1 # SPDX-License-Identifier: GPL-2.0+
3 # (C) Copyright 2000 - 2013
4 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
9 This directory contains the source code for U-Boot, a boot loader for
10 Embedded boards based on PowerPC, ARM, MIPS and several other
11 processors, which can be installed in a boot ROM and used to
12 initialize and test the hardware or to download and run application
15 The development of U-Boot is closely related to Linux: some parts of
16 the source code originate in the Linux source tree, we have some
17 header files in common, and special provision has been made to
18 support booting of Linux images.
20 Some attention has been paid to make this software easily
21 configurable and extendable. For instance, all monitor commands are
22 implemented with the same call interface, so that it's very easy to
23 add new commands. Also, instead of permanently adding rarely used
24 code (for instance hardware test utilities) to the monitor, you can
25 load and run it dynamically.
31 In general, all boards for which a configuration option exists in the
32 Makefile have been tested to some extent and can be considered
33 "working". In fact, many of them are used in production systems.
35 In case of problems see the CHANGELOG file to find out who contributed
36 the specific port. In addition, there are various MAINTAINERS files
37 scattered throughout the U-Boot source identifying the people or
38 companies responsible for various boards and subsystems.
40 Note: As of August, 2010, there is no longer a CHANGELOG file in the
41 actual U-Boot source tree; however, it can be created dynamically
42 from the Git log using:
50 In case you have questions about, problems with or contributions for
51 U-Boot, you should send a message to the U-Boot mailing list at
52 <u-boot@lists.denx.de>. There is also an archive of previous traffic
53 on the mailing list - please search the archive before asking FAQ's.
54 Please see https://lists.denx.de/pipermail/u-boot and
55 https://marc.info/?l=u-boot
57 Where to get source code:
58 =========================
60 The U-Boot source code is maintained in the Git repository at
61 https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
62 https://source.denx.de/u-boot/u-boot
64 The "Tags" links on this page allow you to download tarballs of
65 any version you might be interested in. Official releases are also
66 available from the DENX file server through HTTPS or FTP.
67 https://ftp.denx.de/pub/u-boot/
68 ftp://ftp.denx.de/pub/u-boot/
74 - start from 8xxrom sources
75 - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
77 - make it easier to add custom boards
78 - make it possible to add other [PowerPC] CPUs
79 - extend functions, especially:
80 * Provide extended interface to Linux boot loader
83 * ATA disk / SCSI ... boot
84 - create ARMBoot project (https://sourceforge.net/projects/armboot)
85 - add other CPU families (starting with ARM)
86 - create U-Boot project (https://sourceforge.net/projects/u-boot)
87 - current project page: see https://www.denx.de/wiki/U-Boot
93 The "official" name of this project is "Das U-Boot". The spelling
94 "U-Boot" shall be used in all written text (documentation, comments
95 in source files etc.). Example:
97 This is the README file for the U-Boot project.
99 File names etc. shall be based on the string "u-boot". Examples:
101 include/asm-ppc/u-boot.h
103 #include <asm/u-boot.h>
105 Variable names, preprocessor constants etc. shall be either based on
106 the string "u_boot" or on "U_BOOT". Example:
108 U_BOOT_VERSION u_boot_logo
109 IH_OS_U_BOOT u_boot_hush_start
115 Starting with the release in October 2008, the names of the releases
116 were changed from numerical release numbers without deeper meaning
117 into a time stamp based numbering. Regular releases are identified by
118 names consisting of the calendar year and month of the release date.
119 Additional fields (if present) indicate release candidates or bug fix
120 releases in "stable" maintenance trees.
123 U-Boot v2009.11 - Release November 2009
124 U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
125 U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
131 /arch Architecture-specific files
132 /arc Files generic to ARC architecture
133 /arm Files generic to ARM architecture
134 /m68k Files generic to m68k architecture
135 /microblaze Files generic to microblaze architecture
136 /mips Files generic to MIPS architecture
137 /nds32 Files generic to NDS32 architecture
138 /nios2 Files generic to Altera NIOS2 architecture
139 /powerpc Files generic to PowerPC architecture
140 /riscv Files generic to RISC-V architecture
141 /sandbox Files generic to HW-independent "sandbox"
142 /sh Files generic to SH architecture
143 /x86 Files generic to x86 architecture
144 /xtensa Files generic to Xtensa architecture
145 /api Machine/arch-independent API for external apps
146 /board Board-dependent files
147 /boot Support for images and booting
148 /cmd U-Boot commands functions
149 /common Misc architecture-independent functions
150 /configs Board default configuration files
151 /disk Code for disk drive partition handling
152 /doc Documentation (a mix of ReST and READMEs)
153 /drivers Device drivers
154 /dts Makefile for building internal U-Boot fdt.
155 /env Environment support
156 /examples Example code for standalone applications, etc.
157 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
158 /include Header Files
159 /lib Library routines generic to all architectures
160 /Licenses Various license files
162 /post Power On Self Test
163 /scripts Various build scripts and Makefiles
164 /test Various unit test files
165 /tools Tools to build and sign FIT images, etc.
167 Software Configuration:
168 =======================
170 Configuration is usually done using C preprocessor defines; the
171 rationale behind that is to avoid dead code whenever possible.
173 There are two classes of configuration variables:
175 * Configuration _OPTIONS_:
176 These are selectable by the user and have names beginning with
179 * Configuration _SETTINGS_:
180 These depend on the hardware etc. and should not be meddled with if
181 you don't know what you're doing; they have names beginning with
184 Previously, all configuration was done by hand, which involved creating
185 symbolic links and editing configuration files manually. More recently,
186 U-Boot has added the Kbuild infrastructure used by the Linux kernel,
187 allowing you to use the "make menuconfig" command to configure your
191 Selection of Processor Architecture and Board Type:
192 ---------------------------------------------------
194 For all supported boards there are ready-to-use default
195 configurations available; just type "make <board_name>_defconfig".
197 Example: For a TQM823L module type:
200 make TQM823L_defconfig
202 Note: If you're looking for the default configuration file for a board
203 you're sure used to be there but is now missing, check the file
204 doc/README.scrapyard for a list of no longer supported boards.
209 U-Boot can be built natively to run on a Linux host using the 'sandbox'
210 board. This allows feature development which is not board- or architecture-
211 specific to be undertaken on a native platform. The sandbox is also used to
212 run some of U-Boot's tests.
214 See doc/arch/sandbox.rst for more details.
217 Board Initialisation Flow:
218 --------------------------
220 This is the intended start-up flow for boards. This should apply for both
221 SPL and U-Boot proper (i.e. they both follow the same rules).
223 Note: "SPL" stands for "Secondary Program Loader," which is explained in
224 more detail later in this file.
226 At present, SPL mostly uses a separate code path, but the function names
227 and roles of each function are the same. Some boards or architectures
228 may not conform to this. At least most ARM boards which use
229 CONFIG_SPL_FRAMEWORK conform to this.
231 Execution typically starts with an architecture-specific (and possibly
232 CPU-specific) start.S file, such as:
234 - arch/arm/cpu/armv7/start.S
235 - arch/powerpc/cpu/mpc83xx/start.S
236 - arch/mips/cpu/start.S
238 and so on. From there, three functions are called; the purpose and
239 limitations of each of these functions are described below.
