address: 00000000
4236	   Entry Point:	 0000000c
4237	   Verifying Checksum ... OK
4238	   Uncompressing Kernel Image ... OK
4239	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
4240	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
4241	time_init: decrementer frequency = 187500000/60
4242	Calibrating delay loop... 49.77 BogoMIPS
4243	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
4244	...
4245
4246If you want to boot a Linux kernel with initial RAM disk, you pass
4247the memory addresses of both the kernel and the initrd image (PPBCOOT
4248format!) to the "bootm" command:
4249
4250	=> imi 40100000 40200000
4251
4252	## Checking Image at 40100000 ...
4253	   Image Name:	 2.2.13 for initrd on TQM850L
4254	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4255	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4256	   Load Address: 00000000
4257	   Entry Point:	 0000000c
4258	   Verifying Checksum ... OK
4259
4260	## Checking Image at 40200000 ...
4261	   Image Name:	 Simple Ramdisk Image
4262	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4263	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4264	   Load Address: 00000000
4265	   Entry Point:	 00000000
4266	   Verifying Checksum ... OK
4267
4268	=> bootm 40100000 40200000
4269	## Booting Linux kernel at 40100000 ...
4270	   Image Name:	 2.2.13 for initrd on TQM850L
4271	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4272	   Data Size:	 335725 Bytes = 327 kB = 0 MB
4273	   Load Address: 00000000
4274	   Entry Point:	 0000000c
4275	   Verifying Checksum ... OK
4276	   Uncompressing Kernel Image ... OK
4277	## Loading RAMDisk Image at 40200000 ...
4278	   Image Name:	 Simple Ramdisk Image
4279	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
4280	   Data Size:	 566530 Bytes = 553 kB = 0 MB
4281	   Load Address: 00000000
4282	   Entry Point:	 00000000
4283	   Verifying Checksum ... OK
4284	   Loading Ramdisk ... OK
4285	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
4286	Boot arguments: root=/dev/ram
4287	time_init: decrementer frequency = 187500000/60
4288	Calibrating delay loop... 49.77 BogoMIPS
4289	...
4290	RAMDISK: Compressed image found at block 0
4291	VFS: Mounted root (ext2 filesystem).
4292
4293	bash#
4294
4295Boot Linux and pass a flat device tree:
4296-----------
4297
4298First, U-Boot must be compiled with the appropriate defines. See the section
4299titled "Linux Kernel Interface" above for a more in depth explanation. The
4300following is an example of how to start a kernel and pass an updated
4301flat device tree:
4302
4303=> print oftaddr
4304oftaddr=0x300000
4305=> print oft
4306oft=oftrees/mpc8540ads.dtb
4307=> tftp $oftaddr $oft
4308Speed: 1000, full duplex
4309Using TSEC0 device
4310TFTP from server 192.168.1.1; our IP address is 192.168.1.101
4311Filename 'oftrees/mpc8540ads.dtb'.
4312Load address: 0x300000
4313Loading: #
4314done
4315Bytes transferred = 4106 (100a hex)
4316=> tftp $loadaddr $bootfile
4317Speed: 1000, full duplex
4318Using TSEC0 device
4319TFTP from server 192.168.1.1; our IP address is 192.168.1.2
4320Filename 'uImage'.
4321Load address: 0x200000
4322Loading:############
4323done
4324Bytes transferred = 1029407 (fb51f hex)
4325=> print loadaddr
4326loadaddr=200000
4327=> print oftaddr
4328oftaddr=0x300000
4329=> bootm $loadaddr - $oftaddr
4330## Booting image at 00200000 ...
4331   Image Name:	 Linux-2.6.17-dirty
4332   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
4333   Data Size:	 1029343 Bytes = 1005.2 kB
4334   Load Address: 00000000
4335   Entry Point:	 00000000
4336   Verifying Checksum ... OK
4337   Uncompressing Kernel Image ... OK
4338Booting using flat device tree at 0x300000
4339Using MPC85xx ADS machine description
4340Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
4341[snip]
4342
4343
4344More About U-Boot Image Types:
4345------------------------------
4346
4347U-Boot supports the following image types:
4348
4349   "Standalone Programs" are directly runnable in the environment
4350	provided by U-Boot; it is expected that (if they behave
4351	well) you can continue to work in U-Boot after return from
4352	the Standalone Program.
