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/arm925t Files specific to ARM 925 CPUs
144 - cpu/mpc5xx Files specific to Motorola MPC5xx CPUs
145 - cpu/mpc8xx Files specific to Motorola MPC8xx CPUs
146 - cpu/mpc824x Files specific to Motorola MPC824x CPUs
147 - cpu/mpc8260 Files specific to Motorola MPC8260 CPU
148 - cpu/ppc4xx Files specific to IBM 4xx CPUs
151 - board/LEOX/ Files specific to boards manufactured by The LEOX team
152 - board/LEOX/elpt860 Files specific to ELPT860 boards
154 Files specific to RPXClassic boards
155 - board/RPXlite Files specific to RPXlite boards
156 - board/at91rm9200dk Files specific to AT91RM9200DK boards
157 - board/c2mon Files specific to c2mon boards
158 - board/cmi Files specific to cmi boards
159 - board/cogent Files specific to Cogent boards
160 (need further configuration)
161 Files specific to CPCIISER4 boards
162 - board/cpu86 Files specific to CPU86 boards
163 - board/cray/ Files specific to boards manufactured by Cray
164 - board/cray/L1 Files specific to L1 boards
165 - board/cu824 Files specific to CU824 boards
166 - board/ebony Files specific to IBM Ebony board
167 - board/eric Files specific to ERIC boards
168 - board/esd/ Files specific to boards manufactured by ESD
169 - board/esd/adciop Files specific to ADCIOP boards
170 - board/esd/ar405 Files specific to AR405 boards
171 - board/esd/canbt Files specific to CANBT boards
172 - board/esd/cpci405 Files specific to CPCI405 boards
173 - board/esd/cpciiser4 Files specific to CPCIISER4 boards
174 - board/esd/common Common files for ESD boards
175 - board/esd/dasa_sim Files specific to DASA_SIM boards
176 - board/esd/du405 Files specific to DU405 boards
177 - board/esd/ocrtc Files specific to OCRTC boards
178 - board/esd/pci405 Files specific to PCI405 boards
180 Files specific to ESTEEM192E boards
181 - board/etx094 Files specific to ETX_094 boards
183 Files specific to EVB64260 boards
184 - board/fads Files specific to FADS boards
185 - board/flagadm Files specific to FLAGADM boards
186 - board/gen860t Files specific to GEN860T and GEN860T_SC boards
187 - board/genietv Files specific to GENIETV boards
188 - board/gth Files specific to GTH boards
189 - board/hermes Files specific to HERMES boards
190 - board/hymod Files specific to HYMOD boards
191 - board/icu862 Files specific to ICU862 boards
192 - board/ip860 Files specific to IP860 boards
194 Files specific to Interphase4539 boards
195 - board/ivm Files specific to IVMS8/IVML24 boards
196 - board/lantec Files specific to LANTEC boards
197 - board/lwmon Files specific to LWMON boards
198 - board/mbx8xx Files specific to MBX boards
200 Files specific to MPC8260ADS and PQ2FADS-ZU boards
201 - board/mpl/ Files specific to boards manufactured by MPL
202 - board/mpl/common Common files for MPL boards
203 - board/mpl/pip405 Files specific to PIP405 boards
204 - board/mpl/mip405 Files specific to MIP405 boards
205 - board/musenki Files specific to MUSEKNI boards
206 - board/mvs1 Files specific to MVS1 boards
207 - board/nx823 Files specific to NX823 boards
208 - board/oxc Files specific to OXC boards
210 Files specific to OMAP 1510 Innovator boards
211 - board/pcippc2 Files specific to PCIPPC2/PCIPPC6 boards
212 - board/pm826 Files specific to PM826 boards
214 Files specific to PPMC8260 boards
216 Files specific to RPXsuper boards
218 Files specific to RSDproto boards
220 Files specific to Sandpoint boards
221 - board/sbc8260 Files specific to SBC8260 boards
222 - board/sacsng Files specific to SACSng boards
223 - board/siemens Files specific to boards manufactured by Siemens AG
224 - board/siemens/CCM Files specific to CCM boards
225 - board/siemens/IAD210 Files specific to IAD210 boards
226 - board/siemens/SCM Files specific to SCM boards
227 - board/siemens/pcu_e Files specific to PCU_E boards
228 - board/sixnet Files specific to SIXNET boards
229 - board/spd8xx Files specific to SPD8xxTS boards
230 - board/tqm8260 Files specific to TQM8260 boards
231 - board/tqm8xx Files specific to TQM8xxL boards
232 - board/w7o Files specific to W7O boards
234 Files specific to Walnut405 boards
235 - board/westel/ Files specific to boards manufactured by Westel Wireless
236 - board/westel/amx860 Files specific to AMX860 boards
237 - board/utx8245 Files specific to UTX8245 boards
239 Software Configuration:
240 =======================
242 Configuration is usually done using C preprocessor defines; the
243 rationale behind that is to avoid dead code whenever possible.
245 There are two classes of configuration variables:
247 * Configuration _OPTIONS_:
248 These are selectable by the user and have names beginning with
251 * Configuration _SETTINGS_:
252 These depend on the hardware etc. and should not be meddled with if
253 you don't know what you're doing; they have names beginning with
256 Later we will add a configuration tool - probably similar to or even
257 identical to what's used for the Linux kernel. Right now, we have to
258 do the configuration by hand, which means creating some symbolic
259 links and editing some configuration files. We use the TQM8xxL boards
263 Selection of Processor Architecture and Board Type:
264 ---------------------------------------------------
266 For all supported boards there are ready-to-use default
267 configurations available; just type "make <board_name>_config".
269 Example: For a TQM823L module type:
274 For the Cogent platform, you need to specify the cpu type as well;
275 e.g. "make cogent_mpc8xx_config". And also configure the cogent
276 directory according to the instructions in cogent/README.
279 Configuration Options:
280 ----------------------
282 Configuration depends on the combination of board and CPU type; all
283 such information is kept in a configuration file
284 "include/configs/<board_name>.h".
286 Example: For a TQM823L module, all configuration settings are in
287 "include/configs/TQM823L.h".
290 Many of the options are named exactly as the corresponding Linux
291 kernel configuration options. The intention is to make it easier to
292 build a config tool - later.
295 The following options need to be configured:
297 - CPU Type: Define exactly one of
301 CONFIG_MPC823, CONFIG_MPC850, CONFIG_MPC855, CONFIG_MPC860
303 or CONFIG_MPC824X, CONFIG_MPC8260
317 - Board Type: Define exactly one of
319 PowerPC based boards:
320 ---------------------
322 CONFIG_ADCIOP, CONFIG_ICU862 CONFIG_RPXsuper,
323 CONFIG_ADS860, CONFIG_IP860, CONFIG_SM850,
324 CONFIG_AMX860, CONFIG_IPHASE4539, CONFIG_SPD823TS,
325 CONFIG_AR405, CONFIG_IVML24, CONFIG_SXNI855T,
326 CONFIG_BAB7xx, CONFIG_IVML24_128, CONFIG_Sandpoint8240,
327 CONFIG_CANBT, CONFIG_IVML24_256, CONFIG_Sandpoint8245,
328 CONFIG_CCM, CONFIG_IVMS8, CONFIG_TQM823L,
329 CONFIG_CPCI405, CONFIG_IVMS8_128, CONFIG_TQM850L,
330 CONFIG_CPCI4052, CONFIG_IVMS8_256, CONFIG_TQM855L,
331 CONFIG_CPCIISER4, CONFIG_LANTEC, CONFIG_TQM860L,
332 CONFIG_CPU86, CONFIG_MBX, CONFIG_TQM8260,
333 CONFIG_CRAYL1, CONFIG_MBX860T, CONFIG_TTTech,
334 CONFIG_CU824, CONFIG_MHPC, CONFIG_UTX8245,
335 CONFIG_DASA_SIM, CONFIG_MIP405, CONFIG_W7OLMC,
336 CONFIG_DU405, CONFIG_MOUSSE, CONFIG_W7OLMG,
337 CONFIG_ELPPC, CONFIG_MPC8260ADS, CONFIG_WALNUT405,
338 CONFIG_ERIC, CONFIG_MUSENKI, CONFIG_ZUMA,
339 CONFIG_ESTEEM192E, CONFIG_MVS1, CONFIG_c2mon,
340 CONFIG_ETX094, CONFIG_NX823, CONFIG_cogent_mpc8260,
341 CONFIG_EVB64260, CONFIG_OCRTC, CONFIG_cogent_mpc8xx,
342 CONFIG_FADS823, CONFIG_ORSG, CONFIG_ep8260,
343 CONFIG_FADS850SAR, CONFIG_OXC, CONFIG_gw8260,
344 CONFIG_FADS860T, CONFIG_PCI405, CONFIG_hermes,
345 CONFIG_FLAGADM, CONFIG_PCIPPC2, CONFIG_hymod,
346 CONFIG_FPS850L, CONFIG_PCIPPC6, CONFIG_lwmon,
347 CONFIG_GEN860T, CONFIG_PIP405, CONFIG_pcu_e,
348 CONFIG_GENIETV, CONFIG_PM826, CONFIG_ppmc8260,
349 CONFIG_GTH, CONFIG_RPXClassic, CONFIG_rsdproto,
350 CONFIG_IAD210, CONFIG_RPXlite, CONFIG_sbc8260,
351 CONFIG_EBONY, CONFIG_sacsng, CONFIG_FPS860L,
352 CONFIG_V37, CONFIG_ELPT860, CONFIG_CMI,
353 CONFIG_NETVIA, CONFIG_RBC823
358 CONFIG_HHP_CRADLE, CONFIG_DNP1110, CONFIG_EP7312,
359 CONFIG_IMPA7, CONFIG_LART, CONFIG_LUBBOCK,
360 CONFIG_INNOVATOROMAP1510,
361 CONFIG_SHANNON, CONFIG_SMDK2400, CONFIG_SMDK2410,
362 CONFIG_TRAB, CONFIG_AT91RM9200DK
365 - CPU Module Type: (if CONFIG_COGENT is defined)
366 Define exactly one of
368 --- FIXME --- not tested yet:
369 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
370 CONFIG_CMA287_23, CONFIG_CMA287_50
372 - Motherboard Type: (if CONFIG_COGENT is defined)
373 Define exactly one of
374 CONFIG_CMA101, CONFIG_CMA102
376 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
377 Define one or more of
380 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
381 Define one or more of
382 CONFIG_LCD_HEARTBEAT - update a character position on
383 the lcd display every second with
386 - Board flavour: (if CONFIG_MPC8260ADS is defined)
389 CFG_8260ADS - original MPC8260ADS
390 CFG_8266ADS - MPC8266ADS (untested)
391 CFG_PQ2FADS - PQ2FADS-ZU
394 - MPC824X Family Member (if CONFIG_MPC824X is defined)
395 Define exactly one of
396 CONFIG_MPC8240, CONFIG_MPC8245
398 - 8xx CPU Options: (if using an 8xx cpu)
399 Define one or more of
400 CONFIG_8xx_GCLK_FREQ - if get_gclk_freq() can not work e.g.
401 no 32KHz reference PIT/RTC clock
406 U-Boot stores all clock information in Hz
407 internally. For binary compatibility with older Linux
408 kernels (which expect the clocks passed in the
409 bd_info data to be in MHz) the environment variable
410 "clocks_in_mhz" can be defined so that U-Boot
411 converts clock data to MHZ before passing it to the
414 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
415 "clocks_in_mhz=1" is automatically included in the
419 Depending on board, define exactly one serial port
420 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
421 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
422 console by defining CONFIG_8xx_CONS_NONE
424 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
425 port routines must be defined elsewhere
426 (i.e. serial_init(), serial_getc(), ...)
