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wdenkc6097192002-11-03 00:24:07 +00001#
2# (C) Copyright 2000 - 2002
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
wdenk24ee89b2002-11-03 17:56:27 +000027This 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.
wdenkc6097192002-11-03 00:24:07 +000031
32The development of U-Boot is closely related to Linux: some parts of
wdenk24ee89b2002-11-03 17:56:27 +000033the source code originate in the Linux source tree, we have some
34header files in common, and special provision has been made to
wdenkc6097192002-11-03 00:24:07 +000035support 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
wdenk24ee89b2002-11-03 17:56:27 +000049Makefile have been tested to some extent and can be considered
wdenkc6097192002-11-03 00:24:07 +000050"working". In fact, many of them are used in production systems.
51
wdenk24ee89b2002-11-03 17:56:27 +000052In case of problems see the CHANGELOG and CREDITS files to find out
wdenkc6097192002-11-03 00:24:07 +000053who contributed the specific port.
54
wdenkc6097192002-11-03 00:24:07 +000055
56Where to get help:
57==================
58
wdenk24ee89b2002-11-03 17:56:27 +000059In 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
wdenkc6097192002-11-03 00:24:07 +000063before 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
wdenk24ee89b2002-11-03 17:56:27 +000071- create PPCBoot project (http://sourceforge.net/projects/ppcboot)
wdenkc6097192002-11-03 00:24:07 +000072- 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
wdenk24ee89b2002-11-03 17:56:27 +000080- create ARMBoot project (http://sourceforge.net/projects/armboot)
wdenkc6097192002-11-03 00:24:07 +000081- add other CPU families (starting with ARM)
wdenk24ee89b2002-11-03 17:56:27 +000082- 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
wdenkc6097192002-11-03 00:24:07 +0000105
106
wdenk93f19cc2002-12-17 17:55:09 +0000107Versioning:
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
wdenkc6097192002-11-03 00:24:07 +0000119Directory Hierarchy:
120====================
121
122- board Board dependend files
123- common Misc architecture independend functions
124- cpu CPU specific files
125- disk Code for disk drive partition handling
126- doc Documentation (don't expect too much)
127- drivers Common used device drivers
128- dtt Digital Thermometer and Thermostat drivers
129- examples Example code for standalone applications, etc.
130- include Header Files
131- disk Harddisk interface code
132- net Networking code
133- ppc Files generic to PowerPC architecture
134- post Power On Self Test
135- post/arch Symlink to architecture specific Power On Self Test
136- post/arch-ppc PowerPC architecture specific Power On Self Test
137- post/cpu/mpc8260 MPC8260 CPU specific Power On Self Test
138- post/cpu/mpc8xx MPC8xx CPU specific Power On Self Test
139- rtc Real Time Clock drivers
140- tools Tools to build S-Record or U-Boot images, etc.
141
142- cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
wdenk0db5bca2003-03-31 17:27:09 +0000143- cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
wdenkc6097192002-11-03 00:24:07 +0000144- cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
145- cpu/mpc824x Files specific to Motorola MPC824x CPUs
146- cpu/mpc8260 Files specific to Motorola MPC8260 CPU
147- cpu/ppc4xx Files specific to IBM 4xx CPUs
148
wdenk3bac3512003-03-12 10:41:04 +0000149- board/LEOX/ Files specific to boards manufactured by The LEOX team
150- board/LEOX/elpt860 Files specific to ELPT860 boards
wdenkc6097192002-11-03 00:24:07 +0000151- board/RPXClassic
152 Files specific to RPXClassic boards
153- board/RPXlite Files specific to RPXlite boards
154- board/c2mon Files specific to c2mon boards
wdenk0db5bca2003-03-31 17:27:09 +0000155- board/cmi Files specific to cmi boards
wdenkc6097192002-11-03 00:24:07 +0000156- board/cogent Files specific to Cogent boards
157 (need further configuration)
158 Files specific to CPCIISER4 boards
159- board/cpu86 Files specific to CPU86 boards
160- board/cray/ Files specific to boards manufactured by Cray
161- board/cray/L1 Files specific to L1 boards
162- board/cu824 Files specific to CU824 boards
163- board/ebony Files specific to IBM Ebony board
164- board/eric Files specific to ERIC boards
165- board/esd/ Files specific to boards manufactured by ESD
166- board/esd/adciop Files specific to ADCIOP boards
167- board/esd/ar405 Files specific to AR405 boards
168- board/esd/canbt Files specific to CANBT boards
169- board/esd/cpci405 Files specific to CPCI405 boards
170- board/esd/cpciiser4 Files specific to CPCIISER4 boards
171- board/esd/common Common files for ESD boards
172- board/esd/dasa_sim Files specific to DASA_SIM boards
173- board/esd/du405 Files specific to DU405 boards
174- board/esd/ocrtc Files specific to OCRTC boards
175- board/esd/pci405 Files specific to PCI405 boards
176- board/esteem192e
177 Files specific to ESTEEM192E boards
178- board/etx094 Files specific to ETX_094 boards
179- board/evb64260
180 Files specific to EVB64260 boards
181- board/fads Files specific to FADS boards
182- board/flagadm Files specific to FLAGADM boards
183- board/gen860t Files specific to GEN860T boards
184- board/genietv Files specific to GENIETV boards
185- board/gth Files specific to GTH boards
186- board/hermes Files specific to HERMES boards
187- board/hymod Files specific to HYMOD boards
188- board/icu862 Files specific to ICU862 boards
189- board/ip860 Files specific to IP860 boards
190- board/iphase4539
191 Files specific to Interphase4539 boards
192- board/ivm Files specific to IVMS8/IVML24 boards
193- board/lantec Files specific to LANTEC boards
194- board/lwmon Files specific to LWMON boards
195- board/mbx8xx Files specific to MBX boards
196- board/mpc8260ads
197 Files specific to MMPC8260ADS boards
198- board/mpl/ Files specific to boards manufactured by MPL
199- board/mpl/common Common files for MPL boards
200- board/mpl/pip405 Files specific to PIP405 boards
201- board/mpl/mip405 Files specific to MIP405 boards
202- board/musenki Files specific to MUSEKNI boards
203- board/mvs1 Files specific to MVS1 boards
204- board/nx823 Files specific to NX823 boards
205- board/oxc Files specific to OXC boards
206- board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
207- board/pm826 Files specific to PM826 boards
208- board/ppmc8260
209 Files specific to PPMC8260 boards
210- board/rpxsuper
211 Files specific to RPXsuper boards
212- board/rsdproto
213 Files specific to RSDproto boards
214- board/sandpoint
215 Files specific to Sandpoint boards
216- board/sbc8260 Files specific to SBC8260 boards
217- board/sacsng Files specific to SACSng boards
218- board/siemens Files specific to boards manufactured by Siemens AG
219- board/siemens/CCM Files specific to CCM boards
220- board/siemens/IAD210 Files specific to IAD210 boards
221- board/siemens/SCM Files specific to SCM boards
222- board/siemens/pcu_e Files specific to PCU_E boards
223- board/sixnet Files specific to SIXNET boards
224- board/spd8xx Files specific to SPD8xxTS boards
225- board/tqm8260 Files specific to TQM8260 boards
226- board/tqm8xx Files specific to TQM8xxL boards
227- board/w7o Files specific to W7O boards
228- board/walnut405
229 Files specific to Walnut405 boards
230- board/westel/ Files specific to boards manufactured by Westel Wireless
231- board/westel/amx860 Files specific to AMX860 boards
232- board/utx8245 Files specific to UTX8245 boards
233
234Software Configuration:
235=======================
236
237Configuration is usually done using C preprocessor defines; the
238rationale behind that is to avoid dead code whenever possible.
239
240There are two classes of configuration variables:
241
242* Configuration _OPTIONS_:
243 These are selectable by the user and have names beginning with
244 "CONFIG_".
245
246* Configuration _SETTINGS_:
247 These depend on the hardware etc. and should not be meddled with if
248 you don't know what you're doing; they have names beginning with
249 "CFG_".
250
251Later we will add a configuration tool - probably similar to or even
252identical to what's used for the Linux kernel. Right now, we have to
253do the configuration by hand, which means creating some symbolic
254links and editing some configuration files. We use the TQM8xxL boards
255as an example here.
256
257
258Selection of Processor Architecture and Board Type:
259---------------------------------------------------
260
261For all supported boards there are ready-to-use default
262configurations available; just type "make <board_name>_config".
263
264Example: For a TQM823L module type:
265
266 cd u-boot
267 make TQM823L_config
268
269For the Cogent platform, you need to specify the cpu type as well;
270e.g. "make cogent_mpc8xx_config". And also configure the cogent
271directory according to the instructions in cogent/README.
272
273
274Configuration Options:
275----------------------
276
277Configuration depends on the combination of board and CPU type; all
278such information is kept in a configuration file
279"include/configs/<board_name>.h".
280
281Example: For a TQM823L module, all configuration settings are in
282"include/configs/TQM823L.h".
283
284
wdenk7f6c2cb2002-11-10 22:06:23 +0000285Many of the options are named exactly as the corresponding Linux
286kernel configuration options. The intention is to make it easier to
287build a config tool - later.
288
289
wdenkc6097192002-11-03 00:24:07 +0000290The following options need to be configured:
291
292- CPU Type: Define exactly one of
293
294 PowerPC based CPUs:
295 -------------------
296 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
wdenk0db5bca2003-03-31 17:27:09 +0000297 or CONFIG_MPC5xx
wdenkc6097192002-11-03 00:24:07 +0000298 or CONFIG_MPC824X, CONFIG_MPC8260
299 or CONFIG_IOP480
300 or CONFIG_405GP
301 or CONFIG_440
302 or CONFIG_MPC74xx
303
304 ARM based CPUs:
305 ---------------
306 CONFIG_SA1110
307 CONFIG_ARM7
308 CONFIG_PXA250
309
310
311- Board Type: Define exactly one of
312
313 PowerPC based boards:
314 ---------------------
315
316 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
317 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
318 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
319 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
320 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
321 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
322 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
323 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
324 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
325 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
326 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
327 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
328 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
329 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
330 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
331 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
332 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
333 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
334 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
335 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
336 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
337 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
338 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
339 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
340 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
341 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
342 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
343 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
344 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
wdenk608c9142003-01-13 23:54:46 +0000345 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
wdenk0db5bca2003-03-31 17:27:09 +0000346 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI
wdenkc6097192002-11-03 00:24:07 +0000347
348 ARM based boards:
349 -----------------
350
351 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
352 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
353 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
354 CONFIG_TRAB
355
356
357- CPU Module Type: (if CONFIG_COGENT is defined)
358 Define exactly one of
359 CONFIG_CMA286_60_OLD
360--- FIXME --- not tested yet:
361 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
362 CONFIG_CMA287_23, CONFIG_CMA287_50
363
364- Motherboard Type: (if CONFIG_COGENT is defined)
365 Define exactly one of
366 CONFIG_CMA101, CONFIG_CMA102
367
368- Motherboard I/O Modules: (if CONFIG_COGENT is defined)
369 Define one or more of
370 CONFIG_CMA302
371
372- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
373 Define one or more of
374 CONFIG_LCD_HEARTBEAT - update a character position on
375 the lcd display every second with
376 a "rotator" |\-/|\-/
377
378- MPC824X Family Member (if CONFIG_MPC824X is defined)
379 Define exactly one of
380 CONFIG_MPC8240, CONFIG_MPC8245
381
382- 8xx CPU Options: (if using an 8xx cpu)
383 Define one or more of
384 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
385 no 32KHz reference PIT/RTC clock
386
387- Clock Interface:
388 CONFIG_CLOCKS_IN_MHZ
389
390 U-Boot stores all clock information in Hz
391 internally. For binary compatibility with older Linux
392 kernels (which expect the clocks passed in the
393 bd_info data to be in MHz) the environment variable
394 "clocks_in_mhz" can be defined so that U-Boot
395 converts clock data to MHZ before passing it to the
396 Linux kernel.
397
398 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
399 "clocks_in_mhz=1" is automatically included in the
400 default environment.
401
402- Console Interface:
wdenk43d96162003-03-06 00:02:04 +0000403 Depending on board, define exactly one serial port
404 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
405 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
406 console by defining CONFIG_8xx_CONS_NONE
wdenkc6097192002-11-03 00:24:07 +0000407
408 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
409 port routines must be defined elsewhere
410 (i.e. serial_init(), serial_getc(), ...)
411
412 CONFIG_CFB_CONSOLE
413 Enables console device for a color framebuffer. Needs following
414 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
415 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
416 (default big endian)
417 VIDEO_HW_RECTFILL graphic chip supports
418 rectangle fill
419 (cf. smiLynxEM)
420 VIDEO_HW_BITBLT graphic chip supports
421 bit-blit (cf. smiLynxEM)
422 VIDEO_VISIBLE_COLS visible pixel columns
423 (cols=pitch)
424 VIDEO_VISIBLE_ROWS visible pixel rows
425 VIDEO_PIXEL_SIZE bytes per pixel
426 VIDEO_DATA_FORMAT graphic data format
427 (0-5, cf. cfb_console.c)
428 VIDEO_FB_ADRS framebuffer address
429 VIDEO_KBD_INIT_FCT keyboard int fct
430 (i.e. i8042_kbd_init())
431 VIDEO_TSTC_FCT test char fct
432 (i.e. i8042_tstc)
433 VIDEO_GETC_FCT get char fct
434 (i.e. i8042_getc)
435 CONFIG_CONSOLE_CURSOR cursor drawing on/off
436 (requires blink timer
437 cf. i8042.c)
438 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
439 CONFIG_CONSOLE_TIME display time/date info in
440 upper right corner
441 (requires CFG_CMD_DATE)
442 CONFIG_VIDEO_LOGO display Linux logo in
443 upper left corner
wdenka6c7ad22002-12-03 21:28:10 +0000444 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
445 linux_logo.h for logo.
