xref: /rk3399_rockchip-uboot/README (revision aaf224ab4ec400abefa17982cbd2ae995adc9978)
1#
2# (C) Copyright 2000 - 2004
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 and ARM processors, which can be
29installed in a boot ROM and used to initialize and test the hardware
30or to download and run application code.
31
32The development of U-Boot is closely related to Linux: some parts of
33the source code originate in the Linux source tree, we have some
34header files in common, and special provision has been made to
35support booting of Linux images.
36
37Some attention has been paid to make this software easily
38configurable and extendable. For instance, all monitor commands are
39implemented with the same call interface, so that it's very easy to
40add new commands. Also, instead of permanently adding rarely used
41code (for instance hardware test utilities) to the monitor, you can
42load and run it dynamically.
43
44
45Status:
46=======
47
48In general, all boards for which a configuration option exists in the
49Makefile have been tested to some extent and can be considered
50"working". In fact, many of them are used in production systems.
51
52In case of problems see the CHANGELOG and CREDITS files to find out
53who contributed the specific port.
54
55
56Where to get help:
57==================
58
59In case you have questions about, problems with or contributions for
60U-Boot you should send a message to the U-Boot mailing list at
61<u-boot-users@lists.sourceforge.net>. There is also an archive of
62previous traffic on the mailing list - please search the archive
63before asking FAQ's. Please see
64http://lists.sourceforge.net/lists/listinfo/u-boot-users/
65
66
67Where we come from:
68===================
69
70- start from 8xxrom sources
71- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
72- clean up code
73- make it easier to add custom boards
74- make it possible to add other [PowerPC] CPUs
75- extend functions, especially:
76  * Provide extended interface to Linux boot loader
77  * S-Record download
78  * network boot
79  * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80- create ARMBoot project (http://sourceforge.net/projects/armboot)
81- add other CPU families (starting with ARM)
82- create U-Boot project (http://sourceforge.net/projects/u-boot)
83
84
85Names and Spelling:
86===================
87
88The "official" name of this project is "Das U-Boot". The spelling
89"U-Boot" shall be used in all written text (documentation, comments
90in source files etc.). Example:
91
92	This is the README file for the U-Boot project.
93
94File names etc. shall be based on the string "u-boot". Examples:
95
96	include/asm-ppc/u-boot.h
97
98	#include <asm/u-boot.h>
99
100Variable names, preprocessor constants etc. shall be either based on
101the string "u_boot" or on "U_BOOT". Example:
102
103	U_BOOT_VERSION		u_boot_logo
104	IH_OS_U_BOOT		u_boot_hush_start
105
106
107Versioning:
108===========
109
110U-Boot uses a 3 level version number containing a version, a
111sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112sub-version "34", and patchlevel "4".
113
114The patchlevel is used to indicate certain stages of development
115between released versions, i. e. officially released versions of
116U-Boot will always have a patchlevel of "0".
117
118
119Directory Hierarchy:
120====================
121
122- board		Board dependent files
123- common	Misc architecture independent functions
124- cpu		CPU specific files
125  - 74xx_7xx	Files specific to Motorola MPC74xx and 7xx CPUs
126  - arm720t	Files specific to ARM 720 CPUs
127  - arm920t	Files specific to ARM 920 CPUs
128  - arm925t	Files specific to ARM 925 CPUs
129  - arm926ejs	Files specific to ARM 926 CPUs
130  - at91rm9200	Files specific to Atmel AT91RM9200 CPUs
131  - i386	Files specific to i386 CPUs
132  - ixp		Files specific to Intel XScale IXP CPUs
133  - mcf52x2	Files specific to Motorola ColdFire MCF52x2 CPUs
134  - mips	Files specific to MIPS CPUs
135  - mpc5xx	Files specific to Motorola MPC5xx  CPUs
136  - mpc5xxx	Files specific to Motorola MPC5xxx CPUs
137  - mpc8xx	Files specific to Motorola MPC8xx  CPUs
138  - mpc824x	Files specific to Motorola MPC824x CPUs
139  - mpc8260	Files specific to Motorola MPC8260 CPUs
140  - mpc85xx	Files specific to Motorola MPC85xx CPUs
141  - nios	Files specific to Altera NIOS CPUs
142  - ppc4xx	Files specific to IBM PowerPC 4xx CPUs
143  - pxa		Files specific to Intel XScale PXA CPUs
144  - s3c44b0	Files specific to Samsung S3C44B0 CPUs
145  - sa1100	Files specific to Intel StrongARM SA1100 CPUs
146- disk		Code for disk drive partition handling
147- doc		Documentation (don't expect too much)
148- drivers	Commonly used device drivers
149- dtt		Digital Thermometer and Thermostat drivers
150- examples	Example code for standalone applications, etc.
151- include	Header Files
152- lib_arm	Files generic to ARM	 architecture
153- lib_generic	Files generic to all	 architectures
154- lib_i386	Files generic to i386	 architecture
155- lib_m68k	Files generic to m68k	 architecture
156- lib_mips	Files generic to MIPS	 architecture
157- lib_nios	Files generic to NIOS	 architecture
158- lib_ppc	Files generic to PowerPC architecture
159- net		Networking code
160- post		Power On Self Test
161- rtc		Real Time Clock drivers
162- tools		Tools to build S-Record or U-Boot images, etc.
163
164Software Configuration:
165=======================
166
167Configuration is usually done using C preprocessor defines; the
168rationale behind that is to avoid dead code whenever possible.
169
170There are two classes of configuration variables:
171
172* Configuration _OPTIONS_:
173  These are selectable by the user and have names beginning with
174  "CONFIG_".
175
176* Configuration _SETTINGS_:
177  These depend on the hardware etc. and should not be meddled with if
178  you don't know what you're doing; they have names beginning with
179  "CFG_".
180
181Later we will add a configuration tool - probably similar to or even
182identical to what's used for the Linux kernel. Right now, we have to
183do the configuration by hand, which means creating some symbolic
184links and editing some configuration files. We use the TQM8xxL boards
185as an example here.
186
187
188Selection of Processor Architecture and Board Type:
189---------------------------------------------------
190
191For all supported boards there are ready-to-use default
192configurations available; just type "make <board_name>_config".
193
194Example: For a TQM823L module type:
195
196	cd u-boot
197	make TQM823L_config
198
199For the Cogent platform, you need to specify the cpu type as well;
200e.g. "make cogent_mpc8xx_config". And also configure the cogent
201directory according to the instructions in cogent/README.
202
203
204Configuration Options:
205----------------------
206
207Configuration depends on the combination of board and CPU type; all
208such information is kept in a configuration file
209"include/configs/<board_name>.h".
210
211Example: For a TQM823L module, all configuration settings are in
212"include/configs/TQM823L.h".
213
214
215Many of the options are named exactly as the corresponding Linux
216kernel configuration options. The intention is to make it easier to
217build a config tool - later.
218
219
220The following options need to be configured:
221
222- CPU Type:	Define exactly one of
223
224		PowerPC based CPUs:
225		-------------------
226		CONFIG_MPC823,	CONFIG_MPC850,	CONFIG_MPC855,	CONFIG_MPC860
227	or	CONFIG_MPC5xx
228	or	CONFIG_MPC824X, CONFIG_MPC8260
229	or	CONFIG_MPC85xx
230	or	CONFIG_IOP480
231	or	CONFIG_405GP
232	or	CONFIG_405EP
233	or	CONFIG_440
234	or	CONFIG_MPC74xx
235	or	CONFIG_750FX
236
237		ARM based CPUs:
238		---------------
239		CONFIG_SA1110
240		CONFIG_ARM7
241		CONFIG_PXA250
242
243
244- Board Type:	Define exactly one of
245
246		PowerPC based boards:
247		---------------------
248
249		CONFIG_ADCIOP,	   CONFIG_ICU862      CONFIG_RPXsuper,
250		CONFIG_ADS860,	   CONFIG_IP860,      CONFIG_SM850,
251		CONFIG_AMX860,	   CONFIG_IPHASE4539, CONFIG_SPD823TS,
252		CONFIG_AR405,	   CONFIG_IVML24,     CONFIG_SXNI855T,
253		CONFIG_BAB7xx,	   CONFIG_IVML24_128, CONFIG_Sandpoint8240,
254		CONFIG_CANBT,	   CONFIG_IVML24_256, CONFIG_Sandpoint8245,
255		CONFIG_CCM,	   CONFIG_IVMS8,      CONFIG_TQM823L,
256		CONFIG_CPCI405,	   CONFIG_IVMS8_128,  CONFIG_TQM850L,
257		CONFIG_CPCI4052,   CONFIG_IVMS8_256,  CONFIG_TQM855L,
258		CONFIG_CPCIISER4,  CONFIG_LANTEC,     CONFIG_TQM860L,
259		CONFIG_CPU86,	   CONFIG_MBX,	      CONFIG_TQM8260,
260		CONFIG_CRAYL1,	   CONFIG_MBX860T,    CONFIG_TTTech,
261		CONFIG_CU824,	   CONFIG_MHPC,	      CONFIG_UTX8245,
262		CONFIG_DASA_SIM,   CONFIG_MIP405,     CONFIG_W7OLMC,
263		CONFIG_DU405,	   CONFIG_MOUSSE,     CONFIG_W7OLMG,
264		CONFIG_ELPPC,	   CONFIG_MPC8260ADS, CONFIG_WALNUT405,
265		CONFIG_ERIC,	   CONFIG_MUSENKI,    CONFIG_ZUMA,
266		CONFIG_ESTEEM192E, CONFIG_MVS1,	      CONFIG_c2mon,
267		CONFIG_ETX094,	   CONFIG_NX823,      CONFIG_cogent_mpc8260,
268		CONFIG_EVB64260,   CONFIG_OCRTC,      CONFIG_cogent_mpc8xx,
269		CONFIG_FADS823,	   CONFIG_ORSG,	      CONFIG_ep8260,
270		CONFIG_FADS850SAR, CONFIG_OXC,	      CONFIG_gw8260,
271		CONFIG_FADS860T,   CONFIG_PCI405,     CONFIG_hermes,
272		CONFIG_FLAGADM,	   CONFIG_PCIPPC2,    CONFIG_hymod,
273		CONFIG_FPS850L,	   CONFIG_PCIPPC6,    CONFIG_lwmon,
274		CONFIG_GEN860T,	   CONFIG_PIP405,     CONFIG_pcu_e,
275		CONFIG_GENIETV,	   CONFIG_PM826,      CONFIG_ppmc8260,
276		CONFIG_GTH,	   CONFIG_RPXClassic, CONFIG_rsdproto,
277		CONFIG_IAD210,	   CONFIG_RPXlite,    CONFIG_sbc8260,
278		CONFIG_EBONY,	   CONFIG_sacsng,     CONFIG_FPS860L,
279		CONFIG_V37,	   CONFIG_ELPT860,    CONFIG_CMI,
280		CONFIG_NETVIA,	   CONFIG_RBC823,     CONFIG_ZPC1900,
281		CONFIG_MPC8540ADS, CONFIG_MPC8560ADS, CONFIG_QS850,
282		CONFIG_QS823,	   CONFIG_QS860T,     CONFIG_DB64360,
283		CONFIG_DB64460,	   CONFIG_DUET_ADS
284
285		ARM based boards:
286		-----------------
287
288		CONFIG_HHP_CRADLE,  CONFIG_DNP1110,	CONFIG_EP7312,
289		CONFIG_IMPA7,	    CONFIG_LART,	CONFIG_LUBBOCK,
290		CONFIG_INNOVATOROMAP1510,      CONFIG_INNOVATOROMAP1610,
291		CONFIG_H2_OMAP1610, CONFIG_SHANNON,	CONFIG_SMDK2400,
292		CONFIG_SMDK2410,    CONFIG_TRAB,	CONFIG_VCMA9,
293		CONFIG_AT91RM9200DK
294
295
296- CPU Module Type: (if CONFIG_COGENT is defined)
297		Define exactly one of
298		CONFIG_CMA286_60_OLD
299--- FIXME --- not tested yet:
300		CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
301		CONFIG_CMA287_23, CONFIG_CMA287_50
302
303- Motherboard Type: (if CONFIG_COGENT is defined)
304		Define exactly one of
305		CONFIG_CMA101, CONFIG_CMA102
306
307- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
308		Define one or more of
309		CONFIG_CMA302
310
311- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
312		Define one or more of
313		CONFIG_LCD_HEARTBEAT	- update a character position on
314					  the lcd display every second with
315					  a "rotator" |\-/|\-/
316
317- Board flavour: (if CONFIG_MPC8260ADS is defined)
318		CONFIG_ADSTYPE
319		Possible values are:
320			CFG_8260ADS	- original MPC8260ADS
321			CFG_8266ADS	- MPC8266ADS
322			CFG_PQ2FADS	- PQ2FADS-ZU or PQ2FADS-VR
323
324
325- MPC824X Family Member (if CONFIG_MPC824X is defined)
326		Define exactly one of
327		CONFIG_MPC8240, CONFIG_MPC8245
328
329- 8xx CPU Options: (if using an MPC8xx cpu)
330		Define one or more of
331		CONFIG_8xx_GCLK_FREQ	- if get_gclk_freq() cannot work
332					  e.g. if there is no 32KHz
333					  reference PIT/RTC clock
334
335- 859/866 CPU options: (if using a MPC859 or MPC866 CPU):
336		CFG_866_OSCCLK
337		CFG_866_CPUCLK_MIN
338		CFG_866_CPUCLK_MAX
339		CFG_866_CPUCLK_DEFAULT
340			See doc/README.MPC866
341
342		CFG_MEASURE_CPUCLK
343
344		Define this to measure the actual CPU clock instead
345		of relying on the correctness of the configured
346		values. Mostly useful for board bringup to make sure
347		the PLL is locked at the intended frequency. Note
348		that this requires a (stable) reference clock (32 kHz
349		RTC clock),
350
351- Linux Kernel Interface:
352		CONFIG_CLOCKS_IN_MHZ
353
354		U-Boot stores all clock information in Hz
355		internally. For binary compatibility with older Linux
356		kernels (which expect the clocks passed in the
357		bd_info data to be in MHz) the environment variable
358		"clocks_in_mhz" can be defined so that U-Boot
359		converts clock data to MHZ before passing it to the
360		Linux kernel.
361		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
362		"clocks_in_mhz=1" is  automatically  included  in  the
363		default environment.
