xref: /rk3399_rockchip-uboot/README (revision d4f70da544c33db3e4fce6473dea4ecca4322545)
1#
2# (C) Copyright 2000 - 2008
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
129U-Boot uses a 3 level version number containing a version, a
130sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
131sub-version "34", and patchlevel "4".
132
133The patchlevel is used to indicate certain stages of development
134between released versions, i. e. officially released versions of
135U-Boot will always have a patchlevel of "0".
136
137
138Directory Hierarchy:
139====================
140
141- board		Board dependent files
142- common	Misc architecture independent functions
143- cpu		CPU specific files
144  - 74xx_7xx	Files specific to Freescale MPC74xx and 7xx CPUs
145  - arm720t	Files specific to ARM 720 CPUs
146  - arm920t	Files specific to ARM 920 CPUs
147    - at91rm9200 Files specific to Atmel AT91RM9200 CPU
148    - imx	Files specific to Freescale MC9328 i.MX CPUs
149    - s3c24x0	Files specific to Samsung S3C24X0 CPUs
150  - arm925t	Files specific to ARM 925 CPUs
151  - arm926ejs	Files specific to ARM 926 CPUs
152  - arm1136	Files specific to ARM 1136 CPUs
153  - at32ap	Files specific to Atmel AVR32 AP CPUs
154  - blackfin	Files specific to Analog Devices Blackfin CPUs
155  - i386	Files specific to i386 CPUs
156  - ixp		Files specific to Intel XScale IXP CPUs
157  - leon2	Files specific to Gaisler LEON2 SPARC CPU
158  - leon3	Files specific to Gaisler LEON3 SPARC CPU
159  - mcf52x2	Files specific to Freescale ColdFire MCF52x2 CPUs
160  - mcf5227x	Files specific to Freescale ColdFire MCF5227x CPUs
161  - mcf532x	Files specific to Freescale ColdFire MCF5329 CPUs
162  - mcf5445x	Files specific to Freescale ColdFire MCF5445x CPUs
163  - mcf547x_8x	Files specific to Freescale ColdFire MCF547x_8x CPUs
164  - mips	Files specific to MIPS CPUs
165  - mpc5xx	Files specific to Freescale MPC5xx  CPUs
166  - mpc5xxx	Files specific to Freescale MPC5xxx CPUs
167  - mpc8xx	Files specific to Freescale MPC8xx  CPUs
168  - mpc8220	Files specific to Freescale MPC8220 CPUs
169  - mpc824x	Files specific to Freescale MPC824x CPUs
170  - mpc8260	Files specific to Freescale MPC8260 CPUs
171  - mpc85xx	Files specific to Freescale MPC85xx CPUs
172  - nios	Files specific to Altera NIOS CPUs
173  - nios2	Files specific to Altera Nios-II CPUs
174  - ppc4xx	Files specific to AMCC PowerPC 4xx CPUs
175  - pxa		Files specific to Intel XScale PXA CPUs
176  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
177  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
178- disk		Code for disk drive partition handling
179- doc		Documentation (don't expect too much)
180- drivers	Commonly used device drivers
181- dtt		Digital Thermometer and Thermostat drivers
182- examples	Example code for standalone applications, etc.
183- include	Header Files
184- lib_arm	Files generic to ARM	 architecture
185- lib_avr32	Files generic to AVR32	 architecture
186- lib_blackfin	Files generic to Blackfin architecture
187- lib_generic	Files generic to all	 architectures
188- lib_i386	Files generic to i386	 architecture
189- lib_m68k	Files generic to m68k	 architecture
190- lib_mips	Files generic to MIPS	 architecture
191- lib_nios	Files generic to NIOS	 architecture
192- lib_ppc	Files generic to PowerPC architecture
193- lib_sparc	Files generic to SPARC	 architecture
194- libfdt	Library files to support flattened device trees
195- net		Networking code
196- post		Power On Self Test
197- rtc		Real Time Clock drivers
198- tools		Tools to build S-Record or U-Boot images, etc.
199
200Software Configuration:
201=======================
202
203Configuration is usually done using C preprocessor defines; the
204rationale behind that is to avoid dead code whenever possible.
205
206There are two classes of configuration variables:
207
208* Configuration _OPTIONS_:
209  These are selectable by the user and have names beginning with
210  "CONFIG_".
211
212* Configuration _SETTINGS_:
213  These depend on the hardware etc. and should not be meddled with if
214  you don't know what you're doing; they have names beginning with
215  "CONFIG_SYS_".
216
217Later we will add a configuration tool - probably similar to or even
218identical to what's used for the Linux kernel. Right now, we have to
219do the configuration by hand, which means creating some symbolic
220links and editing some configuration files. We use the TQM8xxL boards
221as an example here.
222
223
224Selection of Processor Architecture and Board Type:
225---------------------------------------------------
226
227For all supported boards there are ready-to-use default
228configurations available; just type "make <board_name>_config".
229
230Example: For a TQM823L module type:
231
232	cd u-boot
233	make TQM823L_config
234
235For the Cogent platform, you need to specify the CPU type as well;
236e.g. "make cogent_mpc8xx_config". And also configure the cogent
237directory according to the instructions in cogent/README.
238
239
240Configuration Options:
241----------------------
242
243Configuration depends on the combination of board and CPU type; all
244such information is kept in a configuration file
245"include/configs/<board_name>.h".
246
247Example: For a TQM823L module, all configuration settings are in
248"include/configs/TQM823L.h".
249
250
251Many of the options are named exactly as the corresponding Linux
252kernel configuration options. The intention is to make it easier to
253build a config tool - later.
254
255
256The following options need to be configured:
257
258- CPU Type:	Define exactly one, e.g. CONFIG_MPC85XX.
259
260- Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
261
262- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
263		Define exactly one, e.g. CONFIG_ATSTK1002
264
265- CPU Module Type: (if CONFIG_COGENT is defined)
266		Define exactly one of
267		CONFIG_CMA286_60_OLD
268--- FIXME --- not tested yet:
269		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
270		CONFIG_CMA287_23, CONFIG_CMA287_50
271
272- Motherboard Type: (if CONFIG_COGENT is defined)
273		Define exactly one of
274		CONFIG_CMA101, CONFIG_CMA102
275
276- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
277		Define one or more of
278		CONFIG_CMA302
279
280- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
281		Define one or more of
282		CONFIG_LCD_HEARTBEAT	- update a character position on
283					  the LCD display every second with
284					  a "rotator" |\-/|\-/
285
286- Board flavour: (if CONFIG_MPC8260ADS is defined)
287		CONFIG_ADSTYPE
288		Possible values are:
289			CONFIG_SYS_8260ADS	- original MPC8260ADS
290			CONFIG_SYS_8266ADS	- MPC8266ADS
291			CONFIG_SYS_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
292			CONFIG_SYS_8272ADS	- MPC8272ADS
293
294- MPC824X Family Member (if CONFIG_MPC824X is defined)
295		Define exactly one of
296		CONFIG_MPC8240, CONFIG_MPC8245
297
298- 8xx CPU Options: (if using an MPC8xx CPU)
299		CONFIG_8xx_GCLK_FREQ	- deprecated: CPU clock if
300					  get_gclk_freq() cannot work
301					  e.g. if there is no 32KHz
302					  reference PIT/RTC clock
303		CONFIG_8xx_OSCLK	- PLL input clock (either EXTCLK
304					  or XTAL/EXTAL)
305
306- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
307		CONFIG_SYS_8xx_CPUCLK_MIN
308		CONFIG_SYS_8xx_CPUCLK_MAX
309		CONFIG_8xx_CPUCLK_DEFAULT
310			See doc/README.MPC866
311
312		CONFIG_SYS_MEASURE_CPUCLK
313
314		Define this to measure the actual CPU clock instead
315		of relying on the correctness of the configured
316		values. Mostly useful for board bringup to make sure
317		the PLL is locked at the intended frequency. Note
318		that this requires a (stable) reference clock (32 kHz
319		RTC clock or CONFIG_SYS_8XX_XIN)
320
321- Intel Monahans options:
322		CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
323
324		Defines the Monahans run mode to oscillator
325		ratio. Valid values are 8, 16, 24, 31. The core
326		frequency is this value multiplied by 13 MHz.
327
328		CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
329
330		Defines the Monahans turbo mode to oscillator
331		ratio. Valid values are 1 (default if undefined) and
332		2. The core frequency as calculated above is multiplied
333		by this value.
334
335- Linux Kernel Interface:
336		CONFIG_CLOCKS_IN_MHZ
337
338		U-Boot stores all clock information in Hz
339		internally. For binary compatibility with older Linux
340		kernels (which expect the clocks passed in the
341		bd_info data to be in MHz) the environment variable
342		"clocks_in_mhz" can be defined so that U-Boot
343		converts clock data to MHZ before passing it to the
344		Linux kernel.
345		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
346		"clocks_in_mhz=1" is automatically included in the
347		default environment.
348
349		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
350
351		When transferring memsize parameter to linux, some versions
352		expect it to be in bytes, others in MB.
353		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
354
355		CONFIG_OF_LIBFDT
356
357		New kernel versions are expecting firmware settings to be
358		passed using flattened device trees (based on open firmware
359		concepts).
360
361		CONFIG_OF_LIBFDT
362		 * New libfdt-based support
363		 * Adds the "fdt" command
364		 * The bootm command automatically updates the fdt
365
366		OF_CPU - The proper name of the cpus node.
367		OF_SOC - The proper name of the soc node.
368		OF_TBCLK - The timebase frequency.
369		OF_STDOUT_PATH - The path to the console device
370
371		boards with QUICC Engines require OF_QE to set UCC MAC
372		addresses
373
374		CONFIG_OF_BOARD_SETUP
375
376		Board code has addition modification that it wants to make
377		to the flat device tree before handing it off to the kernel
378
379		CONFIG_OF_BOOT_CPU
380
381		This define fills in the correct boot CPU in the boot
382		param header, the default value is zero if undefined.
383
384- vxWorks boot parameters:
385
386		bootvx constructs a valid bootline using the following
387		environments variables: bootfile, ipaddr, serverip, hostname.
388		It loads the vxWorks image pointed bootfile.
389
390		CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name
391		CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address
392		CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server
393		CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters
394
395		CONFIG_SYS_VXWORKS_ADD_PARAMS
396
397		Add it at the end of the bootline. E.g "u=username pw=secret"
398
399		Note: If a "bootargs" environment is defined, it will overwride
400		the defaults discussed just above.
401
402- Serial Ports:
403		CONFIG_PL010_SERIAL
404
405		Define this if you want support for Amba PrimeCell PL010 UARTs.
406
407		CONFIG_PL011_SERIAL
408
409		Define this if you want support for Amba PrimeCell PL011 UARTs.
410
411		CONFIG_PL011_CLOCK
412
413		If you have Amba PrimeCell PL011 UARTs, set this variable to
414		the clock speed of the UARTs.
415
416		CONFIG_PL01x_PORTS
417
418		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
419		define this to a list of base addresses for each (supported)
420		port. See e.g. include/configs/versatile.h
421
422
423- Console Interface:
424		Depending on board, define exactly one serial port
425		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
426		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
427		console by defining CONFIG_8xx_CONS_NONE
428
429		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
430		port routines must be defined elsewhere
431		(i.e. serial_init(), serial_getc(), ...)
432
433		CONFIG_CFB_CONSOLE
434		Enables console device for a color framebuffer. Needs following
435		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
436			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
437						(default big endian)
438			VIDEO_HW_RECTFILL	graphic chip supports
439						rectangle fill
440						(cf. smiLynxEM)
441			VIDEO_HW_BITBLT		graphic chip supports
442						bit-blit (cf. smiLynxEM)
443			VIDEO_VISIBLE_COLS	visible pixel columns
444						(cols=pitch)
445			VIDEO_VISIBLE_ROWS	visible pixel rows
446			VIDEO_PIXEL_SIZE	bytes per pixel
447			VIDEO_DATA_FORMAT	graphic data format
448						(0-5, cf. cfb_console.c)
449			VIDEO_FB_ADRS		framebuffer address
450			VIDEO_KBD_INIT_FCT	keyboard int fct
451						(i.e. i8042_kbd_init())
452			VIDEO_TSTC_FCT		test char fct
453						(i.e. i8042_tstc)
454			VIDEO_GETC_FCT		get char fct
455						(i.e. i8042_getc)
456			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
457						(requires blink timer
458						cf. i8042.c)
459			CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
460			CONFIG_CONSOLE_TIME	display time/date info in
461						upper right corner
462						(requires CONFIG_CMD_DATE)
463			CONFIG_VIDEO_LOGO	display Linux logo in
464						upper left corner
465			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
466						linux_logo.h for logo.
467						Requires CONFIG_VIDEO_LOGO
468			CONFIG_CONSOLE_EXTRA_INFO
469						additional board info beside
470						the logo
471
472		When CONFIG_CFB_CONSOLE is defined, video console is
473		default i/o. Serial console can be forced with
474		environment 'console=serial'.
475
476		When CONFIG_SILENT_CONSOLE is defined, all console
477		messages (by U-Boot and Linux!) can be silenced with
478		the "silent" environment variable. See
479		doc/README.silent for more information.
480
481- Console Baudrate:
482		CONFIG_BAUDRATE - in bps
483		Select one of the baudrates listed in
484		CONFIG_SYS_BAUDRATE_TABLE, see below.
485		CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
486
487- Interrupt driven serial port input:
488		CONFIG_SERIAL_SOFTWARE_FIFO
489
490		PPC405GP only.
491		Use an interrupt handler for receiving data on the
492		serial port. It also enables using hardware handshake
493		(RTS/CTS) and UART's built-in FIFO. Set the number of
494		bytes the interrupt driven input buffer should have.
495
496		Leave undefined to disable this feature, including
497		disable the buffer and hardware handshake.
498
499- Console UART Number:
500		CONFIG_UART1_CONSOLE
501
502		AMCC PPC4xx only.
503		If defined internal UART1 (and not UART0) is used
504		as default U-Boot console.
505
506- Boot Delay:	CONFIG_BOOTDELAY - in seconds
507		Delay before automatically booting the default image;
508		set to -1 to disable autoboot.
509
510		See doc/README.autoboot for these options that
511		work with CONFIG_BOOTDELAY. None are required.
512		CONFIG_BOOT_RETRY_TIME
513		CONFIG_BOOT_RETRY_MIN
514		CONFIG_AUTOBOOT_KEYED
515		CONFIG_AUTOBOOT_PROMPT
516		CONFIG_AUTOBOOT_DELAY_STR
517		CONFIG_AUTOBOOT_STOP_STR
518		CONFIG_AUTOBOOT_DELAY_STR2
519		CONFIG_AUTOBOOT_STOP_STR2
520		CONFIG_ZERO_BOOTDELAY_CHECK
521		CONFIG_RESET_TO_RETRY
522
523- Autoboot Command:
524		CONFIG_BOOTCOMMAND
525		Only needed when CONFIG_BOOTDELAY is enabled;
526		define a command string that is automatically executed
527		when no character is read on the console interface
528		within "Boot Delay" after reset.
529
530		CONFIG_BOOTARGS
531		This can be used to pass arguments to the bootm
532		command. The value of CONFIG_BOOTARGS goes into the
533		environment value "bootargs".
534
535		CONFIG_RAMBOOT and CONFIG_NFSBOOT
536		The value of these goes into the environment as
537		"ramboot" and "nfsboot" respectively, and can be used
538		as a convenience, when switching between booting from
539		RAM and NFS.
540
541- Pre-Boot Commands:
542		CONFIG_PREBOOT
543
544		When this option is #defined, the existence of the
545		environment variable "preboot" will be checked
546		immediately before starting the CONFIG_BOOTDELAY
547		countdown and/or running the auto-boot command resp.
548		entering interactive mode.
549
550		This feature is especially useful when "preboot" is
551		automatically generated or modified. For an example
552		see the LWMON board specific code: here "preboot" is
553		modified when the user holds down a certain
554		combination of keys on the (special) keyboard when
555		booting the systems
556
557- Serial Download Echo Mode:
558		CONFIG_LOADS_ECHO
559		If defined to 1, all characters received during a
560		serial download (using the "loads" command) are
561		echoed back. This might be needed by some terminal
562		emulations (like "cu"), but may as well just take
563		time on others. This setting #define's the initial
564		value of the "loads_echo" environment variable.
565
566- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
567		CONFIG_KGDB_BAUDRATE
568		Select one of the baudrates listed in
569		CONFIG_SYS_BAUDRATE_TABLE, see below.
570
571- Monitor Functions:
572		Monitor commands can be included or excluded
573		from the build by using the #include files
574		"config_cmd_all.h" and #undef'ing unwanted
575		commands, or using "config_cmd_default.h"
576		and augmenting with additional #define's
577		for wanted commands.
578
579		The default command configuration includes all commands
580		except those marked below with a "*".