446 Requires CONFIG_VIDEO_LOGO
wdenkc6097192002-11-03 00:24:07 +0000447 CONFIG_CONSOLE_EXTRA_INFO
448 addional board info beside
449 the logo
450
wdenk43d96162003-03-06 00:02:04 +0000451 When CONFIG_CFB_CONSOLE is defined, video console is
452 default i/o. Serial console can be forced with
453 environment 'console=serial'.
wdenkc6097192002-11-03 00:24:07 +0000454
455- Console Baudrate:
456 CONFIG_BAUDRATE - in bps
457 Select one of the baudrates listed in
458 CFG_BAUDRATE_TABLE, see below.
459
460- Interrupt driven serial port input:
461 CONFIG_SERIAL_SOFTWARE_FIFO
462
463 PPC405GP only.
464 Use an interrupt handler for receiving data on the
465 serial port. It also enables using hardware handshake
466 (RTS/CTS) and UART's built-in FIFO. Set the number of
467 bytes the interrupt driven input buffer should have.
468
469 Set to 0 to disable this feature (this is the default).
470 This will also disable hardware handshake.
471
472- Boot Delay: CONFIG_BOOTDELAY - in seconds
473 Delay before automatically booting the default image;
474 set to -1 to disable autoboot.
475
476 See doc/README.autoboot for these options that
477 work with CONFIG_BOOTDELAY. None are required.
478 CONFIG_BOOT_RETRY_TIME
479 CONFIG_BOOT_RETRY_MIN
480 CONFIG_AUTOBOOT_KEYED
481 CONFIG_AUTOBOOT_PROMPT
482 CONFIG_AUTOBOOT_DELAY_STR
483 CONFIG_AUTOBOOT_STOP_STR
484 CONFIG_AUTOBOOT_DELAY_STR2
485 CONFIG_AUTOBOOT_STOP_STR2
486 CONFIG_ZERO_BOOTDELAY_CHECK
487 CONFIG_RESET_TO_RETRY
488
489- Autoboot Command:
490 CONFIG_BOOTCOMMAND
491 Only needed when CONFIG_BOOTDELAY is enabled;
492 define a command string that is automatically executed
493 when no character is read on the console interface
494 within "Boot Delay" after reset.
495
496 CONFIG_BOOTARGS
wdenk43d96162003-03-06 00:02:04 +0000497 This can be used to pass arguments to the bootm
498 command. The value of CONFIG_BOOTARGS goes into the
499 environment value "bootargs".
wdenkc6097192002-11-03 00:24:07 +0000500
501 CONFIG_RAMBOOT and CONFIG_NFSBOOT
wdenk43d96162003-03-06 00:02:04 +0000502 The value of these goes into the environment as
503 "ramboot" and "nfsboot" respectively, and can be used
504 as a convenience, when switching between booting from
505 ram and nfs.
wdenkc6097192002-11-03 00:24:07 +0000506
507- Pre-Boot Commands:
508 CONFIG_PREBOOT
509
510 When this option is #defined, the existence of the
511 environment variable "preboot" will be checked
512 immediately before starting the CONFIG_BOOTDELAY
513 countdown and/or running the auto-boot command resp.
514 entering interactive mode.
515
516 This feature is especially useful when "preboot" is
517 automatically generated or modified. For an example
518 see the LWMON board specific code: here "preboot" is
519 modified when the user holds down a certain
520 combination of keys on the (special) keyboard when
521 booting the systems
522
523- Serial Download Echo Mode:
524 CONFIG_LOADS_ECHO
525 If defined to 1, all characters received during a
526 serial download (using the "loads" command) are
527 echoed back. This might be needed by some terminal
528 emulations (like "cu"), but may as well just take
529 time on others. This setting #define's the initial
530 value of the "loads_echo" environment variable.
531
532- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
533 CONFIG_KGDB_BAUDRATE
534 Select one of the baudrates listed in
535 CFG_BAUDRATE_TABLE, see below.
536
537- Monitor Functions:
538 CONFIG_COMMANDS
539 Most monitor functions can be selected (or
540 de-selected) by adjusting the definition of
541 CONFIG_COMMANDS; to select individual functions,
542 #define CONFIG_COMMANDS by "OR"ing any of the
543 following values:
544
545 #define enables commands:
546 -------------------------
547 CFG_CMD_ASKENV * ask for env variable
548 CFG_CMD_BDI bdinfo
549 CFG_CMD_BEDBUG Include BedBug Debugger
550 CFG_CMD_BOOTD bootd
551 CFG_CMD_CACHE icache, dcache
552 CFG_CMD_CONSOLE coninfo
553 CFG_CMD_DATE * support for RTC, date/time...
554 CFG_CMD_DHCP DHCP support
555 CFG_CMD_ECHO * echo arguments
556 CFG_CMD_EEPROM * EEPROM read/write support
557 CFG_CMD_ELF bootelf, bootvx
558 CFG_CMD_ENV saveenv
559 CFG_CMD_FDC * Floppy Disk Support
wdenk2262cfe2002-11-18 00:14:45 +0000560 CFG_CMD_FDOS * Dos diskette Support
wdenkc6097192002-11-03 00:24:07 +0000561 CFG_CMD_FLASH flinfo, erase, protect
562 CFG_CMD_FPGA FPGA device initialization support
563 CFG_CMD_I2C * I2C serial bus support
564 CFG_CMD_IDE * IDE harddisk support
565 CFG_CMD_IMI iminfo
566 CFG_CMD_IMMAP * IMMR dump support
567 CFG_CMD_IRQ * irqinfo
568 CFG_CMD_KGDB * kgdb
569 CFG_CMD_LOADB loadb
570 CFG_CMD_LOADS loads
571 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
572 loop, mtest
573 CFG_CMD_MII MII utility commands
574 CFG_CMD_NET bootp, tftpboot, rarpboot
575 CFG_CMD_PCI * pciinfo
576 CFG_CMD_PCMCIA * PCMCIA support
577 CFG_CMD_REGINFO * Register dump
578 CFG_CMD_RUN run command in env variable
579 CFG_CMD_SCSI * SCSI Support
580 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
581 CFG_CMD_SPI * SPI serial bus support
582 CFG_CMD_USB * USB support
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
wdenk43d96162003-03-06 00:02:04 +0000604 (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.
wdenkc6097192002-11-03 00:24:07 +0000611
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 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
stroesec1551ea2003-04-04 15:53:41 +0000623- 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
wdenkc6097192002-11-03 00:24:07 +0000630- 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
wdenk1cb8e982003-03-06 21:55:29 +0000639 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
wdenkc6097192002-11-03 00:24:07 +0000640 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
wdenk3bac3512003-03-12 10:41:04 +0000641 CONFIG_RTC_DS164x - use Dallas DS164x RTC
wdenkc6097192002-11-03 00:24:07 +0000642
643- Timestamp Support:
644
wdenk43d96162003-03-06 00:02:04 +0000645 When CONFIG_TIMESTAMP is selected, the timestamp
646 (date and time) of an image is printed by image
647 commands like bootm or iminfo. This option is
648 automatically enabled when you select CFG_CMD_DATE .
wdenkc6097192002-11-03 00:24:07 +0000649
650- Partition Support:
651 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
652 and/or CONFIG_ISO_PARTITION
653
654 If IDE or SCSI support is enabled (CFG_CMD_IDE or
655 CFG_CMD_SCSI) you must configure support for at least
656 one partition type as well.
657
658- IDE Reset method:
659 CONFIG_IDE_RESET_ROUTINE
660
661 Set this to define that instead of a reset Pin, the
662 routine ide_set_reset(int idereset) will be used.
663
664- ATAPI Support:
665 CONFIG_ATAPI
666
667 Set this to enable ATAPI support.
668
669- SCSI Support:
670 At the moment only there is only support for the
671 SYM53C8XX SCSI controller; define
672 CONFIG_SCSI_SYM53C8XX to enable it.
673
674 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
675 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
676 CFG_SCSI_MAX_LUN] can be adjusted to define the
677 maximum numbers of LUNs, SCSI ID's and target
678 devices.
679 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
680
681- NETWORK Support (PCI):
682 CONFIG_EEPRO100
683 Support for Intel 82557/82559/82559ER chips.
684 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
685 write routine for first time initialisation.
686
687 CONFIG_TULIP
688 Support for Digital 2114x chips.
689 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
690 modem chip initialisation (KS8761/QS6611).
691
692 CONFIG_NATSEMI
693 Support for National dp83815 chips.
694
695 CONFIG_NS8382X
696 Support for National dp8382[01] gigabit chips.
697
698- USB Support:
699 At the moment only the UHCI host controller is
700 supported (PIP405, MIP405); define
701 CONFIG_USB_UHCI to enable it.
702 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
703 end define CONFIG_USB_STORAGE to enable the USB
704 storage devices.
705 Note:
706 Supported are USB Keyboards and USB Floppy drives
707 (TEAC FD-05PUB).
708
709- Keyboard Support:
710 CONFIG_ISA_KEYBOARD
711
712 Define this to enable standard (PC-Style) keyboard
713 support
714
715 CONFIG_I8042_KBD
716 Standard PC keyboard driver with US (is default) and
717 GERMAN key layout (switch via environment 'keymap=de') support.
718 Export function i8042_kbd_init, i8042_tstc and i8042_getc
719 for cfb_console. Supports cursor blinking.
720
721- Video support:
722 CONFIG_VIDEO
723
724 Define this to enable video support (for output to
725 video).
726
727 CONFIG_VIDEO_CT69000
728
729 Enable Chips & Technologies 69000 Video chip
730
731 CONFIG_VIDEO_SMI_LYNXEM
732 Enable Silicon Motion SMI 712/710/810 Video chip
733 Videomode are selected via environment 'videomode' with
734 standard LiLo mode numbers.
735 Following modes are supported (* is default):
736
wdenk43d96162003-03-06 00:02:04 +0000737 800x600 1024x768 1280x1024
738 256 (8bit) 303* 305 307
739 65536 (16bit) 314 317 31a
740 16,7 Mill (24bit) 315 318 31b
wdenkc6097192002-11-03 00:24:07 +0000741 (i.e. setenv videomode 317; saveenv; reset;)
742
stroesec1551ea2003-04-04 15:53:41 +0000743 CONFIG_VIDEO_SED13806
wdenk43d96162003-03-06 00:02:04 +0000744 Enable Epson SED13806 driver. This driver supports 8bpp
wdenka6c7ad22002-12-03 21:28:10 +0000745 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
746 or CONFIG_VIDEO_SED13806_16BPP
747
748
wdenkc6097192002-11-03 00:24:07 +0000749- LCD Support: CONFIG_LCD
750
751 Define this to enable LCD support (for output to LCD
752 display); also select one of the supported displays
753 by defining one of these:
754
755 CONFIG_NEC_NL6648AC33:
756
757 NEC NL6648AC33-18. Active, color, single scan.
758
759 CONFIG_NEC_NL6648BC20
760
761 NEC NL6648BC20-08. 6.5", 640x480.
762 Active, color, single scan.
763
764 CONFIG_SHARP_16x9
765
766 Sharp 320x240. Active, color, single scan.
767 It isn't 16x9, and I am not sure what it is.
768
769 CONFIG_SHARP_LQ64D341
770
771 Sharp LQ64D341 display, 640x480.
772 Active, color, single scan.
773
774 CONFIG_HLD1045
775
776 HLD1045 display, 640x480.
777 Active, color, single scan.
778
779 CONFIG_OPTREX_BW
780
781 Optrex CBL50840-2 NF-FW 99 22 M5
782 or
783 Hitachi LMG6912RPFC-00T
784 or
785 Hitachi SP14Q002
786
787 320x240. Black & white.
788
789 Normally display is black on white background; define
790 CFG_WHITE_ON_BLACK to get it inverted.
791
792- Ethernet address:
793 CONFIG_ETHADDR
794 CONFIG_ETH2ADDR
795 CONFIG_ETH3ADDR
796
797 Define a default value for ethernet address to use
798 for the respective ethernet interface, in case this
799 is not determined automatically.
800
801- IP address:
802 CONFIG_IPADDR
803
804 Define a default value for the IP address to use for
805 the default ethernet interface, in case this is not
806 determined through e.g. bootp.
807
808- Server IP address:
809 CONFIG_SERVERIP
810
811 Defines a default value for theIP address of a TFTP
812 server to contact when using the "tftboot" command.