364
365		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]
366
367		When transfering memsize parameter to linux, some versions
368		expect it to be in bytes, others in MB.
369		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
370
371- Console Interface:
372		Depending on board, define exactly one serial port
373		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
374		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
375		console by defining CONFIG_8xx_CONS_NONE
376
377		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
378		port routines must be defined elsewhere
379		(i.e. serial_init(), serial_getc(), ...)
380
381		CONFIG_CFB_CONSOLE
382		Enables console device for a color framebuffer. Needs following
383		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
384			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
385						(default big endian)
386			VIDEO_HW_RECTFILL	graphic chip supports
387						rectangle fill
388						(cf. smiLynxEM)
389			VIDEO_HW_BITBLT		graphic chip supports
390						bit-blit (cf. smiLynxEM)
391			VIDEO_VISIBLE_COLS	visible pixel columns
392						(cols=pitch)
393			VIDEO_VISIBLE_ROWS	visible pixel rows
394			VIDEO_PIXEL_SIZE	bytes per pixel
395			VIDEO_DATA_FORMAT	graphic data format
396						(0-5, cf. cfb_console.c)
397			VIDEO_FB_ADRS		framebuffer address
398			VIDEO_KBD_INIT_FCT	keyboard int fct
399						(i.e. i8042_kbd_init())
400			VIDEO_TSTC_FCT		test char fct
401						(i.e. i8042_tstc)
402			VIDEO_GETC_FCT		get char fct
403						(i.e. i8042_getc)
404			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
405						(requires blink timer
406						cf. i8042.c)
407			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
408			CONFIG_CONSOLE_TIME	display time/date info in
409						upper right corner
410						(requires CFG_CMD_DATE)
411			CONFIG_VIDEO_LOGO	display Linux logo in
412						upper left corner
413			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
414						linux_logo.h for logo.
415						Requires CONFIG_VIDEO_LOGO
416			CONFIG_CONSOLE_EXTRA_INFO
417						addional board info beside
418						the logo
419
420		When CONFIG_CFB_CONSOLE is defined, video console is
421		default i/o. Serial console can be forced with
422		environment 'console=serial'.
423
424		When CONFIG_SILENT_CONSOLE is defined, all console
425		messages (by U-Boot and Linux!) can be silenced with
426		the "silent" environment variable. See
427		doc/README.silent for more information.
428
429- Console Baudrate:
430		CONFIG_BAUDRATE - in bps
431		Select one of the baudrates listed in
432		CFG_BAUDRATE_TABLE, see below.
433		CFG_BRGCLK_PRESCALE, baudrate prescale
434
435- Interrupt driven serial port input:
436		CONFIG_SERIAL_SOFTWARE_FIFO
437
438		PPC405GP only.
439		Use an interrupt handler for receiving data on the
440		serial port. It also enables using hardware handshake
441		(RTS/CTS) and UART's built-in FIFO. Set the number of
442		bytes the interrupt driven input buffer should have.
443
444		Set to 0 to disable this feature (this is the default).
445		This will also disable hardware handshake.
446
447- Console UART Number:
448		CONFIG_UART1_CONSOLE
449
450		IBM PPC4xx only.
451		If defined internal UART1 (and not UART0) is used
452		as default U-Boot console.
453
454- Boot Delay:	CONFIG_BOOTDELAY - in seconds
455		Delay before automatically booting the default image;
456		set to -1 to disable autoboot.
457
458		See doc/README.autoboot for these options that
459		work with CONFIG_BOOTDELAY. None are required.
460		CONFIG_BOOT_RETRY_TIME
461		CONFIG_BOOT_RETRY_MIN
462		CONFIG_AUTOBOOT_KEYED
463		CONFIG_AUTOBOOT_PROMPT
464		CONFIG_AUTOBOOT_DELAY_STR
465		CONFIG_AUTOBOOT_STOP_STR
466		CONFIG_AUTOBOOT_DELAY_STR2
467		CONFIG_AUTOBOOT_STOP_STR2
468		CONFIG_ZERO_BOOTDELAY_CHECK
469		CONFIG_RESET_TO_RETRY
470
471- Autoboot Command:
472		CONFIG_BOOTCOMMAND
473		Only needed when CONFIG_BOOTDELAY is enabled;
474		define a command string that is automatically executed
475		when no character is read on the console interface
476		within "Boot Delay" after reset.
477
478		CONFIG_BOOTARGS
479		This can be used to pass arguments to the bootm
480		command. The value of CONFIG_BOOTARGS goes into the
481		environment value "bootargs".
482
483		CONFIG_RAMBOOT and CONFIG_NFSBOOT
484		The value of these goes into the environment as
485		"ramboot" and "nfsboot" respectively, and can be used
486		as a convenience, when switching between booting from
487		ram and nfs.
488
489- Pre-Boot Commands:
490		CONFIG_PREBOOT
491
492		When this option is #defined, the existence of the
493		environment variable "preboot" will be checked
494		immediately before starting the CONFIG_BOOTDELAY
495		countdown and/or running the auto-boot command resp.
496		entering interactive mode.
497
498		This feature is especially useful when "preboot" is
499		automatically generated or modified. For an example
500		see the LWMON board specific code: here "preboot" is
501		modified when the user holds down a certain
502		combination of keys on the (special) keyboard when
503		booting the systems
504
505- Serial Download Echo Mode:
506		CONFIG_LOADS_ECHO
507		If defined to 1, all characters received during a
508		serial download (using the "loads" command) are
509		echoed back. This might be needed by some terminal
510		emulations (like "cu"), but may as well just take
511		time on others. This setting #define's the initial
512		value of the "loads_echo" environment variable.
513
514- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
515		CONFIG_KGDB_BAUDRATE
516		Select one of the baudrates listed in
517		CFG_BAUDRATE_TABLE, see below.
518
519- Monitor Functions:
520		CONFIG_COMMANDS
521		Most monitor functions can be selected (or
522		de-selected) by adjusting the definition of
523		CONFIG_COMMANDS; to select individual functions,
524		#define CONFIG_COMMANDS by "OR"ing any of the
525		following values:
526
527		#define enables commands:
528		-------------------------
529		CFG_CMD_ASKENV	* ask for env variable
530		CFG_CMD_AUTOSCRIPT Autoscript Support
531		CFG_CMD_BDI	  bdinfo
532		CFG_CMD_BEDBUG	  Include BedBug Debugger
533		CFG_CMD_BMP	* BMP support
534		CFG_CMD_BOOTD	  bootd
535		CFG_CMD_CACHE	  icache, dcache
536		CFG_CMD_CONSOLE	  coninfo
537		CFG_CMD_DATE	* support for RTC, date/time...
538		CFG_CMD_DHCP	  DHCP support
539		CFG_CMD_DIAG	* Diagnostics
540		CFG_CMD_DOC	* Disk-On-Chip Support
541		CFG_CMD_DTT	  Digital Therm and Thermostat
542		CFG_CMD_ECHO	* echo arguments
543		CFG_CMD_EEPROM	* EEPROM read/write support
544		CFG_CMD_ELF	  bootelf, bootvx
545		CFG_CMD_ENV	  saveenv
546		CFG_CMD_FDC	* Floppy Disk Support
547		CFG_CMD_FAT	  FAT partition support
548		CFG_CMD_FDOS	* Dos diskette Support
549		CFG_CMD_FLASH	  flinfo, erase, protect
550		CFG_CMD_FPGA	  FPGA device initialization support
551		CFG_CMD_HWFLOW	* RTS/CTS hw flow control
552		CFG_CMD_I2C	* I2C serial bus support
553		CFG_CMD_IDE	* IDE harddisk support
554		CFG_CMD_IMI	  iminfo
555		CFG_CMD_IMLS	  List all found images
556		CFG_CMD_IMMAP	* IMMR dump support
557		CFG_CMD_IRQ	* irqinfo
558		CFG_CMD_ITEST	* Integer/string test of 2 values
559		CFG_CMD_JFFS2	* JFFS2 Support
560		CFG_CMD_KGDB	* kgdb
561		CFG_CMD_LOADB	  loadb
562		CFG_CMD_LOADS	  loads
563		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
564				  loop, mtest
565		CFG_CMD_MISC	  Misc functions like sleep etc
566		CFG_CMD_MMC	  MMC memory mapped support
567		CFG_CMD_MII	  MII utility commands
568		CFG_CMD_NAND	* NAND support
569		CFG_CMD_NET	  bootp, tftpboot, rarpboot
570		CFG_CMD_PCI	* pciinfo
571		CFG_CMD_PCMCIA	* PCMCIA support
572		CFG_CMD_PING	* send ICMP ECHO_REQUEST to network host
573		CFG_CMD_PORTIO	* Port I/O
574		CFG_CMD_REGINFO * Register dump
575		CFG_CMD_RUN	  run command in env variable
576		CFG_CMD_SAVES	  save S record dump
577		CFG_CMD_SCSI	* SCSI Support
578		CFG_CMD_SDRAM	* print SDRAM configuration information
579		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
580		CFG_CMD_SPI	* SPI serial bus support
581		CFG_CMD_USB	* USB support
582		CFG_CMD_VFD	* VFD support (TRAB)
583		CFG_CMD_BSP	* Board SPecific functions
584		-----------------------------------------------
585		CFG_CMD_ALL	all
586
587		CFG_CMD_DFL	Default configuration; at the moment
588				this is includes all commands, except
589				the ones marked with "*" in the list
590				above.
591
592		If you don't define CONFIG_COMMANDS it defaults to
593		CFG_CMD_DFL in include/cmd_confdefs.h. A board can
594		override the default settings in the respective
595		include file.
596
597		EXAMPLE: If you want all functions except of network
598		support you can write:
599
600		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
601
602
603	Note:	Don't enable the "icache" and "dcache" commands
604		(configuration option CFG_CMD_CACHE) unless you know
605		what you (and your U-Boot users) are doing. Data
606		cache cannot be enabled on systems like the 8xx or
607		8260 (where accesses to the IMMR region must be
608		uncached), and it cannot be disabled on all other
609		systems where we (mis-) use the data cache to hold an
610		initial stack and some data.
611
612
613		XXX - this list needs to get updated!
614
615- Watchdog:
616		CONFIG_WATCHDOG
617		If this variable is defined, it enables watchdog
618		support. There must be support in the platform specific
619		code for a watchdog. For the 8xx and 8260 CPUs, the
620		SIU Watchdog feature is enabled in the SYPCR
621		register.
622
623- U-Boot Version:
624		CONFIG_VERSION_VARIABLE
625		If this variable is defined, an environment variable
626		named "ver" is created by U-Boot showing the U-Boot
627		version as printed by the "version" command.
628		This variable is readonly.
629
630- Real-Time Clock:
631
632		When CFG_CMD_DATE is selected, the type of the RTC
633		has to be selected, too. Define exactly one of the
634		following options:
635
636		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
637		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
638		CONFIG_RTC_MC146818	- use MC146818 RTC
639		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
640		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
641		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
642		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
643
644		Note that if the RTC uses I2C, then the I2C interface
645		must also be configured. See I2C Support, below.
646
647- Timestamp Support:
648
649		When CONFIG_TIMESTAMP is selected, the timestamp
650		(date and time) of an image is printed by image
651		commands like bootm or iminfo. This option is
652		automatically enabled when you select CFG_CMD_DATE .
653
654- Partition Support:
655		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
656		and/or CONFIG_ISO_PARTITION
657
658		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
659		CFG_CMD_SCSI) you must configure support for at least
660		one partition type as well.
661
662- IDE Reset method:
663		CONFIG_IDE_RESET_ROUTINE - this is defined in several
664		board configurations files but used nowhere!
665
666		CONFIG_IDE_RESET - is this is defined, IDE Reset will
667		be performed by calling the function
668			ide_set_reset(int reset)
669		which has to be defined in a board specific file
670
671- ATAPI Support:
672		CONFIG_ATAPI
673
674		Set this to enable ATAPI support.
675
676- LBA48 Support
677		CONFIG_LBA48
678
679		Set this to enable support for disks larger than 137GB
680		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
681		Whithout these , LBA48 support uses 32bit variables and will 'only'
682		support disks up to 2.1TB.
683
684		CFG_64BIT_LBA:
685			When enabled, makes the IDE subsystem use 64bit sector addresses.
686			Default is 32bit.
687
688- SCSI Support:
689		At the moment only there is only support for the
690		SYM53C8XX SCSI controller; define
691		CONFIG_SCSI_SYM53C8XX to enable it.
692
693		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
694		CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
695		CFG_SCSI_MAX_LUN] can be adjusted to define the
696		maximum numbers of LUNs, SCSI ID's and target
697		devices.
698		CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
699
700- NETWORK Support (PCI):
701		CONFIG_E1000
702		Support for Intel 8254x gigabit chips.
703
704		CONFIG_EEPRO100
705		Support for Intel 82557/82559/82559ER chips.
706		Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
707		write routine for first time initialisation.
708
709		CONFIG_TULIP
710		Support for Digital 2114x chips.
711		Optional CONFIG_TULIP_SELECT_MEDIA for board specific
712		modem chip initialisation (KS8761/QS6611).
713
714		CONFIG_NATSEMI
715		Support for National dp83815 chips.
716
717		CONFIG_NS8382X
718		Support for National dp8382[01] gigabit chips.
719
720- NETWORK Support (other):
721
722		CONFIG_DRIVER_LAN91C96
723		Support for SMSC's LAN91C96 chips.
724
725			CONFIG_LAN91C96_BASE
726			Define this to hold the physical address
727			of the LAN91C96's I/O space
728
729			CONFIG_LAN91C96_USE_32_BIT
730			Define this to enable 32 bit addressing
731
732- USB Support:
733		At the moment only the UHCI host controller is
734		supported (PIP405, MIP405, MPC5200); define
735		CONFIG_USB_UHCI to enable it.
736		define CONFIG_USB_KEYBOARD to enable the USB Keyboard
737		end define CONFIG_USB_STORAGE to enable the USB
738		storage devices.
739		Note:
740		Supported are USB Keyboards and USB Floppy drives
741		(TEAC FD-05PUB).
742		MPC5200 USB requires additional defines:
743			CONFIG_USB_CLOCK
744				for 528 MHz Clock: 0x0001bbbb
745			CONFIG_USB_CONFIG
746				for differential drivers: 0x00001000
747				for single ended drivers: 0x00005000
748
749
750- MMC Support:
751		The MMC controller on the Intel PXA is supported. To
752		enable this define CONFIG_MMC. The MMC can be
753		accessed from the boot prompt by mapping the device
754		to physical memory similar to flash. Command line is
755		enabled with CFG_CMD_MMC. The MMC driver also works with
756		the FAT fs. This is enabled with CFG_CMD_FAT.
