2 # (C) Copyright 2000 - 2002
3 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
5 # See file CREDITS for list of people who contributed to this
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.
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.
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,
27 This directory contains the source code for U-Boot, a boot loader for
28 Embedded boards based on PowerPC and ARM processors, which can be
29 installed in a boot ROM and used to initialize and test the hardware
30 or to download and run application code.
32 The development of U-Boot is closely related to Linux: some parts of
33 the source code originate in the Linux source tree, we have some
34 header files in common, and special provision has been made to
35 support booting of Linux images.
37 Some attention has been paid to make this software easily
38 configurable and extendable. For instance, all monitor commands are
39 implemented with the same call interface, so that it's very easy to
40 add new commands. Also, instead of permanently adding rarely used
41 code (for instance hardware test utilities) to the monitor, you can
42 load and run it dynamically.
48 In general, all boards for which a configuration option exists in the
49 Makefile have been tested to some extent and can be considered
50 "working". In fact, many of them are used in production systems.
52 In case of problems see the CHANGELOG and CREDITS files to find out
53 who contributed the specific port.
59 In case you have questions about, problems with or contributions for
60 U-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
62 previous traffic on the mailing list - please search the archive
63 before asking FAQ's. Please see
64 http://lists.sourceforge.net/lists/listinfo/u-boot-users/
70 - start from 8xxrom sources
71 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
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
79 * PCMCIA / CompactFLash / ATA disk / SCSI ... boot
80 - create ARMBoot project (http://sourceforge.net/projects/armboot)
81 - add other CPU families (starting with ARM)
82 - create U-Boot project (http://sourceforge.net/projects/u-boot)
88 The "official" name of this project is "Das U-Boot". The spelling
89 "U-Boot" shall be used in all written text (documentation, comments
90 in source files etc.). Example:
92 This is the README file for the U-Boot project.
94 File names etc. shall be based on the string "u-boot". Examples:
96 include/asm-ppc/u-boot.h
98 #include <asm/u-boot.h>
100 Variable names, preprocessor constants etc. shall be either based on
101 the string "u_boot" or on "U_BOOT". Example:
103 U_BOOT_VERSION u_boot_logo
104 IH_OS_U_BOOT u_boot_hush_start
110 U-Boot uses a 3 level version number containing a version, a
111 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
112 sub-version "34", and patchlevel "4".
114 The patchlevel is used to indicate certain stages of development
115 between released versions, i. e. officially released versions of
116 U-Boot will always have a patchlevel of "0".
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.
142 - cpu/74xx_7xx Files specific to Motorola MPC74xx and 7xx CPUs
143 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
144 - 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
149 - board/LEOX/ Files specific to boards manufactured by The LEOX team
150 - board/LEOX/elpt860 Files specific to ELPT860 boards
152 Files specific to RPXClassic boards
153 - board/RPXlite Files specific to RPXlite boards
154 - board/c2mon Files specific to c2mon boards
155 - board/cmi Files specific to cmi boards
156 - 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
177 Files specific to ESTEEM192E boards
178 - board/etx094 Files specific to ETX_094 boards
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 and GEN860T_SC 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
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
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
209 Files specific to PPMC8260 boards
211 Files specific to RPXsuper boards
213 Files specific to RSDproto boards
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
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
234 Software Configuration:
235 =======================
237 Configuration is usually done using C preprocessor defines; the
238 rationale behind that is to avoid dead code whenever possible.
240 There are two classes of configuration variables:
242 * Configuration _OPTIONS_:
243 These are selectable by the user and have names beginning with
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
251 Later we will add a configuration tool - probably similar to or even
252 identical to what's used for the Linux kernel. Right now, we have to
253 do the configuration by hand, which means creating some symbolic
254 links and editing some configuration files. We use the TQM8xxL boards
258 Selection of Processor Architecture and Board Type:
259 ---------------------------------------------------
261 For all supported boards there are ready-to-use default
262 configurations available; just type "make <board_name>_config".
264 Example: For a TQM823L module type:
269 For the Cogent platform, you need to specify the cpu type as well;
270 e.g. "make cogent_mpc8xx_config". And also configure the cogent
271 directory according to the instructions in cogent/README.
274 Configuration Options:
275 ----------------------
277 Configuration depends on the combination of board and CPU type; all
278 such information is kept in a configuration file
279 "include/configs/<board_name>.h".
281 Example: For a TQM823L module, all configuration settings are in
282 "include/configs/TQM823L.h".
285 Many of the options are named exactly as the corresponding Linux
286 kernel configuration options. The intention is to make it easier to
287 build a config tool - later.
290 The following options need to be configured:
292 - CPU Type: Define exactly one of
296 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
298 or CONFIG_MPC824X, CONFIG_MPC8260
311 - Board Type: Define exactly one of
313 PowerPC based boards:
314 ---------------------
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,
345 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
346 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
352 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
353 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
354 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
358 - CPU Module Type: (if CONFIG_COGENT is defined)
359 Define exactly one of
361 --- FIXME --- not tested yet:
362 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
363 CONFIG_CMA287_23, CONFIG_CMA287_50
365 - Motherboard Type: (if CONFIG_COGENT is defined)
366 Define exactly one of
367 CONFIG_CMA101, CONFIG_CMA102
369 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
370 Define one or more of
373 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
374 Define one or more of
375 CONFIG_LCD_HEARTBEAT - update a character position on
376 the lcd display every second with
379 - MPC824X Family Member (if CONFIG_MPC824X is defined)
380 Define exactly one of
381 CONFIG_MPC8240, CONFIG_MPC8245
383 - 8xx CPU Options: (if using an 8xx cpu)
384 Define one or more of
385 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
386 no 32KHz reference PIT/RTC clock
391 U-Boot stores all clock information in Hz
392 internally. For binary compatibility with older Linux
393 kernels (which expect the clocks passed in the
394 bd_info data to be in MHz) the environment variable
395 "clocks_in_mhz" can be defined so that U-Boot
396 converts clock data to MHZ before passing it to the
399 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
400 "clocks_in_mhz=1" is automatically included in the
404 Depending on board, define exactly one serial port
405 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
406 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
407 console by defining CONFIG_8xx_CONS_NONE
409 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
410 port routines must be defined elsewhere
411 (i.e. serial_init(), serial_getc(), ...)
414 Enables console device for a color framebuffer. Needs following
415 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
416 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
418 VIDEO_HW_RECTFILL graphic chip supports
421 VIDEO_HW_BITBLT graphic chip supports
422 bit-blit (cf. smiLynxEM)
423 VIDEO_VISIBLE_COLS visible pixel columns
425 VIDEO_VISIBLE_ROWS visible pixel rows
426 VIDEO_PIXEL_SIZE bytes per pixel
427 VIDEO_DATA_FORMAT graphic data format
428 (0-5, cf. cfb_console.c)
429 VIDEO_FB_ADRS framebuffer address
430 VIDEO_KBD_INIT_FCT keyboard int fct
431 (i.e. i8042_kbd_init())
432 VIDEO_TSTC_FCT test char fct
434 VIDEO_GETC_FCT get char fct
436 CONFIG_CONSOLE_CURSOR cursor drawing on/off
437 (requires blink timer
439 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
440 CONFIG_CONSOLE_TIME display time/date info in
442 (requires CFG_CMD_DATE)
443 CONFIG_VIDEO_LOGO display Linux logo in
445 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
446 linux_logo.h for logo.
447 Requires CONFIG_VIDEO_LOGO
448 CONFIG_CONSOLE_EXTRA_INFO
449 addional board info beside
452 When CONFIG_CFB_CONSOLE is defined, video console is
453 default i/o. Serial console can be forced with
454 environment 'console=serial'.
457 CONFIG_BAUDRATE - in bps
458 Select one of the baudrates listed in
459 CFG_BAUDRATE_TABLE, see below.
461 - Interrupt driven serial port input:
462 CONFIG_SERIAL_SOFTWARE_FIFO
465 Use an interrupt handler for receiving data on the
466 serial port. It also enables using hardware handshake
467 (RTS/CTS) and UART's built-in FIFO. Set the number of
468 bytes the interrupt driven input buffer should have.
470 Set to 0 to disable this feature (this is the default).
471 This will also disable hardware handshake.
473 - Console UART Number:
477 If defined internal UART1 (and not UART0) is used
478 as default U-Boot console.
480 - Boot Delay: CONFIG_BOOTDELAY - in seconds
481 Delay before automatically booting the default image;
482 set to -1 to disable autoboot.
484 See doc/README.autoboot for these options that
485 work with CONFIG_BOOTDELAY. None are required.
486 CONFIG_BOOT_RETRY_TIME
487 CONFIG_BOOT_RETRY_MIN
488 CONFIG_AUTOBOOT_KEYED
489 CONFIG_AUTOBOOT_PROMPT
490 CONFIG_AUTOBOOT_DELAY_STR
491 CONFIG_AUTOBOOT_STOP_STR
492 CONFIG_AUTOBOOT_DELAY_STR2
493 CONFIG_AUTOBOOT_STOP_STR2
494 CONFIG_ZERO_BOOTDELAY_CHECK
495 CONFIG_RESET_TO_RETRY
499 Only needed when CONFIG_BOOTDELAY is enabled;
500 define a command string that is automatically executed
501 when no character is read on the console interface
502 within "Boot Delay" after reset.
505 This can be used to pass arguments to the bootm
506 command. The value of CONFIG_BOOTARGS goes into the
507 environment value "bootargs".
509 CONFIG_RAMBOOT and CONFIG_NFSBOOT
510 The value of these goes into the environment as
511 "ramboot" and "nfsboot" respectively, and can be used
512 as a convenience, when switching between booting from
518 When this option is #defined, the existence of the
519 environment variable "preboot" will be checked
520 immediately before starting the CONFIG_BOOTDELAY
521 countdown and/or running the auto-boot command resp.
522 entering interactive mode.
524 This feature is especially useful when "preboot" is
525 automatically generated or modified. For an example
526 see the LWMON board specific code: here "preboot" is
527 modified when the user holds down a certain
528 combination of keys on the (special) keyboard when
531 - Serial Download Echo Mode:
533 If defined to 1, all characters received during a
534 serial download (using the "loads" command) are
535 echoed back. This might be needed by some terminal
536 emulations (like "cu"), but may as well just take
537 time on others. This setting #define's the initial
538 value of the "loads_echo" environment variable.