813
814- BOOTP Recovery Mode:
815 CONFIG_BOOTP_RANDOM_DELAY
816
817 If you have many targets in a network that try to
818 boot using BOOTP, you may want to avoid that all
819 systems send out BOOTP requests at precisely the same
820 moment (which would happen for instance at recovery
821 from a power failure, when all systems will try to
822 boot, thus flooding the BOOTP server. Defining
823 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
824 inserted before sending out BOOTP requests. The
825 following delays are insterted then:
826
827 1st BOOTP request: delay 0 ... 1 sec
828 2nd BOOTP request: delay 0 ... 2 sec
829 3rd BOOTP request: delay 0 ... 4 sec
830 4th and following
831 BOOTP requests: delay 0 ... 8 sec
832
833- Status LED: CONFIG_STATUS_LED
834
835 Several configurations allow to display the current
836 status using a LED. For instance, the LED will blink
837 fast while running U-Boot code, stop blinking as
838 soon as a reply to a BOOTP request was received, and
839 start blinking slow once the Linux kernel is running
840 (supported by a status LED driver in the Linux
841 kernel). Defining CONFIG_STATUS_LED enables this
842 feature in U-Boot.
843
844- CAN Support: CONFIG_CAN_DRIVER
845
846 Defining CONFIG_CAN_DRIVER enables CAN driver support
847 on those systems that support this (optional)
848 feature, like the TQM8xxL modules.
849
850- I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
851
852 Enables I2C serial bus commands. If this is selected,
853 either CONFIG_HARD_I2C or CONFIG_SOFT_I2C must be defined
854 to include the appropriate I2C driver.
855
wdenk43d96162003-03-06 00:02:04 +0000856 See also: common/cmd_i2c.c for a description of the
857 command line interface.
wdenkc6097192002-11-03 00:24:07 +0000858
859
860 CONFIG_HARD_I2C
861
862 Selects the CPM hardware driver for I2C.
863
864 CONFIG_SOFT_I2C
865
866 Use software (aka bit-banging) driver instead of CPM
867 or similar hardware support for I2C. This is configured
868 via the following defines.
869
870 I2C_INIT
871
wdenk43d96162003-03-06 00:02:04 +0000872 (Optional). Any commands necessary to enable I2C
873 controller or configure ports.
wdenkc6097192002-11-03 00:24:07 +0000874
875 I2C_PORT
876
wdenk43d96162003-03-06 00:02:04 +0000877 (Only for MPC8260 CPU). The I/O port to use (the code
878 assumes both bits are on the same port). Valid values
879 are 0..3 for ports A..D.
wdenkc6097192002-11-03 00:24:07 +0000880
881 I2C_ACTIVE
882
883 The code necessary to make the I2C data line active
884 (driven). If the data line is open collector, this
885 define can be null.
886
887 I2C_TRISTATE
888
889 The code necessary to make the I2C data line tri-stated
890 (inactive). If the data line is open collector, this
891 define can be null.
892
893 I2C_READ
894
895 Code that returns TRUE if the I2C data line is high,
896 FALSE if it is low.
897
898 I2C_SDA(bit)
899
900 If <bit> is TRUE, sets the I2C data line high. If it
901 is FALSE, it clears it (low).
902
903 I2C_SCL(bit)
904
905 If <bit> is TRUE, sets the I2C clock line high. If it
906 is FALSE, it clears it (low).
907
908 I2C_DELAY
909
910 This delay is invoked four times per clock cycle so this
911 controls the rate of data transfer. The data rate thus
912 is 1 / (I2C_DELAY * 4).
913
wdenk47cd00f2003-03-06 13:39:27 +0000914 CFG_I2C_INIT_BOARD
915
916 When a board is reset during an i2c bus transfer
917 chips might think that the current transfer is still
918 in progress. On some boards it is possible to access
919 the i2c SCLK line directly, either by using the
920 processor pin as a GPIO or by having a second pin
921 connected to the bus. If this option is defined a
922 custom i2c_init_board() routine in boards/xxx/board.c
923 is run early in the boot sequence.
924
wdenkc6097192002-11-03 00:24:07 +0000925- SPI Support: CONFIG_SPI
926
927 Enables SPI driver (so far only tested with
928 SPI EEPROM, also an instance works with Crystal A/D and
929 D/As on the SACSng board)
930
931 CONFIG_SPI_X
932
933 Enables extended (16-bit) SPI EEPROM addressing.
934 (symmetrical to CONFIG_I2C_X)
935
936 CONFIG_SOFT_SPI
937
wdenk43d96162003-03-06 00:02:04 +0000938 Enables a software (bit-bang) SPI driver rather than
939 using hardware support. This is a general purpose
940 driver that only requires three general I/O port pins
941 (two outputs, one input) to function. If this is
942 defined, the board configuration must define several
943 SPI configuration items (port pins to use, etc). For
944 an example, see include/configs/sacsng.h.
wdenkc6097192002-11-03 00:24:07 +0000945
946- FPGA Support: CONFIG_FPGA_COUNT
947
wdenk43d96162003-03-06 00:02:04 +0000948 Specify the number of FPGA devices to support.
wdenkc6097192002-11-03 00:24:07 +0000949
wdenk43d96162003-03-06 00:02:04 +0000950 CONFIG_FPGA
wdenkc6097192002-11-03 00:24:07 +0000951
wdenk43d96162003-03-06 00:02:04 +0000952 Used to specify the types of FPGA devices. For
wdenkc6097192002-11-03 00:24:07 +0000953 example,
954 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
955
956 CFG_FPGA_PROG_FEEDBACK
957
wdenk43d96162003-03-06 00:02:04 +0000958 Enable printing of hash marks during FPGA
wdenkc6097192002-11-03 00:24:07 +0000959 configuration.
960
961 CFG_FPGA_CHECK_BUSY
962
wdenk43d96162003-03-06 00:02:04 +0000963 Enable checks on FPGA configuration interface busy
964 status by the configuration function. This option
965 will require a board or device specific function to
966 be written.
wdenkc6097192002-11-03 00:24:07 +0000967
968 CONFIG_FPGA_DELAY
969
wdenk43d96162003-03-06 00:02:04 +0000970 If defined, a function that provides delays in the
971 FPGA configuration driver.
wdenkc6097192002-11-03 00:24:07 +0000972
973 CFG_FPGA_CHECK_CTRLC
974
975 Allow Control-C to interrupt FPGA configuration
976
977 CFG_FPGA_CHECK_ERROR
978
wdenk43d96162003-03-06 00:02:04 +0000979 Check for configuration errors during FPGA bitfile
980 loading. For example, abort during Virtex II
981 configuration if the INIT_B line goes low (which
982 indicated a CRC error).
wdenkc6097192002-11-03 00:24:07 +0000983
984 CFG_FPGA_WAIT_INIT
985
wdenk43d96162003-03-06 00:02:04 +0000986 Maximum time to wait for the INIT_B line to deassert
987 after PROB_B has been deasserted during a Virtex II
988 FPGA configuration sequence. The default time is 500 mS.
wdenkc6097192002-11-03 00:24:07 +0000989
990 CFG_FPGA_WAIT_BUSY
991
wdenk43d96162003-03-06 00:02:04 +0000992 Maximum time to wait for BUSY to deassert during
993 Virtex II FPGA configuration. The default is 5 mS.
wdenkc6097192002-11-03 00:24:07 +0000994
995 CFG_FPGA_WAIT_CONFIG
996
wdenk43d96162003-03-06 00:02:04 +0000997 Time to wait after FPGA configuration. The default is
wdenkc6097192002-11-03 00:24:07 +0000998 200 mS.
999
1000- FPGA Support: CONFIG_FPGA_COUNT
1001
1002 Specify the number of FPGA devices to support.
1003
1004 CONFIG_FPGA
1005
1006 Used to specify the types of FPGA devices. For example,
1007 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1008
1009 CFG_FPGA_PROG_FEEDBACK
1010
1011 Enable printing of hash marks during FPGA configuration.
1012
1013 CFG_FPGA_CHECK_BUSY
1014
wdenk43d96162003-03-06 00:02:04 +00001015 Enable checks on FPGA configuration interface busy
1016 status by the configuration function. This option
1017 will require a board or device specific function to
1018 be written.
wdenkc6097192002-11-03 00:24:07 +00001019
1020 CONFIG_FPGA_DELAY
1021
1022 If defined, a function that provides delays in the FPGA
1023 configuration driver.
1024
1025 CFG_FPGA_CHECK_CTRLC
1026 Allow Control-C to interrupt FPGA configuration
1027
1028 CFG_FPGA_CHECK_ERROR
1029
wdenk43d96162003-03-06 00:02:04 +00001030 Check for configuration errors during FPGA bitfile
1031 loading. For example, abort during Virtex II
1032 configuration if the INIT_B line goes low (which
1033 indicated a CRC error).
wdenkc6097192002-11-03 00:24:07 +00001034
1035 CFG_FPGA_WAIT_INIT
1036
wdenk43d96162003-03-06 00:02:04 +00001037 Maximum time to wait for the INIT_B line to deassert
1038 after PROB_B has been deasserted during a Virtex II
1039 FPGA configuration sequence. The default time is 500
1040 mS.
wdenkc6097192002-11-03 00:24:07 +00001041
1042 CFG_FPGA_WAIT_BUSY
1043
wdenk43d96162003-03-06 00:02:04 +00001044 Maximum time to wait for BUSY to deassert during
1045 Virtex II FPGA configuration. The default is 5 mS.
wdenkc6097192002-11-03 00:24:07 +00001046
1047 CFG_FPGA_WAIT_CONFIG
1048
wdenk43d96162003-03-06 00:02:04 +00001049 Time to wait after FPGA configuration. The default is
1050 200 mS.
wdenkc6097192002-11-03 00:24:07 +00001051
1052- Configuration Management:
1053 CONFIG_IDENT_STRING
1054
wdenk43d96162003-03-06 00:02:04 +00001055 If defined, this string will be added to the U-Boot
1056 version information (U_BOOT_VERSION)
wdenkc6097192002-11-03 00:24:07 +00001057
1058- Vendor Parameter Protection:
1059
wdenk43d96162003-03-06 00:02:04 +00001060 U-Boot considers the values of the environment
1061 variables "serial#" (Board Serial Number) and
1062 "ethaddr" (Ethernet Address) to bb parameters that
1063 are set once by the board vendor / manufacturer, and
1064 protects these variables from casual modification by
1065 the user. Once set, these variables are read-only,
1066 and write or delete attempts are rejected. You can
1067 change this behviour:
wdenkc6097192002-11-03 00:24:07 +00001068
1069 If CONFIG_ENV_OVERWRITE is #defined in your config
1070 file, the write protection for vendor parameters is
wdenk47cd00f2003-03-06 13:39:27 +00001071 completely disabled. Anybody can change or delete
wdenkc6097192002-11-03 00:24:07 +00001072 these parameters.
1073
1074 Alternatively, if you #define _both_ CONFIG_ETHADDR
1075 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1076 ethernet address is installed in the environment,
1077 which can be changed exactly ONCE by the user. [The
1078 serial# is unaffected by this, i. e. it remains
1079 read-only.]
1080
1081- Protected RAM:
1082 CONFIG_PRAM
1083
1084 Define this variable to enable the reservation of
1085 "protected RAM", i. e. RAM which is not overwritten
1086 by U-Boot. Define CONFIG_PRAM to hold the number of
1087 kB you want to reserve for pRAM. You can overwrite
1088 this default value by defining an environment
1089 variable "pram" to the number of kB you want to
1090 reserve. Note that the board info structure will
1091 still show the full amount of RAM. If pRAM is
1092 reserved, a new environment variable "mem" will
1093 automatically be defined to hold the amount of
1094 remaining RAM in a form that can be passed as boot
1095 argument to Linux, for instance like that:
1096
1097 setenv bootargs ... mem=\$(mem)
1098 saveenv
1099
1100 This way you can tell Linux not to use this memory,
1101 either, which results in a memory region that will
1102 not be affected by reboots.
1103
1104 *WARNING* If your board configuration uses automatic
1105 detection of the RAM size, you must make sure that
1106 this memory test is non-destructive. So far, the
1107 following board configurations are known to be
1108 "pRAM-clean":
1109
1110 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1111 HERMES, IP860, RPXlite, LWMON, LANTEC,
1112 PCU_E, FLAGADM, TQM8260
1113
1114- Error Recovery:
1115 CONFIG_PANIC_HANG
1116
1117 Define this variable to stop the system in case of a
1118 fatal error, so that you have to reset it manually.
1119 This is probably NOT a good idea for an embedded
1120 system where you want to system to reboot
1121 automatically as fast as possible, but it may be
1122 useful during development since you can try to debug
1123 the conditions that lead to the situation.
1124
1125 CONFIG_NET_RETRY_COUNT
1126
wdenk43d96162003-03-06 00:02:04 +00001127 This variable defines the number of retries for
1128 network operations like ARP, RARP, TFTP, or BOOTP
1129 before giving up the operation. If not defined, a
1130 default value of 5 is used.
wdenkc6097192002-11-03 00:24:07 +00001131
1132- Command Interpreter:
1133 CFG_HUSH_PARSER
1134
1135 Define this variable to enable the "hush" shell (from
1136 Busybox) as command line interpreter, thus enabling
1137 powerful command line syntax like
1138 if...then...else...fi conditionals or `&&' and '||'
1139 constructs ("shell scripts").
1140
1141 If undefined, you get the old, much simpler behaviour
1142 with a somewhat smaller memory footprint.
