2 # (C) Copyright 2000 - 2008
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, ARM, MIPS and several other
29 processors, which can be installed in a boot ROM and used to
30 initialize and test the hardware or to download and run application
33 The development of U-Boot is closely related to Linux: some parts of
34 the source code originate in the Linux source tree, we have some
35 header files in common, and special provision has been made to
36 support booting of Linux images.
38 Some attention has been paid to make this software easily
39 configurable and extendable. For instance, all monitor commands are
40 implemented with the same call interface, so that it's very easy to
41 add new commands. Also, instead of permanently adding rarely used
42 code (for instance hardware test utilities) to the monitor, you can
43 load and run it dynamically.
49 In general, all boards for which a configuration option exists in the
50 Makefile have been tested to some extent and can be considered
51 "working". In fact, many of them are used in production systems.
53 In case of problems see the CHANGELOG and CREDITS files to find out
54 who contributed the specific port. The MAINTAINERS file lists board
61 In case you have questions about, problems with or contributions for
62 U-Boot you should send a message to the U-Boot mailing list at
63 <u-boot@lists.denx.de>. There is also an archive of previous traffic
64 on the mailing list - please search the archive before asking FAQ's.
65 Please see http://lists.denx.de/pipermail/u-boot and
66 http://dir.gmane.org/gmane.comp.boot-loaders.u-boot
69 Where to get source code:
70 =========================
72 The U-Boot source code is maintained in the git repository at
73 git://www.denx.de/git/u-boot.git ; you can browse it online at
74 http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary
76 The "snapshot" links on this page allow you to download tarballs of
77 any version you might be interested in. Official releases are also
78 available for FTP download from the ftp://ftp.denx.de/pub/u-boot/
81 Pre-built (and tested) images are available from
82 ftp://ftp.denx.de/pub/u-boot/images/
88 - start from 8xxrom sources
89 - create PPCBoot project (http://sourceforge.net/projects/ppcboot)
91 - make it easier to add custom boards
92 - make it possible to add other [PowerPC] CPUs
93 - extend functions, especially:
94 * Provide extended interface to Linux boot loader
97 * PCMCIA / CompactFlash / ATA disk / SCSI ... boot
98 - create ARMBoot project (http://sourceforge.net/projects/armboot)
99 - add other CPU families (starting with ARM)
100 - create U-Boot project (http://sourceforge.net/projects/u-boot)
101 - current project page: see http://www.denx.de/wiki/U-Boot
107 The "official" name of this project is "Das U-Boot". The spelling
108 "U-Boot" shall be used in all written text (documentation, comments
109 in source files etc.). Example:
111 This is the README file for the U-Boot project.
113 File names etc. shall be based on the string "u-boot". Examples:
115 include/asm-ppc/u-boot.h
117 #include <asm/u-boot.h>
119 Variable names, preprocessor constants etc. shall be either based on
120 the string "u_boot" or on "U_BOOT". Example:
122 U_BOOT_VERSION u_boot_logo
123 IH_OS_U_BOOT u_boot_hush_start
129 U-Boot uses a 3 level version number containing a version, a
130 sub-version, and a patchlevel: "U-Boot-2.34.5" means version "2",
131 sub-version "34", and patchlevel "4".
133 The patchlevel is used to indicate certain stages of development
134 between released versions, i. e. officially released versions of
135 U-Boot will always have a patchlevel of "0".
141 - board Board dependent files
142 - common Misc architecture independent functions
143 - cpu CPU specific files
144 - 74xx_7xx Files specific to Freescale MPC74xx and 7xx CPUs
145 - arm720t Files specific to ARM 720 CPUs
146 - arm920t Files specific to ARM 920 CPUs
147 - at91rm9200 Files specific to Atmel AT91RM9200 CPU
148 - imx Files specific to Freescale MC9328 i.MX CPUs
149 - s3c24x0 Files specific to Samsung S3C24X0 CPUs
150 - arm925t Files specific to ARM 925 CPUs
151 - arm926ejs Files specific to ARM 926 CPUs
152 - arm1136 Files specific to ARM 1136 CPUs
153 - at32ap Files specific to Atmel AVR32 AP CPUs
154 - blackfin Files specific to Analog Devices Blackfin CPUs
155 - i386 Files specific to i386 CPUs
156 - ixp Files specific to Intel XScale IXP CPUs
157 - leon2 Files specific to Gaisler LEON2 SPARC CPU
158 - leon3 Files specific to Gaisler LEON3 SPARC CPU
159 - mcf52x2 Files specific to Freescale ColdFire MCF52x2 CPUs
160 - mcf5227x Files specific to Freescale ColdFire MCF5227x CPUs
161 - mcf532x Files specific to Freescale ColdFire MCF5329 CPUs
162 - mcf5445x Files specific to Freescale ColdFire MCF5445x CPUs
163 - mcf547x_8x Files specific to Freescale ColdFire MCF547x_8x CPUs
164 - mips Files specific to MIPS CPUs
165 - mpc5xx Files specific to Freescale MPC5xx CPUs
166 - mpc5xxx Files specific to Freescale MPC5xxx CPUs
167 - mpc8xx Files specific to Freescale MPC8xx CPUs
168 - mpc8220 Files specific to Freescale MPC8220 CPUs
169 - mpc824x Files specific to Freescale MPC824x CPUs
170 - mpc8260 Files specific to Freescale MPC8260 CPUs
171 - mpc85xx Files specific to Freescale MPC85xx CPUs
172 - nios Files specific to Altera NIOS CPUs
173 - nios2 Files specific to Altera Nios-II CPUs
174 - ppc4xx Files specific to AMCC PowerPC 4xx CPUs
175 - pxa Files specific to Intel XScale PXA CPUs
176 - s3c44b0 Files specific to Samsung S3C44B0 CPUs
177 - sa1100 Files specific to Intel StrongARM SA1100 CPUs
178 - disk Code for disk drive partition handling
179 - doc Documentation (don't expect too much)
180 - drivers Commonly used device drivers
181 - dtt Digital Thermometer and Thermostat drivers
182 - examples Example code for standalone applications, etc.
183 - include Header Files
184 - lib_arm Files generic to ARM architecture
185 - lib_avr32 Files generic to AVR32 architecture
186 - lib_blackfin Files generic to Blackfin architecture
187 - lib_generic Files generic to all architectures
188 - lib_i386 Files generic to i386 architecture
189 - lib_m68k Files generic to m68k architecture
190 - lib_mips Files generic to MIPS architecture
191 - lib_nios Files generic to NIOS architecture
192 - lib_ppc Files generic to PowerPC architecture
193 - lib_sparc Files generic to SPARC architecture
194 - libfdt Library files to support flattened device trees
195 - net Networking code
196 - post Power On Self Test
197 - rtc Real Time Clock drivers
198 - tools Tools to build S-Record or U-Boot images, etc.
200 Software Configuration:
201 =======================
203 Configuration is usually done using C preprocessor defines; the
204 rationale behind that is to avoid dead code whenever possible.
206 There are two classes of configuration variables:
208 * Configuration _OPTIONS_:
209 These are selectable by the user and have names beginning with
212 * Configuration _SETTINGS_:
213 These depend on the hardware etc. and should not be meddled with if
214 you don't know what you're doing; they have names beginning with
217 Later we will add a configuration tool - probably similar to or even
218 identical to what's used for the Linux kernel. Right now, we have to
219 do the configuration by hand, which means creating some symbolic
220 links and editing some configuration files. We use the TQM8xxL boards
224 Selection of Processor Architecture and Board Type:
225 ---------------------------------------------------
227 For all supported boards there are ready-to-use default
228 configurations available; just type "make <board_name>_config".
230 Example: For a TQM823L module type:
235 For the Cogent platform, you need to specify the CPU type as well;
236 e.g. "make cogent_mpc8xx_config". And also configure the cogent
237 directory according to the instructions in cogent/README.
240 Configuration Options:
241 ----------------------
243 Configuration depends on the combination of board and CPU type; all
244 such information is kept in a configuration file
245 "include/configs/<board_name>.h".
247 Example: For a TQM823L module, all configuration settings are in
248 "include/configs/TQM823L.h".
251 Many of the options are named exactly as the corresponding Linux
252 kernel configuration options. The intention is to make it easier to
253 build a config tool - later.
256 The following options need to be configured:
258 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
260 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
262 - CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
263 Define exactly one, e.g. CONFIG_ATSTK1002
265 - CPU Module Type: (if CONFIG_COGENT is defined)
266 Define exactly one of
268 --- FIXME --- not tested yet:
269 CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,
270 CONFIG_CMA287_23, CONFIG_CMA287_50
272 - Motherboard Type: (if CONFIG_COGENT is defined)
273 Define exactly one of
274 CONFIG_CMA101, CONFIG_CMA102
276 - Motherboard I/O Modules: (if CONFIG_COGENT is defined)
277 Define one or more of
280 - Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)
281 Define one or more of
282 CONFIG_LCD_HEARTBEAT - update a character position on
283 the LCD display every second with
286 - Board flavour: (if CONFIG_MPC8260ADS is defined)
289 CONFIG_SYS_8260ADS - original MPC8260ADS
290 CONFIG_SYS_8266ADS - MPC8266ADS
291 CONFIG_SYS_PQ2FADS - PQ2FADS-ZU or PQ2FADS-VR
292 CONFIG_SYS_8272ADS - MPC8272ADS
294 - MPC824X Family Member (if CONFIG_MPC824X is defined)
295 Define exactly one of
296 CONFIG_MPC8240, CONFIG_MPC8245
298 - 8xx CPU Options: (if using an MPC8xx CPU)
299 CONFIG_8xx_GCLK_FREQ - deprecated: CPU clock if
300 get_gclk_freq() cannot work
301 e.g. if there is no 32KHz
302 reference PIT/RTC clock
303 CONFIG_8xx_OSCLK - PLL input clock (either EXTCLK
306 - 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):
307 CONFIG_SYS_8xx_CPUCLK_MIN
308 CONFIG_SYS_8xx_CPUCLK_MAX
309 CONFIG_8xx_CPUCLK_DEFAULT
310 See doc/README.MPC866
312 CONFIG_SYS_MEASURE_CPUCLK
314 Define this to measure the actual CPU clock instead
315 of relying on the correctness of the configured
316 values. Mostly useful for board bringup to make sure
317 the PLL is locked at the intended frequency. Note
318 that this requires a (stable) reference clock (32 kHz
319 RTC clock or CONFIG_SYS_8XX_XIN)
321 - Intel Monahans options:
322 CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO
324 Defines the Monahans run mode to oscillator
325 ratio. Valid values are 8, 16, 24, 31. The core
326 frequency is this value multiplied by 13 MHz.
328 CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO
330 Defines the Monahans turbo mode to oscillator
331 ratio. Valid values are 1 (default if undefined) and
332 2. The core frequency as calculated above is multiplied
335 - Linux Kernel Interface:
338 U-Boot stores all clock information in Hz
339 internally. For binary compatibility with older Linux
340 kernels (which expect the clocks passed in the
341 bd_info data to be in MHz) the environment variable
342 "clocks_in_mhz" can be defined so that U-Boot
343 converts clock data to MHZ before passing it to the
345 When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
346 "clocks_in_mhz=1" is automatically included in the
349 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
351 When transferring memsize parameter to linux, some versions
352 expect it to be in bytes, others in MB.
353 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
357 New kernel versions are expecting firmware settings to be
358 passed using flattened device trees (based on open firmware
362 * New libfdt-based support
363 * Adds the "fdt" command
364 * The bootm command automatically updates the fdt
366 OF_CPU - The proper name of the cpus node.
367 OF_SOC - The proper name of the soc node.
368 OF_TBCLK - The timebase frequency.
369 OF_STDOUT_PATH - The path to the console device
371 boards with QUICC Engines require OF_QE to set UCC MAC
374 CONFIG_OF_BOARD_SETUP
376 Board code has addition modification that it wants to make
377 to the flat device tree before handing it off to the kernel
381 This define fills in the correct boot CPU in the boot
382 param header, the default value is zero if undefined.
387 Define this if you want support for Amba PrimeCell PL010 UARTs.
391 Define this if you want support for Amba PrimeCell PL011 UARTs.
395 If you have Amba PrimeCell PL011 UARTs, set this variable to
396 the clock speed of the UARTs.
400 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
401 define this to a list of base addresses for each (supported)
402 port. See e.g. include/configs/versatile.h
406 Depending on board, define exactly one serial port
407 (like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
408 CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
409 console by defining CONFIG_8xx_CONS_NONE
411 Note: if CONFIG_8xx_CONS_NONE is defined, the serial
412 port routines must be defined elsewhere
413 (i.e. serial_init(), serial_getc(), ...)
416 Enables console device for a color framebuffer. Needs following
417 defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
418 VIDEO_FB_LITTLE_ENDIAN graphic memory organisation
420 VIDEO_HW_RECTFILL graphic chip supports
423 VIDEO_HW_BITBLT graphic chip supports
424 bit-blit (cf. smiLynxEM)
425 VIDEO_VISIBLE_COLS visible pixel columns
427 VIDEO_VISIBLE_ROWS visible pixel rows
428 VIDEO_PIXEL_SIZE bytes per pixel
429 VIDEO_DATA_FORMAT graphic data format
430 (0-5, cf. cfb_console.c)
431 VIDEO_FB_ADRS framebuffer address
432 VIDEO_KBD_INIT_FCT keyboard int fct
433 (i.e. i8042_kbd_init())
434 VIDEO_TSTC_FCT test char fct
436 VIDEO_GETC_FCT get char fct
438 CONFIG_CONSOLE_CURSOR cursor drawing on/off
439 (requires blink timer
441 CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
442 CONFIG_CONSOLE_TIME display time/date info in
444 (requires CONFIG_CMD_DATE)
445 CONFIG_VIDEO_LOGO display Linux logo in
447 CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of
448 linux_logo.h for logo.
449 Requires CONFIG_VIDEO_LOGO
450 CONFIG_CONSOLE_EXTRA_INFO
451 additional board info beside
454 When CONFIG_CFB_CONSOLE is defined, video console is
455 default i/o. Serial console can be forced with
456 environment 'console=serial'.
458 When CONFIG_SILENT_CONSOLE is defined, all console
459 messages (by U-Boot and Linux!) can be silenced with
460 the "silent" environment variable. See
461 doc/README.silent for more information.
464 CONFIG_BAUDRATE - in bps
465 Select one of the baudrates listed in
466 CONFIG_SYS_BAUDRATE_TABLE, see below.
467 CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale
469 - Interrupt driven serial port input:
470 CONFIG_SERIAL_SOFTWARE_FIFO
473 Use an interrupt handler for receiving data on the
474 serial port. It also enables using hardware handshake
475 (RTS/CTS) and UART's built-in FIFO. Set the number of
476 bytes the interrupt driven input buffer should have.
478 Leave undefined to disable this feature, including
479 disable the buffer and hardware handshake.
481 - Console UART Number:
485 If defined internal UART1 (and not UART0) is used
486 as default U-Boot console.
488 - Boot Delay: CONFIG_BOOTDELAY - in seconds
489 Delay before automatically booting the default image;
490 set to -1 to disable autoboot.
492 See doc/README.autoboot for these options that
493 work with CONFIG_BOOTDELAY. None are required.
494 CONFIG_BOOT_RETRY_TIME
495 CONFIG_BOOT_RETRY_MIN
496 CONFIG_AUTOBOOT_KEYED
497 CONFIG_AUTOBOOT_PROMPT
498 CONFIG_AUTOBOOT_DELAY_STR
499 CONFIG_AUTOBOOT_STOP_STR
500 CONFIG_AUTOBOOT_DELAY_STR2
501 CONFIG_AUTOBOOT_STOP_STR2
502 CONFIG_ZERO_BOOTDELAY_CHECK
503 CONFIG_RESET_TO_RETRY
507 Only needed when CONFIG_BOOTDELAY is enabled;
508 define a command string that is automatically executed
509 when no character is read on the console interface
510 within "Boot Delay" after reset.
513 This can be used to pass arguments to the bootm
514 command. The value of CONFIG_BOOTARGS goes into the
515 environment value "bootargs".
517 CONFIG_RAMBOOT and CONFIG_NFSBOOT
518 The value of these goes into the environment as
519 "ramboot" and "nfsboot" respectively, and can be used
520 as a convenience, when switching between booting from
526 When this option is #defined, the existence of the
527 environment variable "preboot" will be checked
528 immediately before starting the CONFIG_BOOTDELAY
529 countdown and/or running the auto-boot command resp.