757
758- Keyboard Support:
759		CONFIG_ISA_KEYBOARD
760
761		Define this to enable standard (PC-Style) keyboard
762		support
763
764		CONFIG_I8042_KBD
765		Standard PC keyboard driver with US (is default) and
766		GERMAN key layout (switch via environment 'keymap=de') support.
767		Export function i8042_kbd_init, i8042_tstc and i8042_getc
768		for cfb_console. Supports cursor blinking.
769
770- Video support:
771		CONFIG_VIDEO
772
773		Define this to enable video support (for output to
774		video).
775
776		CONFIG_VIDEO_CT69000
777
778		Enable Chips & Technologies 69000 Video chip
779
780		CONFIG_VIDEO_SMI_LYNXEM
781		Enable Silicon Motion SMI 712/710/810 Video chip
782		Videomode are selected via environment 'videomode' with
783		standard LiLo mode numbers.
784		Following modes are supported  (* is default):
785
786			    800x600  1024x768  1280x1024
787	      256  (8bit)     303*	305	  307
788	    65536 (16bit)     314	317	  31a
789	16,7 Mill (24bit)     315	318	  31b
790		(i.e. setenv videomode 317; saveenv; reset;)
791
792		CONFIG_VIDEO_SED13806
793		Enable Epson SED13806 driver. This driver supports 8bpp
794		and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
795		or CONFIG_VIDEO_SED13806_16BPP
796
797- Keyboard Support:
798		CONFIG_KEYBOARD
799
800		Define this to enable a custom keyboard support.
801		This simply calls drv_keyboard_init() which must be
802		defined in your board-specific files.
803		The only board using this so far is RBC823.
804
805- LCD Support:	CONFIG_LCD
806
807		Define this to enable LCD support (for output to LCD
808		display); also select one of the supported displays
809		by defining one of these:
810
811		CONFIG_NEC_NL6448AC33:
812
813			NEC NL6448AC33-18. Active, color, single scan.
814
815		CONFIG_NEC_NL6448BC20
816
817			NEC NL6448BC20-08. 6.5", 640x480.
818			Active, color, single scan.
819
820		CONFIG_NEC_NL6448BC33_54
821
822			NEC NL6448BC33-54. 10.4", 640x480.
823			Active, color, single scan.
824
825		CONFIG_SHARP_16x9
826
827			Sharp 320x240. Active, color, single scan.
828			It isn't 16x9, and I am not sure what it is.
829
830		CONFIG_SHARP_LQ64D341
831
832			Sharp LQ64D341 display, 640x480.
833			Active, color, single scan.
834
835		CONFIG_HLD1045
836
837			HLD1045 display, 640x480.
838			Active, color, single scan.
839
840		CONFIG_OPTREX_BW
841
842			Optrex	 CBL50840-2 NF-FW 99 22 M5
843			or
844			Hitachi	 LMG6912RPFC-00T
845			or
846			Hitachi	 SP14Q002
847
848			320x240. Black & white.
849
850		Normally display is black on white background; define
851		CFG_WHITE_ON_BLACK to get it inverted.
852
853- Splash Screen Support: CONFIG_SPLASH_SCREEN
854
855		If this option is set, the environment is checked for
856		a variable "splashimage". If found, the usual display
857		of logo, copyright and system information on the LCD
858		is supressed and the BMP image at the address
859		specified in "splashimage" is loaded instead. The
860		console is redirected to the "nulldev", too. This
861		allows for a "silent" boot where a splash screen is
862		loaded very quickly after power-on.
863
864- Compression support:
865		CONFIG_BZIP2
866
867		If this option is set, support for bzip2 compressed
868		images is included. If not, only uncompressed and gzip
869		compressed images are supported.
870
871		NOTE: the bzip2 algorithm requires a lot of RAM, so
872		the malloc area (as defined by CFG_MALLOC_LEN) should
873		be at least 4MB.
874
875- Ethernet address:
876		CONFIG_ETHADDR
877		CONFIG_ETH2ADDR
878		CONFIG_ETH3ADDR
879
880		Define a default value for ethernet address to use
881		for the respective ethernet interface, in case this
882		is not determined automatically.
883
884- IP address:
885		CONFIG_IPADDR
886
887		Define a default value for the IP address to use for
888		the default ethernet interface, in case this is not
889		determined through e.g. bootp.
890
891- Server IP address:
892		CONFIG_SERVERIP
893
894		Defines a default value for theIP address of a TFTP
895		server to contact when using the "tftboot" command.
896
897- BOOTP Recovery Mode:
898		CONFIG_BOOTP_RANDOM_DELAY
899
900		If you have many targets in a network that try to
901		boot using BOOTP, you may want to avoid that all
902		systems send out BOOTP requests at precisely the same
903		moment (which would happen for instance at recovery
904		from a power failure, when all systems will try to
905		boot, thus flooding the BOOTP server. Defining
906		CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
907		inserted before sending out BOOTP requests. The
908		following delays are insterted then:
909
910		1st BOOTP request:	delay 0 ... 1 sec
911		2nd BOOTP request:	delay 0 ... 2 sec
912		3rd BOOTP request:	delay 0 ... 4 sec
913		4th and following
914		BOOTP requests:		delay 0 ... 8 sec
915
916- DHCP Advanced Options:
917		CONFIG_BOOTP_MASK
918
919		You can fine tune the DHCP functionality by adding
920		these flags to the CONFIG_BOOTP_MASK define:
921
922		CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
923		serverip from a DHCP server, it is possible that more
924		than one DNS serverip is offered to the client.
925		If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
926		serverip will be stored in the additional environment
927		variable "dnsip2". The first DNS serverip is always
928		stored in the variable "dnsip", when CONFIG_BOOTP_DNS
929		is added to the CONFIG_BOOTP_MASK.
930
931		CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
932		to do a dynamic update of a DNS server. To do this, they
933		need the hostname of the DHCP requester.
934		If CONFIG_BOOP_SEND_HOSTNAME is added to the
935		CONFIG_BOOTP_MASK, the content of the "hostname"
936		environment variable is passed as option 12 to
937		the DHCP server.
938
939- Status LED:	CONFIG_STATUS_LED
940
941		Several configurations allow to display the current
942		status using a LED. For instance, the LED will blink
943		fast while running U-Boot code, stop blinking as
944		soon as a reply to a BOOTP request was received, and
945		start blinking slow once the Linux kernel is running
946		(supported by a status LED driver in the Linux
947		kernel). Defining CONFIG_STATUS_LED enables this
948		feature in U-Boot.
949
950- CAN Support:	CONFIG_CAN_DRIVER
951
952		Defining CONFIG_CAN_DRIVER enables CAN driver support
953		on those systems that support this (optional)
954		feature, like the TQM8xxL modules.
955
956- I2C Support:	CONFIG_HARD_I2C | CONFIG_SOFT_I2C
957
958		These enable I2C serial bus commands. Defining either of
959		(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
960		include the appropriate I2C driver for the selected cpu.
961
962		This will allow you to use i2c commands at the u-boot
963		command line (as long as you set CFG_CMD_I2C in
964		CONFIG_COMMANDS) and communicate with i2c based realtime
965		clock chips. See common/cmd_i2c.c for a description of the
966		command line interface.
967
968		CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
969
970		CONFIG_SOFT_I2C configures u-boot to use a software (aka
971		bit-banging) driver instead of CPM or similar hardware
972		support for I2C.
973
974		There are several other quantities that must also be
975		defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
976
977		In both cases you will need to define CFG_I2C_SPEED
978		to be the frequency (in Hz) at which you wish your i2c bus
979		to run and CFG_I2C_SLAVE to be the address of this node (ie
980		the cpu's i2c node address).
981
982		Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
983		sets the cpu up as a master node and so its address should
984		therefore be cleared to 0 (See, eg, MPC823e User's Manual
985		p.16-473). So, set CFG_I2C_SLAVE to 0.
986
987		That's all that's required for CONFIG_HARD_I2C.
988
989		If you use the software i2c interface (CONFIG_SOFT_I2C)
990		then the following macros need to be defined (examples are
991		from include/configs/lwmon.h):
992
993		I2C_INIT
994
995		(Optional). Any commands necessary to enable the I2C
996		controller or configure ports.
997
998		eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |=	PB_SCL)
999
1000		I2C_PORT
1001
1002		(Only for MPC8260 CPU). The I/O port to use (the code
1003		assumes both bits are on the same port). Valid values
1004		are 0..3 for ports A..D.
1005
1006		I2C_ACTIVE
1007
1008		The code necessary to make the I2C data line active
1009		(driven).  If the data line is open collector, this
1010		define can be null.
1011
1012		eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |=  PB_SDA)
1013
1014		I2C_TRISTATE
1015
1016		The code necessary to make the I2C data line tri-stated
1017		(inactive).  If the data line is open collector, this
1018		define can be null.
1019
1020		eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1021
1022		I2C_READ
1023
1024		Code that returns TRUE if the I2C data line is high,
1025		FALSE if it is low.
1026
1027		eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1028
1029		I2C_SDA(bit)
1030
1031		If <bit> is TRUE, sets the I2C data line high. If it
1032		is FALSE, it clears it (low).
1033
1034		eg: #define I2C_SDA(bit) \
1035			if(bit) immr->im_cpm.cp_pbdat |=  PB_SDA; \
1036			else	immr->im_cpm.cp_pbdat &= ~PB_SDA
1037
1038		I2C_SCL(bit)
1039
1040		If <bit> is TRUE, sets the I2C clock line high. If it
1041		is FALSE, it clears it (low).
1042
1043		eg: #define I2C_SCL(bit) \
1044			if(bit) immr->im_cpm.cp_pbdat |=  PB_SCL; \
1045			else	immr->im_cpm.cp_pbdat &= ~PB_SCL
1046
1047		I2C_DELAY
1048
1049		This delay is invoked four times per clock cycle so this
1050		controls the rate of data transfer.  The data rate thus
1051		is 1 / (I2C_DELAY * 4). Often defined to be something
1052		like:
1053
1054		#define I2C_DELAY  udelay(2)
1055
1056		CFG_I2C_INIT_BOARD
1057
1058		When a board is reset during an i2c bus transfer
1059		chips might think that the current transfer is still
1060		in progress. On some boards it is possible to access
1061		the i2c SCLK line directly, either by using the
1062		processor pin as a GPIO or by having a second pin
1063		connected to the bus. If this option is defined a
1064		custom i2c_init_board() routine in boards/xxx/board.c
1065		is run early in the boot sequence.
1066
1067- SPI Support:	CONFIG_SPI
1068
1069		Enables SPI driver (so far only tested with
1070		SPI EEPROM, also an instance works with Crystal A/D and
1071		D/As on the SACSng board)
1072
1073		CONFIG_SPI_X
1074
1075		Enables extended (16-bit) SPI EEPROM addressing.
1076		(symmetrical to CONFIG_I2C_X)
1077
1078		CONFIG_SOFT_SPI
1079
1080		Enables a software (bit-bang) SPI driver rather than
1081		using hardware support. This is a general purpose
1082		driver that only requires three general I/O port pins
1083		(two outputs, one input) to function. If this is
1084		defined, the board configuration must define several
1085		SPI configuration items (port pins to use, etc). For
1086		an example, see include/configs/sacsng.h.
1087
1088- FPGA Support: CONFIG_FPGA_COUNT
1089
1090		Specify the number of FPGA devices to support.
1091
1092		CONFIG_FPGA
1093
1094		Used to specify the types of FPGA devices.  For example,
1095		#define CONFIG_FPGA  CFG_XILINX_VIRTEX2
1096
1097		CFG_FPGA_PROG_FEEDBACK
1098
1099		Enable printing of hash marks during FPGA configuration.
1100
1101		CFG_FPGA_CHECK_BUSY
1102
1103		Enable checks on FPGA configuration interface busy
1104		status by the configuration function. This option
1105		will require a board or device specific function to
1106		be written.
1107
1108		CONFIG_FPGA_DELAY
1109
1110		If defined, a function that provides delays in the FPGA
1111		configuration driver.
1112
1113		CFG_FPGA_CHECK_CTRLC
1114		Allow Control-C to interrupt FPGA configuration
1115
1116		CFG_FPGA_CHECK_ERROR
1117
1118		Check for configuration errors during FPGA bitfile
1119		loading. For example, abort during Virtex II
1120		configuration if the INIT_B line goes low (which
1121		indicated a CRC error).
1122
1123		CFG_FPGA_WAIT_INIT
1124
1125		Maximum time to wait for the INIT_B line to deassert
1126		after PROB_B has been deasserted during a Virtex II
1127		FPGA configuration sequence. The default time is 500
1128		mS.
1129
1130		CFG_FPGA_WAIT_BUSY
1131
1132		Maximum time to wait for BUSY to deassert during
1133		Virtex II FPGA configuration. The default is 5 mS.
1134
1135		CFG_FPGA_WAIT_CONFIG
1136
1137		Time to wait after FPGA configuration. The default is
1138		200 mS.
1139
1140- Configuration Management:
1141		CONFIG_IDENT_STRING
1142
1143		If defined, this string will be added to the U-Boot
1144		version information (U_BOOT_VERSION)
1145
1146- Vendor Parameter Protection:
1147
1148		U-Boot considers the values of the environment
1149		variables "serial#" (Board Serial Number) and
1150		"ethaddr" (Ethernet Address) to be parameters that
1151		are set once by the board vendor / manufacturer, and
1152		protects these variables from casual modification by
1153		the user. Once set, these variables are read-only,
1154		and write or delete attempts are rejected. You can
1155		change this behviour:
1156
1157		If CONFIG_ENV_OVERWRITE is #defined in your config
1158		file, the write protection for vendor parameters is
1159		completely disabled. Anybody can change or delete
1160		these parameters.
1161
1162		Alternatively, if you #define _both_ CONFIG_ETHADDR
1163		_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1164		ethernet address is installed in the environment,
1165		which can be changed exactly ONCE by the user. [The
1166		serial# is unaffected by this, i. e. it remains
1167		read-only.]