1143
1144
1145 CFG_PROMPT_HUSH_PS2
1146
1147 This defines the secondary prompt string, which is
1148 printed when the command interpreter needs more input
1149 to complete a command. Usually "> ".
1150
1151 Note:
1152
wdenk43d96162003-03-06 00:02:04 +00001153 In the current implementation, the local variables
1154 space and global environment variables space are
1155 separated. Local variables are those you define by
1156 simply typing like `name=value'. To access a local
1157 variable later on, you have write `$name' or
1158 `${name}'; variable directly by typing say `$name' at
1159 the command prompt.
wdenkc6097192002-11-03 00:24:07 +00001160
wdenk43d96162003-03-06 00:02:04 +00001161 Global environment variables are those you use
1162 setenv/printenv to work with. To run a command stored
1163 in such a variable, you need to use the run command,
1164 and you must not use the '$' sign to access them.
wdenkc6097192002-11-03 00:24:07 +00001165
1166 To store commands and special characters in a
1167 variable, please use double quotation marks
1168 surrounding the whole text of the variable, instead
1169 of the backslashes before semicolons and special
1170 symbols.
1171
1172- Default Environment
1173 CONFIG_EXTRA_ENV_SETTINGS
1174
wdenk43d96162003-03-06 00:02:04 +00001175 Define this to contain any number of null terminated
1176 strings (variable = value pairs) that will be part of
1177 the default enviroment compiled into the boot image.
wdenk2262cfe2002-11-18 00:14:45 +00001178
wdenk43d96162003-03-06 00:02:04 +00001179 For example, place something like this in your
1180 board's config file:
wdenkc6097192002-11-03 00:24:07 +00001181
1182 #define CONFIG_EXTRA_ENV_SETTINGS \
1183 "myvar1=value1\0" \
1184 "myvar2=value2\0"
1185
wdenk43d96162003-03-06 00:02:04 +00001186 Warning: This method is based on knowledge about the
1187 internal format how the environment is stored by the
1188 U-Boot code. This is NOT an official, exported
1189 interface! Although it is unlikely that this format
1190 will change soon, but there is no guarantee either.
wdenkc6097192002-11-03 00:24:07 +00001191 You better know what you are doing here.
1192
wdenk43d96162003-03-06 00:02:04 +00001193 Note: overly (ab)use of the default environment is
1194 discouraged. Make sure to check other ways to preset
1195 the environment like the autoscript function or the
1196 boot command first.
wdenkc6097192002-11-03 00:24:07 +00001197
1198- Show boot progress
1199 CONFIG_SHOW_BOOT_PROGRESS
1200
wdenk43d96162003-03-06 00:02:04 +00001201 Defining this option allows to add some board-
1202 specific code (calling a user-provided function
1203 "show_boot_progress(int)") that enables you to show
1204 the system's boot progress on some display (for
1205 example, some LED's) on your board. At the moment,
1206 the following checkpoints are implemented:
wdenkc6097192002-11-03 00:24:07 +00001207
1208 Arg Where When
1209 1 common/cmd_bootm.c before attempting to boot an image
1210 -1 common/cmd_bootm.c Image header has bad magic number
1211 2 common/cmd_bootm.c Image header has correct magic number
1212 -2 common/cmd_bootm.c Image header has bad checksum
1213 3 common/cmd_bootm.c Image header has correct checksum
1214 -3 common/cmd_bootm.c Image data has bad checksum
1215 4 common/cmd_bootm.c Image data has correct checksum
1216 -4 common/cmd_bootm.c Image is for unsupported architecture
1217 5 common/cmd_bootm.c Architecture check OK
1218 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1219 6 common/cmd_bootm.c Image Type check OK
1220 -6 common/cmd_bootm.c gunzip uncompression error
1221 -7 common/cmd_bootm.c Unimplemented compression type
1222 7 common/cmd_bootm.c Uncompression OK
1223 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1224 8 common/cmd_bootm.c Image Type check OK
1225 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1226 9 common/cmd_bootm.c Start initial ramdisk verification
1227 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1228 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1229 10 common/cmd_bootm.c Ramdisk header is OK
1230 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1231 11 common/cmd_bootm.c Ramdisk data has correct checksum
1232 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1233 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1234 13 common/cmd_bootm.c Start multifile image verification
1235 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1236 15 common/cmd_bootm.c All preparation done, transferring control to OS
1237
1238 -1 common/cmd_doc.c Bad usage of "doc" command
1239 -1 common/cmd_doc.c No boot device
1240 -1 common/cmd_doc.c Unknown Chip ID on boot device
1241 -1 common/cmd_doc.c Read Error on boot device
1242 -1 common/cmd_doc.c Image header has bad magic number
1243
1244 -1 common/cmd_ide.c Bad usage of "ide" command
1245 -1 common/cmd_ide.c No boot device
1246 -1 common/cmd_ide.c Unknown boot device
1247 -1 common/cmd_ide.c Unknown partition table
1248 -1 common/cmd_ide.c Invalid partition type
1249 -1 common/cmd_ide.c Read Error on boot device
1250 -1 common/cmd_ide.c Image header has bad magic number
1251
1252 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1253
1254
1255Modem Support:
1256--------------
1257
wdenk85ec0bc2003-03-31 16:34:49 +00001258[so far only for SMDK2400 and TRAB boards]
wdenkc6097192002-11-03 00:24:07 +00001259
1260- Modem support endable:
1261 CONFIG_MODEM_SUPPORT
1262
1263- RTS/CTS Flow control enable:
1264 CONFIG_HWFLOW
1265
1266- Modem debug support:
1267 CONFIG_MODEM_SUPPORT_DEBUG
1268
wdenk43d96162003-03-06 00:02:04 +00001269 Enables debugging stuff (char screen[1024], dbg())
1270 for modem support. Useful only with BDI2000.
wdenkc6097192002-11-03 00:24:07 +00001271
1272- General:
1273
wdenk43d96162003-03-06 00:02:04 +00001274 In the target system modem support is enabled when a
1275 specific key (key combination) is pressed during
1276 power-on. Otherwise U-Boot will boot normally
1277 (autoboot). The key_pressed() fuction is called from
1278 board_init(). Currently key_pressed() is a dummy
1279 function, returning 1 and thus enabling modem
1280 initialization.
wdenkc6097192002-11-03 00:24:07 +00001281
wdenk43d96162003-03-06 00:02:04 +00001282 If there are no modem init strings in the
1283 environment, U-Boot proceed to autoboot; the
1284 previous output (banner, info printfs) will be
1285 supressed, though.
wdenkc6097192002-11-03 00:24:07 +00001286
1287 See also: doc/README.Modem
1288
1289
1290
1291
1292Configuration Settings:
1293-----------------------
1294
1295- CFG_LONGHELP: Defined when you want long help messages included;
1296 undefine this when you're short of memory.
1297
1298- CFG_PROMPT: This is what U-Boot prints on the console to
1299 prompt for user input.
1300
1301- CFG_CBSIZE: Buffer size for input from the Console
1302
1303- CFG_PBSIZE: Buffer size for Console output
1304
1305- CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1306
1307- CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1308 the application (usually a Linux kernel) when it is
1309 booted
1310
1311- CFG_BAUDRATE_TABLE:
1312 List of legal baudrate settings for this board.
1313
1314- CFG_CONSOLE_INFO_QUIET
1315 Suppress display of console information at boot.
1316
1317- CFG_CONSOLE_IS_IN_ENV
1318 If the board specific function
1319 extern int overwrite_console (void);
1320 returns 1, the stdin, stderr and stdout are switched to the
1321 serial port, else the settings in the environment are used.
1322
1323- CFG_CONSOLE_OVERWRITE_ROUTINE
1324 Enable the call to overwrite_console().
1325
1326- CFG_CONSOLE_ENV_OVERWRITE
1327 Enable overwrite of previous console environment settings.
1328
1329- CFG_MEMTEST_START, CFG_MEMTEST_END:
1330 Begin and End addresses of the area used by the
1331 simple memory test.
1332
1333- CFG_ALT_MEMTEST:
1334 Enable an alternate, more extensive memory test.
1335
1336- CFG_TFTP_LOADADDR:
1337 Default load address for network file downloads
1338
1339- CFG_LOADS_BAUD_CHANGE:
1340 Enable temporary baudrate change while serial download
1341
1342- CFG_SDRAM_BASE:
1343 Physical start address of SDRAM. _Must_ be 0 here.
1344
1345- CFG_MBIO_BASE:
1346 Physical start address of Motherboard I/O (if using a
1347 Cogent motherboard)
1348
1349- CFG_FLASH_BASE:
1350 Physical start address of Flash memory.
1351
1352- CFG_MONITOR_BASE:
1353 Physical start address of boot monitor code (set by
1354 make config files to be same as the text base address
1355 (TEXT_BASE) used when linking) - same as
1356 CFG_FLASH_BASE when booting from flash.
1357
1358- CFG_MONITOR_LEN:
1359 Size of memory reserved for monitor code
1360
1361- CFG_MALLOC_LEN:
1362 Size of DRAM reserved for malloc() use.
1363
1364- CFG_BOOTMAPSZ:
1365 Maximum size of memory mapped by the startup code of
1366 the Linux kernel; all data that must be processed by
1367 the Linux kernel (bd_info, boot arguments, eventually
1368 initrd image) must be put below this limit.
1369
1370- CFG_MAX_FLASH_BANKS:
1371 Max number of Flash memory banks
1372
1373- CFG_MAX_FLASH_SECT:
1374 Max number of sectors on a Flash chip
1375
1376- CFG_FLASH_ERASE_TOUT:
1377 Timeout for Flash erase operations (in ms)
1378
1379- CFG_FLASH_WRITE_TOUT:
1380 Timeout for Flash write operations (in ms)
1381
1382- CFG_DIRECT_FLASH_TFTP:
1383
1384 Enable TFTP transfers directly to flash memory;
1385 without this option such a download has to be
1386 performed in two steps: (1) download to RAM, and (2)
1387 copy from RAM to flash.
1388
1389 The two-step approach is usually more reliable, since
1390 you can check if the download worked before you erase
1391 the flash, but in some situations (when sytem RAM is
1392 too limited to allow for a tempory copy of the
1393 downloaded image) this option may be very useful.
1394
1395- CFG_FLASH_CFI:
wdenk43d96162003-03-06 00:02:04 +00001396 Define if the flash driver uses extra elements in the
1397 common flash structure for storing flash geometry
wdenkc6097192002-11-03 00:24:07 +00001398
1399The following definitions that deal with the placement and management
1400of environment data (variable area); in general, we support the
1401following configurations:
1402
1403- CFG_ENV_IS_IN_FLASH:
1404
1405 Define this if the environment is in flash memory.
1406
1407 a) The environment occupies one whole flash sector, which is
1408 "embedded" in the text segment with the U-Boot code. This
1409 happens usually with "bottom boot sector" or "top boot
1410 sector" type flash chips, which have several smaller
1411 sectors at the start or the end. For instance, such a
1412 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1413 such a case you would place the environment in one of the
1414 4 kB sectors - with U-Boot code before and after it. With
1415 "top boot sector" type flash chips, you would put the
1416 environment in one of the last sectors, leaving a gap
1417 between U-Boot and the environment.
1418
1419 - CFG_ENV_OFFSET:
1420
1421 Offset of environment data (variable area) to the
1422 beginning of flash memory; for instance, with bottom boot
1423 type flash chips the second sector can be used: the offset
1424 for this sector is given here.
1425
1426 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1427
1428 - CFG_ENV_ADDR:
1429
1430 This is just another way to specify the start address of
1431 the flash sector containing the environment (instead of
1432 CFG_ENV_OFFSET).
1433
1434 - CFG_ENV_SECT_SIZE:
1435
1436 Size of the sector containing the environment.
1437
1438
1439 b) Sometimes flash chips have few, equal sized, BIG sectors.
1440 In such a case you don't want to spend a whole sector for
1441 the environment.
1442
1443 - CFG_ENV_SIZE:
1444
1445 If you use this in combination with CFG_ENV_IS_IN_FLASH
1446 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1447 of this flash sector for the environment. This saves
1448 memory for the RAM copy of the environment.
1449
1450 It may also save flash memory if you decide to use this
1451 when your environment is "embedded" within U-Boot code,
1452 since then the remainder of the flash sector could be used
1453 for U-Boot code. It should be pointed out that this is
1454 STRONGLY DISCOURAGED from a robustness point of view:
1455 updating the environment in flash makes it always
1456 necessary to erase the WHOLE sector. If something goes
1457 wrong before the contents has been restored from a copy in
1458 RAM, your target system will be dead.
1459
1460 - CFG_ENV_ADDR_REDUND
1461 CFG_ENV_SIZE_REDUND
1462
wdenk43d96162003-03-06 00:02:04 +00001463 These settings describe a second storage area used to hold
1464 a redundand copy of the environment data, so that there is
wdenk3e386912003-04-05 00:53:31 +00001465 a valid backup copy in case there is a power failure during
wdenk43d96162003-03-06 00:02:04 +00001466 a "saveenv" operation.
wdenkc6097192002-11-03 00:24:07 +00001467
1468BE CAREFUL! Any changes to the flash layout, and some changes to the
1469source code will make it necessary to adapt <board>/u-boot.lds*
1470accordingly!