429 Enables console device for a color framebuffer. Needs following
430 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
431 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
433 VIDEO_HW_RECTFILL graphic chip supports
436 VIDEO_HW_BITBLT graphic chip supports
437 bit-blit (cf. smiLynxEM)
438 VIDEO_VISIBLE_COLS visible pixel columns
440 VIDEO_VISIBLE_ROWS visible pixel rows
441 VIDEO_PIXEL_SIZE bytes per pixel
442 VIDEO_DATA_FORMAT graphic data format
443 (0-5, cf. cfb_console.c)
444 VIDEO_FB_ADRS framebuffer address
445 VIDEO_KBD_INIT_FCT keyboard int fct
446 (i.e. i8042_kbd_init())
447 VIDEO_TSTC_FCT test char fct
449 VIDEO_GETC_FCT get char fct
451 CONFIG_CONSOLE_CURSOR cursor drawing on/off
452 (requires blink timer
454 CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
455 CONFIG_CONSOLE_TIME display time/date info in
457 (requires CFG_CMD_DATE)
458 CONFIG_VIDEO_LOGO display Linux logo in
460 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
461 linux_logo.h for logo.
462 Requires CONFIG_VIDEO_LOGO
463 CONFIG_CONSOLE_EXTRA_INFO
464 addional board info beside
467 When CONFIG_CFB_CONSOLE is defined, video console is
468 default i/o. Serial console can be forced with
469 environment 'console=serial'.
472 CONFIG_BAUDRATE - in bps
473 Select one of the baudrates listed in
474 CFG_BAUDRATE_TABLE, see below.
476 - Interrupt driven serial port input:
477 CONFIG_SERIAL_SOFTWARE_FIFO
480 Use an interrupt handler for receiving data on the
481 serial port. It also enables using hardware handshake
482 (RTS/CTS) and UART's built-in FIFO. Set the number of
483 bytes the interrupt driven input buffer should have.
485 Set to 0 to disable this feature (this is the default).
486 This will also disable hardware handshake.
488 - Console UART Number:
492 If defined internal UART1 (and not UART0) is used
493 as default U-Boot console.
495 - Boot Delay: CONFIG_BOOTDELAY - in seconds
496 Delay before automatically booting the default image;
497 set to -1 to disable autoboot.
499 See doc/README.autoboot for these options that
500 work with CONFIG_BOOTDELAY. None are required.
501 CONFIG_BOOT_RETRY_TIME
502 CONFIG_BOOT_RETRY_MIN
503 CONFIG_AUTOBOOT_KEYED
504 CONFIG_AUTOBOOT_PROMPT
505 CONFIG_AUTOBOOT_DELAY_STR
506 CONFIG_AUTOBOOT_STOP_STR
507 CONFIG_AUTOBOOT_DELAY_STR2
508 CONFIG_AUTOBOOT_STOP_STR2
509 CONFIG_ZERO_BOOTDELAY_CHECK
510 CONFIG_RESET_TO_RETRY
514 Only needed when CONFIG_BOOTDELAY is enabled;
515 define a command string that is automatically executed
516 when no character is read on the console interface
517 within "Boot Delay" after reset.
520 This can be used to pass arguments to the bootm
521 command. The value of CONFIG_BOOTARGS goes into the
522 environment value "bootargs".
524 CONFIG_RAMBOOT and CONFIG_NFSBOOT
525 The value of these goes into the environment as
526 "ramboot" and "nfsboot" respectively, and can be used
527 as a convenience, when switching between booting from
533 When this option is #defined, the existence of the
534 environment variable "preboot" will be checked
535 immediately before starting the CONFIG_BOOTDELAY
536 countdown and/or running the auto-boot command resp.
537 entering interactive mode.
539 This feature is especially useful when "preboot" is
540 automatically generated or modified. For an example
541 see the LWMON board specific code: here "preboot" is
542 modified when the user holds down a certain
543 combination of keys on the (special) keyboard when
546 - Serial Download Echo Mode:
548 If defined to 1, all characters received during a
549 serial download (using the "loads" command) are
550 echoed back. This might be needed by some terminal
551 emulations (like "cu"), but may as well just take
552 time on others. This setting #define's the initial
553 value of the "loads_echo" environment variable.
555 - Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
557 Select one of the baudrates listed in
558 CFG_BAUDRATE_TABLE, see below.
562 Most monitor functions can be selected (or
563 de-selected) by adjusting the definition of
564 CONFIG_COMMANDS; to select individual functions,
565 #define CONFIG_COMMANDS by "OR"ing any of the
568 #define enables commands:
569 -------------------------
570 CFG_CMD_ASKENV * ask for env variable
572 CFG_CMD_BEDBUG Include BedBug Debugger
574 CFG_CMD_CACHE icache, dcache
575 CFG_CMD_CONSOLE coninfo
576 CFG_CMD_DATE * support for RTC, date/time...
577 CFG_CMD_DHCP DHCP support
578 CFG_CMD_ECHO * echo arguments
579 CFG_CMD_EEPROM * EEPROM read/write support
580 CFG_CMD_ELF bootelf, bootvx
582 CFG_CMD_FDC * Floppy Disk Support
583 CFG_CMD_FAT FAT partition support
584 CFG_CMD_FDOS * Dos diskette Support
585 CFG_CMD_FLASH flinfo, erase, protect
586 CFG_CMD_FPGA FPGA device initialization support
587 CFG_CMD_I2C * I2C serial bus support
588 CFG_CMD_IDE * IDE harddisk support
590 CFG_CMD_IMMAP * IMMR dump support
591 CFG_CMD_IRQ * irqinfo
595 CFG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
597 CFG_CMD_MMC MMC memory mapped support
598 CFG_CMD_MII MII utility commands
599 CFG_CMD_NET bootp, tftpboot, rarpboot
600 CFG_CMD_PCI * pciinfo
601 CFG_CMD_PCMCIA * PCMCIA support
602 CFG_CMD_REGINFO * Register dump
603 CFG_CMD_RUN run command in env variable
604 CFG_CMD_SCSI * SCSI Support
605 CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
606 CFG_CMD_SPI * SPI serial bus support
607 CFG_CMD_USB * USB support
608 CFG_CMD_BSP * Board SPecific functions
609 -----------------------------------------------
612 CFG_CMD_DFL Default configuration; at the moment
613 this is includes all commands, except
614 the ones marked with "*" in the list
617 If you don't define CONFIG_COMMANDS it defaults to
618 CFG_CMD_DFL in include/cmd_confdefs.h. A board can
619 override the default settings in the respective
622 EXAMPLE: If you want all functions except of network
623 support you can write:
625 #define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)
628 Note: Don't enable the "icache" and "dcache" commands
629 (configuration option CFG_CMD_CACHE) unless you know
630 what you (and your U-Boot users) are doing. Data
631 cache cannot be enabled on systems like the 8xx or
632 8260 (where accesses to the IMMR region must be
633 uncached), and it cannot be disabled on all other
634 systems where we (mis-) use the data cache to hold an
635 initial stack and some data.
638 XXX - this list needs to get updated!
642 If this variable is defined, it enables watchdog
643 support. There must support in the platform specific
644 code for a watchdog. For the 8xx and 8260 CPUs, the
645 SIU Watchdog feature is enabled in the SYPCR
649 CONFIG_VERSION_VARIABLE
650 If this variable is defined, an environment variable
651 named "ver" is created by U-Boot showing the U-Boot
652 version as printed by the "version" command.
653 This variable is readonly.
657 When CFG_CMD_DATE is selected, the type of the RTC
658 has to be selected, too. Define exactly one of the
661 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
662 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
663 CONFIG_RTC_MC146818 - use MC146818 RTC
664 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
665 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
666 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
667 CONFIG_RTC_DS164x - use Dallas DS164x RTC
669 Note that if the RTC uses I2C, then the I2C interface
670 must also be configured. See I2C Support, below.
674 When CONFIG_TIMESTAMP is selected, the timestamp
675 (date and time) of an image is printed by image
676 commands like bootm or iminfo. This option is
677 automatically enabled when you select CFG_CMD_DATE .
680 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
681 and/or CONFIG_ISO_PARTITION
683 If IDE or SCSI support is enabled (CFG_CMD_IDE or
684 CFG_CMD_SCSI) you must configure support for at least
685 one partition type as well.
688 CONFIG_IDE_RESET_ROUTINE
690 Set this to define that instead of a reset Pin, the
691 routine ide_set_reset(int idereset) will be used.
696 Set this to enable ATAPI support.
699 At the moment only there is only support for the
700 SYM53C8XX SCSI controller; define
701 CONFIG_SCSI_SYM53C8XX to enable it.
703 CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and
704 CFG_SCSI_MAX_DEVICE [CFG_SCSI_MAX_SCSI_ID *
705 CFG_SCSI_MAX_LUN] can be adjusted to define the
706 maximum numbers of LUNs, SCSI ID's and target
708 CFG_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
710 - NETWORK Support (PCI):
712 Support for Intel 8254x gigabit chips.
715 Support for Intel 82557/82559/82559ER chips.
716 Optional CONFIG_EEPRO100_SROM_WRITE enables eeprom
717 write routine for first time initialisation.
720 Support for Digital 2114x chips.
721 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
722 modem chip initialisation (KS8761/QS6611).
725 Support for National dp83815 chips.
728 Support for National dp8382[01] gigabit chips.
730 - NETWORK Support (other):
732 CONFIG_DRIVER_LAN91C96
733 Support for SMSC's LAN91C96 chips.
736 Define this to hold the physical address
737 of the LAN91C96's I/O space
739 CONFIG_LAN91C96_USE_32_BIT
740 Define this to enable 32 bit addressing
743 At the moment only the UHCI host controller is
744 supported (PIP405, MIP405); define
745 CONFIG_USB_UHCI to enable it.
746 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
747 end define CONFIG_USB_STORAGE to enable the USB
750 Supported are USB Keyboards and USB Floppy drives
754 The MMC controller on the Intel PXA is supported. To
755 enable this define CONFIG_MMC. The MMC can be
756 accessed from the boot prompt by mapping the device
757 to physical memory similar to flash. Command line is
758 enabled with CFG_CMD_MMC. The MMC driver also works with
759 the FAT fs. This is enabled with CFG_CMD_FAT.
764 Define this to enable standard (PC-Style) keyboard
768 Standard PC keyboard driver with US (is default) and
769 GERMAN key layout (switch via environment 'keymap=de') support.
770 Export function i8042_kbd_init, i8042_tstc and i8042_getc
771 for cfb_console. Supports cursor blinking.
776 Define this to enable video support (for output to
781 Enable Chips & Technologies 69000 Video chip
783 CONFIG_VIDEO_SMI_LYNXEM
784 Enable Silicon Motion SMI 712/710/810 Video chip
785 Videomode are selected via environment 'videomode' with
786 standard LiLo mode numbers.
787 Following modes are supported (* is default):
789 800x600 1024x768 1280x1024
790 256 (8bit) 303* 305 307
791 65536 (16bit) 314 317 31a
792 16,7 Mill (24bit) 315 318 31b
793 (i.e. setenv videomode 317; saveenv; reset;)
795 CONFIG_VIDEO_SED13806
796 Enable Epson SED13806 driver. This driver supports 8bpp
797 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
798 or CONFIG_VIDEO_SED13806_16BPP
803 Define this to enable a custom keyboard support.
804 This simply calls drv_keyboard_init() which must be
805 defined in your board-specific files.