581
582		CONFIG_CMD_ASKENV	* ask for env variable
583		CONFIG_CMD_AUTOSCRIPT	  Autoscript Support
584		CONFIG_CMD_BDI		  bdinfo
585		CONFIG_CMD_BEDBUG	* Include BedBug Debugger
586		CONFIG_CMD_BMP		* BMP support
587		CONFIG_CMD_BSP		* Board specific commands
588		CONFIG_CMD_BOOTD	  bootd
589		CONFIG_CMD_CACHE	* icache, dcache
590		CONFIG_CMD_CONSOLE	  coninfo
591		CONFIG_CMD_DATE		* support for RTC, date/time...
592		CONFIG_CMD_DHCP		* DHCP support
593		CONFIG_CMD_DIAG		* Diagnostics
594		CONFIG_CMD_DOC		* Disk-On-Chip Support
595		CONFIG_CMD_DTT		* Digital Therm and Thermostat
596		CONFIG_CMD_ECHO		  echo arguments
597		CONFIG_CMD_EEPROM	* EEPROM read/write support
598		CONFIG_CMD_ELF		* bootelf, bootvx
599		CONFIG_CMD_ENV		  saveenv
600		CONFIG_CMD_FDC		* Floppy Disk Support
601		CONFIG_CMD_FAT		* FAT partition support
602		CONFIG_CMD_FDOS		* Dos diskette Support
603		CONFIG_CMD_FLASH	  flinfo, erase, protect
604		CONFIG_CMD_FPGA		  FPGA device initialization support
605		CONFIG_CMD_HWFLOW	* RTS/CTS hw flow control
606		CONFIG_CMD_I2C		* I2C serial bus support
607		CONFIG_CMD_IDE		* IDE harddisk support
608		CONFIG_CMD_IMI		  iminfo
609		CONFIG_CMD_IMLS		  List all found images
610		CONFIG_CMD_IMMAP	* IMMR dump support
611		CONFIG_CMD_IRQ		* irqinfo
612		CONFIG_CMD_ITEST	  Integer/string test of 2 values
613		CONFIG_CMD_JFFS2	* JFFS2 Support
614		CONFIG_CMD_KGDB		* kgdb
615		CONFIG_CMD_LOADB	  loadb
616		CONFIG_CMD_LOADS	  loads
617		CONFIG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
618					  loop, loopw, mtest
619		CONFIG_CMD_MISC		  Misc functions like sleep etc
620		CONFIG_CMD_MMC		* MMC memory mapped support
621		CONFIG_CMD_MII		* MII utility commands
622		CONFIG_CMD_NAND		* NAND support
623		CONFIG_CMD_NET		  bootp, tftpboot, rarpboot
624		CONFIG_CMD_PCI		* pciinfo
625		CONFIG_CMD_PCMCIA		* PCMCIA support
626		CONFIG_CMD_PING		* send ICMP ECHO_REQUEST to network
627					  host
628		CONFIG_CMD_PORTIO	* Port I/O
629		CONFIG_CMD_REGINFO	* Register dump
630		CONFIG_CMD_RUN		  run command in env variable
631		CONFIG_CMD_SAVES	* save S record dump
632		CONFIG_CMD_SCSI		* SCSI Support
633		CONFIG_CMD_SDRAM	* print SDRAM configuration information
634					  (requires CONFIG_CMD_I2C)
635		CONFIG_CMD_SETGETDCR	  Support for DCR Register access
636					  (4xx only)
637		CONFIG_CMD_SPI		* SPI serial bus support
638		CONFIG_CMD_USB		* USB support
639		CONFIG_CMD_VFD		* VFD support (TRAB)
640		CONFIG_CMD_CDP		* Cisco Discover Protocol support
641		CONFIG_CMD_FSL		* Microblaze FSL support
642
643
644		EXAMPLE: If you want all functions except of network
645		support you can write:
646
647		#include "config_cmd_all.h"
648		#undef CONFIG_CMD_NET
649
650	Other Commands:
651		fdt (flattened device tree) command: CONFIG_OF_LIBFDT
652
653	Note:	Don't enable the "icache" and "dcache" commands
654		(configuration option CONFIG_CMD_CACHE) unless you know
655		what you (and your U-Boot users) are doing. Data
656		cache cannot be enabled on systems like the 8xx or
657		8260 (where accesses to the IMMR region must be
658		uncached), and it cannot be disabled on all other
659		systems where we (mis-) use the data cache to hold an
660		initial stack and some data.
661
662
663		XXX - this list needs to get updated!
664
665- Watchdog:
666		CONFIG_WATCHDOG
667		If this variable is defined, it enables watchdog
668		support. There must be support in the platform specific
669		code for a watchdog. For the 8xx and 8260 CPUs, the
670		SIU Watchdog feature is enabled in the SYPCR
671		register.
672
673- U-Boot Version:
674		CONFIG_VERSION_VARIABLE
675		If this variable is defined, an environment variable
676		named "ver" is created by U-Boot showing the U-Boot
677		version as printed by the "version" command.
678		This variable is readonly.
679
680- Real-Time Clock:
681
682		When CONFIG_CMD_DATE is selected, the type of the RTC
683		has to be selected, too. Define exactly one of the
684		following options:
685
686		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
687		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
688		CONFIG_RTC_MC13783	- use MC13783 RTC
689		CONFIG_RTC_MC146818	- use MC146818 RTC
690		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
691		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
692		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
693		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
694		CONFIG_RTC_ISL1208	- use Intersil ISL1208 RTC
695		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC
696		CONFIG_SYS_RTC_DS1337_NOOSC	- Turn off the OSC output for DS1337
697
698		Note that if the RTC uses I2C, then the I2C interface
699		must also be configured. See I2C Support, below.
700
701- Timestamp Support:
702
703		When CONFIG_TIMESTAMP is selected, the timestamp
704		(date and time) of an image is printed by image
705		commands like bootm or iminfo. This option is
706		automatically enabled when you select CONFIG_CMD_DATE .
707
708- Partition Support:
709		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
710		and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
711
712		If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
713		CONFIG_CMD_SCSI) you must configure support for at
714		least one partition type as well.
715
716- IDE Reset method:
717		CONFIG_IDE_RESET_ROUTINE - this is defined in several
718		board configurations files but used nowhere!
719
720		CONFIG_IDE_RESET - is this is defined, IDE Reset will
721		be performed by calling the function
722			ide_set_reset(int reset)
723		which has to be defined in a board specific file
724
725- ATAPI Support:
726		CONFIG_ATAPI
727
728		Set this to enable ATAPI support.
729
730- LBA48 Support
731		CONFIG_LBA48
732
733		Set this to enable support for disks larger than 137GB
734		Also look at CONFIG_SYS_64BIT_LBA ,CONFIG_SYS_64BIT_VSPRINTF and CONFIG_SYS_64BIT_STRTOUL
735		Whithout these , LBA48 support uses 32bit variables and will 'only'
736		support disks up to 2.1TB.
737
738		CONFIG_SYS_64BIT_LBA:
739			When enabled, makes the IDE subsystem use 64bit sector addresses.
740			Default is 32bit.
741
742- SCSI Support:
743		At the moment only there is only support for the
744		SYM53C8XX SCSI controller; define
745		CONFIG_SCSI_SYM53C8XX to enable it.
746
747		CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
748		CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
749		CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
750		maximum numbers of LUNs, SCSI ID's and target
751		devices.
752		CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
753
754- NETWORK Support (PCI):
755		CONFIG_E1000
756		Support for Intel 8254x gigabit chips.
757
758		CONFIG_E1000_FALLBACK_MAC
759		default MAC for empty EEPROM after production.
760
761		CONFIG_EEPRO100
762		Support for Intel 82557/82559/82559ER chips.
763		Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
764		write routine for first time initialisation.
765
766		CONFIG_TULIP
767		Support for Digital 2114x chips.
768		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
769		modem chip initialisation (KS8761/QS6611).
770
771		CONFIG_NATSEMI
772		Support for National dp83815 chips.
773
774		CONFIG_NS8382X
775		Support for National dp8382[01] gigabit chips.
776
777- NETWORK Support (other):
778
779		CONFIG_DRIVER_LAN91C96
780		Support for SMSC's LAN91C96 chips.
781
782			CONFIG_LAN91C96_BASE
783			Define this to hold the physical address
784			of the LAN91C96's I/O space
785
786			CONFIG_LAN91C96_USE_32_BIT
787			Define this to enable 32 bit addressing
788
789		CONFIG_DRIVER_SMC91111
790		Support for SMSC's LAN91C111 chip
791
792			CONFIG_SMC91111_BASE
793			Define this to hold the physical address
794			of the device (I/O space)
795
796			CONFIG_SMC_USE_32_BIT
797			Define this if data bus is 32 bits
798
799			CONFIG_SMC_USE_IOFUNCS
800			Define this to use i/o functions instead of macros
801			(some hardware wont work with macros)
802
803		CONFIG_DRIVER_SMC911X
804		Support for SMSC's LAN911x and LAN921x chips
805
806			CONFIG_DRIVER_SMC911X_BASE
807			Define this to hold the physical address
808			of the device (I/O space)
809
810			CONFIG_DRIVER_SMC911X_32_BIT
811			Define this if data bus is 32 bits
812
813			CONFIG_DRIVER_SMC911X_16_BIT
814			Define this if data bus is 16 bits. If your processor
815			automatically converts one 32 bit word to two 16 bit
816			words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
817
818- USB Support:
819		At the moment only the UHCI host controller is
820		supported (PIP405, MIP405, MPC5200); define
821		CONFIG_USB_UHCI to enable it.
822		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
823		and define CONFIG_USB_STORAGE to enable the USB
824		storage devices.
825		Note:
826		Supported are USB Keyboards and USB Floppy drives
827		(TEAC FD-05PUB).
828		MPC5200 USB requires additional defines:
829			CONFIG_USB_CLOCK
830				for 528 MHz Clock: 0x0001bbbb
831			CONFIG_USB_CONFIG
832				for differential drivers: 0x00001000
833				for single ended drivers: 0x00005000
834			CONFIG_SYS_USB_EVENT_POLL
835				May be defined to allow interrupt polling
836				instead of using asynchronous interrupts
837
838- USB Device:
839		Define the below if you wish to use the USB console.
840		Once firmware is rebuilt from a serial console issue the
841		command "setenv stdin usbtty; setenv stdout usbtty" and
842		attach your USB cable. The Unix command "dmesg" should print
843		it has found a new device. The environment variable usbtty
844		can be set to gserial or cdc_acm to enable your device to
845		appear to a USB host as a Linux gserial device or a
846		Common Device Class Abstract Control Model serial device.
847		If you select usbtty = gserial you should be able to enumerate
848		a Linux host by
849		# modprobe usbserial vendor=0xVendorID product=0xProductID
850		else if using cdc_acm, simply setting the environment
851		variable usbtty to be cdc_acm should suffice. The following
852		might be defined in YourBoardName.h
853
854			CONFIG_USB_DEVICE
855			Define this to build a UDC device
856
857			CONFIG_USB_TTY
858			Define this to have a tty type of device available to
859			talk to the UDC device
860
861			CONFIG_SYS_CONSOLE_IS_IN_ENV
862			Define this if you want stdin, stdout &/or stderr to
863			be set to usbtty.
864
865			mpc8xx:
866				CONFIG_SYS_USB_EXTC_CLK 0xBLAH
867				Derive USB clock from external clock "blah"
868				- CONFIG_SYS_USB_EXTC_CLK 0x02
869
870				CONFIG_SYS_USB_BRG_CLK 0xBLAH
871				Derive USB clock from brgclk
872				- CONFIG_SYS_USB_BRG_CLK 0x04
873
874		If you have a USB-IF assigned VendorID then you may wish to
875		define your own vendor specific values either in BoardName.h
876		or directly in usbd_vendor_info.h. If you don't define
877		CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
878		CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
879		should pretend to be a Linux device to it's target host.
880
881			CONFIG_USBD_MANUFACTURER
882			Define this string as the name of your company for
883			- CONFIG_USBD_MANUFACTURER "my company"
884
885			CONFIG_USBD_PRODUCT_NAME
886			Define this string as the name of your product
887			- CONFIG_USBD_PRODUCT_NAME "acme usb device"
888
889			CONFIG_USBD_VENDORID
890			Define this as your assigned Vendor ID from the USB
891			Implementors Forum. This *must* be a genuine Vendor ID
892			to avoid polluting the USB namespace.
893			- CONFIG_USBD_VENDORID 0xFFFF
894
895			CONFIG_USBD_PRODUCTID
896			Define this as the unique Product ID
897			for your device
898			- CONFIG_USBD_PRODUCTID 0xFFFF
899
900
901- MMC Support:
902		The MMC controller on the Intel PXA is supported. To
903		enable this define CONFIG_MMC. The MMC can be
904		accessed from the boot prompt by mapping the device
905		to physical memory similar to flash. Command line is
906		enabled with CONFIG_CMD_MMC. The MMC driver also works with
907		the FAT fs. This is enabled with CONFIG_CMD_FAT.
908
909- Journaling Flash filesystem support:
910		CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
911		CONFIG_JFFS2_NAND_DEV
912		Define these for a default partition on a NAND device
913
914		CONFIG_SYS_JFFS2_FIRST_SECTOR,
915		CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
916		Define these for a default partition on a NOR device
917
918		CONFIG_SYS_JFFS_CUSTOM_PART
919		Define this to create an own partition. You have to provide a
920		function struct part_info* jffs2_part_info(int part_num)
921
922		If you define only one JFFS2 partition you may also want to
923		#define CONFIG_SYS_JFFS_SINGLE_PART	1
924		to disable the command chpart. This is the default when you
925		have not defined a custom partition
926
927- Keyboard Support:
928		CONFIG_ISA_KEYBOARD
929
930		Define this to enable standard (PC-Style) keyboard
931		support
932
933		CONFIG_I8042_KBD
934		Standard PC keyboard driver with US (is default) and
935		GERMAN key layout (switch via environment 'keymap=de') support.
936		Export function i8042_kbd_init, i8042_tstc and i8042_getc
937		for cfb_console. Supports cursor blinking.
938
939- Video support:
940		CONFIG_VIDEO
941
942		Define this to enable video support (for output to
943		video).
944
945		CONFIG_VIDEO_CT69000
946
947		Enable Chips & Technologies 69000 Video chip
948
949		CONFIG_VIDEO_SMI_LYNXEM
950		Enable Silicon Motion SMI 712/710/810 Video chip. The
951		video output is selected via environment 'videoout'
952		(1 = LCD and 2 = CRT). If videoout is undefined, CRT is
953		assumed.
954
955		For the CT69000 and SMI_LYNXEM drivers, videomode is
956		selected via environment 'videomode'. Two different ways
957		are possible:
958		- "videomode=num"   'num' is a standard LiLo mode numbers.
959		Following standard modes are supported	(* is default):
960
961		      Colors	640x480 800x600 1024x768 1152x864 1280x1024
962		-------------+---------------------------------------------
963		      8 bits |	0x301*	0x303	 0x305	  0x161	    0x307
964		     15 bits |	0x310	0x313	 0x316	  0x162	    0x319
965		     16 bits |	0x311	0x314	 0x317	  0x163	    0x31A
966		     24 bits |	0x312	0x315	 0x318	    ?	    0x31B
967		-------------+---------------------------------------------
968		(i.e. setenv videomode 317; saveenv; reset;)
969
970		- "videomode=bootargs" all the video parameters are parsed
971		from the bootargs. (See drivers/video/videomodes.c)
972
973
974		CONFIG_VIDEO_SED13806
975		Enable Epson SED13806 driver. This driver supports 8bpp
976		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
977		or CONFIG_VIDEO_SED13806_16BPP
978
979- Keyboard Support:
980		CONFIG_KEYBOARD
981
982		Define this to enable a custom keyboard support.
983		This simply calls drv_keyboard_init() which must be
984		defined in your board-specific files.
985		The only board using this so far is RBC823.
986
987- LCD Support:	CONFIG_LCD
988
989		Define this to enable LCD support (for output to LCD
990		display); also select one of the supported displays
991		by defining one of these:
992
993		CONFIG_ATMEL_LCD:
994
995			HITACHI TX09D70VM1CCA, 3.5", 240x320.
996
997		CONFIG_NEC_NL6448AC33:
998
999			NEC NL6448AC33-18. Active, color, single scan.
1000
1001		CONFIG_NEC_NL6448BC20
1002
1003			NEC NL6448BC20-08. 6.5", 640x480.
1004			Active, color, single scan.
1005
1006		CONFIG_NEC_NL6448BC33_54
1007
1008			NEC NL6448BC33-54. 10.4", 640x480.
1009			Active, color, single scan.
1010
1011		CONFIG_SHARP_16x9
1012
1013			Sharp 320x240. Active, color, single scan.
1014			It isn't 16x9, and I am not sure what it is.
1015
1016		CONFIG_SHARP_LQ64D341
1017
1018			Sharp LQ64D341 display, 640x480.
1019			Active, color, single scan.
1020
1021		CONFIG_HLD1045
1022
1023			HLD1045 display, 640x480.
1024			Active, color, single scan.
1025
1026		CONFIG_OPTREX_BW
1027
1028			Optrex	 CBL50840-2 NF-FW 99 22 M5
1029			or
1030			Hitachi	 LMG6912RPFC-00T
1031			or
1032			Hitachi	 SP14Q002
1033
1034			320x240. Black & white.
1035
1036		Normally display is black on white background; define
1037		CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1038
1039- Splash Screen Support: CONFIG_SPLASH_SCREEN
1040
1041		If this option is set, the environment is checked for
1042		a variable "splashimage". If found, the usual display
1043		of logo, copyright and system information on the LCD
1044		is suppressed and the BMP image at the address
1045		specified in "splashimage" is loaded instead. The
1046		console is redirected to the "nulldev", too. This
1047		allows for a "silent" boot where a splash screen is
1048		loaded very quickly after power-on.
1049
1050- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1051
1052		If this option is set, additionally to standard BMP
1053		images, gzipped BMP images can be displayed via the
1054		splashscreen support or the bmp command.
1055
1056- Compression support:
1057		CONFIG_BZIP2
1058
1059		If this option is set, support for bzip2 compressed
1060		images is included. If not, only uncompressed and gzip
1061		compressed images are supported.
1062
1063		NOTE: the bzip2 algorithm requires a lot of RAM, so
1064		the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1065		be at least 4MB.
1066
1067		CONFIG_LZMA
1068
1069		If this option is set, support for lzma compressed
1070		images is included.
1071
1072		Note: The LZMA algorithm adds between 2 and 4KB of code and it
1073		requires an amount of dynamic memory that is given by the
1074		formula:
1075
1076			(1846 + 768 << (lc + lp)) * sizeof(uint16)
1077
1078		Where lc and lp stand for, respectively, Literal context bits
1079		and Literal pos bits.
1080
1081		This value is upper-bounded by 14MB in the worst case. Anyway,
1082		for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1083		total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1084		a very small buffer.
1085
1086		Use the lzmainfo tool to determinate the lc and lp values and
1087		then calculate the amount of needed dynamic memory (ensuring
1088		the appropriate CONFIG_SYS_MALLOC_LEN value).