540 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
542 Select one of the baudrates listed in
543 CFG_BAUDRATE_TABLE, see below.
547 Most monitor functions can be selected (or
548 de-selected) by adjusting the definition of
549 CONFIG_COMMANDS; to select individual functions,
550 #define CONFIG_COMMANDS by "OR"ing any of the
553 #define enables commands:
554 -------------------------
555 CFG_CMD_ASKENV * ask for env variable
557 CFG_CMD_BEDBUG Include BedBug Debugger
559 CFG_CMD_CACHE icache, dcache
560 CFG_CMD_CONSOLE coninfo
561 CFG_CMD_DATE * support for RTC, date/time...
562 CFG_CMD_DHCP DHCP support
563 CFG_CMD_ECHO * echo arguments
564 CFG_CMD_EEPROM * EEPROM read/write support
565 CFG_CMD_ELF bootelf, bootvx
567 CFG_CMD_FDC * Floppy Disk Support
568 CFG_CMD_FDOS * Dos diskette Support
569 CFG_CMD_FLASH flinfo, erase, protect
570 CFG_CMD_FPGA FPGA device initialization support
571 CFG_CMD_I2C * I2C serial bus support
572 CFG_CMD_IDE * IDE harddisk support
574 CFG_CMD_IMMAP * IMMR dump support
575 CFG_CMD_IRQ * irqinfo
579 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
581 CFG_CMD_MII MII utility commands
582 CFG_CMD_NET bootp, tftpboot, rarpboot
583 CFG_CMD_PCI * pciinfo
584 CFG_CMD_PCMCIA * PCMCIA support
585 CFG_CMD_REGINFO * Register dump
586 CFG_CMD_RUN run command in env variable
587 CFG_CMD_SCSI * SCSI Support
588 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
589 CFG_CMD_SPI * SPI serial bus support
590 CFG_CMD_USB * USB support
591 CFG_CMD_BSP * Board SPecific functions
592 -----------------------------------------------
595 CFG_CMD_DFL Default configuration; at the moment
596 this is includes all commands, except
597 the ones marked with "*" in the list
600 If you don't define CONFIG_COMMANDS it defaults to
601 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
602 override the default settings in the respective
605 EXAMPLE: If you want all functions except of network
606 support you can write:
608 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
611 Note: Don't enable the "icache" and "dcache" commands
612 (configuration option CFG_CMD_CACHE) unless you know
613 what you (and your U-Boot users) are doing. Data
614 cache cannot be enabled on systems like the 8xx or
615 8260 (where accesses to the IMMR region must be
616 uncached), and it cannot be disabled on all other
617 systems where we (mis-) use the data cache to hold an
618 initial stack and some data.
621 XXX - this list needs to get updated!
625 If this variable is defined, it enables watchdog
626 support. There must support in the platform specific
627 code for a watchdog. For the 8xx and 8260 CPUs, the
628 SIU Watchdog feature is enabled in the SYPCR
632 CONFIG_VERSION_VARIABLE
633 If this variable is defined, an environment variable
634 named "ver" is created by U-Boot showing the U-Boot
635 version as printed by the "version" command.
636 This variable is readonly.
640 When CFG_CMD_DATE is selected, the type of the RTC
641 has to be selected, too. Define exactly one of the
644 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
645 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
646 CONFIG_RTC_MC146818 - use MC146818 RTC
647 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
648 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
649 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
650 CONFIG_RTC_DS164x - use Dallas DS164x RTC
654 When CONFIG_TIMESTAMP is selected, the timestamp
655 (date and time) of an image is printed by image
656 commands like bootm or iminfo. This option is
657 automatically enabled when you select CFG_CMD_DATE .
660 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
661 and/or CONFIG_ISO_PARTITION
663 If IDE or SCSI support is enabled (CFG_CMD_IDE or
664 CFG_CMD_SCSI) you must configure support for at least
665 one partition type as well.
668 CONFIG_IDE_RESET_ROUTINE
670 Set this to define that instead of a reset Pin, the
671 routine ide_set_reset(int idereset) will be used.
676 Set this to enable ATAPI support.
679 At the moment only there is only support for the
680 SYM53C8XX SCSI controller; define
681 CONFIG_SCSI_SYM53C8XX to enable it.
683 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
684 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
685 CFG_SCSI_MAX_LUN] can be adjusted to define the
686 maximum numbers of LUNs, SCSI ID's and target
688 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
690 - NETWORK Support (PCI):
692 Support for Intel 82557/82559/82559ER chips.
693 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
694 write routine for first time initialisation.
697 Support for Digital 2114x chips.
698 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
699 modem chip initialisation (KS8761/QS6611).
702 Support for National dp83815 chips.
705 Support for National dp8382[01] gigabit chips.
707 - NETWORK Support (other):
709 CONFIG_DRIVER_LAN91C96
710 Support for SMSC's LAN91C96 chips.
713 Define this to hold the physical address
714 of the LAN91C96's I/O space
716 CONFIG_LAN91C96_USE_32_BIT
717 Define this to enable 32 bit addressing
720 At the moment only the UHCI host controller is
721 supported (PIP405, MIP405); define
722 CONFIG_USB_UHCI to enable it.
723 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
724 end define CONFIG_USB_STORAGE to enable the USB
727 Supported are USB Keyboards and USB Floppy drives
733 Define this to enable standard (PC-Style) keyboard
737 Standard PC keyboard driver with US (is default) and
738 GERMAN key layout (switch via environment 'keymap=de') support.
739 Export function i8042_kbd_init, i8042_tstc and i8042_getc
740 for cfb_console. Supports cursor blinking.
745 Define this to enable video support (for output to
750 Enable Chips & Technologies 69000 Video chip
752 CONFIG_VIDEO_SMI_LYNXEM
753 Enable Silicon Motion SMI 712/710/810 Video chip
754 Videomode are selected via environment 'videomode' with
755 standard LiLo mode numbers.
756 Following modes are supported (* is default):
758 800x600 1024x768 1280x1024
759 256 (8bit) 303* 305 307
760 65536 (16bit) 314 317 31a
761 16,7 Mill (24bit) 315 318 31b
762 (i.e. setenv videomode 317; saveenv; reset;)
764 CONFIG_VIDEO_SED13806
765 Enable Epson SED13806 driver. This driver supports 8bpp
766 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
767 or CONFIG_VIDEO_SED13806_16BPP
770 - LCD Support: CONFIG_LCD
772 Define this to enable LCD support (for output to LCD
773 display); also select one of the supported displays
774 by defining one of these:
776 CONFIG_NEC_NL6648AC33:
778 NEC NL6648AC33-18. Active, color, single scan.
780 CONFIG_NEC_NL6648BC20
782 NEC NL6648BC20-08. 6.5", 640x480.
783 Active, color, single scan.
787 Sharp 320x240. Active, color, single scan.
788 It isn't 16x9, and I am not sure what it is.
790 CONFIG_SHARP_LQ64D341
792 Sharp LQ64D341 display, 640x480.
793 Active, color, single scan.
797 HLD1045 display, 640x480.
798 Active, color, single scan.
802 Optrex CBL50840-2 NF-FW 99 22 M5
804 Hitachi LMG6912RPFC-00T
808 320x240. Black & white.
810 Normally display is black on white background; define
811 CFG_WHITE_ON_BLACK to get it inverted.
813 - Spash Screen Support: CONFIG_SPLASH_SCREEN
815 If this option is set, the environment is checked for
816 a variable "splashimage". If found, the usual display
817 of logo, copyright and system information on the LCD
818 is supressed and the BMP image at the address
819 specified in "splashimage" is loaded instead. The
820 console is redirected to the "nulldev", too. This
821 allows for a "silent" boot where a splash screen is
822 loaded very quickly after power-on.
830 Define a default value for ethernet address to use
831 for the respective ethernet interface, in case this
832 is not determined automatically.
837 Define a default value for the IP address to use for
838 the default ethernet interface, in case this is not
839 determined through e.g. bootp.
844 Defines a default value for theIP address of a TFTP
845 server to contact when using the "tftboot" command.
847 - BOOTP Recovery Mode:
848 CONFIG_BOOTP_RANDOM_DELAY
850 If you have many targets in a network that try to
851 boot using BOOTP, you may want to avoid that all
852 systems send out BOOTP requests at precisely the same
853 moment (which would happen for instance at recovery
854 from a power failure, when all systems will try to
855 boot, thus flooding the BOOTP server. Defining
856 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
857 inserted before sending out BOOTP requests. The
858 following delays are insterted then:
860 1st BOOTP request: delay 0 ... 1 sec
861 2nd BOOTP request: delay 0 ... 2 sec
862 3rd BOOTP request: delay 0 ... 4 sec
864 BOOTP requests: delay 0 ... 8 sec
866 - Status LED: CONFIG_STATUS_LED
868 Several configurations allow to display the current
869 status using a LED. For instance, the LED will blink
870 fast while running U-Boot code, stop blinking as
871 soon as a reply to a BOOTP request was received, and
872 start blinking slow once the Linux kernel is running
873 (supported by a status LED driver in the Linux
874 kernel). Defining CONFIG_STATUS_LED enables this
877 - CAN Support: CONFIG_CAN_DRIVER
879 Defining CONFIG_CAN_DRIVER enables CAN driver support
880 on those systems that support this (optional)
881 feature, like the TQM8xxL modules.
883 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
885 Enables I2C serial bus commands. If this is selected,
886 either CONFIG_HARD_I2C or CONFIG_SOFT_I2C must be defined
887 to include the appropriate I2C driver.
889 See also: common/cmd_i2c.c for a description of the
890 command line interface.
895 Selects the CPM hardware driver for I2C.
899 Use software (aka bit-banging) driver instead of CPM
900 or similar hardware support for I2C. This is configured
901 via the following defines.
905 (Optional). Any commands necessary to enable I2C
906 controller or configure ports.
910 (Only for MPC8260 CPU). The I/O port to use (the code
911 assumes both bits are on the same port). Valid values
912 are 0..3 for ports A..D.