242 - purpose: essential init to permit execution to reach board_init_f()
243 - no global_data or BSS
244 - there is no stack (ARMv7 may have one but it will soon be removed)
245 - must not set up SDRAM or use console
246 - must only do the bare minimum to allow execution to continue to
248 - this is almost never needed
249 - return normally from this function
252 - purpose: set up the machine ready for running board_init_r():
253 i.e. SDRAM and serial UART
254 - global_data is available
256 - BSS is not available, so you cannot use global/static variables,
257 only stack variables and global_data
259 Non-SPL-specific notes:
260 - dram_init() is called to set up DRAM. If already done in SPL this
264 - you can override the entire board_init_f() function with your own
266 - preloader_console_init() can be called here in extremis
267 - should set up SDRAM, and anything needed to make the UART work
268 - there is no need to clear BSS, it will be done by crt0.S
269 - for specific scenarios on certain architectures an early BSS *can*
270 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
271 of BSS prior to entering board_init_f()) but doing so is discouraged.
272 Instead it is strongly recommended to architect any code changes
273 or additions such to not depend on the availability of BSS during
274 board_init_f() as indicated in other sections of this README to
275 maintain compatibility and consistency across the entire code base.
276 - must return normally from this function (don't call board_init_r()
279 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
280 this point the stack and global_data are relocated to below
281 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
285 - purpose: main execution, common code
286 - global_data is available
288 - BSS is available, all static/global variables can be used
289 - execution eventually continues to main_loop()
291 Non-SPL-specific notes:
292 - U-Boot is relocated to the top of memory and is now running from
296 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
297 CONFIG_SPL_STACK_R_ADDR points into SDRAM
298 - preloader_console_init() can be called here - typically this is
299 done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
300 spl_board_init() function containing this call
301 - loads U-Boot or (in falcon mode) Linux
304 Configuration Options:
305 ----------------------
307 Configuration depends on the combination of board and CPU type; all
308 such information is kept in a configuration file
309 "include/configs/<board_name>.h".
311 Example: For a TQM823L module, all configuration settings are in
312 "include/configs/TQM823L.h".
315 Many of the options are named exactly as the corresponding Linux
316 kernel configuration options. The intention is to make it easier to
317 build a config tool - later.
319 - ARM Platform Bus Type(CCI):
320 CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
321 provides full cache coherency between two clusters of multi-core
322 CPUs and I/O coherency for devices and I/O masters
324 CONFIG_SYS_FSL_HAS_CCI400
326 Defined For SoC that has cache coherent interconnect
329 CONFIG_SYS_FSL_HAS_CCN504
331 Defined for SoC that has cache coherent interconnect CCN-504
333 The following options need to be configured:
335 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
337 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
342 Specifies that the core is a 64-bit PowerPC implementation (implements
343 the "64" category of the Power ISA). This is necessary for ePAPR
344 compliance, among other possible reasons.
346 CONFIG_SYS_FSL_TBCLK_DIV
348 Defines the core time base clock divider ratio compared to the
349 system clock. On most PQ3 devices this is 8, on newer QorIQ
350 devices it can be 16 or 32. The ratio varies from SoC to Soc.
352 CONFIG_SYS_FSL_PCIE_COMPAT
354 Defines the string to utilize when trying to match PCIe device
355 tree nodes for the given platform.
357 CONFIG_SYS_FSL_ERRATUM_A004510
359 Enables a workaround for erratum A004510. If set,
360 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
361 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
363 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
364 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
366 Defines one or two SoC revisions (low 8 bits of SVR)
367 for which the A004510 workaround should be applied.
369 The rest of SVR is either not relevant to the decision
370 of whether the erratum is present (e.g. p2040 versus
371 p2041) or is implied by the build target, which controls
372 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
374 See Freescale App Note 4493 for more information about
377 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
379 This is the value to write into CCSR offset 0x18600
380 according to the A004510 workaround.
382 CONFIG_SYS_FSL_DSP_DDR_ADDR
383 This value denotes start offset of DDR memory which is
384 connected exclusively to the DSP cores.
386 CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
387 This value denotes start offset of M2 memory
388 which is directly connected to the DSP core.
390 CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
391 This value denotes start offset of M3 memory which is directly
392 connected to the DSP core.
394 CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
395 This value denotes start offset of DSP CCSR space.
397 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
398 Single Source Clock is clocking mode present in some of FSL SoC's.
399 In this mode, a single differential clock is used to supply
400 clocks to the sysclock, ddrclock and usbclock.
402 CONFIG_SYS_CPC_REINIT_F
403 This CONFIG is defined when the CPC is configured as SRAM at the
404 time of U-Boot entry and is required to be re-initialized.
407 Indicates this SoC supports deep sleep feature. If deep sleep is
408 supported, core will start to execute uboot when wakes up.
410 - Generic CPU options:
411 CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
413 Defines the endianess of the CPU. Implementation of those
414 values is arch specific.
417 Freescale DDR driver in use. This type of DDR controller is
418 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
420 CONFIG_SYS_FSL_DDR_ADDR
421 Freescale DDR memory-mapped register base.
423 CONFIG_SYS_FSL_DDR_EMU
424 Specify emulator support for DDR. Some DDR features such as
425 deskew training are not available.
427 CONFIG_SYS_FSL_DDRC_GEN1
428 Freescale DDR1 controller.
430 CONFIG_SYS_FSL_DDRC_GEN2
431 Freescale DDR2 controller.
433 CONFIG_SYS_FSL_DDRC_GEN3
434 Freescale DDR3 controller.
436 CONFIG_SYS_FSL_DDRC_GEN4
437 Freescale DDR4 controller.
439 CONFIG_SYS_FSL_DDRC_ARM_GEN3
440 Freescale DDR3 controller for ARM-based SoCs.
443 Board config to use DDR1. It can be enabled for SoCs with
444 Freescale DDR1 or DDR2 controllers, depending on the board
448 Board config to use DDR2. It can be enabled for SoCs with
449 Freescale DDR2 or DDR3 controllers, depending on the board
453 Board config to use DDR3. It can be enabled for SoCs with
454 Freescale DDR3 or DDR3L controllers.
457 Board config to use DDR3L. It can be enabled for SoCs with
460 CONFIG_SYS_FSL_IFC_BE
461 Defines the IFC controller register space as Big Endian
463 CONFIG_SYS_FSL_IFC_LE
464 Defines the IFC controller register space as Little Endian
466 CONFIG_SYS_FSL_IFC_CLK_DIV
467 Defines divider of platform clock(clock input to IFC controller).
469 CONFIG_SYS_FSL_LBC_CLK_DIV
470 Defines divider of platform clock(clock input to eLBC controller).
472 CONFIG_SYS_FSL_DDR_BE
473 Defines the DDR controller register space as Big Endian
475 CONFIG_SYS_FSL_DDR_LE
476 Defines the DDR controller register space as Little Endian
478 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
479 Physical address from the view of DDR controllers. It is the
480 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
481 it could be different for ARM SoCs.
483 CONFIG_SYS_FSL_DDR_INTLV_256B
484 DDR controller interleaving on 256-byte. This is a special
485 interleaving mode, handled by Dickens for Freescale layerscape
488 CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
489 Number of controllers used as main memory.
491 CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
492 Number of controllers used for other than main memory.
494 CONFIG_SYS_FSL_HAS_DP_DDR
495 Defines the SoC has DP-DDR used for DPAA.
497 CONFIG_SYS_FSL_SEC_BE
498 Defines the SEC controller register space as Big Endian
500 CONFIG_SYS_FSL_SEC_LE
501 Defines the SEC controller register space as Little Endian
504 CONFIG_SYS_INIT_SP_OFFSET
506 Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
507 pointer. This is needed for the temporary stack before
510 CONFIG_XWAY_SWAP_BYTES
512 Enable compilation of tools/xway-swap-bytes needed for Lantiq
513 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
514 be swapped if a flash programmer is used.