1089
1090- MII/PHY support:
1091		CONFIG_PHY_ADDR
1092
1093		The address of PHY on MII bus.
1094
1095		CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1096
1097		The clock frequency of the MII bus
1098
1099		CONFIG_PHY_GIGE
1100
1101		If this option is set, support for speed/duplex
1102		detection of gigabit PHY is included.
1103
1104		CONFIG_PHY_RESET_DELAY
1105
1106		Some PHY like Intel LXT971A need extra delay after
1107		reset before any MII register access is possible.
1108		For such PHY, set this option to the usec delay
1109		required. (minimum 300usec for LXT971A)
1110
1111		CONFIG_PHY_CMD_DELAY (ppc4xx)
1112
1113		Some PHY like Intel LXT971A need extra delay after
1114		command issued before MII status register can be read
1115
1116- Ethernet address:
1117		CONFIG_ETHADDR
1118		CONFIG_ETH1ADDR
1119		CONFIG_ETH2ADDR
1120		CONFIG_ETH3ADDR
1121		CONFIG_ETH4ADDR
1122		CONFIG_ETH5ADDR
1123
1124		Define a default value for Ethernet address to use
1125		for the respective Ethernet interface, in case this
1126		is not determined automatically.
1127
1128- IP address:
1129		CONFIG_IPADDR
1130
1131		Define a default value for the IP address to use for
1132		the default Ethernet interface, in case this is not
1133		determined through e.g. bootp.
1134
1135- Server IP address:
1136		CONFIG_SERVERIP
1137
1138		Defines a default value for the IP address of a TFTP
1139		server to contact when using the "tftboot" command.
1140
1141- Multicast TFTP Mode:
1142		CONFIG_MCAST_TFTP
1143
1144		Defines whether you want to support multicast TFTP as per
1145		rfc-2090; for example to work with atftp.  Lets lots of targets
1146		tftp down the same boot image concurrently.  Note: the Ethernet
1147		driver in use must provide a function: mcast() to join/leave a
1148		multicast group.
1149
1150		CONFIG_BOOTP_RANDOM_DELAY
1151- BOOTP Recovery Mode:
1152		CONFIG_BOOTP_RANDOM_DELAY
1153
1154		If you have many targets in a network that try to
1155		boot using BOOTP, you may want to avoid that all
1156		systems send out BOOTP requests at precisely the same
1157		moment (which would happen for instance at recovery
1158		from a power failure, when all systems will try to
1159		boot, thus flooding the BOOTP server. Defining
1160		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1161		inserted before sending out BOOTP requests. The
1162		following delays are inserted then:
1163
1164		1st BOOTP request:	delay 0 ... 1 sec
1165		2nd BOOTP request:	delay 0 ... 2 sec
1166		3rd BOOTP request:	delay 0 ... 4 sec
1167		4th and following
1168		BOOTP requests:		delay 0 ... 8 sec
1169
1170- DHCP Advanced Options:
1171		You can fine tune the DHCP functionality by defining
1172		CONFIG_BOOTP_* symbols:
1173
1174		CONFIG_BOOTP_SUBNETMASK
1175		CONFIG_BOOTP_GATEWAY
1176		CONFIG_BOOTP_HOSTNAME
1177		CONFIG_BOOTP_NISDOMAIN
1178		CONFIG_BOOTP_BOOTPATH
1179		CONFIG_BOOTP_BOOTFILESIZE
1180		CONFIG_BOOTP_DNS
1181		CONFIG_BOOTP_DNS2
1182		CONFIG_BOOTP_SEND_HOSTNAME
1183		CONFIG_BOOTP_NTPSERVER
1184		CONFIG_BOOTP_TIMEOFFSET
1185		CONFIG_BOOTP_VENDOREX
1186
1187		CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1188		environment variable, not the BOOTP server.
1189
1190		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1191		serverip from a DHCP server, it is possible that more
1192		than one DNS serverip is offered to the client.
1193		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1194		serverip will be stored in the additional environment
1195		variable "dnsip2". The first DNS serverip is always
1196		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1197		is defined.
1198
1199		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1200		to do a dynamic update of a DNS server. To do this, they
1201		need the hostname of the DHCP requester.
1202		If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1203		of the "hostname" environment variable is passed as
1204		option 12 to the DHCP server.
1205
1206		CONFIG_BOOTP_DHCP_REQUEST_DELAY
1207
1208		A 32bit value in microseconds for a delay between
1209		receiving a "DHCP Offer" and sending the "DHCP Request".
1210		This fixes a problem with certain DHCP servers that don't
1211		respond 100% of the time to a "DHCP request". E.g. On an
1212		AT91RM9200 processor running at 180MHz, this delay needed
1213		to be *at least* 15,000 usec before a Windows Server 2003
1214		DHCP server would reply 100% of the time. I recommend at
1215		least 50,000 usec to be safe. The alternative is to hope
1216		that one of the retries will be successful but note that
1217		the DHCP timeout and retry process takes a longer than
1218		this delay.
1219
1220 - CDP Options:
1221		CONFIG_CDP_DEVICE_ID
1222
1223		The device id used in CDP trigger frames.
1224
1225		CONFIG_CDP_DEVICE_ID_PREFIX
1226
1227		A two character string which is prefixed to the MAC address
1228		of the device.
1229
1230		CONFIG_CDP_PORT_ID
1231
1232		A printf format string which contains the ascii name of
1233		the port. Normally is set to "eth%d" which sets
1234		eth0 for the first Ethernet, eth1 for the second etc.
1235
1236		CONFIG_CDP_CAPABILITIES
1237
1238		A 32bit integer which indicates the device capabilities;
1239		0x00000010 for a normal host which does not forwards.
1240
1241		CONFIG_CDP_VERSION
1242
1243		An ascii string containing the version of the software.
1244
1245		CONFIG_CDP_PLATFORM
1246
1247		An ascii string containing the name of the platform.
1248
1249		CONFIG_CDP_TRIGGER
1250
1251		A 32bit integer sent on the trigger.
1252
1253		CONFIG_CDP_POWER_CONSUMPTION
1254
1255		A 16bit integer containing the power consumption of the
1256		device in .1 of milliwatts.
1257
1258		CONFIG_CDP_APPLIANCE_VLAN_TYPE
1259
1260		A byte containing the id of the VLAN.
1261
1262- Status LED:	CONFIG_STATUS_LED
1263
1264		Several configurations allow to display the current
1265		status using a LED. For instance, the LED will blink
1266		fast while running U-Boot code, stop blinking as
1267		soon as a reply to a BOOTP request was received, and
1268		start blinking slow once the Linux kernel is running
1269		(supported by a status LED driver in the Linux
1270		kernel). Defining CONFIG_STATUS_LED enables this
1271		feature in U-Boot.
1272
1273- CAN Support:	CONFIG_CAN_DRIVER
1274
1275		Defining CONFIG_CAN_DRIVER enables CAN driver support
1276		on those systems that support this (optional)
1277		feature, like the TQM8xxL modules.
1278
1279- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1280
1281		These enable I2C serial bus commands. Defining either of
1282		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1283		include the appropriate I2C driver for the selected CPU.
1284
1285		This will allow you to use i2c commands at the u-boot
1286		command line (as long as you set CONFIG_CMD_I2C in
1287		CONFIG_COMMANDS) and communicate with i2c based realtime
1288		clock chips. See common/cmd_i2c.c for a description of the
1289		command line interface.
1290
1291		CONFIG_I2C_CMD_TREE is a recommended option that places
1292		all I2C commands under a single 'i2c' root command.  The
1293		older 'imm', 'imd', 'iprobe' etc. commands are considered
1294		deprecated and may disappear in the future.
1295
1296		CONFIG_HARD_I2C selects a hardware I2C controller.
1297
1298		CONFIG_SOFT_I2C configures u-boot to use a software (aka
1299		bit-banging) driver instead of CPM or similar hardware
1300		support for I2C.
1301
1302		There are several other quantities that must also be
1303		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1304
1305		In both cases you will need to define CONFIG_SYS_I2C_SPEED
1306		to be the frequency (in Hz) at which you wish your i2c bus
1307		to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1308		the CPU's i2c node address).
1309
1310		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1311		sets the CPU up as a master node and so its address should
1312		therefore be cleared to 0 (See, eg, MPC823e User's Manual
1313		p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
1314
1315		That's all that's required for CONFIG_HARD_I2C.
1316
1317		If you use the software i2c interface (CONFIG_SOFT_I2C)
1318		then the following macros need to be defined (examples are
1319		from include/configs/lwmon.h):
1320
1321		I2C_INIT
1322
1323		(Optional). Any commands necessary to enable the I2C
1324		controller or configure ports.
1325
1326		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
1327
1328		I2C_PORT
1329
1330		(Only for MPC8260 CPU). The I/O port to use (the code
1331		assumes both bits are on the same port). Valid values
1332		are 0..3 for ports A..D.
1333
1334		I2C_ACTIVE
1335
1336		The code necessary to make the I2C data line active
1337		(driven).  If the data line is open collector, this
1338		define can be null.
1339
1340		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1341
1342		I2C_TRISTATE
1343
1344		The code necessary to make the I2C data line tri-stated
1345		(inactive).  If the data line is open collector, this
1346		define can be null.
1347
1348		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1349
1350		I2C_READ
1351
1352		Code that returns TRUE if the I2C data line is high,
1353		FALSE if it is low.
1354
1355		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1356
1357		I2C_SDA(bit)
1358
1359		If <bit> is TRUE, sets the I2C data line high. If it
1360		is FALSE, it clears it (low).
1361
1362		eg: #define I2C_SDA(bit) \
1363			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1364			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1365
1366		I2C_SCL(bit)
1367
1368		If <bit> is TRUE, sets the I2C clock line high. If it
1369		is FALSE, it clears it (low).
1370
1371		eg: #define I2C_SCL(bit) \
1372			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1373			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1374
1375		I2C_DELAY
1376
1377		This delay is invoked four times per clock cycle so this
1378		controls the rate of data transfer.  The data rate thus
1379		is 1 / (I2C_DELAY * 4). Often defined to be something
1380		like:
1381
1382		#define I2C_DELAY  udelay(2)
1383
1384		CONFIG_SYS_I2C_INIT_BOARD
1385
1386		When a board is reset during an i2c bus transfer
1387		chips might think that the current transfer is still
1388		in progress. On some boards it is possible to access
1389		the i2c SCLK line directly, either by using the
1390		processor pin as a GPIO or by having a second pin
1391		connected to the bus. If this option is defined a
1392		custom i2c_init_board() routine in boards/xxx/board.c
1393		is run early in the boot sequence.
1394
1395		CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1396
1397		This option enables configuration of bi_iic_fast[] flags
1398		in u-boot bd_info structure based on u-boot environment
1399		variable "i2cfast". (see also i2cfast)
1400
1401		CONFIG_I2C_MULTI_BUS
1402
1403		This option allows the use of multiple I2C buses, each of which
1404		must have a controller.  At any point in time, only one bus is
1405		active.  To switch to a different bus, use the 'i2c dev' command.
1406		Note that bus numbering is zero-based.
1407
1408		CONFIG_SYS_I2C_NOPROBES
1409
1410		This option specifies a list of I2C devices that will be skipped
1411		when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1412		command).  If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1413		pairs.	Otherwise, specify a 1D array of device addresses
1414
1415		e.g.
1416			#undef	CONFIG_I2C_MULTI_BUS
1417			#define CONFIG_SYS_I2C_NOPROBES	{0x50,0x68}
1418
1419		will skip addresses 0x50 and 0x68 on a board with one I2C bus
1420
1421			#define	CONFIG_I2C_MULTI_BUS
1422			#define CONFIG_SYS_I2C_MULTI_NOPROBES	{{0,0x50},{0,0x68},{1,0x54}}
1423
1424		will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1425
1426		CONFIG_SYS_SPD_BUS_NUM
1427
1428		If defined, then this indicates the I2C bus number for DDR SPD.
1429		If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1430
1431		CONFIG_SYS_RTC_BUS_NUM
1432
1433		If defined, then this indicates the I2C bus number for the RTC.
1434		If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1435
1436		CONFIG_SYS_DTT_BUS_NUM
1437
1438		If defined, then this indicates the I2C bus number for the DTT.
1439		If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1440
1441		CONFIG_SYS_I2C_DTT_ADDR:
1442
1443		If defined, specifies the I2C address of the DTT device.
1444		If not defined, then U-Boot uses predefined value for
1445		specified DTT device.
1446
1447		CONFIG_FSL_I2C
1448
1449		Define this option if you want to use Freescale's I2C driver in
1450		drivers/i2c/fsl_i2c.c.
1451
1452		CONFIG_I2C_MUX
1453
1454		Define this option if you have I2C devices reached over 1 .. n
1455		I2C Muxes like the pca9544a. This option addes a new I2C
1456		Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1457		new I2C Bus to the existing I2C Busses. If you select the
1458		new Bus with "i2c dev", u-bbot sends first the commandos for
1459		the muxes to activate this new "bus".
1460
1461		CONFIG_I2C_MULTI_BUS must be also defined, to use this
1462		feature!
1463
1464		Example:
1465		Adding a new I2C Bus reached over 2 pca9544a muxes
1466			The First mux with address 70 and channel 6
1467			The Second mux with address 71 and channel 4
1468
1469		=> i2c bus pca9544a:70:6:pca9544a:71:4
1470
1471		Use the "i2c bus" command without parameter, to get a list
1472		of I2C Busses with muxes:
1473
1474		=> i2c bus
1475		Busses reached over muxes:
1476		Bus ID: 2
1477		  reached over Mux(es):
1478		    pca9544a@70 ch: 4
1479		Bus ID: 3
1480		  reached over Mux(es):
1481		    pca9544a@70 ch: 6
1482		    pca9544a@71 ch: 4
1483		=>
1484
1485		If you now switch to the new I2C Bus 3 with "i2c dev 3"
1486		u-boot sends First the Commando to the mux@70 to enable
1487		channel 6, and then the Commando to the mux@71 to enable
1488		the channel 4.
1489
1490		After that, you can use the "normal" i2c commands as
1491		usual, to communicate with your I2C devices behind
1492		the 2 muxes.
1493
1494		This option is actually implemented for the bitbanging
1495		algorithm in common/soft_i2c.c and for the Hardware I2C
1496		Bus on the MPC8260. But it should be not so difficult
1497		to add this option to other architectures.
1498
1499
1500- SPI Support:	CONFIG_SPI
1501
1502		Enables SPI driver (so far only tested with
1503		SPI EEPROM, also an instance works with Crystal A/D and
1504		D/As on the SACSng board)
1505
1506		CONFIG_SPI_X
1507
1508		Enables extended (16-bit) SPI EEPROM addressing.
1509		(symmetrical to CONFIG_I2C_X)
1510
1511		CONFIG_SOFT_SPI
1512
1513		Enables a software (bit-bang) SPI driver rather than
1514		using hardware support. This is a general purpose
1515		driver that only requires three general I/O port pins
1516		(two outputs, one input) to function. If this is
1517		defined, the board configuration must define several
1518		SPI configuration items (port pins to use, etc). For
1519		an example, see include/configs/sacsng.h.
1520
1521		CONFIG_HARD_SPI
1522
1523		Enables a hardware SPI driver for general-purpose reads
1524		and writes.  As with CONFIG_SOFT_SPI, the board configuration
1525		must define a list of chip-select function pointers.
1526		Currently supported on some MPC8xxx processors.  For an
1527		example, see include/configs/mpc8349emds.h.
1528
1529		CONFIG_MXC_SPI
1530
1531		Enables the driver for the SPI controllers on i.MX and MXC
1532		SoCs. Currently only i.MX31 is supported.
1533
1534- FPGA Support: CONFIG_FPGA
1535
1536		Enables FPGA subsystem.
1537
1538		CONFIG_FPGA_<vendor>
1539
1540		Enables support for specific chip vendors.
1541		(ALTERA, XILINX)
1542
1543		CONFIG_FPGA_<family>
1544
1545		Enables support for FPGA family.
1546		(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1547
1548		CONFIG_FPGA_COUNT
1549
1550		Specify the number of FPGA devices to support.
1551
1552		CONFIG_SYS_FPGA_PROG_FEEDBACK
1553
1554		Enable printing of hash marks during FPGA configuration.
1555
1556		CONFIG_SYS_FPGA_CHECK_BUSY
1557
1558		Enable checks on FPGA configuration interface busy
1559		status by the configuration function. This option
1560		will require a board or device specific function to
1561		be written.
1562
1563		CONFIG_FPGA_DELAY
1564
1565		If defined, a function that provides delays in the FPGA
1566		configuration driver.
1567
1568		CONFIG_SYS_FPGA_CHECK_CTRLC
1569		Allow Control-C to interrupt FPGA configuration
1570
1571		CONFIG_SYS_FPGA_CHECK_ERROR
1572
1573		Check for configuration errors during FPGA bitfile
1574		loading. For example, abort during Virtex II
1575		configuration if the INIT_B line goes low (which
1576		indicated a CRC error).
1577
1578		CONFIG_SYS_FPGA_WAIT_INIT
1579
1580		Maximum time to wait for the INIT_B line to deassert
1581		after PROB_B has been deasserted during a Virtex II
1582		FPGA configuration sequence. The default time is 500
1583		ms.
1584
1585		CONFIG_SYS_FPGA_WAIT_BUSY
1586
1587		Maximum time to wait for BUSY to deassert during
1588		Virtex II FPGA configuration. The default is 5 ms.
1589
1590		CONFIG_SYS_FPGA_WAIT_CONFIG
1591
1592		Time to wait after FPGA configuration. The default is
1593		200 ms.
1594
1595- Configuration Management:
1596		CONFIG_IDENT_STRING
1597
1598		If defined, this string will be added to the U-Boot
1599		version information (U_BOOT_VERSION)
1600
1601- Vendor Parameter Protection:
1602
1603		U-Boot considers the values of the environment
1604		variables "serial#" (Board Serial Number) and
1605		"ethaddr" (Ethernet Address) to be parameters that
1606		are set once by the board vendor / manufacturer, and
1607		protects these variables from casual modification by
1608		the user. Once set, these variables are read-only,
1609		and write or delete attempts are rejected. You can
1610		change this behaviour:
1611
1612		If CONFIG_ENV_OVERWRITE is #defined in your config
1613		file, the write protection for vendor parameters is
1614		completely disabled. Anybody can change or delete
1615		these parameters.