916 The code necessary to make the I2C data line active
917 (driven). If the data line is open collector, this
922 The code necessary to make the I2C data line tri-stated
923 (inactive). If the data line is open collector, this
928 Code that returns TRUE if the I2C data line is high,
933 If <bit> is TRUE, sets the I2C data line high. If it
934 is FALSE, it clears it (low).
938 If <bit> is TRUE, sets the I2C clock line high. If it
939 is FALSE, it clears it (low).
943 This delay is invoked four times per clock cycle so this
944 controls the rate of data transfer. The data rate thus
945 is 1 / (I2C_DELAY * 4).
949 When a board is reset during an i2c bus transfer
950 chips might think that the current transfer is still
951 in progress. On some boards it is possible to access
952 the i2c SCLK line directly, either by using the
953 processor pin as a GPIO or by having a second pin
954 connected to the bus. If this option is defined a
955 custom i2c_init_board() routine in boards/xxx/board.c
956 is run early in the boot sequence.
958 - SPI Support: CONFIG_SPI
960 Enables SPI driver (so far only tested with
961 SPI EEPROM, also an instance works with Crystal A/D and
962 D/As on the SACSng board)
966 Enables extended (16-bit) SPI EEPROM addressing.
967 (symmetrical to CONFIG_I2C_X)
971 Enables a software (bit-bang) SPI driver rather than
972 using hardware support. This is a general purpose
973 driver that only requires three general I/O port pins
974 (two outputs, one input) to function. If this is
975 defined, the board configuration must define several
976 SPI configuration items (port pins to use, etc). For
977 an example, see include/configs/sacsng.h.
979 - FPGA Support: CONFIG_FPGA_COUNT
981 Specify the number of FPGA devices to support.
985 Used to specify the types of FPGA devices. For
987 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
989 CFG_FPGA_PROG_FEEDBACK
991 Enable printing of hash marks during FPGA
996 Enable checks on FPGA configuration interface busy
997 status by the configuration function. This option
998 will require a board or device specific function to
1003 If defined, a function that provides delays in the
1004 FPGA configuration driver.
1006 CFG_FPGA_CHECK_CTRLC
1008 Allow Control-C to interrupt FPGA configuration
1010 CFG_FPGA_CHECK_ERROR
1012 Check for configuration errors during FPGA bitfile
1013 loading. For example, abort during Virtex II
1014 configuration if the INIT_B line goes low (which
1015 indicated a CRC error).
1019 Maximum time to wait for the INIT_B line to deassert
1020 after PROB_B has been deasserted during a Virtex II
1021 FPGA configuration sequence. The default time is 500 mS.
1025 Maximum time to wait for BUSY to deassert during
1026 Virtex II FPGA configuration. The default is 5 mS.
1028 CFG_FPGA_WAIT_CONFIG
1030 Time to wait after FPGA configuration. The default is
1033 - FPGA Support: CONFIG_FPGA_COUNT
1035 Specify the number of FPGA devices to support.
1039 Used to specify the types of FPGA devices. For example,
1040 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1042 CFG_FPGA_PROG_FEEDBACK
1044 Enable printing of hash marks during FPGA configuration.
1048 Enable checks on FPGA configuration interface busy
1049 status by the configuration function. This option
1050 will require a board or device specific function to
1055 If defined, a function that provides delays in the FPGA
1056 configuration driver.
1058 CFG_FPGA_CHECK_CTRLC
1059 Allow Control-C to interrupt FPGA configuration
1061 CFG_FPGA_CHECK_ERROR
1063 Check for configuration errors during FPGA bitfile
1064 loading. For example, abort during Virtex II
1065 configuration if the INIT_B line goes low (which
1066 indicated a CRC error).
1070 Maximum time to wait for the INIT_B line to deassert
1071 after PROB_B has been deasserted during a Virtex II
1072 FPGA configuration sequence. The default time is 500
1077 Maximum time to wait for BUSY to deassert during
1078 Virtex II FPGA configuration. The default is 5 mS.
1080 CFG_FPGA_WAIT_CONFIG
1082 Time to wait after FPGA configuration. The default is
1085 - Configuration Management:
1088 If defined, this string will be added to the U-Boot
1089 version information (U_BOOT_VERSION)
1091 - Vendor Parameter Protection:
1093 U-Boot considers the values of the environment
1094 variables "serial#" (Board Serial Number) and
1095 "ethaddr" (Ethernet Address) to bb parameters that
1096 are set once by the board vendor / manufacturer, and
1097 protects these variables from casual modification by
1098 the user. Once set, these variables are read-only,
1099 and write or delete attempts are rejected. You can
1100 change this behviour:
1102 If CONFIG_ENV_OVERWRITE is #defined in your config
1103 file, the write protection for vendor parameters is
1104 completely disabled. Anybody can change or delete
1107 Alternatively, if you #define _both_ CONFIG_ETHADDR
1108 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1109 ethernet address is installed in the environment,
1110 which can be changed exactly ONCE by the user. [The
1111 serial# is unaffected by this, i. e. it remains
1117 Define this variable to enable the reservation of
1118 "protected RAM", i. e. RAM which is not overwritten
1119 by U-Boot. Define CONFIG_PRAM to hold the number of
1120 kB you want to reserve for pRAM. You can overwrite
1121 this default value by defining an environment
1122 variable "pram" to the number of kB you want to
1123 reserve. Note that the board info structure will
1124 still show the full amount of RAM. If pRAM is
1125 reserved, a new environment variable "mem" will
1126 automatically be defined to hold the amount of
1127 remaining RAM in a form that can be passed as boot
1128 argument to Linux, for instance like that:
1130 setenv bootargs ... mem=\$(mem)
1133 This way you can tell Linux not to use this memory,
1134 either, which results in a memory region that will
1135 not be affected by reboots.
1137 *WARNING* If your board configuration uses automatic
1138 detection of the RAM size, you must make sure that
1139 this memory test is non-destructive. So far, the
1140 following board configurations are known to be
1143 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1144 HERMES, IP860, RPXlite, LWMON, LANTEC,
1145 PCU_E, FLAGADM, TQM8260
1150 Define this variable to stop the system in case of a
1151 fatal error, so that you have to reset it manually.
1152 This is probably NOT a good idea for an embedded
1153 system where you want to system to reboot
1154 automatically as fast as possible, but it may be
1155 useful during development since you can try to debug
1156 the conditions that lead to the situation.
1158 CONFIG_NET_RETRY_COUNT
1160 This variable defines the number of retries for
1161 network operations like ARP, RARP, TFTP, or BOOTP
1162 before giving up the operation. If not defined, a
1163 default value of 5 is used.
1165 - Command Interpreter:
1168 Define this variable to enable the "hush" shell (from
1169 Busybox) as command line interpreter, thus enabling
1170 powerful command line syntax like
1171 if...then...else...fi conditionals or `&&' and '||'
1172 constructs ("shell scripts").
1174 If undefined, you get the old, much simpler behaviour
1175 with a somewhat smaller memory footprint.
1180 This defines the secondary prompt string, which is
1181 printed when the command interpreter needs more input
1182 to complete a command. Usually "> ".
1186 In the current implementation, the local variables
1187 space and global environment variables space are
1188 separated. Local variables are those you define by
1189 simply typing like `name=value'. To access a local
1190 variable later on, you have write `$name' or
1191 `${name}'; variable directly by typing say `$name' at
1194 Global environment variables are those you use
1195 setenv/printenv to work with. To run a command stored
1196 in such a variable, you need to use the run command,
1197 and you must not use the '$' sign to access them.
1199 To store commands and special characters in a
1200 variable, please use double quotation marks
1201 surrounding the whole text of the variable, instead
1202 of the backslashes before semicolons and special
1205 - Default Environment
1206 CONFIG_EXTRA_ENV_SETTINGS
1208 Define this to contain any number of null terminated
1209 strings (variable = value pairs) that will be part of
1210 the default enviroment compiled into the boot image.
1212 For example, place something like this in your
1213 board's config file:
1215 #define CONFIG_EXTRA_ENV_SETTINGS \
1219 Warning: This method is based on knowledge about the
1220 internal format how the environment is stored by the
1221 U-Boot code. This is NOT an official, exported
1222 interface! Although it is unlikely that this format
1223 will change soon, but there is no guarantee either.
1224 You better know what you are doing here.
1226 Note: overly (ab)use of the default environment is
1227 discouraged. Make sure to check other ways to preset
1228 the environment like the autoscript function or the
1231 - Show boot progress
1232 CONFIG_SHOW_BOOT_PROGRESS
1234 Defining this option allows to add some board-
1235 specific code (calling a user-provided function
1236 "show_boot_progress(int)") that enables you to show
1237 the system's boot progress on some display (for
1238 example, some LED's) on your board. At the moment,
1239 the following checkpoints are implemented:
1242 1 common/cmd_bootm.c before attempting to boot an image
1243 -1 common/cmd_bootm.c Image header has bad magic number
1244 2 common/cmd_bootm.c Image header has correct magic number
1245 -2 common/cmd_bootm.c Image header has bad checksum
1246 3 common/cmd_bootm.c Image header has correct checksum
1247 -3 common/cmd_bootm.c Image data has bad checksum
1248 4 common/cmd_bootm.c Image data has correct checksum
1249 -4 common/cmd_bootm.c Image is for unsupported architecture
1250 5 common/cmd_bootm.c Architecture check OK
1251 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1252 6 common/cmd_bootm.c Image Type check OK
1253 -6 common/cmd_bootm.c gunzip uncompression error
1254 -7 common/cmd_bootm.c Unimplemented compression type
1255 7 common/cmd_bootm.c Uncompression OK
1256 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1257 8 common/cmd_bootm.c Image Type check OK
1258 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1259 9 common/cmd_bootm.c Start initial ramdisk verification
1260 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1261 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1262 10 common/cmd_bootm.c Ramdisk header is OK
1263 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1264 11 common/cmd_bootm.c Ramdisk data has correct checksum
1265 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1266 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1267 13 common/cmd_bootm.c Start multifile image verification
1268 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1269 15 common/cmd_bootm.c All preparation done, transferring control to OS
1271 -1 common/cmd_doc.c Bad usage of "doc" command
1272 -1 common/cmd_doc.c No boot device
1273 -1 common/cmd_doc.c Unknown Chip ID on boot device
1274 -1 common/cmd_doc.c Read Error on boot device
1275 -1 common/cmd_doc.c Image header has bad magic number
1277 -1 common/cmd_ide.c Bad usage of "ide" command
1278 -1 common/cmd_ide.c No boot device
1279 -1 common/cmd_ide.c Unknown boot device
1280 -1 common/cmd_ide.c Unknown partition table
1281 -1 common/cmd_ide.c Invalid partition type
1282 -1 common/cmd_ide.c Read Error on boot device
1283 -1 common/cmd_ide.c Image header has bad magic number
1285 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1291 [so far only for SMDK2400 and TRAB boards]
1293 - Modem support endable:
1294 CONFIG_MODEM_SUPPORT
1296 - RTS/CTS Flow control enable:
1299 - Modem debug support:
1300 CONFIG_MODEM_SUPPORT_DEBUG
1302 Enables debugging stuff (char screen[1024], dbg())
1303 for modem support. Useful only with BDI2000.