806 The only board using this so far is RBC823.
808 - LCD Support: CONFIG_LCD
810 Define this to enable LCD support (for output to LCD
811 display); also select one of the supported displays
812 by defining one of these:
814 CONFIG_NEC_NL6648AC33:
816 NEC NL6648AC33-18. Active, color, single scan.
818 CONFIG_NEC_NL6648BC20
820 NEC NL6648BC20-08. 6.5", 640x480.
821 Active, color, single scan.
825 Sharp 320x240. Active, color, single scan.
826 It isn't 16x9, and I am not sure what it is.
828 CONFIG_SHARP_LQ64D341
830 Sharp LQ64D341 display, 640x480.
831 Active, color, single scan.
835 HLD1045 display, 640x480.
836 Active, color, single scan.
840 Optrex CBL50840-2 NF-FW 99 22 M5
842 Hitachi LMG6912RPFC-00T
846 320x240. Black & white.
848 Normally display is black on white background; define
849 CFG_WHITE_ON_BLACK to get it inverted.
851 - Spash Screen Support: CONFIG_SPLASH_SCREEN
853 If this option is set, the environment is checked for
854 a variable "splashimage". If found, the usual display
855 of logo, copyright and system information on the LCD
856 is supressed and the BMP image at the address
857 specified in "splashimage" is loaded instead. The
858 console is redirected to the "nulldev", too. This
859 allows for a "silent" boot where a splash screen is
860 loaded very quickly after power-on.
868 Define a default value for ethernet address to use
869 for the respective ethernet interface, in case this
870 is not determined automatically.
875 Define a default value for the IP address to use for
876 the default ethernet interface, in case this is not
877 determined through e.g. bootp.
882 Defines a default value for theIP address of a TFTP
883 server to contact when using the "tftboot" command.
885 - BOOTP Recovery Mode:
886 CONFIG_BOOTP_RANDOM_DELAY
888 If you have many targets in a network that try to
889 boot using BOOTP, you may want to avoid that all
890 systems send out BOOTP requests at precisely the same
891 moment (which would happen for instance at recovery
892 from a power failure, when all systems will try to
893 boot, thus flooding the BOOTP server. Defining
894 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
895 inserted before sending out BOOTP requests. The
896 following delays are insterted then:
898 1st BOOTP request: delay 0 ... 1 sec
899 2nd BOOTP request: delay 0 ... 2 sec
900 3rd BOOTP request: delay 0 ... 4 sec
902 BOOTP requests: delay 0 ... 8 sec
904 - DHCP Advanced Options:
907 You can fine tune the DHCP functionality by adding
908 these flags to the CONFIG_BOOTP_MASK define:
910 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
911 serverip from a DHCP server, it is possible that more
912 than one DNS serverip is offered to the client.
913 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
914 serverip will be stored in the additional environment
915 variable "dnsip2". The first DNS serverip is always
916 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
917 is added to the CONFIG_BOOTP_MASK.
919 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
920 to do a dynamic update of a DNS server. To do this, they
921 need the hostname of the DHCP requester.
922 If CONFIG_BOOP_SEND_HOSTNAME is added to the
923 CONFIG_BOOTP_MASK, the content of the "hostname"
924 environment variable is passed as option 12 to
927 - Status LED: CONFIG_STATUS_LED
929 Several configurations allow to display the current
930 status using a LED. For instance, the LED will blink
931 fast while running U-Boot code, stop blinking as
932 soon as a reply to a BOOTP request was received, and
933 start blinking slow once the Linux kernel is running
934 (supported by a status LED driver in the Linux
935 kernel). Defining CONFIG_STATUS_LED enables this
938 - CAN Support: CONFIG_CAN_DRIVER
940 Defining CONFIG_CAN_DRIVER enables CAN driver support
941 on those systems that support this (optional)
942 feature, like the TQM8xxL modules.
944 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
946 These enable I2C serial bus commands. Defining either of
947 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
948 include the appropriate I2C driver for the selected cpu.
950 This will allow you to use i2c commands at the u-boot
951 command line (as long as you set CFG_CMD_I2C in
952 CONFIG_COMMANDS) and communicate with i2c based realtime
953 clock chips. See common/cmd_i2c.c for a description of the
954 command line interface.
956 CONFIG_HARD_I2C selects the CPM hardware driver for I2C.
958 CONFIG_SOFT_I2C configures u-boot to use a software (aka
959 bit-banging) driver instead of CPM or similar hardware
962 There are several other quantities that must also be
963 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
965 In both cases you will need to define CFG_I2C_SPEED
966 to be the frequency (in Hz) at which you wish your i2c bus
967 to run and CFG_I2C_SLAVE to be the address of this node (ie
968 the cpu's i2c node address).
970 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
971 sets the cpu up as a master node and so its address should
972 therefore be cleared to 0 (See, eg, MPC823e User's Manual
973 p.16-473). So, set CFG_I2C_SLAVE to 0.
975 That's all that's required for CONFIG_HARD_I2C.
977 If you use the software i2c interface (CONFIG_SOFT_I2C)
978 then the following macros need to be defined (examples are
979 from include/configs/lwmon.h):
983 (Optional). Any commands necessary to enable the I2C
984 controller or configure ports.
986 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
990 (Only for MPC8260 CPU). The I/O port to use (the code
991 assumes both bits are on the same port). Valid values
992 are 0..3 for ports A..D.
996 The code necessary to make the I2C data line active
997 (driven). If the data line is open collector, this
1000 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1004 The code necessary to make the I2C data line tri-stated
1005 (inactive). If the data line is open collector, this
1008 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1012 Code that returns TRUE if the I2C data line is high,
1015 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1019 If <bit> is TRUE, sets the I2C data line high. If it
1020 is FALSE, it clears it (low).
1022 eg: #define I2C_SDA(bit) \
1023 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1024 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1028 If <bit> is TRUE, sets the I2C clock line high. If it
1029 is FALSE, it clears it (low).
1031 eg: #define I2C_SCL(bit) \
1032 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1033 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1037 This delay is invoked four times per clock cycle so this
1038 controls the rate of data transfer. The data rate thus
1039 is 1 / (I2C_DELAY * 4). Often defined to be something
1042 #define I2C_DELAY udelay(2)
1046 When a board is reset during an i2c bus transfer
1047 chips might think that the current transfer is still
1048 in progress. On some boards it is possible to access
1049 the i2c SCLK line directly, either by using the
1050 processor pin as a GPIO or by having a second pin
1051 connected to the bus. If this option is defined a
1052 custom i2c_init_board() routine in boards/xxx/board.c
1053 is run early in the boot sequence.
1055 - SPI Support: CONFIG_SPI
1057 Enables SPI driver (so far only tested with
1058 SPI EEPROM, also an instance works with Crystal A/D and
1059 D/As on the SACSng board)
1063 Enables extended (16-bit) SPI EEPROM addressing.
1064 (symmetrical to CONFIG_I2C_X)
1068 Enables a software (bit-bang) SPI driver rather than
1069 using hardware support. This is a general purpose
1070 driver that only requires three general I/O port pins
1071 (two outputs, one input) to function. If this is
1072 defined, the board configuration must define several
1073 SPI configuration items (port pins to use, etc). For
1074 an example, see include/configs/sacsng.h.
1076 - FPGA Support: CONFIG_FPGA_COUNT
1078 Specify the number of FPGA devices to support.
1082 Used to specify the types of FPGA devices. For
1084 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1086 CFG_FPGA_PROG_FEEDBACK
1088 Enable printing of hash marks during FPGA
1093 Enable checks on FPGA configuration interface busy
1094 status by the configuration function. This option
1095 will require a board or device specific function to
1100 If defined, a function that provides delays in the
1101 FPGA configuration driver.
1103 CFG_FPGA_CHECK_CTRLC
1105 Allow Control-C to interrupt FPGA configuration
1107 CFG_FPGA_CHECK_ERROR
1109 Check for configuration errors during FPGA bitfile
1110 loading. For example, abort during Virtex II
1111 configuration if the INIT_B line goes low (which
1112 indicated a CRC error).
1116 Maximum time to wait for the INIT_B line to deassert
1117 after PROB_B has been deasserted during a Virtex II
1118 FPGA configuration sequence. The default time is 500 mS.
1122 Maximum time to wait for BUSY to deassert during
1123 Virtex II FPGA configuration. The default is 5 mS.
1125 CFG_FPGA_WAIT_CONFIG
1127 Time to wait after FPGA configuration. The default is
1130 - FPGA Support: CONFIG_FPGA_COUNT
1132 Specify the number of FPGA devices to support.
1136 Used to specify the types of FPGA devices. For example,
1137 #define CONFIG_FPGA CFG_XILINX_VIRTEX2
1139 CFG_FPGA_PROG_FEEDBACK
1141 Enable printing of hash marks during FPGA configuration.
1145 Enable checks on FPGA configuration interface busy
1146 status by the configuration function. This option
1147 will require a board or device specific function to
1152 If defined, a function that provides delays in the FPGA
1153 configuration driver.
1155 CFG_FPGA_CHECK_CTRLC
1156 Allow Control-C to interrupt FPGA configuration
1158 CFG_FPGA_CHECK_ERROR
1160 Check for configuration errors during FPGA bitfile
1161 loading. For example, abort during Virtex II
1162 configuration if the INIT_B line goes low (which
1163 indicated a CRC error).
1167 Maximum time to wait for the INIT_B line to deassert
1168 after PROB_B has been deasserted during a Virtex II
1169 FPGA configuration sequence. The default time is 500
1174 Maximum time to wait for BUSY to deassert during
1175 Virtex II FPGA configuration. The default is 5 mS.
1177 CFG_FPGA_WAIT_CONFIG
1179 Time to wait after FPGA configuration. The default is
1182 - Configuration Management:
1185 If defined, this string will be added to the U-Boot
1186 version information (U_BOOT_VERSION)
1188 - Vendor Parameter Protection:
1190 U-Boot considers the values of the environment
1191 variables "serial#" (Board Serial Number) and
1192 "ethaddr" (Ethernet Address) to bb parameters that
1193 are set once by the board vendor / manufacturer, and
1194 protects these variables from casual modification by
1195 the user. Once set, these variables are read-only,
1196 and write or delete attempts are rejected. You can
1197 change this behviour:
1199 If CONFIG_ENV_OVERWRITE is #defined in your config
1200 file, the write protection for vendor parameters is
1201 completely disabled. Anybody can change or delete
1204 Alternatively, if you #define _both_ CONFIG_ETHADDR
1205 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1206 ethernet address is installed in the environment,
1207 which can be changed exactly ONCE by the user. [The
1208 serial# is unaffected by this, i. e. it remains
1214 Define this variable to enable the reservation of
1215 "protected RAM", i. e. RAM which is not overwritten
1216 by U-Boot. Define CONFIG_PRAM to hold the number of
1217 kB you want to reserve for pRAM. You can overwrite
1218 this default value by defining an environment
1219 variable "pram" to the number of kB you want to
1220 reserve. Note that the board info structure will
1221 still show the full amount of RAM. If pRAM is
1222 reserved, a new environment variable "mem" will
1223 automatically be defined to hold the amount of
1224 remaining RAM in a form that can be passed as boot
1225 argument to Linux, for instance like that:
1227 setenv bootargs ... mem=\$(mem)
1230 This way you can tell Linux not to use this memory,
1231 either, which results in a memory region that will
1232 not be affected by reboots.
1234 *WARNING* If your board configuration uses automatic
1235 detection of the RAM size, you must make sure that
1236 this memory test is non-destructive. So far, the
1237 following board configurations are known to be
1240 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1241 HERMES, IP860, RPXlite, LWMON, LANTEC,
1242 PCU_E, FLAGADM, TQM8260
1247 Define this variable to stop the system in case of a
1248 fatal error, so that you have to reset it manually.
1249 This is probably NOT a good idea for an embedded
1250 system where you want to system to reboot
1251 automatically as fast as possible, but it may be
1252 useful during development since you can try to debug
1253 the conditions that lead to the situation.