1616
1617		Alternatively, if you #define _both_ CONFIG_ETHADDR
1618		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1619		Ethernet address is installed in the environment,
1620		which can be changed exactly ONCE by the user. [The
1621		serial# is unaffected by this, i. e. it remains
1622		read-only.]
1623
1624- Protected RAM:
1625		CONFIG_PRAM
1626
1627		Define this variable to enable the reservation of
1628		"protected RAM", i. e. RAM which is not overwritten
1629		by U-Boot. Define CONFIG_PRAM to hold the number of
1630		kB you want to reserve for pRAM. You can overwrite
1631		this default value by defining an environment
1632		variable "pram" to the number of kB you want to
1633		reserve. Note that the board info structure will
1634		still show the full amount of RAM. If pRAM is
1635		reserved, a new environment variable "mem" will
1636		automatically be defined to hold the amount of
1637		remaining RAM in a form that can be passed as boot
1638		argument to Linux, for instance like that:
1639
1640			setenv bootargs ... mem=\${mem}
1641			saveenv
1642
1643		This way you can tell Linux not to use this memory,
1644		either, which results in a memory region that will
1645		not be affected by reboots.
1646
1647		*WARNING* If your board configuration uses automatic
1648		detection of the RAM size, you must make sure that
1649		this memory test is non-destructive. So far, the
1650		following board configurations are known to be
1651		"pRAM-clean":
1652
1653			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1654			HERMES, IP860, RPXlite, LWMON, LANTEC,
1655			PCU_E, FLAGADM, TQM8260
1656
1657- Error Recovery:
1658		CONFIG_PANIC_HANG
1659
1660		Define this variable to stop the system in case of a
1661		fatal error, so that you have to reset it manually.
1662		This is probably NOT a good idea for an embedded
1663		system where you want the system to reboot
1664		automatically as fast as possible, but it may be
1665		useful during development since you can try to debug
1666		the conditions that lead to the situation.
1667
1668		CONFIG_NET_RETRY_COUNT
1669
1670		This variable defines the number of retries for
1671		network operations like ARP, RARP, TFTP, or BOOTP
1672		before giving up the operation. If not defined, a
1673		default value of 5 is used.
1674
1675		CONFIG_ARP_TIMEOUT
1676
1677		Timeout waiting for an ARP reply in milliseconds.
1678
1679- Command Interpreter:
1680		CONFIG_AUTO_COMPLETE
1681
1682		Enable auto completion of commands using TAB.
1683
1684		Note that this feature has NOT been implemented yet
1685		for the "hush" shell.
1686
1687
1688		CONFIG_SYS_HUSH_PARSER
1689
1690		Define this variable to enable the "hush" shell (from
1691		Busybox) as command line interpreter, thus enabling
1692		powerful command line syntax like
1693		if...then...else...fi conditionals or `&&' and '||'
1694		constructs ("shell scripts").
1695
1696		If undefined, you get the old, much simpler behaviour
1697		with a somewhat smaller memory footprint.
1698
1699
1700		CONFIG_SYS_PROMPT_HUSH_PS2
1701
1702		This defines the secondary prompt string, which is
1703		printed when the command interpreter needs more input
1704		to complete a command. Usually "> ".
1705
1706	Note:
1707
1708		In the current implementation, the local variables
1709		space and global environment variables space are
1710		separated. Local variables are those you define by
1711		simply typing `name=value'. To access a local
1712		variable later on, you have write `$name' or
1713		`${name}'; to execute the contents of a variable
1714		directly type `$name' at the command prompt.
1715
1716		Global environment variables are those you use
1717		setenv/printenv to work with. To run a command stored
1718		in such a variable, you need to use the run command,
1719		and you must not use the '$' sign to access them.
1720
1721		To store commands and special characters in a
1722		variable, please use double quotation marks
1723		surrounding the whole text of the variable, instead
1724		of the backslashes before semicolons and special
1725		symbols.
1726
1727- Commandline Editing and History:
1728		CONFIG_CMDLINE_EDITING
1729
1730		Enable editing and History functions for interactive
1731		commandline input operations
1732
1733- Default Environment:
1734		CONFIG_EXTRA_ENV_SETTINGS
1735
1736		Define this to contain any number of null terminated
1737		strings (variable = value pairs) that will be part of
1738		the default environment compiled into the boot image.
1739
1740		For example, place something like this in your
1741		board's config file:
1742
1743		#define CONFIG_EXTRA_ENV_SETTINGS \
1744			"myvar1=value1\0" \
1745			"myvar2=value2\0"
1746
1747		Warning: This method is based on knowledge about the
1748		internal format how the environment is stored by the
1749		U-Boot code. This is NOT an official, exported
1750		interface! Although it is unlikely that this format
1751		will change soon, there is no guarantee either.
1752		You better know what you are doing here.
1753
1754		Note: overly (ab)use of the default environment is
1755		discouraged. Make sure to check other ways to preset
1756		the environment like the autoscript function or the
1757		boot command first.
1758
1759- DataFlash Support:
1760		CONFIG_HAS_DATAFLASH
1761
1762		Defining this option enables DataFlash features and
1763		allows to read/write in Dataflash via the standard
1764		commands cp, md...
1765
1766- SystemACE Support:
1767		CONFIG_SYSTEMACE
1768
1769		Adding this option adds support for Xilinx SystemACE
1770		chips attached via some sort of local bus. The address
1771		of the chip must also be defined in the
1772		CONFIG_SYS_SYSTEMACE_BASE macro. For example:
1773
1774		#define CONFIG_SYSTEMACE
1775		#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
1776
1777		When SystemACE support is added, the "ace" device type
1778		becomes available to the fat commands, i.e. fatls.
1779
1780- TFTP Fixed UDP Port:
1781		CONFIG_TFTP_PORT
1782
1783		If this is defined, the environment variable tftpsrcp
1784		is used to supply the TFTP UDP source port value.
1785		If tftpsrcp isn't defined, the normal pseudo-random port
1786		number generator is used.
1787
1788		Also, the environment variable tftpdstp is used to supply
1789		the TFTP UDP destination port value.  If tftpdstp isn't
1790		defined, the normal port 69 is used.
1791
1792		The purpose for tftpsrcp is to allow a TFTP server to
1793		blindly start the TFTP transfer using the pre-configured
1794		target IP address and UDP port. This has the effect of
1795		"punching through" the (Windows XP) firewall, allowing
1796		the remainder of the TFTP transfer to proceed normally.
1797		A better solution is to properly configure the firewall,
1798		but sometimes that is not allowed.
1799
1800- Show boot progress:
1801		CONFIG_SHOW_BOOT_PROGRESS
1802
1803		Defining this option allows to add some board-
1804		specific code (calling a user-provided function
1805		"show_boot_progress(int)") that enables you to show
1806		the system's boot progress on some display (for
1807		example, some LED's) on your board. At the moment,
1808		the following checkpoints are implemented:
1809
1810- Automatic software updates via TFTP server
1811		CONFIG_UPDATE_TFTP
1812		CONFIG_UPDATE_TFTP_CNT_MAX
1813		CONFIG_UPDATE_TFTP_MSEC_MAX
1814
1815		These options enable and control the auto-update feature;
1816		for a more detailed description refer to doc/README.update.
1817
1818Legacy uImage format:
1819
1820  Arg	Where			When
1821    1	common/cmd_bootm.c	before attempting to boot an image
1822   -1	common/cmd_bootm.c	Image header has bad	 magic number
1823    2	common/cmd_bootm.c	Image header has correct magic number
1824   -2	common/cmd_bootm.c	Image header has bad	 checksum
1825    3	common/cmd_bootm.c	Image header has correct checksum
1826   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1827    4	common/cmd_bootm.c	Image data   has correct checksum
1828   -4	common/cmd_bootm.c	Image is for unsupported architecture
1829    5	common/cmd_bootm.c	Architecture check OK
1830   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi)
1831    6	common/cmd_bootm.c	Image Type check OK
1832   -6	common/cmd_bootm.c	gunzip uncompression error
1833   -7	common/cmd_bootm.c	Unimplemented compression type
1834    7	common/cmd_bootm.c	Uncompression OK
1835    8	common/cmd_bootm.c	No uncompress/copy overwrite error
1836   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1837
1838    9	common/image.c		Start initial ramdisk verification
1839  -10	common/image.c		Ramdisk header has bad	   magic number
1840  -11	common/image.c		Ramdisk header has bad	   checksum
1841   10	common/image.c		Ramdisk header is OK
1842  -12	common/image.c		Ramdisk data   has bad	   checksum
1843   11	common/image.c		Ramdisk data   has correct checksum
1844   12	common/image.c		Ramdisk verification complete, start loading
1845  -13	common/image.c		Wrong Image Type (not PPC Linux ramdisk)
1846   13	common/image.c		Start multifile image verification
1847   14	common/image.c		No initial ramdisk, no multifile, continue.
1848
1849   15	lib_<arch>/bootm.c	All preparation done, transferring control to OS
1850
1851  -30	lib_ppc/board.c		Fatal error, hang the system
1852  -31	post/post.c		POST test failed, detected by post_output_backlog()
1853  -32	post/post.c		POST test failed, detected by post_run_single()
1854
1855   34	common/cmd_doc.c	before loading a Image from a DOC device
1856  -35	common/cmd_doc.c	Bad usage of "doc" command
1857   35	common/cmd_doc.c	correct usage of "doc" command
1858  -36	common/cmd_doc.c	No boot device
1859   36	common/cmd_doc.c	correct boot device
1860  -37	common/cmd_doc.c	Unknown Chip ID on boot device
1861   37	common/cmd_doc.c	correct chip ID found, device available
1862  -38	common/cmd_doc.c	Read Error on boot device
1863   38	common/cmd_doc.c	reading Image header from DOC device OK
1864  -39	common/cmd_doc.c	Image header has bad magic number
1865   39	common/cmd_doc.c	Image header has correct magic number
1866  -40	common/cmd_doc.c	Error reading Image from DOC device
1867   40	common/cmd_doc.c	Image header has correct magic number
1868   41	common/cmd_ide.c	before loading a Image from a IDE device
1869  -42	common/cmd_ide.c	Bad usage of "ide" command
1870   42	common/cmd_ide.c	correct usage of "ide" command
1871  -43	common/cmd_ide.c	No boot device
1872   43	common/cmd_ide.c	boot device found
1873  -44	common/cmd_ide.c	Device not available
1874   44	common/cmd_ide.c	Device available
1875  -45	common/cmd_ide.c	wrong partition selected
1876   45	common/cmd_ide.c	partition selected
1877  -46	common/cmd_ide.c	Unknown partition table
1878   46	common/cmd_ide.c	valid partition table found
1879  -47	common/cmd_ide.c	Invalid partition type
1880   47	common/cmd_ide.c	correct partition type
1881  -48	common/cmd_ide.c	Error reading Image Header on boot device
1882   48	common/cmd_ide.c	reading Image Header from IDE device OK
1883  -49	common/cmd_ide.c	Image header has bad magic number
1884   49	common/cmd_ide.c	Image header has correct magic number
1885  -50	common/cmd_ide.c	Image header has bad	 checksum
1886   50	common/cmd_ide.c	Image header has correct checksum
1887  -51	common/cmd_ide.c	Error reading Image from IDE device
1888   51	common/cmd_ide.c	reading Image from IDE device OK
1889   52	common/cmd_nand.c	before loading a Image from a NAND device
1890  -53	common/cmd_nand.c	Bad usage of "nand" command
1891   53	common/cmd_nand.c	correct usage of "nand" command
1892  -54	common/cmd_nand.c	No boot device
1893   54	common/cmd_nand.c	boot device found
1894  -55	common/cmd_nand.c	Unknown Chip ID on boot device
1895   55	common/cmd_nand.c	correct chip ID found, device available
1896  -56	common/cmd_nand.c	Error reading Image Header on boot device
1897   56	common/cmd_nand.c	reading Image Header from NAND device OK
1898  -57	common/cmd_nand.c	Image header has bad magic number
1899   57	common/cmd_nand.c	Image header has correct magic number
1900  -58	common/cmd_nand.c	Error reading Image from NAND device
1901   58	common/cmd_nand.c	reading Image from NAND device OK
1902
1903  -60	common/env_common.c	Environment has a bad CRC, using default
1904
1905   64	net/eth.c		starting with Ethernet configuration.
1906  -64	net/eth.c		no Ethernet found.
1907   65	net/eth.c		Ethernet found.
1908
1909  -80	common/cmd_net.c	usage wrong
1910   80	common/cmd_net.c	before calling NetLoop()
1911  -81	common/cmd_net.c	some error in NetLoop() occurred
1912   81	common/cmd_net.c	NetLoop() back without error
1913  -82	common/cmd_net.c	size == 0 (File with size 0 loaded)
1914   82	common/cmd_net.c	trying automatic boot
1915   83	common/cmd_net.c	running autoscript
1916  -83	common/cmd_net.c	some error in automatic boot or autoscript
1917   84	common/cmd_net.c	end without errors
1918
1919FIT uImage format:
1920
1921  Arg	Where			When
1922  100	common/cmd_bootm.c	Kernel FIT Image has correct format
1923 -100	common/cmd_bootm.c	Kernel FIT Image has incorrect format
1924  101	common/cmd_bootm.c	No Kernel subimage unit name, using configuration
1925 -101	common/cmd_bootm.c	Can't get configuration for kernel subimage
1926  102	common/cmd_bootm.c	Kernel unit name specified
1927 -103	common/cmd_bootm.c	Can't get kernel subimage node offset
1928  103	common/cmd_bootm.c	Found configuration node
1929  104	common/cmd_bootm.c	Got kernel subimage node offset
1930 -104	common/cmd_bootm.c	Kernel subimage hash verification failed
1931  105	common/cmd_bootm.c	Kernel subimage hash verification OK
1932 -105	common/cmd_bootm.c	Kernel subimage is for unsupported architecture
1933  106	common/cmd_bootm.c	Architecture check OK
1934 -106	common/cmd_bootm.c	Kernel subimage has wrong type
1935  107	common/cmd_bootm.c	Kernel subimage type OK
1936 -107	common/cmd_bootm.c	Can't get kernel subimage data/size
1937  108	common/cmd_bootm.c	Got kernel subimage data/size
1938 -108	common/cmd_bootm.c	Wrong image type (not legacy, FIT)
1939 -109	common/cmd_bootm.c	Can't get kernel subimage type
1940 -110	common/cmd_bootm.c	Can't get kernel subimage comp
1941 -111	common/cmd_bootm.c	Can't get kernel subimage os
1942 -112	common/cmd_bootm.c	Can't get kernel subimage load address
1943 -113	common/cmd_bootm.c	Image uncompress/copy overwrite error
1944
1945  120	common/image.c		Start initial ramdisk verification
1946 -120	common/image.c		Ramdisk FIT image has incorrect format
1947  121	common/image.c		Ramdisk FIT image has correct format
1948  122	common/image.c		No ramdisk subimage unit name, using configuration
1949 -122	common/image.c		Can't get configuration for ramdisk subimage
1950  123	common/image.c		Ramdisk unit name specified
1951 -124	common/image.c		Can't get ramdisk subimage node offset
1952  125	common/image.c		Got ramdisk subimage node offset
1953 -125	common/image.c		Ramdisk subimage hash verification failed
1954  126	common/image.c		Ramdisk subimage hash verification OK
1955 -126	common/image.c		Ramdisk subimage for unsupported architecture
1956  127	common/image.c		Architecture check OK
1957 -127	common/image.c		Can't get ramdisk subimage data/size
1958  128	common/image.c		Got ramdisk subimage data/size
1959  129	common/image.c		Can't get ramdisk load address
1960 -129	common/image.c		Got ramdisk load address
1961
1962 -130	common/cmd_doc.c	Incorrect FIT image format
1963  131	common/cmd_doc.c	FIT image format OK
1964
1965 -140	common/cmd_ide.c	Incorrect FIT image format
1966  141	common/cmd_ide.c	FIT image format OK
1967
1968 -150	common/cmd_nand.c	Incorrect FIT image format
1969  151	common/cmd_nand.c	FIT image format OK
1970
1971
1972Modem Support:
1973--------------
1974
1975[so far only for SMDK2400 and TRAB boards]
1976
1977- Modem support enable:
1978		CONFIG_MODEM_SUPPORT
1979
1980- RTS/CTS Flow control enable:
1981		CONFIG_HWFLOW
1982
1983- Modem debug support:
1984		CONFIG_MODEM_SUPPORT_DEBUG
1985
1986		Enables debugging stuff (char screen[1024], dbg())
1987		for modem support. Useful only with BDI2000.
1988
1989- Interrupt support (PPC):
1990
1991		There are common interrupt_init() and timer_interrupt()
1992		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1993		for CPU specific initialization. interrupt_init_cpu()
1994		should set decrementer_count to appropriate value. If
1995		CPU resets decrementer automatically after interrupt
1996		(ppc4xx) it should set decrementer_count to zero.
1997		timer_interrupt() calls timer_interrupt_cpu() for CPU
1998		specific handling. If board has watchdog / status_led
1999		/ other_activity_monitor it works automatically from
2000		general timer_interrupt().
2001
2002- General:
2003
2004		In the target system modem support is enabled when a
2005		specific key (key combination) is pressed during
2006		power-on. Otherwise U-Boot will boot normally
2007		(autoboot). The key_pressed() function is called from
2008		board_init(). Currently key_pressed() is a dummy
2009		function, returning 1 and thus enabling modem
2010		initialization.
2011
2012		If there are no modem init strings in the
2013		environment, U-Boot proceed to autoboot; the
2014		previous output (banner, info printfs) will be
2015		suppressed, though.