530 entering interactive mode.
532 This feature is especially useful when "preboot" is
533 automatically generated or modified. For an example
534 see the LWMON board specific code: here "preboot" is
535 modified when the user holds down a certain
536 combination of keys on the (special) keyboard when
539 - Serial Download Echo Mode:
541 If defined to 1, all characters received during a
542 serial download (using the "loads" command) are
543 echoed back. This might be needed by some terminal
544 emulations (like "cu"), but may as well just take
545 time on others. This setting #define's the initial
546 value of the "loads_echo" environment variable.
548 - Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)
550 Select one of the baudrates listed in
551 CONFIG_SYS_BAUDRATE_TABLE, see below.
554 Monitor commands can be included or excluded
555 from the build by using the #include files
556 "config_cmd_all.h" and #undef'ing unwanted
557 commands, or using "config_cmd_default.h"
558 and augmenting with additional #define's
561 The default command configuration includes all commands
562 except those marked below with a "*".
564 CONFIG_CMD_ASKENV * ask for env variable
565 CONFIG_CMD_AUTOSCRIPT Autoscript Support
566 CONFIG_CMD_BDI bdinfo
567 CONFIG_CMD_BEDBUG * Include BedBug Debugger
568 CONFIG_CMD_BMP * BMP support
569 CONFIG_CMD_BSP * Board specific commands
570 CONFIG_CMD_BOOTD bootd
571 CONFIG_CMD_CACHE * icache, dcache
572 CONFIG_CMD_CONSOLE coninfo
573 CONFIG_CMD_DATE * support for RTC, date/time...
574 CONFIG_CMD_DHCP * DHCP support
575 CONFIG_CMD_DIAG * Diagnostics
576 CONFIG_CMD_DOC * Disk-On-Chip Support
577 CONFIG_CMD_DTT * Digital Therm and Thermostat
578 CONFIG_CMD_ECHO echo arguments
579 CONFIG_CMD_EEPROM * EEPROM read/write support
580 CONFIG_CMD_ELF * bootelf, bootvx
581 CONFIG_CMD_ENV saveenv
582 CONFIG_CMD_FDC * Floppy Disk Support
583 CONFIG_CMD_FAT * FAT partition support
584 CONFIG_CMD_FDOS * Dos diskette Support
585 CONFIG_CMD_FLASH flinfo, erase, protect
586 CONFIG_CMD_FPGA FPGA device initialization support
587 CONFIG_CMD_HWFLOW * RTS/CTS hw flow control
588 CONFIG_CMD_I2C * I2C serial bus support
589 CONFIG_CMD_IDE * IDE harddisk support
590 CONFIG_CMD_IMI iminfo
591 CONFIG_CMD_IMLS List all found images
592 CONFIG_CMD_IMMAP * IMMR dump support
593 CONFIG_CMD_IRQ * irqinfo
594 CONFIG_CMD_ITEST Integer/string test of 2 values
595 CONFIG_CMD_JFFS2 * JFFS2 Support
596 CONFIG_CMD_KGDB * kgdb
597 CONFIG_CMD_LOADB loadb
598 CONFIG_CMD_LOADS loads
599 CONFIG_CMD_MEMORY md, mm, nm, mw, cp, cmp, crc, base,
601 CONFIG_CMD_MISC Misc functions like sleep etc
602 CONFIG_CMD_MMC * MMC memory mapped support
603 CONFIG_CMD_MII * MII utility commands
604 CONFIG_CMD_NAND * NAND support
605 CONFIG_CMD_NET bootp, tftpboot, rarpboot
606 CONFIG_CMD_PCI * pciinfo
607 CONFIG_CMD_PCMCIA * PCMCIA support
608 CONFIG_CMD_PING * send ICMP ECHO_REQUEST to network
610 CONFIG_CMD_PORTIO * Port I/O
611 CONFIG_CMD_REGINFO * Register dump
612 CONFIG_CMD_RUN run command in env variable
613 CONFIG_CMD_SAVES * save S record dump
614 CONFIG_CMD_SCSI * SCSI Support
615 CONFIG_CMD_SDRAM * print SDRAM configuration information
616 (requires CONFIG_CMD_I2C)
617 CONFIG_CMD_SETGETDCR Support for DCR Register access
619 CONFIG_CMD_SPI * SPI serial bus support
620 CONFIG_CMD_USB * USB support
621 CONFIG_CMD_VFD * VFD support (TRAB)
622 CONFIG_CMD_CDP * Cisco Discover Protocol support
623 CONFIG_CMD_FSL * Microblaze FSL support
626 EXAMPLE: If you want all functions except of network
627 support you can write:
629 #include "config_cmd_all.h"
630 #undef CONFIG_CMD_NET
633 fdt (flattened device tree) command: CONFIG_OF_LIBFDT
635 Note: Don't enable the "icache" and "dcache" commands
636 (configuration option CONFIG_CMD_CACHE) unless you know
637 what you (and your U-Boot users) are doing. Data
638 cache cannot be enabled on systems like the 8xx or
639 8260 (where accesses to the IMMR region must be
640 uncached), and it cannot be disabled on all other
641 systems where we (mis-) use the data cache to hold an
642 initial stack and some data.
645 XXX - this list needs to get updated!
649 If this variable is defined, it enables watchdog
650 support. There must be support in the platform specific
651 code for a watchdog. For the 8xx and 8260 CPUs, the
652 SIU Watchdog feature is enabled in the SYPCR
656 CONFIG_VERSION_VARIABLE
657 If this variable is defined, an environment variable
658 named "ver" is created by U-Boot showing the U-Boot
659 version as printed by the "version" command.
660 This variable is readonly.
664 When CONFIG_CMD_DATE is selected, the type of the RTC
665 has to be selected, too. Define exactly one of the
668 CONFIG_RTC_MPC8xx - use internal RTC of MPC8xx
669 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
670 CONFIG_RTC_MC13783 - use MC13783 RTC
671 CONFIG_RTC_MC146818 - use MC146818 RTC
672 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
673 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
674 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
675 CONFIG_RTC_DS164x - use Dallas DS164x RTC
676 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
677 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
678 CONFIG_SYS_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
680 Note that if the RTC uses I2C, then the I2C interface
681 must also be configured. See I2C Support, below.
685 When CONFIG_TIMESTAMP is selected, the timestamp
686 (date and time) of an image is printed by image
687 commands like bootm or iminfo. This option is
688 automatically enabled when you select CONFIG_CMD_DATE .
691 CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
692 and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION
694 If IDE or SCSI support is enabled (CONFIG_CMD_IDE or
695 CONFIG_CMD_SCSI) you must configure support for at
696 least one partition type as well.
699 CONFIG_IDE_RESET_ROUTINE - this is defined in several
700 board configurations files but used nowhere!
702 CONFIG_IDE_RESET - is this is defined, IDE Reset will
703 be performed by calling the function
704 ide_set_reset(int reset)
705 which has to be defined in a board specific file
710 Set this to enable ATAPI support.
715 Set this to enable support for disks larger than 137GB
716 Also look at CONFIG_SYS_64BIT_LBA ,CONFIG_SYS_64BIT_VSPRINTF and CONFIG_SYS_64BIT_STRTOUL
717 Whithout these , LBA48 support uses 32bit variables and will 'only'
718 support disks up to 2.1TB.
720 CONFIG_SYS_64BIT_LBA:
721 When enabled, makes the IDE subsystem use 64bit sector addresses.
725 At the moment only there is only support for the
726 SYM53C8XX SCSI controller; define
727 CONFIG_SCSI_SYM53C8XX to enable it.
729 CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
730 CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
731 CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
732 maximum numbers of LUNs, SCSI ID's and target
734 CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)
736 - NETWORK Support (PCI):
738 Support for Intel 8254x gigabit chips.
740 CONFIG_E1000_FALLBACK_MAC
741 default MAC for empty EEPROM after production.
744 Support for Intel 82557/82559/82559ER chips.
745 Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM
746 write routine for first time initialisation.
749 Support for Digital 2114x chips.
750 Optional CONFIG_TULIP_SELECT_MEDIA for board specific
751 modem chip initialisation (KS8761/QS6611).
754 Support for National dp83815 chips.
757 Support for National dp8382[01] gigabit chips.
759 - NETWORK Support (other):
761 CONFIG_DRIVER_LAN91C96
762 Support for SMSC's LAN91C96 chips.
765 Define this to hold the physical address
766 of the LAN91C96's I/O space
768 CONFIG_LAN91C96_USE_32_BIT
769 Define this to enable 32 bit addressing
771 CONFIG_DRIVER_SMC91111
772 Support for SMSC's LAN91C111 chip
775 Define this to hold the physical address
776 of the device (I/O space)
778 CONFIG_SMC_USE_32_BIT
779 Define this if data bus is 32 bits
781 CONFIG_SMC_USE_IOFUNCS
782 Define this to use i/o functions instead of macros
783 (some hardware wont work with macros)
785 CONFIG_DRIVER_SMC911X
786 Support for SMSC's LAN911x and LAN921x chips
788 CONFIG_DRIVER_SMC911X_BASE
789 Define this to hold the physical address
790 of the device (I/O space)
792 CONFIG_DRIVER_SMC911X_32_BIT
793 Define this if data bus is 32 bits
795 CONFIG_DRIVER_SMC911X_16_BIT
796 Define this if data bus is 16 bits. If your processor
797 automatically converts one 32 bit word to two 16 bit
798 words you may also try CONFIG_DRIVER_SMC911X_32_BIT.
801 At the moment only the UHCI host controller is
802 supported (PIP405, MIP405, MPC5200); define
803 CONFIG_USB_UHCI to enable it.
804 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
805 and define CONFIG_USB_STORAGE to enable the USB
808 Supported are USB Keyboards and USB Floppy drives
810 MPC5200 USB requires additional defines:
812 for 528 MHz Clock: 0x0001bbbb
814 for differential drivers: 0x00001000
815 for single ended drivers: 0x00005000
816 CONFIG_SYS_USB_EVENT_POLL
817 May be defined to allow interrupt polling
818 instead of using asynchronous interrupts
821 Define the below if you wish to use the USB console.
822 Once firmware is rebuilt from a serial console issue the
823 command "setenv stdin usbtty; setenv stdout usbtty" and
824 attach your USB cable. The Unix command "dmesg" should print
825 it has found a new device. The environment variable usbtty
826 can be set to gserial or cdc_acm to enable your device to
827 appear to a USB host as a Linux gserial device or a
828 Common Device Class Abstract Control Model serial device.
829 If you select usbtty = gserial you should be able to enumerate
831 # modprobe usbserial vendor=0xVendorID product=0xProductID
832 else if using cdc_acm, simply setting the environment
833 variable usbtty to be cdc_acm should suffice. The following
834 might be defined in YourBoardName.h
837 Define this to build a UDC device
840 Define this to have a tty type of device available to
841 talk to the UDC device
843 CONFIG_SYS_CONSOLE_IS_IN_ENV
844 Define this if you want stdin, stdout &/or stderr to
848 CONFIG_SYS_USB_EXTC_CLK 0xBLAH
849 Derive USB clock from external clock "blah"
850 - CONFIG_SYS_USB_EXTC_CLK 0x02
852 CONFIG_SYS_USB_BRG_CLK 0xBLAH
853 Derive USB clock from brgclk
854 - CONFIG_SYS_USB_BRG_CLK 0x04
856 If you have a USB-IF assigned VendorID then you may wish to
857 define your own vendor specific values either in BoardName.h
858 or directly in usbd_vendor_info.h. If you don't define
859 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
860 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
861 should pretend to be a Linux device to it's target host.
863 CONFIG_USBD_MANUFACTURER
864 Define this string as the name of your company for
865 - CONFIG_USBD_MANUFACTURER "my company"
867 CONFIG_USBD_PRODUCT_NAME
868 Define this string as the name of your product
869 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
872 Define this as your assigned Vendor ID from the USB
873 Implementors Forum. This *must* be a genuine Vendor ID
874 to avoid polluting the USB namespace.
875 - CONFIG_USBD_VENDORID 0xFFFF
877 CONFIG_USBD_PRODUCTID
878 Define this as the unique Product ID
880 - CONFIG_USBD_PRODUCTID 0xFFFF
884 The MMC controller on the Intel PXA is supported. To
885 enable this define CONFIG_MMC. The MMC can be
886 accessed from the boot prompt by mapping the device
887 to physical memory similar to flash. Command line is
888 enabled with CONFIG_CMD_MMC. The MMC driver also works with
889 the FAT fs. This is enabled with CONFIG_CMD_FAT.
891 - Journaling Flash filesystem support:
892 CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,
893 CONFIG_JFFS2_NAND_DEV
894 Define these for a default partition on a NAND device
896 CONFIG_SYS_JFFS2_FIRST_SECTOR,
897 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
898 Define these for a default partition on a NOR device
900 CONFIG_SYS_JFFS_CUSTOM_PART
901 Define this to create an own partition. You have to provide a
902 function struct part_info* jffs2_part_info(int part_num)
904 If you define only one JFFS2 partition you may also want to
905 #define CONFIG_SYS_JFFS_SINGLE_PART 1
906 to disable the command chpart. This is the default when you
907 have not defined a custom partition
912 Define this to enable standard (PC-Style) keyboard
916 Standard PC keyboard driver with US (is default) and
917 GERMAN key layout (switch via environment 'keymap=de') support.
918 Export function i8042_kbd_init, i8042_tstc and i8042_getc
919 for cfb_console. Supports cursor blinking.
924 Define this to enable video support (for output to
929 Enable Chips & Technologies 69000 Video chip
931 CONFIG_VIDEO_SMI_LYNXEM
932 Enable Silicon Motion SMI 712/710/810 Video chip. The
933 video output is selected via environment 'videoout'
934 (1 = LCD and 2 = CRT). If videoout is undefined, CRT is
937 For the CT69000 and SMI_LYNXEM drivers, videomode is
938 selected via environment 'videomode'. Two different ways
940 - "videomode=num" 'num' is a standard LiLo mode numbers.
941 Following standard modes are supported (* is default):
943 Colors 640x480 800x600 1024x768 1152x864 1280x1024
944 -------------+---------------------------------------------
945 8 bits | 0x301* 0x303 0x305 0x161 0x307
946 15 bits | 0x310 0x313 0x316 0x162 0x319
947 16 bits | 0x311 0x314 0x317 0x163 0x31A
948 24 bits | 0x312 0x315 0x318 ? 0x31B
949 -------------+---------------------------------------------
950 (i.e. setenv videomode 317; saveenv; reset;)
952 - "videomode=bootargs" all the video parameters are parsed
953 from the bootargs. (See drivers/video/videomodes.c)
956 CONFIG_VIDEO_SED13806
957 Enable Epson SED13806 driver. This driver supports 8bpp
958 and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP
959 or CONFIG_VIDEO_SED13806_16BPP
964 Define this to enable a custom keyboard support.
965 This simply calls drv_keyboard_init() which must be
966 defined in your board-specific files.
967 The only board using this so far is RBC823.
969 - LCD Support: CONFIG_LCD
971 Define this to enable LCD support (for output to LCD
972 display); also select one of the supported displays
973 by defining one of these:
977 HITACHI TX09D70VM1CCA, 3.5", 240x320.
979 CONFIG_NEC_NL6448AC33:
981 NEC NL6448AC33-18. Active, color, single scan.
983 CONFIG_NEC_NL6448BC20
985 NEC NL6448BC20-08. 6.5", 640x480.
986 Active, color, single scan.
988 CONFIG_NEC_NL6448BC33_54
990 NEC NL6448BC33-54. 10.4", 640x480.
991 Active, color, single scan.
995 Sharp 320x240. Active, color, single scan.
996 It isn't 16x9, and I am not sure what it is.
998 CONFIG_SHARP_LQ64D341
1000 Sharp LQ64D341 display, 640x480.
1001 Active, color, single scan.
1005 HLD1045 display, 640x480.
1006 Active, color, single scan.
1010 Optrex CBL50840-2 NF-FW 99 22 M5
1012 Hitachi LMG6912RPFC-00T
1016 320x240. Black & white.