1255 CONFIG_NET_RETRY_COUNT
1257 This variable defines the number of retries for
1258 network operations like ARP, RARP, TFTP, or BOOTP
1259 before giving up the operation. If not defined, a
1260 default value of 5 is used.
1262 - Command Interpreter:
1265 Define this variable to enable the "hush" shell (from
1266 Busybox) as command line interpreter, thus enabling
1267 powerful command line syntax like
1268 if...then...else...fi conditionals or `&&' and '||'
1269 constructs ("shell scripts").
1271 If undefined, you get the old, much simpler behaviour
1272 with a somewhat smaller memory footprint.
1277 This defines the secondary prompt string, which is
1278 printed when the command interpreter needs more input
1279 to complete a command. Usually "> ".
1283 In the current implementation, the local variables
1284 space and global environment variables space are
1285 separated. Local variables are those you define by
1286 simply typing `name=value'. To access a local
1287 variable later on, you have write `$name' or
1288 `${name}'; to execute the contents of a variable
1289 directly type `$name' at the command prompt.
1291 Global environment variables are those you use
1292 setenv/printenv to work with. To run a command stored
1293 in such a variable, you need to use the run command,
1294 and you must not use the '$' sign to access them.
1296 To store commands and special characters in a
1297 variable, please use double quotation marks
1298 surrounding the whole text of the variable, instead
1299 of the backslashes before semicolons and special
1302 - Default Environment
1303 CONFIG_EXTRA_ENV_SETTINGS
1305 Define this to contain any number of null terminated
1306 strings (variable = value pairs) that will be part of
1307 the default enviroment compiled into the boot image.
1309 For example, place something like this in your
1310 board's config file:
1312 #define CONFIG_EXTRA_ENV_SETTINGS \
1316 Warning: This method is based on knowledge about the
1317 internal format how the environment is stored by the
1318 U-Boot code. This is NOT an official, exported
1319 interface! Although it is unlikely that this format
1320 will change soon, but there is no guarantee either.
1321 You better know what you are doing here.
1323 Note: overly (ab)use of the default environment is
1324 discouraged. Make sure to check other ways to preset
1325 the environment like the autoscript function or the
1329 CONFIG_HAS_DATAFLASH
1331 Defining this option enables DataFlash features and
1332 allows to read/write in Dataflash via the standard
1335 - Show boot progress
1336 CONFIG_SHOW_BOOT_PROGRESS
1338 Defining this option allows to add some board-
1339 specific code (calling a user-provided function
1340 "show_boot_progress(int)") that enables you to show
1341 the system's boot progress on some display (for
1342 example, some LED's) on your board. At the moment,
1343 the following checkpoints are implemented:
1346 1 common/cmd_bootm.c before attempting to boot an image
1347 -1 common/cmd_bootm.c Image header has bad magic number
1348 2 common/cmd_bootm.c Image header has correct magic number
1349 -2 common/cmd_bootm.c Image header has bad checksum
1350 3 common/cmd_bootm.c Image header has correct checksum
1351 -3 common/cmd_bootm.c Image data has bad checksum
1352 4 common/cmd_bootm.c Image data has correct checksum
1353 -4 common/cmd_bootm.c Image is for unsupported architecture
1354 5 common/cmd_bootm.c Architecture check OK
1355 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1356 6 common/cmd_bootm.c Image Type check OK
1357 -6 common/cmd_bootm.c gunzip uncompression error
1358 -7 common/cmd_bootm.c Unimplemented compression type
1359 7 common/cmd_bootm.c Uncompression OK
1360 -8 common/cmd_bootm.c Wrong Image Type (not kernel, multi, standalone)
1361 8 common/cmd_bootm.c Image Type check OK
1362 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1363 9 common/cmd_bootm.c Start initial ramdisk verification
1364 -10 common/cmd_bootm.c Ramdisk header has bad magic number
1365 -11 common/cmd_bootm.c Ramdisk header has bad checksum
1366 10 common/cmd_bootm.c Ramdisk header is OK
1367 -12 common/cmd_bootm.c Ramdisk data has bad checksum
1368 11 common/cmd_bootm.c Ramdisk data has correct checksum
1369 12 common/cmd_bootm.c Ramdisk verification complete, start loading
1370 -13 common/cmd_bootm.c Wrong Image Type (not PPC Linux Ramdisk)
1371 13 common/cmd_bootm.c Start multifile image verification
1372 14 common/cmd_bootm.c No initial ramdisk, no multifile, continue.
1373 15 common/cmd_bootm.c All preparation done, transferring control to OS
1375 -1 common/cmd_doc.c Bad usage of "doc" command
1376 -1 common/cmd_doc.c No boot device
1377 -1 common/cmd_doc.c Unknown Chip ID on boot device
1378 -1 common/cmd_doc.c Read Error on boot device
1379 -1 common/cmd_doc.c Image header has bad magic number
1381 -1 common/cmd_ide.c Bad usage of "ide" command
1382 -1 common/cmd_ide.c No boot device
1383 -1 common/cmd_ide.c Unknown boot device
1384 -1 common/cmd_ide.c Unknown partition table
1385 -1 common/cmd_ide.c Invalid partition type
1386 -1 common/cmd_ide.c Read Error on boot device
1387 -1 common/cmd_ide.c Image header has bad magic number
1389 -1 common/cmd_nvedit.c Environment not changable, but has bad CRC
1395 [so far only for SMDK2400 and TRAB boards]
1397 - Modem support endable:
1398 CONFIG_MODEM_SUPPORT
1400 - RTS/CTS Flow control enable:
1403 - Modem debug support:
1404 CONFIG_MODEM_SUPPORT_DEBUG
1406 Enables debugging stuff (char screen[1024], dbg())
1407 for modem support. Useful only with BDI2000.
1411 In the target system modem support is enabled when a
1412 specific key (key combination) is pressed during
1413 power-on. Otherwise U-Boot will boot normally
1414 (autoboot). The key_pressed() fuction is called from
1415 board_init(). Currently key_pressed() is a dummy
1416 function, returning 1 and thus enabling modem
1419 If there are no modem init strings in the
1420 environment, U-Boot proceed to autoboot; the
1421 previous output (banner, info printfs) will be
1424 See also: doc/README.Modem
1427 Configuration Settings:
1428 -----------------------
1430 - CFG_LONGHELP: Defined when you want long help messages included;
1431 undefine this when you're short of memory.
1433 - CFG_PROMPT: This is what U-Boot prints on the console to
1434 prompt for user input.
1436 - CFG_CBSIZE: Buffer size for input from the Console
1438 - CFG_PBSIZE: Buffer size for Console output
1440 - CFG_MAXARGS: max. Number of arguments accepted for monitor commands
1442 - CFG_BARGSIZE: Buffer size for Boot Arguments which are passed to
1443 the application (usually a Linux kernel) when it is
1446 - CFG_BAUDRATE_TABLE:
1447 List of legal baudrate settings for this board.
1449 - CFG_CONSOLE_INFO_QUIET
1450 Suppress display of console information at boot.
1452 - CFG_CONSOLE_IS_IN_ENV
1453 If the board specific function
1454 extern int overwrite_console (void);
1455 returns 1, the stdin, stderr and stdout are switched to the
1456 serial port, else the settings in the environment are used.
1458 - CFG_CONSOLE_OVERWRITE_ROUTINE
1459 Enable the call to overwrite_console().
1461 - CFG_CONSOLE_ENV_OVERWRITE
1462 Enable overwrite of previous console environment settings.
1464 - CFG_MEMTEST_START, CFG_MEMTEST_END:
1465 Begin and End addresses of the area used by the
1469 Enable an alternate, more extensive memory test.
1471 - CFG_TFTP_LOADADDR:
1472 Default load address for network file downloads
1474 - CFG_LOADS_BAUD_CHANGE:
1475 Enable temporary baudrate change while serial download
1478 Physical start address of SDRAM. _Must_ be 0 here.
1481 Physical start address of Motherboard I/O (if using a
1485 Physical start address of Flash memory.
1488 Physical start address of boot monitor code (set by
1489 make config files to be same as the text base address
1490 (TEXT_BASE) used when linking) - same as
1491 CFG_FLASH_BASE when booting from flash.
1494 Size of memory reserved for monitor code, used to
1495 determine _at_compile_time_ (!) if the environment is
1496 embedded within the U-Boot image, or in a separate
1500 Size of DRAM reserved for malloc() use.
1503 Maximum size of memory mapped by the startup code of
1504 the Linux kernel; all data that must be processed by
1505 the Linux kernel (bd_info, boot arguments, eventually
1506 initrd image) must be put below this limit.
1508 - CFG_MAX_FLASH_BANKS:
1509 Max number of Flash memory banks
1511 - CFG_MAX_FLASH_SECT:
1512 Max number of sectors on a Flash chip
1514 - CFG_FLASH_ERASE_TOUT:
1515 Timeout for Flash erase operations (in ms)
1517 - CFG_FLASH_WRITE_TOUT:
1518 Timeout for Flash write operations (in ms)
1520 - CFG_FLASH_LOCK_TOUT
1521 Timeout for Flash set sector lock bit operation (in ms)
1523 - CFG_FLASH_UNLOCK_TOUT
1524 Timeout for Flash clear lock bits operation (in ms)
1526 - CFG_FLASH_PROTECTION
1527 If defined, hardware flash sectors protection is used
1528 instead of U-Boot software protection.
1530 - CFG_DIRECT_FLASH_TFTP:
1532 Enable TFTP transfers directly to flash memory;
1533 without this option such a download has to be
1534 performed in two steps: (1) download to RAM, and (2)
1535 copy from RAM to flash.
1537 The two-step approach is usually more reliable, since
1538 you can check if the download worked before you erase
1539 the flash, but in some situations (when sytem RAM is
1540 too limited to allow for a tempory copy of the
1541 downloaded image) this option may be very useful.
1544 Define if the flash driver uses extra elements in the
1545 common flash structure for storing flash geometry
1547 - CFG_RX_ETH_BUFFER:
1548 Defines the number of ethernet receive buffers. On some
1549 ethernet controllers it is recommended to set this value
1550 to 8 or even higher (EEPRO100 or 405 EMAC), since all
1551 buffers can be full shortly after enabling the interface
1552 on high ethernet traffic.
1553 Defaults to 4 if not defined.
1555 The following definitions that deal with the placement and management
1556 of environment data (variable area); in general, we support the
1557 following configurations:
1559 - CFG_ENV_IS_IN_FLASH:
1561 Define this if the environment is in flash memory.
1563 a) The environment occupies one whole flash sector, which is
1564 "embedded" in the text segment with the U-Boot code. This
1565 happens usually with "bottom boot sector" or "top boot
1566 sector" type flash chips, which have several smaller
1567 sectors at the start or the end. For instance, such a
1568 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
1569 such a case you would place the environment in one of the
1570 4 kB sectors - with U-Boot code before and after it. With
1571 "top boot sector" type flash chips, you would put the
1572 environment in one of the last sectors, leaving a gap
1573 between U-Boot and the environment.
1577 Offset of environment data (variable area) to the
1578 beginning of flash memory; for instance, with bottom boot
1579 type flash chips the second sector can be used: the offset
1580 for this sector is given here.
1582 CFG_ENV_OFFSET is used relative to CFG_FLASH_BASE.
1586 This is just another way to specify the start address of
1587 the flash sector containing the environment (instead of
1590 - CFG_ENV_SECT_SIZE:
1592 Size of the sector containing the environment.
1595 b) Sometimes flash chips have few, equal sized, BIG sectors.
1596 In such a case you don't want to spend a whole sector for
1601 If you use this in combination with CFG_ENV_IS_IN_FLASH
1602 and CFG_ENV_SECT_SIZE, you can specify to use only a part
1603 of this flash sector for the environment. This saves
1604 memory for the RAM copy of the environment.