1168
1169- Protected RAM:
1170		CONFIG_PRAM
1171
1172		Define this variable to enable the reservation of
1173		"protected RAM", i. e. RAM which is not overwritten
1174		by U-Boot. Define CONFIG_PRAM to hold the number of
1175		kB you want to reserve for pRAM. You can overwrite
1176		this default value by defining an environment
1177		variable "pram" to the number of kB you want to
1178		reserve. Note that the board info structure will
1179		still show the full amount of RAM. If pRAM is
1180		reserved, a new environment variable "mem" will
1181		automatically be defined to hold the amount of
1182		remaining RAM in a form that can be passed as boot
1183		argument to Linux, for instance like that:
1184
1185			setenv bootargs ... mem=\$(mem)
1186			saveenv
1187
1188		This way you can tell Linux not to use this memory,
1189		either, which results in a memory region that will
1190		not be affected by reboots.
1191
1192		*WARNING* If your board configuration uses automatic
1193		detection of the RAM size, you must make sure that
1194		this memory test is non-destructive. So far, the
1195		following board configurations are known to be
1196		"pRAM-clean":
1197
1198			ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1199			HERMES, IP860, RPXlite, LWMON, LANTEC,
1200			PCU_E, FLAGADM, TQM8260
1201
1202- Error Recovery:
1203		CONFIG_PANIC_HANG
1204
1205		Define this variable to stop the system in case of a
1206		fatal error, so that you have to reset it manually.
1207		This is probably NOT a good idea for an embedded
1208		system where you want to system to reboot
1209		automatically as fast as possible, but it may be
1210		useful during development since you can try to debug
1211		the conditions that lead to the situation.
1212
1213		CONFIG_NET_RETRY_COUNT
1214
1215		This variable defines the number of retries for
1216		network operations like ARP, RARP, TFTP, or BOOTP
1217		before giving up the operation. If not defined, a
1218		default value of 5 is used.
1219
1220- Command Interpreter:
1221		CFG_HUSH_PARSER
1222
1223		Define this variable to enable the "hush" shell (from
1224		Busybox) as command line interpreter, thus enabling
1225		powerful command line syntax like
1226		if...then...else...fi conditionals or `&&' and '||'
1227		constructs ("shell scripts").
1228
1229		If undefined, you get the old, much simpler behaviour
1230		with a somewhat smaller memory footprint.
1231
1232
1233		CFG_PROMPT_HUSH_PS2
1234
1235		This defines the secondary prompt string, which is
1236		printed when the command interpreter needs more input
1237		to complete a command. Usually "> ".
1238
1239	Note:
1240
1241		In the current implementation, the local variables
1242		space and global environment variables space are
1243		separated. Local variables are those you define by
1244		simply typing `name=value'. To access a local
1245		variable later on, you have write `$name' or
1246		`${name}'; to execute the contents of a variable
1247		directly type `$name' at the command prompt.
1248
1249		Global environment variables are those you use
1250		setenv/printenv to work with. To run a command stored
1251		in such a variable, you need to use the run command,
1252		and you must not use the '$' sign to access them.
1253
1254		To store commands and special characters in a
1255		variable, please use double quotation marks
1256		surrounding the whole text of the variable, instead
1257		of the backslashes before semicolons and special
1258		symbols.
1259
1260- Default Environment:
1261		CONFIG_EXTRA_ENV_SETTINGS
1262
1263		Define this to contain any number of null terminated
1264		strings (variable = value pairs) that will be part of
1265		the default environment compiled into the boot image.
1266
1267		For example, place something like this in your
1268		board's config file:
1269
1270		#define CONFIG_EXTRA_ENV_SETTINGS \
1271			"myvar1=value1\0" \
1272			"myvar2=value2\0"
1273
1274		Warning: This method is based on knowledge about the
1275		internal format how the environment is stored by the
1276		U-Boot code. This is NOT an official, exported
1277		interface! Although it is unlikely that this format
1278		will change soon, there is no guarantee either.
1279		You better know what you are doing here.
1280
1281		Note: overly (ab)use of the default environment is
1282		discouraged. Make sure to check other ways to preset
1283		the environment like the autoscript function or the
1284		boot command first.
1285
1286- DataFlash Support:
1287		CONFIG_HAS_DATAFLASH
1288
1289		Defining this option enables DataFlash features and
1290		allows to read/write in Dataflash via the standard
1291		commands cp, md...
1292
1293- SystemACE Support:
1294		CONFIG_SYSTEMACE
1295
1296		Adding this option adds support for Xilinx SystemACE
1297		chips attached via some sort of local bus. The address
1298		of the chip must alsh be defined in the
1299		CFG_SYSTEMACE_BASE macro. For example:
1300
1301		#define CONFIG_SYSTEMACE
1302		#define CFG_SYSTEMACE_BASE 0xf0000000
1303
1304		When SystemACE support is added, the "ace" device type
1305		becomes available to the fat commands, i.e. fatls.
1306
1307- Show boot progress:
1308		CONFIG_SHOW_BOOT_PROGRESS
1309
1310		Defining this option allows to add some board-
1311		specific code (calling a user-provided function
1312		"show_boot_progress(int)") that enables you to show
1313		the system's boot progress on some display (for
1314		example, some LED's) on your board. At the moment,
1315		the following checkpoints are implemented:
1316
1317  Arg	Where			When
1318    1	common/cmd_bootm.c	before attempting to boot an image
1319   -1	common/cmd_bootm.c	Image header has bad	 magic number
1320    2	common/cmd_bootm.c	Image header has correct magic number
1321   -2	common/cmd_bootm.c	Image header has bad	 checksum
1322    3	common/cmd_bootm.c	Image header has correct checksum
1323   -3	common/cmd_bootm.c	Image data   has bad	 checksum
1324    4	common/cmd_bootm.c	Image data   has correct checksum
1325   -4	common/cmd_bootm.c	Image is for unsupported architecture
1326    5	common/cmd_bootm.c	Architecture check OK
1327   -5	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1328    6	common/cmd_bootm.c	Image Type check OK
1329   -6	common/cmd_bootm.c	gunzip uncompression error
1330   -7	common/cmd_bootm.c	Unimplemented compression type
1331    7	common/cmd_bootm.c	Uncompression OK
1332   -8	common/cmd_bootm.c	Wrong Image Type (not kernel, multi, standalone)
1333    8	common/cmd_bootm.c	Image Type check OK
1334   -9	common/cmd_bootm.c	Unsupported OS (not Linux, BSD, VxWorks, QNX)
1335    9	common/cmd_bootm.c	Start initial ramdisk verification
1336  -10	common/cmd_bootm.c	Ramdisk header has bad	   magic number
1337  -11	common/cmd_bootm.c	Ramdisk header has bad	   checksum
1338   10	common/cmd_bootm.c	Ramdisk header is OK
1339  -12	common/cmd_bootm.c	Ramdisk data   has bad	   checksum
1340   11	common/cmd_bootm.c	Ramdisk data   has correct checksum
1341   12	common/cmd_bootm.c	Ramdisk verification complete, start loading
1342  -13	common/cmd_bootm.c	Wrong Image Type (not PPC Linux Ramdisk)
1343   13	common/cmd_bootm.c	Start multifile image verification
1344   14	common/cmd_bootm.c	No initial ramdisk, no multifile, continue.
1345   15	common/cmd_bootm.c	All preparation done, transferring control to OS
1346
1347  -30	lib_ppc/board.c		Fatal error, hang the system
1348  -31	post/post.c		POST test failed, detected by post_output_backlog()
1349  -32	post/post.c		POST test failed, detected by post_run_single()
1350
1351   -1	common/cmd_doc.c	Bad usage of "doc" command
1352   -1	common/cmd_doc.c	No boot device
1353   -1	common/cmd_doc.c	Unknown Chip ID on boot device
1354   -1	common/cmd_doc.c	Read Error on boot device
1355   -1	common/cmd_doc.c	Image header has bad magic number
1356
1357   -1	common/cmd_ide.c	Bad usage of "ide" command
1358   -1	common/cmd_ide.c	No boot device
1359   -1	common/cmd_ide.c	Unknown boot device
1360   -1	common/cmd_ide.c	Unknown partition table
1361   -1	common/cmd_ide.c	Invalid partition type
1362   -1	common/cmd_ide.c	Read Error on boot device
1363   -1	common/cmd_ide.c	Image header has bad magic number
1364
1365   -1	common/cmd_nand.c	Bad usage of "nand" command
1366   -1	common/cmd_nand.c	No boot device
1367   -1	common/cmd_nand.c	Unknown Chip ID on boot device
1368   -1	common/cmd_nand.c	Read Error on boot device
1369   -1	common/cmd_nand.c	Image header has bad magic number
1370
1371   -1	common/env_common.c	Environment has a bad CRC, using default
1372
1373
1374Modem Support:
1375--------------
1376
1377[so far only for SMDK2400 and TRAB boards]
1378
1379- Modem support endable:
1380		CONFIG_MODEM_SUPPORT
1381
1382- RTS/CTS Flow control enable:
1383		CONFIG_HWFLOW
1384
1385- Modem debug support:
1386		CONFIG_MODEM_SUPPORT_DEBUG
1387
1388		Enables debugging stuff (char screen[1024], dbg())
1389		for modem support. Useful only with BDI2000.
1390
1391- Interrupt support (PPC):
1392
1393		There are common interrupt_init() and timer_interrupt()
1394		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1395		for cpu specific initialization. interrupt_init_cpu()
1396		should set decrementer_count to appropriate value. If
1397		cpu resets decrementer automatically after interrupt
1398		(ppc4xx) it should set decrementer_count to zero.
1399		timer_interrupt() calls timer_interrupt_cpu() for cpu
1400		specific handling. If board has watchdog / status_led
1401		/ other_activity_monitor it works automatically from
1402		general timer_interrupt().
1403
1404- General:
1405
1406		In the target system modem support is enabled when a
1407		specific key (key combination) is pressed during
1408		power-on. Otherwise U-Boot will boot normally
1409		(autoboot). The key_pressed() fuction is called from
1410		board_init(). Currently key_pressed() is a dummy
1411		function, returning 1 and thus enabling modem
1412		initialization.
1413
1414		If there are no modem init strings in the
1415		environment, U-Boot proceed to autoboot; the
1416		previous output (banner, info printfs) will be
1417		supressed, though.
1418
1419		See also: doc/README.Modem
1420
1421
1422Configuration Settings:
1423-----------------------
1424
1425- CFG_LONGHELP: Defined when you want long help messages included;
1426		undefine this when you're short of memory.
1427
1428- CFG_PROMPT:	This is what U-Boot prints on the console to
1429		prompt for user input.
1430
1431- CFG_CBSIZE:	Buffer size for input from the Console
1432
1433- CFG_PBSIZE:	Buffer size for Console output
1434
1435- CFG_MAXARGS:	max. Number of arguments accepted for monitor commands
1436
1437- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1438		the application (usually a Linux kernel) when it is
1439		booted
1440
1441- CFG_BAUDRATE_TABLE:
1442		List of legal baudrate settings for this board.
1443
1444- CFG_CONSOLE_INFO_QUIET
1445		Suppress display of console information at boot.
1446
1447- CFG_CONSOLE_IS_IN_ENV
1448		If the board specific function
1449			extern int overwrite_console (void);
1450		returns 1, the stdin, stderr and stdout are switched to the
1451		serial port, else the settings in the environment are used.
1452
1453- CFG_CONSOLE_OVERWRITE_ROUTINE
1454		Enable the call to overwrite_console().
1455
1456- CFG_CONSOLE_ENV_OVERWRITE
1457		Enable overwrite of previous console environment settings.
1458
1459- CFG_MEMTEST_START, CFG_MEMTEST_END:
1460		Begin and End addresses of the area used by the
1461		simple memory test.
1462
1463- CFG_ALT_MEMTEST:
1464		Enable an alternate, more extensive memory test.
1465
1466- CFG_MEMTEST_SCRATCH:
1467		Scratch address used by the alternate memory test
1468		You only need to set this if address zero isn't writeable
1469
1470- CFG_TFTP_LOADADDR:
1471		Default load address for network file downloads
1472
1473- CFG_LOADS_BAUD_CHANGE:
1474		Enable temporary baudrate change while serial download
1475
1476- CFG_SDRAM_BASE:
1477		Physical start address of SDRAM. _Must_ be 0 here.
1478
1479- CFG_MBIO_BASE:
1480		Physical start address of Motherboard I/O (if using a
1481		Cogent motherboard)
1482
1483- CFG_FLASH_BASE:
1484		Physical start address of Flash memory.
1485
1486- CFG_MONITOR_BASE:
1487		Physical start address of boot monitor code (set by
1488		make config files to be same as the text base address
1489		(TEXT_BASE) used when linking) - same as
1490		CFG_FLASH_BASE when booting from flash.
1491
1492- CFG_MONITOR_LEN:
1493		Size of memory reserved for monitor code, used to
1494		determine _at_compile_time_ (!) if the environment is
1495		embedded within the U-Boot image, or in a separate
1496		flash sector.
1497
1498- CFG_MALLOC_LEN:
1499		Size of DRAM reserved for malloc() use.
1500
1501- CFG_BOOTMAPSZ:
1502		Maximum size of memory mapped by the startup code of
1503		the Linux kernel; all data that must be processed by
1504		the Linux kernel (bd_info, boot arguments, eventually
1505		initrd image) must be put below this limit.
1506
1507- CFG_MAX_FLASH_BANKS:
1508		Max number of Flash memory banks
1509
1510- CFG_MAX_FLASH_SECT:
1511		Max number of sectors on a Flash chip
1512
1513- CFG_FLASH_ERASE_TOUT:
1514		Timeout for Flash erase operations (in ms)
1515
1516- CFG_FLASH_WRITE_TOUT:
1517		Timeout for Flash write operations (in ms)
1518
1519- CFG_FLASH_LOCK_TOUT
1520		Timeout for Flash set sector lock bit operation (in ms)
1521
1522- CFG_FLASH_UNLOCK_TOUT
1523		Timeout for Flash clear lock bits operation (in ms)
1524
1525- CFG_FLASH_PROTECTION
1526		If defined, hardware flash sectors protection is used
1527		instead of U-Boot software protection.
1528
1529- CFG_DIRECT_FLASH_TFTP:
1530
1531		Enable TFTP transfers directly to flash memory;
1532		without this option such a download has to be
1533		performed in two steps: (1) download to RAM, and (2)
1534		copy from RAM to flash.