1018 Normally display is black on white background; define
1019 CONFIG_SYS_WHITE_ON_BLACK to get it inverted.
1021 - Splash Screen Support: CONFIG_SPLASH_SCREEN
1023 If this option is set, the environment is checked for
1024 a variable "splashimage". If found, the usual display
1025 of logo, copyright and system information on the LCD
1026 is suppressed and the BMP image at the address
1027 specified in "splashimage" is loaded instead. The
1028 console is redirected to the "nulldev", too. This
1029 allows for a "silent" boot where a splash screen is
1030 loaded very quickly after power-on.
1032 - Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP
1034 If this option is set, additionally to standard BMP
1035 images, gzipped BMP images can be displayed via the
1036 splashscreen support or the bmp command.
1038 - Compression support:
1041 If this option is set, support for bzip2 compressed
1042 images is included. If not, only uncompressed and gzip
1043 compressed images are supported.
1045 NOTE: the bzip2 algorithm requires a lot of RAM, so
1046 the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should
1051 If this option is set, support for lzma compressed
1054 Note: The LZMA algorithm adds between 2 and 4KB of code and it
1055 requires an amount of dynamic memory that is given by the
1058 (1846 + 768 << (lc + lp)) * sizeof(uint16)
1060 Where lc and lp stand for, respectively, Literal context bits
1061 and Literal pos bits.
1063 This value is upper-bounded by 14MB in the worst case. Anyway,
1064 for a ~4MB large kernel image, we have lc=3 and lp=0 for a
1065 total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is
1066 a very small buffer.
1068 Use the lzmainfo tool to determinate the lc and lp values and
1069 then calculate the amount of needed dynamic memory (ensuring
1070 the appropriate CONFIG_SYS_MALLOC_LEN value).
1075 The address of PHY on MII bus.
1077 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1079 The clock frequency of the MII bus
1083 If this option is set, support for speed/duplex
1084 detection of gigabit PHY is included.
1086 CONFIG_PHY_RESET_DELAY
1088 Some PHY like Intel LXT971A need extra delay after
1089 reset before any MII register access is possible.
1090 For such PHY, set this option to the usec delay
1091 required. (minimum 300usec for LXT971A)
1093 CONFIG_PHY_CMD_DELAY (ppc4xx)
1095 Some PHY like Intel LXT971A need extra delay after
1096 command issued before MII status register can be read
1106 Define a default value for Ethernet address to use
1107 for the respective Ethernet interface, in case this
1108 is not determined automatically.
1113 Define a default value for the IP address to use for
1114 the default Ethernet interface, in case this is not
1115 determined through e.g. bootp.
1117 - Server IP address:
1120 Defines a default value for the IP address of a TFTP
1121 server to contact when using the "tftboot" command.
1123 - Multicast TFTP Mode:
1126 Defines whether you want to support multicast TFTP as per
1127 rfc-2090; for example to work with atftp. Lets lots of targets
1128 tftp down the same boot image concurrently. Note: the Ethernet
1129 driver in use must provide a function: mcast() to join/leave a
1132 CONFIG_BOOTP_RANDOM_DELAY
1133 - BOOTP Recovery Mode:
1134 CONFIG_BOOTP_RANDOM_DELAY
1136 If you have many targets in a network that try to
1137 boot using BOOTP, you may want to avoid that all
1138 systems send out BOOTP requests at precisely the same
1139 moment (which would happen for instance at recovery
1140 from a power failure, when all systems will try to
1141 boot, thus flooding the BOOTP server. Defining
1142 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1143 inserted before sending out BOOTP requests. The
1144 following delays are inserted then:
1146 1st BOOTP request: delay 0 ... 1 sec
1147 2nd BOOTP request: delay 0 ... 2 sec
1148 3rd BOOTP request: delay 0 ... 4 sec
1150 BOOTP requests: delay 0 ... 8 sec
1152 - DHCP Advanced Options:
1153 You can fine tune the DHCP functionality by defining
1154 CONFIG_BOOTP_* symbols:
1156 CONFIG_BOOTP_SUBNETMASK
1157 CONFIG_BOOTP_GATEWAY
1158 CONFIG_BOOTP_HOSTNAME
1159 CONFIG_BOOTP_NISDOMAIN
1160 CONFIG_BOOTP_BOOTPATH
1161 CONFIG_BOOTP_BOOTFILESIZE
1164 CONFIG_BOOTP_SEND_HOSTNAME
1165 CONFIG_BOOTP_NTPSERVER
1166 CONFIG_BOOTP_TIMEOFFSET
1167 CONFIG_BOOTP_VENDOREX
1169 CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
1170 environment variable, not the BOOTP server.
1172 CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS
1173 serverip from a DHCP server, it is possible that more
1174 than one DNS serverip is offered to the client.
1175 If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS
1176 serverip will be stored in the additional environment
1177 variable "dnsip2". The first DNS serverip is always
1178 stored in the variable "dnsip", when CONFIG_BOOTP_DNS
1181 CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable
1182 to do a dynamic update of a DNS server. To do this, they
1183 need the hostname of the DHCP requester.
1184 If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content
1185 of the "hostname" environment variable is passed as
1186 option 12 to the DHCP server.
1188 CONFIG_BOOTP_DHCP_REQUEST_DELAY
1190 A 32bit value in microseconds for a delay between
1191 receiving a "DHCP Offer" and sending the "DHCP Request".
1192 This fixes a problem with certain DHCP servers that don't
1193 respond 100% of the time to a "DHCP request". E.g. On an
1194 AT91RM9200 processor running at 180MHz, this delay needed
1195 to be *at least* 15,000 usec before a Windows Server 2003
1196 DHCP server would reply 100% of the time. I recommend at
1197 least 50,000 usec to be safe. The alternative is to hope
1198 that one of the retries will be successful but note that
1199 the DHCP timeout and retry process takes a longer than
1203 CONFIG_CDP_DEVICE_ID
1205 The device id used in CDP trigger frames.
1207 CONFIG_CDP_DEVICE_ID_PREFIX
1209 A two character string which is prefixed to the MAC address
1214 A printf format string which contains the ascii name of
1215 the port. Normally is set to "eth%d" which sets
1216 eth0 for the first Ethernet, eth1 for the second etc.
1218 CONFIG_CDP_CAPABILITIES
1220 A 32bit integer which indicates the device capabilities;
1221 0x00000010 for a normal host which does not forwards.
1225 An ascii string containing the version of the software.
1229 An ascii string containing the name of the platform.
1233 A 32bit integer sent on the trigger.
1235 CONFIG_CDP_POWER_CONSUMPTION
1237 A 16bit integer containing the power consumption of the
1238 device in .1 of milliwatts.
1240 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1242 A byte containing the id of the VLAN.
1244 - Status LED: CONFIG_STATUS_LED
1246 Several configurations allow to display the current
1247 status using a LED. For instance, the LED will blink
1248 fast while running U-Boot code, stop blinking as
1249 soon as a reply to a BOOTP request was received, and
1250 start blinking slow once the Linux kernel is running
1251 (supported by a status LED driver in the Linux
1252 kernel). Defining CONFIG_STATUS_LED enables this
1255 - CAN Support: CONFIG_CAN_DRIVER
1257 Defining CONFIG_CAN_DRIVER enables CAN driver support
1258 on those systems that support this (optional)
1259 feature, like the TQM8xxL modules.
1261 - I2C Support: CONFIG_HARD_I2C | CONFIG_SOFT_I2C
1263 These enable I2C serial bus commands. Defining either of
1264 (but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will
1265 include the appropriate I2C driver for the selected CPU.
1267 This will allow you to use i2c commands at the u-boot
1268 command line (as long as you set CONFIG_CMD_I2C in
1269 CONFIG_COMMANDS) and communicate with i2c based realtime
1270 clock chips. See common/cmd_i2c.c for a description of the
1271 command line interface.
1273 CONFIG_I2C_CMD_TREE is a recommended option that places
1274 all I2C commands under a single 'i2c' root command. The
1275 older 'imm', 'imd', 'iprobe' etc. commands are considered
1276 deprecated and may disappear in the future.
1278 CONFIG_HARD_I2C selects a hardware I2C controller.
1280 CONFIG_SOFT_I2C configures u-boot to use a software (aka
1281 bit-banging) driver instead of CPM or similar hardware
1284 There are several other quantities that must also be
1285 defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.
1287 In both cases you will need to define CONFIG_SYS_I2C_SPEED
1288 to be the frequency (in Hz) at which you wish your i2c bus
1289 to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie
1290 the CPU's i2c node address).
1292 Now, the u-boot i2c code for the mpc8xx (cpu/mpc8xx/i2c.c)
1293 sets the CPU up as a master node and so its address should
1294 therefore be cleared to 0 (See, eg, MPC823e User's Manual
1295 p.16-473). So, set CONFIG_SYS_I2C_SLAVE to 0.
1297 That's all that's required for CONFIG_HARD_I2C.
1299 If you use the software i2c interface (CONFIG_SOFT_I2C)
1300 then the following macros need to be defined (examples are
1301 from include/configs/lwmon.h):
1305 (Optional). Any commands necessary to enable the I2C
1306 controller or configure ports.
1308 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1312 (Only for MPC8260 CPU). The I/O port to use (the code
1313 assumes both bits are on the same port). Valid values
1314 are 0..3 for ports A..D.
1318 The code necessary to make the I2C data line active
1319 (driven). If the data line is open collector, this
1322 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1326 The code necessary to make the I2C data line tri-stated
1327 (inactive). If the data line is open collector, this
1330 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1334 Code that returns TRUE if the I2C data line is high,
1337 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1341 If <bit> is TRUE, sets the I2C data line high. If it
1342 is FALSE, it clears it (low).
1344 eg: #define I2C_SDA(bit) \
1345 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1346 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1350 If <bit> is TRUE, sets the I2C clock line high. If it
1351 is FALSE, it clears it (low).
1353 eg: #define I2C_SCL(bit) \
1354 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1355 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1359 This delay is invoked four times per clock cycle so this
1360 controls the rate of data transfer. The data rate thus
1361 is 1 / (I2C_DELAY * 4). Often defined to be something
1364 #define I2C_DELAY udelay(2)
1366 CONFIG_SYS_I2C_INIT_BOARD
1368 When a board is reset during an i2c bus transfer
1369 chips might think that the current transfer is still
1370 in progress. On some boards it is possible to access
1371 the i2c SCLK line directly, either by using the
1372 processor pin as a GPIO or by having a second pin
1373 connected to the bus. If this option is defined a
1374 custom i2c_init_board() routine in boards/xxx/board.c
1375 is run early in the boot sequence.
1377 CONFIG_I2CFAST (PPC405GP|PPC405EP only)
1379 This option enables configuration of bi_iic_fast[] flags
1380 in u-boot bd_info structure based on u-boot environment
1381 variable "i2cfast". (see also i2cfast)
1383 CONFIG_I2C_MULTI_BUS
1385 This option allows the use of multiple I2C buses, each of which
1386 must have a controller. At any point in time, only one bus is
1387 active. To switch to a different bus, use the 'i2c dev' command.
1388 Note that bus numbering is zero-based.
1390 CONFIG_SYS_I2C_NOPROBES
1392 This option specifies a list of I2C devices that will be skipped
1393 when the 'i2c probe' command is issued (or 'iprobe' using the legacy
1394 command). If CONFIG_I2C_MULTI_BUS is set, specify a list of bus-device
1395 pairs. Otherwise, specify a 1D array of device addresses
1398 #undef CONFIG_I2C_MULTI_BUS
1399 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1401 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1403 #define CONFIG_I2C_MULTI_BUS
1404 #define CONFIG_SYS_I2C_MULTI_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1406 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1408 CONFIG_SYS_SPD_BUS_NUM
1410 If defined, then this indicates the I2C bus number for DDR SPD.
1411 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1413 CONFIG_SYS_RTC_BUS_NUM
1415 If defined, then this indicates the I2C bus number for the RTC.
1416 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1418 CONFIG_SYS_DTT_BUS_NUM
1420 If defined, then this indicates the I2C bus number for the DTT.
1421 If not defined, then U-Boot assumes that DTT is on I2C bus 0.
1423 CONFIG_SYS_I2C_DTT_ADDR:
1425 If defined, specifies the I2C address of the DTT device.
1426 If not defined, then U-Boot uses predefined value for
1427 specified DTT device.
1431 Define this option if you want to use Freescale's I2C driver in
1432 drivers/i2c/fsl_i2c.c.
1436 Define this option if you have I2C devices reached over 1 .. n
1437 I2C Muxes like the pca9544a. This option addes a new I2C
1438 Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a
1439 new I2C Bus to the existing I2C Busses. If you select the
1440 new Bus with "i2c dev", u-bbot sends first the commandos for
1441 the muxes to activate this new "bus".
1443 CONFIG_I2C_MULTI_BUS must be also defined, to use this
1447 Adding a new I2C Bus reached over 2 pca9544a muxes
1448 The First mux with address 70 and channel 6
1449 The Second mux with address 71 and channel 4
1451 => i2c bus pca9544a:70:6:pca9544a:71:4
1453 Use the "i2c bus" command without parameter, to get a list
1454 of I2C Busses with muxes:
1457 Busses reached over muxes:
1459 reached over Mux(es):
1462 reached over Mux(es):
1467 If you now switch to the new I2C Bus 3 with "i2c dev 3"
1468 u-boot sends First the Commando to the mux@70 to enable
1469 channel 6, and then the Commando to the mux@71 to enable
1472 After that, you can use the "normal" i2c commands as
1473 usual, to communicate with your I2C devices behind
1476 This option is actually implemented for the bitbanging
1477 algorithm in common/soft_i2c.c and for the Hardware I2C
1478 Bus on the MPC8260. But it should be not so difficult
1479 to add this option to other architectures.
1482 - SPI Support: CONFIG_SPI
1484 Enables SPI driver (so far only tested with
1485 SPI EEPROM, also an instance works with Crystal A/D and
1486 D/As on the SACSng board)
1490 Enables extended (16-bit) SPI EEPROM addressing.
1491 (symmetrical to CONFIG_I2C_X)
1495 Enables a software (bit-bang) SPI driver rather than
1496 using hardware support. This is a general purpose
1497 driver that only requires three general I/O port pins
1498 (two outputs, one input) to function. If this is
1499 defined, the board configuration must define several
1500 SPI configuration items (port pins to use, etc). For
1501 an example, see include/configs/sacsng.h.
1505 Enables a hardware SPI driver for general-purpose reads
1506 and writes. As with CONFIG_SOFT_SPI, the board configuration
1507 must define a list of chip-select function pointers.
1508 Currently supported on some MPC8xxx processors. For an
1509 example, see include/configs/mpc8349emds.h.
1513 Enables the driver for the SPI controllers on i.MX and MXC
1514 SoCs. Currently only i.MX31 is supported.
1516 - FPGA Support: CONFIG_FPGA
1518 Enables FPGA subsystem.
1520 CONFIG_FPGA_<vendor>
1522 Enables support for specific chip vendors.
1525 CONFIG_FPGA_<family>
1527 Enables support for FPGA family.
1528 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1532 Specify the number of FPGA devices to support.
1534 CONFIG_SYS_FPGA_PROG_FEEDBACK
1536 Enable printing of hash marks during FPGA configuration.
1538 CONFIG_SYS_FPGA_CHECK_BUSY
1540 Enable checks on FPGA configuration interface busy
1541 status by the configuration function. This option
1542 will require a board or device specific function to
1547 If defined, a function that provides delays in the FPGA
1548 configuration driver.
1550 CONFIG_SYS_FPGA_CHECK_CTRLC
1551 Allow Control-C to interrupt FPGA configuration
1553 CONFIG_SYS_FPGA_CHECK_ERROR
1555 Check for configuration errors during FPGA bitfile
1556 loading. For example, abort during Virtex II
1557 configuration if the INIT_B line goes low (which
1558 indicated a CRC error).