1606 It may also save flash memory if you decide to use this
1607 when your environment is "embedded" within U-Boot code,
1608 since then the remainder of the flash sector could be used
1609 for U-Boot code. It should be pointed out that this is
1610 STRONGLY DISCOURAGED from a robustness point of view:
1611 updating the environment in flash makes it always
1612 necessary to erase the WHOLE sector. If something goes
1613 wrong before the contents has been restored from a copy in
1614 RAM, your target system will be dead.
1616 - CFG_ENV_ADDR_REDUND
1619 These settings describe a second storage area used to hold
1620 a redundand copy of the environment data, so that there is
1621 a valid backup copy in case there is a power failure during
1622 a "saveenv" operation.
1624 BE CAREFUL! Any changes to the flash layout, and some changes to the
1625 source code will make it necessary to adapt <board>/u-boot.lds*
1629 - CFG_ENV_IS_IN_NVRAM:
1631 Define this if you have some non-volatile memory device
1632 (NVRAM, battery buffered SRAM) which you want to use for the
1638 These two #defines are used to determin the memory area you
1639 want to use for environment. It is assumed that this memory
1640 can just be read and written to, without any special
1643 BE CAREFUL! The first access to the environment happens quite early
1644 in U-Boot initalization (when we try to get the setting of for the
1645 console baudrate). You *MUST* have mappend your NVRAM area then, or
1648 Please note that even with NVRAM we still use a copy of the
1649 environment in RAM: we could work on NVRAM directly, but we want to
1650 keep settings there always unmodified except somebody uses "saveenv"
1651 to save the current settings.
1654 - CFG_ENV_IS_IN_EEPROM:
1656 Use this if you have an EEPROM or similar serial access
1657 device and a driver for it.
1662 These two #defines specify the offset and size of the
1663 environment area within the total memory of your EEPROM.
1665 - CFG_I2C_EEPROM_ADDR:
1666 If defined, specified the chip address of the EEPROM device.
1667 The default address is zero.
1669 - CFG_EEPROM_PAGE_WRITE_BITS:
1670 If defined, the number of bits used to address bytes in a
1671 single page in the EEPROM device. A 64 byte page, for example
1672 would require six bits.
1674 - CFG_EEPROM_PAGE_WRITE_DELAY_MS:
1675 If defined, the number of milliseconds to delay between
1676 page writes. The default is zero milliseconds.
1678 - CFG_I2C_EEPROM_ADDR_LEN:
1679 The length in bytes of the EEPROM memory array address. Note
1680 that this is NOT the chip address length!
1683 The size in bytes of the EEPROM device.
1686 - CFG_SPI_INIT_OFFSET
1688 Defines offset to the initial SPI buffer area in DPRAM. The
1689 area is used at an early stage (ROM part) if the environment
1690 is configured to reside in the SPI EEPROM: We need a 520 byte
1691 scratch DPRAM area. It is used between the two initialization
1692 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
1693 to be a good choice since it makes it far enough from the
1694 start of the data area as well as from the stack pointer.
1696 Please note that the environment is read-only as long as the monitor
1697 has been relocated to RAM and a RAM copy of the environment has been
1698 created; also, when using EEPROM you will have to use getenv_r()
1699 until then to read environment variables.
1701 The environment is protected by a CRC32 checksum. Before the monitor
1702 is relocated into RAM, as a result of a bad CRC you will be working
1703 with the compiled-in default environment - *silently*!!! [This is
1704 necessary, because the first environment variable we need is the
1705 "baudrate" setting for the console - if we have a bad CRC, we don't
1706 have any device yet where we could complain.]
1708 Note: once the monitor has been relocated, then it will complain if
1709 the default environment is used; a new CRC is computed as soon as you
1710 use the "saveenv" command to store a valid environment.
1713 Low Level (hardware related) configuration options:
1714 ---------------------------------------------------
1716 - CFG_CACHELINE_SIZE:
1717 Cache Line Size of the CPU.
1720 Default address of the IMMR after system reset.
1722 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
1723 and RPXsuper) to be able to adjust the position of
1724 the IMMR register after a reset.
1726 - Floppy Disk Support:
1727 CFG_FDC_DRIVE_NUMBER
1729 the default drive number (default value 0)
1733 defines the spacing between fdc chipset registers
1738 defines the offset of register from address. It
1739 depends on which part of the data bus is connected to
1740 the fdc chipset. (default value 0)
1742 If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
1743 CFG_FDC_DRIVE_NUMBER are undefined, they take their
1746 if CFG_FDC_HW_INIT is defined, then the function
1747 fdc_hw_init() is called at the beginning of the FDC
1748 setup. fdc_hw_init() must be provided by the board
1749 source code. It is used to make hardware dependant
1752 - CFG_IMMR: Physical address of the Internal Memory Mapped
1753 Register; DO NOT CHANGE! (11-4)
1754 [MPC8xx systems only]
1756 - CFG_INIT_RAM_ADDR:
1758 Start address of memory area tha can be used for
1759 initial data and stack; please note that this must be
1760 writable memory that is working WITHOUT special
1761 initialization, i. e. you CANNOT use normal RAM which
1762 will become available only after programming the
1763 memory controller and running certain initialization
1766 U-Boot uses the following memory types:
1767 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
1768 - MPC824X: data cache
1769 - PPC4xx: data cache
1771 - CFG_GBL_DATA_OFFSET:
1773 Offset of the initial data structure in the memory
1774 area defined by CFG_INIT_RAM_ADDR. Usually
1775 CFG_GBL_DATA_OFFSET is chosen such that the initial
1776 data is located at the end of the available space
1777 (sometimes written as (CFG_INIT_RAM_END -
1778 CFG_INIT_DATA_SIZE), and the initial stack is just
1779 below that area (growing from (CFG_INIT_RAM_ADDR +
1780 CFG_GBL_DATA_OFFSET) downward.
1783 On the MPC824X (or other systems that use the data
1784 cache for initial memory) the address chosen for
1785 CFG_INIT_RAM_ADDR is basically arbitrary - it must
1786 point to an otherwise UNUSED address space between
1787 the top of RAM and the start of the PCI space.
1789 - CFG_SIUMCR: SIU Module Configuration (11-6)
1791 - CFG_SYPCR: System Protection Control (11-9)
1793 - CFG_TBSCR: Time Base Status and Control (11-26)
1795 - CFG_PISCR: Periodic Interrupt Status and Control (11-31)
1797 - CFG_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
1799 - CFG_SCCR: System Clock and reset Control Register (15-27)
1801 - CFG_OR_TIMING_SDRAM:
1805 periodic timer for refresh
1807 - CFG_DER: Debug Event Register (37-47)
1809 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
1810 CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
1811 CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
1813 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
1815 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
1816 CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
1817 CFG_OR3_PRELIM, CFG_BR3_PRELIM:
1818 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
1820 - CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
1821 CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
1822 Machine Mode Register and Memory Periodic Timer
1823 Prescaler definitions (SDRAM timing)
1825 - CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
1826 enable I2C microcode relocation patch (MPC8xx);
1827 define relocation offset in DPRAM [DSP2]
1829 - CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
1830 enable SPI microcode relocation patch (MPC8xx);
1831 define relocation offset in DPRAM [SCC4]
1834 Use OSCM clock mode on MBX8xx board. Be careful,
1835 wrong setting might damage your board. Read
1836 doc/README.MBX before setting this variable!
1838 - CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
1839 Offset of the bootmode word in DPRAM used by post
1840 (Power On Self Tests). This definition overrides
1841 #define'd default value in commproc.h resp.
1844 - CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
1845 CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
1846 CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
1847 CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
1848 CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
1849 CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
1850 CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
1851 CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
1852 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
1854 Building the Software:
1855 ======================
1857 Building U-Boot has been tested in native PPC environments (on a
1858 PowerBook G3 running LinuxPPC 2000) and in cross environments
1859 (running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
1862 If you are not using a native PPC environment, it is assumed that you
1863 have the GNU cross compiling tools available in your path and named
1864 with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
1865 you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
1866 the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
1869 CROSS_COMPILE = ppc_4xx-
1872 U-Boot is intended to be simple to build. After installing the
1873 sources you must configure U-Boot for one specific board type. This
1878 where "NAME_config" is the name of one of the existing
1879 configurations; the following names are supported:
1881 ADCIOP_config GTH_config TQM850L_config
1882 ADS860_config IP860_config TQM855L_config
1883 AR405_config IVML24_config TQM860L_config
1884 CANBT_config IVMS8_config WALNUT405_config
1885 CPCI405_config LANTEC_config cogent_common_config
1886 CPCIISER4_config MBX_config cogent_mpc8260_config
1887 CU824_config MBX860T_config cogent_mpc8xx_config
1888 ESTEEM192E_config RPXlite_config hermes_config
1889 ETX094_config RPXsuper_config hymod_config
1890 FADS823_config SM850_config lwmon_config
1891 FADS850SAR_config SPD823TS_config pcu_e_config
1892 FADS860T_config SXNI855T_config rsdproto_config
1893 FPS850L_config Sandpoint8240_config sbc8260_config
1894 GENIETV_config TQM823L_config PIP405_config
1895 GEN860T_config EBONY_config FPS860L_config
1896 ELPT860_config cmi_mpc5xx_config NETVIA_config
1897 at91rm9200dk_config omap1510inn_config MPC8260ADS_config
1899 Note: for some board special configuration names may exist; check if
1900 additional information is available from the board vendor; for
1901 instance, the TQM8xxL systems run normally at 50 MHz and use a
1902 SCC for 10baseT ethernet; there are also systems with 80 MHz
1903 CPU clock, and an optional Fast Ethernet module is available
1904 for CPU's with FEC. You can select such additional "features"
1905 when chosing the configuration, i. e.
1908 - will configure for a plain TQM860L, i. e. 50MHz, no FEC
1910 make TQM860L_FEC_config
1911 - will configure for a TQM860L at 50MHz with FEC for ethernet
1913 make TQM860L_80MHz_config
1914 - will configure for a TQM860L at 80 MHz, with normal 10baseT
1917 make TQM860L_FEC_80MHz_config
1918 - will configure for a TQM860L at 80 MHz with FEC for ethernet
1920 make TQM823L_LCD_config
1921 - will configure for a TQM823L with U-Boot console on LCD
1923 make TQM823L_LCD_80MHz_config
1924 - will configure for a TQM823L at 80 MHz with U-Boot console on LCD
1929 Finally, type "make all", and you should get some working U-Boot
1930 images ready for downlod to / installation on your system:
1932 - "u-boot.bin" is a raw binary image
1933 - "u-boot" is an image in ELF binary format
1934 - "u-boot.srec" is in Motorola S-Record format
1937 Please be aware that the Makefiles assume you are using GNU make, so
1938 for instance on NetBSD you might need to use "gmake" instead of
1942 If the system board that you have is not listed, then you will need
1943 to port U-Boot to your hardware platform. To do this, follow these
1946 1. Add a new configuration option for your board to the toplevel
1947 "Makefile" and to the "MAKEALL" script, using the existing
1948 entries as examples. Note that here and at many other places
1949 boards and other names are listed alphabetically sorted. Please
1951 2. Create a new directory to hold your board specific code. Add any
1952 files you need. In your board directory, you will need at least
1953 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
1954 3. Create a new configuration file "include/configs/<board>.h" for
1956 3. If you're porting U-Boot to a new CPU, then also create a new
1957 directory to hold your CPU specific code. Add any files you need.
1958 4. Run "make <board>_config" with your new name.
1959 5. Type "make", and you should get a working "u-boot.srec" file
1960 to be installed on your target system.
1961 6. Debug and solve any problems that might arise.
1962 [Of course, this last step is much harder than it sounds.]