4353   "OS Kernel Images" are usually images of some Embedded OS which
4354	will take over control completely. Usually these programs
4355	will install their own set of exception handlers, device
4356	drivers, set up the MMU, etc. - this means, that you cannot
4357	expect to re-enter U-Boot except by resetting the CPU.
4358   "RAMDisk Images" are more or less just data blocks, and their
4359	parameters (address, size) are passed to an OS kernel that is
4360	being started.
4361   "Multi-File Images" contain several images, typically an OS
4362	(Linux) kernel image and one or more data images like
4363	RAMDisks. This construct is useful for instance when you want
4364	to boot over the network using BOOTP etc., where the boot
4365	server provides just a single image file, but you want to get
4366	for instance an OS kernel and a RAMDisk image.
4367
4368	"Multi-File Images" start with a list of image sizes, each
4369	image size (in bytes) specified by an "uint32_t" in network
4370	byte order. This list is terminated by an "(uint32_t)0".
4371	Immediately after the terminating 0 follow the images, one by
4372	one, all aligned on "uint32_t" boundaries (size rounded up to
4373	a multiple of 4 bytes).
4374
4375   "Firmware Images" are binary images containing firmware (like
4376	U-Boot or FPGA images) which usually will be programmed to
4377	flash memory.
4378
4379   "Script files" are command sequences that will be executed by
4380	U-Boot's command interpreter; this feature is especially
4381	useful when you configure U-Boot to use a real shell (hush)
4382	as command interpreter.
4383
4384
4385Standalone HOWTO:
4386=================
4387
4388One of the features of U-Boot is that you can dynamically load and
4389run "standalone" applications, which can use some resources of
4390U-Boot like console I/O functions or interrupt services.
4391
4392Two simple examples are included with the sources:
4393
4394"Hello World" Demo:
4395-------------------
4396
4397'examples/hello_world.c' contains a small "Hello World" Demo
4398application; it is automatically compiled when you build U-Boot.
4399It's configured to run at address 0x00040004, so you can play with it
4400like that:
4401
4402	=> loads
4403	## Ready for S-Record download ...
4404	~>examples/hello_world.srec
4405	1 2 3 4 5 6 7 8 9 10 11 ...
4406	[file transfer complete]
4407	[connected]
4408	## Start Addr = 0x00040004
4409
4410	=> go 40004 Hello World! This is a test.
4411	## Starting application at 0x00040004 ...
4412	Hello World
4413	argc = 7
4414	argv[0] = "40004"
4415	argv[1] = "Hello"
4416	argv[2] = "World!"
4417	argv[3] = "This"
4418	argv[4] = "is"
4419	argv[5] = "a"
4420	argv[6] = "test."
4421	argv[7] = "<NULL>"
4422	Hit any key to exit ...
4423
4424	## Application terminated, rc = 0x0
4425
4426Another example, which demonstrates how to register a CPM interrupt
4427handler with the U-Boot code, can be found in 'examples/timer.c'.
4428Here, a CPM timer is set up to generate an interrupt every second.
4429The interrupt service routine is trivial, just printing a '.'
4430character, but this is just a demo program. The application can be
4431controlled by the following keys:
4432
4433	? - print current values og the CPM Timer registers
4434	b - enable interrupts and start timer
4435	e - stop timer and disable interrupts
4436	q - quit application
4437
4438	=> loads
4439	## Ready for S-Record download ...
4440	~>examples/timer.srec
4441	1 2 3 4 5 6 7 8 9 10 11 ...
4442	[file transfer complete]
4443	[connected]
4444	## Start Addr = 0x00040004
4445
4446	=> go 40004
4447	## Starting application at 0x00040004 ...
4448	TIMERS=0xfff00980
4449	Using timer 1
4450	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
4451
4452Hit 'b':
4453	[q, b, e, ?] Set interval 1000000 us
4454	Enabling timer
4455Hit '?':
4456	[q, b, e, ?] ........
4457	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
4458Hit '?':
4459	[q, b, e, ?] .
4460	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
4461Hit '?':
4462	[q, b, e, ?] .
4463	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
4464Hit '?':
4465	[q, b, e, ?] .