1560 CONFIG_SYS_FPGA_WAIT_INIT
1562 Maximum time to wait for the INIT_B line to deassert
1563 after PROB_B has been deasserted during a Virtex II
1564 FPGA configuration sequence. The default time is 500
1567 CONFIG_SYS_FPGA_WAIT_BUSY
1569 Maximum time to wait for BUSY to deassert during
1570 Virtex II FPGA configuration. The default is 5 ms.
1572 CONFIG_SYS_FPGA_WAIT_CONFIG
1574 Time to wait after FPGA configuration. The default is
1577 - Configuration Management:
1580 If defined, this string will be added to the U-Boot
1581 version information (U_BOOT_VERSION)
1583 - Vendor Parameter Protection:
1585 U-Boot considers the values of the environment
1586 variables "serial#" (Board Serial Number) and
1587 "ethaddr" (Ethernet Address) to be parameters that
1588 are set once by the board vendor / manufacturer, and
1589 protects these variables from casual modification by
1590 the user. Once set, these variables are read-only,
1591 and write or delete attempts are rejected. You can
1592 change this behaviour:
1594 If CONFIG_ENV_OVERWRITE is #defined in your config
1595 file, the write protection for vendor parameters is
1596 completely disabled. Anybody can change or delete
1599 Alternatively, if you #define _both_ CONFIG_ETHADDR
1600 _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1601 Ethernet address is installed in the environment,
1602 which can be changed exactly ONCE by the user. [The
1603 serial# is unaffected by this, i. e. it remains
1609 Define this variable to enable the reservation of
1610 "protected RAM", i. e. RAM which is not overwritten
1611 by U-Boot. Define CONFIG_PRAM to hold the number of
1612 kB you want to reserve for pRAM. You can overwrite
1613 this default value by defining an environment
1614 variable "pram" to the number of kB you want to
1615 reserve. Note that the board info structure will
1616 still show the full amount of RAM. If pRAM is
1617 reserved, a new environment variable "mem" will
1618 automatically be defined to hold the amount of
1619 remaining RAM in a form that can be passed as boot
1620 argument to Linux, for instance like that:
1622 setenv bootargs ... mem=\${mem}
1625 This way you can tell Linux not to use this memory,
1626 either, which results in a memory region that will
1627 not be affected by reboots.
1629 *WARNING* If your board configuration uses automatic
1630 detection of the RAM size, you must make sure that
1631 this memory test is non-destructive. So far, the
1632 following board configurations are known to be
1635 ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,
1636 HERMES, IP860, RPXlite, LWMON, LANTEC,
1637 PCU_E, FLAGADM, TQM8260
1642 Define this variable to stop the system in case of a
1643 fatal error, so that you have to reset it manually.
1644 This is probably NOT a good idea for an embedded
1645 system where you want the system to reboot
1646 automatically as fast as possible, but it may be
1647 useful during development since you can try to debug
1648 the conditions that lead to the situation.
1650 CONFIG_NET_RETRY_COUNT
1652 This variable defines the number of retries for
1653 network operations like ARP, RARP, TFTP, or BOOTP
1654 before giving up the operation. If not defined, a
1655 default value of 5 is used.
1659 Timeout waiting for an ARP reply in milliseconds.
1661 - Command Interpreter:
1662 CONFIG_AUTO_COMPLETE
1664 Enable auto completion of commands using TAB.
1666 Note that this feature has NOT been implemented yet
1667 for the "hush" shell.
1670 CONFIG_SYS_HUSH_PARSER
1672 Define this variable to enable the "hush" shell (from
1673 Busybox) as command line interpreter, thus enabling
1674 powerful command line syntax like
1675 if...then...else...fi conditionals or `&&' and '||'
1676 constructs ("shell scripts").
1678 If undefined, you get the old, much simpler behaviour
1679 with a somewhat smaller memory footprint.
1682 CONFIG_SYS_PROMPT_HUSH_PS2
1684 This defines the secondary prompt string, which is
1685 printed when the command interpreter needs more input
1686 to complete a command. Usually "> ".
1690 In the current implementation, the local variables
1691 space and global environment variables space are
1692 separated. Local variables are those you define by
1693 simply typing `name=value'. To access a local
1694 variable later on, you have write `$name' or
1695 `${name}'; to execute the contents of a variable
1696 directly type `$name' at the command prompt.
1698 Global environment variables are those you use
1699 setenv/printenv to work with. To run a command stored
1700 in such a variable, you need to use the run command,
1701 and you must not use the '$' sign to access them.
1703 To store commands and special characters in a
1704 variable, please use double quotation marks
1705 surrounding the whole text of the variable, instead
1706 of the backslashes before semicolons and special
1709 - Commandline Editing and History:
1710 CONFIG_CMDLINE_EDITING
1712 Enable editing and History functions for interactive
1713 commandline input operations
1715 - Default Environment:
1716 CONFIG_EXTRA_ENV_SETTINGS
1718 Define this to contain any number of null terminated
1719 strings (variable = value pairs) that will be part of
1720 the default environment compiled into the boot image.
1722 For example, place something like this in your
1723 board's config file:
1725 #define CONFIG_EXTRA_ENV_SETTINGS \
1729 Warning: This method is based on knowledge about the
1730 internal format how the environment is stored by the
1731 U-Boot code. This is NOT an official, exported
1732 interface! Although it is unlikely that this format
1733 will change soon, there is no guarantee either.
1734 You better know what you are doing here.
1736 Note: overly (ab)use of the default environment is
1737 discouraged. Make sure to check other ways to preset
1738 the environment like the autoscript function or the
1741 - DataFlash Support:
1742 CONFIG_HAS_DATAFLASH
1744 Defining this option enables DataFlash features and
1745 allows to read/write in Dataflash via the standard
1748 - SystemACE Support:
1751 Adding this option adds support for Xilinx SystemACE
1752 chips attached via some sort of local bus. The address
1753 of the chip must also be defined in the
1754 CONFIG_SYS_SYSTEMACE_BASE macro. For example:
1756 #define CONFIG_SYSTEMACE
1757 #define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000
1759 When SystemACE support is added, the "ace" device type
1760 becomes available to the fat commands, i.e. fatls.
1762 - TFTP Fixed UDP Port:
1765 If this is defined, the environment variable tftpsrcp
1766 is used to supply the TFTP UDP source port value.
1767 If tftpsrcp isn't defined, the normal pseudo-random port
1768 number generator is used.
1770 Also, the environment variable tftpdstp is used to supply
1771 the TFTP UDP destination port value. If tftpdstp isn't
1772 defined, the normal port 69 is used.
1774 The purpose for tftpsrcp is to allow a TFTP server to
1775 blindly start the TFTP transfer using the pre-configured
1776 target IP address and UDP port. This has the effect of
1777 "punching through" the (Windows XP) firewall, allowing
1778 the remainder of the TFTP transfer to proceed normally.
1779 A better solution is to properly configure the firewall,
1780 but sometimes that is not allowed.
1782 - Show boot progress:
1783 CONFIG_SHOW_BOOT_PROGRESS
1785 Defining this option allows to add some board-
1786 specific code (calling a user-provided function
1787 "show_boot_progress(int)") that enables you to show
1788 the system's boot progress on some display (for
1789 example, some LED's) on your board. At the moment,
1790 the following checkpoints are implemented:
1792 - Automatic software updates via TFTP server
1794 CONFIG_UPDATE_TFTP_CNT_MAX
1795 CONFIG_UPDATE_TFTP_MSEC_MAX
1797 These options enable and control the auto-update feature;
1798 for a more detailed description refer to doc/README.update.
1800 Legacy uImage format:
1803 1 common/cmd_bootm.c before attempting to boot an image
1804 -1 common/cmd_bootm.c Image header has bad magic number
1805 2 common/cmd_bootm.c Image header has correct magic number
1806 -2 common/cmd_bootm.c Image header has bad checksum
1807 3 common/cmd_bootm.c Image header has correct checksum
1808 -3 common/cmd_bootm.c Image data has bad checksum
1809 4 common/cmd_bootm.c Image data has correct checksum
1810 -4 common/cmd_bootm.c Image is for unsupported architecture
1811 5 common/cmd_bootm.c Architecture check OK
1812 -5 common/cmd_bootm.c Wrong Image Type (not kernel, multi)
1813 6 common/cmd_bootm.c Image Type check OK
1814 -6 common/cmd_bootm.c gunzip uncompression error
1815 -7 common/cmd_bootm.c Unimplemented compression type
1816 7 common/cmd_bootm.c Uncompression OK
1817 8 common/cmd_bootm.c No uncompress/copy overwrite error
1818 -9 common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)
1820 9 common/image.c Start initial ramdisk verification
1821 -10 common/image.c Ramdisk header has bad magic number
1822 -11 common/image.c Ramdisk header has bad checksum
1823 10 common/image.c Ramdisk header is OK
1824 -12 common/image.c Ramdisk data has bad checksum
1825 11 common/image.c Ramdisk data has correct checksum
1826 12 common/image.c Ramdisk verification complete, start loading
1827 -13 common/image.c Wrong Image Type (not PPC Linux ramdisk)
1828 13 common/image.c Start multifile image verification
1829 14 common/image.c No initial ramdisk, no multifile, continue.
1831 15 lib_<arch>/bootm.c All preparation done, transferring control to OS
1833 -30 lib_ppc/board.c Fatal error, hang the system
1834 -31 post/post.c POST test failed, detected by post_output_backlog()
1835 -32 post/post.c POST test failed, detected by post_run_single()
1837 34 common/cmd_doc.c before loading a Image from a DOC device
1838 -35 common/cmd_doc.c Bad usage of "doc" command
1839 35 common/cmd_doc.c correct usage of "doc" command
1840 -36 common/cmd_doc.c No boot device
1841 36 common/cmd_doc.c correct boot device
1842 -37 common/cmd_doc.c Unknown Chip ID on boot device
1843 37 common/cmd_doc.c correct chip ID found, device available
1844 -38 common/cmd_doc.c Read Error on boot device
1845 38 common/cmd_doc.c reading Image header from DOC device OK
1846 -39 common/cmd_doc.c Image header has bad magic number
1847 39 common/cmd_doc.c Image header has correct magic number
1848 -40 common/cmd_doc.c Error reading Image from DOC device
1849 40 common/cmd_doc.c Image header has correct magic number
1850 41 common/cmd_ide.c before loading a Image from a IDE device
1851 -42 common/cmd_ide.c Bad usage of "ide" command
1852 42 common/cmd_ide.c correct usage of "ide" command
1853 -43 common/cmd_ide.c No boot device
1854 43 common/cmd_ide.c boot device found
1855 -44 common/cmd_ide.c Device not available
1856 44 common/cmd_ide.c Device available
1857 -45 common/cmd_ide.c wrong partition selected
1858 45 common/cmd_ide.c partition selected
1859 -46 common/cmd_ide.c Unknown partition table
1860 46 common/cmd_ide.c valid partition table found
1861 -47 common/cmd_ide.c Invalid partition type
1862 47 common/cmd_ide.c correct partition type
1863 -48 common/cmd_ide.c Error reading Image Header on boot device
1864 48 common/cmd_ide.c reading Image Header from IDE device OK
1865 -49 common/cmd_ide.c Image header has bad magic number
1866 49 common/cmd_ide.c Image header has correct magic number
1867 -50 common/cmd_ide.c Image header has bad checksum
1868 50 common/cmd_ide.c Image header has correct checksum
1869 -51 common/cmd_ide.c Error reading Image from IDE device
1870 51 common/cmd_ide.c reading Image from IDE device OK
1871 52 common/cmd_nand.c before loading a Image from a NAND device
1872 -53 common/cmd_nand.c Bad usage of "nand" command
1873 53 common/cmd_nand.c correct usage of "nand" command
1874 -54 common/cmd_nand.c No boot device
1875 54 common/cmd_nand.c boot device found
1876 -55 common/cmd_nand.c Unknown Chip ID on boot device
1877 55 common/cmd_nand.c correct chip ID found, device available
1878 -56 common/cmd_nand.c Error reading Image Header on boot device
1879 56 common/cmd_nand.c reading Image Header from NAND device OK
1880 -57 common/cmd_nand.c Image header has bad magic number
1881 57 common/cmd_nand.c Image header has correct magic number
1882 -58 common/cmd_nand.c Error reading Image from NAND device
1883 58 common/cmd_nand.c reading Image from NAND device OK
1885 -60 common/env_common.c Environment has a bad CRC, using default
1887 64 net/eth.c starting with Ethernet configuration.
1888 -64 net/eth.c no Ethernet found.
1889 65 net/eth.c Ethernet found.
1891 -80 common/cmd_net.c usage wrong
1892 80 common/cmd_net.c before calling NetLoop()
1893 -81 common/cmd_net.c some error in NetLoop() occurred
1894 81 common/cmd_net.c NetLoop() back without error
1895 -82 common/cmd_net.c size == 0 (File with size 0 loaded)
1896 82 common/cmd_net.c trying automatic boot
1897 83 common/cmd_net.c running autoscript
1898 -83 common/cmd_net.c some error in automatic boot or autoscript
1899 84 common/cmd_net.c end without errors
1904 100 common/cmd_bootm.c Kernel FIT Image has correct format
1905 -100 common/cmd_bootm.c Kernel FIT Image has incorrect format
1906 101 common/cmd_bootm.c No Kernel subimage unit name, using configuration
1907 -101 common/cmd_bootm.c Can't get configuration for kernel subimage
1908 102 common/cmd_bootm.c Kernel unit name specified
1909 -103 common/cmd_bootm.c Can't get kernel subimage node offset
1910 103 common/cmd_bootm.c Found configuration node
1911 104 common/cmd_bootm.c Got kernel subimage node offset
1912 -104 common/cmd_bootm.c Kernel subimage hash verification failed
1913 105 common/cmd_bootm.c Kernel subimage hash verification OK
1914 -105 common/cmd_bootm.c Kernel subimage is for unsupported architecture
1915 106 common/cmd_bootm.c Architecture check OK
1916 -106 common/cmd_bootm.c Kernel subimage has wrong type
1917 107 common/cmd_bootm.c Kernel subimage type OK
1918 -107 common/cmd_bootm.c Can't get kernel subimage data/size
1919 108 common/cmd_bootm.c Got kernel subimage data/size
1920 -108 common/cmd_bootm.c Wrong image type (not legacy, FIT)
1921 -109 common/cmd_bootm.c Can't get kernel subimage type
1922 -110 common/cmd_bootm.c Can't get kernel subimage comp
1923 -111 common/cmd_bootm.c Can't get kernel subimage os
1924 -112 common/cmd_bootm.c Can't get kernel subimage load address
1925 -113 common/cmd_bootm.c Image uncompress/copy overwrite error
1927 120 common/image.c Start initial ramdisk verification
1928 -120 common/image.c Ramdisk FIT image has incorrect format
1929 121 common/image.c Ramdisk FIT image has correct format
1930 122 common/image.c No ramdisk subimage unit name, using configuration
1931 -122 common/image.c Can't get configuration for ramdisk subimage
1932 123 common/image.c Ramdisk unit name specified
1933 -124 common/image.c Can't get ramdisk subimage node offset
1934 125 common/image.c Got ramdisk subimage node offset
1935 -125 common/image.c Ramdisk subimage hash verification failed
1936 126 common/image.c Ramdisk subimage hash verification OK
1937 -126 common/image.c Ramdisk subimage for unsupported architecture
1938 127 common/image.c Architecture check OK
1939 -127 common/image.c Can't get ramdisk subimage data/size
1940 128 common/image.c Got ramdisk subimage data/size
1941 129 common/image.c Can't get ramdisk load address
1942 -129 common/image.c Got ramdisk load address
1944 -130 common/cmd_doc.c Incorrect FIT image format
1945 131 common/cmd_doc.c FIT image format OK
1947 -140 common/cmd_ide.c Incorrect FIT image format
1948 141 common/cmd_ide.c FIT image format OK
1950 -150 common/cmd_nand.c Incorrect FIT image format
1951 151 common/cmd_nand.c FIT image format OK
1957 [so far only for SMDK2400 and TRAB boards]
1959 - Modem support enable:
1960 CONFIG_MODEM_SUPPORT
1962 - RTS/CTS Flow control enable:
1965 - Modem debug support:
1966 CONFIG_MODEM_SUPPORT_DEBUG
1968 Enables debugging stuff (char screen[1024], dbg())
1969 for modem support. Useful only with BDI2000.
1971 - Interrupt support (PPC):
1973 There are common interrupt_init() and timer_interrupt()
1974 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1975 for CPU specific initialization. interrupt_init_cpu()
1976 should set decrementer_count to appropriate value. If
1977 CPU resets decrementer automatically after interrupt
1978 (ppc4xx) it should set decrementer_count to zero.
1979 timer_interrupt() calls timer_interrupt_cpu() for CPU
1980 specific handling. If board has watchdog / status_led
1981 / other_activity_monitor it works automatically from
1982 general timer_interrupt().