517 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
519 Select high exception vectors of the ARM core, e.g., do not
520 clear the V bit of the c1 register of CP15.
523 Generic timer clock source frequency.
525 COUNTER_FREQUENCY_REAL
526 Generic timer clock source frequency if the real clock is
527 different from COUNTER_FREQUENCY, and can only be determined
531 CONFIG_TEGRA_SUPPORT_NON_SECURE
533 Support executing U-Boot in non-secure (NS) mode. Certain
534 impossible actions will be skipped if the CPU is in NS mode,
535 such as ARM architectural timer initialization.
537 - Linux Kernel Interface:
538 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
540 When transferring memsize parameter to Linux, some versions
541 expect it to be in bytes, others in MB.
542 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
546 New kernel versions are expecting firmware settings to be
547 passed using flattened device trees (based on open firmware
551 * New libfdt-based support
552 * Adds the "fdt" command
553 * The bootm command automatically updates the fdt
555 OF_TBCLK - The timebase frequency.
557 boards with QUICC Engines require OF_QE to set UCC MAC
562 U-Boot can detect if an IDE device is present or not.
563 If not, and this new config option is activated, U-Boot
564 removes the ATA node from the DTS before booting Linux,
565 so the Linux IDE driver does not probe the device and
566 crash. This is needed for buggy hardware (uc101) where
567 no pull down resistor is connected to the signal IDE5V_DD7.
569 - vxWorks boot parameters:
571 bootvx constructs a valid bootline using the following
572 environments variables: bootdev, bootfile, ipaddr, netmask,
573 serverip, gatewayip, hostname, othbootargs.
574 It loads the vxWorks image pointed bootfile.
576 Note: If a "bootargs" environment is defined, it will override
577 the defaults discussed just above.
579 - Cache Configuration for ARM:
580 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
582 CONFIG_SYS_PL310_BASE - Physical base address of PL310
583 controller register space
588 If you have Amba PrimeCell PL011 UARTs, set this variable to
589 the clock speed of the UARTs.
593 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
594 define this to a list of base addresses for each (supported)
595 port. See e.g. include/configs/versatile.h
597 CONFIG_SERIAL_HW_FLOW_CONTROL
599 Define this variable to enable hw flow control in serial driver.
600 Current user of this option is drivers/serial/nsl16550.c driver
602 - Serial Download Echo Mode:
604 If defined to 1, all characters received during a
605 serial download (using the "loads" command) are
606 echoed back. This might be needed by some terminal
607 emulations (like "cu"), but may as well just take
608 time on others. This setting #define's the initial
609 value of the "loads_echo" environment variable.
611 - Removal of commands
612 If no commands are needed to boot, you can disable
613 CONFIG_CMDLINE to remove them. In this case, the command line
614 will not be available, and when U-Boot wants to execute the
615 boot command (on start-up) it will call board_run_command()
616 instead. This can reduce image size significantly for very
617 simple boot procedures.
619 - Regular expression support:
621 If this variable is defined, U-Boot is linked against
622 the SLRE (Super Light Regular Expression) library,
623 which adds regex support to some commands, as for
624 example "env grep" and "setexpr".
627 CONFIG_SYS_WATCHDOG_FREQ
628 Some platforms automatically call WATCHDOG_RESET()
629 from the timer interrupt handler every
630 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
631 board configuration file, a default of CONFIG_SYS_HZ/2
632 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
633 to 0 disables calling WATCHDOG_RESET() from the timer
638 When CONFIG_CMD_DATE is selected, the type of the RTC
639 has to be selected, too. Define exactly one of the
642 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
643 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
644 CONFIG_RTC_MC146818 - use MC146818 RTC
645 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
646 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
647 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
648 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
649 CONFIG_RTC_DS164x - use Dallas DS164x RTC
650 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
651 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
652 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
653 CONFIG_SYS_RV3029_TCR - enable trickle charger on
656 Note that if the RTC uses I2C, then the I2C interface
657 must also be configured. See I2C Support, below.
660 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
662 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
663 chip-ngpio pairs that tell the PCA953X driver the number of
664 pins supported by a particular chip.
666 Note that if the GPIO device uses I2C, then the I2C interface
667 must also be configured. See I2C Support, below.
670 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
671 accesses and can checksum them or write a list of them out
672 to memory. See the 'iotrace' command for details. This is
673 useful for testing device drivers since it can confirm that
674 the driver behaves the same way before and after a code
675 change. Currently this is supported on sandbox and arm. To
676 add support for your architecture, add '#include <iotrace.h>'
677 to the bottom of arch/<arch>/include/asm/io.h and test.
679 Example output from the 'iotrace stats' command is below.
680 Note that if the trace buffer is exhausted, the checksum will
681 still continue to operate.
684 Start: 10000000 (buffer start address)
685 Size: 00010000 (buffer size)
686 Offset: 00000120 (current buffer offset)
687 Output: 10000120 (start + offset)
688 Count: 00000018 (number of trace records)
689 CRC32: 9526fb66 (CRC32 of all trace records)
693 When CONFIG_TIMESTAMP is selected, the timestamp
694 (date and time) of an image is printed by image
695 commands like bootm or iminfo. This option is
696 automatically enabled when you select CONFIG_CMD_DATE .
698 - Partition Labels (disklabels) Supported:
699 Zero or more of the following:
700 CONFIG_MAC_PARTITION Apple's MacOS partition table.
701 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
702 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
703 bootloader. Note 2TB partition limit; see
705 CONFIG_SCSI) you must configure support for at
706 least one non-MTD partition type as well.
711 Set this to enable support for disks larger than 137GB
712 Also look at CONFIG_SYS_64BIT_LBA.
713 Whithout these , LBA48 support uses 32bit variables and will 'only'
714 support disks up to 2.1TB.
716 CONFIG_SYS_64BIT_LBA:
717 When enabled, makes the IDE subsystem use 64bit sector addresses.
720 - NETWORK Support (PCI):
722 Utility code for direct access to the SPI bus on Intel 8257x.
723 This does not do anything useful unless you set at least one
724 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
727 Support for National dp83815 chips.
730 Support for National dp8382[01] gigabit chips.
732 - NETWORK Support (other):
734 Support for the Calxeda XGMAC device
737 Support for SMSC's LAN91C96 chips.
739 CONFIG_LAN91C96_USE_32_BIT
740 Define this to enable 32 bit addressing
743 Support for SMSC's LAN91C111 chip
746 Define this to hold the physical address
747 of the device (I/O space)
749 CONFIG_SMC_USE_32_BIT
750 Define this if data bus is 32 bits
752 CONFIG_SMC_USE_IOFUNCS
753 Define this to use i/o functions instead of macros
754 (some hardware wont work with macros)
756 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
757 Define this if you have more then 3 PHYs.
760 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
762 CONFIG_FTGMAC100_EGIGA
763 Define this to use GE link update with gigabit PHY.
764 Define this if FTGMAC100 is connected to gigabit PHY.
765 If your system has 10/100 PHY only, it might not occur
766 wrong behavior. Because PHY usually return timeout or
767 useless data when polling gigabit status and gigabit
768 control registers. This behavior won't affect the
769 correctnessof 10/100 link speed update.