4466	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
4467Hit 'e':
4468	[q, b, e, ?] ...Stopping timer
4469Hit 'q':
4470	[q, b, e, ?] ## Application terminated, rc = 0x0
4471
4472
4473Minicom warning:
4474================
4475
4476Over time, many people have reported problems when trying to use the
4477"minicom" terminal emulation program for serial download. I (wd)
4478consider minicom to be broken, and recommend not to use it. Under
4479Unix, I recommend to use C-Kermit for general purpose use (and
4480especially for kermit binary protocol download ("loadb" command), and
4481use "cu" for S-Record download ("loads" command).
4482
4483Nevertheless, if you absolutely want to use it try adding this
4484configuration to your "File transfer protocols" section:
4485
4486	   Name	   Program			Name U/D FullScr IO-Red. Multi
4487	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
4488	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
4489
4490
4491NetBSD Notes:
4492=============
4493
4494Starting at version 0.9.2, U-Boot supports NetBSD both as host
4495(build U-Boot) and target system (boots NetBSD/mpc8xx).
4496
4497Building requires a cross environment; it is known to work on
4498NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
4499need gmake since the Makefiles are not compatible with BSD make).
4500Note that the cross-powerpc package does not install include files;
4501attempting to build U-Boot will fail because <machine/ansi.h> is
4502missing.  This file has to be installed and patched manually:
4503
4504	# cd /usr/pkg/cross/powerpc-netbsd/include
4505	# mkdir powerpc
4506	# ln -s powerpc machine
4507	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
4508	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
4509
4510Native builds *don't* work due to incompatibilities between native
4511and U-Boot include files.
4512
4513Booting assumes that (the first part of) the image booted is a
4514stage-2 loader which in turn loads and then invokes the kernel
4515proper. Loader sources will eventually appear in the NetBSD source
4516tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
4517meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
4518
4519
4520Implementation Internals:
4521=========================
4522
4523The following is not intended to be a complete description of every
4524implementation detail. However, it should help to understand the
4525inner workings of U-Boot and make it easier to port it to custom
4526hardware.
4527
4528
4529Initial Stack, Global Data:
4530---------------------------
4531
4532The implementation of U-Boot is complicated by the fact that U-Boot
4533starts running out of ROM (flash memory), usually without access to
4534system RAM (because the memory controller is not initialized yet).
4535This means that we don't have writable Data or BSS segments, and BSS
4536is not initialized as zero. To be able to get a C environment working
4537at all, we have to allocate at least a minimal stack. Implementation
4538options for this are defined and restricted by the CPU used: Some CPU
4539models provide on-chip memory (like the IMMR area on MPC8xx and
4540MPC826x processors), on others (parts of) the data cache can be
4541locked as (mis-) used as memory, etc.
4542
4543	Chris Hallinan posted a good summary of these issues to the
4544	U-Boot mailing list:
4545
4546	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
4547	From: "Chris Hallinan" <clh@net1plus.com>
4548	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
4549	...
4550
4551	Correct me if I'm wrong, folks, but the way I understand it
4552	is this: Using DCACHE as initial RAM for Stack, etc, does not
4553	require any physical RAM backing up the cache. The cleverness
4554	is that the cache is being used as a temporary supply of
4555	necessary storage before the SDRAM controller is setup. It's
4556	beyond the scope of this list to explain the details, but you
4557	can see how this works by studying the cache architecture and
4558	operation in the architecture and processor-specific manuals.
4559
4560	OCM is On Chip Memory, which I believe the 405GP has 4K. It
4561	is another option for the system designer to use as an
4562	initial stack/RAM area prior to SDRAM being available. Either
4563	option should work for you. Using CS 4 should be fine if your
4564	board designers haven't used it for something that would
4565	cause you grief during the initial boot! It is frequently not
4566	used.
4567
4568	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
4569	with your processor/board/system design. The default value
4570	you will find in any recent u-boot distribution in
4571	walnut.h should work for you. I'd set it to a value larger
4572	than your SDRAM module. If you have a 64MB SDRAM module, set
4573	it above 400_0000. Just make sure your board has no resources
4574	that are supposed to respond to that address! That code in
4575	start.S has been around a while and should work as is when
4576	you get the config right.