1535
1536		The two-step approach is usually more reliable, since
1537		you can check if the download worked before you erase
1538		the flash, but in some situations (when sytem RAM is
1539		too limited to allow for a tempory copy of the
1540		downloaded image) this option may be very useful.
1541
1542- CFG_FLASH_CFI:
1543		Define if the flash driver uses extra elements in the
1544		common flash structure for storing flash geometry.
1545
1546- CFG_FLASH_CFI_DRIVER
1547		This option also enables the building of the cfi_flash driver
1548		in the drivers directory
1549
1550- CFG_RX_ETH_BUFFER:
1551		Defines the number of ethernet receive buffers. On some
1552		ethernet controllers it is recommended to set this value
1553		to 8 or even higher (EEPRO100 or 405 EMAC), since all
1554		buffers can be full shortly after enabling the interface
1555		on high ethernet traffic.
1556		Defaults to 4 if not defined.
1557
1558The following definitions that deal with the placement and management
1559of environment data (variable area); in general, we support the
1560following configurations:
1561
1562- CFG_ENV_IS_IN_FLASH:
1563
1564	Define this if the environment is in flash memory.
1565
1566	a) The environment occupies one whole flash sector, which is
1567	   "embedded" in the text segment with the U-Boot code. This
1568	   happens usually with "bottom boot sector" or "top boot
1569	   sector" type flash chips, which have several smaller
1570	   sectors at the start or the end. For instance, such a
1571	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1572	   such a case you would place the environment in one of the
1573	   4 kB sectors - with U-Boot code before and after it. With
1574	   "top boot sector" type flash chips, you would put the
1575	   environment in one of the last sectors, leaving a gap
1576	   between U-Boot and the environment.
1577
1578	- CFG_ENV_OFFSET:
1579
1580	   Offset of environment data (variable area) to the
1581	   beginning of flash memory; for instance, with bottom boot
1582	   type flash chips the second sector can be used: the offset
1583	   for this sector is given here.
1584
1585	   CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1586
1587	- CFG_ENV_ADDR:
1588
1589	   This is just another way to specify the start address of
1590	   the flash sector containing the environment (instead of
1591	   CFG_ENV_OFFSET).
1592
1593	- CFG_ENV_SECT_SIZE:
1594
1595	   Size of the sector containing the environment.
1596
1597
1598	b) Sometimes flash chips have few, equal sized, BIG sectors.
1599	   In such a case you don't want to spend a whole sector for
1600	   the environment.
1601
1602	- CFG_ENV_SIZE:
1603
1604	   If you use this in combination with CFG_ENV_IS_IN_FLASH
1605	   and CFG_ENV_SECT_SIZE, you can specify to use only a part
1606	   of this flash sector for the environment. This saves
1607	   memory for the RAM copy of the environment.
1608
1609	   It may also save flash memory if you decide to use this
1610	   when your environment is "embedded" within U-Boot code,
1611	   since then the remainder of the flash sector could be used
1612	   for U-Boot code. It should be pointed out that this is
1613	   STRONGLY DISCOURAGED from a robustness point of view:
1614	   updating the environment in flash makes it always
1615	   necessary to erase the WHOLE sector. If something goes
1616	   wrong before the contents has been restored from a copy in
1617	   RAM, your target system will be dead.
1618
1619	- CFG_ENV_ADDR_REDUND
1620	  CFG_ENV_SIZE_REDUND
1621
1622	   These settings describe a second storage area used to hold
1623	   a redundand copy of the environment data, so that there is
1624	   a valid backup copy in case there is a power failure during
1625	   a "saveenv" operation.
1626
1627BE CAREFUL! Any changes to the flash layout, and some changes to the
1628source code will make it necessary to adapt <board>/u-boot.lds*
1629accordingly!
1630
1631
1632- CFG_ENV_IS_IN_NVRAM:
1633
1634	Define this if you have some non-volatile memory device
1635	(NVRAM, battery buffered SRAM) which you want to use for the
1636	environment.
1637
1638	- CFG_ENV_ADDR:
1639	- CFG_ENV_SIZE:
1640
1641	  These two #defines are used to determin the memory area you
1642	  want to use for environment. It is assumed that this memory
1643	  can just be read and written to, without any special
1644	  provision.
1645
1646BE CAREFUL! The first access to the environment happens quite early
1647in U-Boot initalization (when we try to get the setting of for the
1648console baudrate). You *MUST* have mappend your NVRAM area then, or
1649U-Boot will hang.
1650
1651Please note that even with NVRAM we still use a copy of the
1652environment in RAM: we could work on NVRAM directly, but we want to
1653keep settings there always unmodified except somebody uses "saveenv"
1654to save the current settings.
1655
1656
1657- CFG_ENV_IS_IN_EEPROM:
1658
1659	Use this if you have an EEPROM or similar serial access
1660	device and a driver for it.
1661
1662	- CFG_ENV_OFFSET:
1663	- CFG_ENV_SIZE:
1664
1665	  These two #defines specify the offset and size of the
1666	  environment area within the total memory of your EEPROM.
1667
1668	- CFG_I2C_EEPROM_ADDR:
1669	  If defined, specified the chip address of the EEPROM device.
1670	  The default address is zero.
1671
1672	- CFG_EEPROM_PAGE_WRITE_BITS:
1673	  If defined, the number of bits used to address bytes in a
1674	  single page in the EEPROM device.  A 64 byte page, for example
1675	  would require six bits.
1676
1677	- CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1678	  If defined, the number of milliseconds to delay between
1679	  page writes.	The default is zero milliseconds.
1680
1681	- CFG_I2C_EEPROM_ADDR_LEN:
1682	  The length in bytes of the EEPROM memory array address.  Note
1683	  that this is NOT the chip address length!
1684
1685	- CFG_EEPROM_SIZE:
1686	  The size in bytes of the EEPROM device.
1687
1688
1689- CFG_ENV_IS_IN_DATAFLASH:
1690
1691	Define this if you have a DataFlash memory device which you
1692	want to use for the environment.
1693
1694	- CFG_ENV_OFFSET:
1695	- CFG_ENV_ADDR:
1696	- CFG_ENV_SIZE:
1697
1698	  These three #defines specify the offset and size of the
1699	  environment area within the total memory of your DataFlash placed
1700	  at the specified address.
1701
1702
1703- CFG_SPI_INIT_OFFSET
1704
1705	Defines offset to the initial SPI buffer area in DPRAM. The
1706	area is used at an early stage (ROM part) if the environment
1707	is configured to reside in the SPI EEPROM: We need a 520 byte
1708	scratch DPRAM area. It is used between the two initialization
1709	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1710	to be a good choice since it makes it far enough from the
1711	start of the data area as well as from the stack pointer.
1712
1713Please note that the environment is read-only as long as the monitor
1714has been relocated to RAM and a RAM copy of the environment has been
1715created; also, when using EEPROM you will have to use getenv_r()
1716until then to read environment variables.
1717
1718The environment is protected by a CRC32 checksum. Before the monitor
1719is relocated into RAM, as a result of a bad CRC you will be working
1720with the compiled-in default environment - *silently*!!! [This is
1721necessary, because the first environment variable we need is the
1722"baudrate" setting for the console - if we have a bad CRC, we don't
1723have any device yet where we could complain.]
1724
1725Note: once the monitor has been relocated, then it will complain if
1726the default environment is used; a new CRC is computed as soon as you
1727use the "saveenv" command to store a valid environment.
1728
1729- CFG_FAULT_ECHO_LINK_DOWN:
1730		Echo the inverted Ethernet link state to the fault LED.
1731
1732		Note: If this option is active, then CFG_FAULT_MII_ADDR
1733		      also needs to be defined.
1734
1735- CFG_FAULT_MII_ADDR:
1736		MII address of the PHY to check for the Ethernet link state.
1737
1738- CFG_64BIT_VSPRINTF:
1739		Makes vsprintf (and all *printf functions) support printing
1740		of 64bit values by using the L quantifier
1741
1742- CFG_64BIT_STRTOUL:
1743		Adds simple_strtoull that returns a 64bit value
1744
1745Low Level (hardware related) configuration options:
1746---------------------------------------------------
1747
1748- CFG_CACHELINE_SIZE:
1749		Cache Line Size of the CPU.
1750
1751- CFG_DEFAULT_IMMR:
1752		Default address of the IMMR after system reset.
1753
1754		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1755		and RPXsuper) to be able to adjust the position of
1756		the IMMR register after a reset.
1757
1758- Floppy Disk Support:
1759		CFG_FDC_DRIVE_NUMBER
1760
1761		the default drive number (default value 0)
1762
1763		CFG_ISA_IO_STRIDE
1764
1765		defines the spacing between fdc chipset registers
1766		(default value 1)
1767
1768		CFG_ISA_IO_OFFSET
1769
1770		defines the offset of register from address. It
1771		depends on which part of the data bus is connected to
1772		the fdc chipset. (default value 0)
1773
1774		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1775		CFG_FDC_DRIVE_NUMBER are undefined, they take their
1776		default value.
1777
1778		if CFG_FDC_HW_INIT is defined, then the function
1779		fdc_hw_init() is called at the beginning of the FDC
1780		setup. fdc_hw_init() must be provided by the board
1781		source code. It is used to make hardware dependant
1782		initializations.
1783
1784- CFG_IMMR:	Physical address of the Internal Memory Mapped
1785		Register; DO NOT CHANGE! (11-4)
1786		[MPC8xx systems only]
1787
1788- CFG_INIT_RAM_ADDR:
1789
1790		Start address of memory area that can be used for
1791		initial data and stack; please note that this must be
1792		writable memory that is working WITHOUT special
1793		initialization, i. e. you CANNOT use normal RAM which
1794		will become available only after programming the
1795		memory controller and running certain initialization
1796		sequences.
1797
1798		U-Boot uses the following memory types:
1799		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1800		- MPC824X: data cache
1801		- PPC4xx:  data cache
1802
1803- CFG_GBL_DATA_OFFSET:
1804
1805		Offset of the initial data structure in the memory
1806		area defined by CFG_INIT_RAM_ADDR. Usually
1807		CFG_GBL_DATA_OFFSET is chosen such that the initial
1808		data is located at the end of the available space
1809		(sometimes written as (CFG_INIT_RAM_END -
1810		CFG_INIT_DATA_SIZE), and the initial stack is just
1811		below that area (growing from (CFG_INIT_RAM_ADDR +
1812		CFG_GBL_DATA_OFFSET) downward.
1813
1814	Note:
1815		On the MPC824X (or other systems that use the data
1816		cache for initial memory) the address chosen for
1817		CFG_INIT_RAM_ADDR is basically arbitrary - it must
1818		point to an otherwise UNUSED address space between
1819		the top of RAM and the start of the PCI space.
1820
1821- CFG_SIUMCR:	SIU Module Configuration (11-6)
1822
1823- CFG_SYPCR:	System Protection Control (11-9)
1824
1825- CFG_TBSCR:	Time Base Status and Control (11-26)
1826
1827- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)
1828
1829- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)
1830
1831- CFG_SCCR:	System Clock and reset Control Register (15-27)
1832
1833- CFG_OR_TIMING_SDRAM:
1834		SDRAM timing
1835
1836- CFG_MAMR_PTA:
1837		periodic timer for refresh
1838
1839- CFG_DER:	Debug Event Register (37-47)
1840
1841- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1842  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1843  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1844  CFG_BR1_PRELIM:
1845		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1846
1847- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1848  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1849  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1850		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1851
1852- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1853  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1854		Machine Mode Register and Memory Periodic Timer
1855		Prescaler definitions (SDRAM timing)
1856
1857- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1858		enable I2C microcode relocation patch (MPC8xx);
1859		define relocation offset in DPRAM [DSP2]
1860
1861- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1862		enable SPI microcode relocation patch (MPC8xx);
1863		define relocation offset in DPRAM [SCC4]
1864
1865- CFG_USE_OSCCLK:
1866		Use OSCM clock mode on MBX8xx board. Be careful,
1867		wrong setting might damage your board. Read
1868		doc/README.MBX before setting this variable!
1869
1870- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1871		Offset of the bootmode word in DPRAM used by post
1872		(Power On Self Tests). This definition overrides
1873		#define'd default value in commproc.h resp.
1874		cpm_8260.h.
1875
1876- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1877  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1878  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1879  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1880  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1881  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1882  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1883  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1884		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1885
1886Building the Software:
1887======================
1888
1889Building U-Boot has been tested in native PPC environments (on a
1890PowerBook G3 running LinuxPPC 2000) and in cross environments
1891(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1892NetBSD 1.5 on x86).
1893
1894If you are not using a native PPC environment, it is assumed that you
1895have the GNU cross compiling tools available in your path and named
1896with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1897you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1898the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1899change it to:
1900
1901	CROSS_COMPILE = ppc_4xx-
1902
1903
1904U-Boot is intended to be  simple  to  build.  After  installing	 the
1905sources	 you must configure U-Boot for one specific board type. This
1906is done by typing:
1907
1908	make NAME_config
1909
1910where "NAME_config" is the name of one of the existing
1911configurations; the following names are supported:
1912
1913    ADCIOP_config	  GTH_config		TQM850L_config
1914    ADS860_config	  IP860_config		TQM855L_config
1915    AR405_config	  IVML24_config		TQM860L_config
1916    CANBT_config	  IVMS8_config		WALNUT405_config
1917    CPCI405_config	  LANTEC_config		cogent_common_config
1918    CPCIISER4_config	  MBX_config		cogent_mpc8260_config
1919    CU824_config	  MBX860T_config	cogent_mpc8xx_config
1920    ESTEEM192E_config	  RPXlite_config	hermes_config
1921    ETX094_config	  RPXsuper_config	hymod_config
1922    FADS823_config	  SM850_config		lwmon_config
1923    FADS850SAR_config	  SPD823TS_config	pcu_e_config
1924    FADS860T_config	  SXNI855T_config	rsdproto_config
1925    FPS850L_config	  Sandpoint8240_config	sbc8260_config
1926    GENIETV_config	  TQM823L_config	PIP405_config
1927    GEN860T_config	  EBONY_config		FPS860L_config
1928    ELPT860_config	  cmi_mpc5xx_config	NETVIA_config
1929    at91rm9200dk_config	  omap1510inn_config	MPC8260ADS_config
1930    omap1610inn_config	  ZPC1900_config	MPC8540ADS_config
1931    MPC8560ADS_config	  QS850_config		QS823_config
1932    QS860T_config	  DUET_ADS_config	omap1610h2_config
1933
1934Note: for some board special configuration names may exist; check  if
1935      additional  information is available from the board vendor; for
1936      instance, the TQM8xxL systems run normally at 50 MHz and use  a
1937      SCC  for	10baseT	 ethernet; there are also systems with 80 MHz
1938      CPU clock, and an optional Fast Ethernet	module	is  available
1939      for  CPU's  with FEC. You can select such additional "features"
1940      when chosing the configuration, i. e.