1965 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
1966 ==============================================================
1968 If you have modified U-Boot sources (for instance added a new board
1969 or support for new devices, a new CPU, etc.) you are expected to
1970 provide feedback to the other developers. The feedback normally takes
1971 the form of a "patch", i. e. a context diff against a certain (latest
1972 official or latest in CVS) version of U-Boot sources.
1974 But before you submit such a patch, please verify that your modifi-
1975 cation did not break existing code. At least make sure that *ALL* of
1976 the supported boards compile WITHOUT ANY compiler warnings. To do so,
1977 just run the "MAKEALL" script, which will configure and build U-Boot
1978 for ALL supported system. Be warned, this will take a while. You can
1979 select which (cross) compiler to use py passing a `CROSS_COMPILE'
1980 environment variable to the script, i. e. to use the cross tools from
1981 MontaVista's Hard Hat Linux you can type
1983 CROSS_COMPILE=ppc_8xx- MAKEALL
1985 or to build on a native PowerPC system you can type
1987 CROSS_COMPILE=' ' MAKEALL
1989 See also "U-Boot Porting Guide" below.
1992 Monitor Commands - Overview:
1993 ============================
1995 go - start application at address 'addr'
1996 run - run commands in an environment variable
1997 bootm - boot application image from memory
1998 bootp - boot image via network using BootP/TFTP protocol
1999 tftpboot- boot image via network using TFTP protocol
2000 and env variables "ipaddr" and "serverip"
2001 (and eventually "gatewayip")
2002 rarpboot- boot image via network using RARP/TFTP protocol
2003 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2004 loads - load S-Record file over serial line
2005 loadb - load binary file over serial line (kermit mode)
2007 mm - memory modify (auto-incrementing)
2008 nm - memory modify (constant address)
2009 mw - memory write (fill)
2011 cmp - memory compare
2012 crc32 - checksum calculation
2013 imd - i2c memory display
2014 imm - i2c memory modify (auto-incrementing)
2015 inm - i2c memory modify (constant address)
2016 imw - i2c memory write (fill)
2017 icrc32 - i2c checksum calculation
2018 iprobe - probe to discover valid I2C chip addresses
2019 iloop - infinite loop on address range
2020 isdram - print SDRAM configuration information
2021 sspi - SPI utility commands
2022 base - print or set address offset
2023 printenv- print environment variables
2024 setenv - set environment variables
2025 saveenv - save environment variables to persistent storage
2026 protect - enable or disable FLASH write protection
2027 erase - erase FLASH memory
2028 flinfo - print FLASH memory information
2029 bdinfo - print Board Info structure
2030 iminfo - print header information for application image
2031 coninfo - print console devices and informations
2032 ide - IDE sub-system
2033 loop - infinite loop on address range
2034 mtest - simple RAM test
2035 icache - enable or disable instruction cache
2036 dcache - enable or disable data cache
2037 reset - Perform RESET of the CPU
2038 echo - echo args to console
2039 version - print monitor version
2040 help - print online help
2041 ? - alias for 'help'
2044 Monitor Commands - Detailed Description:
2045 ========================================
2049 For now: just type "help <command>".
2052 Environment Variables:
2053 ======================
2055 U-Boot supports user configuration using Environment Variables which
2056 can be made persistent by saving to Flash memory.
2058 Environment Variables are set using "setenv", printed using
2059 "printenv", and saved to Flash using "saveenv". Using "setenv"
2060 without a value can be used to delete a variable from the
2061 environment. As long as you don't save the environment you are
2062 working with an in-memory copy. In case the Flash area containing the
2063 environment is erased by accident, a default environment is provided.
2065 Some configuration options can be set using Environment Variables:
2067 baudrate - see CONFIG_BAUDRATE
2069 bootdelay - see CONFIG_BOOTDELAY
2071 bootcmd - see CONFIG_BOOTCOMMAND
2073 bootargs - Boot arguments when booting an RTOS image
2075 bootfile - Name of the image to load with TFTP
2077 autoload - if set to "no" (any string beginning with 'n'),
2078 "bootp" will just load perform a lookup of the
2079 configuration from the BOOTP server, but not try to
2080 load any image using TFTP
2082 autostart - if set to "yes", an image loaded using the "bootp",
2083 "rarpboot", "tftpboot" or "diskboot" commands will
2084 be automatically started (by internally calling
2087 If set to "no", a standalone image passed to the
2088 "bootm" command will be copied to the load address
2089 (and eventually uncompressed), but NOT be started.
2090 This can be used to load and uncompress arbitrary
2093 initrd_high - restrict positioning of initrd images:
2094 If this variable is not set, initrd images will be
2095 copied to the highest possible address in RAM; this
2096 is usually what you want since it allows for
2097 maximum initrd size. If for some reason you want to
2098 make sure that the initrd image is loaded below the
2099 CFG_BOOTMAPSZ limit, you can set this environment
2100 variable to a value of "no" or "off" or "0".
2101 Alternatively, you can set it to a maximum upper
2102 address to use (U-Boot will still check that it
2103 does not overwrite the U-Boot stack and data).
2105 For instance, when you have a system with 16 MB
2106 RAM, and want to reseve 4 MB from use by Linux,
2107 you can do this by adding "mem=12M" to the value of
2108 the "bootargs" variable. However, now you must make
2109 sure, that the initrd image is placed in the first
2110 12 MB as well - this can be done with
2112 setenv initrd_high 00c00000
2114 If you set initrd_high to 0xFFFFFFFF, this is an
2115 indication to U-Boot that all addresses are legal
2116 for the Linux kernel, including addresses in flash
2117 memory. In this case U-Boot will NOT COPY the
2118 ramdisk at all. This may be useful to reduce the
2119 boot time on your system, but requires that this
2120 feature is supported by your Linux kernel.
2122 ipaddr - IP address; needed for tftpboot command
2124 loadaddr - Default load address for commands like "bootp",
2125 "rarpboot", "tftpboot", "loadb" or "diskboot"
2127 loads_echo - see CONFIG_LOADS_ECHO
2129 serverip - TFTP server IP address; needed for tftpboot command
2131 bootretry - see CONFIG_BOOT_RETRY_TIME
2133 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2135 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2138 The following environment variables may be used and automatically
2139 updated by the network boot commands ("bootp" and "rarpboot"),
2140 depending the information provided by your boot server:
2142 bootfile - see above
2143 dnsip - IP address of your Domain Name Server
2144 dnsip2 - IP address of your secondary Domain Name Server
2145 gatewayip - IP address of the Gateway (Router) to use
2146 hostname - Target hostname
2148 netmask - Subnet Mask
2149 rootpath - Pathname of the root filesystem on the NFS server
2150 serverip - see above
2153 There are two special Environment Variables:
2155 serial# - contains hardware identification information such
2156 as type string and/or serial number
2157 ethaddr - Ethernet address
2159 These variables can be set only once (usually during manufacturing of
2160 the board). U-Boot refuses to delete or overwrite these variables
2161 once they have been set once.
2164 Further special Environment Variables:
2166 ver - Contains the U-Boot version string as printed
2167 with the "version" command. This variable is
2168 readonly (see CONFIG_VERSION_VARIABLE).
2171 Please note that changes to some configuration parameters may take
2172 only effect after the next boot (yes, that's just like Windoze :-).
2175 Command Line Parsing:
2176 =====================
2178 There are two different command line parsers available with U-Boot:
2179 the old "simple" one, and the much more pwerful "hush" shell:
2181 Old, simple command line parser:
2182 --------------------------------
2184 - supports environment variables (through setenv / saveenv commands)
2185 - several commands on one line, separated by ';'
2186 - variable substitution using "... $(name) ..." syntax
2187 - special characters ('$', ';') can be escaped by prefixing with '\',
2189 setenv bootcmd bootm \$(address)
2190 - You can also escape text by enclosing in single apostrophes, for example:
2191 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
2196 - similar to Bourne shell, with control structures like
2197 if...then...else...fi, for...do...done; while...do...done,
2198 until...do...done, ...
2199 - supports environment ("global") variables (through setenv / saveenv
2200 commands) and local shell variables (through standard shell syntax
2201 "name=value"); only environment variables can be used with "run"
2207 (1) If a command line (or an environment variable executed by a "run"
2208 command) contains several commands separated by semicolon, and
2209 one of these commands fails, then the remaining commands will be
2212 (2) If you execute several variables with one call to run (i. e.
2213 calling run with a list af variables as arguments), any failing
2214 command will cause "run" to terminate, i. e. the remaining
2215 variables are not executed.
2217 Note for Redundant Ethernet Interfaces:
2218 =======================================
2220 Some boards come with redundand ethernet interfaces; U-Boot supports
2221 such configurations and is capable of automatic selection of a
2222 "working" interface when needed. MAC assignemnt works as follows:
2224 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2225 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2226 "eth1addr" (=>eth1), "eth2addr", ...
2228 If the network interface stores some valid MAC address (for instance
2229 in SROM), this is used as default address if there is NO correspon-
2230 ding setting in the environment; if the corresponding environment
2231 variable is set, this overrides the settings in the card; that means:
2233 o If the SROM has a valid MAC address, and there is no address in the
2234 environment, the SROM's address is used.
2236 o If there is no valid address in the SROM, and a definition in the
2237 environment exists, then the value from the environment variable is
2240 o If both the SROM and the environment contain a MAC address, and
2241 both addresses are the same, this MAC address is used.
2243 o If both the SROM and the environment contain a MAC address, and the
2244 addresses differ, the value from the environment is used and a
2247 o If neither SROM nor the environment contain a MAC address, an error
2254 The "boot" commands of this monitor operate on "image" files which
2255 can be basicly anything, preceeded by a special header; see the
2256 definitions in include/image.h for details; basicly, the header
2257 defines the following image properties:
2259 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2260 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2261 LynxOS, pSOS, QNX, RTEMS, ARTOS;
2262 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
2263 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2264 IA64, MIPS, MIPS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2265 Currently supported: PowerPC).
2266 * Compression Type (Provisions for uncompressed, gzip, bzip2;
2267 Currently supported: uncompressed, gzip).
2273 The header is marked by a special Magic Number, and both the header
2274 and the data portions of the image are secured against corruption by
2281 Although U-Boot should support any OS or standalone application
2282 easily, Linux has always been in the focus during the design of
2285 U-Boot includes many features that so far have been part of some
2286 special "boot loader" code within the Linux kernel. Also, any
2287 "initrd" images to be used are no longer part of one big Linux image;
2288 instead, kernel and "initrd" are separate images. This implementation
2289 serves serveral purposes:
2291 - the same features can be used for other OS or standalone
2292 applications (for instance: using compressed images to reduce the
2293 Flash memory footprint)
2295 - it becomes much easier to port new Linux kernel versions because
2296 lots of low-level, hardware dependend stuff are done by U-Boot
2298 - the same Linux kernel image can now be used with different "initrd"
2299 images; of course this also means that different kernel images can
2300 be run with the same "initrd". This makes testing easier (you don't
2301 have to build a new "zImage.initrd" Linux image when you just
2302 change a file in your "initrd"). Also, a field-upgrade of the
2303 software is easier now.
2309 Porting Linux to U-Boot based systems:
2310 ---------------------------------------
2312 U-Boot cannot save you from doing all the necessary modifications to
2313 configure the Linux device drivers for use with your target hardware
2314 (no, we don't intend to provide a full virtual machine interface to
2317 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
2319 Just make sure your machine specific header file (for instance
2320 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2321 Information structure as we define in include/u-boot.h, and make
2322 sure that your definition of IMAP_ADDR uses the same value as your
2323 U-Boot configuration in CFG_IMMR.
2326 Configuring the Linux kernel:
2327 -----------------------------
2329 No specific requirements for U-Boot. Make sure you have some root
2330 device (initial ramdisk, NFS) for your target system.