1471
1472
1473- CFG_ENV_IS_IN_NVRAM:
1474
1475 Define this if you have some non-volatile memory device
1476 (NVRAM, battery buffered SRAM) which you want to use for the
1477 environment.
1478
1479 - CFG_ENV_ADDR:
1480 - CFG_ENV_SIZE:
1481
1482 These two #defines are used to determin the memory area you
1483 want to use for environment. It is assumed that this memory
1484 can just be read and written to, without any special
1485 provision.
1486
1487BE CAREFUL! The first access to the environment happens quite early
1488in U-Boot initalization (when we try to get the setting of for the
1489console baudrate). You *MUST* have mappend your NVRAM area then, or
1490U-Boot will hang.
1491
1492Please note that even with NVRAM we still use a copy of the
1493environment in RAM: we could work on NVRAM directly, but we want to
1494keep settings there always unmodified except somebody uses "saveenv"
1495to save the current settings.
1496
1497
1498- CFG_ENV_IS_IN_EEPROM:
1499
1500 Use this if you have an EEPROM or similar serial access
1501 device and a driver for it.
1502
1503 - CFG_ENV_OFFSET:
1504 - CFG_ENV_SIZE:
1505
1506 These two #defines specify the offset and size of the
1507 environment area within the total memory of your EEPROM.
1508
1509 - CFG_I2C_EEPROM_ADDR:
1510 If defined, specified the chip address of the EEPROM device.
1511 The default address is zero.
1512
1513 - CFG_EEPROM_PAGE_WRITE_BITS:
1514 If defined, the number of bits used to address bytes in a
1515 single page in the EEPROM device. A 64 byte page, for example
1516 would require six bits.
1517
1518 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1519 If defined, the number of milliseconds to delay between
1520 page writes. The default is zero milliseconds.
1521
1522 - CFG_I2C_EEPROM_ADDR_LEN:
1523 The length in bytes of the EEPROM memory array address. Note
1524 that this is NOT the chip address length!
1525
1526 - CFG_EEPROM_SIZE:
1527 The size in bytes of the EEPROM device.
1528
wdenkc6097192002-11-03 00:24:07 +00001529
1530- CFG_SPI_INIT_OFFSET
1531
1532 Defines offset to the initial SPI buffer area in DPRAM. The
1533 area is used at an early stage (ROM part) if the environment
1534 is configured to reside in the SPI EEPROM: We need a 520 byte
1535 scratch DPRAM area. It is used between the two initialization
1536 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1537 to be a good choice since it makes it far enough from the
1538 start of the data area as well as from the stack pointer.
1539
1540Please note that the environment is read-only as long as the monitor
1541has been relocated to RAM and a RAM copy of the environment has been
1542created; also, when using EEPROM you will have to use getenv_r()
1543until then to read environment variables.
1544
wdenk85ec0bc2003-03-31 16:34:49 +00001545The environment is protected by a CRC32 checksum. Before the monitor
1546is relocated into RAM, as a result of a bad CRC you will be working
1547with the compiled-in default environment - *silently*!!! [This is
1548necessary, because the first environment variable we need is the
1549"baudrate" setting for the console - if we have a bad CRC, we don't
1550have any device yet where we could complain.]
wdenkc6097192002-11-03 00:24:07 +00001551
1552Note: once the monitor has been relocated, then it will complain if
1553the default environment is used; a new CRC is computed as soon as you
wdenk85ec0bc2003-03-31 16:34:49 +00001554use the "saveenv" command to store a valid environment.
wdenkc6097192002-11-03 00:24:07 +00001555
1556
wdenkc6097192002-11-03 00:24:07 +00001557Low Level (hardware related) configuration options:
wdenkdc7c9a12003-03-26 06:55:25 +00001558---------------------------------------------------
wdenkc6097192002-11-03 00:24:07 +00001559
1560- CFG_CACHELINE_SIZE:
1561 Cache Line Size of the CPU.
1562
1563- CFG_DEFAULT_IMMR:
1564 Default address of the IMMR after system reset.
1565 Needed on some 8260 systems (MPC8260ADS and RPXsuper)
1566 to be able to adjust the position of the IMMR
1567 register after a reset.
1568
wdenk7f6c2cb2002-11-10 22:06:23 +00001569- Floppy Disk Support:
1570 CFG_FDC_DRIVE_NUMBER
1571
1572 the default drive number (default value 0)
1573
1574 CFG_ISA_IO_STRIDE
1575
1576 defines the spacing between fdc chipset registers
1577 (default value 1)
1578
1579 CFG_ISA_IO_OFFSET
1580
wdenk43d96162003-03-06 00:02:04 +00001581 defines the offset of register from address. It
1582 depends on which part of the data bus is connected to
1583 the fdc chipset. (default value 0)
wdenk7f6c2cb2002-11-10 22:06:23 +00001584
wdenk43d96162003-03-06 00:02:04 +00001585 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1586 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1587 default value.
wdenk7f6c2cb2002-11-10 22:06:23 +00001588
wdenk43d96162003-03-06 00:02:04 +00001589 if CFG_FDC_HW_INIT is defined, then the function
1590 fdc_hw_init() is called at the beginning of the FDC
1591 setup. fdc_hw_init() must be provided by the board
1592 source code. It is used to make hardware dependant
1593 initializations.
wdenk7f6c2cb2002-11-10 22:06:23 +00001594
wdenkc6097192002-11-03 00:24:07 +00001595- CFG_IMMR: Physical address of the Internal Memory Mapped
1596 Register; DO NOT CHANGE! (11-4)
1597 [MPC8xx systems only]
1598
1599- CFG_INIT_RAM_ADDR:
1600
1601 Start address of memory area tha can be used for
1602 initial data and stack; please note that this must be
1603 writable memory that is working WITHOUT special
1604 initialization, i. e. you CANNOT use normal RAM which
1605 will become available only after programming the
1606 memory controller and running certain initialization
1607 sequences.
1608
1609 U-Boot uses the following memory types:
1610 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1611 - MPC824X: data cache
1612 - PPC4xx: data cache
1613
wdenk85ec0bc2003-03-31 16:34:49 +00001614- CFG_GBL_DATA_OFFSET:
wdenkc6097192002-11-03 00:24:07 +00001615
1616 Offset of the initial data structure in the memory
1617 area defined by CFG_INIT_RAM_ADDR. Usually
wdenk85ec0bc2003-03-31 16:34:49 +00001618 CFG_GBL_DATA_OFFSET is chosen such that the initial
wdenkc6097192002-11-03 00:24:07 +00001619 data is located at the end of the available space
1620 (sometimes written as (CFG_INIT_RAM_END -
1621 CFG_INIT_DATA_SIZE), and the initial stack is just
1622 below that area (growing from (CFG_INIT_RAM_ADDR +
wdenk85ec0bc2003-03-31 16:34:49 +00001623 CFG_GBL_DATA_OFFSET) downward.
wdenkc6097192002-11-03 00:24:07 +00001624
1625 Note:
1626 On the MPC824X (or other systems that use the data
1627 cache for initial memory) the address chosen for
1628 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1629 point to an otherwise UNUSED address space between
1630 the top of RAM and the start of the PCI space.
1631
1632- CFG_SIUMCR: SIU Module Configuration (11-6)
1633
1634- CFG_SYPCR: System Protection Control (11-9)
1635
1636- CFG_TBSCR: Time Base Status and Control (11-26)
1637
1638- CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1639
1640- CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1641
1642- CFG_SCCR: System Clock and reset Control Register (15-27)
1643
1644- CFG_OR_TIMING_SDRAM:
1645 SDRAM timing
1646
1647- CFG_MAMR_PTA:
1648 periodic timer for refresh
1649
1650- CFG_DER: Debug Event Register (37-47)
1651
1652- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1653 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1654 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1655 CFG_BR1_PRELIM:
1656 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1657
1658- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1659 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1660 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1661 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1662
1663- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1664 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1665 Machine Mode Register and Memory Periodic Timer
1666 Prescaler definitions (SDRAM timing)
1667
1668- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1669 enable I2C microcode relocation patch (MPC8xx);
1670 define relocation offset in DPRAM [DSP2]
1671
1672- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1673 enable SPI microcode relocation patch (MPC8xx);
1674 define relocation offset in DPRAM [SCC4]
1675
1676- CFG_USE_OSCCLK:
1677 Use OSCM clock mode on MBX8xx board. Be careful,
1678 wrong setting might damage your board. Read
1679 doc/README.MBX before setting this variable!
1680
wdenkea909b72002-11-21 23:11:29 +00001681- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
wdenk43d96162003-03-06 00:02:04 +00001682 Offset of the bootmode word in DPRAM used by post
1683 (Power On Self Tests). This definition overrides
1684 #define'd default value in commproc.h resp.
1685 cpm_8260.h.
wdenkea909b72002-11-21 23:11:29 +00001686
wdenkc6097192002-11-03 00:24:07 +00001687Building the Software:
1688======================
1689
1690Building U-Boot has been tested in native PPC environments (on a
1691PowerBook G3 running LinuxPPC 2000) and in cross environments
1692(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1693NetBSD 1.5 on x86).
1694
1695If you are not using a native PPC environment, it is assumed that you
1696have the GNU cross compiling tools available in your path and named
1697with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1698you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1699the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1700change it to:
1701
1702 CROSS_COMPILE = ppc_4xx-
1703
1704
1705U-Boot is intended to be simple to build. After installing the
1706sources you must configure U-Boot for one specific board type. This
1707is done by typing:
1708
1709 make NAME_config
1710
1711where "NAME_config" is the name of one of the existing
1712configurations; the following names are supported:
1713
1714 ADCIOP_config GTH_config TQM850L_config
1715 ADS860_config IP860_config TQM855L_config
1716 AR405_config IVML24_config TQM860L_config
1717 CANBT_config IVMS8_config WALNUT405_config
1718 CPCI405_config LANTEC_config cogent_common_config
1719 CPCIISER4_config MBX_config cogent_mpc8260_config
1720 CU824_config MBX860T_config cogent_mpc8xx_config
1721 ESTEEM192E_config RPXlite_config hermes_config
1722 ETX094_config RPXsuper_config hymod_config
1723 FADS823_config SM850_config lwmon_config
1724 FADS850SAR_config SPD823TS_config pcu_e_config
1725 FADS860T_config SXNI855T_config rsdproto_config
1726 FPS850L_config Sandpoint8240_config sbc8260_config
1727 GENIETV_config TQM823L_config PIP405_config
wdenk384ae022002-11-05 00:17:55 +00001728 GEN860T_config EBONY_config FPS860L_config
wdenk0db5bca2003-03-31 17:27:09 +00001729 ELPT860_config cmi_mpc5xx_config
wdenkc6097192002-11-03 00:24:07 +00001730
1731Note: for some board special configuration names may exist; check if
1732 additional information is available from the board vendor; for
1733 instance, the TQM8xxL systems run normally at 50 MHz and use a
1734 SCC for 10baseT ethernet; there are also systems with 80 MHz
1735 CPU clock, and an optional Fast Ethernet module is available
1736 for CPU's with FEC. You can select such additional "features"
1737 when chosing the configuration, i. e.
1738
1739 make TQM860L_config
1740 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1741
1742 make TQM860L_FEC_config
1743 - will configure for a TQM860L at 50MHz with FEC for ethernet
1744
1745 make TQM860L_80MHz_config
1746 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1747 interface
1748
1749 make TQM860L_FEC_80MHz_config
1750 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1751
1752 make TQM823L_LCD_config
1753 - will configure for a TQM823L with U-Boot console on LCD
1754
1755 make TQM823L_LCD_80MHz_config
1756 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1757
1758 etc.
1759
1760
1761
wdenk24ee89b2002-11-03 17:56:27 +00001762Finally, type "make all", and you should get some working U-Boot
wdenkc6097192002-11-03 00:24:07 +00001763images ready for downlod to / installation on your system:
1764
1765- "u-boot.bin" is a raw binary image
1766- "u-boot" is an image in ELF binary format
1767- "u-boot.srec" is in Motorola S-Record format
1768
1769
1770Please be aware that the Makefiles assume you are using GNU make, so
1771for instance on NetBSD you might need to use "gmake" instead of
1772native "make".
1773
1774
1775If the system board that you have is not listed, then you will need
1776to port U-Boot to your hardware platform. To do this, follow these
1777steps:
1778
17791. Add a new configuration option for your board to the toplevel
wdenk85ec0bc2003-03-31 16:34:49 +00001780 "Makefile" and to the "MAKEALL" script, using the existing
1781 entries as examples. Note that here and at many other places
1782 boards and other names are listed alphabetically sorted. Please
1783 keep this order.
wdenkc6097192002-11-03 00:24:07 +000017842. Create a new directory to hold your board specific code. Add any
wdenk85ec0bc2003-03-31 16:34:49 +00001785 files you need. In your board directory, you will need at least
1786 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
17873. Create a new configuration file "include/configs/<board>.h" for
1788 your board
wdenkc6097192002-11-03 00:24:07 +000017893. If you're porting U-Boot to a new CPU, then also create a new
1790 directory to hold your CPU specific code. Add any files you need.
wdenk85ec0bc2003-03-31 16:34:49 +000017914. Run "make <board>_config" with your new name.
wdenkc6097192002-11-03 00:24:07 +000017925. Type "make", and you should get a working "u-boot.srec" file
1793 to be installed on your target system.
wdenk85ec0bc2003-03-31 16:34:49 +000017946. Debug and solve any problems that might arise.
wdenkc6097192002-11-03 00:24:07 +00001795 [Of course, this last step is much harder than it sounds.]