1941
1942      make TQM860L_config
1943	- will configure for a plain TQM860L, i. e. 50MHz, no FEC
1944
1945      make TQM860L_FEC_config
1946	- will configure for a TQM860L at 50MHz with FEC for ethernet
1947
1948      make TQM860L_80MHz_config
1949	- will configure for a TQM860L at 80 MHz, with normal 10baseT
1950	  interface
1951
1952      make TQM860L_FEC_80MHz_config
1953	- will configure for a TQM860L at 80 MHz with FEC for ethernet
1954
1955      make TQM823L_LCD_config
1956	- will configure for a TQM823L with U-Boot console on LCD
1957
1958      make TQM823L_LCD_80MHz_config
1959	- will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1960
1961      etc.
1962
1963
1964Finally, type "make all", and you should get some working U-Boot
1965images ready for download to / installation on your system:
1966
1967- "u-boot.bin" is a raw binary image
1968- "u-boot" is an image in ELF binary format
1969- "u-boot.srec" is in Motorola S-Record format
1970
1971
1972Please be aware that the Makefiles assume you are using GNU make, so
1973for instance on NetBSD you might need to use "gmake" instead of
1974native "make".
1975
1976
1977If the system board that you have is not listed, then you will need
1978to port U-Boot to your hardware platform. To do this, follow these
1979steps:
1980
19811.  Add a new configuration option for your board to the toplevel
1982    "Makefile" and to the "MAKEALL" script, using the existing
1983    entries as examples. Note that here and at many other places
1984    boards and other names are listed in alphabetical sort order. Please
1985    keep this order.
19862.  Create a new directory to hold your board specific code. Add any
1987    files you need. In your board directory, you will need at least
1988    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
19893.  Create a new configuration file "include/configs/<board>.h" for
1990    your board
19913.  If you're porting U-Boot to a new CPU, then also create a new
1992    directory to hold your CPU specific code. Add any files you need.
19934.  Run "make <board>_config" with your new name.
19945.  Type "make", and you should get a working "u-boot.srec" file
1995    to be installed on your target system.
19966.  Debug and solve any problems that might arise.
1997    [Of course, this last step is much harder than it sounds.]
1998
1999
2000Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2001==============================================================
2002
2003If you have modified U-Boot sources (for instance added a new	board
2004or  support  for  new  devices,	 a new CPU, etc.) you are expected to
2005provide feedback to the other developers. The feedback normally takes
2006the form of a "patch", i. e. a context diff against a certain (latest
2007official or latest in CVS) version of U-Boot sources.
2008
2009But before you submit such a patch, please verify that	your  modifi-
2010cation	did not break existing code. At least make sure that *ALL* of
2011the supported boards compile WITHOUT ANY compiler warnings. To do so,
2012just run the "MAKEALL" script, which will configure and build U-Boot
2013for ALL supported system. Be warned, this will take a while. You  can
2014select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
2015environment variable to the script, i. e. to use the cross tools from
2016MontaVista's Hard Hat Linux you can type
2017
2018	CROSS_COMPILE=ppc_8xx- MAKEALL
2019
2020or to build on a native PowerPC system you can type
2021
2022	CROSS_COMPILE=' ' MAKEALL
2023
2024See also "U-Boot Porting Guide" below.
2025
2026
2027Monitor Commands - Overview:
2028============================
2029
2030go	- start application at address 'addr'
2031run	- run commands in an environment variable
2032bootm	- boot application image from memory
2033bootp	- boot image via network using BootP/TFTP protocol
2034tftpboot- boot image via network using TFTP protocol
2035	       and env variables "ipaddr" and "serverip"
2036	       (and eventually "gatewayip")
2037rarpboot- boot image via network using RARP/TFTP protocol
2038diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
2039loads	- load S-Record file over serial line
2040loadb	- load binary file over serial line (kermit mode)
2041md	- memory display
2042mm	- memory modify (auto-incrementing)
2043nm	- memory modify (constant address)
2044mw	- memory write (fill)
2045cp	- memory copy
2046cmp	- memory compare
2047crc32	- checksum calculation
2048imd	- i2c memory display
2049imm	- i2c memory modify (auto-incrementing)
2050inm	- i2c memory modify (constant address)
2051imw	- i2c memory write (fill)
2052icrc32	- i2c checksum calculation
2053iprobe	- probe to discover valid I2C chip addresses
2054iloop	- infinite loop on address range
2055isdram	- print SDRAM configuration information
2056sspi	- SPI utility commands
2057base	- print or set address offset
2058printenv- print environment variables
2059setenv	- set environment variables
2060saveenv - save environment variables to persistent storage
2061protect - enable or disable FLASH write protection
2062erase	- erase FLASH memory
2063flinfo	- print FLASH memory information
2064bdinfo	- print Board Info structure
2065iminfo	- print header information for application image
2066coninfo - print console devices and informations
2067ide	- IDE sub-system
2068loop	- infinite loop on address range
2069mtest	- simple RAM test
2070icache	- enable or disable instruction cache
2071dcache	- enable or disable data cache
2072reset	- Perform RESET of the CPU
2073echo	- echo args to console
2074version - print monitor version
2075help	- print online help
2076?	- alias for 'help'
2077
2078
2079Monitor Commands - Detailed Description:
2080========================================
2081
2082TODO.
2083
2084For now: just type "help <command>".
2085
2086
2087Environment Variables:
2088======================
2089
2090U-Boot supports user configuration using Environment Variables which
2091can be made persistent by saving to Flash memory.
2092
2093Environment Variables are set using "setenv", printed using
2094"printenv", and saved to Flash using "saveenv". Using "setenv"
2095without a value can be used to delete a variable from the
2096environment. As long as you don't save the environment you are
2097working with an in-memory copy. In case the Flash area containing the
2098environment is erased by accident, a default environment is provided.
2099
2100Some configuration options can be set using Environment Variables:
2101
2102  baudrate	- see CONFIG_BAUDRATE
2103
2104  bootdelay	- see CONFIG_BOOTDELAY
2105
2106  bootcmd	- see CONFIG_BOOTCOMMAND
2107
2108  bootargs	- Boot arguments when booting an RTOS image
2109
2110  bootfile	- Name of the image to load with TFTP
2111
2112  autoload	- if set to "no" (any string beginning with 'n'),
2113		  "bootp" will just load perform a lookup of the
2114		  configuration from the BOOTP server, but not try to
2115		  load any image using TFTP
2116
2117  autostart	- if set to "yes", an image loaded using the "bootp",
2118		  "rarpboot", "tftpboot" or "diskboot" commands will
2119		  be automatically started (by internally calling
2120		  "bootm")
2121
2122		  If set to "no", a standalone image passed to the
2123		  "bootm" command will be copied to the load address
2124		  (and eventually uncompressed), but NOT be started.
2125		  This can be used to load and uncompress arbitrary
2126		  data.
2127
2128  initrd_high	- restrict positioning of initrd images:
2129		  If this variable is not set, initrd images will be
2130		  copied to the highest possible address in RAM; this
2131		  is usually what you want since it allows for
2132		  maximum initrd size. If for some reason you want to
2133		  make sure that the initrd image is loaded below the
2134		  CFG_BOOTMAPSZ limit, you can set this environment
2135		  variable to a value of "no" or "off" or "0".
2136		  Alternatively, you can set it to a maximum upper
2137		  address to use (U-Boot will still check that it
2138		  does not overwrite the U-Boot stack and data).
2139
2140		  For instance, when you have a system with 16 MB
2141		  RAM, and want to reserve 4 MB from use by Linux,
2142		  you can do this by adding "mem=12M" to the value of
2143		  the "bootargs" variable. However, now you must make
2144		  sure that the initrd image is placed in the first
2145		  12 MB as well - this can be done with
2146
2147		  setenv initrd_high 00c00000
2148
2149		  If you set initrd_high to 0xFFFFFFFF, this is an
2150		  indication to U-Boot that all addresses are legal
2151		  for the Linux kernel, including addresses in flash
2152		  memory. In this case U-Boot will NOT COPY the
2153		  ramdisk at all. This may be useful to reduce the
2154		  boot time on your system, but requires that this
2155		  feature is supported by your Linux kernel.
2156
2157  ipaddr	- IP address; needed for tftpboot command
2158
2159  loadaddr	- Default load address for commands like "bootp",
2160		  "rarpboot", "tftpboot", "loadb" or "diskboot"
2161
2162  loads_echo	- see CONFIG_LOADS_ECHO
2163
2164  serverip	- TFTP server IP address; needed for tftpboot command
2165
2166  bootretry	- see CONFIG_BOOT_RETRY_TIME
2167
2168  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR
2169
2170  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR
2171
2172
2173The following environment variables may be used and automatically
2174updated by the network boot commands ("bootp" and "rarpboot"),
2175depending the information provided by your boot server:
2176
2177  bootfile	- see above
2178  dnsip		- IP address of your Domain Name Server
2179  dnsip2	- IP address of your secondary Domain Name Server
2180  gatewayip	- IP address of the Gateway (Router) to use
2181  hostname	- Target hostname
2182  ipaddr	- see above
2183  netmask	- Subnet Mask
2184  rootpath	- Pathname of the root filesystem on the NFS server
2185  serverip	- see above
2186
2187
2188There are two special Environment Variables:
2189
2190  serial#	- contains hardware identification information such
2191		  as type string and/or serial number
2192  ethaddr	- Ethernet address
2193
2194These variables can be set only once (usually during manufacturing of
2195the board). U-Boot refuses to delete or overwrite these variables
2196once they have been set once.
2197
2198
2199Further special Environment Variables:
2200
2201  ver		- Contains the U-Boot version string as printed
2202		  with the "version" command. This variable is
2203		  readonly (see CONFIG_VERSION_VARIABLE).
2204
2205
2206Please note that changes to some configuration parameters may take
2207only effect after the next boot (yes, that's just like Windoze :-).
2208
2209
2210Command Line Parsing:
2211=====================
2212
2213There are two different command line parsers available with U-Boot:
2214the old "simple" one, and the much more powerful "hush" shell:
2215
2216Old, simple command line parser:
2217--------------------------------
2218
2219- supports environment variables (through setenv / saveenv commands)
2220- several commands on one line, separated by ';'
2221- variable substitution using "... $(name) ..." syntax
2222- special characters ('$', ';') can be escaped by prefixing with '\',
2223  for example:
2224	setenv bootcmd bootm \$(address)
2225- You can also escape text by enclosing in single apostrophes, for example:
2226	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2227
2228Hush shell:
2229-----------
2230
2231- similar to Bourne shell, with control structures like
2232  if...then...else...fi, for...do...done; while...do...done,
2233  until...do...done, ...
2234- supports environment ("global") variables (through setenv / saveenv
2235  commands) and local shell variables (through standard shell syntax
2236  "name=value"); only environment variables can be used with "run"
2237  command
2238
2239General rules:
2240--------------
2241
2242(1) If a command line (or an environment variable executed by a "run"
2243    command) contains several commands separated by semicolon, and
2244    one of these commands fails, then the remaining commands will be
2245    executed anyway.
2246
2247(2) If you execute several variables with one call to run (i. e.
2248    calling run with a list af variables as arguments), any failing
2249    command will cause "run" to terminate, i. e. the remaining
2250    variables are not executed.
2251
2252Note for Redundant Ethernet Interfaces:
2253=======================================
2254
2255Some boards come with redundant ethernet interfaces; U-Boot supports
2256such configurations and is capable of automatic selection of a
2257"working" interface when needed. MAC assignment works as follows:
2258
2259Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2260MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2261"eth1addr" (=>eth1), "eth2addr", ...
2262
2263If the network interface stores some valid MAC address (for instance
2264in SROM), this is used as default address if there is NO correspon-
2265ding setting in the environment; if the corresponding environment
2266variable is set, this overrides the settings in the card; that means:
2267
2268o If the SROM has a valid MAC address, and there is no address in the
2269  environment, the SROM's address is used.
2270
2271o If there is no valid address in the SROM, and a definition in the
2272  environment exists, then the value from the environment variable is
2273  used.
2274
2275o If both the SROM and the environment contain a MAC address, and
2276  both addresses are the same, this MAC address is used.
2277
2278o If both the SROM and the environment contain a MAC address, and the
2279  addresses differ, the value from the environment is used and a
2280  warning is printed.
2281
2282o If neither SROM nor the environment contain a MAC address, an error
2283  is raised.
2284
2285
2286Image Formats:
2287==============
2288
2289The "boot" commands of this monitor operate on "image" files which
2290can be basicly anything, preceeded by a special header; see the
2291definitions in include/image.h for details; basicly, the header
2292defines the following image properties:
2293
2294* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2295  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2296  LynxOS, pSOS, QNX, RTEMS, ARTOS;
2297  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2298* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2299  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2300  Currently supported: ARM, Intel x86, MIPS, NIOS, PowerPC).
2301* Compression Type (uncompressed, gzip, bzip2)
2302* Load Address
2303* Entry Point
2304* Image Name
2305* Image Timestamp
2306
2307The header is marked by a special Magic Number, and both the header
2308and the data portions of the image are secured against corruption by
2309CRC32 checksums.
2310
2311
2312Linux Support:
2313==============
2314
2315Although U-Boot should support any OS or standalone application
2316easily, the main focus has always been on Linux during the design of
2317U-Boot.
2318
2319U-Boot includes many features that so far have been part of some
2320special "boot loader" code within the Linux kernel. Also, any
2321"initrd" images to be used are no longer part of one big Linux image;
2322instead, kernel and "initrd" are separate images. This implementation
2323serves several purposes:
2324
2325- the same features can be used for other OS or standalone
2326  applications (for instance: using compressed images to reduce the
2327  Flash memory footprint)
2328
2329- it becomes much easier to port new Linux kernel versions because
2330  lots of low-level, hardware dependent stuff are done by U-Boot
2331
2332- the same Linux kernel image can now be used with different "initrd"
2333  images; of course this also means that different kernel images can
2334  be run with the same "initrd". This makes testing easier (you don't
2335  have to build a new "zImage.initrd" Linux image when you just
2336  change a file in your "initrd"). Also, a field-upgrade of the
2337  software is easier now.