2333 Building a Linux Image:
2334 -----------------------
2336 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2337 not used. If you use recent kernel source, a new build target
2338 "uImage" will exist which automatically builds an image usable by
2339 U-Boot. Most older kernels also have support for a "pImage" target,
2340 which was introduced for our predecessor project PPCBoot and uses a
2341 100% compatible format.
2350 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2351 encapsulate a compressed Linux kernel image with header information,
2352 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2354 * build a standard "vmlinux" kernel image (in ELF binary format):
2356 * convert the kernel into a raw binary image:
2358 ${CROSS_COMPILE}-objcopy -O binary \
2359 -R .note -R .comment \
2360 -S vmlinux linux.bin
2362 * compress the binary image:
2366 * package compressed binary image for U-Boot:
2368 mkimage -A ppc -O linux -T kernel -C gzip \
2369 -a 0 -e 0 -n "Linux Kernel Image" \
2370 -d linux.bin.gz uImage
2373 The "mkimage" tool can also be used to create ramdisk images for use
2374 with U-Boot, either separated from the Linux kernel image, or
2375 combined into one file. "mkimage" encapsulates the images with a 64
2376 byte header containing information about target architecture,
2377 operating system, image type, compression method, entry points, time
2378 stamp, CRC32 checksums, etc.
2380 "mkimage" can be called in two ways: to verify existing images and
2381 print the header information, or to build new images.
2383 In the first form (with "-l" option) mkimage lists the information
2384 contained in the header of an existing U-Boot image; this includes
2385 checksum verification:
2387 tools/mkimage -l image
2388 -l ==> list image header information
2390 The second form (with "-d" option) is used to build a U-Boot image
2391 from a "data file" which is used as image payload:
2393 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2394 -n name -d data_file image
2395 -A ==> set architecture to 'arch'
2396 -O ==> set operating system to 'os'
2397 -T ==> set image type to 'type'
2398 -C ==> set compression type 'comp'
2399 -a ==> set load address to 'addr' (hex)
2400 -e ==> set entry point to 'ep' (hex)
2401 -n ==> set image name to 'name'
2402 -d ==> use image data from 'datafile'
2404 Right now, all Linux kernels use the same load address (0x00000000),
2405 but the entry point address depends on the kernel version:
2407 - 2.2.x kernels have the entry point at 0x0000000C,
2408 - 2.3.x and later kernels have the entry point at 0x00000000.
2410 So a typical call to build a U-Boot image would read:
2412 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2413 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2414 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
2415 > examples/uImage.TQM850L
2416 Image Name: 2.4.4 kernel for TQM850L
2417 Created: Wed Jul 19 02:34:59 2000
2418 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2419 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2420 Load Address: 0x00000000
2421 Entry Point: 0x00000000
2423 To verify the contents of the image (or check for corruption):
2425 -> tools/mkimage -l examples/uImage.TQM850L
2426 Image Name: 2.4.4 kernel for TQM850L
2427 Created: Wed Jul 19 02:34:59 2000
2428 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2429 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2430 Load Address: 0x00000000
2431 Entry Point: 0x00000000
2433 NOTE: for embedded systems where boot time is critical you can trade
2434 speed for memory and install an UNCOMPRESSED image instead: this
2435 needs more space in Flash, but boots much faster since it does not
2436 need to be uncompressed:
2438 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
2439 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2440 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2441 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
2442 > examples/uImage.TQM850L-uncompressed
2443 Image Name: 2.4.4 kernel for TQM850L
2444 Created: Wed Jul 19 02:34:59 2000
2445 Image Type: PowerPC Linux Kernel Image (uncompressed)
2446 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2447 Load Address: 0x00000000
2448 Entry Point: 0x00000000
2451 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2452 when your kernel is intended to use an initial ramdisk:
2454 -> tools/mkimage -n 'Simple Ramdisk Image' \
2455 > -A ppc -O linux -T ramdisk -C gzip \
2456 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2457 Image Name: Simple Ramdisk Image
2458 Created: Wed Jan 12 14:01:50 2000
2459 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2460 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2461 Load Address: 0x00000000
2462 Entry Point: 0x00000000
2465 Installing a Linux Image:
2466 -------------------------
2468 To downloading a U-Boot image over the serial (console) interface,
2469 you must convert the image to S-Record format:
2471 objcopy -I binary -O srec examples/image examples/image.srec
2473 The 'objcopy' does not understand the information in the U-Boot
2474 image header, so the resulting S-Record file will be relative to
2475 address 0x00000000. To load it to a given address, you need to
2476 specify the target address as 'offset' parameter with the 'loads'
2479 Example: install the image to address 0x40100000 (which on the
2480 TQM8xxL is in the first Flash bank):
2482 => erase 40100000 401FFFFF
2488 ## Ready for S-Record download ...
2489 ~>examples/image.srec
2490 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2492 15989 15990 15991 15992
2493 [file transfer complete]
2495 ## Start Addr = 0x00000000
2498 You can check the success of the download using the 'iminfo' command;
2499 this includes a checksum verification so you can be sure no data
2500 corruption happened:
2504 ## Checking Image at 40100000 ...
2505 Image Name: 2.2.13 for initrd on TQM850L
2506 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2507 Data Size: 335725 Bytes = 327 kB = 0 MB
2508 Load Address: 00000000
2509 Entry Point: 0000000c
2510 Verifying Checksum ... OK
2516 The "bootm" command is used to boot an application that is stored in
2517 memory (RAM or Flash). In case of a Linux kernel image, the contents
2518 of the "bootargs" environment variable is passed to the kernel as
2519 parameters. You can check and modify this variable using the
2520 "printenv" and "setenv" commands:
2523 => printenv bootargs
2524 bootargs=root=/dev/ram
2526 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2528 => printenv bootargs
2529 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2532 ## Booting Linux kernel at 40020000 ...
2533 Image Name: 2.2.13 for NFS on TQM850L
2534 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2535 Data Size: 381681 Bytes = 372 kB = 0 MB
2536 Load Address: 00000000
2537 Entry Point: 0000000c
2538 Verifying Checksum ... OK
2539 Uncompressing Kernel Image ... OK
2540 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
2541 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2542 time_init: decrementer frequency = 187500000/60
2543 Calibrating delay loop... 49.77 BogoMIPS
2544 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2547 If you want to boot a Linux kernel with initial ram disk, you pass
2548 the memory addreses of both the kernel and the initrd image (PPBCOOT
2549 format!) to the "bootm" command:
2551 => imi 40100000 40200000
2553 ## Checking Image at 40100000 ...
2554 Image Name: 2.2.13 for initrd on TQM850L
2555 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2556 Data Size: 335725 Bytes = 327 kB = 0 MB
2557 Load Address: 00000000
2558 Entry Point: 0000000c
2559 Verifying Checksum ... OK
2561 ## Checking Image at 40200000 ...
2562 Image Name: Simple Ramdisk Image
2563 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2564 Data Size: 566530 Bytes = 553 kB = 0 MB
2565 Load Address: 00000000
2566 Entry Point: 00000000
2567 Verifying Checksum ... OK
2569 => bootm 40100000 40200000
2570 ## Booting Linux kernel at 40100000 ...
2571 Image Name: 2.2.13 for initrd on TQM850L
2572 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2573 Data Size: 335725 Bytes = 327 kB = 0 MB
2574 Load Address: 00000000
2575 Entry Point: 0000000c
2576 Verifying Checksum ... OK
2577 Uncompressing Kernel Image ... OK
2578 ## Loading RAMDisk Image at 40200000 ...
2579 Image Name: Simple Ramdisk Image
2580 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2581 Data Size: 566530 Bytes = 553 kB = 0 MB
2582 Load Address: 00000000
2583 Entry Point: 00000000
2584 Verifying Checksum ... OK
2585 Loading Ramdisk ... OK
2586 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
2587 Boot arguments: root=/dev/ram
2588 time_init: decrementer frequency = 187500000/60
2589 Calibrating delay loop... 49.77 BogoMIPS
2591 RAMDISK: Compressed image found at block 0
2592 VFS: Mounted root (ext2 filesystem).
2596 More About U-Boot Image Types:
2597 ------------------------------
2599 U-Boot supports the following image types:
2601 "Standalone Programs" are directly runnable in the environment
2602 provided by U-Boot; it is expected that (if they behave
2603 well) you can continue to work in U-Boot after return from
2604 the Standalone Program.
2605 "OS Kernel Images" are usually images of some Embedded OS which
2606 will take over control completely. Usually these programs
2607 will install their own set of exception handlers, device
2608 drivers, set up the MMU, etc. - this means, that you cannot
2609 expect to re-enter U-Boot except by resetting the CPU.
2610 "RAMDisk Images" are more or less just data blocks, and their
2611 parameters (address, size) are passed to an OS kernel that is
2613 "Multi-File Images" contain several images, typically an OS
2614 (Linux) kernel image and one or more data images like
2615 RAMDisks. This construct is useful for instance when you want
2616 to boot over the network using BOOTP etc., where the boot
2617 server provides just a single image file, but you want to get
2618 for instance an OS kernel and a RAMDisk image.
2620 "Multi-File Images" start with a list of image sizes, each
2621 image size (in bytes) specified by an "uint32_t" in network
2622 byte order. This list is terminated by an "(uint32_t)0".
2623 Immediately after the terminating 0 follow the images, one by
2624 one, all aligned on "uint32_t" boundaries (size rounded up to
2625 a multiple of 4 bytes).
2627 "Firmware Images" are binary images containing firmware (like
2628 U-Boot or FPGA images) which usually will be programmed to
2631 "Script files" are command sequences that will be executed by
2632 U-Boot's command interpreter; this feature is especially
2633 useful when you configure U-Boot to use a real shell (hush)
2634 as command interpreter.
2640 One of the features of U-Boot is that you can dynamically load and
2641 run "standalone" applications, which can use some resources of
2642 U-Boot like console I/O functions or interrupt services.
2644 Two simple examples are included with the sources:
2649 'examples/hello_world.c' contains a small "Hello World" Demo
2650 application; it is automatically compiled when you build U-Boot.
2651 It's configured to run at address 0x00040004, so you can play with it
2655 ## Ready for S-Record download ...
2656 ~>examples/hello_world.srec
2657 1 2 3 4 5 6 7 8 9 10 11 ...
2658 [file transfer complete]
2660 ## Start Addr = 0x00040004
2662 => go 40004 Hello World! This is a test.
2663 ## Starting application at 0x00040004 ...
2674 Hit any key to exit ...
2676 ## Application terminated, rc = 0x0
2678 Another example, which demonstrates how to register a CPM interrupt
2679 handler with the U-Boot code, can be found in 'examples/timer.c'.
2680 Here, a CPM timer is set up to generate an interrupt every second.
2681 The interrupt service routine is trivial, just printing a '.'
2682 character, but this is just a demo program. The application can be
2683 controlled by the following keys:
2685 ? - print current values og the CPM Timer registers
2686 b - enable interrupts and start timer
2687 e - stop timer and disable interrupts
2688 q - quit application
2691 ## Ready for S-Record download ...
2692 ~>examples/timer.srec
2693 1 2 3 4 5 6 7 8 9 10 11 ...
2694 [file transfer complete]
2696 ## Start Addr = 0x00040004
2699 ## Starting application at 0x00040004 ...
2702 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2705 [q, b, e, ?] Set interval 1000000 us
2708 [q, b, e, ?] ........