772 Support for Renesas on-chip Ethernet controller
774 CONFIG_SH_ETHER_USE_PORT
775 Define the number of ports to be used
777 CONFIG_SH_ETHER_PHY_ADDR
778 Define the ETH PHY's address
780 CONFIG_SH_ETHER_CACHE_WRITEBACK
781 If this option is set, the driver enables cache flush.
787 CONFIG_TPM_TIS_INFINEON
788 Support for Infineon i2c bus TPM devices. Only one device
789 per system is supported at this time.
791 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
792 Define the burst count bytes upper limit
795 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
797 CONFIG_TPM_ST33ZP24_I2C
798 Support for STMicroelectronics ST33ZP24 I2C devices.
799 Requires TPM_ST33ZP24 and I2C.
801 CONFIG_TPM_ST33ZP24_SPI
802 Support for STMicroelectronics ST33ZP24 SPI devices.
803 Requires TPM_ST33ZP24 and SPI.
806 Support for Atmel TWI TPM device. Requires I2C support.
809 Support for generic parallel port TPM devices. Only one device
810 per system is supported at this time.
812 CONFIG_TPM_TIS_BASE_ADDRESS
813 Base address where the generic TPM device is mapped
814 to. Contemporary x86 systems usually map it at
818 Define this to enable the TPM support library which provides
819 functional interfaces to some TPM commands.
820 Requires support for a TPM device.
822 CONFIG_TPM_AUTH_SESSIONS
823 Define this to enable authorized functions in the TPM library.
824 Requires CONFIG_TPM and CONFIG_SHA1.
827 At the moment only the UHCI host controller is
828 supported (PIP405, MIP405); define
829 CONFIG_USB_UHCI to enable it.
830 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
831 and define CONFIG_USB_STORAGE to enable the USB
834 Supported are USB Keyboards and USB Floppy drives
837 CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
838 txfilltuning field in the EHCI controller on reset.
840 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
844 Define the below if you wish to use the USB console.
845 Once firmware is rebuilt from a serial console issue the
846 command "setenv stdin usbtty; setenv stdout usbtty" and
847 attach your USB cable. The Unix command "dmesg" should print
848 it has found a new device. The environment variable usbtty
849 can be set to gserial or cdc_acm to enable your device to
850 appear to a USB host as a Linux gserial device or a
851 Common Device Class Abstract Control Model serial device.
852 If you select usbtty = gserial you should be able to enumerate
854 # modprobe usbserial vendor=0xVendorID product=0xProductID
855 else if using cdc_acm, simply setting the environment
856 variable usbtty to be cdc_acm should suffice. The following
857 might be defined in YourBoardName.h
860 Define this to build a UDC device
863 Define this to have a tty type of device available to
864 talk to the UDC device
867 Define this to enable the high speed support for usb
868 device and usbtty. If this feature is enabled, a routine
869 int is_usbd_high_speed(void)
870 also needs to be defined by the driver to dynamically poll
871 whether the enumeration has succeded at high speed or full
874 If you have a USB-IF assigned VendorID then you may wish to
875 define your own vendor specific values either in BoardName.h
876 or directly in usbd_vendor_info.h. If you don't define
877 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
878 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
879 should pretend to be a Linux device to it's target host.
881 CONFIG_USBD_MANUFACTURER
882 Define this string as the name of your company for
883 - CONFIG_USBD_MANUFACTURER "my company"
885 CONFIG_USBD_PRODUCT_NAME
886 Define this string as the name of your product
887 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
890 Define this as your assigned Vendor ID from the USB
891 Implementors Forum. This *must* be a genuine Vendor ID
892 to avoid polluting the USB namespace.
893 - CONFIG_USBD_VENDORID 0xFFFF
895 CONFIG_USBD_PRODUCTID
896 Define this as the unique Product ID
898 - CONFIG_USBD_PRODUCTID 0xFFFF
900 - ULPI Layer Support:
901 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
902 the generic ULPI layer. The generic layer accesses the ULPI PHY
903 via the platform viewport, so you need both the genric layer and
904 the viewport enabled. Currently only Chipidea/ARC based
905 viewport is supported.
906 To enable the ULPI layer support, define CONFIG_USB_ULPI and
907 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
908 If your ULPI phy needs a different reference clock than the
909 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
910 the appropriate value in Hz.
913 The MMC controller on the Intel PXA is supported. To
914 enable this define CONFIG_MMC. The MMC can be
915 accessed from the boot prompt by mapping the device
916 to physical memory similar to flash. Command line is
917 enabled with CONFIG_CMD_MMC. The MMC driver also works with
918 the FAT fs. This is enabled with CONFIG_CMD_FAT.
921 Support for Renesas on-chip MMCIF controller
924 Define the base address of MMCIF registers
927 Define the clock frequency for MMCIF
929 - USB Device Firmware Update (DFU) class support:
931 This enables the USB portion of the DFU USB class
934 This enables support for exposing NAND devices via DFU.
937 This enables support for exposing RAM via DFU.
938 Note: DFU spec refer to non-volatile memory usage, but
939 allow usages beyond the scope of spec - here RAM usage,
940 one that would help mostly the developer.
942 CONFIG_SYS_DFU_DATA_BUF_SIZE
943 Dfu transfer uses a buffer before writing data to the
944 raw storage device. Make the size (in bytes) of this buffer
945 configurable. The size of this buffer is also configurable
946 through the "dfu_bufsiz" environment variable.
948 CONFIG_SYS_DFU_MAX_FILE_SIZE
949 When updating files rather than the raw storage device,
950 we use a static buffer to copy the file into and then write
951 the buffer once we've been given the whole file. Define
952 this to the maximum filesize (in bytes) for the buffer.
953 Default is 4 MiB if undefined.
955 DFU_DEFAULT_POLL_TIMEOUT
956 Poll timeout [ms], is the timeout a device can send to the
957 host. The host must wait for this timeout before sending
958 a subsequent DFU_GET_STATUS request to the device.
960 DFU_MANIFEST_POLL_TIMEOUT
961 Poll timeout [ms], which the device sends to the host when
962 entering dfuMANIFEST state. Host waits this timeout, before
963 sending again an USB request to the device.
965 - Journaling Flash filesystem support:
966 CONFIG_SYS_JFFS2_FIRST_SECTOR,
967 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
968 Define these for a default partition on a NOR device
971 See Kconfig help for available keyboard drivers.
975 Enable the Freescale DIU video driver. Reference boards for
976 SOCs that have a DIU should define this macro to enable DIU
977 support, and should also define these other macros:
982 CONFIG_VIDEO_SW_CURSOR
983 CONFIG_VGA_AS_SINGLE_DEVICE
984 CONFIG_VIDEO_BMP_LOGO
986 The DIU driver will look for the 'video-mode' environment
987 variable, and if defined, enable the DIU as a console during
988 boot. See the documentation file doc/README.video for a
989 description of this variable.
991 - LCD Support: CONFIG_LCD
993 Define this to enable LCD support (for output to LCD
994 display); also select one of the supported displays
995 by defining one of these:
999 HITACHI TX09D70VM1CCA, 3.5", 240x320.
1001 CONFIG_NEC_NL6448AC33:
1003 NEC NL6448AC33-18. Active, color, single scan.
1005 CONFIG_NEC_NL6448BC20
1007 NEC NL6448BC20-08. 6.5", 640x480.
1008 Active, color, single scan.
1010 CONFIG_NEC_NL6448BC33_54
1012 NEC NL6448BC33-54. 10.4", 640x480.
1013 Active, color, single scan.
1017 Sharp 320x240. Active, color, single scan.
1018 It isn't 16x9, and I am not sure what it is.
1020 CONFIG_SHARP_LQ64D341
1022 Sharp LQ64D341 display, 640x480.
1023 Active, color, single scan.
1027 HLD1045 display, 640x480.
1028 Active, color, single scan.
1032 Optrex CBL50840-2 NF-FW 99 22 M5
1034 Hitachi LMG6912RPFC-00T
1038 320x240. Black & white.