1986 In the target system modem support is enabled when a
1987 specific key (key combination) is pressed during
1988 power-on. Otherwise U-Boot will boot normally
1989 (autoboot). The key_pressed() function is called from
1990 board_init(). Currently key_pressed() is a dummy
1991 function, returning 1 and thus enabling modem
1994 If there are no modem init strings in the
1995 environment, U-Boot proceed to autoboot; the
1996 previous output (banner, info printfs) will be
1999 See also: doc/README.Modem
2002 Configuration Settings:
2003 -----------------------
2005 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
2006 undefine this when you're short of memory.
2008 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
2009 prompt for user input.
2011 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
2013 - CONFIG_SYS_PBSIZE: Buffer size for Console output
2015 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
2017 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
2018 the application (usually a Linux kernel) when it is
2021 - CONFIG_SYS_BAUDRATE_TABLE:
2022 List of legal baudrate settings for this board.
2024 - CONFIG_SYS_CONSOLE_INFO_QUIET
2025 Suppress display of console information at boot.
2027 - CONFIG_SYS_CONSOLE_IS_IN_ENV
2028 If the board specific function
2029 extern int overwrite_console (void);
2030 returns 1, the stdin, stderr and stdout are switched to the
2031 serial port, else the settings in the environment are used.
2033 - CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE
2034 Enable the call to overwrite_console().
2036 - CONFIG_SYS_CONSOLE_ENV_OVERWRITE
2037 Enable overwrite of previous console environment settings.
2039 - CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
2040 Begin and End addresses of the area used by the
2043 - CONFIG_SYS_ALT_MEMTEST:
2044 Enable an alternate, more extensive memory test.
2046 - CONFIG_SYS_MEMTEST_SCRATCH:
2047 Scratch address used by the alternate memory test
2048 You only need to set this if address zero isn't writeable
2050 - CONFIG_SYS_MEM_TOP_HIDE (PPC only):
2051 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
2052 this specified memory area will get subtracted from the top
2053 (end) of RAM and won't get "touched" at all by U-Boot. By
2054 fixing up gd->ram_size the Linux kernel should gets passed
2055 the now "corrected" memory size and won't touch it either.
2056 This should work for arch/ppc and arch/powerpc. Only Linux
2057 board ports in arch/powerpc with bootwrapper support that
2058 recalculate the memory size from the SDRAM controller setup
2059 will have to get fixed in Linux additionally.
2061 This option can be used as a workaround for the 440EPx/GRx
2062 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
2065 WARNING: Please make sure that this value is a multiple of
2066 the Linux page size (normally 4k). If this is not the case,
2067 then the end address of the Linux memory will be located at a
2068 non page size aligned address and this could cause major
2071 - CONFIG_SYS_TFTP_LOADADDR:
2072 Default load address for network file downloads
2074 - CONFIG_SYS_LOADS_BAUD_CHANGE:
2075 Enable temporary baudrate change while serial download
2077 - CONFIG_SYS_SDRAM_BASE:
2078 Physical start address of SDRAM. _Must_ be 0 here.
2080 - CONFIG_SYS_MBIO_BASE:
2081 Physical start address of Motherboard I/O (if using a
2084 - CONFIG_SYS_FLASH_BASE:
2085 Physical start address of Flash memory.
2087 - CONFIG_SYS_MONITOR_BASE:
2088 Physical start address of boot monitor code (set by
2089 make config files to be same as the text base address
2090 (TEXT_BASE) used when linking) - same as
2091 CONFIG_SYS_FLASH_BASE when booting from flash.
2093 - CONFIG_SYS_MONITOR_LEN:
2094 Size of memory reserved for monitor code, used to
2095 determine _at_compile_time_ (!) if the environment is
2096 embedded within the U-Boot image, or in a separate
2099 - CONFIG_SYS_MALLOC_LEN:
2100 Size of DRAM reserved for malloc() use.
2102 - CONFIG_SYS_BOOTM_LEN:
2103 Normally compressed uImages are limited to an
2104 uncompressed size of 8 MBytes. If this is not enough,
2105 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2106 to adjust this setting to your needs.
2108 - CONFIG_SYS_BOOTMAPSZ:
2109 Maximum size of memory mapped by the startup code of
2110 the Linux kernel; all data that must be processed by
2111 the Linux kernel (bd_info, boot arguments, FDT blob if
2112 used) must be put below this limit, unless "bootm_low"
2113 enviroment variable is defined and non-zero. In such case
2114 all data for the Linux kernel must be between "bootm_low"
2115 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.
2117 - CONFIG_SYS_MAX_FLASH_BANKS:
2118 Max number of Flash memory banks
2120 - CONFIG_SYS_MAX_FLASH_SECT:
2121 Max number of sectors on a Flash chip
2123 - CONFIG_SYS_FLASH_ERASE_TOUT:
2124 Timeout for Flash erase operations (in ms)
2126 - CONFIG_SYS_FLASH_WRITE_TOUT:
2127 Timeout for Flash write operations (in ms)
2129 - CONFIG_SYS_FLASH_LOCK_TOUT
2130 Timeout for Flash set sector lock bit operation (in ms)
2132 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2133 Timeout for Flash clear lock bits operation (in ms)
2135 - CONFIG_SYS_FLASH_PROTECTION
2136 If defined, hardware flash sectors protection is used
2137 instead of U-Boot software protection.
2139 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2141 Enable TFTP transfers directly to flash memory;
2142 without this option such a download has to be
2143 performed in two steps: (1) download to RAM, and (2)
2144 copy from RAM to flash.
2146 The two-step approach is usually more reliable, since
2147 you can check if the download worked before you erase
2148 the flash, but in some situations (when system RAM is
2149 too limited to allow for a temporary copy of the
2150 downloaded image) this option may be very useful.
2152 - CONFIG_SYS_FLASH_CFI:
2153 Define if the flash driver uses extra elements in the
2154 common flash structure for storing flash geometry.
2156 - CONFIG_FLASH_CFI_DRIVER
2157 This option also enables the building of the cfi_flash driver
2158 in the drivers directory
2160 - CONFIG_FLASH_CFI_MTD
2161 This option enables the building of the cfi_mtd driver
2162 in the drivers directory. The driver exports CFI flash
2165 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2166 Use buffered writes to flash.
2168 - CONFIG_FLASH_SPANSION_S29WS_N
2169 s29ws-n MirrorBit flash has non-standard addresses for buffered
2172 - CONFIG_SYS_FLASH_QUIET_TEST
2173 If this option is defined, the common CFI flash doesn't
2174 print it's warning upon not recognized FLASH banks. This
2175 is useful, if some of the configured banks are only
2176 optionally available.
2178 - CONFIG_FLASH_SHOW_PROGRESS
2179 If defined (must be an integer), print out countdown
2180 digits and dots. Recommended value: 45 (9..1) for 80
2181 column displays, 15 (3..1) for 40 column displays.
2183 - CONFIG_SYS_RX_ETH_BUFFER:
2184 Defines the number of Ethernet receive buffers. On some
2185 Ethernet controllers it is recommended to set this value
2186 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2187 buffers can be full shortly after enabling the interface
2188 on high Ethernet traffic.
2189 Defaults to 4 if not defined.
2191 The following definitions that deal with the placement and management
2192 of environment data (variable area); in general, we support the
2193 following configurations:
2195 - CONFIG_ENV_IS_IN_FLASH:
2197 Define this if the environment is in flash memory.
2199 a) The environment occupies one whole flash sector, which is
2200 "embedded" in the text segment with the U-Boot code. This
2201 happens usually with "bottom boot sector" or "top boot
2202 sector" type flash chips, which have several smaller
2203 sectors at the start or the end. For instance, such a
2204 layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
2205 such a case you would place the environment in one of the
2206 4 kB sectors - with U-Boot code before and after it. With
2207 "top boot sector" type flash chips, you would put the
2208 environment in one of the last sectors, leaving a gap
2209 between U-Boot and the environment.
2211 - CONFIG_ENV_OFFSET:
2213 Offset of environment data (variable area) to the
2214 beginning of flash memory; for instance, with bottom boot
2215 type flash chips the second sector can be used: the offset
2216 for this sector is given here.
2218 CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.
2222 This is just another way to specify the start address of
2223 the flash sector containing the environment (instead of
2226 - CONFIG_ENV_SECT_SIZE:
2228 Size of the sector containing the environment.
2231 b) Sometimes flash chips have few, equal sized, BIG sectors.
2232 In such a case you don't want to spend a whole sector for
2237 If you use this in combination with CONFIG_ENV_IS_IN_FLASH
2238 and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
2239 of this flash sector for the environment. This saves
2240 memory for the RAM copy of the environment.
2242 It may also save flash memory if you decide to use this
2243 when your environment is "embedded" within U-Boot code,
2244 since then the remainder of the flash sector could be used
2245 for U-Boot code. It should be pointed out that this is
2246 STRONGLY DISCOURAGED from a robustness point of view:
2247 updating the environment in flash makes it always
2248 necessary to erase the WHOLE sector. If something goes
2249 wrong before the contents has been restored from a copy in
2250 RAM, your target system will be dead.
2252 - CONFIG_ENV_ADDR_REDUND
2253 CONFIG_ENV_SIZE_REDUND
2255 These settings describe a second storage area used to hold
2256 a redundant copy of the environment data, so that there is
2257 a valid backup copy in case there is a power failure during
2258 a "saveenv" operation.
2260 BE CAREFUL! Any changes to the flash layout, and some changes to the
2261 source code will make it necessary to adapt <board>/u-boot.lds*
2265 - CONFIG_ENV_IS_IN_NVRAM:
2267 Define this if you have some non-volatile memory device
2268 (NVRAM, battery buffered SRAM) which you want to use for the
2274 These two #defines are used to determine the memory area you
2275 want to use for environment. It is assumed that this memory
2276 can just be read and written to, without any special
2279 BE CAREFUL! The first access to the environment happens quite early
2280 in U-Boot initalization (when we try to get the setting of for the
2281 console baudrate). You *MUST* have mapped your NVRAM area then, or
2284 Please note that even with NVRAM we still use a copy of the
2285 environment in RAM: we could work on NVRAM directly, but we want to
2286 keep settings there always unmodified except somebody uses "saveenv"
2287 to save the current settings.
2290 - CONFIG_ENV_IS_IN_EEPROM:
2292 Use this if you have an EEPROM or similar serial access
2293 device and a driver for it.
2295 - CONFIG_ENV_OFFSET:
2298 These two #defines specify the offset and size of the
2299 environment area within the total memory of your EEPROM.
2301 - CONFIG_SYS_I2C_EEPROM_ADDR:
2302 If defined, specified the chip address of the EEPROM device.
2303 The default address is zero.
2305 - CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
2306 If defined, the number of bits used to address bytes in a
2307 single page in the EEPROM device. A 64 byte page, for example
2308 would require six bits.
2310 - CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
2311 If defined, the number of milliseconds to delay between
2312 page writes. The default is zero milliseconds.
2314 - CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
2315 The length in bytes of the EEPROM memory array address. Note
2316 that this is NOT the chip address length!
2318 - CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
2319 EEPROM chips that implement "address overflow" are ones
2320 like Catalyst 24WC04/08/16 which has 9/10/11 bits of
2321 address and the extra bits end up in the "chip address" bit
2322 slots. This makes a 24WC08 (1Kbyte) chip look like four 256
2325 Note that we consider the length of the address field to
2326 still be one byte because the extra address bits are hidden
2327 in the chip address.
2329 - CONFIG_SYS_EEPROM_SIZE:
2330 The size in bytes of the EEPROM device.
2333 - CONFIG_ENV_IS_IN_DATAFLASH:
2335 Define this if you have a DataFlash memory device which you
2336 want to use for the environment.
2338 - CONFIG_ENV_OFFSET:
2342 These three #defines specify the offset and size of the
2343 environment area within the total memory of your DataFlash placed
2344 at the specified address.
2346 - CONFIG_ENV_IS_IN_NAND:
2348 Define this if you have a NAND device which you want to use
2349 for the environment.
2351 - CONFIG_ENV_OFFSET:
2354 These two #defines specify the offset and size of the environment
2355 area within the first NAND device.
2357 - CONFIG_ENV_OFFSET_REDUND
2359 This setting describes a second storage area of CONFIG_ENV_SIZE
2360 size used to hold a redundant copy of the environment data,
2361 so that there is a valid backup copy in case there is a
2362 power failure during a "saveenv" operation.
2364 Note: CONFIG_ENV_OFFSET and CONFIG_ENV_OFFSET_REDUND must be aligned
2365 to a block boundary, and CONFIG_ENV_SIZE must be a multiple of
2366 the NAND devices block size.
2368 - CONFIG_SYS_SPI_INIT_OFFSET
2370 Defines offset to the initial SPI buffer area in DPRAM. The
2371 area is used at an early stage (ROM part) if the environment
2372 is configured to reside in the SPI EEPROM: We need a 520 byte
2373 scratch DPRAM area. It is used between the two initialization
2374 calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
2375 to be a good choice since it makes it far enough from the
2376 start of the data area as well as from the stack pointer.
2378 Please note that the environment is read-only until the monitor
2379 has been relocated to RAM and a RAM copy of the environment has been
2380 created; also, when using EEPROM you will have to use getenv_r()
2381 until then to read environment variables.
2383 The environment is protected by a CRC32 checksum. Before the monitor
2384 is relocated into RAM, as a result of a bad CRC you will be working
2385 with the compiled-in default environment - *silently*!!! [This is
2386 necessary, because the first environment variable we need is the
2387 "baudrate" setting for the console - if we have a bad CRC, we don't
2388 have any device yet where we could complain.]
2390 Note: once the monitor has been relocated, then it will complain if
2391 the default environment is used; a new CRC is computed as soon as you
2392 use the "saveenv" command to store a valid environment.
2394 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2395 Echo the inverted Ethernet link state to the fault LED.
2397 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2398 also needs to be defined.
2400 - CONFIG_SYS_FAULT_MII_ADDR:
2401 MII address of the PHY to check for the Ethernet link state.
2403 - CONFIG_SYS_64BIT_VSPRINTF:
2404 Makes vsprintf (and all *printf functions) support printing
2405 of 64bit values by using the L quantifier
2407 - CONFIG_SYS_64BIT_STRTOUL:
2408 Adds simple_strtoull that returns a 64bit value
2410 Low Level (hardware related) configuration options:
2411 ---------------------------------------------------
2413 - CONFIG_SYS_CACHELINE_SIZE:
2414 Cache Line Size of the CPU.
2416 - CONFIG_SYS_DEFAULT_IMMR:
2417 Default address of the IMMR after system reset.
2419 Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
2420 and RPXsuper) to be able to adjust the position of
2421 the IMMR register after a reset.
2423 - Floppy Disk Support:
2424 CONFIG_SYS_FDC_DRIVE_NUMBER
2426 the default drive number (default value 0)
2428 CONFIG_SYS_ISA_IO_STRIDE
2430 defines the spacing between FDC chipset registers
2433 CONFIG_SYS_ISA_IO_OFFSET
2435 defines the offset of register from address. It
2436 depends on which part of the data bus is connected to
2437 the FDC chipset. (default value 0)
2439 If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and
2440 CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their
2443 if CONFIG_SYS_FDC_HW_INIT is defined, then the function
2444 fdc_hw_init() is called at the beginning of the FDC
2445 setup. fdc_hw_init() must be provided by the board
2446 source code. It is used to make hardware dependant
2449 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2450 DO NOT CHANGE unless you know exactly what you're
2451 doing! (11-4) [MPC8xx/82xx systems only]
2453 - CONFIG_SYS_INIT_RAM_ADDR:
2455 Start address of memory area that can be used for
2456 initial data and stack; please note that this must be
2457 writable memory that is working WITHOUT special
2458 initialization, i. e. you CANNOT use normal RAM which
2459 will become available only after programming the
2460 memory controller and running certain initialization
2463 U-Boot uses the following memory types:
2464 - MPC8xx and MPC8260: IMMR (internal memory of the CPU)
2465 - MPC824X: data cache
2466 - PPC4xx: data cache
2468 - CONFIG_SYS_GBL_DATA_OFFSET:
2470 Offset of the initial data structure in the memory
2471 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2472 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2473 data is located at the end of the available space
2474 (sometimes written as (CONFIG_SYS_INIT_RAM_END -
2475 CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just
2476 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2477 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2480 On the MPC824X (or other systems that use the data
2481 cache for initial memory) the address chosen for
2482 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2483 point to an otherwise UNUSED address space between
2484 the top of RAM and the start of the PCI space.