1307 In the target system modem support is enabled when a
1308 specific key (key combination) is pressed during
1309 power-on. Otherwise U-Boot will boot normally
1310 (autoboot). The key_pressed() fuction is called from
1311 board_init(). Currently key_pressed() is a dummy
1312 function, returning 1 and thus enabling modem
1315 If there are no modem init strings in the
1316 environment, U-Boot proceed to autoboot; the
1317 previous output (banner, info printfs) will be
1320 See also: doc/README.Modem
1325 Configuration Settings:
1326 -----------------------
1328 - CFG_LONGHELP: Defined when you want long help messages included;
1329 undefine this when you're short of memory.
1331 - CFG_PROMPT: This is what U-Boot prints on the console to
1332 prompt for user input.
1334 - CFG_CBSIZE: Buffer size for input from the Console
1336 - CFG_PBSIZE: Buffer size for Console output
1338 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1340 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1341 the application (usually a Linux kernel) when it is
1344 - CFG_BAUDRATE_TABLE:
1345 List of legal baudrate settings for this board.
1347 - CFG_CONSOLE_INFO_QUIET
1348 Suppress display of console information at boot.
1350 - CFG_CONSOLE_IS_IN_ENV
1351 If the board specific function
1352 extern int overwrite_console (void);
1353 returns 1, the stdin, stderr and stdout are switched to the
1354 serial port, else the settings in the environment are used.
1356 - CFG_CONSOLE_OVERWRITE_ROUTINE
1357 Enable the call to overwrite_console().
1359 - CFG_CONSOLE_ENV_OVERWRITE
1360 Enable overwrite of previous console environment settings.
1362 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1363 Begin and End addresses of the area used by the
1367 Enable an alternate, more extensive memory test.
1369 - CFG_TFTP_LOADADDR:
1370 Default load address for network file downloads
1372 - CFG_LOADS_BAUD_CHANGE:
1373 Enable temporary baudrate change while serial download
1376 Physical start address of SDRAM. _Must_ be 0 here.
1379 Physical start address of Motherboard I/O (if using a
1383 Physical start address of Flash memory.
1386 Physical start address of boot monitor code (set by
1387 make config files to be same as the text base address
1388 (TEXT_BASE) used when linking) - same as
1389 CFG_FLASH_BASE when booting from flash.
1392 Size of memory reserved for monitor code
1395 Size of DRAM reserved for malloc() use.
1398 Maximum size of memory mapped by the startup code of
1399 the Linux kernel; all data that must be processed by
1400 the Linux kernel (bd_info, boot arguments, eventually
1401 initrd image) must be put below this limit.
1403 - CFG_MAX_FLASH_BANKS:
1404 Max number of Flash memory banks
1406 - CFG_MAX_FLASH_SECT:
1407 Max number of sectors on a Flash chip
1409 - CFG_FLASH_ERASE_TOUT:
1410 Timeout for Flash erase operations (in ms)
1412 - CFG_FLASH_WRITE_TOUT:
1413 Timeout for Flash write operations (in ms)
1415 - CFG_DIRECT_FLASH_TFTP:
1417 Enable TFTP transfers directly to flash memory;
1418 without this option such a download has to be
1419 performed in two steps: (1) download to RAM, and (2)
1420 copy from RAM to flash.
1422 The two-step approach is usually more reliable, since
1423 you can check if the download worked before you erase
1424 the flash, but in some situations (when sytem RAM is
1425 too limited to allow for a tempory copy of the
1426 downloaded image) this option may be very useful.
1429 Define if the flash driver uses extra elements in the
1430 common flash structure for storing flash geometry
1432 The following definitions that deal with the placement and management
1433 of environment data (variable area); in general, we support the
1434 following configurations:
1436 - CFG_ENV_IS_IN_FLASH:
1438 Define this if the environment is in flash memory.
1440 a) The environment occupies one whole flash sector, which is
1441 "embedded" in the text segment with the U-Boot code. This
1442 happens usually with "bottom boot sector" or "top boot
1443 sector" type flash chips, which have several smaller
1444 sectors at the start or the end. For instance, such a
1445 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1446 such a case you would place the environment in one of the
1447 4 kB sectors - with U-Boot code before and after it. With
1448 "top boot sector" type flash chips, you would put the
1449 environment in one of the last sectors, leaving a gap
1450 between U-Boot and the environment.
1454 Offset of environment data (variable area) to the
1455 beginning of flash memory; for instance, with bottom boot
1456 type flash chips the second sector can be used: the offset
1457 for this sector is given here.
1459 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1463 This is just another way to specify the start address of
1464 the flash sector containing the environment (instead of
1467 - CFG_ENV_SECT_SIZE:
1469 Size of the sector containing the environment.
1472 b) Sometimes flash chips have few, equal sized, BIG sectors.
1473 In such a case you don't want to spend a whole sector for
1478 If you use this in combination with CFG_ENV_IS_IN_FLASH
1479 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1480 of this flash sector for the environment. This saves
1481 memory for the RAM copy of the environment.
1483 It may also save flash memory if you decide to use this
1484 when your environment is "embedded" within U-Boot code,
1485 since then the remainder of the flash sector could be used
1486 for U-Boot code. It should be pointed out that this is
1487 STRONGLY DISCOURAGED from a robustness point of view:
1488 updating the environment in flash makes it always
1489 necessary to erase the WHOLE sector. If something goes
1490 wrong before the contents has been restored from a copy in
1491 RAM, your target system will be dead.
1493 - CFG_ENV_ADDR_REDUND
1496 These settings describe a second storage area used to hold
1497 a redundand copy of the environment data, so that there is
1498 a valid backup copy in case there is a power failure during
1499 a "saveenv" operation.
1501 BE CAREFUL! Any changes to the flash layout, and some changes to the
1502 source code will make it necessary to adapt <board>/u-boot.lds*
1506 - CFG_ENV_IS_IN_NVRAM:
1508 Define this if you have some non-volatile memory device
1509 (NVRAM, battery buffered SRAM) which you want to use for the
1515 These two #defines are used to determin the memory area you
1516 want to use for environment. It is assumed that this memory
1517 can just be read and written to, without any special
1520 BE CAREFUL! The first access to the environment happens quite early
1521 in U-Boot initalization (when we try to get the setting of for the
1522 console baudrate). You *MUST* have mappend your NVRAM area then, or
1525 Please note that even with NVRAM we still use a copy of the
1526 environment in RAM: we could work on NVRAM directly, but we want to
1527 keep settings there always unmodified except somebody uses "saveenv"
1528 to save the current settings.
1531 - CFG_ENV_IS_IN_EEPROM:
1533 Use this if you have an EEPROM or similar serial access
1534 device and a driver for it.
1539 These two #defines specify the offset and size of the
1540 environment area within the total memory of your EEPROM.
1542 - CFG_I2C_EEPROM_ADDR:
1543 If defined, specified the chip address of the EEPROM device.
1544 The default address is zero.
1546 - CFG_EEPROM_PAGE_WRITE_BITS:
1547 If defined, the number of bits used to address bytes in a
1548 single page in the EEPROM device. A 64 byte page, for example
1549 would require six bits.
1551 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1552 If defined, the number of milliseconds to delay between
1553 page writes. The default is zero milliseconds.
1555 - CFG_I2C_EEPROM_ADDR_LEN:
1556 The length in bytes of the EEPROM memory array address. Note
1557 that this is NOT the chip address length!
1560 The size in bytes of the EEPROM device.
1563 - CFG_SPI_INIT_OFFSET
1565 Defines offset to the initial SPI buffer area in DPRAM. The
1566 area is used at an early stage (ROM part) if the environment
1567 is configured to reside in the SPI EEPROM: We need a 520 byte
1568 scratch DPRAM area. It is used between the two initialization
1569 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1570 to be a good choice since it makes it far enough from the
1571 start of the data area as well as from the stack pointer.
1573 Please note that the environment is read-only as long as the monitor
1574 has been relocated to RAM and a RAM copy of the environment has been
1575 created; also, when using EEPROM you will have to use getenv_r()
1576 until then to read environment variables.
1578 The environment is protected by a CRC32 checksum. Before the monitor
1579 is relocated into RAM, as a result of a bad CRC you will be working
1580 with the compiled-in default environment - *silently*!!! [This is
1581 necessary, because the first environment variable we need is the
1582 "baudrate" setting for the console - if we have a bad CRC, we don't
1583 have any device yet where we could complain.]
1585 Note: once the monitor has been relocated, then it will complain if
1586 the default environment is used; a new CRC is computed as soon as you
1587 use the "saveenv" command to store a valid environment.
1590 Low Level (hardware related) configuration options:
1591 ---------------------------------------------------
1593 - CFG_CACHELINE_SIZE:
1594 Cache Line Size of the CPU.
1597 Default address of the IMMR after system reset.
1598 Needed on some 8260 systems (MPC8260ADS and RPXsuper)
1599 to be able to adjust the position of the IMMR
1600 register after a reset.