1040 CONFIG_LCD_ALIGNMENT
1042 Normally the LCD is page-aligned (typically 4KB). If this is
1043 defined then the LCD will be aligned to this value instead.
1044 For ARM it is sometimes useful to use MMU_SECTION_SIZE
1045 here, since it is cheaper to change data cache settings on
1046 a per-section basis.
1051 Sometimes, for example if the display is mounted in portrait
1052 mode or even if it's mounted landscape but rotated by 180degree,
1053 we need to rotate our content of the display relative to the
1054 framebuffer, so that user can read the messages which are
1056 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
1057 initialized with a given rotation from "vl_rot" out of
1058 "vidinfo_t" which is provided by the board specific code.
1059 The value for vl_rot is coded as following (matching to
1060 fbcon=rotate:<n> linux-kernel commandline):
1061 0 = no rotation respectively 0 degree
1062 1 = 90 degree rotation
1063 2 = 180 degree rotation
1064 3 = 270 degree rotation
1066 If CONFIG_LCD_ROTATION is not defined, the console will be
1067 initialized with 0degree rotation.
1071 Support drawing of RLE8-compressed bitmaps on the LCD.
1074 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
1076 The clock frequency of the MII bus
1078 CONFIG_PHY_RESET_DELAY
1080 Some PHY like Intel LXT971A need extra delay after
1081 reset before any MII register access is possible.
1082 For such PHY, set this option to the usec delay
1083 required. (minimum 300usec for LXT971A)
1085 CONFIG_PHY_CMD_DELAY (ppc4xx)
1087 Some PHY like Intel LXT971A need extra delay after
1088 command issued before MII status register can be read
1093 Define a default value for the IP address to use for
1094 the default Ethernet interface, in case this is not
1095 determined through e.g. bootp.
1096 (Environment variable "ipaddr")
1098 - Server IP address:
1101 Defines a default value for the IP address of a TFTP
1102 server to contact when using the "tftboot" command.
1103 (Environment variable "serverip")
1105 - Gateway IP address:
1108 Defines a default value for the IP address of the
1109 default router where packets to other networks are
1111 (Environment variable "gatewayip")
1116 Defines a default value for the subnet mask (or
1117 routing prefix) which is used to determine if an IP
1118 address belongs to the local subnet or needs to be
1119 forwarded through a router.
1120 (Environment variable "netmask")
1122 - BOOTP Recovery Mode:
1123 CONFIG_BOOTP_RANDOM_DELAY
1125 If you have many targets in a network that try to
1126 boot using BOOTP, you may want to avoid that all
1127 systems send out BOOTP requests at precisely the same
1128 moment (which would happen for instance at recovery
1129 from a power failure, when all systems will try to
1130 boot, thus flooding the BOOTP server. Defining
1131 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
1132 inserted before sending out BOOTP requests. The
1133 following delays are inserted then:
1135 1st BOOTP request: delay 0 ... 1 sec
1136 2nd BOOTP request: delay 0 ... 2 sec
1137 3rd BOOTP request: delay 0 ... 4 sec
1139 BOOTP requests: delay 0 ... 8 sec
1141 CONFIG_BOOTP_ID_CACHE_SIZE
1143 BOOTP packets are uniquely identified using a 32-bit ID. The
1144 server will copy the ID from client requests to responses and
1145 U-Boot will use this to determine if it is the destination of
1146 an incoming response. Some servers will check that addresses
1147 aren't in use before handing them out (usually using an ARP
1148 ping) and therefore take up to a few hundred milliseconds to
1149 respond. Network congestion may also influence the time it
1150 takes for a response to make it back to the client. If that
1151 time is too long, U-Boot will retransmit requests. In order
1152 to allow earlier responses to still be accepted after these
1153 retransmissions, U-Boot's BOOTP client keeps a small cache of
1154 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
1155 cache. The default is to keep IDs for up to four outstanding
1156 requests. Increasing this will allow U-Boot to accept offers
1157 from a BOOTP client in networks with unusually high latency.
1159 - DHCP Advanced Options:
1161 - Link-local IP address negotiation:
1162 Negotiate with other link-local clients on the local network
1163 for an address that doesn't require explicit configuration.
1164 This is especially useful if a DHCP server cannot be guaranteed
1165 to exist in all environments that the device must operate.
1167 See doc/README.link-local for more information.
1169 - MAC address from environment variables
1171 FDT_SEQ_MACADDR_FROM_ENV
1173 Fix-up device tree with MAC addresses fetched sequentially from
1174 environment variables. This config work on assumption that
1175 non-usable ethernet node of device-tree are either not present
1176 or their status has been marked as "disabled".
1179 CONFIG_CDP_DEVICE_ID
1181 The device id used in CDP trigger frames.
1183 CONFIG_CDP_DEVICE_ID_PREFIX
1185 A two character string which is prefixed to the MAC address
1190 A printf format string which contains the ascii name of
1191 the port. Normally is set to "eth%d" which sets
1192 eth0 for the first Ethernet, eth1 for the second etc.
1194 CONFIG_CDP_CAPABILITIES
1196 A 32bit integer which indicates the device capabilities;
1197 0x00000010 for a normal host which does not forwards.
1201 An ascii string containing the version of the software.
1205 An ascii string containing the name of the platform.
1209 A 32bit integer sent on the trigger.
1211 CONFIG_CDP_POWER_CONSUMPTION
1213 A 16bit integer containing the power consumption of the
1214 device in .1 of milliwatts.
1216 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1218 A byte containing the id of the VLAN.
1220 - Status LED: CONFIG_LED_STATUS
1222 Several configurations allow to display the current
1223 status using a LED. For instance, the LED will blink
1224 fast while running U-Boot code, stop blinking as
1225 soon as a reply to a BOOTP request was received, and
1226 start blinking slow once the Linux kernel is running
1227 (supported by a status LED driver in the Linux
1228 kernel). Defining CONFIG_LED_STATUS enables this
1233 CONFIG_LED_STATUS_GPIO
1234 The status LED can be connected to a GPIO pin.
1235 In such cases, the gpio_led driver can be used as a
1236 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1237 to include the gpio_led driver in the U-Boot binary.
1239 CONFIG_GPIO_LED_INVERTED_TABLE
1240 Some GPIO connected LEDs may have inverted polarity in which
1241 case the GPIO high value corresponds to LED off state and
1242 GPIO low value corresponds to LED on state.
1243 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1244 with a list of GPIO LEDs that have inverted polarity.
1247 CONFIG_SYS_NUM_I2C_BUSES
1248 Hold the number of i2c buses you want to use.
1250 CONFIG_SYS_I2C_DIRECT_BUS
1251 define this, if you don't use i2c muxes on your hardware.
1252 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1255 CONFIG_SYS_I2C_MAX_HOPS
1256 define how many muxes are maximal consecutively connected
1257 on one i2c bus. If you not use i2c muxes, omit this
1260 CONFIG_SYS_I2C_BUSES
1261 hold a list of buses you want to use, only used if
1262 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1263 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1264 CONFIG_SYS_NUM_I2C_BUSES = 9:
1266 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1267 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1268 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1269 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1270 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1271 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1272 {1, {I2C_NULL_HOP}}, \
1273 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1274 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1278 bus 0 on adapter 0 without a mux
1279 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1280 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1281 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1282 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1283 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1284 bus 6 on adapter 1 without a mux
1285 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1286 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1288 If you do not have i2c muxes on your board, omit this define.