2486 - CONFIG_SYS_SIUMCR: SIU Module Configuration (11-6)
2488 - CONFIG_SYS_SYPCR: System Protection Control (11-9)
2490 - CONFIG_SYS_TBSCR: Time Base Status and Control (11-26)
2492 - CONFIG_SYS_PISCR: Periodic Interrupt Status and Control (11-31)
2494 - CONFIG_SYS_PLPRCR: PLL, Low-Power, and Reset Control Register (15-30)
2496 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2498 - CONFIG_SYS_OR_TIMING_SDRAM:
2501 - CONFIG_SYS_MAMR_PTA:
2502 periodic timer for refresh
2504 - CONFIG_SYS_DER: Debug Event Register (37-47)
2506 - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
2507 CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
2508 CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
2509 CONFIG_SYS_BR1_PRELIM:
2510 Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
2512 - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
2513 CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
2514 CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
2515 Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
2517 - CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,
2518 CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:
2519 Machine Mode Register and Memory Periodic Timer
2520 Prescaler definitions (SDRAM timing)
2522 - CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:
2523 enable I2C microcode relocation patch (MPC8xx);
2524 define relocation offset in DPRAM [DSP2]
2526 - CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:
2527 enable SMC microcode relocation patch (MPC8xx);
2528 define relocation offset in DPRAM [SMC1]
2530 - CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:
2531 enable SPI microcode relocation patch (MPC8xx);
2532 define relocation offset in DPRAM [SCC4]
2534 - CONFIG_SYS_USE_OSCCLK:
2535 Use OSCM clock mode on MBX8xx board. Be careful,
2536 wrong setting might damage your board. Read
2537 doc/README.MBX before setting this variable!
2539 - CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
2540 Offset of the bootmode word in DPRAM used by post
2541 (Power On Self Tests). This definition overrides
2542 #define'd default value in commproc.h resp.
2545 - CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,
2546 CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,
2547 CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,
2548 CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,
2549 CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
2550 CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,
2551 CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,
2552 CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)
2553 Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.
2556 Get DDR timing information from an I2C EEPROM. Common
2557 with pluggable memory modules such as SODIMMs
2560 I2C address of the SPD EEPROM
2562 - CONFIG_SYS_SPD_BUS_NUM
2563 If SPD EEPROM is on an I2C bus other than the first
2564 one, specify here. Note that the value must resolve
2565 to something your driver can deal with.
2567 - CONFIG_SYS_83XX_DDR_USES_CS0
2568 Only for 83xx systems. If specified, then DDR should
2569 be configured using CS0 and CS1 instead of CS2 and CS3.
2571 - CONFIG_SYS_83XX_DDR_USES_CS0
2572 Only for 83xx systems. If specified, then DDR should
2573 be configured using CS0 and CS1 instead of CS2 and CS3.
2575 - CONFIG_ETHER_ON_FEC[12]
2576 Define to enable FEC[12] on a 8xx series processor.
2578 - CONFIG_FEC[12]_PHY
2579 Define to the hardcoded PHY address which corresponds
2580 to the given FEC; i. e.
2581 #define CONFIG_FEC1_PHY 4
2582 means that the PHY with address 4 is connected to FEC1
2584 When set to -1, means to probe for first available.
2586 - CONFIG_FEC[12]_PHY_NORXERR
2587 The PHY does not have a RXERR line (RMII only).
2588 (so program the FEC to ignore it).
2591 Enable RMII mode for all FECs.
2592 Note that this is a global option, we can't
2593 have one FEC in standard MII mode and another in RMII mode.
2595 - CONFIG_CRC32_VERIFY
2596 Add a verify option to the crc32 command.
2599 => crc32 -v <address> <count> <crc32>
2601 Where address/count indicate a memory area
2602 and crc32 is the correct crc32 which the
2606 Add the "loopw" memory command. This only takes effect if
2607 the memory commands are activated globally (CONFIG_CMD_MEM).
2610 Add the "mdc" and "mwc" memory commands. These are cyclic
2615 This command will print 4 bytes (10,11,12,13) each 500 ms.
2617 => mwc.l 100 12345678 10
2618 This command will write 12345678 to address 100 all 10 ms.
2620 This only takes effect if the memory commands are activated
2621 globally (CONFIG_CMD_MEM).
2623 - CONFIG_SKIP_LOWLEVEL_INIT
2624 - CONFIG_SKIP_RELOCATE_UBOOT
2626 [ARM only] If these variables are defined, then
2627 certain low level initializations (like setting up
2628 the memory controller) are omitted and/or U-Boot does
2629 not relocate itself into RAM.
2630 Normally these variables MUST NOT be defined. The
2631 only exception is when U-Boot is loaded (to RAM) by
2632 some other boot loader or by a debugger which
2633 performs these initializations itself.
2636 Building the Software:
2637 ======================
2639 Building U-Boot has been tested in several native build environments
2640 and in many different cross environments. Of course we cannot support
2641 all possibly existing versions of cross development tools in all
2642 (potentially obsolete) versions. In case of tool chain problems we
2643 recommend to use the ELDK (see http://www.denx.de/wiki/DULG/ELDK)
2644 which is extensively used to build and test U-Boot.
2646 If you are not using a native environment, it is assumed that you
2647 have GNU cross compiling tools available in your path. In this case,
2648 you must set the environment variable CROSS_COMPILE in your shell.
2649 Note that no changes to the Makefile or any other source files are
2650 necessary. For example using the ELDK on a 4xx CPU, please enter:
2652 $ CROSS_COMPILE=ppc_4xx-
2653 $ export CROSS_COMPILE
2655 U-Boot is intended to be simple to build. After installing the
2656 sources you must configure U-Boot for one specific board type. This
2661 where "NAME_config" is the name of one of the existing configu-
2662 rations; see the main Makefile for supported names.
2664 Note: for some board special configuration names may exist; check if
2665 additional information is available from the board vendor; for
2666 instance, the TQM823L systems are available without (standard)
2667 or with LCD support. You can select such additional "features"
2668 when choosing the configuration, i. e.
2671 - will configure for a plain TQM823L, i. e. no LCD support
2673 make TQM823L_LCD_config
2674 - will configure for a TQM823L with U-Boot console on LCD
2679 Finally, type "make all", and you should get some working U-Boot
2680 images ready for download to / installation on your system:
2682 - "u-boot.bin" is a raw binary image
2683 - "u-boot" is an image in ELF binary format
2684 - "u-boot.srec" is in Motorola S-Record format
2686 By default the build is performed locally and the objects are saved
2687 in the source directory. One of the two methods can be used to change
2688 this behavior and build U-Boot to some external directory:
2690 1. Add O= to the make command line invocations:
2692 make O=/tmp/build distclean
2693 make O=/tmp/build NAME_config
2694 make O=/tmp/build all
2696 2. Set environment variable BUILD_DIR to point to the desired location:
2698 export BUILD_DIR=/tmp/build
2703 Note that the command line "O=" setting overrides the BUILD_DIR environment
2707 Please be aware that the Makefiles assume you are using GNU make, so
2708 for instance on NetBSD you might need to use "gmake" instead of
2712 If the system board that you have is not listed, then you will need
2713 to port U-Boot to your hardware platform. To do this, follow these
2716 1. Add a new configuration option for your board to the toplevel
2717 "Makefile" and to the "MAKEALL" script, using the existing
2718 entries as examples. Note that here and at many other places
2719 boards and other names are listed in alphabetical sort order. Please
2721 2. Create a new directory to hold your board specific code. Add any
2722 files you need. In your board directory, you will need at least
2723 the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
2724 3. Create a new configuration file "include/configs/<board>.h" for
2726 3. If you're porting U-Boot to a new CPU, then also create a new
2727 directory to hold your CPU specific code. Add any files you need.
2728 4. Run "make <board>_config" with your new name.
2729 5. Type "make", and you should get a working "u-boot.srec" file
2730 to be installed on your target system.
2731 6. Debug and solve any problems that might arise.
2732 [Of course, this last step is much harder than it sounds.]
2735 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2736 ==============================================================
2738 If you have modified U-Boot sources (for instance added a new board
2739 or support for new devices, a new CPU, etc.) you are expected to
2740 provide feedback to the other developers. The feedback normally takes
2741 the form of a "patch", i. e. a context diff against a certain (latest
2742 official or latest in the git repository) version of U-Boot sources.
2744 But before you submit such a patch, please verify that your modifi-
2745 cation did not break existing code. At least make sure that *ALL* of
2746 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2747 just run the "MAKEALL" script, which will configure and build U-Boot
2748 for ALL supported system. Be warned, this will take a while. You can
2749 select which (cross) compiler to use by passing a `CROSS_COMPILE'
2750 environment variable to the script, i. e. to use the ELDK cross tools
2753 CROSS_COMPILE=ppc_8xx- MAKEALL
2755 or to build on a native PowerPC system you can type
2757 CROSS_COMPILE=' ' MAKEALL
2759 When using the MAKEALL script, the default behaviour is to build
2760 U-Boot in the source directory. This location can be changed by
2761 setting the BUILD_DIR environment variable. Also, for each target
2762 built, the MAKEALL script saves two log files (<target>.ERR and
2763 <target>.MAKEALL) in the <source dir>/LOG directory. This default
2764 location can be changed by setting the MAKEALL_LOGDIR environment
2765 variable. For example:
2767 export BUILD_DIR=/tmp/build
2768 export MAKEALL_LOGDIR=/tmp/log
2769 CROSS_COMPILE=ppc_8xx- MAKEALL
2771 With the above settings build objects are saved in the /tmp/build,
2772 log files are saved in the /tmp/log and the source tree remains clean
2773 during the whole build process.
2776 See also "U-Boot Porting Guide" below.
2779 Monitor Commands - Overview:
2780 ============================
2782 go - start application at address 'addr'
2783 run - run commands in an environment variable
2784 bootm - boot application image from memory
2785 bootp - boot image via network using BootP/TFTP protocol
2786 tftpboot- boot image via network using TFTP protocol
2787 and env variables "ipaddr" and "serverip"
2788 (and eventually "gatewayip")
2789 rarpboot- boot image via network using RARP/TFTP protocol
2790 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2791 loads - load S-Record file over serial line
2792 loadb - load binary file over serial line (kermit mode)
2794 mm - memory modify (auto-incrementing)
2795 nm - memory modify (constant address)
2796 mw - memory write (fill)
2798 cmp - memory compare
2799 crc32 - checksum calculation
2800 imd - i2c memory display
2801 imm - i2c memory modify (auto-incrementing)
2802 inm - i2c memory modify (constant address)
2803 imw - i2c memory write (fill)
2804 icrc32 - i2c checksum calculation
2805 iprobe - probe to discover valid I2C chip addresses
2806 iloop - infinite loop on address range
2807 isdram - print SDRAM configuration information
2808 sspi - SPI utility commands
2809 base - print or set address offset
2810 printenv- print environment variables
2811 setenv - set environment variables
2812 saveenv - save environment variables to persistent storage
2813 protect - enable or disable FLASH write protection
2814 erase - erase FLASH memory
2815 flinfo - print FLASH memory information
2816 bdinfo - print Board Info structure
2817 iminfo - print header information for application image
2818 coninfo - print console devices and informations
2819 ide - IDE sub-system
2820 loop - infinite loop on address range
2821 loopw - infinite write loop on address range
2822 mtest - simple RAM test
2823 icache - enable or disable instruction cache
2824 dcache - enable or disable data cache
2825 reset - Perform RESET of the CPU
2826 echo - echo args to console
2827 version - print monitor version
2828 help - print online help
2829 ? - alias for 'help'
2832 Monitor Commands - Detailed Description:
2833 ========================================
2837 For now: just type "help <command>".
2840 Environment Variables:
2841 ======================
2843 U-Boot supports user configuration using Environment Variables which
2844 can be made persistent by saving to Flash memory.
2846 Environment Variables are set using "setenv", printed using
2847 "printenv", and saved to Flash using "saveenv". Using "setenv"
2848 without a value can be used to delete a variable from the
2849 environment. As long as you don't save the environment you are
2850 working with an in-memory copy. In case the Flash area containing the
2851 environment is erased by accident, a default environment is provided.
2853 Some configuration options can be set using Environment Variables:
2855 baudrate - see CONFIG_BAUDRATE
2857 bootdelay - see CONFIG_BOOTDELAY
2859 bootcmd - see CONFIG_BOOTCOMMAND
2861 bootargs - Boot arguments when booting an RTOS image
2863 bootfile - Name of the image to load with TFTP
2865 bootm_low - Memory range available for image processing in the bootm
2866 command can be restricted. This variable is given as
2867 a hexadecimal number and defines lowest address allowed
2868 for use by the bootm command. See also "bootm_size"
2869 environment variable. Address defined by "bootm_low" is
2870 also the base of the initial memory mapping for the Linux
2871 kernel -- see the description of CONFIG_SYS_BOOTMAPSZ.
2873 bootm_size - Memory range available for image processing in the bootm
2874 command can be restricted. This variable is given as
2875 a hexadecimal number and defines the size of the region
2876 allowed for use by the bootm command. See also "bootm_low"
2877 environment variable.
2879 updatefile - Location of the software update file on a TFTP server, used
2880 by the automatic software update feature. Please refer to
2881 documentation in doc/README.update for more details.
2883 autoload - if set to "no" (any string beginning with 'n'),
2884 "bootp" will just load perform a lookup of the
2885 configuration from the BOOTP server, but not try to
2886 load any image using TFTP
2888 autoscript - if set to "yes" commands like "loadb", "loady",
2889 "bootp", "tftpb", "rarpboot" and "nfs" will attempt
2890 to automatically run script images (by internally
2891 calling "autoscript").
2893 autoscript_uname - if script image is in a format (FIT) this
2894 variable is used to get script subimage unit name.
2896 autostart - if set to "yes", an image loaded using the "bootp",
2897 "rarpboot", "tftpboot" or "diskboot" commands will
2898 be automatically started (by internally calling
2901 If set to "no", a standalone image passed to the
2902 "bootm" command will be copied to the load address
2903 (and eventually uncompressed), but NOT be started.
2904 This can be used to load and uncompress arbitrary
2907 i2cfast - (PPC405GP|PPC405EP only)
2908 if set to 'y' configures Linux I2C driver for fast
2909 mode (400kHZ). This environment variable is used in
2910 initialization code. So, for changes to be effective
2911 it must be saved and board must be reset.
2913 initrd_high - restrict positioning of initrd images:
2914 If this variable is not set, initrd images will be
2915 copied to the highest possible address in RAM; this
2916 is usually what you want since it allows for
2917 maximum initrd size. If for some reason you want to
2918 make sure that the initrd image is loaded below the
2919 CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
2920 variable to a value of "no" or "off" or "0".
2921 Alternatively, you can set it to a maximum upper
2922 address to use (U-Boot will still check that it
2923 does not overwrite the U-Boot stack and data).
2925 For instance, when you have a system with 16 MB
2926 RAM, and want to reserve 4 MB from use by Linux,
2927 you can do this by adding "mem=12M" to the value of
2928 the "bootargs" variable. However, now you must make
2929 sure that the initrd image is placed in the first
2930 12 MB as well - this can be done with
2932 setenv initrd_high 00c00000
2934 If you set initrd_high to 0xFFFFFFFF, this is an
2935 indication to U-Boot that all addresses are legal
2936 for the Linux kernel, including addresses in flash
2937 memory. In this case U-Boot will NOT COPY the
2938 ramdisk at all. This may be useful to reduce the
2939 boot time on your system, but requires that this
2940 feature is supported by your Linux kernel.
2942 ipaddr - IP address; needed for tftpboot command
2944 loadaddr - Default load address for commands like "bootp",
2945 "rarpboot", "tftpboot", "loadb" or "diskboot"
2947 loads_echo - see CONFIG_LOADS_ECHO
2949 serverip - TFTP server IP address; needed for tftpboot command
2951 bootretry - see CONFIG_BOOT_RETRY_TIME
2953 bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
2955 bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
2957 ethprime - When CONFIG_NET_MULTI is enabled controls which
2958 interface is used first.