2016
2017		See also: doc/README.Modem
2018
2019
2020Configuration Settings:
2021-----------------------
2022
2023- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2024		undefine this when you're short of memory.
2025
2026- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
2027		prompt for user input.
2028
2029- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console
2030
2031- CONFIG_SYS_PBSIZE:	Buffer size for Console output
2032
2033- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands
2034
2035- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2036		the application (usually a Linux kernel) when it is
2037		booted
2038
2039- CONFIG_SYS_BAUDRATE_TABLE:
2040		List of legal baudrate settings for this board.
2041
2042- CONFIG_SYS_CONSOLE_INFO_QUIET
2043		Suppress display of console information at boot.
2044
2045- CONFIG_SYS_CONSOLE_IS_IN_ENV
2046		If the board specific function
2047			extern int overwrite_console (void);
2048		returns 1, the stdin, stderr and stdout are switched to the
2049		serial port, else the settings in the environment are used.
2050
2051- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2052		Enable the call to overwrite_console().
2053
2054- CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2055		Enable overwrite of previous console environment settings.
2056
2057- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2058		Begin and End addresses of the area used by the
2059		simple memory test.
2060
2061- CONFIG_SYS_ALT_MEMTEST:
2062		Enable an alternate, more extensive memory test.
2063
2064- CONFIG_SYS_MEMTEST_SCRATCH:
2065		Scratch address used by the alternate memory test
2066		You only need to set this if address zero isn't writeable
2067
2068- CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2069		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2070		this specified memory area will get subtracted from the top
2071		(end) of RAM and won't get "touched" at all by U-Boot. By
2072		fixing up gd->ram_size the Linux kernel should gets passed
2073		the now "corrected" memory size and won't touch it either.
2074		This should work for arch/ppc and arch/powerpc. Only Linux
2075		board ports in arch/powerpc with bootwrapper support that
2076		recalculate the memory size from the SDRAM controller setup
2077		will have to get fixed in Linux additionally.
2078
2079		This option can be used as a workaround for the 440EPx/GRx
2080		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2081		be touched.
2082
2083		WARNING: Please make sure that this value is a multiple of
2084		the Linux page size (normally 4k). If this is not the case,
2085		then the end address of the Linux memory will be located at a
2086		non page size aligned address and this could cause major
2087		problems.
2088
2089- CONFIG_SYS_TFTP_LOADADDR:
2090		Default load address for network file downloads
2091
2092- CONFIG_SYS_LOADS_BAUD_CHANGE:
2093		Enable temporary baudrate change while serial download
2094
2095- CONFIG_SYS_SDRAM_BASE:
2096		Physical start address of SDRAM. _Must_ be 0 here.
2097
2098- CONFIG_SYS_MBIO_BASE:
2099		Physical start address of Motherboard I/O (if using a
2100		Cogent motherboard)
2101
2102- CONFIG_SYS_FLASH_BASE:
2103		Physical start address of Flash memory.
2104
2105- CONFIG_SYS_MONITOR_BASE:
2106		Physical start address of boot monitor code (set by
2107		make config files to be same as the text base address
2108		(TEXT_BASE) used when linking) - same as
2109		CONFIG_SYS_FLASH_BASE when booting from flash.
2110
2111- CONFIG_SYS_MONITOR_LEN:
2112		Size of memory reserved for monitor code, used to
2113		determine _at_compile_time_ (!) if the environment is
2114		embedded within the U-Boot image, or in a separate
2115		flash sector.
2116
2117- CONFIG_SYS_MALLOC_LEN:
2118		Size of DRAM reserved for malloc() use.
2119
2120- CONFIG_SYS_BOOTM_LEN:
2121		Normally compressed uImages are limited to an
2122		uncompressed size of 8 MBytes. If this is not enough,
2123		you can define CONFIG_SYS_BOOTM_LEN in your board config file
2124		to adjust this setting to your needs.
2125
2126- CONFIG_SYS_BOOTMAPSZ:
2127		Maximum size of memory mapped by the startup code of
2128		the Linux kernel; all data that must be processed by
2129		the Linux kernel (bd_info, boot arguments, FDT blob if
2130		used) must be put below this limit, unless "bootm_low"
2131		enviroment variable is defined and non-zero. In such case
2132		all data for the Linux kernel must be between "bootm_low"
2133		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
2134
2135- CONFIG_SYS_MAX_FLASH_BANKS:
2136		Max number of Flash memory banks
2137
2138- CONFIG_SYS_MAX_FLASH_SECT:
2139		Max number of sectors on a Flash chip
2140
2141- CONFIG_SYS_FLASH_ERASE_TOUT:
2142		Timeout for Flash erase operations (in ms)
2143
2144- CONFIG_SYS_FLASH_WRITE_TOUT:
2145		Timeout for Flash write operations (in ms)
2146
2147- CONFIG_SYS_FLASH_LOCK_TOUT
2148		Timeout for Flash set sector lock bit operation (in ms)
2149
2150- CONFIG_SYS_FLASH_UNLOCK_TOUT
2151		Timeout for Flash clear lock bits operation (in ms)
2152
2153- CONFIG_SYS_FLASH_PROTECTION
2154		If defined, hardware flash sectors protection is used
2155		instead of U-Boot software protection.
2156
2157- CONFIG_SYS_DIRECT_FLASH_TFTP:
2158
2159		Enable TFTP transfers directly to flash memory;
2160		without this option such a download has to be
2161		performed in two steps: (1) download to RAM, and (2)
2162		copy from RAM to flash.
2163
2164		The two-step approach is usually more reliable, since
2165		you can check if the download worked before you erase
2166		the flash, but in some situations (when system RAM is
2167		too limited to allow for a temporary copy of the
2168		downloaded image) this option may be very useful.
2169
2170- CONFIG_SYS_FLASH_CFI:
2171		Define if the flash driver uses extra elements in the
2172		common flash structure for storing flash geometry.
2173
2174- CONFIG_FLASH_CFI_DRIVER
2175		This option also enables the building of the cfi_flash driver
2176		in the drivers directory
2177
2178- CONFIG_FLASH_CFI_MTD
2179		This option enables the building of the cfi_mtd driver
2180		in the drivers directory. The driver exports CFI flash
2181		to the MTD layer.
2182
2183- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2184		Use buffered writes to flash.
2185
2186- CONFIG_FLASH_SPANSION_S29WS_N
2187		s29ws-n MirrorBit flash has non-standard addresses for buffered
2188		write commands.
2189
2190- CONFIG_SYS_FLASH_QUIET_TEST
2191		If this option is defined, the common CFI flash doesn't
2192		print it's warning upon not recognized FLASH banks. This
2193		is useful, if some of the configured banks are only
2194		optionally available.
2195
2196- CONFIG_FLASH_SHOW_PROGRESS
2197		If defined (must be an integer), print out countdown
2198		digits and dots.  Recommended value: 45 (9..1) for 80
2199		column displays, 15 (3..1) for 40 column displays.
2200
2201- CONFIG_SYS_RX_ETH_BUFFER:
2202		Defines the number of Ethernet receive buffers. On some
2203		Ethernet controllers it is recommended to set this value
2204		to 8 or even higher (EEPRO100 or 405 EMAC), since all
2205		buffers can be full shortly after enabling the interface
2206		on high Ethernet traffic.
2207		Defaults to 4 if not defined.
2208
2209The following definitions that deal with the placement and management
2210of environment data (variable area); in general, we support the
2211following configurations:
2212
2213- CONFIG_ENV_IS_IN_FLASH:
2214
2215	Define this if the environment is in flash memory.
2216
2217	a) The environment occupies one whole flash sector, which is
2218	   "embedded" in the text segment with the U-Boot code. This
2219	   happens usually with "bottom boot sector" or "top boot
2220	   sector" type flash chips, which have several smaller
2221	   sectors at the start or the end. For instance, such a
2222	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2223	   such a case you would place the environment in one of the
2224	   4 kB sectors - with U-Boot code before and after it. With
2225	   "top boot sector" type flash chips, you would put the
2226	   environment in one of the last sectors, leaving a gap
2227	   between U-Boot and the environment.
2228
2229	- CONFIG_ENV_OFFSET:
2230
2231	   Offset of environment data (variable area) to the
2232	   beginning of flash memory; for instance, with bottom boot
2233	   type flash chips the second sector can be used: the offset
2234	   for this sector is given here.
2235
2236	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2237
2238	- CONFIG_ENV_ADDR:
2239
2240	   This is just another way to specify the start address of
2241	   the flash sector containing the environment (instead of
2242	   CONFIG_ENV_OFFSET).
2243
2244	- CONFIG_ENV_SECT_SIZE:
2245
2246	   Size of the sector containing the environment.
2247
2248
2249	b) Sometimes flash chips have few, equal sized, BIG sectors.
2250	   In such a case you don't want to spend a whole sector for
2251	   the environment.
2252
2253	- CONFIG_ENV_SIZE:
2254
2255	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2256	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2257	   of this flash sector for the environment. This saves
2258	   memory for the RAM copy of the environment.
2259
2260	   It may also save flash memory if you decide to use this
2261	   when your environment is "embedded" within U-Boot code,
2262	   since then the remainder of the flash sector could be used
2263	   for U-Boot code. It should be pointed out that this is
2264	   STRONGLY DISCOURAGED from a robustness point of view:
2265	   updating the environment in flash makes it always
2266	   necessary to erase the WHOLE sector. If something goes
2267	   wrong before the contents has been restored from a copy in
2268	   RAM, your target system will be dead.
2269
2270	- CONFIG_ENV_ADDR_REDUND
2271	  CONFIG_ENV_SIZE_REDUND
2272
2273	   These settings describe a second storage area used to hold
2274	   a redundant copy of the environment data, so that there is
2275	   a valid backup copy in case there is a power failure during
2276	   a "saveenv" operation.
2277
2278BE CAREFUL! Any changes to the flash layout, and some changes to the
2279source code will make it necessary to adapt <board>/u-boot.lds*
2280accordingly!
2281
2282
2283- CONFIG_ENV_IS_IN_NVRAM:
2284
2285	Define this if you have some non-volatile memory device
2286	(NVRAM, battery buffered SRAM) which you want to use for the
2287	environment.
2288
2289	- CONFIG_ENV_ADDR:
2290	- CONFIG_ENV_SIZE:
2291
2292	  These two #defines are used to determine the memory area you
2293	  want to use for environment. It is assumed that this memory
2294	  can just be read and written to, without any special
2295	  provision.
2296
2297BE CAREFUL! The first access to the environment happens quite early
2298in U-Boot initalization (when we try to get the setting of for the
2299console baudrate). You *MUST* have mapped your NVRAM area then, or
2300U-Boot will hang.
2301
2302Please note that even with NVRAM we still use a copy of the
2303environment in RAM: we could work on NVRAM directly, but we want to
2304keep settings there always unmodified except somebody uses "saveenv"
2305to save the current settings.
2306
2307
2308- CONFIG_ENV_IS_IN_EEPROM:
2309
2310	Use this if you have an EEPROM or similar serial access
2311	device and a driver for it.
2312
2313	- CONFIG_ENV_OFFSET:
2314	- CONFIG_ENV_SIZE:
2315
2316	  These two #defines specify the offset and size of the
2317	  environment area within the total memory of your EEPROM.
2318
2319	- CONFIG_SYS_I2C_EEPROM_ADDR:
2320	  If defined, specified the chip address of the EEPROM device.
2321	  The default address is zero.
2322
2323	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2324	  If defined, the number of bits used to address bytes in a
2325	  single page in the EEPROM device.  A 64 byte page, for example
2326	  would require six bits.
2327
2328	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2329	  If defined, the number of milliseconds to delay between
2330	  page writes.	The default is zero milliseconds.
2331
2332	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2333	  The length in bytes of the EEPROM memory array address.  Note
2334	  that this is NOT the chip address length!
2335
2336	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2337	  EEPROM chips that implement "address overflow" are ones
2338	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2339	  address and the extra bits end up in the "chip address" bit
2340	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2341	  byte chips.
2342
2343	  Note that we consider the length of the address field to
2344	  still be one byte because the extra address bits are hidden
2345	  in the chip address.
2346
2347	- CONFIG_SYS_EEPROM_SIZE:
2348	  The size in bytes of the EEPROM device.
2349
2350
2351- CONFIG_ENV_IS_IN_DATAFLASH:
2352
2353	Define this if you have a DataFlash memory device which you
2354	want to use for the environment.
2355
2356	- CONFIG_ENV_OFFSET:
2357	- CONFIG_ENV_ADDR:
2358	- CONFIG_ENV_SIZE:
2359
2360	  These three #defines specify the offset and size of the
2361	  environment area within the total memory of your DataFlash placed
2362	  at the specified address.
2363
2364- CONFIG_ENV_IS_IN_NAND:
2365
2366	Define this if you have a NAND device which you want to use
2367	for the environment.
2368
2369	- CONFIG_ENV_OFFSET:
2370	- CONFIG_ENV_SIZE:
2371
2372	  These two #defines specify the offset and size of the environment
2373	  area within the first NAND device.
2374
2375	- CONFIG_ENV_OFFSET_REDUND
2376
2377	  This setting describes a second storage area of CONFIG_ENV_SIZE
2378	  size used to hold a redundant copy of the environment data,
2379	  so that there is a valid backup copy in case there is a
2380	  power failure during a "saveenv" operation.
2381
2382	Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2383	to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2384	the NAND devices block size.
2385
2386- CONFIG_SYS_SPI_INIT_OFFSET
2387
2388	Defines offset to the initial SPI buffer area in DPRAM. The
2389	area is used at an early stage (ROM part) if the environment
2390	is configured to reside in the SPI EEPROM: We need a 520 byte
2391	scratch DPRAM area. It is used between the two initialization
2392	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2393	to be a good choice since it makes it far enough from the
2394	start of the data area as well as from the stack pointer.
2395
2396Please note that the environment is read-only until the monitor
2397has been relocated to RAM and a RAM copy of the environment has been
2398created; also, when using EEPROM you will have to use getenv_r()
2399until then to read environment variables.
2400
2401The environment is protected by a CRC32 checksum. Before the monitor
2402is relocated into RAM, as a result of a bad CRC you will be working
2403with the compiled-in default environment - *silently*!!! [This is
2404necessary, because the first environment variable we need is the
2405"baudrate" setting for the console - if we have a bad CRC, we don't
2406have any device yet where we could complain.]
2407
2408Note: once the monitor has been relocated, then it will complain if
2409the default environment is used; a new CRC is computed as soon as you
2410use the "saveenv" command to store a valid environment.
2411
2412- CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2413		Echo the inverted Ethernet link state to the fault LED.
2414
2415		Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2416		      also needs to be defined.
2417
2418- CONFIG_SYS_FAULT_MII_ADDR:
2419		MII address of the PHY to check for the Ethernet link state.
2420
2421- CONFIG_SYS_64BIT_VSPRINTF:
2422		Makes vsprintf (and all *printf functions) support printing
2423		of 64bit values by using the L quantifier
2424
2425- CONFIG_SYS_64BIT_STRTOUL:
2426		Adds simple_strtoull that returns a 64bit value
2427
2428Low Level (hardware related) configuration options:
2429---------------------------------------------------
2430
2431- CONFIG_SYS_CACHELINE_SIZE:
2432		Cache Line Size of the CPU.
2433
2434- CONFIG_SYS_DEFAULT_IMMR:
2435		Default address of the IMMR after system reset.
2436
2437		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2438		and RPXsuper) to be able to adjust the position of
2439		the IMMR register after a reset.
2440
2441- Floppy Disk Support:
2442		CONFIG_SYS_FDC_DRIVE_NUMBER
2443
2444		the default drive number (default value 0)
2445
2446		CONFIG_SYS_ISA_IO_STRIDE
2447
2448		defines the spacing between FDC chipset registers
2449		(default value 1)
2450
2451		CONFIG_SYS_ISA_IO_OFFSET
2452
2453		defines the offset of register from address. It
2454		depends on which part of the data bus is connected to
2455		the FDC chipset. (default value 0)
2456
2457		If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2458		CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2459		default value.
2460
2461		if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2462		fdc_hw_init() is called at the beginning of the FDC
2463		setup. fdc_hw_init() must be provided by the board
2464		source code. It is used to make hardware dependant
2465		initializations.
2466
2467- CONFIG_SYS_IMMR:	Physical address of the Internal Memory.
2468		DO NOT CHANGE unless you know exactly what you're
2469		doing! (11-4) [MPC8xx/82xx systems only]
2470
2471- CONFIG_SYS_INIT_RAM_ADDR:
2472
2473		Start address of memory area that can be used for
2474		initial data and stack; please note that this must be
2475		writable memory that is working WITHOUT special
2476		initialization, i. e. you CANNOT use normal RAM which
2477		will become available only after programming the
2478		memory controller and running certain initialization
2479		sequences.
2480
2481		U-Boot uses the following memory types:
2482		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2483		- MPC824X: data cache
2484		- PPC4xx:  data cache
2485
2486- CONFIG_SYS_GBL_DATA_OFFSET:
2487
2488		Offset of the initial data structure in the memory
2489		area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2490		CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2491		data is located at the end of the available space
2492		(sometimes written as (CONFIG_SYS_INIT_RAM_END -
2493		CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
2494		below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2495		CONFIG_SYS_GBL_DATA_OFFSET) downward.
2496
2497	Note:
2498		On the MPC824X (or other systems that use the data
2499		cache for initial memory) the address chosen for
2500		CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2501		point to an otherwise UNUSED address space between
2502		the top of RAM and the start of the PCI space.