1290 - Legacy I2C Support:
1291 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1292 then the following macros need to be defined (examples are
1293 from include/configs/lwmon.h):
1297 (Optional). Any commands necessary to enable the I2C
1298 controller or configure ports.
1300 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1304 The code necessary to make the I2C data line active
1305 (driven). If the data line is open collector, this
1308 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1312 The code necessary to make the I2C data line tri-stated
1313 (inactive). If the data line is open collector, this
1316 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1320 Code that returns true if the I2C data line is high,
1323 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1327 If <bit> is true, sets the I2C data line high. If it
1328 is false, it clears it (low).
1330 eg: #define I2C_SDA(bit) \
1331 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1332 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1336 If <bit> is true, sets the I2C clock line high. If it
1337 is false, it clears it (low).
1339 eg: #define I2C_SCL(bit) \
1340 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1341 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1345 This delay is invoked four times per clock cycle so this
1346 controls the rate of data transfer. The data rate thus
1347 is 1 / (I2C_DELAY * 4). Often defined to be something
1350 #define I2C_DELAY udelay(2)
1352 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1354 If your arch supports the generic GPIO framework (asm/gpio.h),
1355 then you may alternatively define the two GPIOs that are to be
1356 used as SCL / SDA. Any of the previous I2C_xxx macros will
1357 have GPIO-based defaults assigned to them as appropriate.
1359 You should define these to the GPIO value as given directly to
1360 the generic GPIO functions.
1362 CONFIG_SYS_I2C_INIT_BOARD
1364 When a board is reset during an i2c bus transfer
1365 chips might think that the current transfer is still
1366 in progress. On some boards it is possible to access
1367 the i2c SCLK line directly, either by using the
1368 processor pin as a GPIO or by having a second pin
1369 connected to the bus. If this option is defined a
1370 custom i2c_init_board() routine in boards/xxx/board.c
1371 is run early in the boot sequence.
1373 CONFIG_I2C_MULTI_BUS
1375 This option allows the use of multiple I2C buses, each of which
1376 must have a controller. At any point in time, only one bus is
1377 active. To switch to a different bus, use the 'i2c dev' command.
1378 Note that bus numbering is zero-based.
1380 CONFIG_SYS_I2C_NOPROBES
1382 This option specifies a list of I2C devices that will be skipped
1383 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1384 is set, specify a list of bus-device pairs. Otherwise, specify
1385 a 1D array of device addresses
1388 #undef CONFIG_I2C_MULTI_BUS
1389 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1391 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1393 #define CONFIG_I2C_MULTI_BUS
1394 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1396 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1398 CONFIG_SYS_SPD_BUS_NUM
1400 If defined, then this indicates the I2C bus number for DDR SPD.
1401 If not defined, then U-Boot assumes that SPD is on I2C bus 0.
1403 CONFIG_SYS_RTC_BUS_NUM
1405 If defined, then this indicates the I2C bus number for the RTC.
1406 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1408 CONFIG_SOFT_I2C_READ_REPEATED_START
1410 defining this will force the i2c_read() function in
1411 the soft_i2c driver to perform an I2C repeated start
1412 between writing the address pointer and reading the
1413 data. If this define is omitted the default behaviour
1414 of doing a stop-start sequence will be used. Most I2C
1415 devices can use either method, but some require one or
1418 - SPI Support: CONFIG_SPI
1420 Enables SPI driver (so far only tested with
1421 SPI EEPROM, also an instance works with Crystal A/D and
1422 D/As on the SACSng board)
1424 CONFIG_SYS_SPI_MXC_WAIT
1425 Timeout for waiting until spi transfer completed.
1426 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1428 - FPGA Support: CONFIG_FPGA
1430 Enables FPGA subsystem.
1432 CONFIG_FPGA_<vendor>
1434 Enables support for specific chip vendors.
1437 CONFIG_FPGA_<family>
1439 Enables support for FPGA family.
1440 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1444 Specify the number of FPGA devices to support.
1446 CONFIG_SYS_FPGA_PROG_FEEDBACK
1448 Enable printing of hash marks during FPGA configuration.
1450 CONFIG_SYS_FPGA_CHECK_BUSY
1452 Enable checks on FPGA configuration interface busy
1453 status by the configuration function. This option
1454 will require a board or device specific function to
1459 If defined, a function that provides delays in the FPGA
1460 configuration driver.
1462 CONFIG_SYS_FPGA_CHECK_CTRLC
1463 Allow Control-C to interrupt FPGA configuration
1465 CONFIG_SYS_FPGA_CHECK_ERROR
1467 Check for configuration errors during FPGA bitfile
1468 loading. For example, abort during Virtex II
1469 configuration if the INIT_B line goes low (which
1470 indicated a CRC error).
1472 CONFIG_SYS_FPGA_WAIT_INIT
1474 Maximum time to wait for the INIT_B line to de-assert
1475 after PROB_B has been de-asserted during a Virtex II
1476 FPGA configuration sequence. The default time is 500
1479 CONFIG_SYS_FPGA_WAIT_BUSY
1481 Maximum time to wait for BUSY to de-assert during
1482 Virtex II FPGA configuration. The default is 5 ms.
1484 CONFIG_SYS_FPGA_WAIT_CONFIG
1486 Time to wait after FPGA configuration. The default is
1489 - Vendor Parameter Protection:
1491 U-Boot considers the values of the environment
1492 variables "serial#" (Board Serial Number) and
1493 "ethaddr" (Ethernet Address) to be parameters that
1494 are set once by the board vendor / manufacturer, and
1495 protects these variables from casual modification by
1496 the user. Once set, these variables are read-only,
1497 and write or delete attempts are rejected. You can
1498 change this behaviour:
1500 If CONFIG_ENV_OVERWRITE is #defined in your config
1501 file, the write protection for vendor parameters is
1502 completely disabled. Anybody can change or delete
1505 Alternatively, if you define _both_ an ethaddr in the
1506 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1507 Ethernet address is installed in the environment,
1508 which can be changed exactly ONCE by the user. [The
1509 serial# is unaffected by this, i. e. it remains
1512 The same can be accomplished in a more flexible way
1513 for any variable by configuring the type of access
1514 to allow for those variables in the ".flags" variable
1515 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1520 Define this variable to enable the reservation of
1521 "protected RAM", i. e. RAM which is not overwritten
1522 by U-Boot. Define CONFIG_PRAM to hold the number of
1523 kB you want to reserve for pRAM. You can overwrite
1524 this default value by defining an environment
1525 variable "pram" to the number of kB you want to
1526 reserve. Note that the board info structure will
1527 still show the full amount of RAM. If pRAM is
1528 reserved, a new environment variable "mem" will
1529 automatically be defined to hold the amount of
1530 remaining RAM in a form that can be passed as boot
1531 argument to Linux, for instance like that:
1533 setenv bootargs ... mem=\${mem}
1536 This way you can tell Linux not to use this memory,
1537 either, which results in a memory region that will
1538 not be affected by reboots.