1602 - Floppy Disk Support:
1603 CFG_FDC_DRIVE_NUMBER
1605 the default drive number (default value 0)
1609 defines the spacing between fdc chipset registers
1614 defines the offset of register from address. It
1615 depends on which part of the data bus is connected to
1616 the fdc chipset. (default value 0)
1618 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1619 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1622 if CFG_FDC_HW_INIT is defined, then the function
1623 fdc_hw_init() is called at the beginning of the FDC
1624 setup. fdc_hw_init() must be provided by the board
1625 source code. It is used to make hardware dependant
1628 - CFG_IMMR: Physical address of the Internal Memory Mapped
1629 Register; DO NOT CHANGE! (11-4)
1630 [MPC8xx systems only]
1632 - CFG_INIT_RAM_ADDR:
1634 Start address of memory area tha can be used for
1635 initial data and stack; please note that this must be
1636 writable memory that is working WITHOUT special
1637 initialization, i. e. you CANNOT use normal RAM which
1638 will become available only after programming the
1639 memory controller and running certain initialization
1642 U-Boot uses the following memory types:
1643 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1644 - MPC824X: data cache
1645 - PPC4xx: data cache
1647 - CFG_GBL_DATA_OFFSET:
1649 Offset of the initial data structure in the memory
1650 area defined by CFG_INIT_RAM_ADDR. Usually
1651 CFG_GBL_DATA_OFFSET is chosen such that the initial
1652 data is located at the end of the available space
1653 (sometimes written as (CFG_INIT_RAM_END -
1654 CFG_INIT_DATA_SIZE), and the initial stack is just
1655 below that area (growing from (CFG_INIT_RAM_ADDR +
1656 CFG_GBL_DATA_OFFSET) downward.
1659 On the MPC824X (or other systems that use the data
1660 cache for initial memory) the address chosen for
1661 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1662 point to an otherwise UNUSED address space between
1663 the top of RAM and the start of the PCI space.
1665 - CFG_SIUMCR: SIU Module Configuration (11-6)
1667 - CFG_SYPCR: System Protection Control (11-9)
1669 - CFG_TBSCR: Time Base Status and Control (11-26)
1671 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1673 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1675 - CFG_SCCR: System Clock and reset Control Register (15-27)
1677 - CFG_OR_TIMING_SDRAM:
1681 periodic timer for refresh
1683 - CFG_DER: Debug Event Register (37-47)
1685 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1686 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1687 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1689 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1691 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1692 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1693 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1694 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1696 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1697 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1698 Machine Mode Register and Memory Periodic Timer
1699 Prescaler definitions (SDRAM timing)
1701 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1702 enable I2C microcode relocation patch (MPC8xx);
1703 define relocation offset in DPRAM [DSP2]
1705 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1706 enable SPI microcode relocation patch (MPC8xx);
1707 define relocation offset in DPRAM [SCC4]
1710 Use OSCM clock mode on MBX8xx board. Be careful,
1711 wrong setting might damage your board. Read
1712 doc/README.MBX before setting this variable!
1714 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1715 Offset of the bootmode word in DPRAM used by post
1716 (Power On Self Tests). This definition overrides
1717 #define'd default value in commproc.h resp.
1720 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1721 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1722 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1723 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1724 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1725 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1726 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1727 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1728 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1730 Building the Software:
1731 ======================
1733 Building U-Boot has been tested in native PPC environments (on a
1734 PowerBook G3 running LinuxPPC 2000) and in cross environments
1735 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1738 If you are not using a native PPC environment, it is assumed that you
1739 have the GNU cross compiling tools available in your path and named
1740 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1741 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1742 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1745 CROSS_COMPILE = ppc_4xx-
1748 U-Boot is intended to be simple to build. After installing the
1749 sources you must configure U-Boot for one specific board type. This
1754 where "NAME_config" is the name of one of the existing
1755 configurations; the following names are supported:
1757 ADCIOP_config GTH_config TQM850L_config
1758 ADS860_config IP860_config TQM855L_config
1759 AR405_config IVML24_config TQM860L_config
1760 CANBT_config IVMS8_config WALNUT405_config
1761 CPCI405_config LANTEC_config cogent_common_config
1762 CPCIISER4_config MBX_config cogent_mpc8260_config
1763 CU824_config MBX860T_config cogent_mpc8xx_config
1764 ESTEEM192E_config RPXlite_config hermes_config
1765 ETX094_config RPXsuper_config hymod_config
1766 FADS823_config SM850_config lwmon_config
1767 FADS850SAR_config SPD823TS_config pcu_e_config
1768 FADS860T_config SXNI855T_config rsdproto_config
1769 FPS850L_config Sandpoint8240_config sbc8260_config
1770 GENIETV_config TQM823L_config PIP405_config
1771 GEN860T_config EBONY_config FPS860L_config
1772 ELPT860_config cmi_mpc5xx_config NETVIA_config
1774 Note: for some board special configuration names may exist; check if
1775 additional information is available from the board vendor; for
1776 instance, the TQM8xxL systems run normally at 50 MHz and use a
1777 SCC for 10baseT ethernet; there are also systems with 80 MHz
1778 CPU clock, and an optional Fast Ethernet module is available
1779 for CPU's with FEC. You can select such additional "features"
1780 when chosing the configuration, i. e.
1783 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1785 make TQM860L_FEC_config
1786 - will configure for a TQM860L at 50MHz with FEC for ethernet
1788 make TQM860L_80MHz_config
1789 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1792 make TQM860L_FEC_80MHz_config
1793 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1795 make TQM823L_LCD_config
1796 - will configure for a TQM823L with U-Boot console on LCD
1798 make TQM823L_LCD_80MHz_config
1799 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1805 Finally, type "make all", and you should get some working U-Boot
1806 images ready for downlod to / installation on your system:
1808 - "u-boot.bin" is a raw binary image
1809 - "u-boot" is an image in ELF binary format
1810 - "u-boot.srec" is in Motorola S-Record format
1813 Please be aware that the Makefiles assume you are using GNU make, so
1814 for instance on NetBSD you might need to use "gmake" instead of
1818 If the system board that you have is not listed, then you will need
1819 to port U-Boot to your hardware platform. To do this, follow these
1822 1. Add a new configuration option for your board to the toplevel
1823 "Makefile" and to the "MAKEALL" script, using the existing
1824 entries as examples. Note that here and at many other places
1825 boards and other names are listed alphabetically sorted. Please
1827 2. Create a new directory to hold your board specific code. Add any
1828 files you need. In your board directory, you will need at least
1829 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1830 3. Create a new configuration file "include/configs/<board>.h" for
1832 3. If you're porting U-Boot to a new CPU, then also create a new
1833 directory to hold your CPU specific code. Add any files you need.
1834 4. Run "make <board>_config" with your new name.
1835 5. Type "make", and you should get a working "u-boot.srec" file
1836 to be installed on your target system.
1837 6. Debug and solve any problems that might arise.
1838 [Of course, this last step is much harder than it sounds.]
1841 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1842 ==============================================================
1844 If you have modified U-Boot sources (for instance added a new board
1845 or support for new devices, a new CPU, etc.) you are expected to
1846 provide feedback to the other developers. The feedback normally takes
1847 the form of a "patch", i. e. a context diff against a certain (latest
1848 official or latest in CVS) version of U-Boot sources.
1850 But before you submit such a patch, please verify that your modifi-
1851 cation did not break existing code. At least make sure that *ALL* of
1852 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1853 just run the "MAKEALL" script, which will configure and build U-Boot
1854 for ALL supported system. Be warned, this will take a while. You can
1855 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1856 environment variable to the script, i. e. to use the cross tools from
1857 MontaVista's Hard Hat Linux you can type
1859 CROSS_COMPILE=ppc_8xx- MAKEALL
1861 or to build on a native PowerPC system you can type
1863 CROSS_COMPILE=' ' MAKEALL
1865 See also "U-Boot Porting Guide" below.
1869 Monitor Commands - Overview:
1870 ============================
1872 go - start application at address 'addr'
1873 run - run commands in an environment variable
1874 bootm - boot application image from memory
1875 bootp - boot image via network using BootP/TFTP protocol
1876 tftpboot- boot image via network using TFTP protocol
1877 and env variables "ipaddr" and "serverip"
1878 (and eventually "gatewayip")
1879 rarpboot- boot image via network using RARP/TFTP protocol
1880 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
1881 loads - load S-Record file over serial line
1882 loadb - load binary file over serial line (kermit mode)
1884 mm - memory modify (auto-incrementing)
1885 nm - memory modify (constant address)
1886 mw - memory write (fill)
1888 cmp - memory compare
1889 crc32 - checksum calculation
1890 imd - i2c memory display
1891 imm - i2c memory modify (auto-incrementing)
1892 inm - i2c memory modify (constant address)
1893 imw - i2c memory write (fill)
1894 icrc32 - i2c checksum calculation
1895 iprobe - probe to discover valid I2C chip addresses
1896 iloop - infinite loop on address range
1897 isdram - print SDRAM configuration information
1898 sspi - SPI utility commands
1899 base - print or set address offset
1900 printenv- print environment variables
1901 setenv - set environment variables
1902 saveenv - save environment variables to persistent storage
1903 protect - enable or disable FLASH write protection
1904 erase - erase FLASH memory
1905 flinfo - print FLASH memory information
1906 bdinfo - print Board Info structure
1907 iminfo - print header information for application image
1908 coninfo - print console devices and informations
1909 ide - IDE sub-system
1910 loop - infinite loop on address range
1911 mtest - simple RAM test
1912 icache - enable or disable instruction cache
1913 dcache - enable or disable data cache
1914 reset - Perform RESET of the CPU
1915 echo - echo args to console
1916 version - print monitor version
1917 help - print online help
1918 ? - alias for 'help'
1921 Monitor Commands - Detailed Description:
1922 ========================================
1926 For now: just type "help <command>".
1929 Environment Variables:
1930 ======================
1932 U-Boot supports user configuration using Environment Variables which
1933 can be made persistent by saving to Flash memory.
1935 Environment Variables are set using "setenv", printed using
1936 "printenv", and saved to Flash using "saveenv". Using "setenv"
1937 without a value can be used to delete a variable from the
1938 environment. As long as you don't save the environment you are
1939 working with an in-memory copy. In case the Flash area containing the
1940 environment is erased by accident, a default environment is provided.