1796
1797
1798Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1799==============================================================
1800
1801If you have modified U-Boot sources (for instance added a new board
1802or support for new devices, a new CPU, etc.) you are expected to
1803provide feedback to the other developers. The feedback normally takes
1804the form of a "patch", i. e. a context diff against a certain (latest
1805official or latest in CVS) version of U-Boot sources.
1806
1807But before you submit such a patch, please verify that your modifi-
1808cation did not break existing code. At least make sure that *ALL* of
1809the supported boards compile WITHOUT ANY compiler warnings. To do so,
1810just run the "MAKEALL" script, which will configure and build U-Boot
1811for ALL supported system. Be warned, this will take a while. You can
1812select which (cross) compiler to use py passing a `CROSS_COMPILE'
1813environment variable to the script, i. e. to use the cross tools from
1814MontaVista's Hard Hat Linux you can type
1815
1816 CROSS_COMPILE=ppc_8xx- MAKEALL
1817
1818or to build on a native PowerPC system you can type
1819
1820 CROSS_COMPILE=' ' MAKEALL
1821
1822See also "U-Boot Porting Guide" below.
1823
1824
1825
1826Monitor Commands - Overview:
1827============================
1828
1829go - start application at address 'addr'
1830run - run commands in an environment variable
1831bootm - boot application image from memory
1832bootp - boot image via network using BootP/TFTP protocol
1833tftpboot- boot image via network using TFTP protocol
1834 and env variables "ipaddr" and "serverip"
1835 (and eventually "gatewayip")
1836rarpboot- boot image via network using RARP/TFTP protocol
1837diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
1838loads - load S-Record file over serial line
1839loadb - load binary file over serial line (kermit mode)
1840md - memory display
1841mm - memory modify (auto-incrementing)
1842nm - memory modify (constant address)
1843mw - memory write (fill)
1844cp - memory copy
1845cmp - memory compare
1846crc32 - checksum calculation
1847imd - i2c memory display
1848imm - i2c memory modify (auto-incrementing)
1849inm - i2c memory modify (constant address)
1850imw - i2c memory write (fill)
1851icrc32 - i2c checksum calculation
1852iprobe - probe to discover valid I2C chip addresses
1853iloop - infinite loop on address range
1854isdram - print SDRAM configuration information
1855sspi - SPI utility commands
1856base - print or set address offset
1857printenv- print environment variables
1858setenv - set environment variables
1859saveenv - save environment variables to persistent storage
1860protect - enable or disable FLASH write protection
1861erase - erase FLASH memory
1862flinfo - print FLASH memory information
1863bdinfo - print Board Info structure
1864iminfo - print header information for application image
1865coninfo - print console devices and informations
1866ide - IDE sub-system
1867loop - infinite loop on address range
1868mtest - simple RAM test
1869icache - enable or disable instruction cache
1870dcache - enable or disable data cache
1871reset - Perform RESET of the CPU
1872echo - echo args to console
1873version - print monitor version
1874help - print online help
1875? - alias for 'help'
1876
1877
1878Monitor Commands - Detailed Description:
1879========================================
1880
1881TODO.
1882
1883For now: just type "help <command>".
1884
1885
1886Environment Variables:
1887======================
1888
1889U-Boot supports user configuration using Environment Variables which
1890can be made persistent by saving to Flash memory.
1891
1892Environment Variables are set using "setenv", printed using
1893"printenv", and saved to Flash using "saveenv". Using "setenv"
1894without a value can be used to delete a variable from the
1895environment. As long as you don't save the environment you are
1896working with an in-memory copy. In case the Flash area containing the
1897environment is erased by accident, a default environment is provided.
1898
1899Some configuration options can be set using Environment Variables:
1900
1901 baudrate - see CONFIG_BAUDRATE
1902
1903 bootdelay - see CONFIG_BOOTDELAY
1904
1905 bootcmd - see CONFIG_BOOTCOMMAND
1906
1907 bootargs - Boot arguments when booting an RTOS image
1908
1909 bootfile - Name of the image to load with TFTP
1910
1911 autoload - if set to "no" (any string beginning with 'n'),
1912 "bootp" will just load perform a lookup of the
1913 configuration from the BOOTP server, but not try to
1914 load any image using TFTP
1915
1916 autostart - if set to "yes", an image loaded using the "bootp",
1917 "rarpboot", "tftpboot" or "diskboot" commands will
1918 be automatically started (by internally calling
1919 "bootm")
1920
1921 initrd_high - restrict positioning of initrd images:
1922 If this variable is not set, initrd images will be
1923 copied to the highest possible address in RAM; this
1924 is usually what you want since it allows for
1925 maximum initrd size. If for some reason you want to
1926 make sure that the initrd image is loaded below the
1927 CFG_BOOTMAPSZ limit, you can set this environment
1928 variable to a value of "no" or "off" or "0".
1929 Alternatively, you can set it to a maximum upper
1930 address to use (U-Boot will still check that it
1931 does not overwrite the U-Boot stack and data).
1932
1933 For instance, when you have a system with 16 MB
1934 RAM, and want to reseve 4 MB from use by Linux,
1935 you can do this by adding "mem=12M" to the value of
1936 the "bootargs" variable. However, now you must make
1937 sure, that the initrd image is placed in the first
1938 12 MB as well - this can be done with
1939
1940 setenv initrd_high 00c00000
1941
1942 ipaddr - IP address; needed for tftpboot command
1943
1944 loadaddr - Default load address for commands like "bootp",
wdenkdc7c9a12003-03-26 06:55:25 +00001945 "rarpboot", "tftpboot", "loadb" or "diskboot"
wdenkc6097192002-11-03 00:24:07 +00001946
1947 loads_echo - see CONFIG_LOADS_ECHO
1948
1949 serverip - TFTP server IP address; needed for tftpboot command
1950
1951 bootretry - see CONFIG_BOOT_RETRY_TIME
1952
1953 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
1954
1955 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
1956
1957
1958The following environment variables may be used and automatically
1959updated by the network boot commands ("bootp" and "rarpboot"),
1960depending the information provided by your boot server:
1961
1962 bootfile - see above
1963 dnsip - IP address of your Domain Name Server
1964 gatewayip - IP address of the Gateway (Router) to use
1965 hostname - Target hostname
1966 ipaddr - see above
1967 netmask - Subnet Mask
1968 rootpath - Pathname of the root filesystem on the NFS server
1969 serverip - see above
1970
1971
1972There are two special Environment Variables:
1973
1974 serial# - contains hardware identification information such
1975 as type string and/or serial number
1976 ethaddr - Ethernet address
1977
1978These variables can be set only once (usually during manufacturing of
1979the board). U-Boot refuses to delete or overwrite these variables
1980once they have been set once.
1981
1982
stroesec1551ea2003-04-04 15:53:41 +00001983Further special Environment Variables:
1984
1985 ver - Contains the U-Boot version string as printed
1986 with the "version" command. This variable is
1987 readonly (see CONFIG_VERSION_VARIABLE).
1988
1989
wdenkc6097192002-11-03 00:24:07 +00001990Please note that changes to some configuration parameters may take
1991only effect after the next boot (yes, that's just like Windoze :-).
1992
1993
1994Note for Redundant Ethernet Interfaces:
1995=======================================
1996
1997Some boards come with redundand ethernet interfaces; U-Boot supports
1998such configurations and is capable of automatic selection of a
1999"working" interface when needed. MAC assignemnt works as follows:
2000
2001Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2002MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2003"eth1addr" (=>eth1), "eth2addr", ...
2004
2005If the network interface stores some valid MAC address (for instance
2006in SROM), this is used as default address if there is NO correspon-
2007ding setting in the environment; if the corresponding environment
2008variable is set, this overrides the settings in the card; that means:
2009
2010o If the SROM has a valid MAC address, and there is no address in the
2011 environment, the SROM's address is used.
2012
2013o If there is no valid address in the SROM, and a definition in the
2014 environment exists, then the value from the environment variable is
2015 used.
2016
2017o If both the SROM and the environment contain a MAC address, and
2018 both addresses are the same, this MAC address is used.
2019
2020o If both the SROM and the environment contain a MAC address, and the
2021 addresses differ, the value from the environment is used and a
2022 warning is printed.
2023
2024o If neither SROM nor the environment contain a MAC address, an error
2025 is raised.
2026
2027
2028
2029Image Formats:
2030==============
2031
2032The "boot" commands of this monitor operate on "image" files which
2033can be basicly anything, preceeded by a special header; see the
2034definitions in include/image.h for details; basicly, the header
2035defines the following image properties:
2036
2037* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2038 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2039 LynxOS, pSOS, QNX;
2040 Currently supported: Linux, NetBSD, VxWorks, QNX).
2041* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2042 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2043 Currently supported: PowerPC).
2044* Compression Type (Provisions for uncompressed, gzip, bzip2;
2045 Currently supported: uncompressed, gzip).
2046* Load Address
2047* Entry Point
2048* Image Name
2049* Image Timestamp
2050
2051The header is marked by a special Magic Number, and both the header
2052and the data portions of the image are secured against corruption by
2053CRC32 checksums.
2054
2055
2056Linux Support:
2057==============
2058
2059Although U-Boot should support any OS or standalone application
2060easily, Linux has always been in the focus during the design of
2061U-Boot.
2062
2063U-Boot includes many features that so far have been part of some
2064special "boot loader" code within the Linux kernel. Also, any
2065"initrd" images to be used are no longer part of one big Linux image;
2066instead, kernel and "initrd" are separate images. This implementation
2067serves serveral purposes:
2068
2069- the same features can be used for other OS or standalone
2070 applications (for instance: using compressed images to reduce the
2071 Flash memory footprint)
2072
2073- it becomes much easier to port new Linux kernel versions because
2074 lots of low-level, hardware dependend stuff are done by U-Boot
2075
2076- the same Linux kernel image can now be used with different "initrd"
2077 images; of course this also means that different kernel images can
2078 be run with the same "initrd". This makes testing easier (you don't
2079 have to build a new "zImage.initrd" Linux image when you just
2080 change a file in your "initrd"). Also, a field-upgrade of the
2081 software is easier now.
2082
2083
2084Linux HOWTO:
2085============
2086
2087Porting Linux to U-Boot based systems:
2088---------------------------------------
2089
2090U-Boot cannot save you from doing all the necessary modifications to
2091configure the Linux device drivers for use with your target hardware
2092(no, we don't intend to provide a full virtual machine interface to
2093Linux :-).
2094
2095But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2096
2097Just make sure your machine specific header file (for instance
2098include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2099Information structure as we define in include/u-boot.h, and make
2100sure that your definition of IMAP_ADDR uses the same value as your
2101U-Boot configuration in CFG_IMMR.
2102
2103
2104Configuring the Linux kernel:
2105-----------------------------
2106
2107No specific requirements for U-Boot. Make sure you have some root
2108device (initial ramdisk, NFS) for your target system.
2109
2110
2111Building a Linux Image:
2112-----------------------
2113
wdenk24ee89b2002-11-03 17:56:27 +00002114With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2115not used. If you use recent kernel source, a new build target
2116"uImage" will exist which automatically builds an image usable by
2117U-Boot. Most older kernels also have support for a "pImage" target,
2118which was introduced for our predecessor project PPCBoot and uses a
2119100% compatible format.
wdenkc6097192002-11-03 00:24:07 +00002120
2121Example:
2122
2123 make TQM850L_config
2124 make oldconfig
2125 make dep
wdenk24ee89b2002-11-03 17:56:27 +00002126 make uImage
wdenkc6097192002-11-03 00:24:07 +00002127
wdenk24ee89b2002-11-03 17:56:27 +00002128The "uImage" build target uses a special tool (in 'tools/mkimage') to
2129encapsulate a compressed Linux kernel image with header information,
2130CRC32 checksum etc. for use with U-Boot. This is what we are doing:
wdenkc6097192002-11-03 00:24:07 +00002131
wdenk24ee89b2002-11-03 17:56:27 +00002132* build a standard "vmlinux" kernel image (in ELF binary format):
wdenkc6097192002-11-03 00:24:07 +00002133
wdenk24ee89b2002-11-03 17:56:27 +00002134* convert the kernel into a raw binary image:
2135
2136 ${CROSS_COMPILE}-objcopy -O binary \
2137 -R .note -R .comment \
2138 -S vmlinux linux.bin
2139
2140* compress the binary image:
2141
2142 gzip -9 linux.bin
2143
2144* package compressed binary image for U-Boot:
2145
2146 mkimage -A ppc -O linux -T kernel -C gzip \
2147 -a 0 -e 0 -n "Linux Kernel Image" \
2148 -d linux.bin.gz uImage
2149
2150
2151The "mkimage" tool can also be used to create ramdisk images for use
2152with U-Boot, either separated from the Linux kernel image, or
2153combined into one file. "mkimage" encapsulates the images with a 64
2154byte header containing information about target architecture,
2155operating system, image type, compression method, entry points, time
2156stamp, CRC32 checksums, etc.