1540 *WARNING* If your board configuration uses automatic
1541 detection of the RAM size, you must make sure that
1542 this memory test is non-destructive. So far, the
1543 following board configurations are known to be
1546 IVMS8, IVML24, SPD8xx,
1547 HERMES, IP860, RPXlite, LWMON,
1553 In the current implementation, the local variables
1554 space and global environment variables space are
1555 separated. Local variables are those you define by
1556 simply typing `name=value'. To access a local
1557 variable later on, you have write `$name' or
1558 `${name}'; to execute the contents of a variable
1559 directly type `$name' at the command prompt.
1561 Global environment variables are those you use
1562 setenv/printenv to work with. To run a command stored
1563 in such a variable, you need to use the run command,
1564 and you must not use the '$' sign to access them.
1566 To store commands and special characters in a
1567 variable, please use double quotation marks
1568 surrounding the whole text of the variable, instead
1569 of the backslashes before semicolons and special
1572 - Command Line Editing and History:
1573 CONFIG_CMDLINE_PS_SUPPORT
1575 Enable support for changing the command prompt string
1576 at run-time. Only static string is supported so far.
1577 The string is obtained from environment variables PS1
1580 - Default Environment:
1581 CONFIG_EXTRA_ENV_SETTINGS
1583 Define this to contain any number of null terminated
1584 strings (variable = value pairs) that will be part of
1585 the default environment compiled into the boot image.
1587 For example, place something like this in your
1588 board's config file:
1590 #define CONFIG_EXTRA_ENV_SETTINGS \
1594 Warning: This method is based on knowledge about the
1595 internal format how the environment is stored by the
1596 U-Boot code. This is NOT an official, exported
1597 interface! Although it is unlikely that this format
1598 will change soon, there is no guarantee either.
1599 You better know what you are doing here.
1601 Note: overly (ab)use of the default environment is
1602 discouraged. Make sure to check other ways to preset
1603 the environment like the "source" command or the
1606 CONFIG_DELAY_ENVIRONMENT
1608 Normally the environment is loaded when the board is
1609 initialised so that it is available to U-Boot. This inhibits
1610 that so that the environment is not available until
1611 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1612 this is instead controlled by the value of
1613 /config/load-environment.
1615 - TFTP Fixed UDP Port:
1618 If this is defined, the environment variable tftpsrcp
1619 is used to supply the TFTP UDP source port value.
1620 If tftpsrcp isn't defined, the normal pseudo-random port
1621 number generator is used.
1623 Also, the environment variable tftpdstp is used to supply
1624 the TFTP UDP destination port value. If tftpdstp isn't
1625 defined, the normal port 69 is used.
1627 The purpose for tftpsrcp is to allow a TFTP server to
1628 blindly start the TFTP transfer using the pre-configured
1629 target IP address and UDP port. This has the effect of
1630 "punching through" the (Windows XP) firewall, allowing
1631 the remainder of the TFTP transfer to proceed normally.
1632 A better solution is to properly configure the firewall,
1633 but sometimes that is not allowed.
1635 CONFIG_STANDALONE_LOAD_ADDR
1637 This option defines a board specific value for the
1638 address where standalone program gets loaded, thus
1639 overwriting the architecture dependent default
1642 - Frame Buffer Address:
1645 Define CONFIG_FB_ADDR if you want to use specific
1646 address for frame buffer. This is typically the case
1647 when using a graphics controller has separate video
1648 memory. U-Boot will then place the frame buffer at
1649 the given address instead of dynamically reserving it
1650 in system RAM by calling lcd_setmem(), which grabs
1651 the memory for the frame buffer depending on the
1652 configured panel size.
1654 Please see board_init_f function.
1656 - Automatic software updates via TFTP server
1658 CONFIG_UPDATE_TFTP_CNT_MAX
1659 CONFIG_UPDATE_TFTP_MSEC_MAX
1661 These options enable and control the auto-update feature;
1662 for a more detailed description refer to doc/README.update.
1664 - MTD Support (mtdparts command, UBI support)
1665 CONFIG_MTD_UBI_WL_THRESHOLD
1666 This parameter defines the maximum difference between the highest
1667 erase counter value and the lowest erase counter value of eraseblocks
1668 of UBI devices. When this threshold is exceeded, UBI starts performing
1669 wear leveling by means of moving data from eraseblock with low erase
1670 counter to eraseblocks with high erase counter.
1672 The default value should be OK for SLC NAND flashes, NOR flashes and
1673 other flashes which have eraseblock life-cycle 100000 or more.
1674 However, in case of MLC NAND flashes which typically have eraseblock
1675 life-cycle less than 10000, the threshold should be lessened (e.g.,
1676 to 128 or 256, although it does not have to be power of 2).
1680 CONFIG_MTD_UBI_BEB_LIMIT
1681 This option specifies the maximum bad physical eraseblocks UBI
1682 expects on the MTD device (per 1024 eraseblocks). If the
1683 underlying flash does not admit of bad eraseblocks (e.g. NOR
1684 flash), this value is ignored.
1686 NAND datasheets often specify the minimum and maximum NVM
1687 (Number of Valid Blocks) for the flashes' endurance lifetime.
1688 The maximum expected bad eraseblocks per 1024 eraseblocks
1689 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1690 which gives 20 for most NANDs (MaxNVB is basically the total
1691 count of eraseblocks on the chip).
1693 To put it differently, if this value is 20, UBI will try to
1694 reserve about 1.9% of physical eraseblocks for bad blocks
1695 handling. And that will be 1.9% of eraseblocks on the entire
1696 NAND chip, not just the MTD partition UBI attaches. This means
1697 that if you have, say, a NAND flash chip admits maximum 40 bad
1698 eraseblocks, and it is split on two MTD partitions of the same
1699 size, UBI will reserve 40 eraseblocks when attaching a
1704 CONFIG_MTD_UBI_FASTMAP
1705 Fastmap is a mechanism which allows attaching an UBI device
1706 in nearly constant time. Instead of scanning the whole MTD device it
1707 only has to locate a checkpoint (called fastmap) on the device.
1708 The on-flash fastmap contains all information needed to attach
1709 the device. Using fastmap makes only sense on large devices where
1710 attaching by scanning takes long. UBI will not automatically install
1711 a fastmap on old images, but you can set the UBI parameter
1712 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1713 that fastmap-enabled images are still usable with UBI implementations
1714 without fastmap support. On typical flash devices the whole fastmap
1715 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1717 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1718 Set this parameter to enable fastmap automatically on images
1722 CONFIG_MTD_UBI_FM_DEBUG
1723 Enable UBI fastmap debug
1728 Enable building of SPL globally.
1730 CONFIG_SPL_MAX_FOOTPRINT
1731 Maximum size in memory allocated to the SPL, BSS included.
1732 When defined, the linker checks that the actual memory
1733 used by SPL from _start to __bss_end does not exceed it.
1734 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1735 must not be both defined at the same time.
1738 Maximum size of the SPL image (text, data, rodata, and
1739 linker lists sections), BSS excluded.
1740 When defined, the linker checks that the actual size does
1743 CONFIG_SPL_RELOC_TEXT_BASE
1744 Address to relocate to. If unspecified, this is equal to
1745 CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
1747 CONFIG_SPL_BSS_START_ADDR
1748 Link address for the BSS within the SPL binary.
1750 CONFIG_SPL_BSS_MAX_SIZE
1751 Maximum size in memory allocated to the SPL BSS.
1752 When defined, the linker checks that the actual memory used
1753 by SPL from __bss_start to __bss_end does not exceed it.
1754 CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
1755 must not be both defined at the same time.
1758 Adress of the start of the stack SPL will use
1760 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1761 When defined, SPL will panic() if the image it has
1762 loaded does not have a signature.