4577
4578	-Chris Hallinan
4579	DS4.COM, Inc.
4580
4581It is essential to remember this, since it has some impact on the C
4582code for the initialization procedures:
4583
4584* Initialized global data (data segment) is read-only. Do not attempt
4585  to write it.
4586
4587* Do not use any uninitialized global data (or implicitely initialized
4588  as zero data - BSS segment) at all - this is undefined, initiali-
4589  zation is performed later (when relocating to RAM).
4590
4591* Stack space is very limited. Avoid big data buffers or things like
4592  that.
4593
4594Having only the stack as writable memory limits means we cannot use
4595normal global data to share information beween the code. But it
4596turned out that the implementation of U-Boot can be greatly
4597simplified by making a global data structure (gd_t) available to all
4598functions. We could pass a pointer to this data as argument to _all_
4599functions, but this would bloat the code. Instead we use a feature of
4600the GCC compiler (Global Register Variables) to share the data: we
4601place a pointer (gd) to the global data into a register which we
4602reserve for this purpose.
4603
4604When choosing a register for such a purpose we are restricted by the
4605relevant  (E)ABI  specifications for the current architecture, and by
4606GCC's implementation.
4607
4608For PowerPC, the following registers have specific use:
4609	R1:	stack pointer
4610	R2:	reserved for system use
4611	R3-R4:	parameter passing and return values
4612	R5-R10: parameter passing
4613	R13:	small data area pointer
4614	R30:	GOT pointer
4615	R31:	frame pointer
4616
4617	(U-Boot also uses R12 as internal GOT pointer. r12
4618	is a volatile register so r12 needs to be reset when
4619	going back and forth between asm and C)
4620
4621    ==> U-Boot will use R2 to hold a pointer to the global data
4622
4623    Note: on PPC, we could use a static initializer (since the
4624    address of the global data structure is known at compile time),
4625    but it turned out that reserving a register results in somewhat
4626    smaller code - although the code savings are not that big (on
4627    average for all boards 752 bytes for the whole U-Boot image,
4628    624 text + 127 data).
4629
4630On Blackfin, the normal C ABI (except for P3) is followed as documented here:
4631	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
4632
4633    ==> U-Boot will use P3 to hold a pointer to the global data
4634
4635On ARM, the following registers are used:
4636
4637	R0:	function argument word/integer result
4638	R1-R3:	function argument word
4639	R9:	GOT pointer
4640	R10:	stack limit (used only if stack checking if enabled)
4641	R11:	argument (frame) pointer
4642	R12:	temporary workspace
4643	R13:	stack pointer
4644	R14:	link register
4645	R15:	program counter
4646
4647    ==> U-Boot will use R8 to hold a pointer to the global data
4648
4649On Nios II, the ABI is documented here:
4650	http://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
4651
4652    ==> U-Boot will use gp to hold a pointer to the global data
4653
4654    Note: on Nios II, we give "-G0" option to gcc and don't use gp
4655    to access small data sections, so gp is free.
4656
4657On NDS32, the following registers are used:
4658
4659	R0-R1:	argument/return
4660	R2-R5:	argument
4661	R15:	temporary register for assembler
4662	R16:	trampoline register
4663	R28:	frame pointer (FP)
4664	R29:	global pointer (GP)
4665	R30:	link register (LP)
4666	R31:	stack pointer (SP)
4667	PC:	program counter (PC)
4668
4669    ==> U-Boot will use R10 to hold a pointer to the global data
4670
4671NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
4672or current versions of GCC may "optimize" the code too much.
4673
4674Memory Management:
4675------------------
4676
4677U-Boot runs in system state and uses physical addresses, i.e. the
4678MMU is not used either for address mapping nor for memory protection.
4679
4680The available memory is mapped to fixed addresses using the memory
4681controller. In this process, a contiguous block is formed for each
4682memory type (Flash, SDRAM, SRAM), even when it consists of several
4683physical memory banks.
4684
4685U-Boot is installed in the first 128 kB of the first Flash bank (on
4686TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
4687booting and sizing and initializing DRAM, the code relocates itself
4688to the upper end of DRAM. Immediately below the U-Boot code some
4689memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
4690configuration setting]. Below that, a structure with global Board
4691Info data is placed, followed by the stack (growing downward).