1942 Some configuration options can be set using Environment Variables:
1944 baudrate - see CONFIG_BAUDRATE
1946 bootdelay - see CONFIG_BOOTDELAY
1948 bootcmd - see CONFIG_BOOTCOMMAND
1950 bootargs - Boot arguments when booting an RTOS image
1952 bootfile - Name of the image to load with TFTP
1954 autoload - if set to "no" (any string beginning with 'n'),
1955 "bootp" will just load perform a lookup of the
1956 configuration from the BOOTP server, but not try to
1957 load any image using TFTP
1959 autostart - if set to "yes", an image loaded using the "bootp",
1960 "rarpboot", "tftpboot" or "diskboot" commands will
1961 be automatically started (by internally calling
1964 If set to "no", a standalone image passed to the
1965 "bootm" command will be copied to the load address
1966 (and eventually uncompressed), but NOT be started.
1967 This can be used to load and uncompress arbitrary
1970 initrd_high - restrict positioning of initrd images:
1971 If this variable is not set, initrd images will be
1972 copied to the highest possible address in RAM; this
1973 is usually what you want since it allows for
1974 maximum initrd size. If for some reason you want to
1975 make sure that the initrd image is loaded below the
1976 CFG_BOOTMAPSZ limit, you can set this environment
1977 variable to a value of "no" or "off" or "0".
1978 Alternatively, you can set it to a maximum upper
1979 address to use (U-Boot will still check that it
1980 does not overwrite the U-Boot stack and data).
1982 For instance, when you have a system with 16 MB
1983 RAM, and want to reseve 4 MB from use by Linux,
1984 you can do this by adding "mem=12M" to the value of
1985 the "bootargs" variable. However, now you must make
1986 sure, that the initrd image is placed in the first
1987 12 MB as well - this can be done with
1989 setenv initrd_high 00c00000
1991 If you set initrd_high to 0xFFFFFFFF, this is an
1992 indication to U-Boot that all addresses are legal
1993 for the Linux kernel, including addresses in flash
1994 memory. In this case U-Boot will NOT COPY the
1995 ramdisk at all. This may be useful to reduce the
1996 boot time on your system, but requires that this
1997 feature is supported by your Linux kernel.
1999 ipaddr - IP address; needed for tftpboot command
2001 loadaddr - Default load address for commands like "bootp",
2002 "rarpboot", "tftpboot", "loadb" or "diskboot"
2004 loads_echo - see CONFIG_LOADS_ECHO
2006 serverip - TFTP server IP address; needed for tftpboot command
2008 bootretry - see CONFIG_BOOT_RETRY_TIME
2010 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2012 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2015 The following environment variables may be used and automatically
2016 updated by the network boot commands ("bootp" and "rarpboot"),
2017 depending the information provided by your boot server:
2019 bootfile - see above
2020 dnsip - IP address of your Domain Name Server
2021 gatewayip - IP address of the Gateway (Router) to use
2022 hostname - Target hostname
2024 netmask - Subnet Mask
2025 rootpath - Pathname of the root filesystem on the NFS server
2026 serverip - see above
2029 There are two special Environment Variables:
2031 serial# - contains hardware identification information such
2032 as type string and/or serial number
2033 ethaddr - Ethernet address
2035 These variables can be set only once (usually during manufacturing of
2036 the board). U-Boot refuses to delete or overwrite these variables
2037 once they have been set once.
2040 Further special Environment Variables:
2042 ver - Contains the U-Boot version string as printed
2043 with the "version" command. This variable is
2044 readonly (see CONFIG_VERSION_VARIABLE).
2047 Please note that changes to some configuration parameters may take
2048 only effect after the next boot (yes, that's just like Windoze :-).
2051 Command Line Parsing:
2052 =====================
2054 There are two different command line parsers available with U-Boot:
2055 the old "simple" one, and the much more pwerful "hush" shell:
2057 Old, simple command line parser:
2058 --------------------------------
2060 - supports environment variables (through setenv / saveenv commands)
2061 - several commands on one line, separated by ';'
2062 - variable substitution using "... $(name) ..." syntax
2063 - special characters ('$', ';') can be escaped by prefixing with '\',
2065 setenv bootcmd bootm \$(address)
2066 - You can also escape text by enclosing in single apostrophes, for example:
2067 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2072 - similar to Bourne shell, with control structures like
2073 if...then...else...fi, for...do...done; while...do...done,
2074 until...do...done, ...
2075 - supports environment ("global") variables (through setenv / saveenv
2076 commands) and local shell variables (through standard shell syntax
2077 "name=value"); only environment variables can be used with "run"
2083 (1) If a command line (or an environment variable executed by a "run"
2084 command) contains several commands separated by semicolon, and
2085 one of these commands fails, then the remaining commands will be
2088 (2) If you execute several variables with one call to run (i. e.
2089 calling run with a list af variables as arguments), any failing
2090 command will cause "run" to terminate, i. e. the remaining
2091 variables are not executed.
2093 Note for Redundant Ethernet Interfaces:
2094 =======================================
2096 Some boards come with redundand ethernet interfaces; U-Boot supports
2097 such configurations and is capable of automatic selection of a
2098 "working" interface when needed. MAC assignemnt works as follows:
2100 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2101 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2102 "eth1addr" (=>eth1), "eth2addr", ...
2104 If the network interface stores some valid MAC address (for instance
2105 in SROM), this is used as default address if there is NO correspon-
2106 ding setting in the environment; if the corresponding environment
2107 variable is set, this overrides the settings in the card; that means:
2109 o If the SROM has a valid MAC address, and there is no address in the
2110 environment, the SROM's address is used.
2112 o If there is no valid address in the SROM, and a definition in the
2113 environment exists, then the value from the environment variable is
2116 o If both the SROM and the environment contain a MAC address, and
2117 both addresses are the same, this MAC address is used.
2119 o If both the SROM and the environment contain a MAC address, and the
2120 addresses differ, the value from the environment is used and a
2123 o If neither SROM nor the environment contain a MAC address, an error
2131 The "boot" commands of this monitor operate on "image" files which
2132 can be basicly anything, preceeded by a special header; see the
2133 definitions in include/image.h for details; basicly, the header
2134 defines the following image properties:
2136 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2137 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2138 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2139 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS).
2140 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2141 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2142 Currently supported: PowerPC).
2143 * Compression Type (Provisions for uncompressed, gzip, bzip2;
2144 Currently supported: uncompressed, gzip).
2150 The header is marked by a special Magic Number, and both the header
2151 and the data portions of the image are secured against corruption by
2158 Although U-Boot should support any OS or standalone application
2159 easily, Linux has always been in the focus during the design of
2162 U-Boot includes many features that so far have been part of some
2163 special "boot loader" code within the Linux kernel. Also, any
2164 "initrd" images to be used are no longer part of one big Linux image;
2165 instead, kernel and "initrd" are separate images. This implementation
2166 serves serveral purposes:
2168 - the same features can be used for other OS or standalone
2169 applications (for instance: using compressed images to reduce the
2170 Flash memory footprint)
2172 - it becomes much easier to port new Linux kernel versions because
2173 lots of low-level, hardware dependend stuff are done by U-Boot
2175 - the same Linux kernel image can now be used with different "initrd"
2176 images; of course this also means that different kernel images can
2177 be run with the same "initrd". This makes testing easier (you don't
2178 have to build a new "zImage.initrd" Linux image when you just
2179 change a file in your "initrd"). Also, a field-upgrade of the
2180 software is easier now.
2186 Porting Linux to U-Boot based systems:
2187 ---------------------------------------
2189 U-Boot cannot save you from doing all the necessary modifications to
2190 configure the Linux device drivers for use with your target hardware
2191 (no, we don't intend to provide a full virtual machine interface to
2194 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2196 Just make sure your machine specific header file (for instance
2197 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2198 Information structure as we define in include/u-boot.h, and make
2199 sure that your definition of IMAP_ADDR uses the same value as your
2200 U-Boot configuration in CFG_IMMR.
2203 Configuring the Linux kernel:
2204 -----------------------------
2206 No specific requirements for U-Boot. Make sure you have some root
2207 device (initial ramdisk, NFS) for your target system.
2210 Building a Linux Image:
2211 -----------------------
2213 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2214 not used. If you use recent kernel source, a new build target
2215 "uImage" will exist which automatically builds an image usable by
2216 U-Boot. Most older kernels also have support for a "pImage" target,
2217 which was introduced for our predecessor project PPCBoot and uses a
2218 100% compatible format.
2227 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2228 encapsulate a compressed Linux kernel image with header information,
2229 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2231 * build a standard "vmlinux" kernel image (in ELF binary format):
2233 * convert the kernel into a raw binary image:
2235 ${CROSS_COMPILE}-objcopy -O binary \
2236 -R .note -R .comment \
2237 -S vmlinux linux.bin
2239 * compress the binary image:
2243 * package compressed binary image for U-Boot:
2245 mkimage -A ppc -O linux -T kernel -C gzip \
2246 -a 0 -e 0 -n "Linux Kernel Image" \
2247 -d linux.bin.gz uImage
2250 The "mkimage" tool can also be used to create ramdisk images for use
2251 with U-Boot, either separated from the Linux kernel image, or
2252 combined into one file. "mkimage" encapsulates the images with a 64
2253 byte header containing information about target architecture,
2254 operating system, image type, compression method, entry points, time
2255 stamp, CRC32 checksums, etc.
2257 "mkimage" can be called in two ways: to verify existing images and
2258 print the header information, or to build new images.
2260 In the first form (with "-l" option) mkimage lists the information
2261 contained in the header of an existing U-Boot image; this includes
2262 checksum verification:
2264 tools/mkimage -l image
2265 -l ==> list image header information
2267 The second form (with "-d" option) is used to build a U-Boot image
2268 from a "data file" which is used as image payload:
2270 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2271 -n name -d data_file image
2272 -A ==> set architecture to 'arch'
2273 -O ==> set operating system to 'os'
2274 -T ==> set image type to 'type'
2275 -C ==> set compression type 'comp'
2276 -a ==> set load address to 'addr' (hex)
2277 -e ==> set entry point to 'ep' (hex)
2278 -n ==> set image name to 'name'
2279 -d ==> use image data from 'datafile'
2281 Right now, all Linux kernels use the same load address (0x00000000),
2282 but the entry point address depends on the kernel version:
2284 - 2.2.x kernels have the entry point at 0x0000000C,
2285 - 2.3.x and later kernels have the entry point at 0x00000000.