2338
2339
2340Linux HOWTO:
2341============
2342
2343Porting Linux to U-Boot based systems:
2344---------------------------------------
2345
2346U-Boot cannot save you from doing all the necessary modifications to
2347configure the Linux device drivers for use with your target hardware
2348(no, we don't intend to provide a full virtual machine interface to
2349Linux :-).
2350
2351But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2352
2353Just make sure your machine specific header file (for instance
2354include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2355Information structure as we define in include/u-boot.h, and make
2356sure that your definition of IMAP_ADDR uses the same value as your
2357U-Boot configuration in CFG_IMMR.
2358
2359
2360Configuring the Linux kernel:
2361-----------------------------
2362
2363No specific requirements for U-Boot. Make sure you have some root
2364device (initial ramdisk, NFS) for your target system.
2365
2366
2367Building a Linux Image:
2368-----------------------
2369
2370With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2371not used. If you use recent kernel source, a new build target
2372"uImage" will exist which automatically builds an image usable by
2373U-Boot. Most older kernels also have support for a "pImage" target,
2374which was introduced for our predecessor project PPCBoot and uses a
2375100% compatible format.
2376
2377Example:
2378
2379	make TQM850L_config
2380	make oldconfig
2381	make dep
2382	make uImage
2383
2384The "uImage" build target uses a special tool (in 'tools/mkimage') to
2385encapsulate a compressed Linux kernel image with header	 information,
2386CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2387
2388* build a standard "vmlinux" kernel image (in ELF binary format):
2389
2390* convert the kernel into a raw binary image:
2391
2392	${CROSS_COMPILE}-objcopy -O binary \
2393				 -R .note -R .comment \
2394				 -S vmlinux linux.bin
2395
2396* compress the binary image:
2397
2398	gzip -9 linux.bin
2399
2400* package compressed binary image for U-Boot:
2401
2402	mkimage -A ppc -O linux -T kernel -C gzip \
2403		-a 0 -e 0 -n "Linux Kernel Image" \
2404		-d linux.bin.gz uImage
2405
2406
2407The "mkimage" tool can also be used to create ramdisk images for use
2408with U-Boot, either separated from the Linux kernel image, or
2409combined into one file. "mkimage" encapsulates the images with a 64
2410byte header containing information about target architecture,
2411operating system, image type, compression method, entry points, time
2412stamp, CRC32 checksums, etc.
2413
2414"mkimage" can be called in two ways: to verify existing images and
2415print the header information, or to build new images.
2416
2417In the first form (with "-l" option) mkimage lists the information
2418contained in the header of an existing U-Boot image; this includes
2419checksum verification:
2420
2421	tools/mkimage -l image
2422	  -l ==> list image header information
2423
2424The second form (with "-d" option) is used to build a U-Boot image
2425from a "data file" which is used as image payload:
2426
2427	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2428		      -n name -d data_file image
2429	  -A ==> set architecture to 'arch'
2430	  -O ==> set operating system to 'os'
2431	  -T ==> set image type to 'type'
2432	  -C ==> set compression type 'comp'
2433	  -a ==> set load address to 'addr' (hex)
2434	  -e ==> set entry point to 'ep' (hex)
2435	  -n ==> set image name to 'name'
2436	  -d ==> use image data from 'datafile'
2437
2438Right now, all Linux kernels use the same load address	(0x00000000),
2439but the entry point address depends on the kernel version:
2440
2441- 2.2.x kernels have the entry point at 0x0000000C,
2442- 2.3.x and later kernels have the entry point at 0x00000000.
2443
2444So a typical call to build a U-Boot image would read:
2445
2446	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2447	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2448	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2449	> examples/uImage.TQM850L
2450	Image Name:   2.4.4 kernel for TQM850L
2451	Created:      Wed Jul 19 02:34:59 2000
2452	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2453	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2454	Load Address: 0x00000000
2455	Entry Point:  0x00000000
2456
2457To verify the contents of the image (or check for corruption):
2458
2459	-> tools/mkimage -l examples/uImage.TQM850L
2460	Image Name:   2.4.4 kernel for TQM850L
2461	Created:      Wed Jul 19 02:34:59 2000
2462	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
2463	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
2464	Load Address: 0x00000000
2465	Entry Point:  0x00000000
2466
2467NOTE: for embedded systems where boot time is critical you can trade
2468speed for memory and install an UNCOMPRESSED image instead: this
2469needs more space in Flash, but boots much faster since it does not
2470need to be uncompressed:
2471
2472	-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2473	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2474	> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2475	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2476	> examples/uImage.TQM850L-uncompressed
2477	Image Name:   2.4.4 kernel for TQM850L
2478	Created:      Wed Jul 19 02:34:59 2000
2479	Image Type:   PowerPC Linux Kernel Image (uncompressed)
2480	Data Size:    792160 Bytes = 773.59 kB = 0.76 MB
2481	Load Address: 0x00000000
2482	Entry Point:  0x00000000
2483
2484
2485Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2486when your kernel is intended to use an initial ramdisk:
2487
2488	-> tools/mkimage -n 'Simple Ramdisk Image' \
2489	> -A ppc -O linux -T ramdisk -C gzip \
2490	> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2491	Image Name:   Simple Ramdisk Image
2492	Created:      Wed Jan 12 14:01:50 2000
2493	Image Type:   PowerPC Linux RAMDisk Image (gzip compressed)
2494	Data Size:    566530 Bytes = 553.25 kB = 0.54 MB
2495	Load Address: 0x00000000
2496	Entry Point:  0x00000000
2497
2498
2499Installing a Linux Image:
2500-------------------------
2501
2502To downloading a U-Boot image over the serial (console) interface,
2503you must convert the image to S-Record format:
2504
2505	objcopy -I binary -O srec examples/image examples/image.srec
2506
2507The 'objcopy' does not understand the information in the U-Boot
2508image header, so the resulting S-Record file will be relative to
2509address 0x00000000. To load it to a given address, you need to
2510specify the target address as 'offset' parameter with the 'loads'
2511command.
2512
2513Example: install the image to address 0x40100000 (which on the
2514TQM8xxL is in the first Flash bank):
2515
2516	=> erase 40100000 401FFFFF
2517
2518	.......... done
2519	Erased 8 sectors
2520
2521	=> loads 40100000
2522	## Ready for S-Record download ...
2523	~>examples/image.srec
2524	1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2525	...
2526	15989 15990 15991 15992
2527	[file transfer complete]
2528	[connected]
2529	## Start Addr = 0x00000000
2530
2531
2532You can check the success of the download using the 'iminfo' command;
2533this includes a checksum verification so you  can  be  sure  no	 data
2534corruption happened:
2535
2536	=> imi 40100000
2537
2538	## Checking Image at 40100000 ...
2539	   Image Name:	 2.2.13 for initrd on TQM850L
2540	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2541	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2542	   Load Address: 00000000
2543	   Entry Point:	 0000000c
2544	   Verifying Checksum ... OK
2545
2546
2547Boot Linux:
2548-----------
2549
2550The "bootm" command is used to boot an application that is stored in
2551memory (RAM or Flash). In case of a Linux kernel image, the contents
2552of the "bootargs" environment variable is passed to the kernel as
2553parameters. You can check and modify this variable using the
2554"printenv" and "setenv" commands:
2555
2556
2557	=> printenv bootargs
2558	bootargs=root=/dev/ram
2559
2560	=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2561
2562	=> printenv bootargs
2563	bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2564
2565	=> bootm 40020000
2566	## Booting Linux kernel at 40020000 ...
2567	   Image Name:	 2.2.13 for NFS on TQM850L
2568	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2569	   Data Size:	 381681 Bytes = 372 kB = 0 MB
2570	   Load Address: 00000000
2571	   Entry Point:	 0000000c
2572	   Verifying Checksum ... OK
2573	   Uncompressing Kernel Image ... OK
2574	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
2575	Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2576	time_init: decrementer frequency = 187500000/60
2577	Calibrating delay loop... 49.77 BogoMIPS
2578	Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2579	...
2580
2581If you want to boot a Linux kernel with initial ram disk, you pass
2582the memory addresses of both the kernel and the initrd image (PPBCOOT
2583format!) to the "bootm" command:
2584
2585	=> imi 40100000 40200000
2586
2587	## Checking Image at 40100000 ...
2588	   Image Name:	 2.2.13 for initrd on TQM850L
2589	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2590	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2591	   Load Address: 00000000
2592	   Entry Point:	 0000000c
2593	   Verifying Checksum ... OK
2594
2595	## Checking Image at 40200000 ...
2596	   Image Name:	 Simple Ramdisk Image
2597	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2598	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2599	   Load Address: 00000000
2600	   Entry Point:	 00000000
2601	   Verifying Checksum ... OK
2602
2603	=> bootm 40100000 40200000
2604	## Booting Linux kernel at 40100000 ...
2605	   Image Name:	 2.2.13 for initrd on TQM850L
2606	   Image Type:	 PowerPC Linux Kernel Image (gzip compressed)
2607	   Data Size:	 335725 Bytes = 327 kB = 0 MB
2608	   Load Address: 00000000
2609	   Entry Point:	 0000000c
2610	   Verifying Checksum ... OK
2611	   Uncompressing Kernel Image ... OK
2612	## Loading RAMDisk Image at 40200000 ...
2613	   Image Name:	 Simple Ramdisk Image
2614	   Image Type:	 PowerPC Linux RAMDisk Image (gzip compressed)
2615	   Data Size:	 566530 Bytes = 553 kB = 0 MB
2616	   Load Address: 00000000
2617	   Entry Point:	 00000000
2618	   Verifying Checksum ... OK
2619	   Loading Ramdisk ... OK
2620	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
2621	Boot arguments: root=/dev/ram
2622	time_init: decrementer frequency = 187500000/60
2623	Calibrating delay loop... 49.77 BogoMIPS
2624	...
2625	RAMDISK: Compressed image found at block 0
2626	VFS: Mounted root (ext2 filesystem).
2627
2628	bash#
2629
2630More About U-Boot Image Types:
2631------------------------------
2632
2633U-Boot supports the following image types:
2634
2635   "Standalone Programs" are directly runnable in the environment
2636	provided by U-Boot; it is expected that (if they behave
2637	well) you can continue to work in U-Boot after return from
2638	the Standalone Program.
2639   "OS Kernel Images" are usually images of some Embedded OS which
2640	will take over control completely. Usually these programs
2641	will install their own set of exception handlers, device
2642	drivers, set up the MMU, etc. - this means, that you cannot
2643	expect to re-enter U-Boot except by resetting the CPU.
2644   "RAMDisk Images" are more or less just data blocks, and their
2645	parameters (address, size) are passed to an OS kernel that is
2646	being started.
2647   "Multi-File Images" contain several images, typically an OS
2648	(Linux) kernel image and one or more data images like
2649	RAMDisks. This construct is useful for instance when you want
2650	to boot over the network using BOOTP etc., where the boot
2651	server provides just a single image file, but you want to get
2652	for instance an OS kernel and a RAMDisk image.
2653
2654	"Multi-File Images" start with a list of image sizes, each
2655	image size (in bytes) specified by an "uint32_t" in network
2656	byte order. This list is terminated by an "(uint32_t)0".
2657	Immediately after the terminating 0 follow the images, one by
2658	one, all aligned on "uint32_t" boundaries (size rounded up to
2659	a multiple of 4 bytes).
2660
2661   "Firmware Images" are binary images containing firmware (like
2662	U-Boot or FPGA images) which usually will be programmed to
2663	flash memory.
2664
2665   "Script files" are command sequences that will be executed by
2666	U-Boot's command interpreter; this feature is especially
2667	useful when you configure U-Boot to use a real shell (hush)
2668	as command interpreter.
2669
2670
2671Standalone HOWTO:
2672=================
2673
2674One of the features of U-Boot is that you can dynamically load and
2675run "standalone" applications, which can use some resources of
2676U-Boot like console I/O functions or interrupt services.
2677
2678Two simple examples are included with the sources:
2679
2680"Hello World" Demo:
2681-------------------
2682
2683'examples/hello_world.c' contains a small "Hello World" Demo
2684application; it is automatically compiled when you build U-Boot.
2685It's configured to run at address 0x00040004, so you can play with it
2686like that:
2687
2688	=> loads
2689	## Ready for S-Record download ...
2690	~>examples/hello_world.srec
2691	1 2 3 4 5 6 7 8 9 10 11 ...
2692	[file transfer complete]
2693	[connected]
2694	## Start Addr = 0x00040004
2695
2696	=> go 40004 Hello World! This is a test.
2697	## Starting application at 0x00040004 ...
2698	Hello World
2699	argc = 7
2700	argv[0] = "40004"
2701	argv[1] = "Hello"
2702	argv[2] = "World!"
2703	argv[3] = "This"
2704	argv[4] = "is"
2705	argv[5] = "a"
2706	argv[6] = "test."
2707	argv[7] = "<NULL>"
2708	Hit any key to exit ...
2709
2710	## Application terminated, rc = 0x0
2711
2712Another example, which demonstrates how to register a CPM interrupt
2713handler with the U-Boot code, can be found in 'examples/timer.c'.
2714Here, a CPM timer is set up to generate an interrupt every second.
2715The interrupt service routine is trivial, just printing a '.'
2716character, but this is just a demo program. The application can be
2717controlled by the following keys:
2718
2719	? - print current values og the CPM Timer registers
2720	b - enable interrupts and start timer
2721	e - stop timer and disable interrupts
2722	q - quit application
2723
2724	=> loads
2725	## Ready for S-Record download ...
2726	~>examples/timer.srec
2727	1 2 3 4 5 6 7 8 9 10 11 ...
2728	[file transfer complete]
2729	[connected]
2730	## Start Addr = 0x00040004
2731
2732	=> go 40004
2733	## Starting application at 0x00040004 ...
2734	TIMERS=0xfff00980
2735	Using timer 1
2736	  tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2737
2738Hit 'b':
2739	[q, b, e, ?] Set interval 1000000 us
2740	Enabling timer
2741Hit '?':
2742	[q, b, e, ?] ........
2743	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2744Hit '?':
2745	[q, b, e, ?] .
2746	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2747Hit '?':
2748	[q, b, e, ?] .