4692
4693Additionally, some exception handler code is copied to the low 8 kB
4694of DRAM (0x00000000 ... 0x00001FFF).
4695
4696So a typical memory configuration with 16 MB of DRAM could look like
4697this:
4698
4699	0x0000 0000	Exception Vector code
4700	      :
4701	0x0000 1FFF
4702	0x0000 2000	Free for Application Use
4703	      :
4704	      :
4705
4706	      :
4707	      :
4708	0x00FB FF20	Monitor Stack (Growing downward)
4709	0x00FB FFAC	Board Info Data and permanent copy of global data
4710	0x00FC 0000	Malloc Arena
4711	      :
4712	0x00FD FFFF
4713	0x00FE 0000	RAM Copy of Monitor Code
4714	...		eventually: LCD or video framebuffer
4715	...		eventually: pRAM (Protected RAM - unchanged by reset)
4716	0x00FF FFFF	[End of RAM]
4717
4718
4719System Initialization:
4720----------------------
4721
4722In the reset configuration, U-Boot starts at the reset entry point
4723(on most PowerPC systems at address 0x00000100). Because of the reset
4724configuration for CS0# this is a mirror of the onboard Flash memory.
4725To be able to re-map memory U-Boot then jumps to its link address.
4726To be able to implement the initialization code in C, a (small!)
4727initial stack is set up in the internal Dual Ported RAM (in case CPUs
4728which provide such a feature like MPC8xx or MPC8260), or in a locked
4729part of the data cache. After that, U-Boot initializes the CPU core,
4730the caches and the SIU.
4731
4732Next, all (potentially) available memory banks are mapped using a
4733preliminary mapping. For example, we put them on 512 MB boundaries
4734(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
4735on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
4736programmed for SDRAM access. Using the temporary configuration, a
4737simple memory test is run that determines the size of the SDRAM
4738banks.
4739
4740When there is more than one SDRAM bank, and the banks are of
4741different size, the largest is mapped first. For equal size, the first
4742bank (CS2#) is mapped first. The first mapping is always for address
47430x00000000, with any additional banks following immediately to create
4744contiguous memory starting from 0.
4745
4746Then, the monitor installs itself at the upper end of the SDRAM area
4747and allocates memory for use by malloc() and for the global Board
4748Info data; also, the exception vector code is copied to the low RAM
4749pages, and the final stack is set up.
4750
4751Only after this relocation will you have a "normal" C environment;
4752until that you are restricted in several ways, mostly because you are
4753running from ROM, and because the code will have to be relocated to a
4754new address in RAM.
4755
4756
4757U-Boot Porting Guide:
4758----------------------
4759
4760[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
4761list, October 2002]
4762
4763
4764int main(int argc, char *argv[])
4765{
4766	sighandler_t no_more_time;
4767
4768	signal(SIGALRM, no_more_time);
4769	alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
4770
4771	if (available_money > available_manpower) {
4772		Pay consultant to port U-Boot;
4773		return 0;
4774	}
4775
4776	Download latest U-Boot source;
4777
4778	Subscribe to u-boot mailing list;
4779
4780	if (clueless)
4781		email("Hi, I am new to U-Boot, how do I get started?");
4782
4783	while (learning) {
4784		Read the README file in the top level directory;
4785		Read http://www.denx.de/twiki/bin/view/DULG/Manual;
4786		Read applicable doc/*.README;
4787		Read the source, Luke;
4788		/* find . -name "*.[chS]" | xargs grep -i <keyword> */
4789	}
4790
4791	if (available_money > toLocalCurrency ($2500))
4792		Buy a BDI3000;
4793	else
4794		Add a lot of aggravation and time;
4795
4796	if (a similar board exists) {	/* hopefully... */
4797		cp -a board/<similar> board/<myboard>
4798		cp include/configs/<similar>.h include/configs/<myboard>.h
4799	} else {
4800		Create your own board support subdirectory;
4801		Create your own board include/configs/<myboard>.h file;
4802	}
4803	Edit new board/<myboard> files
4804	Edit new include/configs/<myboard>.h
4805
4806	while (!accepted) {
4807		while (!running) {
4808			do {
4809				Add / modify source code;
4810			} until (compiles);
4811			Debug;
4812			if (clueless)
4813				email("Hi, I am having problems...");
4814		}
4815		Send patch file to the U-Boot email list;
4816		if (reasonable critiques)
4817			Incorporate improvements from email list code review;
4818		else
4819			Defend code as written;
4820	}
4821
4822	return 0;
4823}
4824
4825void no_more_time (int sig)
4826{
4827      hire_a_guru();
4828}
4829
4830
4831Coding Standards:
4832-----------------
4833
4834All contributions to U-Boot should conform to the Linux kernel
4835coding style; see the file "Documentation/CodingStyle" and the script
4836"scripts/Lindent" in your Linux kernel source directory.