2287 So a typical call to build a U-Boot image would read:
2289 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2290 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2291 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2292 > examples/uImage.TQM850L
2293 Image Name: 2.4.4 kernel for TQM850L
2294 Created: Wed Jul 19 02:34:59 2000
2295 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2296 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2297 Load Address: 0x00000000
2298 Entry Point: 0x00000000
2300 To verify the contents of the image (or check for corruption):
2302 -> tools/mkimage -l examples/uImage.TQM850L
2303 Image Name: 2.4.4 kernel for TQM850L
2304 Created: Wed Jul 19 02:34:59 2000
2305 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2306 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2307 Load Address: 0x00000000
2308 Entry Point: 0x00000000
2310 NOTE: for embedded systems where boot time is critical you can trade
2311 speed for memory and install an UNCOMPRESSED image instead: this
2312 needs more space in Flash, but boots much faster since it does not
2313 need to be uncompressed:
2315 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2316 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2317 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2318 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2319 > examples/uImage.TQM850L-uncompressed
2320 Image Name: 2.4.4 kernel for TQM850L
2321 Created: Wed Jul 19 02:34:59 2000
2322 Image Type: PowerPC Linux Kernel Image (uncompressed)
2323 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2324 Load Address: 0x00000000
2325 Entry Point: 0x00000000
2328 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2329 when your kernel is intended to use an initial ramdisk:
2331 -> tools/mkimage -n 'Simple Ramdisk Image' \
2332 > -A ppc -O linux -T ramdisk -C gzip \
2333 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2334 Image Name: Simple Ramdisk Image
2335 Created: Wed Jan 12 14:01:50 2000
2336 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2337 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2338 Load Address: 0x00000000
2339 Entry Point: 0x00000000
2342 Installing a Linux Image:
2343 -------------------------
2345 To downloading a U-Boot image over the serial (console) interface,
2346 you must convert the image to S-Record format:
2348 objcopy -I binary -O srec examples/image examples/image.srec
2350 The 'objcopy' does not understand the information in the U-Boot
2351 image header, so the resulting S-Record file will be relative to
2352 address 0x00000000. To load it to a given address, you need to
2353 specify the target address as 'offset' parameter with the 'loads'
2356 Example: install the image to address 0x40100000 (which on the
2357 TQM8xxL is in the first Flash bank):
2359 => erase 40100000 401FFFFF
2365 ## Ready for S-Record download ...
2366 ~>examples/image.srec
2367 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2369 15989 15990 15991 15992
2370 [file transfer complete]
2372 ## Start Addr = 0x00000000
2375 You can check the success of the download using the 'iminfo' command;
2376 this includes a checksum verification so you can be sure no data
2377 corruption happened:
2381 ## Checking Image at 40100000 ...
2382 Image Name: 2.2.13 for initrd on TQM850L
2383 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2384 Data Size: 335725 Bytes = 327 kB = 0 MB
2385 Load Address: 00000000
2386 Entry Point: 0000000c
2387 Verifying Checksum ... OK
2394 The "bootm" command is used to boot an application that is stored in
2395 memory (RAM or Flash). In case of a Linux kernel image, the contents
2396 of the "bootargs" environment variable is passed to the kernel as
2397 parameters. You can check and modify this variable using the
2398 "printenv" and "setenv" commands:
2401 => printenv bootargs
2402 bootargs=root=/dev/ram
2404 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2406 => printenv bootargs
2407 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2410 ## Booting Linux kernel at 40020000 ...
2411 Image Name: 2.2.13 for NFS on TQM850L
2412 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2413 Data Size: 381681 Bytes = 372 kB = 0 MB
2414 Load Address: 00000000
2415 Entry Point: 0000000c
2416 Verifying Checksum ... OK
2417 Uncompressing Kernel Image ... OK
2418 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
2419 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2420 time_init: decrementer frequency = 187500000/60
2421 Calibrating delay loop... 49.77 BogoMIPS
2422 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2425 If you want to boot a Linux kernel with initial ram disk, you pass
2426 the memory addreses of both the kernel and the initrd image (PPBCOOT
2427 format!) to the "bootm" command:
2429 => imi 40100000 40200000
2431 ## Checking Image at 40100000 ...
2432 Image Name: 2.2.13 for initrd on TQM850L
2433 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2434 Data Size: 335725 Bytes = 327 kB = 0 MB
2435 Load Address: 00000000
2436 Entry Point: 0000000c
2437 Verifying Checksum ... OK
2439 ## Checking Image at 40200000 ...
2440 Image Name: Simple Ramdisk Image
2441 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2442 Data Size: 566530 Bytes = 553 kB = 0 MB
2443 Load Address: 00000000
2444 Entry Point: 00000000
2445 Verifying Checksum ... OK
2447 => bootm 40100000 40200000
2448 ## Booting Linux kernel at 40100000 ...
2449 Image Name: 2.2.13 for initrd on TQM850L
2450 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2451 Data Size: 335725 Bytes = 327 kB = 0 MB
2452 Load Address: 00000000
2453 Entry Point: 0000000c
2454 Verifying Checksum ... OK
2455 Uncompressing Kernel Image ... OK
2456 ## Loading RAMDisk Image at 40200000 ...
2457 Image Name: Simple Ramdisk Image
2458 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2459 Data Size: 566530 Bytes = 553 kB = 0 MB
2460 Load Address: 00000000
2461 Entry Point: 00000000
2462 Verifying Checksum ... OK
2463 Loading Ramdisk ... OK
2464 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
2465 Boot arguments: root=/dev/ram
2466 time_init: decrementer frequency = 187500000/60
2467 Calibrating delay loop... 49.77 BogoMIPS
2469 RAMDISK: Compressed image found at block 0
2470 VFS: Mounted root (ext2 filesystem).
2474 More About U-Boot Image Types:
2475 ------------------------------
2477 U-Boot supports the following image types:
2479 "Standalone Programs" are directly runnable in the environment
2480 provided by U-Boot; it is expected that (if they behave
2481 well) you can continue to work in U-Boot after return from
2482 the Standalone Program.
2483 "OS Kernel Images" are usually images of some Embedded OS which
2484 will take over control completely. Usually these programs
2485 will install their own set of exception handlers, device
2486 drivers, set up the MMU, etc. - this means, that you cannot
2487 expect to re-enter U-Boot except by resetting the CPU.
2488 "RAMDisk Images" are more or less just data blocks, and their
2489 parameters (address, size) are passed to an OS kernel that is
2491 "Multi-File Images" contain several images, typically an OS
2492 (Linux) kernel image and one or more data images like
2493 RAMDisks. This construct is useful for instance when you want
2494 to boot over the network using BOOTP etc., where the boot
2495 server provides just a single image file, but you want to get
2496 for instance an OS kernel and a RAMDisk image.
2498 "Multi-File Images" start with a list of image sizes, each
2499 image size (in bytes) specified by an "uint32_t" in network
2500 byte order. This list is terminated by an "(uint32_t)0".
2501 Immediately after the terminating 0 follow the images, one by
2502 one, all aligned on "uint32_t" boundaries (size rounded up to
2503 a multiple of 4 bytes).
2505 "Firmware Images" are binary images containing firmware (like
2506 U-Boot or FPGA images) which usually will be programmed to
2509 "Script files" are command sequences that will be executed by
2510 U-Boot's command interpreter; this feature is especially
2511 useful when you configure U-Boot to use a real shell (hush)
2512 as command interpreter.
2518 One of the features of U-Boot is that you can dynamically load and
2519 run "standalone" applications, which can use some resources of
2520 U-Boot like console I/O functions or interrupt services.
2522 Two simple examples are included with the sources:
2527 'examples/hello_world.c' contains a small "Hello World" Demo
2528 application; it is automatically compiled when you build U-Boot.
2529 It's configured to run at address 0x00040004, so you can play with it
2533 ## Ready for S-Record download ...
2534 ~>examples/hello_world.srec
2535 1 2 3 4 5 6 7 8 9 10 11 ...
2536 [file transfer complete]
2538 ## Start Addr = 0x00040004
2540 => go 40004 Hello World! This is a test.
2541 ## Starting application at 0x00040004 ...
2552 Hit any key to exit ...
2554 ## Application terminated, rc = 0x0
2556 Another example, which demonstrates how to register a CPM interrupt
2557 handler with the U-Boot code, can be found in 'examples/timer.c'.
2558 Here, a CPM timer is set up to generate an interrupt every second.
2559 The interrupt service routine is trivial, just printing a '.'
2560 character, but this is just a demo program. The application can be
2561 controlled by the following keys:
2563 ? - print current values og the CPM Timer registers
2564 b - enable interrupts and start timer
2565 e - stop timer and disable interrupts
2566 q - quit application
2569 ## Ready for S-Record download ...
2570 ~>examples/timer.srec
2571 1 2 3 4 5 6 7 8 9 10 11 ...
2572 [file transfer complete]
2574 ## Start Addr = 0x00040004
2577 ## Starting application at 0x00040004 ...
2580 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2583 [q, b, e, ?] Set interval 1000000 us
2586 [q, b, e, ?] ........
2587 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2590 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2593 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2596 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2598 [q, b, e, ?] ...Stopping timer
2600 [q, b, e, ?] ## Application terminated, rc = 0x0
2607 Over time, many people have reported problems when trying to used the
2608 "minicom" terminal emulation program for serial download. I (wd)
2609 consider minicom to be broken, and recommend not to use it. Under
2610 Unix, I recommend to use C-Kermit for general purpose use (and
2611 especially for kermit binary protocol download ("loadb" command), and
2612 use "cu" for S-Record download ("loads" command).
2617 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2618 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2620 Building requires a cross environment; it is known to work on
2621 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2622 need gmake since the Makefiles are not compatible with BSD make).
2623 Note that the cross-powerpc package does not install include files;
2624 attempting to build U-Boot will fail because <machine/ansi.h> is
2625 missing. This file has to be installed and patched manually:
2627 # cd /usr/pkg/cross/powerpc-netbsd/include
2629 # ln -s powerpc machine
2630 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2631 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2633 Native builds *don't* work due to incompatibilities between native
2634 and U-Boot include files.