2503
2504- CONFIG_SYS_SIUMCR:	SIU Module Configuration (11-6)
2505
2506- CONFIG_SYS_SYPCR:	System Protection Control (11-9)
2507
2508- CONFIG_SYS_TBSCR:	Time Base Status and Control (11-26)
2509
2510- CONFIG_SYS_PISCR:	Periodic Interrupt Status and Control (11-31)
2511
2512- CONFIG_SYS_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
2513
2514- CONFIG_SYS_SCCR:	System Clock and reset Control Register (15-27)
2515
2516- CONFIG_SYS_OR_TIMING_SDRAM:
2517		SDRAM timing
2518
2519- CONFIG_SYS_MAMR_PTA:
2520		periodic timer for refresh
2521
2522- CONFIG_SYS_DER:	Debug Event Register (37-47)
2523
2524- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2525  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2526  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2527  CONFIG_SYS_BR1_PRELIM:
2528		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2529
2530- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2531  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2532  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2533		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2534
2535- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
2536  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
2537		Machine Mode Register and Memory Periodic Timer
2538		Prescaler definitions (SDRAM timing)
2539
2540- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
2541		enable I2C microcode relocation patch (MPC8xx);
2542		define relocation offset in DPRAM [DSP2]
2543
2544- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
2545		enable SMC microcode relocation patch (MPC8xx);
2546		define relocation offset in DPRAM [SMC1]
2547
2548- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
2549		enable SPI microcode relocation patch (MPC8xx);
2550		define relocation offset in DPRAM [SCC4]
2551
2552- CONFIG_SYS_USE_OSCCLK:
2553		Use OSCM clock mode on MBX8xx board. Be careful,
2554		wrong setting might damage your board. Read
2555		doc/README.MBX before setting this variable!
2556
2557- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2558		Offset of the bootmode word in DPRAM used by post
2559		(Power On Self Tests). This definition overrides
2560		#define'd default value in commproc.h resp.
2561		cpm_8260.h.
2562
2563- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
2564  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
2565  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
2566  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
2567  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2568  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
2569  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
2570  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
2571		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2572
2573- CONFIG_SPD_EEPROM
2574		Get DDR timing information from an I2C EEPROM. Common
2575		with pluggable memory modules such as SODIMMs
2576
2577  SPD_EEPROM_ADDRESS
2578		I2C address of the SPD EEPROM
2579
2580- CONFIG_SYS_SPD_BUS_NUM
2581		If SPD EEPROM is on an I2C bus other than the first
2582		one, specify here. Note that the value must resolve
2583		to something your driver can deal with.
2584
2585- CONFIG_SYS_83XX_DDR_USES_CS0
2586		Only for 83xx systems. If specified, then DDR should
2587		be configured using CS0 and CS1 instead of CS2 and CS3.
2588
2589- CONFIG_SYS_83XX_DDR_USES_CS0
2590		Only for 83xx systems. If specified, then DDR should
2591		be configured using CS0 and CS1 instead of CS2 and CS3.
2592
2593- CONFIG_ETHER_ON_FEC[12]
2594		Define to enable FEC[12] on a 8xx series processor.
2595
2596- CONFIG_FEC[12]_PHY
2597		Define to the hardcoded PHY address which corresponds
2598		to the given FEC; i. e.
2599			#define CONFIG_FEC1_PHY 4
2600		means that the PHY with address 4 is connected to FEC1
2601
2602		When set to -1, means to probe for first available.
2603
2604- CONFIG_FEC[12]_PHY_NORXERR
2605		The PHY does not have a RXERR line (RMII only).
2606		(so program the FEC to ignore it).
2607
2608- CONFIG_RMII
2609		Enable RMII mode for all FECs.
2610		Note that this is a global option, we can't
2611		have one FEC in standard MII mode and another in RMII mode.
2612
2613- CONFIG_CRC32_VERIFY
2614		Add a verify option to the crc32 command.
2615		The syntax is:
2616
2617		=> crc32 -v <address> <count> <crc32>
2618
2619		Where address/count indicate a memory area
2620		and crc32 is the correct crc32 which the
2621		area should have.
2622
2623- CONFIG_LOOPW
2624		Add the "loopw" memory command. This only takes effect if
2625		the memory commands are activated globally (CONFIG_CMD_MEM).
2626
2627- CONFIG_MX_CYCLIC
2628		Add the "mdc" and "mwc" memory commands. These are cyclic
2629		"md/mw" commands.
2630		Examples:
2631
2632		=> mdc.b 10 4 500
2633		This command will print 4 bytes (10,11,12,13) each 500 ms.
2634
2635		=> mwc.l 100 12345678 10
2636		This command will write 12345678 to address 100 all 10 ms.
2637
2638		This only takes effect if the memory commands are activated
2639		globally (CONFIG_CMD_MEM).
2640
2641- CONFIG_SKIP_LOWLEVEL_INIT
2642- CONFIG_SKIP_RELOCATE_UBOOT
2643
2644		[ARM only] If these variables are defined, then
2645		certain low level initializations (like setting up
2646		the memory controller) are omitted and/or U-Boot does
2647		not relocate itself into RAM.
2648		Normally these variables MUST NOT be defined. The
2649		only exception is when U-Boot is loaded (to RAM) by
2650		some other boot loader or by a debugger which
2651		performs these initializations itself.
2652
2653
2654Building the Software:
2655======================
2656
2657Building U-Boot has been tested in several native build environments
2658and in many different cross environments. Of course we cannot support
2659all possibly existing versions of cross development tools in all
2660(potentially obsolete) versions. In case of tool chain problems we
2661recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2662which is extensively used to build and test U-Boot.
2663
2664If you are not using a native environment, it is assumed that you
2665have GNU cross compiling tools available in your path. In this case,
2666you must set the environment variable CROSS_COMPILE in your shell.
2667Note that no changes to the Makefile or any other source files are
2668necessary. For example using the ELDK on a 4xx CPU, please enter:
2669
2670	$ CROSS_COMPILE=ppc_4xx-
2671	$ export CROSS_COMPILE
2672
2673U-Boot is intended to be simple to build. After installing the
2674sources you must configure U-Boot for one specific board type. This
2675is done by typing:
2676
2677	make NAME_config
2678
2679where "NAME_config" is the name of one of the existing configu-
2680rations; see the main Makefile for supported names.
2681
2682Note: for some board special configuration names may exist; check if
2683      additional information is available from the board vendor; for
2684      instance, the TQM823L systems are available without (standard)
2685      or with LCD support. You can select such additional "features"
2686      when choosing the configuration, i. e.
2687
2688      make TQM823L_config
2689	- will configure for a plain TQM823L, i. e. no LCD support
2690
2691      make TQM823L_LCD_config
2692	- will configure for a TQM823L with U-Boot console on LCD
2693
2694      etc.
2695
2696
2697Finally, type "make all", and you should get some working U-Boot
2698images ready for download to / installation on your system:
2699
2700- "u-boot.bin" is a raw binary image
2701- "u-boot" is an image in ELF binary format
2702- "u-boot.srec" is in Motorola S-Record format
2703
2704By default the build is performed locally and the objects are saved
2705in the source directory. One of the two methods can be used to change
2706this behavior and build U-Boot to some external directory:
2707
27081. Add O= to the make command line invocations:
2709
2710	make O=/tmp/build distclean
2711	make O=/tmp/build NAME_config
2712	make O=/tmp/build all
2713
27142. Set environment variable BUILD_DIR to point to the desired location:
2715
2716	export BUILD_DIR=/tmp/build
2717	make distclean
2718	make NAME_config
2719	make all
2720
2721Note that the command line "O=" setting overrides the BUILD_DIR environment
2722variable.
2723
2724
2725Please be aware that the Makefiles assume you are using GNU make, so
2726for instance on NetBSD you might need to use "gmake" instead of
2727native "make".
2728
2729
2730If the system board that you have is not listed, then you will need
2731to port U-Boot to your hardware platform. To do this, follow these
2732steps:
2733
27341.  Add a new configuration option for your board to the toplevel
2735    "Makefile" and to the "MAKEALL" script, using the existing
2736    entries as examples. Note that here and at many other places
2737    boards and other names are listed in alphabetical sort order. Please
2738    keep this order.
27392.  Create a new directory to hold your board specific code. Add any
2740    files you need. In your board directory, you will need at least
2741    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
27423.  Create a new configuration file "include/configs/<board>.h" for
2743    your board
27443.  If you're porting U-Boot to a new CPU, then also create a new
2745    directory to hold your CPU specific code. Add any files you need.
27464.  Run "make <board>_config" with your new name.
27475.  Type "make", and you should get a working "u-boot.srec" file
2748    to be installed on your target system.
27496.  Debug and solve any problems that might arise.
2750    [Of course, this last step is much harder than it sounds.]
2751
2752
2753Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2754==============================================================
2755
2756If you have modified U-Boot sources (for instance added a new board
2757or support for new devices, a new CPU, etc.) you are expected to
2758provide feedback to the other developers. The feedback normally takes
2759the form of a "patch", i. e. a context diff against a certain (latest
2760official or latest in the git repository) version of U-Boot sources.
2761
2762But before you submit such a patch, please verify that your modifi-
2763cation did not break existing code. At least make sure that *ALL* of
2764the supported boards compile WITHOUT ANY compiler warnings. To do so,
2765just run the "MAKEALL" script, which will configure and build U-Boot
2766for ALL supported system. Be warned, this will take a while. You can
2767select which (cross) compiler to use by passing a `CROSS_COMPILE'
2768environment variable to the script, i. e. to use the ELDK cross tools
2769you can type
2770
2771	CROSS_COMPILE=ppc_8xx- MAKEALL
2772
2773or to build on a native PowerPC system you can type
2774
2775	CROSS_COMPILE=' ' MAKEALL
2776
2777When using the MAKEALL script, the default behaviour is to build
2778U-Boot in the source directory. This location can be changed by
2779setting the BUILD_DIR environment variable. Also, for each target
2780built, the MAKEALL script saves two log files (<target>.ERR and
2781<target>.MAKEALL) in the <source dir>/LOG directory. This default
2782location can be changed by setting the MAKEALL_LOGDIR environment
2783variable. For example:
2784
2785	export BUILD_DIR=/tmp/build
2786	export MAKEALL_LOGDIR=/tmp/log
2787	CROSS_COMPILE=ppc_8xx- MAKEALL
2788
2789With the above settings build objects are saved in the /tmp/build,
2790log files are saved in the /tmp/log and the source tree remains clean
2791during the whole build process.
2792
2793
2794See also "U-Boot Porting Guide" below.
2795
2796
2797Monitor Commands - Overview:
2798============================
2799
2800go	- start application at address 'addr'
2801run	- run commands in an environment variable
2802bootm	- boot application image from memory
2803bootp	- boot image via network using BootP/TFTP protocol
2804tftpboot- boot image via network using TFTP protocol
2805	       and env variables "ipaddr" and "serverip"
2806	       (and eventually "gatewayip")
2807rarpboot- boot image via network using RARP/TFTP protocol
2808diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2809loads	- load S-Record file over serial line
2810loadb	- load binary file over serial line (kermit mode)
2811md	- memory display
2812mm	- memory modify (auto-incrementing)
2813nm	- memory modify (constant address)
2814mw	- memory write (fill)
2815cp	- memory copy
2816cmp	- memory compare
2817crc32	- checksum calculation
2818imd	- i2c memory display
2819imm	- i2c memory modify (auto-incrementing)
2820inm	- i2c memory modify (constant address)
2821imw	- i2c memory write (fill)
2822icrc32	- i2c checksum calculation
2823iprobe	- probe to discover valid I2C chip addresses
2824iloop	- infinite loop on address range
2825isdram	- print SDRAM configuration information
2826sspi	- SPI utility commands
2827base	- print or set address offset
2828printenv- print environment variables
2829setenv	- set environment variables
2830saveenv - save environment variables to persistent storage
2831protect - enable or disable FLASH write protection
2832erase	- erase FLASH memory
2833flinfo	- print FLASH memory information
2834bdinfo	- print Board Info structure
2835iminfo	- print header information for application image
2836coninfo - print console devices and informations
2837ide	- IDE sub-system
2838loop	- infinite loop on address range
2839loopw	- infinite write loop on address range
2840mtest	- simple RAM test
2841icache	- enable or disable instruction cache
2842dcache	- enable or disable data cache
2843reset	- Perform RESET of the CPU
2844echo	- echo args to console
2845version - print monitor version
2846help	- print online help
2847?	- alias for 'help'
2848
2849
2850Monitor Commands - Detailed Description:
2851========================================
2852
2853TODO.
2854
2855For now: just type "help <command>".
2856
2857
2858Environment Variables:
2859======================
2860
2861U-Boot supports user configuration using Environment Variables which
2862can be made persistent by saving to Flash memory.
2863
2864Environment Variables are set using "setenv", printed using
2865"printenv", and saved to Flash using "saveenv". Using "setenv"
2866without a value can be used to delete a variable from the
2867environment. As long as you don't save the environment you are
2868working with an in-memory copy. In case the Flash area containing the
2869environment is erased by accident, a default environment is provided.
2870
2871Some configuration options can be set using Environment Variables:
2872
2873  baudrate	- see CONFIG_BAUDRATE
2874
2875  bootdelay	- see CONFIG_BOOTDELAY
2876
2877  bootcmd	- see CONFIG_BOOTCOMMAND
2878
2879  bootargs	- Boot arguments when booting an RTOS image
2880
2881  bootfile	- Name of the image to load with TFTP
2882
2883  bootm_low	- Memory range available for image processing in the bootm
2884		  command can be restricted. This variable is given as
2885		  a hexadecimal number and defines lowest address allowed
2886		  for use by the bootm command. See also "bootm_size"
2887		  environment variable. Address defined by "bootm_low" is
2888		  also the base of the initial memory mapping for the Linux
2889		  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
2890
2891  bootm_size	- Memory range available for image processing in the bootm
2892		  command can be restricted. This variable is given as
2893		  a hexadecimal number and defines the size of the region
2894		  allowed for use by the bootm command. See also "bootm_low"
2895		  environment variable.
2896
2897  updatefile	- Location of the software update file on a TFTP server, used
2898		  by the automatic software update feature. Please refer to
2899		  documentation in doc/README.update for more details.
2900
2901  autoload	- if set to "no" (any string beginning with 'n'),
2902		  "bootp" will just load perform a lookup of the
2903		  configuration from the BOOTP server, but not try to
2904		  load any image using TFTP
2905
2906  autoscript	- if set to "yes" commands like "loadb", "loady",
2907		  "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2908		  to automatically run script images (by internally
2909		  calling "autoscript").
2910
2911  autoscript_uname - if script image is in a format (FIT) this
2912		     variable is used to get script subimage unit name.
2913
2914  autostart	- if set to "yes", an image loaded using the "bootp",
2915		  "rarpboot", "tftpboot" or "diskboot" commands will
2916		  be automatically started (by internally calling
2917		  "bootm")
2918
2919		  If set to "no", a standalone image passed to the
2920		  "bootm" command will be copied to the load address
2921		  (and eventually uncompressed), but NOT be started.
2922		  This can be used to load and uncompress arbitrary
2923		  data.
2924
2925  i2cfast	- (PPC405GP|PPC405EP only)
2926		  if set to 'y' configures Linux I2C driver for fast
2927		  mode (400kHZ). This environment variable is used in
2928		  initialization code. So, for changes to be effective
2929		  it must be saved and board must be reset.
2930
2931  initrd_high	- restrict positioning of initrd images:
2932		  If this variable is not set, initrd images will be
2933		  copied to the highest possible address in RAM; this
2934		  is usually what you want since it allows for
2935		  maximum initrd size. If for some reason you want to
2936		  make sure that the initrd image is loaded below the
2937		  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
2938		  variable to a value of "no" or "off" or "0".
2939		  Alternatively, you can set it to a maximum upper
2940		  address to use (U-Boot will still check that it
2941		  does not overwrite the U-Boot stack and data).
2942
2943		  For instance, when you have a system with 16 MB
2944		  RAM, and want to reserve 4 MB from use by Linux,
2945		  you can do this by adding "mem=12M" to the value of
2946		  the "bootargs" variable. However, now you must make
2947		  sure that the initrd image is placed in the first
2948		  12 MB as well - this can be done with
2949
2950		  setenv initrd_high 00c00000
2951
2952		  If you set initrd_high to 0xFFFFFFFF, this is an
2953		  indication to U-Boot that all addresses are legal
2954		  for the Linux kernel, including addresses in flash
2955		  memory. In this case U-Boot will NOT COPY the
2956		  ramdisk at all. This may be useful to reduce the
2957		  boot time on your system, but requires that this
2958		  feature is supported by your Linux kernel.
2959
2960  ipaddr	- IP address; needed for tftpboot command
2961
2962  loadaddr	- Default load address for commands like "bootp",
2963		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2964
2965  loads_echo	- see CONFIG_LOADS_ECHO
2966
2967  serverip	- TFTP server IP address; needed for tftpboot command
2968
2969  bootretry	- see CONFIG_BOOT_RETRY_TIME
2970
2971  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2972
2973  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2974
2975  ethprime	- When CONFIG_NET_MULTI is enabled controls which
2976		  interface is used first.
2977
2978  ethact	- When CONFIG_NET_MULTI is enabled controls which
2979		  interface is currently active. For example you
2980		  can do the following
2981
2982		  => setenv ethact FEC ETHERNET
2983		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2984		  => setenv ethact SCC ETHERNET
2985		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2986
2987  ethrotate	- When set to "no" U-Boot does not go through all
2988		  available network interfaces.
2989		  It just stays at the currently selected interface.
2990
2991   netretry	- When set to "no" each network operation will
2992		  either succeed or fail without retrying.
2993		  When set to "once" the network operation will
2994		  fail when all the available network interfaces
2995		  are tried once without success.
2996		  Useful on scripts which control the retry operation
2997		  themselves.
2998
2999  npe_ucode	- see CONFIG_IXP4XX_NPE_EXT_UCOD
3000		  if set load address for the NPE microcode
3001
3002  tftpsrcport	- If this is set, the value is used for TFTP's
3003		  UDP source port.
3004
3005  tftpdstport	- If this is set, the value is used for TFTP's UDP
3006		  destination port instead of the Well Know Port 69.