4837
4838Source files originating from a different project (for example the
4839MTD subsystem) are generally exempt from these guidelines and are not
4840reformated to ease subsequent migration to newer versions of those
4841sources.
4842
4843Please note that U-Boot is implemented in C (and to some small parts in
4844Assembler); no C++ is used, so please do not use C++ style comments (//)
4845in your code.
4846
4847Please also stick to the following formatting rules:
4848- remove any trailing white space
4849- use TAB characters for indentation and vertical alignment, not spaces
4850- make sure NOT to use DOS '\r\n' line feeds
4851- do not add more than 2 consecutive empty lines to source files
4852- do not add trailing empty lines to source files
4853
4854Submissions which do not conform to the standards may be returned
4855with a request to reformat the changes.
4856
4857
4858Submitting Patches:
4859-------------------
4860
4861Since the number of patches for U-Boot is growing, we need to
4862establish some rules. Submissions which do not conform to these rules
4863may be rejected, even when they contain important and valuable stuff.
4864
4865Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4866
4867Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
4868see http://lists.denx.de/mailman/listinfo/u-boot
4869
4870When you send a patch, please include the following information with
4871it:
4872
4873* For bug fixes: a description of the bug and how your patch fixes
4874  this bug. Please try to include a way of demonstrating that the
4875  patch actually fixes something.
4876
4877* For new features: a description of the feature and your
4878  implementation.
4879
4880* A CHANGELOG entry as plaintext (separate from the patch)
4881
4882* For major contributions, your entry to the CREDITS file
4883
4884* When you add support for a new board, don't forget to add this
4885  board to the MAINTAINERS file, too.
4886
4887* If your patch adds new configuration options, don't forget to
4888  document these in the README file.
4889
4890* The patch itself. If you are using git (which is *strongly*
4891  recommended) you can easily generate the patch using the
4892  "git format-patch". If you then use "git send-email" to send it to
4893  the U-Boot mailing list, you will avoid most of the common problems
4894  with some other mail clients.
4895
4896  If you cannot use git, use "diff -purN OLD NEW". If your version of
4897  diff does not support these options, then get the latest version of
4898  GNU diff.
4899
4900  The current directory when running this command shall be the parent
4901  directory of the U-Boot source tree (i. e. please make sure that
4902  your patch includes sufficient directory information for the
4903  affected files).
4904
4905  We prefer patches as plain text. MIME attachments are discouraged,
4906  and compressed attachments must not be used.
4907
4908* If one logical set of modifications affects or creates several
4909  files, all these changes shall be submitted in a SINGLE patch file.
4910
4911* Changesets that contain different, unrelated modifications shall be
4912  submitted as SEPARATE patches, one patch per changeset.
4913
4914
4915Notes:
4916
4917* Before sending the patch, run the MAKEALL script on your patched
4918  source tree and make sure that no errors or warnings are reported
4919  for any of the boards.
4920
4921* Keep your modifications to the necessary minimum: A patch
4922  containing several unrelated changes or arbitrary reformats will be
4923  returned with a request to re-formatting / split it.
4924
4925* If you modify existing code, make sure that your new code does not
4926  add to the memory footprint of the code ;-) Small is beautiful!
4927  When adding new features, these should compile conditionally only
4928  (using #ifdef), and the resulting code with the new feature
4929  disabled must not need more memory than the old code without your
4930  modification.
4931
4932* Remember that there is a size limit of 100 kB per message on the
4933  u-boot mailing list. Bigger patches will be moderated. If they are
4934  reasonable and not too big, they will be acknowledged. But patches
4935  bigger than the size limit should be avoided.
4936