2960 ethact - When CONFIG_NET_MULTI is enabled controls which
2961 interface is currently active. For example you
2962 can do the following
2964 => setenv ethact FEC ETHERNET
2965 => ping 192.168.0.1 # traffic sent on FEC ETHERNET
2966 => setenv ethact SCC ETHERNET
2967 => ping 10.0.0.1 # traffic sent on SCC ETHERNET
2969 ethrotate - When set to "no" U-Boot does not go through all
2970 available network interfaces.
2971 It just stays at the currently selected interface.
2973 netretry - When set to "no" each network operation will
2974 either succeed or fail without retrying.
2975 When set to "once" the network operation will
2976 fail when all the available network interfaces
2977 are tried once without success.
2978 Useful on scripts which control the retry operation
2981 npe_ucode - see CONFIG_IXP4XX_NPE_EXT_UCOD
2982 if set load address for the NPE microcode
2984 tftpsrcport - If this is set, the value is used for TFTP's
2987 tftpdstport - If this is set, the value is used for TFTP's UDP
2988 destination port instead of the Well Know Port 69.
2990 vlan - When set to a value < 4095 the traffic over
2991 Ethernet is encapsulated/received over 802.1q
2994 The following environment variables may be used and automatically
2995 updated by the network boot commands ("bootp" and "rarpboot"),
2996 depending the information provided by your boot server:
2998 bootfile - see above
2999 dnsip - IP address of your Domain Name Server
3000 dnsip2 - IP address of your secondary Domain Name Server
3001 gatewayip - IP address of the Gateway (Router) to use
3002 hostname - Target hostname
3004 netmask - Subnet Mask
3005 rootpath - Pathname of the root filesystem on the NFS server
3006 serverip - see above
3009 There are two special Environment Variables:
3011 serial# - contains hardware identification information such
3012 as type string and/or serial number
3013 ethaddr - Ethernet address
3015 These variables can be set only once (usually during manufacturing of
3016 the board). U-Boot refuses to delete or overwrite these variables
3017 once they have been set once.
3020 Further special Environment Variables:
3022 ver - Contains the U-Boot version string as printed
3023 with the "version" command. This variable is
3024 readonly (see CONFIG_VERSION_VARIABLE).
3027 Please note that changes to some configuration parameters may take
3028 only effect after the next boot (yes, that's just like Windoze :-).
3031 Command Line Parsing:
3032 =====================
3034 There are two different command line parsers available with U-Boot:
3035 the old "simple" one, and the much more powerful "hush" shell:
3037 Old, simple command line parser:
3038 --------------------------------
3040 - supports environment variables (through setenv / saveenv commands)
3041 - several commands on one line, separated by ';'
3042 - variable substitution using "... ${name} ..." syntax
3043 - special characters ('$', ';') can be escaped by prefixing with '\',
3045 setenv bootcmd bootm \${address}
3046 - You can also escape text by enclosing in single apostrophes, for example:
3047 setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'
3052 - similar to Bourne shell, with control structures like
3053 if...then...else...fi, for...do...done; while...do...done,
3054 until...do...done, ...
3055 - supports environment ("global") variables (through setenv / saveenv
3056 commands) and local shell variables (through standard shell syntax
3057 "name=value"); only environment variables can be used with "run"
3063 (1) If a command line (or an environment variable executed by a "run"
3064 command) contains several commands separated by semicolon, and
3065 one of these commands fails, then the remaining commands will be
3068 (2) If you execute several variables with one call to run (i. e.
3069 calling run with a list of variables as arguments), any failing
3070 command will cause "run" to terminate, i. e. the remaining
3071 variables are not executed.
3073 Note for Redundant Ethernet Interfaces:
3074 =======================================
3076 Some boards come with redundant Ethernet interfaces; U-Boot supports
3077 such configurations and is capable of automatic selection of a
3078 "working" interface when needed. MAC assignment works as follows:
3080 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
3081 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
3082 "eth1addr" (=>eth1), "eth2addr", ...
3084 If the network interface stores some valid MAC address (for instance
3085 in SROM), this is used as default address if there is NO correspon-
3086 ding setting in the environment; if the corresponding environment
3087 variable is set, this overrides the settings in the card; that means:
3089 o If the SROM has a valid MAC address, and there is no address in the
3090 environment, the SROM's address is used.
3092 o If there is no valid address in the SROM, and a definition in the
3093 environment exists, then the value from the environment variable is
3096 o If both the SROM and the environment contain a MAC address, and
3097 both addresses are the same, this MAC address is used.
3099 o If both the SROM and the environment contain a MAC address, and the
3100 addresses differ, the value from the environment is used and a
3103 o If neither SROM nor the environment contain a MAC address, an error
3110 U-Boot is capable of booting (and performing other auxiliary operations on)
3111 images in two formats:
3113 New uImage format (FIT)
3114 -----------------------
3116 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
3117 to Flattened Device Tree). It allows the use of images with multiple
3118 components (several kernels, ramdisks, etc.), with contents protected by
3119 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
3125 Old image format is based on binary files which can be basically anything,
3126 preceded by a special header; see the definitions in include/image.h for
3127 details; basically, the header defines the following image properties:
3129 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
3130 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
3131 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
3132 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
3134 * Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
3135 IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
3136 Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
3137 * Compression Type (uncompressed, gzip, bzip2)
3143 The header is marked by a special Magic Number, and both the header
3144 and the data portions of the image are secured against corruption by
3151 Although U-Boot should support any OS or standalone application
3152 easily, the main focus has always been on Linux during the design of
3155 U-Boot includes many features that so far have been part of some
3156 special "boot loader" code within the Linux kernel. Also, any
3157 "initrd" images to be used are no longer part of one big Linux image;
3158 instead, kernel and "initrd" are separate images. This implementation
3159 serves several purposes:
3161 - the same features can be used for other OS or standalone
3162 applications (for instance: using compressed images to reduce the
3163 Flash memory footprint)
3165 - it becomes much easier to port new Linux kernel versions because
3166 lots of low-level, hardware dependent stuff are done by U-Boot
3168 - the same Linux kernel image can now be used with different "initrd"
3169 images; of course this also means that different kernel images can
3170 be run with the same "initrd". This makes testing easier (you don't
3171 have to build a new "zImage.initrd" Linux image when you just
3172 change a file in your "initrd"). Also, a field-upgrade of the
3173 software is easier now.
3179 Porting Linux to U-Boot based systems:
3180 ---------------------------------------
3182 U-Boot cannot save you from doing all the necessary modifications to
3183 configure the Linux device drivers for use with your target hardware
3184 (no, we don't intend to provide a full virtual machine interface to
3187 But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
3189 Just make sure your machine specific header file (for instance
3190 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
3191 Information structure as we define in include/asm-<arch>/u-boot.h,
3192 and make sure that your definition of IMAP_ADDR uses the same value
3193 as your U-Boot configuration in CONFIG_SYS_IMMR.
3196 Configuring the Linux kernel:
3197 -----------------------------
3199 No specific requirements for U-Boot. Make sure you have some root
3200 device (initial ramdisk, NFS) for your target system.
3203 Building a Linux Image:
3204 -----------------------
3206 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
3207 not used. If you use recent kernel source, a new build target
3208 "uImage" will exist which automatically builds an image usable by
3209 U-Boot. Most older kernels also have support for a "pImage" target,
3210 which was introduced for our predecessor project PPCBoot and uses a
3211 100% compatible format.
3220 The "uImage" build target uses a special tool (in 'tools/mkimage') to
3221 encapsulate a compressed Linux kernel image with header information,
3222 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
3224 * build a standard "vmlinux" kernel image (in ELF binary format):
3226 * convert the kernel into a raw binary image:
3228 ${CROSS_COMPILE}-objcopy -O binary \
3229 -R .note -R .comment \
3230 -S vmlinux linux.bin
3232 * compress the binary image:
3236 * package compressed binary image for U-Boot:
3238 mkimage -A ppc -O linux -T kernel -C gzip \
3239 -a 0 -e 0 -n "Linux Kernel Image" \
3240 -d linux.bin.gz uImage
3243 The "mkimage" tool can also be used to create ramdisk images for use
3244 with U-Boot, either separated from the Linux kernel image, or
3245 combined into one file. "mkimage" encapsulates the images with a 64
3246 byte header containing information about target architecture,
3247 operating system, image type, compression method, entry points, time
3248 stamp, CRC32 checksums, etc.
3250 "mkimage" can be called in two ways: to verify existing images and
3251 print the header information, or to build new images.
3253 In the first form (with "-l" option) mkimage lists the information
3254 contained in the header of an existing U-Boot image; this includes
3255 checksum verification:
3257 tools/mkimage -l image
3258 -l ==> list image header information
3260 The second form (with "-d" option) is used to build a U-Boot image
3261 from a "data file" which is used as image payload:
3263 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
3264 -n name -d data_file image
3265 -A ==> set architecture to 'arch'
3266 -O ==> set operating system to 'os'
3267 -T ==> set image type to 'type'
3268 -C ==> set compression type 'comp'
3269 -a ==> set load address to 'addr' (hex)
3270 -e ==> set entry point to 'ep' (hex)
3271 -n ==> set image name to 'name'
3272 -d ==> use image data from 'datafile'
3274 Right now, all Linux kernels for PowerPC systems use the same load
3275 address (0x00000000), but the entry point address depends on the
3278 - 2.2.x kernels have the entry point at 0x0000000C,
3279 - 2.3.x and later kernels have the entry point at 0x00000000.
3281 So a typical call to build a U-Boot image would read:
3283 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3284 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
3285 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
3286 > examples/uImage.TQM850L
3287 Image Name: 2.4.4 kernel for TQM850L
3288 Created: Wed Jul 19 02:34:59 2000
3289 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3290 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3291 Load Address: 0x00000000
3292 Entry Point: 0x00000000
3294 To verify the contents of the image (or check for corruption):
3296 -> tools/mkimage -l examples/uImage.TQM850L
3297 Image Name: 2.4.4 kernel for TQM850L
3298 Created: Wed Jul 19 02:34:59 2000
3299 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3300 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
3301 Load Address: 0x00000000
3302 Entry Point: 0x00000000
3304 NOTE: for embedded systems where boot time is critical you can trade
3305 speed for memory and install an UNCOMPRESSED image instead: this
3306 needs more space in Flash, but boots much faster since it does not
3307 need to be uncompressed:
3309 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
3310 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
3311 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
3312 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
3313 > examples/uImage.TQM850L-uncompressed
3314 Image Name: 2.4.4 kernel for TQM850L
3315 Created: Wed Jul 19 02:34:59 2000
3316 Image Type: PowerPC Linux Kernel Image (uncompressed)
3317 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
3318 Load Address: 0x00000000
3319 Entry Point: 0x00000000
3322 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
3323 when your kernel is intended to use an initial ramdisk:
3325 -> tools/mkimage -n 'Simple Ramdisk Image' \
3326 > -A ppc -O linux -T ramdisk -C gzip \
3327 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3328 Image Name: Simple Ramdisk Image
3329 Created: Wed Jan 12 14:01:50 2000
3330 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3331 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3332 Load Address: 0x00000000
3333 Entry Point: 0x00000000
3336 Installing a Linux Image:
3337 -------------------------
3339 To downloading a U-Boot image over the serial (console) interface,
3340 you must convert the image to S-Record format:
3342 objcopy -I binary -O srec examples/image examples/image.srec
3344 The 'objcopy' does not understand the information in the U-Boot
3345 image header, so the resulting S-Record file will be relative to
3346 address 0x00000000. To load it to a given address, you need to
3347 specify the target address as 'offset' parameter with the 'loads'
3350 Example: install the image to address 0x40100000 (which on the
3351 TQM8xxL is in the first Flash bank):
3353 => erase 40100000 401FFFFF
3359 ## Ready for S-Record download ...
3360 ~>examples/image.srec
3361 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3363 15989 15990 15991 15992
3364 [file transfer complete]
3366 ## Start Addr = 0x00000000
3369 You can check the success of the download using the 'iminfo' command;
3370 this includes a checksum verification so you can be sure no data
3371 corruption happened:
3375 ## Checking Image at 40100000 ...
3376 Image Name: 2.2.13 for initrd on TQM850L
3377 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3378 Data Size: 335725 Bytes = 327 kB = 0 MB
3379 Load Address: 00000000
3380 Entry Point: 0000000c
3381 Verifying Checksum ... OK
3387 The "bootm" command is used to boot an application that is stored in
3388 memory (RAM or Flash). In case of a Linux kernel image, the contents
3389 of the "bootargs" environment variable is passed to the kernel as
3390 parameters. You can check and modify this variable using the
3391 "printenv" and "setenv" commands:
3394 => printenv bootargs
3395 bootargs=root=/dev/ram
3397 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3399 => printenv bootargs
3400 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3403 ## Booting Linux kernel at 40020000 ...
3404 Image Name: 2.2.13 for NFS on TQM850L
3405 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3406 Data Size: 381681 Bytes = 372 kB = 0 MB
3407 Load Address: 00000000
3408 Entry Point: 0000000c
3409 Verifying Checksum ... OK
3410 Uncompressing Kernel Image ... OK
3411 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
3412 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3413 time_init: decrementer frequency = 187500000/60
3414 Calibrating delay loop... 49.77 BogoMIPS
3415 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3418 If you want to boot a Linux kernel with initial RAM disk, you pass
3419 the memory addresses of both the kernel and the initrd image (PPBCOOT
3420 format!) to the "bootm" command:
3422 => imi 40100000 40200000
3424 ## Checking Image at 40100000 ...
3425 Image Name: 2.2.13 for initrd on TQM850L
3426 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3427 Data Size: 335725 Bytes = 327 kB = 0 MB
3428 Load Address: 00000000
3429 Entry Point: 0000000c
3430 Verifying Checksum ... OK
3432 ## Checking Image at 40200000 ...
3433 Image Name: Simple Ramdisk Image
3434 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3435 Data Size: 566530 Bytes = 553 kB = 0 MB
3436 Load Address: 00000000
3437 Entry Point: 00000000
3438 Verifying Checksum ... OK
3440 => bootm 40100000 40200000
3441 ## Booting Linux kernel at 40100000 ...
3442 Image Name: 2.2.13 for initrd on TQM850L
3443 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3444 Data Size: 335725 Bytes = 327 kB = 0 MB
3445 Load Address: 00000000
3446 Entry Point: 0000000c
3447 Verifying Checksum ... OK
3448 Uncompressing Kernel Image ... OK
3449 ## Loading RAMDisk Image at 40200000 ...
3450 Image Name: Simple Ramdisk Image
3451 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3452 Data Size: 566530 Bytes = 553 kB = 0 MB
3453 Load Address: 00000000
3454 Entry Point: 00000000
3455 Verifying Checksum ... OK
3456 Loading Ramdisk ... OK
3457 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
3458 Boot arguments: root=/dev/ram
3459 time_init: decrementer frequency = 187500000/60
3460 Calibrating delay loop... 49.77 BogoMIPS
3462 RAMDISK: Compressed image found at block 0
3463 VFS: Mounted root (ext2 filesystem).
3467 Boot Linux and pass a flat device tree:
3470 First, U-Boot must be compiled with the appropriate defines. See the section
3471 titled "Linux Kernel Interface" above for a more in depth explanation. The
3472 following is an example of how to start a kernel and pass an updated
3478 oft=oftrees/mpc8540ads.dtb
3479 => tftp $oftaddr $oft
3480 Speed: 1000, full duplex
3482 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3483 Filename 'oftrees/mpc8540ads.dtb'.
3484 Load address: 0x300000
3487 Bytes transferred = 4106 (100a hex)
3488 => tftp $loadaddr $bootfile
3489 Speed: 1000, full duplex
3491 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3493 Load address: 0x200000
3494 Loading:############
3496 Bytes transferred = 1029407 (fb51f hex)
3501 => bootm $loadaddr - $oftaddr
3502 ## Booting image at 00200000 ...
3503 Image Name: Linux-2.6.17-dirty
3504 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3505 Data Size: 1029343 Bytes = 1005.2 kB
3506 Load Address: 00000000
3507 Entry Point: 00000000
3508 Verifying Checksum ... OK
3509 Uncompressing Kernel Image ... OK
3510 Booting using flat device tree at 0x300000
3511 Using MPC85xx ADS machine description
3512 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3516 More About U-Boot Image Types:
3517 ------------------------------
3519 U-Boot supports the following image types:
3521 "Standalone Programs" are directly runnable in the environment
3522 provided by U-Boot; it is expected that (if they behave
3523 well) you can continue to work in U-Boot after return from
3524 the Standalone Program.