3007
3008   vlan		- When set to a value < 4095 the traffic over
3009		  Ethernet is encapsulated/received over 802.1q
3010		  VLAN tagged frames.
3011
3012The following environment variables may be used and automatically
3013updated by the network boot commands ("bootp" and "rarpboot"),
3014depending the information provided by your boot server:
3015
3016  bootfile	- see above
3017  dnsip		- IP address of your Domain Name Server
3018  dnsip2	- IP address of your secondary Domain Name Server
3019  gatewayip	- IP address of the Gateway (Router) to use
3020  hostname	- Target hostname
3021  ipaddr	- see above
3022  netmask	- Subnet Mask
3023  rootpath	- Pathname of the root filesystem on the NFS server
3024  serverip	- see above
3025
3026
3027There are two special Environment Variables:
3028
3029  serial#	- contains hardware identification information such
3030		  as type string and/or serial number
3031  ethaddr	- Ethernet address
3032
3033These variables can be set only once (usually during manufacturing of
3034the board). U-Boot refuses to delete or overwrite these variables
3035once they have been set once.
3036
3037
3038Further special Environment Variables:
3039
3040  ver		- Contains the U-Boot version string as printed
3041		  with the "version" command. This variable is
3042		  readonly (see CONFIG_VERSION_VARIABLE).
3043
3044
3045Please note that changes to some configuration parameters may take
3046only effect after the next boot (yes, that's just like Windoze :-).
3047
3048
3049Command Line Parsing:
3050=====================
3051
3052There are two different command line parsers available with U-Boot:
3053the old "simple" one, and the much more powerful "hush" shell:
3054
3055Old, simple command line parser:
3056--------------------------------
3057
3058- supports environment variables (through setenv / saveenv commands)
3059- several commands on one line, separated by ';'
3060- variable substitution using "... ${name} ..." syntax
3061- special characters ('$', ';') can be escaped by prefixing with '\',
3062  for example:
3063	setenv bootcmd bootm \${address}
3064- You can also escape text by enclosing in single apostrophes, for example:
3065	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3066
3067Hush shell:
3068-----------
3069
3070- similar to Bourne shell, with control structures like
3071  if...then...else...fi, for...do...done; while...do...done,
3072  until...do...done, ...
3073- supports environment ("global") variables (through setenv / saveenv
3074  commands) and local shell variables (through standard shell syntax
3075  "name=value"); only environment variables can be used with "run"
3076  command
3077
3078General rules:
3079--------------
3080
3081(1) If a command line (or an environment variable executed by a "run"
3082    command) contains several commands separated by semicolon, and
3083    one of these commands fails, then the remaining commands will be
3084    executed anyway.
3085
3086(2) If you execute several variables with one call to run (i. e.
3087    calling run with a list of variables as arguments), any failing
3088    command will cause "run" to terminate, i. e. the remaining
3089    variables are not executed.
3090
3091Note for Redundant Ethernet Interfaces:
3092=======================================
3093
3094Some boards come with redundant Ethernet interfaces; U-Boot supports
3095such configurations and is capable of automatic selection of a
3096"working" interface when needed. MAC assignment works as follows:
3097
3098Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3099MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3100"eth1addr" (=>eth1), "eth2addr", ...
3101
3102If the network interface stores some valid MAC address (for instance
3103in SROM), this is used as default address if there is NO correspon-
3104ding setting in the environment; if the corresponding environment
3105variable is set, this overrides the settings in the card; that means:
3106
3107o If the SROM has a valid MAC address, and there is no address in the
3108  environment, the SROM's address is used.
3109
3110o If there is no valid address in the SROM, and a definition in the
3111  environment exists, then the value from the environment variable is
3112  used.
3113
3114o If both the SROM and the environment contain a MAC address, and
3115  both addresses are the same, this MAC address is used.
3116
3117o If both the SROM and the environment contain a MAC address, and the
3118  addresses differ, the value from the environment is used and a
3119  warning is printed.
3120
3121o If neither SROM nor the environment contain a MAC address, an error
3122  is raised.
3123
3124
3125Image Formats:
3126==============
3127
3128U-Boot is capable of booting (and performing other auxiliary operations on)
3129images in two formats:
3130
3131New uImage format (FIT)
3132-----------------------
3133
3134Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3135to Flattened Device Tree). It allows the use of images with multiple
3136components (several kernels, ramdisks, etc.), with contents protected by
3137SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3138
3139
3140Old uImage format
3141-----------------
3142
3143Old image format is based on binary files which can be basically anything,
3144preceded by a special header; see the definitions in include/image.h for
3145details; basically, the header defines the following image properties:
3146
3147* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3148  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3149  LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3150  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3151  INTEGRITY).
3152* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3153  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3154  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3155* Compression Type (uncompressed, gzip, bzip2)
3156* Load Address
3157* Entry Point
3158* Image Name
3159* Image Timestamp
3160
3161The header is marked by a special Magic Number, and both the header
3162and the data portions of the image are secured against corruption by
3163CRC32 checksums.
3164
3165
3166Linux Support:
3167==============
3168
3169Although U-Boot should support any OS or standalone application
3170easily, the main focus has always been on Linux during the design of
3171U-Boot.
3172
3173U-Boot includes many features that so far have been part of some
3174special "boot loader" code within the Linux kernel. Also, any
3175"initrd" images to be used are no longer part of one big Linux image;
3176instead, kernel and "initrd" are separate images. This implementation
3177serves several purposes:
3178
3179- the same features can be used for other OS or standalone
3180  applications (for instance: using compressed images to reduce the
3181  Flash memory footprint)
3182
3183- it becomes much easier to port new Linux kernel versions because
3184  lots of low-level, hardware dependent stuff are done by U-Boot
3185
3186- the same Linux kernel image can now be used with different "initrd"
3187  images; of course this also means that different kernel images can
3188  be run with the same "initrd". This makes testing easier (you don't
3189  have to build a new "zImage.initrd" Linux image when you just
3190  change a file in your "initrd"). Also, a field-upgrade of the
3191  software is easier now.
3192
3193
3194Linux HOWTO:
3195============
3196
3197Porting Linux to U-Boot based systems:
3198---------------------------------------
3199
3200U-Boot cannot save you from doing all the necessary modifications to
3201configure the Linux device drivers for use with your target hardware
3202(no, we don't intend to provide a full virtual machine interface to
3203Linux :-).
3204
3205But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3206
3207Just make sure your machine specific header file (for instance
3208include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3209Information structure as we define in include/asm-<arch>/u-boot.h,
3210and make sure that your definition of IMAP_ADDR uses the same value
3211as your U-Boot configuration in CONFIG_SYS_IMMR.
3212
3213
3214Configuring the Linux kernel:
3215-----------------------------
3216
3217No specific requirements for U-Boot. Make sure you have some root
3218device (initial ramdisk, NFS) for your target system.
3219
3220
3221Building a Linux Image:
3222-----------------------
3223
3224With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3225not used. If you use recent kernel source, a new build target
3226"uImage" will exist which automatically builds an image usable by
3227U-Boot. Most older kernels also have support for a "pImage" target,
3228which was introduced for our predecessor project PPCBoot and uses a
3229100% compatible format.
3230
3231Example:
3232
3233	make TQM850L_config
3234	make oldconfig
3235	make dep
3236	make uImage
3237
3238The "uImage" build target uses a special tool (in 'tools/mkimage') to
3239encapsulate a compressed Linux kernel image with header	 information,
3240CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3241
3242* build a standard "vmlinux" kernel image (in ELF binary format):
3243
3244* convert the kernel into a raw binary image:
3245
3246	${CROSS_COMPILE}-objcopy -O binary \
3247				 -R .note -R .comment \
3248				 -S vmlinux linux.bin
3249
3250* compress the binary image:
3251
3252	gzip -9 linux.bin
3253
3254* package compressed binary image for U-Boot:
3255
3256	mkimage -A ppc -O linux -T kernel -C gzip \
3257		-a 0 -e 0 -n "Linux Kernel Image" \
3258		-d linux.bin.gz uImage
3259
3260
3261The "mkimage" tool can also be used to create ramdisk images for use
3262with U-Boot, either separated from the Linux kernel image, or
3263combined into one file. "mkimage" encapsulates the images with a 64
3264byte header containing information about target architecture,
3265operating system, image type, compression method, entry points, time
3266stamp, CRC32 checksums, etc.
3267
3268"mkimage" can be called in two ways: to verify existing images and
3269print the header information, or to build new images.
3270
3271In the first form (with "-l" option) mkimage lists the information
3272contained in the header of an existing U-Boot image; this includes
3273checksum verification:
3274
3275	tools/mkimage -l image
3276	  -l ==> list image header information
3277
3278The second form (with "-d" option) is used to build a U-Boot image
3279from a "data file" which is used as image payload:
3280
3281	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3282		      -n name -d data_file image
3283	  -A ==> set architecture to 'arch'
3284	  -O ==> set operating system to 'os'
3285	  -T ==> set image type to 'type'
3286	  -C ==> set compression type 'comp'
3287	  -a ==> set load address to 'addr' (hex)
3288	  -e ==> set entry point to 'ep' (hex)
3289	  -n ==> set image name to 'name'
3290	  -d ==> use image data from 'datafile'
3291
3292Right now, all Linux kernels for PowerPC systems use the same load
3293address (0x00000000), but the entry point address depends on the
3294kernel version:
3295
3296- 2.2.x kernels have the entry point at 0x0000000C,
3297- 2.3.x and later kernels have the entry point at 0x00000000.
3298
3299So a typical call to build a U-Boot image would read:
3300
3301	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3302	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3303	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3304	> examples/uImage.TQM850L
3305	Image Name:   2.4.4 kernel for TQM850L
3306	Created:      Wed Jul 19 02:34:59 2000
3307	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3308	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3309	Load Address: 0x00000000
3310	Entry Point:  0x00000000
3311
3312To verify the contents of the image (or check for corruption):
3313
3314	-> tools/mkimage -l examples/uImage.TQM850L
3315	Image Name:   2.4.4 kernel for TQM850L
3316	Created:      Wed Jul 19 02:34:59 2000
3317	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
3318	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
3319	Load Address: 0x00000000
3320	Entry Point:  0x00000000
3321
3322NOTE: for embedded systems where boot time is critical you can trade
3323speed for memory and install an UNCOMPRESSED image instead: this
3324needs more space in Flash, but boots much faster since it does not
3325need to be uncompressed:
3326
3327	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3328	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3329	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3330	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3331	> examples/uImage.TQM850L-uncompressed
3332	Image Name:   2.4.4 kernel for TQM850L
3333	Created:      Wed Jul 19 02:34:59 2000
3334	Image Type:   PowerPC Linux Kernel Image (uncompressed)
3335	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
3336	Load Address: 0x00000000
3337	Entry Point:  0x00000000
3338
3339
3340Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3341when your kernel is intended to use an initial ramdisk:
3342
3343	-> tools/mkimage -n 'Simple Ramdisk Image' \
3344	> -A ppc -O linux -T ramdisk -C gzip \
3345	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3346	Image Name:   Simple Ramdisk Image
3347	Created:      Wed Jan 12 14:01:50 2000
3348	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
3349	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
3350	Load Address: 0x00000000
3351	Entry Point:  0x00000000
3352
3353
3354Installing a Linux Image:
3355-------------------------
3356
3357To downloading a U-Boot image over the serial (console) interface,
3358you must convert the image to S-Record format:
3359
3360	objcopy -I binary -O srec examples/image examples/image.srec
3361
3362The 'objcopy' does not understand the information in the U-Boot
3363image header, so the resulting S-Record file will be relative to
3364address 0x00000000. To load it to a given address, you need to
3365specify the target address as 'offset' parameter with the 'loads'
3366command.
3367
3368Example: install the image to address 0x40100000 (which on the
3369TQM8xxL is in the first Flash bank):
3370
3371	=> erase 40100000 401FFFFF
3372
3373	.......... done
3374	Erased 8 sectors
3375
3376	=> loads 40100000
3377	## Ready for S-Record download ...
3378	~>examples/image.srec
3379	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3380	...
3381	15989 15990 15991 15992
3382	[file transfer complete]
3383	[connected]
3384	## Start Addr = 0x00000000
3385
3386
3387You can check the success of the download using the 'iminfo' command;
3388this includes a checksum verification so you can be sure no data
3389corruption happened:
3390
3391	=> imi 40100000
3392
3393	## Checking Image at 40100000 ...
3394	   Image Name:	 2.2.13 for initrd on TQM850L
3395	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3396	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3397	   Load Address: 00000000
3398	   Entry Point:	 0000000c
3399	   Verifying Checksum ... OK
3400
3401
3402Boot Linux:
3403-----------
3404
3405The "bootm" command is used to boot an application that is stored in
3406memory (RAM or Flash). In case of a Linux kernel image, the contents
3407of the "bootargs" environment variable is passed to the kernel as
3408parameters. You can check and modify this variable using the
3409"printenv" and "setenv" commands:
3410
3411
3412	=> printenv bootargs
3413	bootargs=root=/dev/ram
3414
3415	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3416
3417	=> printenv bootargs
3418	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3419
3420	=> bootm 40020000
3421	## Booting Linux kernel at 40020000 ...
3422	   Image Name:	 2.2.13 for NFS on TQM850L
3423	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3424	   Data Size:	 381681 Bytes = 372 kB = 0 MB
3425	   Load Address: 00000000
3426	   Entry Point:	 0000000c
3427	   Verifying Checksum ... OK
3428	   Uncompressing Kernel Image ... OK
3429	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
3430	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3431	time_init: decrementer frequency = 187500000/60
3432	Calibrating delay loop... 49.77 BogoMIPS
3433	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3434	...
3435
3436If you want to boot a Linux kernel with initial RAM disk, you pass
3437the memory addresses of both the kernel and the initrd image (PPBCOOT
3438format!) to the "bootm" command:
3439
3440	=> imi 40100000 40200000
3441
3442	## Checking Image at 40100000 ...
3443	   Image Name:	 2.2.13 for initrd on TQM850L
3444	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3445	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3446	   Load Address: 00000000
3447	   Entry Point:	 0000000c
3448	   Verifying Checksum ... OK
3449
3450	## Checking Image at 40200000 ...
3451	   Image Name:	 Simple Ramdisk Image
3452	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3453	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3454	   Load Address: 00000000
3455	   Entry Point:	 00000000
3456	   Verifying Checksum ... OK
3457
3458	=> bootm 40100000 40200000
3459	## Booting Linux kernel at 40100000 ...
3460	   Image Name:	 2.2.13 for initrd on TQM850L
3461	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3462	   Data Size:	 335725 Bytes = 327 kB = 0 MB
3463	   Load Address: 00000000
3464	   Entry Point:	 0000000c
3465	   Verifying Checksum ... OK
3466	   Uncompressing Kernel Image ... OK
3467	## Loading RAMDisk Image at 40200000 ...
3468	   Image Name:	 Simple Ramdisk Image
3469	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
3470	   Data Size:	 566530 Bytes = 553 kB = 0 MB
3471	   Load Address: 00000000
3472	   Entry Point:	 00000000
3473	   Verifying Checksum ... OK
3474	   Loading Ramdisk ... OK
3475	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
3476	Boot arguments: root=/dev/ram
3477	time_init: decrementer frequency = 187500000/60
3478	Calibrating delay loop... 49.77 BogoMIPS
3479	...
3480	RAMDISK: Compressed image found at block 0
3481	VFS: Mounted root (ext2 filesystem).
3482
3483	bash#
3484
3485Boot Linux and pass a flat device tree:
3486-----------
3487
3488First, U-Boot must be compiled with the appropriate defines. See the section
3489titled "Linux Kernel Interface" above for a more in depth explanation. The
3490following is an example of how to start a kernel and pass an updated
3491flat device tree:
3492
3493=> print oftaddr
3494oftaddr=0x300000
3495=> print oft
3496oft=oftrees/mpc8540ads.dtb
3497=> tftp $oftaddr $oft
3498Speed: 1000, full duplex
3499Using TSEC0 device
3500TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3501Filename 'oftrees/mpc8540ads.dtb'.
3502Load address: 0x300000
3503Loading: #
3504done
3505Bytes transferred = 4106 (100a hex)
3506=> tftp $loadaddr $bootfile
3507Speed: 1000, full duplex
3508Using TSEC0 device
3509TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3510Filename 'uImage'.
3511Load address: 0x200000
3512Loading:############
3513done
3514Bytes transferred = 1029407 (fb51f hex)
3515=> print loadaddr
3516loadaddr=200000
3517=> print oftaddr
3518oftaddr=0x300000
3519=> bootm $loadaddr - $oftaddr
3520## Booting image at 00200000 ...
3521   Image Name:	 Linux-2.6.17-dirty
3522   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
3523   Data Size:	 1029343 Bytes = 1005.2 kB
3524   Load Address: 00000000
3525   Entry Point:	 00000000
3526   Verifying Checksum ... OK
3527   Uncompressing Kernel Image ... OK
3528Booting using flat device tree at 0x300000
3529Using MPC85xx ADS machine description
3530Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3531[snip]
3532
3533
3534More About U-Boot Image Types:
3535------------------------------
3536
3537U-Boot supports the following image types:
3538
3539   "Standalone Programs" are directly runnable in the environment
3540	provided by U-Boot; it is expected that (if they behave
3541	well) you can continue to work in U-Boot after return from
3542	the Standalone Program.
3543   "OS Kernel Images" are usually images of some Embedded OS which
3544	will take over control completely. Usually these programs
3545	will install their own set of exception handlers, device
3546	drivers, set up the MMU, etc. - this means, that you cannot
3547	expect to re-enter U-Boot except by resetting the CPU.
3548   "RAMDisk Images" are more or less just data blocks, and their
3549	parameters (address, size) are passed to an OS kernel that is
3550	being started.
3551   "Multi-File Images" contain several images, typically an OS
3552	(Linux) kernel image and one or more data images like
3553	RAMDisks. This construct is useful for instance when you want
3554	to boot over the network using BOOTP etc., where the boot
3555	server provides just a single image file, but you want to get
3556	for instance an OS kernel and a RAMDisk image.
3557
3558	"Multi-File Images" start with a list of image sizes, each
3559	image size (in bytes) specified by an "uint32_t" in network
3560	byte order. This list is terminated by an "(uint32_t)0".