2636 Booting assumes that (the first part of) the image booted is a
2637 stage-2 loader which in turn loads and then invokes the kernel
2638 proper. Loader sources will eventually appear in the NetBSD source
2639 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2640 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2644 Implementation Internals:
2645 =========================
2647 The following is not intended to be a complete description of every
2648 implementation detail. However, it should help to understand the
2649 inner workings of U-Boot and make it easier to port it to custom
2653 Initial Stack, Global Data:
2654 ---------------------------
2656 The implementation of U-Boot is complicated by the fact that U-Boot
2657 starts running out of ROM (flash memory), usually without access to
2658 system RAM (because the memory controller is not initialized yet).
2659 This means that we don't have writable Data or BSS segments, and BSS
2660 is not initialized as zero. To be able to get a C environment working
2661 at all, we have to allocate at least a minimal stack. Implementation
2662 options for this are defined and restricted by the CPU used: Some CPU
2663 models provide on-chip memory (like the IMMR area on MPC8xx and
2664 MPC826x processors), on others (parts of) the data cache can be
2665 locked as (mis-) used as memory, etc.
2667 Chris Hallinan posted a good summy of these issues to the
2668 u-boot-users mailing list:
2670 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2671 From: "Chris Hallinan" <clh@net1plus.com>
2672 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2675 Correct me if I'm wrong, folks, but the way I understand it
2676 is this: Using DCACHE as initial RAM for Stack, etc, does not
2677 require any physical RAM backing up the cache. The cleverness
2678 is that the cache is being used as a temporary supply of
2679 necessary storage before the SDRAM controller is setup. It's
2680 beyond the scope of this list to expain the details, but you
2681 can see how this works by studying the cache architecture and
2682 operation in the architecture and processor-specific manuals.
2684 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2685 is another option for the system designer to use as an
2686 initial stack/ram area prior to SDRAM being available. Either
2687 option should work for you. Using CS 4 should be fine if your
2688 board designers haven't used it for something that would
2689 cause you grief during the initial boot! It is frequently not
2692 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2693 with your processor/board/system design. The default value
2694 you will find in any recent u-boot distribution in
2695 Walnut405.h should work for you. I'd set it to a value larger
2696 than your SDRAM module. If you have a 64MB SDRAM module, set
2697 it above 400_0000. Just make sure your board has no resources
2698 that are supposed to respond to that address! That code in
2699 start.S has been around a while and should work as is when
2700 you get the config right.
2705 It is essential to remember this, since it has some impact on the C
2706 code for the initialization procedures:
2708 * Initialized global data (data segment) is read-only. Do not attempt
2711 * Do not use any unitialized global data (or implicitely initialized
2712 as zero data - BSS segment) at all - this is undefined, initiali-
2713 zation is performed later (when relocationg to RAM).
2715 * Stack space is very limited. Avoid big data buffers or things like
2718 Having only the stack as writable memory limits means we cannot use
2719 normal global data to share information beween the code. But it
2720 turned out that the implementation of U-Boot can be greatly
2721 simplified by making a global data structure (gd_t) available to all
2722 functions. We could pass a pointer to this data as argument to _all_
2723 functions, but this would bloat the code. Instead we use a feature of
2724 the GCC compiler (Global Register Variables) to share the data: we
2725 place a pointer (gd) to the global data into a register which we
2726 reserve for this purpose.
2728 When chosing a register for such a purpose we are restricted by the
2729 relevant (E)ABI specifications for the current architecture, and by
2730 GCC's implementation.
2732 For PowerPC, the following registers have specific use:
2735 R3-R4: parameter passing and return values
2736 R5-R10: parameter passing
2737 R13: small data area pointer
2741 (U-Boot also uses R14 as internal GOT pointer.)
2743 ==> U-Boot will use R29 to hold a pointer to the global data
2745 Note: on PPC, we could use a static initializer (since the
2746 address of the global data structure is known at compile time),
2747 but it turned out that reserving a register results in somewhat
2748 smaller code - although the code savings are not that big (on
2749 average for all boards 752 bytes for the whole U-Boot image,
2750 624 text + 127 data).
2752 On ARM, the following registers are used:
2754 R0: function argument word/integer result
2755 R1-R3: function argument word
2757 R10: stack limit (used only if stack checking if enabled)
2758 R11: argument (frame) pointer
2759 R12: temporary workspace
2762 R15: program counter
2764 ==> U-Boot will use R8 to hold a pointer to the global data
2771 U-Boot runs in system state and uses physical addresses, i.e. the
2772 MMU is not used either for address mapping nor for memory protection.
2774 The available memory is mapped to fixed addresses using the memory
2775 controller. In this process, a contiguous block is formed for each
2776 memory type (Flash, SDRAM, SRAM), even when it consists of several
2777 physical memory banks.
2779 U-Boot is installed in the first 128 kB of the first Flash bank (on
2780 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2781 booting and sizing and initializing DRAM, the code relocates itself
2782 to the upper end of DRAM. Immediately below the U-Boot code some
2783 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2784 configuration setting]. Below that, a structure with global Board
2785 Info data is placed, followed by the stack (growing downward).
2787 Additionally, some exception handler code is copied to the low 8 kB
2788 of DRAM (0x00000000 ... 0x00001FFF).
2790 So a typical memory configuration with 16 MB of DRAM could look like
2793 0x0000 0000 Exception Vector code
2796 0x0000 2000 Free for Application Use
2802 0x00FB FF20 Monitor Stack (Growing downward)
2803 0x00FB FFAC Board Info Data and permanent copy of global data
2804 0x00FC 0000 Malloc Arena
2807 0x00FE 0000 RAM Copy of Monitor Code
2808 ... eventually: LCD or video framebuffer
2809 ... eventually: pRAM (Protected RAM - unchanged by reset)
2810 0x00FF FFFF [End of RAM]
2813 System Initialization:
2814 ----------------------
2816 In the reset configuration, U-Boot starts at the reset entry point
2817 (on most PowerPC systens at address 0x00000100). Because of the reset
2818 configuration for CS0# this is a mirror of the onboard Flash memory.
2819 To be able to re-map memory U-Boot then jumps to it's link address.
2820 To be able to implement the initialization code in C, a (small!)
2821 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2822 which provide such a feature like MPC8xx or MPC8260), or in a locked
2823 part of the data cache. After that, U-Boot initializes the CPU core,
2824 the caches and the SIU.
2826 Next, all (potentially) available memory banks are mapped using a
2827 preliminary mapping. For example, we put them on 512 MB boundaries
2828 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2829 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2830 programmed for SDRAM access. Using the temporary configuration, a
2831 simple memory test is run that determines the size of the SDRAM
2834 When there is more than one SDRAM bank, and the banks are of
2835 different size, the larger is mapped first. For equal size, the first
2836 bank (CS2#) is mapped first. The first mapping is always for address
2837 0x00000000, with any additional banks following immediately to create
2838 contiguous memory starting from 0.
2840 Then, the monitor installs itself at the upper end of the SDRAM area
2841 and allocates memory for use by malloc() and for the global Board
2842 Info data; also, the exception vector code is copied to the low RAM
2843 pages, and the final stack is set up.
2845 Only after this relocation will you have a "normal" C environment;
2846 until that you are restricted in several ways, mostly because you are
2847 running from ROM, and because the code will have to be relocated to a
2851 U-Boot Porting Guide:
2852 ----------------------
2854 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2858 int main (int argc, char *argv[])
2860 sighandler_t no_more_time;
2862 signal (SIGALRM, no_more_time);
2863 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2865 if (available_money > available_manpower) {
2866 pay consultant to port U-Boot;
2870 Download latest U-Boot source;
2872 Subscribe to u-boot-users mailing list;
2875 email ("Hi, I am new to U-Boot, how do I get started?");
2879 Read the README file in the top level directory;
2880 Read http://www.denx.de/re/DPLG.html
2881 Read the source, Luke;
2884 if (available_money > toLocalCurrency ($2500)) {
2887 Add a lot of aggravation and time;
2890 Create your own board support subdirectory;
2892 Create your own board config file;
2896 Add / modify source code;
2900 email ("Hi, I am having problems...");
2902 Send patch file to Wolfgang;
2907 void no_more_time (int sig)
2917 All contributions to U-Boot should conform to the Linux kernel
2918 coding style; see the file "Documentation/CodingStyle" in your Linux
2919 kernel source directory.
2921 Please note that U-Boot is implemented in C (and to some small parts
2922 in Assembler); no C++ is used, so please do not use C++ style
2923 comments (//) in your code.
2925 Submissions which do not conform to the standards may be returned
2926 with a request to reformat the changes.
2932 Since the number of patches for U-Boot is growing, we need to
2933 establish some rules. Submissions which do not conform to these rules
2934 may be rejected, even when they contain important and valuable stuff.
2937 When you send a patch, please include the following information with
2940 * For bug fixes: a description of the bug and how your patch fixes
2941 this bug. Please try to include a way of demonstrating that the
2942 patch actually fixes something.
2944 * For new features: a description of the feature and your
2947 * A CHANGELOG entry as plaintext (separate from the patch)
2949 * For major contributions, your entry to the CREDITS file
2951 * When you add support for a new board, don't forget to add this
2952 board to the MAKEALL script, too.
2954 * If your patch adds new configuration options, don't forget to
2955 document these in the README file.
2957 * The patch itself. If you are accessing the CVS repository use "cvs
2958 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
2959 version of diff does not support these options, then get the latest
2960 version of GNU diff.
2962 We accept patches as plain text, MIME attachments or as uuencoded
2967 * Before sending the patch, run the MAKEALL script on your patched
2968 source tree and make sure that no errors or warnings are reported
2969 for any of the boards.
2971 * Keep your modifications to the necessary minimum: A patch
2972 containing several unrelated changes or arbitrary reformats will be
2973 returned with a request to re-formatting / split it.
2975 * If you modify existing code, make sure that your new code does not
2976 add to the memory footprint of the code ;-) Small is beautiful!
2977 When adding new features, these should compile conditionally only
2978 (using #ifdef), and the resulting code with the new feature
2979 disabled must not need more memory than the old code without your
projects / platform / kernel / u-boot.git / blob