3525 "OS Kernel Images" are usually images of some Embedded OS which
3526 will take over control completely. Usually these programs
3527 will install their own set of exception handlers, device
3528 drivers, set up the MMU, etc. - this means, that you cannot
3529 expect to re-enter U-Boot except by resetting the CPU.
3530 "RAMDisk Images" are more or less just data blocks, and their
3531 parameters (address, size) are passed to an OS kernel that is
3533 "Multi-File Images" contain several images, typically an OS
3534 (Linux) kernel image and one or more data images like
3535 RAMDisks. This construct is useful for instance when you want
3536 to boot over the network using BOOTP etc., where the boot
3537 server provides just a single image file, but you want to get
3538 for instance an OS kernel and a RAMDisk image.
3540 "Multi-File Images" start with a list of image sizes, each
3541 image size (in bytes) specified by an "uint32_t" in network
3542 byte order. This list is terminated by an "(uint32_t)0".
3543 Immediately after the terminating 0 follow the images, one by
3544 one, all aligned on "uint32_t" boundaries (size rounded up to
3545 a multiple of 4 bytes).
3547 "Firmware Images" are binary images containing firmware (like
3548 U-Boot or FPGA images) which usually will be programmed to
3551 "Script files" are command sequences that will be executed by
3552 U-Boot's command interpreter; this feature is especially
3553 useful when you configure U-Boot to use a real shell (hush)
3554 as command interpreter.
3560 One of the features of U-Boot is that you can dynamically load and
3561 run "standalone" applications, which can use some resources of
3562 U-Boot like console I/O functions or interrupt services.
3564 Two simple examples are included with the sources:
3569 'examples/hello_world.c' contains a small "Hello World" Demo
3570 application; it is automatically compiled when you build U-Boot.
3571 It's configured to run at address 0x00040004, so you can play with it
3575 ## Ready for S-Record download ...
3576 ~>examples/hello_world.srec
3577 1 2 3 4 5 6 7 8 9 10 11 ...
3578 [file transfer complete]
3580 ## Start Addr = 0x00040004
3582 => go 40004 Hello World! This is a test.
3583 ## Starting application at 0x00040004 ...
3594 Hit any key to exit ...
3596 ## Application terminated, rc = 0x0
3598 Another example, which demonstrates how to register a CPM interrupt
3599 handler with the U-Boot code, can be found in 'examples/timer.c'.
3600 Here, a CPM timer is set up to generate an interrupt every second.
3601 The interrupt service routine is trivial, just printing a '.'
3602 character, but this is just a demo program. The application can be
3603 controlled by the following keys:
3605 ? - print current values og the CPM Timer registers
3606 b - enable interrupts and start timer
3607 e - stop timer and disable interrupts
3608 q - quit application
3611 ## Ready for S-Record download ...
3612 ~>examples/timer.srec
3613 1 2 3 4 5 6 7 8 9 10 11 ...
3614 [file transfer complete]
3616 ## Start Addr = 0x00040004
3619 ## Starting application at 0x00040004 ...
3622 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3625 [q, b, e, ?] Set interval 1000000 us
3628 [q, b, e, ?] ........
3629 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3632 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3635 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3638 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3640 [q, b, e, ?] ...Stopping timer
3642 [q, b, e, ?] ## Application terminated, rc = 0x0
3648 Over time, many people have reported problems when trying to use the
3649 "minicom" terminal emulation program for serial download. I (wd)
3650 consider minicom to be broken, and recommend not to use it. Under
3651 Unix, I recommend to use C-Kermit for general purpose use (and
3652 especially for kermit binary protocol download ("loadb" command), and
3653 use "cu" for S-Record download ("loads" command).
3655 Nevertheless, if you absolutely want to use it try adding this
3656 configuration to your "File transfer protocols" section:
3658 Name Program Name U/D FullScr IO-Red. Multi
3659 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3660 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3666 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3667 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3669 Building requires a cross environment; it is known to work on
3670 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3671 need gmake since the Makefiles are not compatible with BSD make).
3672 Note that the cross-powerpc package does not install include files;
3673 attempting to build U-Boot will fail because <machine/ansi.h> is
3674 missing. This file has to be installed and patched manually:
3676 # cd /usr/pkg/cross/powerpc-netbsd/include
3678 # ln -s powerpc machine
3679 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3680 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3682 Native builds *don't* work due to incompatibilities between native
3683 and U-Boot include files.
3685 Booting assumes that (the first part of) the image booted is a
3686 stage-2 loader which in turn loads and then invokes the kernel
3687 proper. Loader sources will eventually appear in the NetBSD source
3688 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3689 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3692 Implementation Internals:
3693 =========================
3695 The following is not intended to be a complete description of every
3696 implementation detail. However, it should help to understand the
3697 inner workings of U-Boot and make it easier to port it to custom
3701 Initial Stack, Global Data:
3702 ---------------------------
3704 The implementation of U-Boot is complicated by the fact that U-Boot
3705 starts running out of ROM (flash memory), usually without access to
3706 system RAM (because the memory controller is not initialized yet).
3707 This means that we don't have writable Data or BSS segments, and BSS
3708 is not initialized as zero. To be able to get a C environment working
3709 at all, we have to allocate at least a minimal stack. Implementation
3710 options for this are defined and restricted by the CPU used: Some CPU
3711 models provide on-chip memory (like the IMMR area on MPC8xx and
3712 MPC826x processors), on others (parts of) the data cache can be
3713 locked as (mis-) used as memory, etc.
3715 Chris Hallinan posted a good summary of these issues to the
3716 u-boot-users mailing list:
3718 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3719 From: "Chris Hallinan" <clh@net1plus.com>
3720 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3723 Correct me if I'm wrong, folks, but the way I understand it
3724 is this: Using DCACHE as initial RAM for Stack, etc, does not
3725 require any physical RAM backing up the cache. The cleverness
3726 is that the cache is being used as a temporary supply of
3727 necessary storage before the SDRAM controller is setup. It's
3728 beyond the scope of this list to explain the details, but you
3729 can see how this works by studying the cache architecture and
3730 operation in the architecture and processor-specific manuals.
3732 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3733 is another option for the system designer to use as an
3734 initial stack/RAM area prior to SDRAM being available. Either
3735 option should work for you. Using CS 4 should be fine if your
3736 board designers haven't used it for something that would
3737 cause you grief during the initial boot! It is frequently not
3740 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3741 with your processor/board/system design. The default value
3742 you will find in any recent u-boot distribution in
3743 walnut.h should work for you. I'd set it to a value larger
3744 than your SDRAM module. If you have a 64MB SDRAM module, set
3745 it above 400_0000. Just make sure your board has no resources
3746 that are supposed to respond to that address! That code in
3747 start.S has been around a while and should work as is when
3748 you get the config right.
3753 It is essential to remember this, since it has some impact on the C
3754 code for the initialization procedures:
3756 * Initialized global data (data segment) is read-only. Do not attempt
3759 * Do not use any uninitialized global data (or implicitely initialized
3760 as zero data - BSS segment) at all - this is undefined, initiali-
3761 zation is performed later (when relocating to RAM).
3763 * Stack space is very limited. Avoid big data buffers or things like
3766 Having only the stack as writable memory limits means we cannot use
3767 normal global data to share information beween the code. But it
3768 turned out that the implementation of U-Boot can be greatly
3769 simplified by making a global data structure (gd_t) available to all
3770 functions. We could pass a pointer to this data as argument to _all_
3771 functions, but this would bloat the code. Instead we use a feature of
3772 the GCC compiler (Global Register Variables) to share the data: we
3773 place a pointer (gd) to the global data into a register which we
3774 reserve for this purpose.
3776 When choosing a register for such a purpose we are restricted by the
3777 relevant (E)ABI specifications for the current architecture, and by
3778 GCC's implementation.
3780 For PowerPC, the following registers have specific use:
3782 R2: reserved for system use
3783 R3-R4: parameter passing and return values
3784 R5-R10: parameter passing
3785 R13: small data area pointer
3789 (U-Boot also uses R14 as internal GOT pointer.)
3791 ==> U-Boot will use R2 to hold a pointer to the global data
3793 Note: on PPC, we could use a static initializer (since the
3794 address of the global data structure is known at compile time),
3795 but it turned out that reserving a register results in somewhat
3796 smaller code - although the code savings are not that big (on
3797 average for all boards 752 bytes for the whole U-Boot image,
3798 624 text + 127 data).
3800 On Blackfin, the normal C ABI (except for P5) is followed as documented here:
3801 http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface
3803 ==> U-Boot will use P5 to hold a pointer to the global data
3805 On ARM, the following registers are used:
3807 R0: function argument word/integer result
3808 R1-R3: function argument word
3810 R10: stack limit (used only if stack checking if enabled)
3811 R11: argument (frame) pointer
3812 R12: temporary workspace
3815 R15: program counter
3817 ==> U-Boot will use R8 to hold a pointer to the global data
3819 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3820 or current versions of GCC may "optimize" the code too much.
3825 U-Boot runs in system state and uses physical addresses, i.e. the
3826 MMU is not used either for address mapping nor for memory protection.
3828 The available memory is mapped to fixed addresses using the memory
3829 controller. In this process, a contiguous block is formed for each
3830 memory type (Flash, SDRAM, SRAM), even when it consists of several
3831 physical memory banks.
3833 U-Boot is installed in the first 128 kB of the first Flash bank (on
3834 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3835 booting and sizing and initializing DRAM, the code relocates itself
3836 to the upper end of DRAM. Immediately below the U-Boot code some
3837 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3838 configuration setting]. Below that, a structure with global Board
3839 Info data is placed, followed by the stack (growing downward).
3841 Additionally, some exception handler code is copied to the low 8 kB
3842 of DRAM (0x00000000 ... 0x00001FFF).
3844 So a typical memory configuration with 16 MB of DRAM could look like
3847 0x0000 0000 Exception Vector code
3850 0x0000 2000 Free for Application Use
3856 0x00FB FF20 Monitor Stack (Growing downward)
3857 0x00FB FFAC Board Info Data and permanent copy of global data
3858 0x00FC 0000 Malloc Arena
3861 0x00FE 0000 RAM Copy of Monitor Code
3862 ... eventually: LCD or video framebuffer
3863 ... eventually: pRAM (Protected RAM - unchanged by reset)
3864 0x00FF FFFF [End of RAM]
3867 System Initialization:
3868 ----------------------
3870 In the reset configuration, U-Boot starts at the reset entry point
3871 (on most PowerPC systems at address 0x00000100). Because of the reset
3872 configuration for CS0# this is a mirror of the onboard Flash memory.
3873 To be able to re-map memory U-Boot then jumps to its link address.
3874 To be able to implement the initialization code in C, a (small!)
3875 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3876 which provide such a feature like MPC8xx or MPC8260), or in a locked
3877 part of the data cache. After that, U-Boot initializes the CPU core,
3878 the caches and the SIU.
3880 Next, all (potentially) available memory banks are mapped using a
3881 preliminary mapping. For example, we put them on 512 MB boundaries
3882 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3883 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3884 programmed for SDRAM access. Using the temporary configuration, a
3885 simple memory test is run that determines the size of the SDRAM
3888 When there is more than one SDRAM bank, and the banks are of
3889 different size, the largest is mapped first. For equal size, the first
3890 bank (CS2#) is mapped first. The first mapping is always for address
3891 0x00000000, with any additional banks following immediately to create
3892 contiguous memory starting from 0.
3894 Then, the monitor installs itself at the upper end of the SDRAM area
3895 and allocates memory for use by malloc() and for the global Board
3896 Info data; also, the exception vector code is copied to the low RAM
3897 pages, and the final stack is set up.
3899 Only after this relocation will you have a "normal" C environment;
3900 until that you are restricted in several ways, mostly because you are
3901 running from ROM, and because the code will have to be relocated to a
3905 U-Boot Porting Guide:
3906 ----------------------
3908 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3912 int main (int argc, char *argv[])
3914 sighandler_t no_more_time;
3916 signal (SIGALRM, no_more_time);
3917 alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
3919 if (available_money > available_manpower) {
3920 pay consultant to port U-Boot;
3924 Download latest U-Boot source;
3926 Subscribe to u-boot-users mailing list;
3929 email ("Hi, I am new to U-Boot, how do I get started?");
3933 Read the README file in the top level directory;
3934 Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
3935 Read the source, Luke;
3938 if (available_money > toLocalCurrency ($2500)) {
3941 Add a lot of aggravation and time;
3944 Create your own board support subdirectory;
3946 Create your own board config file;
3950 Add / modify source code;
3954 email ("Hi, I am having problems...");
3956 Send patch file to Wolfgang;
3961 void no_more_time (int sig)
3970 All contributions to U-Boot should conform to the Linux kernel
3971 coding style; see the file "Documentation/CodingStyle" and the script
3972 "scripts/Lindent" in your Linux kernel source directory. In sources
3973 originating from U-Boot a style corresponding to "Lindent -pcs" (adding
3974 spaces before parameters to function calls) is actually used.
3976 Source files originating from a different project (for example the
3977 MTD subsystem) are generally exempt from these guidelines and are not
3978 reformated to ease subsequent migration to newer versions of those
3981 Please note that U-Boot is implemented in C (and to some small parts in
3982 Assembler); no C++ is used, so please do not use C++ style comments (//)
3985 Please also stick to the following formatting rules:
3986 - remove any trailing white space
3987 - use TAB characters for indentation, not spaces
3988 - make sure NOT to use DOS '\r\n' line feeds
3989 - do not add more than 2 empty lines to source files
3990 - do not add trailing empty lines to source files
3992 Submissions which do not conform to the standards may be returned
3993 with a request to reformat the changes.
3999 Since the number of patches for U-Boot is growing, we need to
4000 establish some rules. Submissions which do not conform to these rules
4001 may be rejected, even when they contain important and valuable stuff.
4003 Patches shall be sent to the u-boot-users mailing list.
4005 Please see http://www.denx.de/wiki/U-Boot/Patches for details.
4007 When you send a patch, please include the following information with
4010 * For bug fixes: a description of the bug and how your patch fixes
4011 this bug. Please try to include a way of demonstrating that the
4012 patch actually fixes something.
4014 * For new features: a description of the feature and your
4017 * A CHANGELOG entry as plaintext (separate from the patch)
4019 * For major contributions, your entry to the CREDITS file
4021 * When you add support for a new board, don't forget to add this
4022 board to the MAKEALL script, too.
4024 * If your patch adds new configuration options, don't forget to
4025 document these in the README file.
4027 * The patch itself. If you are using git (which is *strongly*
4028 recommended) you can easily generate the patch using the
4029 "git-format-patch". If you then use "git-send-email" to send it to
4030 the U-Boot mailing list, you will avoid most of the common problems
4031 with some other mail clients.
4033 If you cannot use git, use "diff -purN OLD NEW". If your version of
4034 diff does not support these options, then get the latest version of
4037 The current directory when running this command shall be the parent
4038 directory of the U-Boot source tree (i. e. please make sure that
4039 your patch includes sufficient directory information for the
4042 We prefer patches as plain text. MIME attachments are discouraged,
4043 and compressed attachments must not be used.
4045 * If one logical set of modifications affects or creates several
4046 files, all these changes shall be submitted in a SINGLE patch file.
4048 * Changesets that contain different, unrelated modifications shall be
4049 submitted as SEPARATE patches, one patch per changeset.
4054 * Before sending the patch, run the MAKEALL script on your patched
4055 source tree and make sure that no errors or warnings are reported
4056 for any of the boards.
4058 * Keep your modifications to the necessary minimum: A patch
4059 containing several unrelated changes or arbitrary reformats will be
4060 returned with a request to re-formatting / split it.
4062 * If you modify existing code, make sure that your new code does not
4063 add to the memory footprint of the code ;-) Small is beautiful!
4064 When adding new features, these should compile conditionally only
4065 (using #ifdef), and the resulting code with the new feature
4066 disabled must not need more memory than the old code without your
4069 * Remember that there is a size limit of 40 kB per message on the
4070 u-boot-users mailing list. Bigger patches will be moderated. If
4071 they are reasonable and not bigger than 100 kB, they will be
4072 acknowledged. Even bigger patches should be avoided.
projects / u-boot / blob