2157
2158"mkimage" can be called in two ways: to verify existing images and
2159print the header information, or to build new images.
2160
2161In the first form (with "-l" option) mkimage lists the information
2162contained in the header of an existing U-Boot image; this includes
wdenkc6097192002-11-03 00:24:07 +00002163checksum verification:
2164
2165 tools/mkimage -l image
2166 -l ==> list image header information
2167
2168The second form (with "-d" option) is used to build a U-Boot image
2169from a "data file" which is used as image payload:
2170
2171 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2172 -n name -d data_file image
2173 -A ==> set architecture to 'arch'
2174 -O ==> set operating system to 'os'
2175 -T ==> set image type to 'type'
2176 -C ==> set compression type 'comp'
2177 -a ==> set load address to 'addr' (hex)
2178 -e ==> set entry point to 'ep' (hex)
2179 -n ==> set image name to 'name'
2180 -d ==> use image data from 'datafile'
2181
2182Right now, all Linux kernels use the same load address (0x00000000),
2183but the entry point address depends on the kernel version:
2184
2185- 2.2.x kernels have the entry point at 0x0000000C,
wdenk24ee89b2002-11-03 17:56:27 +00002186- 2.3.x and later kernels have the entry point at 0x00000000.
wdenkc6097192002-11-03 00:24:07 +00002187
2188So a typical call to build a U-Boot image would read:
2189
wdenk24ee89b2002-11-03 17:56:27 +00002190 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2191 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2192 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2193 > examples/uImage.TQM850L
2194 Image Name: 2.4.4 kernel for TQM850L
wdenkc6097192002-11-03 00:24:07 +00002195 Created: Wed Jul 19 02:34:59 2000
2196 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2197 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2198 Load Address: 0x00000000
wdenk24ee89b2002-11-03 17:56:27 +00002199 Entry Point: 0x00000000
wdenkc6097192002-11-03 00:24:07 +00002200
2201To verify the contents of the image (or check for corruption):
2202
wdenk24ee89b2002-11-03 17:56:27 +00002203 -> tools/mkimage -l examples/uImage.TQM850L
2204 Image Name: 2.4.4 kernel for TQM850L
wdenkc6097192002-11-03 00:24:07 +00002205 Created: Wed Jul 19 02:34:59 2000
2206 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2207 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2208 Load Address: 0x00000000
wdenk24ee89b2002-11-03 17:56:27 +00002209 Entry Point: 0x00000000
wdenkc6097192002-11-03 00:24:07 +00002210
2211NOTE: for embedded systems where boot time is critical you can trade
2212speed for memory and install an UNCOMPRESSED image instead: this
2213needs more space in Flash, but boots much faster since it does not
2214need to be uncompressed:
2215
wdenk24ee89b2002-11-03 17:56:27 +00002216 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2217 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2218 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2219 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2220 > examples/uImage.TQM850L-uncompressed
2221 Image Name: 2.4.4 kernel for TQM850L
wdenkc6097192002-11-03 00:24:07 +00002222 Created: Wed Jul 19 02:34:59 2000
2223 Image Type: PowerPC Linux Kernel Image (uncompressed)
2224 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2225 Load Address: 0x00000000
wdenk24ee89b2002-11-03 17:56:27 +00002226 Entry Point: 0x00000000
wdenkc6097192002-11-03 00:24:07 +00002227
2228
2229Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2230when your kernel is intended to use an initial ramdisk:
2231
2232 -> tools/mkimage -n 'Simple Ramdisk Image' \
2233 > -A ppc -O linux -T ramdisk -C gzip \
2234 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2235 Image Name: Simple Ramdisk Image
2236 Created: Wed Jan 12 14:01:50 2000
2237 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2238 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2239 Load Address: 0x00000000
2240 Entry Point: 0x00000000
2241
2242
2243Installing a Linux Image:
2244-------------------------
2245
2246To downloading a U-Boot image over the serial (console) interface,
2247you must convert the image to S-Record format:
2248
2249 objcopy -I binary -O srec examples/image examples/image.srec
2250
2251The 'objcopy' does not understand the information in the U-Boot
2252image header, so the resulting S-Record file will be relative to
2253address 0x00000000. To load it to a given address, you need to
2254specify the target address as 'offset' parameter with the 'loads'
2255command.
2256
2257Example: install the image to address 0x40100000 (which on the
2258TQM8xxL is in the first Flash bank):
2259
2260 => erase 40100000 401FFFFF
2261
2262 .......... done
2263 Erased 8 sectors
2264
2265 => loads 40100000
2266 ## Ready for S-Record download ...
2267 ~>examples/image.srec
2268 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2269 ...
2270 15989 15990 15991 15992
2271 [file transfer complete]
2272 [connected]
2273 ## Start Addr = 0x00000000
2274
2275
2276You can check the success of the download using the 'iminfo' command;
2277this includes a checksum verification so you can be sure no data
2278corruption happened:
2279
2280 => imi 40100000
2281
2282 ## Checking Image at 40100000 ...
2283 Image Name: 2.2.13 for initrd on TQM850L
2284 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2285 Data Size: 335725 Bytes = 327 kB = 0 MB
2286 Load Address: 00000000
2287 Entry Point: 0000000c
2288 Verifying Checksum ... OK
2289
2290
2291
2292Boot Linux:
2293-----------
2294
2295The "bootm" command is used to boot an application that is stored in
2296memory (RAM or Flash). In case of a Linux kernel image, the contents
2297of the "bootargs" environment variable is passed to the kernel as
2298parameters. You can check and modify this variable using the
2299"printenv" and "setenv" commands:
2300
2301
2302 => printenv bootargs
2303 bootargs=root=/dev/ram
2304
2305 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2306
2307 => printenv bootargs
2308 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2309
2310 => bootm 40020000
2311 ## Booting Linux kernel at 40020000 ...
2312 Image Name: 2.2.13 for NFS on TQM850L
2313 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2314 Data Size: 381681 Bytes = 372 kB = 0 MB
2315 Load Address: 00000000
2316 Entry Point: 0000000c
2317 Verifying Checksum ... OK
2318 Uncompressing Kernel Image ... OK
2319 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
2320 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2321 time_init: decrementer frequency = 187500000/60
2322 Calibrating delay loop... 49.77 BogoMIPS
2323 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2324 ...
2325
2326If you want to boot a Linux kernel with initial ram disk, you pass
2327the memory addreses of both the kernel and the initrd image (PPBCOOT
2328format!) to the "bootm" command:
2329
2330 => imi 40100000 40200000
2331
2332 ## Checking Image at 40100000 ...
2333 Image Name: 2.2.13 for initrd on TQM850L
2334 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2335 Data Size: 335725 Bytes = 327 kB = 0 MB
2336 Load Address: 00000000
2337 Entry Point: 0000000c
2338 Verifying Checksum ... OK
2339
2340 ## Checking Image at 40200000 ...
2341 Image Name: Simple Ramdisk Image
2342 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2343 Data Size: 566530 Bytes = 553 kB = 0 MB
2344 Load Address: 00000000
2345 Entry Point: 00000000
2346 Verifying Checksum ... OK
2347
2348 => bootm 40100000 40200000
2349 ## Booting Linux kernel at 40100000 ...
2350 Image Name: 2.2.13 for initrd on TQM850L
2351 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2352 Data Size: 335725 Bytes = 327 kB = 0 MB
2353 Load Address: 00000000
2354 Entry Point: 0000000c
2355 Verifying Checksum ... OK
2356 Uncompressing Kernel Image ... OK
2357 ## Loading RAMDisk Image at 40200000 ...
2358 Image Name: Simple Ramdisk Image
2359 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2360 Data Size: 566530 Bytes = 553 kB = 0 MB
2361 Load Address: 00000000
2362 Entry Point: 00000000
2363 Verifying Checksum ... OK
2364 Loading Ramdisk ... OK
2365 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
2366 Boot arguments: root=/dev/ram
2367 time_init: decrementer frequency = 187500000/60
2368 Calibrating delay loop... 49.77 BogoMIPS
2369 ...
2370 RAMDISK: Compressed image found at block 0
2371 VFS: Mounted root (ext2 filesystem).
2372
2373 bash#
2374
wdenk6069ff22003-02-28 00:49:47 +00002375More About U-Boot Image Types:
2376------------------------------
2377
2378U-Boot supports the following image types:
2379
2380 "Standalone Programs" are directly runnable in the environment
2381 provided by U-Boot; it is expected that (if they behave
2382 well) you can continue to work in U-Boot after return from
2383 the Standalone Program.
2384 "OS Kernel Images" are usually images of some Embedded OS which
2385 will take over control completely. Usually these programs
2386 will install their own set of exception handlers, device
2387 drivers, set up the MMU, etc. - this means, that you cannot
2388 expect to re-enter U-Boot except by resetting the CPU.
2389 "RAMDisk Images" are more or less just data blocks, and their
2390 parameters (address, size) are passed to an OS kernel that is
2391 being started.
2392 "Multi-File Images" contain several images, typically an OS
2393 (Linux) kernel image and one or more data images like
2394 RAMDisks. This construct is useful for instance when you want
2395 to boot over the network using BOOTP etc., where the boot
2396 server provides just a single image file, but you want to get
2397 for instance an OS kernel and a RAMDisk image.
stroesec1551ea2003-04-04 15:53:41 +00002398
wdenk6069ff22003-02-28 00:49:47 +00002399 "Multi-File Images" start with a list of image sizes, each
2400 image size (in bytes) specified by an "uint32_t" in network
2401 byte order. This list is terminated by an "(uint32_t)0".
2402 Immediately after the terminating 0 follow the images, one by
2403 one, all aligned on "uint32_t" boundaries (size rounded up to
2404 a multiple of 4 bytes).
stroesec1551ea2003-04-04 15:53:41 +00002405
wdenk6069ff22003-02-28 00:49:47 +00002406 "Firmware Images" are binary images containing firmware (like
2407 U-Boot or FPGA images) which usually will be programmed to
2408 flash memory.
stroesec1551ea2003-04-04 15:53:41 +00002409
wdenk6069ff22003-02-28 00:49:47 +00002410 "Script files" are command sequences that will be executed by
2411 U-Boot's command interpreter; this feature is especially
2412 useful when you configure U-Boot to use a real shell (hush)
2413 as command interpreter.
2414
wdenkc6097192002-11-03 00:24:07 +00002415
2416Standalone HOWTO:
2417=================
2418
2419One of the features of U-Boot is that you can dynamically load and
2420run "standalone" applications, which can use some resources of
2421U-Boot like console I/O functions or interrupt services.
2422
2423Two simple examples are included with the sources:
2424
2425"Hello World" Demo:
2426-------------------
2427
2428'examples/hello_world.c' contains a small "Hello World" Demo
2429application; it is automatically compiled when you build U-Boot.
2430It's configured to run at address 0x00040004, so you can play with it
2431like that:
2432
2433 => loads
2434 ## Ready for S-Record download ...
2435 ~>examples/hello_world.srec
2436 1 2 3 4 5 6 7 8 9 10 11 ...
2437 [file transfer complete]
2438 [connected]
2439 ## Start Addr = 0x00040004
2440
2441 => go 40004 Hello World! This is a test.
2442 ## Starting application at 0x00040004 ...
2443 Hello World
2444 argc = 7
2445 argv[0] = "40004"
2446 argv[1] = "Hello"
2447 argv[2] = "World!"
2448 argv[3] = "This"
2449 argv[4] = "is"
2450 argv[5] = "a"
2451 argv[6] = "test."
2452 argv[7] = "<NULL>"
2453 Hit any key to exit ...
2454
2455 ## Application terminated, rc = 0x0
2456
2457Another example, which demonstrates how to register a CPM interrupt
2458handler with the U-Boot code, can be found in 'examples/timer.c'.
2459Here, a CPM timer is set up to generate an interrupt every second.
2460The interrupt service routine is trivial, just printing a '.'
2461character, but this is just a demo program. The application can be
2462controlled by the following keys:
2463
2464 ? - print current values og the CPM Timer registers
2465 b - enable interrupts and start timer
2466 e - stop timer and disable interrupts
2467 q - quit application
2468
2469 => loads
2470 ## Ready for S-Record download ...
2471 ~>examples/timer.srec
2472 1 2 3 4 5 6 7 8 9 10 11 ...
2473 [file transfer complete]
2474 [connected]
2475 ## Start Addr = 0x00040004
2476
2477 => go 40004
2478 ## Starting application at 0x00040004 ...
2479 TIMERS=0xfff00980
2480 Using timer 1
2481 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2482
2483Hit 'b':
2484 [q, b, e, ?] Set interval 1000000 us
2485 Enabling timer
2486Hit '?':
2487 [q, b, e, ?] ........
2488 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2489Hit '?':
2490 [q, b, e, ?] .
2491 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2492Hit '?':
2493 [q, b, e, ?] .
2494 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2495Hit '?':
2496 [q, b, e, ?] .