3561	Immediately after the terminating 0 follow the images, one by
3562	one, all aligned on "uint32_t" boundaries (size rounded up to
3563	a multiple of 4 bytes).
3564
3565   "Firmware Images" are binary images containing firmware (like
3566	U-Boot or FPGA images) which usually will be programmed to
3567	flash memory.
3568
3569   "Script files" are command sequences that will be executed by
3570	U-Boot's command interpreter; this feature is especially
3571	useful when you configure U-Boot to use a real shell (hush)
3572	as command interpreter.
3573
3574
3575Standalone HOWTO:
3576=================
3577
3578One of the features of U-Boot is that you can dynamically load and
3579run "standalone" applications, which can use some resources of
3580U-Boot like console I/O functions or interrupt services.
3581
3582Two simple examples are included with the sources:
3583
3584"Hello World" Demo:
3585-------------------
3586
3587'examples/hello_world.c' contains a small "Hello World" Demo
3588application; it is automatically compiled when you build U-Boot.
3589It's configured to run at address 0x00040004, so you can play with it
3590like that:
3591
3592	=> loads
3593	## Ready for S-Record download ...
3594	~>examples/hello_world.srec
3595	1 2 3 4 5 6 7 8 9 10 11 ...
3596	[file transfer complete]
3597	[connected]
3598	## Start Addr = 0x00040004
3599
3600	=> go 40004 Hello World! This is a test.
3601	## Starting application at 0x00040004 ...
3602	Hello World
3603	argc = 7
3604	argv[0] = "40004"
3605	argv[1] = "Hello"
3606	argv[2] = "World!"
3607	argv[3] = "This"
3608	argv[4] = "is"
3609	argv[5] = "a"
3610	argv[6] = "test."
3611	argv[7] = "<NULL>"
3612	Hit any key to exit ...
3613
3614	## Application terminated, rc = 0x0
3615
3616Another example, which demonstrates how to register a CPM interrupt
3617handler with the U-Boot code, can be found in 'examples/timer.c'.
3618Here, a CPM timer is set up to generate an interrupt every second.
3619The interrupt service routine is trivial, just printing a '.'
3620character, but this is just a demo program. The application can be
3621controlled by the following keys:
3622
3623	? - print current values og the CPM Timer registers
3624	b - enable interrupts and start timer
3625	e - stop timer and disable interrupts
3626	q - quit application
3627
3628	=> loads
3629	## Ready for S-Record download ...
3630	~>examples/timer.srec
3631	1 2 3 4 5 6 7 8 9 10 11 ...
3632	[file transfer complete]
3633	[connected]
3634	## Start Addr = 0x00040004
3635
3636	=> go 40004
3637	## Starting application at 0x00040004 ...
3638	TIMERS=0xfff00980
3639	Using timer 1
3640	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3641
3642Hit 'b':
3643	[q, b, e, ?] Set interval 1000000 us
3644	Enabling timer
3645Hit '?':
3646	[q, b, e, ?] ........
3647	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3648Hit '?':
3649	[q, b, e, ?] .
3650	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3651Hit '?':
3652	[q, b, e, ?] .
3653	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3654Hit '?':
3655	[q, b, e, ?] .
3656	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3657Hit 'e':
3658	[q, b, e, ?] ...Stopping timer
3659Hit 'q':
3660	[q, b, e, ?] ## Application terminated, rc = 0x0
3661
3662
3663Minicom warning:
3664================
3665
3666Over time, many people have reported problems when trying to use the
3667"minicom" terminal emulation program for serial download. I (wd)
3668consider minicom to be broken, and recommend not to use it. Under
3669Unix, I recommend to use C-Kermit for general purpose use (and
3670especially for kermit binary protocol download ("loadb" command), and
3671use "cu" for S-Record download ("loads" command).
3672
3673Nevertheless, if you absolutely want to use it try adding this
3674configuration to your "File transfer protocols" section:
3675
3676	   Name	   Program			Name U/D FullScr IO-Red. Multi
3677	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
3678	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
3679
3680
3681NetBSD Notes:
3682=============
3683
3684Starting at version 0.9.2, U-Boot supports NetBSD both as host
3685(build U-Boot) and target system (boots NetBSD/mpc8xx).
3686
3687Building requires a cross environment; it is known to work on
3688NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3689need gmake since the Makefiles are not compatible with BSD make).
3690Note that the cross-powerpc package does not install include files;
3691attempting to build U-Boot will fail because <machine/ansi.h> is
3692missing.  This file has to be installed and patched manually:
3693
3694	# cd /usr/pkg/cross/powerpc-netbsd/include
3695	# mkdir powerpc
3696	# ln -s powerpc machine
3697	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3698	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
3699
3700Native builds *don't* work due to incompatibilities between native
3701and U-Boot include files.
3702
3703Booting assumes that (the first part of) the image booted is a
3704stage-2 loader which in turn loads and then invokes the kernel
3705proper. Loader sources will eventually appear in the NetBSD source
3706tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3707meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3708
3709
3710Implementation Internals:
3711=========================
3712
3713The following is not intended to be a complete description of every
3714implementation detail. However, it should help to understand the
3715inner workings of U-Boot and make it easier to port it to custom
3716hardware.
3717
3718
3719Initial Stack, Global Data:
3720---------------------------
3721
3722The implementation of U-Boot is complicated by the fact that U-Boot
3723starts running out of ROM (flash memory), usually without access to
3724system RAM (because the memory controller is not initialized yet).
3725This means that we don't have writable Data or BSS segments, and BSS
3726is not initialized as zero. To be able to get a C environment working
3727at all, we have to allocate at least a minimal stack. Implementation
3728options for this are defined and restricted by the CPU used: Some CPU
3729models provide on-chip memory (like the IMMR area on MPC8xx and
3730MPC826x processors), on others (parts of) the data cache can be
3731locked as (mis-) used as memory, etc.
3732
3733	Chris Hallinan posted a good summary of these issues to the
3734	u-boot-users mailing list:
3735
3736	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3737	From: "Chris Hallinan" <clh@net1plus.com>
3738	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3739	...
3740
3741	Correct me if I'm wrong, folks, but the way I understand it
3742	is this: Using DCACHE as initial RAM for Stack, etc, does not
3743	require any physical RAM backing up the cache. The cleverness
3744	is that the cache is being used as a temporary supply of
3745	necessary storage before the SDRAM controller is setup. It's
3746	beyond the scope of this list to explain the details, but you
3747	can see how this works by studying the cache architecture and
3748	operation in the architecture and processor-specific manuals.
3749
3750	OCM is On Chip Memory, which I believe the 405GP has 4K. It
3751	is another option for the system designer to use as an
3752	initial stack/RAM area prior to SDRAM being available. Either
3753	option should work for you. Using CS 4 should be fine if your
3754	board designers haven't used it for something that would
3755	cause you grief during the initial boot! It is frequently not
3756	used.
3757
3758	CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3759	with your processor/board/system design. The default value
3760	you will find in any recent u-boot distribution in
3761	walnut.h should work for you. I'd set it to a value larger
3762	than your SDRAM module. If you have a 64MB SDRAM module, set
3763	it above 400_0000. Just make sure your board has no resources
3764	that are supposed to respond to that address! That code in
3765	start.S has been around a while and should work as is when
3766	you get the config right.
3767
3768	-Chris Hallinan
3769	DS4.COM, Inc.
3770
3771It is essential to remember this, since it has some impact on the C
3772code for the initialization procedures:
3773
3774* Initialized global data (data segment) is read-only. Do not attempt
3775  to write it.
3776
3777* Do not use any uninitialized global data (or implicitely initialized
3778  as zero data - BSS segment) at all - this is undefined, initiali-
3779  zation is performed later (when relocating to RAM).
3780
3781* Stack space is very limited. Avoid big data buffers or things like
3782  that.
3783
3784Having only the stack as writable memory limits means we cannot use
3785normal global data to share information beween the code. But it
3786turned out that the implementation of U-Boot can be greatly
3787simplified by making a global data structure (gd_t) available to all
3788functions. We could pass a pointer to this data as argument to _all_
3789functions, but this would bloat the code. Instead we use a feature of
3790the GCC compiler (Global Register Variables) to share the data: we
3791place a pointer (gd) to the global data into a register which we
3792reserve for this purpose.
3793
3794When choosing a register for such a purpose we are restricted by the
3795relevant  (E)ABI  specifications for the current architecture, and by
3796GCC's implementation.
3797
3798For PowerPC, the following registers have specific use:
3799	R1:	stack pointer
3800	R2:	reserved for system use
3801	R3-R4:	parameter passing and return values
3802	R5-R10: parameter passing
3803	R13:	small data area pointer
3804	R30:	GOT pointer
3805	R31:	frame pointer
3806
3807	(U-Boot also uses R14 as internal GOT pointer.)
3808
3809    ==> U-Boot will use R2 to hold a pointer to the global data
3810
3811    Note: on PPC, we could use a static initializer (since the
3812    address of the global data structure is known at compile time),
3813    but it turned out that reserving a register results in somewhat
3814    smaller code - although the code savings are not that big (on
3815    average for all boards 752 bytes for the whole U-Boot image,
3816    624 text + 127 data).
3817
3818On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3819	http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3820
3821    ==> U-Boot will use P5 to hold a pointer to the global data
3822
3823On ARM, the following registers are used:
3824
3825	R0:	function argument word/integer result
3826	R1-R3:	function argument word
3827	R9:	GOT pointer
3828	R10:	stack limit (used only if stack checking if enabled)
3829	R11:	argument (frame) pointer
3830	R12:	temporary workspace
3831	R13:	stack pointer
3832	R14:	link register
3833	R15:	program counter
3834
3835    ==> U-Boot will use R8 to hold a pointer to the global data
3836
3837NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3838or current versions of GCC may "optimize" the code too much.
3839
3840Memory Management:
3841------------------
3842
3843U-Boot runs in system state and uses physical addresses, i.e. the
3844MMU is not used either for address mapping nor for memory protection.
3845
3846The available memory is mapped to fixed addresses using the memory
3847controller. In this process, a contiguous block is formed for each
3848memory type (Flash, SDRAM, SRAM), even when it consists of several
3849physical memory banks.
3850
3851U-Boot is installed in the first 128 kB of the first Flash bank (on
3852TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3853booting and sizing and initializing DRAM, the code relocates itself
3854to the upper end of DRAM. Immediately below the U-Boot code some
3855memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3856configuration setting]. Below that, a structure with global Board
3857Info data is placed, followed by the stack (growing downward).
3858
3859Additionally, some exception handler code is copied to the low 8 kB
3860of DRAM (0x00000000 ... 0x00001FFF).
3861
3862So a typical memory configuration with 16 MB of DRAM could look like
3863this:
3864
3865	0x0000 0000	Exception Vector code
3866	      :
3867	0x0000 1FFF
3868	0x0000 2000	Free for Application Use
3869	      :
3870	      :
3871
3872	      :
3873	      :
3874	0x00FB FF20	Monitor Stack (Growing downward)
3875	0x00FB FFAC	Board Info Data and permanent copy of global data
3876	0x00FC 0000	Malloc Arena
3877	      :
3878	0x00FD FFFF
3879	0x00FE 0000	RAM Copy of Monitor Code
3880	...		eventually: LCD or video framebuffer
3881	...		eventually: pRAM (Protected RAM - unchanged by reset)
3882	0x00FF FFFF	[End of RAM]
3883
3884
3885System Initialization:
3886----------------------
3887
3888In the reset configuration, U-Boot starts at the reset entry point
3889(on most PowerPC systems at address 0x00000100). Because of the reset
3890configuration for CS0# this is a mirror of the onboard Flash memory.
3891To be able to re-map memory U-Boot then jumps to its link address.
3892To be able to implement the initialization code in C, a (small!)
3893initial stack is set up in the internal Dual Ported RAM (in case CPUs
3894which provide such a feature like MPC8xx or MPC8260), or in a locked
3895part of the data cache. After that, U-Boot initializes the CPU core,
3896the caches and the SIU.
3897
3898Next, all (potentially) available memory banks are mapped using a
3899preliminary mapping. For example, we put them on 512 MB boundaries
3900(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3901on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3902programmed for SDRAM access. Using the temporary configuration, a
3903simple memory test is run that determines the size of the SDRAM
3904banks.
3905
3906When there is more than one SDRAM bank, and the banks are of
3907different size, the largest is mapped first. For equal size, the first
3908bank (CS2#) is mapped first. The first mapping is always for address
39090x00000000, with any additional banks following immediately to create
3910contiguous memory starting from 0.
3911
3912Then, the monitor installs itself at the upper end of the SDRAM area
3913and allocates memory for use by malloc() and for the global Board
3914Info data; also, the exception vector code is copied to the low RAM
3915pages, and the final stack is set up.
3916
3917Only after this relocation will you have a "normal" C environment;
3918until that you are restricted in several ways, mostly because you are
3919running from ROM, and because the code will have to be relocated to a
3920new address in RAM.
3921
3922
3923U-Boot Porting Guide:
3924----------------------
3925
3926[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3927list, October 2002]
3928
3929
3930int main (int argc, char *argv[])
3931{
3932	sighandler_t no_more_time;
3933
3934	signal (SIGALRM, no_more_time);
3935	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3936
3937	if (available_money > available_manpower) {
3938		pay consultant to port U-Boot;
3939		return 0;
3940	}
3941
3942	Download latest U-Boot source;
3943
3944	Subscribe to u-boot-users mailing list;
3945
3946	if (clueless) {
3947		email ("Hi, I am new to U-Boot, how do I get started?");
3948	}
3949
3950	while (learning) {
3951		Read the README file in the top level directory;
3952		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3953		Read the source, Luke;
3954	}
3955
3956	if (available_money > toLocalCurrency ($2500)) {
3957		Buy a BDI2000;
3958	} else {
3959		Add a lot of aggravation and time;
3960	}
3961
3962	Create your own board support subdirectory;
3963
3964	Create your own board config file;
3965
3966	while (!running) {
3967		do {
3968			Add / modify source code;
3969		} until (compiles);
3970		Debug;
3971		if (clueless)
3972			email ("Hi, I am having problems...");
3973	}
3974	Send patch file to Wolfgang;
3975
3976	return 0;
3977}
3978
3979void no_more_time (int sig)
3980{
3981      hire_a_guru();
3982}
3983
3984
3985Coding Standards:
3986-----------------
3987
3988All contributions to U-Boot should conform to the Linux kernel
3989coding style; see the file "Documentation/CodingStyle" and the script
3990"scripts/Lindent" in your Linux kernel source directory.  In sources
3991originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3992spaces before parameters to function calls) is actually used.
3993
3994Source files originating from a different project (for example the
3995MTD subsystem) are generally exempt from these guidelines and are not
3996reformated to ease subsequent migration to newer versions of those
3997sources.
3998
3999Please note that U-Boot is implemented in C (and to some small parts in
4000Assembler); no C++ is used, so please do not use C++ style comments (//)
4001in your code.
4002
4003Please also stick to the following formatting rules:
4004- remove any trailing white space
4005- use TAB characters for indentation, not spaces
4006- make sure NOT to use DOS '\r\n' line feeds
4007- do not add more than 2 empty lines to source files
4008- do not add trailing empty lines to source files
4009
4010Submissions which do not conform to the standards may be returned
4011with a request to reformat the changes.
4012
4013
4014Submitting Patches:
4015-------------------
4016
4017Since the number of patches for U-Boot is growing, we need to
4018establish some rules. Submissions which do not conform to these rules
4019may be rejected, even when they contain important and valuable stuff.
4020
4021Patches shall be sent to the u-boot-users mailing list.
4022
4023Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4024
4025When you send a patch, please include the following information with
4026it:
4027
4028* For bug fixes: a description of the bug and how your patch fixes
4029  this bug. Please try to include a way of demonstrating that the
4030  patch actually fixes something.
4031
4032* For new features: a description of the feature and your
4033  implementation.
4034
4035* A CHANGELOG entry as plaintext (separate from the patch)
4036
4037* For major contributions, your entry to the CREDITS file
4038
4039* When you add support for a new board, don't forget to add this
4040  board to the MAKEALL script, too.
4041
4042* If your patch adds new configuration options, don't forget to
4043  document these in the README file.
4044
4045* The patch itself. If you are using git (which is *strongly*
4046  recommended) you can easily generate the patch using the
4047  "git-format-patch". If you then use "git-send-email" to send it to
4048  the U-Boot mailing list, you will avoid most of the common problems
4049  with some other mail clients.
4050
4051  If you cannot use git, use "diff -purN OLD NEW". If your version of
4052  diff does not support these options, then get the latest version of
4053  GNU diff.
4054
4055  The current directory when running this command shall be the parent
4056  directory of the U-Boot source tree (i. e. please make sure that
4057  your patch includes sufficient directory information for the
4058  affected files).
4059
4060  We prefer patches as plain text. MIME attachments are discouraged,
4061  and compressed attachments must not be used.
4062
4063* If one logical set of modifications affects or creates several
4064  files, all these changes shall be submitted in a SINGLE patch file.
4065
4066* Changesets that contain different, unrelated modifications shall be
4067  submitted as SEPARATE patches, one patch per changeset.
4068
4069
4070Notes:
4071
4072* Before sending the patch, run the MAKEALL script on your patched
4073  source tree and make sure that no errors or warnings are reported
4074  for any of the boards.
4075
4076* Keep your modifications to the necessary minimum: A patch
4077  containing several unrelated changes or arbitrary reformats will be
4078  returned with a request to re-formatting / split it.
4079
4080* If you modify existing code, make sure that your new code does not
4081  add to the memory footprint of the code ;-) Small is beautiful!
4082  When adding new features, these should compile conditionally only
4083  (using #ifdef), and the resulting code with the new feature
4084  disabled must not need more memory than the old code without your
4085  modification.
4086
4087* Remember that there is a size limit of 40 kB per message on the
4088  u-boot-users mailing list. Bigger patches will be moderated. If
4089  they are reasonable and not bigger than 100 kB, they will be
4090  acknowledged. Even bigger patches should be avoided.
4091