2749	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2750Hit '?':
2751	[q, b, e, ?] .
2752	tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2753Hit 'e':
2754	[q, b, e, ?] ...Stopping timer
2755Hit 'q':
2756	[q, b, e, ?] ## Application terminated, rc = 0x0
2757
2758
2759Minicom warning:
2760================
2761
2762Over time, many people have reported problems when trying to use the
2763"minicom" terminal emulation program for serial download. I (wd)
2764consider minicom to be broken, and recommend not to use it. Under
2765Unix, I recommend to use C-Kermit for general purpose use (and
2766especially for kermit binary protocol download ("loadb" command), and
2767use "cu" for S-Record download ("loads" command).
2768
2769Nevertheless, if you absolutely want to use it try adding this
2770configuration to your "File transfer protocols" section:
2771
2772	   Name	   Program			Name U/D FullScr IO-Red. Multi
2773	X  kermit  /usr/bin/kermit -i -l %l -s	 Y    U	   Y	   N	  N
2774	Y  kermit  /usr/bin/kermit -i -l %l -r	 N    D	   Y	   N	  N
2775
2776
2777NetBSD Notes:
2778=============
2779
2780Starting at version 0.9.2, U-Boot supports NetBSD both as host
2781(build U-Boot) and target system (boots NetBSD/mpc8xx).
2782
2783Building requires a cross environment; it is known to work on
2784NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2785need gmake since the Makefiles are not compatible with BSD make).
2786Note that the cross-powerpc package does not install include files;
2787attempting to build U-Boot will fail because <machine/ansi.h> is
2788missing.  This file has to be installed and patched manually:
2789
2790	# cd /usr/pkg/cross/powerpc-netbsd/include
2791	# mkdir powerpc
2792	# ln -s powerpc machine
2793	# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2794	# ${EDIT} powerpc/ansi.h	## must remove __va_list, _BSD_VA_LIST
2795
2796Native builds *don't* work due to incompatibilities between native
2797and U-Boot include files.
2798
2799Booting assumes that (the first part of) the image booted is a
2800stage-2 loader which in turn loads and then invokes the kernel
2801proper. Loader sources will eventually appear in the NetBSD source
2802tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2803meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2804details.
2805
2806
2807Implementation Internals:
2808=========================
2809
2810The following is not intended to be a complete description of every
2811implementation detail. However, it should help to understand the
2812inner workings of U-Boot and make it easier to port it to custom
2813hardware.
2814
2815
2816Initial Stack, Global Data:
2817---------------------------
2818
2819The implementation of U-Boot is complicated by the fact that U-Boot
2820starts running out of ROM (flash memory), usually without access to
2821system RAM (because the memory controller is not initialized yet).
2822This means that we don't have writable Data or BSS segments, and BSS
2823is not initialized as zero. To be able to get a C environment working
2824at all, we have to allocate at least a minimal stack. Implementation
2825options for this are defined and restricted by the CPU used: Some CPU
2826models provide on-chip memory (like the IMMR area on MPC8xx and
2827MPC826x processors), on others (parts of) the data cache can be
2828locked as (mis-) used as memory, etc.
2829
2830	Chris Hallinan posted a good summary of	 these	issues	to  the
2831	u-boot-users mailing list:
2832
2833	Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2834	From: "Chris Hallinan" <clh@net1plus.com>
2835	Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2836	...
2837
2838	Correct me if I'm wrong, folks, but the way I understand it
2839	is this: Using DCACHE as initial RAM for Stack, etc, does not
2840	require any physical RAM backing up the cache. The cleverness
2841	is that the cache is being used as a temporary supply of
2842	necessary storage before the SDRAM controller is setup. It's
2843	beyond the scope of this list to expain the details, but you
2844	can see how this works by studying the cache architecture and
2845	operation in the architecture and processor-specific manuals.
2846
2847	OCM is On Chip Memory, which I believe the 405GP has 4K. It
2848	is another option for the system designer to use as an
2849	initial stack/ram area prior to SDRAM being available. Either
2850	option should work for you. Using CS 4 should be fine if your
2851	board designers haven't used it for something that would
2852	cause you grief during the initial boot! It is frequently not
2853	used.
2854
2855	CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2856	with your processor/board/system design. The default value
2857	you will find in any recent u-boot distribution in
2858	Walnut405.h should work for you. I'd set it to a value larger
2859	than your SDRAM module. If you have a 64MB SDRAM module, set
2860	it above 400_0000. Just make sure your board has no resources
2861	that are supposed to respond to that address! That code in
2862	start.S has been around a while and should work as is when
2863	you get the config right.
2864
2865	-Chris Hallinan
2866	DS4.COM, Inc.
2867
2868It is essential to remember this, since it has some impact on the C
2869code for the initialization procedures:
2870
2871* Initialized global data (data segment) is read-only. Do not attempt
2872  to write it.
2873
2874* Do not use any unitialized global data (or implicitely initialized
2875  as zero data - BSS segment) at all - this is undefined, initiali-
2876  zation is performed later (when relocating to RAM).
2877
2878* Stack space is very limited. Avoid big data buffers or things like
2879  that.
2880
2881Having only the stack as writable memory limits means we cannot use
2882normal global data to share information beween the code. But it
2883turned out that the implementation of U-Boot can be greatly
2884simplified by making a global data structure (gd_t) available to all
2885functions. We could pass a pointer to this data as argument to _all_
2886functions, but this would bloat the code. Instead we use a feature of
2887the GCC compiler (Global Register Variables) to share the data: we
2888place a pointer (gd) to the global data into a register which we
2889reserve for this purpose.
2890
2891When choosing a register for such a purpose we are restricted by the
2892relevant  (E)ABI  specifications for the current architecture, and by
2893GCC's implementation.
2894
2895For PowerPC, the following registers have specific use:
2896	R1:	stack pointer
2897	R2:	TOC pointer
2898	R3-R4:	parameter passing and return values
2899	R5-R10: parameter passing
2900	R13:	small data area pointer
2901	R30:	GOT pointer
2902	R31:	frame pointer
2903
2904	(U-Boot also uses R14 as internal GOT pointer.)
2905
2906    ==> U-Boot will use R29 to hold a pointer to the global data
2907
2908    Note: on PPC, we could use a static initializer (since the
2909    address of the global data structure is known at compile time),
2910    but it turned out that reserving a register results in somewhat
2911    smaller code - although the code savings are not that big (on
2912    average for all boards 752 bytes for the whole U-Boot image,
2913    624 text + 127 data).
2914
2915On ARM, the following registers are used:
2916
2917	R0:	function argument word/integer result
2918	R1-R3:	function argument word
2919	R9:	GOT pointer
2920	R10:	stack limit (used only if stack checking if enabled)
2921	R11:	argument (frame) pointer
2922	R12:	temporary workspace
2923	R13:	stack pointer
2924	R14:	link register
2925	R15:	program counter
2926
2927    ==> U-Boot will use R8 to hold a pointer to the global data
2928
2929
2930Memory Management:
2931------------------
2932
2933U-Boot runs in system state and uses physical addresses, i.e. the
2934MMU is not used either for address mapping nor for memory protection.
2935
2936The available memory is mapped to fixed addresses using the memory
2937controller. In this process, a contiguous block is formed for each
2938memory type (Flash, SDRAM, SRAM), even when it consists of several
2939physical memory banks.
2940
2941U-Boot is installed in the first 128 kB of the first Flash bank (on
2942TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2943booting and sizing and initializing DRAM, the code relocates itself
2944to the upper end of DRAM. Immediately below the U-Boot code some
2945memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2946configuration setting]. Below that, a structure with global Board
2947Info data is placed, followed by the stack (growing downward).
2948
2949Additionally, some exception handler code is copied to the low 8 kB
2950of DRAM (0x00000000 ... 0x00001FFF).
2951
2952So a typical memory configuration with 16 MB of DRAM could look like
2953this:
2954
2955	0x0000 0000	Exception Vector code
2956	      :
2957	0x0000 1FFF
2958	0x0000 2000	Free for Application Use
2959	      :
2960	      :
2961
2962	      :
2963	      :
2964	0x00FB FF20	Monitor Stack (Growing downward)
2965	0x00FB FFAC	Board Info Data and permanent copy of global data
2966	0x00FC 0000	Malloc Arena
2967	      :
2968	0x00FD FFFF
2969	0x00FE 0000	RAM Copy of Monitor Code
2970	...		eventually: LCD or video framebuffer
2971	...		eventually: pRAM (Protected RAM - unchanged by reset)
2972	0x00FF FFFF	[End of RAM]
2973
2974
2975System Initialization:
2976----------------------
2977
2978In the reset configuration, U-Boot starts at the reset entry point
2979(on most PowerPC systens at address 0x00000100). Because of the reset
2980configuration for CS0# this is a mirror of the onboard Flash memory.
2981To be able to re-map memory U-Boot then jumps to its link address.
2982To be able to implement the initialization code in C, a (small!)
2983initial stack is set up in the internal Dual Ported RAM (in case CPUs
2984which provide such a feature like MPC8xx or MPC8260), or in a locked
2985part of the data cache. After that, U-Boot initializes the CPU core,
2986the caches and the SIU.
2987
2988Next, all (potentially) available memory banks are mapped using a
2989preliminary mapping. For example, we put them on 512 MB boundaries
2990(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2991on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2992programmed for SDRAM access. Using the temporary configuration, a
2993simple memory test is run that determines the size of the SDRAM
2994banks.
2995
2996When there is more than one SDRAM bank, and the banks are of
2997different size, the largest is mapped first. For equal size, the first
2998bank (CS2#) is mapped first. The first mapping is always for address
29990x00000000, with any additional banks following immediately to create
3000contiguous memory starting from 0.
3001
3002Then, the monitor installs itself at the upper end of the SDRAM area
3003and allocates memory for use by malloc() and for the global Board
3004Info data; also, the exception vector code is copied to the low RAM
3005pages, and the final stack is set up.
3006
3007Only after this relocation will you have a "normal" C environment;
3008until that you are restricted in several ways, mostly because you are
3009running from ROM, and because the code will have to be relocated to a
3010new address in RAM.
3011
3012
3013U-Boot Porting Guide:
3014----------------------
3015
3016[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3017list, October 2002]
3018
3019
3020int main (int argc, char *argv[])
3021{
3022	sighandler_t no_more_time;
3023
3024	signal (SIGALRM, no_more_time);
3025	alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3026
3027	if (available_money > available_manpower) {
3028		pay consultant to port U-Boot;
3029		return 0;
3030	}
3031
3032	Download latest U-Boot source;
3033
3034	Subscribe to u-boot-users mailing list;
3035
3036	if (clueless) {
3037		email ("Hi, I am new to U-Boot, how do I get started?");
3038	}
3039
3040	while (learning) {
3041		Read the README file in the top level directory;
3042		Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3043		Read the source, Luke;
3044	}
3045
3046	if (available_money > toLocalCurrency ($2500)) {
3047		Buy a BDI2000;
3048	} else {
3049		Add a lot of aggravation and time;
3050	}
3051
3052	Create your own board support subdirectory;
3053
3054	Create your own board config file;
3055
3056	while (!running) {
3057		do {
3058			Add / modify source code;
3059		} until (compiles);
3060		Debug;
3061		if (clueless)
3062			email ("Hi, I am having problems...");
3063	}
3064	Send patch file to Wolfgang;
3065
3066	return 0;
3067}
3068
3069void no_more_time (int sig)
3070{
3071      hire_a_guru();
3072}
3073
3074
3075Coding Standards:
3076-----------------
3077
3078All contributions to U-Boot should conform to the Linux kernel
3079coding style; see the file "Documentation/CodingStyle" in your Linux
3080kernel source directory.
3081
3082Please note that U-Boot is implemented in C (and to some small parts
3083in Assembler); no C++ is used, so please do not use C++ style
3084comments (//) in your code.
3085
3086Please also stick to the following formatting rules:
3087- remove any trailing white space
3088- use TAB characters for indentation, not spaces
3089- make sure NOT to use DOS '\r\n' line feeds
3090- do not add more than 2 empty lines to source files
3091- do not add trailing empty lines to source files
3092
3093Submissions which do not conform to the standards may be returned
3094with a request to reformat the changes.
3095
3096
3097Submitting Patches:
3098-------------------
3099
3100Since the number of patches for U-Boot is growing, we need to
3101establish some rules. Submissions which do not conform to these rules
3102may be rejected, even when they contain important and valuable stuff.
3103
3104
3105When you send a patch, please include the following information with
3106it:
3107
3108* For bug fixes: a description of the bug and how your patch fixes
3109  this bug. Please try to include a way of demonstrating that the
3110  patch actually fixes something.
3111
3112* For new features: a description of the feature and your
3113  implementation.
3114
3115* A CHANGELOG entry as plaintext (separate from the patch)
3116
3117* For major contributions, your entry to the CREDITS file
3118
3119* When you add support for a new board, don't forget to add this
3120  board to the MAKEALL script, too.
3121
3122* If your patch adds new configuration options, don't forget to
3123  document these in the README file.
3124
3125* The patch itself. If you are accessing the CVS repository use "cvs
3126  update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3127  version of diff does not support these options, then get the latest
3128  version of GNU diff.
3129
3130  The current directory when running this command shall be the top
3131  level directory of the U-Boot source tree, or it's parent directory
3132  (i. e. please make sure that your patch includes sufficient
3133  directory information for the affected files).
3134
3135  We accept patches as plain text, MIME attachments or as uuencoded
3136  gzipped text.
3137
3138* If one logical set of modifications affects or creates several
3139  files, all these changes shall be submitted in a SINGLE patch file.
3140
3141* Changesets that contain different, unrelated modifications shall be
3142  submitted as SEPARATE patches, one patch per changeset.
3143
3144
3145Notes:
3146
3147* Before sending the patch, run the MAKEALL script on your patched
3148  source tree and make sure that no errors or warnings are reported
3149  for any of the boards.
3150
3151* Keep your modifications to the necessary minimum: A patch
3152  containing several unrelated changes or arbitrary reformats will be
3153  returned with a request to re-formatting / split it.
3154
3155* If you modify existing code, make sure that your new code does not
3156  add to the memory footprint of the code ;-) Small is beautiful!
3157  When adding new features, these should compile conditionally only
3158  (using #ifdef), and the resulting code with the new feature
3159  disabled must not need more memory than the old code without your
3160  modification.
3161