2497 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2498Hit 'e':
2499 [q, b, e, ?] ...Stopping timer
2500Hit 'q':
2501 [q, b, e, ?] ## Application terminated, rc = 0x0
2502
2503
wdenk85ec0bc2003-03-31 16:34:49 +00002504
2505Minicom warning:
2506================
2507
2508Over time, many people have reported problems when trying to used the
2509"minicom" terminal emulation program for serial download. I (wd)
2510consider minicom to be broken, and recommend not to use it. Under
2511Unix, I recommend to use CKermit for general purpose use (and
2512especially for kermit binary protocol download ("loadb" command), and
2513use "cu" for S-Record download ("loads" command).
2514
wdenkc6097192002-11-03 00:24:07 +00002515NetBSD Notes:
2516=============
2517
2518Starting at version 0.9.2, U-Boot supports NetBSD both as host
2519(build U-Boot) and target system (boots NetBSD/mpc8xx).
2520
2521Building requires a cross environment; it is known to work on
2522NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2523need gmake since the Makefiles are not compatible with BSD make).
2524Note that the cross-powerpc package does not install include files;
2525attempting to build U-Boot will fail because <machine/ansi.h> is
2526missing. This file has to be installed and patched manually:
2527
2528 # cd /usr/pkg/cross/powerpc-netbsd/include
2529 # mkdir powerpc
2530 # ln -s powerpc machine
2531 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2532 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2533
2534Native builds *don't* work due to incompatibilities between native
2535and U-Boot include files.
2536
2537Booting assumes that (the first part of) the image booted is a
2538stage-2 loader which in turn loads and then invokes the kernel
2539proper. Loader sources will eventually appear in the NetBSD source
2540tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2541meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2542details.
2543
2544
2545Implementation Internals:
2546=========================
2547
2548The following is not intended to be a complete description of every
2549implementation detail. However, it should help to understand the
2550inner workings of U-Boot and make it easier to port it to custom
2551hardware.
2552
2553
2554Initial Stack, Global Data:
2555---------------------------
2556
2557The implementation of U-Boot is complicated by the fact that U-Boot
2558starts running out of ROM (flash memory), usually without access to
2559system RAM (because the memory controller is not initialized yet).
2560This means that we don't have writable Data or BSS segments, and BSS
2561is not initialized as zero. To be able to get a C environment working
2562at all, we have to allocate at least a minimal stack. Implementation
2563options for this are defined and restricted by the CPU used: Some CPU
2564models provide on-chip memory (like the IMMR area on MPC8xx and
2565MPC826x processors), on others (parts of) the data cache can be
2566locked as (mis-) used as memory, etc.
2567
wdenk43d96162003-03-06 00:02:04 +00002568 Chris Hallinan posted a good summy of these issues to the
2569 u-boot-users mailing list:
2570
2571 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2572 From: "Chris Hallinan" <clh@net1plus.com>
2573 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2574 ...
2575
2576 Correct me if I'm wrong, folks, but the way I understand it
2577 is this: Using DCACHE as initial RAM for Stack, etc, does not
2578 require any physical RAM backing up the cache. The cleverness
2579 is that the cache is being used as a temporary supply of
2580 necessary storage before the SDRAM controller is setup. It's
2581 beyond the scope of this list to expain the details, but you
2582 can see how this works by studying the cache architecture and
2583 operation in the architecture and processor-specific manuals.
2584
2585 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2586 is another option for the system designer to use as an
2587 initial stack/ram area prior to SDRAM being available. Either
2588 option should work for you. Using CS 4 should be fine if your
2589 board designers haven't used it for something that would
2590 cause you grief during the initial boot! It is frequently not
2591 used.
2592
2593 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2594 with your processor/board/system design. The default value
2595 you will find in any recent u-boot distribution in
2596 Walnut405.h should work for you. I'd set it to a value larger
2597 than your SDRAM module. If you have a 64MB SDRAM module, set
2598 it above 400_0000. Just make sure your board has no resources
2599 that are supposed to respond to that address! That code in
2600 start.S has been around a while and should work as is when
2601 you get the config right.
2602
2603 -Chris Hallinan
2604 DS4.COM, Inc.
2605
wdenkc6097192002-11-03 00:24:07 +00002606It is essential to remember this, since it has some impact on the C
2607code for the initialization procedures:
2608
2609* Initialized global data (data segment) is read-only. Do not attempt
2610 to write it.
2611
2612* Do not use any unitialized global data (or implicitely initialized
2613 as zero data - BSS segment) at all - this is undefined, initiali-
2614 zation is performed later (when relocationg to RAM).
2615
2616* Stack space is very limited. Avoid big data buffers or things like
2617 that.
2618
2619Having only the stack as writable memory limits means we cannot use
2620normal global data to share information beween the code. But it
2621turned out that the implementation of U-Boot can be greatly
2622simplified by making a global data structure (gd_t) available to all
2623functions. We could pass a pointer to this data as argument to _all_
2624functions, but this would bloat the code. Instead we use a feature of
2625the GCC compiler (Global Register Variables) to share the data: we
2626place a pointer (gd) to the global data into a register which we
2627reserve for this purpose.
2628
2629When chosing a register for such a purpose we are restricted by the
2630relevant (E)ABI specifications for the current architecture, and by
2631GCC's implementation.
2632
2633For PowerPC, the following registers have specific use:
2634 R1: stack pointer
2635 R2: TOC pointer
2636 R3-R4: parameter passing and return values
2637 R5-R10: parameter passing
2638 R13: small data area pointer
2639 R30: GOT pointer
2640 R31: frame pointer
2641
2642 (U-Boot also uses R14 as internal GOT pointer.)
2643
2644 ==> U-Boot will use R29 to hold a pointer to the global data
2645
2646 Note: on PPC, we could use a static initializer (since the
2647 address of the global data structure is known at compile time),
2648 but it turned out that reserving a register results in somewhat
2649 smaller code - although the code savings are not that big (on
2650 average for all boards 752 bytes for the whole U-Boot image,
2651 624 text + 127 data).
2652
2653On ARM, the following registers are used:
2654
2655 R0: function argument word/integer result
2656 R1-R3: function argument word
2657 R9: GOT pointer
2658 R10: stack limit (used only if stack checking if enabled)
2659 R11: argument (frame) pointer
2660 R12: temporary workspace
2661 R13: stack pointer
2662 R14: link register
2663 R15: program counter
2664
2665 ==> U-Boot will use R8 to hold a pointer to the global data
2666
2667
2668
2669Memory Management:
2670------------------
2671
2672U-Boot runs in system state and uses physical addresses, i.e. the
2673MMU is not used either for address mapping nor for memory protection.
2674
2675The available memory is mapped to fixed addresses using the memory
2676controller. In this process, a contiguous block is formed for each
2677memory type (Flash, SDRAM, SRAM), even when it consists of several
2678physical memory banks.
2679
2680U-Boot is installed in the first 128 kB of the first Flash bank (on
2681TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2682booting and sizing and initializing DRAM, the code relocates itself
2683to the upper end of DRAM. Immediately below the U-Boot code some
2684memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2685configuration setting]. Below that, a structure with global Board
2686Info data is placed, followed by the stack (growing downward).
2687
2688Additionally, some exception handler code is copied to the low 8 kB
2689of DRAM (0x00000000 ... 0x00001FFF).
2690
2691So a typical memory configuration with 16 MB of DRAM could look like
2692this:
2693
2694 0x0000 0000 Exception Vector code
2695 :
2696 0x0000 1FFF
2697 0x0000 2000 Free for Application Use
2698 :
2699 :
2700
2701 :
2702 :
2703 0x00FB FF20 Monitor Stack (Growing downward)
2704 0x00FB FFAC Board Info Data and permanent copy of global data
2705 0x00FC 0000 Malloc Arena
2706 :
2707 0x00FD FFFF
2708 0x00FE 0000 RAM Copy of Monitor Code
2709 ... eventually: LCD or video framebuffer
2710 ... eventually: pRAM (Protected RAM - unchanged by reset)
2711 0x00FF FFFF [End of RAM]
2712
2713
2714System Initialization:
2715----------------------
2716
2717In the reset configuration, U-Boot starts at the reset entry point
2718(on most PowerPC systens at address 0x00000100). Because of the reset
2719configuration for CS0# this is a mirror of the onboard Flash memory.
2720To be able to re-map memory U-Boot then jumps to it's link address.
2721To be able to implement the initialization code in C, a (small!)
2722initial stack is set up in the internal Dual Ported RAM (in case CPUs
2723which provide such a feature like MPC8xx or MPC8260), or in a locked
2724part of the data cache. After that, U-Boot initializes the CPU core,
2725the caches and the SIU.
2726
2727Next, all (potentially) available memory banks are mapped using a
2728preliminary mapping. For example, we put them on 512 MB boundaries
2729(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2730on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2731programmed for SDRAM access. Using the temporary configuration, a
2732simple memory test is run that determines the size of the SDRAM
2733banks.
2734
2735When there is more than one SDRAM bank, and the banks are of
2736different size, the larger is mapped first. For equal size, the first
2737bank (CS2#) is mapped first. The first mapping is always for address
27380x00000000, with any additional banks following immediately to create
2739contiguous memory starting from 0.
2740
2741Then, the monitor installs itself at the upper end of the SDRAM area
2742and allocates memory for use by malloc() and for the global Board
2743Info data; also, the exception vector code is copied to the low RAM
2744pages, and the final stack is set up.
2745
2746Only after this relocation will you have a "normal" C environment;
2747until that you are restricted in several ways, mostly because you are
2748running from ROM, and because the code will have to be relocated to a
2749new address in RAM.
2750
2751
2752U-Boot Porting Guide:
2753----------------------
2754
2755[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
wdenk6aff3112002-12-17 01:51:00 +00002756list, October 2002]
wdenkc6097192002-11-03 00:24:07 +00002757
2758
2759int main (int argc, char *argv[])
2760{
2761 sighandler_t no_more_time;
2762
2763 signal (SIGALRM, no_more_time);
2764 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2765
2766 if (available_money > available_manpower) {
2767 pay consultant to port U-Boot;
2768 return 0;
2769 }
2770
2771 Download latest U-Boot source;
2772
wdenk6aff3112002-12-17 01:51:00 +00002773 Subscribe to u-boot-users mailing list;
2774
wdenkc6097192002-11-03 00:24:07 +00002775 if (clueless) {
2776 email ("Hi, I am new to U-Boot, how do I get started?");
2777 }
2778
2779 while (learning) {
2780 Read the README file in the top level directory;
2781 Read http://www.denx.de/re/DPLG.html
2782 Read the source, Luke;
2783 }
2784
2785 if (available_money > toLocalCurrency ($2500)) {
2786 Buy a BDI2000;
2787 } else {
2788 Add a lot of aggravation and time;
2789 }
2790
2791 Create your own board support subdirectory;
2792
wdenk6aff3112002-12-17 01:51:00 +00002793 Create your own board config file;
2794
wdenkc6097192002-11-03 00:24:07 +00002795 while (!running) {
2796 do {
2797 Add / modify source code;
2798 } until (compiles);
2799 Debug;
2800 if (clueless)
2801 email ("Hi, I am having problems...");
2802 }
2803 Send patch file to Wolfgang;
2804
2805 return 0;
2806}
2807
2808void no_more_time (int sig)
2809{
2810 hire_a_guru();
2811}
2812
2813
2814
2815Coding Standards:
2816-----------------
2817
2818All contributions to U-Boot should conform to the Linux kernel
2819coding style; see the file "Documentation/CodingStyle" in your Linux
2820kernel source directory.
2821
2822Please note that U-Boot is implemented in C (and to some small parts
2823in Assembler); no C++ is used, so please do not use C++ style
2824comments (//) in your code.
2825
2826Submissions which do not conform to the standards may be returned
2827with a request to reformat the changes.
2828
2829
2830Submitting Patches:
2831-------------------
2832
2833Since the number of patches for U-Boot is growing, we need to
2834establish some rules. Submissions which do not conform to these rules
2835may be rejected, even when they contain important and valuable stuff.
2836
2837
2838When you send a patch, please include the following information with
2839it:
2840
2841* For bug fixes: a description of the bug and how your patch fixes
2842 this bug. Please try to include a way of demonstrating that the
2843 patch actually fixes something.
2844
2845* For new features: a description of the feature and your
2846 implementation.
2847
2848* A CHANGELOG entry as plaintext (separate from the patch)
2849
2850* For major contributions, your entry to the CREDITS file
2851
2852* When you add support for a new board, don't forget to add this
2853 board to the MAKEALL script, too.
2854
2855* If your patch adds new configuration options, don't forget to
2856 document these in the README file.
2857
2858* The patch itself. If you are accessing the CVS repository use "cvs
2859 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
2860 version of diff does not support these options, then get the latest
2861 version of GNU diff.
2862
2863 We accept patches as plain text, MIME attachments or as uuencoded
2864 gzipped text.
2865
2866Notes:
2867
2868* Before sending the patch, run the MAKEALL script on your patched
2869 source tree and make sure that no errors or warnings are reported
2870 for any of the boards.
2871
2872* Keep your modifications to the necessary minimum: A patch
2873 containing several unrelated changes or arbitrary reformats will be
2874 returned with a request to re-formatting / split it.
2875
2876* If you modify existing code, make sure that your new code does not
2877 add to the memory footprint of the code ;-) Small is beautiful!
2878 When adding new features, these should compile conditionally only
2879 (using #ifdef), and the resulting code with the new feature
2880 disabled must not need more memory than the old code without your
2881 modification.