2709 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2712 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2715 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2718 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2720 [q, b, e, ?] ...Stopping timer
2722 [q, b, e, ?] ## Application terminated, rc = 0x0
2728 Over time, many people have reported problems when trying to used the
2729 "minicom" terminal emulation program for serial download. I (wd)
2730 consider minicom to be broken, and recommend not to use it. Under
2731 Unix, I recommend to use C-Kermit for general purpose use (and
2732 especially for kermit binary protocol download ("loadb" command), and
2733 use "cu" for S-Record download ("loads" command).
2735 Nevertheless, if you absolutely want to use it try adding this
2736 configuration to your "File transfer protocols" section:
2738 Name Program Name U/D FullScr IO-Red. Multi
2739 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2740 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2746 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2747 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2749 Building requires a cross environment; it is known to work on
2750 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2751 need gmake since the Makefiles are not compatible with BSD make).
2752 Note that the cross-powerpc package does not install include files;
2753 attempting to build U-Boot will fail because <machine/ansi.h> is
2754 missing. This file has to be installed and patched manually:
2756 # cd /usr/pkg/cross/powerpc-netbsd/include
2758 # ln -s powerpc machine
2759 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2760 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2762 Native builds *don't* work due to incompatibilities between native
2763 and U-Boot include files.
2765 Booting assumes that (the first part of) the image booted is a
2766 stage-2 loader which in turn loads and then invokes the kernel
2767 proper. Loader sources will eventually appear in the NetBSD source
2768 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2769 meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
2773 Implementation Internals:
2774 =========================
2776 The following is not intended to be a complete description of every
2777 implementation detail. However, it should help to understand the
2778 inner workings of U-Boot and make it easier to port it to custom
2782 Initial Stack, Global Data:
2783 ---------------------------
2785 The implementation of U-Boot is complicated by the fact that U-Boot
2786 starts running out of ROM (flash memory), usually without access to
2787 system RAM (because the memory controller is not initialized yet).
2788 This means that we don't have writable Data or BSS segments, and BSS
2789 is not initialized as zero. To be able to get a C environment working
2790 at all, we have to allocate at least a minimal stack. Implementation
2791 options for this are defined and restricted by the CPU used: Some CPU
2792 models provide on-chip memory (like the IMMR area on MPC8xx and
2793 MPC826x processors), on others (parts of) the data cache can be
2794 locked as (mis-) used as memory, etc.
2796 Chris Hallinan posted a good summy of these issues to the
2797 u-boot-users mailing list:
2799 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2800 From: "Chris Hallinan" <clh@net1plus.com>
2801 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2804 Correct me if I'm wrong, folks, but the way I understand it
2805 is this: Using DCACHE as initial RAM for Stack, etc, does not
2806 require any physical RAM backing up the cache. The cleverness
2807 is that the cache is being used as a temporary supply of
2808 necessary storage before the SDRAM controller is setup. It's
2809 beyond the scope of this list to expain the details, but you
2810 can see how this works by studying the cache architecture and
2811 operation in the architecture and processor-specific manuals.
2813 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2814 is another option for the system designer to use as an
2815 initial stack/ram area prior to SDRAM being available. Either
2816 option should work for you. Using CS 4 should be fine if your
2817 board designers haven't used it for something that would
2818 cause you grief during the initial boot! It is frequently not
2821 CFG_INIT_RAM_ADDR should be somewhere that won't interfere
2822 with your processor/board/system design. The default value
2823 you will find in any recent u-boot distribution in
2824 Walnut405.h should work for you. I'd set it to a value larger
2825 than your SDRAM module. If you have a 64MB SDRAM module, set
2826 it above 400_0000. Just make sure your board has no resources
2827 that are supposed to respond to that address! That code in
2828 start.S has been around a while and should work as is when
2829 you get the config right.
2834 It is essential to remember this, since it has some impact on the C
2835 code for the initialization procedures:
2837 * Initialized global data (data segment) is read-only. Do not attempt
2840 * Do not use any unitialized global data (or implicitely initialized
2841 as zero data - BSS segment) at all - this is undefined, initiali-
2842 zation is performed later (when relocationg to RAM).
2844 * Stack space is very limited. Avoid big data buffers or things like
2847 Having only the stack as writable memory limits means we cannot use
2848 normal global data to share information beween the code. But it
2849 turned out that the implementation of U-Boot can be greatly
2850 simplified by making a global data structure (gd_t) available to all
2851 functions. We could pass a pointer to this data as argument to _all_
2852 functions, but this would bloat the code. Instead we use a feature of
2853 the GCC compiler (Global Register Variables) to share the data: we
2854 place a pointer (gd) to the global data into a register which we
2855 reserve for this purpose.
2857 When chosing a register for such a purpose we are restricted by the
2858 relevant (E)ABI specifications for the current architecture, and by
2859 GCC's implementation.
2861 For PowerPC, the following registers have specific use:
2864 R3-R4: parameter passing and return values
2865 R5-R10: parameter passing
2866 R13: small data area pointer
2870 (U-Boot also uses R14 as internal GOT pointer.)
2872 ==> U-Boot will use R29 to hold a pointer to the global data
2874 Note: on PPC, we could use a static initializer (since the
2875 address of the global data structure is known at compile time),
2876 but it turned out that reserving a register results in somewhat
2877 smaller code - although the code savings are not that big (on
2878 average for all boards 752 bytes for the whole U-Boot image,
2879 624 text + 127 data).
2881 On ARM, the following registers are used:
2883 R0: function argument word/integer result
2884 R1-R3: function argument word
2886 R10: stack limit (used only if stack checking if enabled)
2887 R11: argument (frame) pointer
2888 R12: temporary workspace
2891 R15: program counter
2893 ==> U-Boot will use R8 to hold a pointer to the global data
2899 U-Boot runs in system state and uses physical addresses, i.e. the
2900 MMU is not used either for address mapping nor for memory protection.
2902 The available memory is mapped to fixed addresses using the memory
2903 controller. In this process, a contiguous block is formed for each
2904 memory type (Flash, SDRAM, SRAM), even when it consists of several
2905 physical memory banks.
2907 U-Boot is installed in the first 128 kB of the first Flash bank (on
2908 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
2909 booting and sizing and initializing DRAM, the code relocates itself
2910 to the upper end of DRAM. Immediately below the U-Boot code some
2911 memory is reserved for use by malloc() [see CFG_MALLOC_LEN
2912 configuration setting]. Below that, a structure with global Board
2913 Info data is placed, followed by the stack (growing downward).
2915 Additionally, some exception handler code is copied to the low 8 kB
2916 of DRAM (0x00000000 ... 0x00001FFF).
2918 So a typical memory configuration with 16 MB of DRAM could look like
2921 0x0000 0000 Exception Vector code
2924 0x0000 2000 Free for Application Use
2930 0x00FB FF20 Monitor Stack (Growing downward)
2931 0x00FB FFAC Board Info Data and permanent copy of global data
2932 0x00FC 0000 Malloc Arena
2935 0x00FE 0000 RAM Copy of Monitor Code
2936 ... eventually: LCD or video framebuffer
2937 ... eventually: pRAM (Protected RAM - unchanged by reset)
2938 0x00FF FFFF [End of RAM]
2941 System Initialization:
2942 ----------------------
2944 In the reset configuration, U-Boot starts at the reset entry point
2945 (on most PowerPC systens at address 0x00000100). Because of the reset
2946 configuration for CS0# this is a mirror of the onboard Flash memory.
2947 To be able to re-map memory U-Boot then jumps to it's link address.
2948 To be able to implement the initialization code in C, a (small!)
2949 initial stack is set up in the internal Dual Ported RAM (in case CPUs
2950 which provide such a feature like MPC8xx or MPC8260), or in a locked
2951 part of the data cache. After that, U-Boot initializes the CPU core,
2952 the caches and the SIU.
2954 Next, all (potentially) available memory banks are mapped using a
2955 preliminary mapping. For example, we put them on 512 MB boundaries
2956 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
2957 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
2958 programmed for SDRAM access. Using the temporary configuration, a
2959 simple memory test is run that determines the size of the SDRAM
2962 When there is more than one SDRAM bank, and the banks are of
2963 different size, the larger is mapped first. For equal size, the first
2964 bank (CS2#) is mapped first. The first mapping is always for address
2965 0x00000000, with any additional banks following immediately to create
2966 contiguous memory starting from 0.
2968 Then, the monitor installs itself at the upper end of the SDRAM area
2969 and allocates memory for use by malloc() and for the global Board
2970 Info data; also, the exception vector code is copied to the low RAM
2971 pages, and the final stack is set up.
2973 Only after this relocation will you have a "normal" C environment;
2974 until that you are restricted in several ways, mostly because you are
2975 running from ROM, and because the code will have to be relocated to a
2979 U-Boot Porting Guide:
2980 ----------------------
2982 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
2986 int main (int argc, char *argv[])
2988 sighandler_t no_more_time;
2990 signal (SIGALRM, no_more_time);
2991 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
2993 if (available_money > available_manpower) {
2994 pay consultant to port U-Boot;
2998 Download latest U-Boot source;
3000 Subscribe to u-boot-users mailing list;
3003 email ("Hi, I am new to U-Boot, how do I get started?");
3007 Read the README file in the top level directory;
3008 Read http://www.denx.de/re/DPLG.html
3009 Read the source, Luke;
3012 if (available_money > toLocalCurrency ($2500)) {
3015 Add a lot of aggravation and time;
3018 Create your own board support subdirectory;
3020 Create your own board config file;
3024 Add / modify source code;
3028 email ("Hi, I am having problems...");
3030 Send patch file to Wolfgang;
3035 void no_more_time (int sig)
3044 All contributions to U-Boot should conform to the Linux kernel
3045 coding style; see the file "Documentation/CodingStyle" in your Linux
3046 kernel source directory.
3048 Please note that U-Boot is implemented in C (and to some small parts
3049 in Assembler); no C++ is used, so please do not use C++ style
3050 comments (//) in your code.
3052 Submissions which do not conform to the standards may be returned
3053 with a request to reformat the changes.
3059 Since the number of patches for U-Boot is growing, we need to
3060 establish some rules. Submissions which do not conform to these rules
3061 may be rejected, even when they contain important and valuable stuff.
3064 When you send a patch, please include the following information with
3067 * For bug fixes: a description of the bug and how your patch fixes
3068 this bug. Please try to include a way of demonstrating that the
3069 patch actually fixes something.
3071 * For new features: a description of the feature and your
3074 * A CHANGELOG entry as plaintext (separate from the patch)
3076 * For major contributions, your entry to the CREDITS file
3078 * When you add support for a new board, don't forget to add this
3079 board to the MAKEALL script, too.
3081 * If your patch adds new configuration options, don't forget to
3082 document these in the README file.
3084 * The patch itself. If you are accessing the CVS repository use "cvs
3085 update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
3086 version of diff does not support these options, then get the latest
3087 version of GNU diff.
3089 The current directory when running this command shall be the top
3090 level directory of the U-Boot source tree, or it's parent directory
3091 (i. e. please make sure that your patch includes sufficient
3092 directory information for the affected files).
3094 We accept patches as plain text, MIME attachments or as uuencoded
3097 * If one logical set of modifications affects or creates several
3098 files, all these changes shall be submitted in a SINGLE patch file.
3100 * Changesets that contain different, unrelated modifications shall be
3101 submitted as SEPARATE patches, one patch per changeset.
3106 * Before sending the patch, run the MAKEALL script on your patched
3107 source tree and make sure that no errors or warnings are reported
3108 for any of the boards.
3110 * Keep your modifications to the necessary minimum: A patch
3111 containing several unrelated changes or arbitrary reformats will be
3112 returned with a request to re-formatting / split it.
3114 * If you modify existing code, make sure that your new code does not
3115 add to the memory footprint of the code ;-) Small is beautiful!
3116 When adding new features, these should compile conditionally only
3117 (using #ifdef), and the resulting code with the new feature
3118 disabled must not need more memory than the old code without your
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