1763 Defining this is useful when code which loads images
1764 in SPL cannot guarantee that absolutely all read errors
1766 An example is the LPC32XX MLC NAND driver, which will
1767 consider that a completely unreadable NAND block is bad,
1768 and thus should be skipped silently.
1770 CONFIG_SPL_RELOC_STACK
1771 Adress of the start of the stack SPL will use after
1772 relocation. If unspecified, this is equal to
1775 CONFIG_SYS_SPL_MALLOC_START
1776 Starting address of the malloc pool used in SPL.
1777 When this option is set the full malloc is used in SPL and
1778 it is set up by spl_init() and before that, the simple malloc()
1779 can be used if CONFIG_SYS_MALLOC_F is defined.
1781 CONFIG_SYS_SPL_MALLOC_SIZE
1782 The size of the malloc pool used in SPL.
1784 CONFIG_SPL_DISPLAY_PRINT
1785 For ARM, enable an optional function to print more information
1786 about the running system.
1788 CONFIG_SPL_INIT_MINIMAL
1789 Arch init code should be built for a very small image
1791 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
1792 CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
1793 Sector and number of sectors to load kernel argument
1794 parameters from when MMC is being used in raw mode
1797 CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
1798 Filename to read to load U-Boot when reading from filesystem
1800 CONFIG_SPL_FS_LOAD_KERNEL_NAME
1801 Filename to read to load kernel uImage when reading
1802 from filesystem (for Falcon mode)
1804 CONFIG_SPL_FS_LOAD_ARGS_NAME
1805 Filename to read to load kernel argument parameters
1806 when reading from filesystem (for Falcon mode)
1808 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1809 Set this for NAND SPL on PPC mpc83xx targets, so that
1810 start.S waits for the rest of the SPL to load before
1811 continuing (the hardware starts execution after just
1812 loading the first page rather than the full 4K).
1814 CONFIG_SPL_SKIP_RELOCATE
1815 Avoid SPL relocation
1818 Support for a lightweight UBI (fastmap) scanner and
1821 CONFIG_SPL_NAND_RAW_ONLY
1822 Support to boot only raw u-boot.bin images. Use this only
1823 if you need to save space.
1825 CONFIG_SPL_COMMON_INIT_DDR
1826 Set for common ddr init with serial presence detect in
1829 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1830 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1831 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1832 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1833 CONFIG_SYS_NAND_ECCBYTES
1834 Defines the size and behavior of the NAND that SPL uses
1837 CONFIG_SYS_NAND_U_BOOT_DST
1838 Location in memory to load U-Boot to
1840 CONFIG_SYS_NAND_U_BOOT_SIZE
1841 Size of image to load
1843 CONFIG_SYS_NAND_U_BOOT_START
1844 Entry point in loaded image to jump to
1846 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1847 Define this if you need to first read the OOB and then the
1848 data. This is used, for example, on davinci platforms.
1850 CONFIG_SPL_RAM_DEVICE
1851 Support for running image already present in ram, in SPL binary
1854 Image offset to which the SPL should be padded before appending
1855 the SPL payload. By default, this is defined as
1856 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1857 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1858 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1861 Final target image containing SPL and payload. Some SPLs
1862 use an arch-specific makefile fragment instead, for
1863 example if more than one image needs to be produced.
1865 CONFIG_SPL_FIT_PRINT
1866 Printing information about a FIT image adds quite a bit of
1867 code to SPL. So this is normally disabled in SPL. Use this
1868 option to re-enable it. This will affect the output of the
1869 bootm command when booting a FIT image.
1873 Enable building of TPL globally.
1876 Image offset to which the TPL should be padded before appending
1877 the TPL payload. By default, this is defined as
1878 CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
1879 CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
1880 payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
1882 - Interrupt support (PPC):
1884 There are common interrupt_init() and timer_interrupt()
1885 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1886 for CPU specific initialization. interrupt_init_cpu()
1887 should set decrementer_count to appropriate value. If
1888 CPU resets decrementer automatically after interrupt
1889 (ppc4xx) it should set decrementer_count to zero.
1890 timer_interrupt() calls timer_interrupt_cpu() for CPU
1891 specific handling. If board has watchdog / status_led
1892 / other_activity_monitor it works automatically from
1893 general timer_interrupt().
1896 Board initialization settings:
1897 ------------------------------
1899 During Initialization u-boot calls a number of board specific functions
1900 to allow the preparation of board specific prerequisites, e.g. pin setup
1901 before drivers are initialized. To enable these callbacks the
1902 following configuration macros have to be defined. Currently this is
1903 architecture specific, so please check arch/your_architecture/lib/board.c
1904 typically in board_init_f() and board_init_r().
1906 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1907 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1908 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1910 Configuration Settings:
1911 -----------------------
1913 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1914 Optionally it can be defined to support 64-bit memory commands.
1916 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1917 undefine this when you're short of memory.
1919 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1920 width of the commands listed in the 'help' command output.
1922 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1923 prompt for user input.
1925 - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
1927 - CONFIG_SYS_PBSIZE: Buffer size for Console output
1929 - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
1931 - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
1932 the application (usually a Linux kernel) when it is
1935 - CONFIG_SYS_BAUDRATE_TABLE:
1936 List of legal baudrate settings for this board.
1938 - CONFIG_SYS_MEM_RESERVE_SECURE
1939 Only implemented for ARMv8 for now.
1940 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1941 is substracted from total RAM and won't be reported to OS.
1942 This memory can be used as secure memory. A variable
1943 gd->arch.secure_ram is used to track the location. In systems
1944 the RAM base is not zero, or RAM is divided into banks,
1945 this variable needs to be recalcuated to get the address.
1947 - CONFIG_SYS_MEM_TOP_HIDE:
1948 If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
1949 this specified memory area will get subtracted from the top
1950 (end) of RAM and won't get "touched" at all by U-Boot. By
1951 fixing up gd->ram_size the Linux kernel should gets passed
1952 the now "corrected" memory size and won't touch it either.
1953 This should work for arch/ppc and arch/powerpc. Only Linux
1954 board ports in arch/powerpc with bootwrapper support that
1955 recalculate the memory size from the SDRAM controller setup
1956 will have to get fixed in Linux additionally.
1958 This option can be used as a workaround for the 440EPx/GRx
1959 CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
1962 WARNING: Please make sure that this value is a multiple of
1963 the Linux page size (normally 4k). If this is not the case,
1964 then the end address of the Linux memory will be located at a
1965 non page size aligned address and this could cause major
1968 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1969 Enable temporary baudrate change while serial download
1971 - CONFIG_SYS_SDRAM_BASE:
1972 Physical start address of SDRAM. _Must_ be 0 here.
1974 - CONFIG_SYS_FLASH_BASE:
1975 Physical start address of Flash memory.
1977 - CONFIG_SYS_MONITOR_BASE:
1978 Physical start address of boot monitor code (set by
1979 make config files to be same as the text base address
1980 (CONFIG_SYS_TEXT_BASE) used when linking) - same as
1981 CONFIG_SYS_FLASH_BASE when booting from flash.
1983 - CONFIG_SYS_MONITOR_LEN:
1984 Size of memory reserved for monitor code, used to
1985 determine _at_compile_time_ (!) if the environment is
1986 embedded within the U-Boot image, or in a separate
1989 - CONFIG_SYS_MALLOC_LEN:
1990 Size of DRAM reserved for malloc() use.
1992 - CONFIG_SYS_MALLOC_F_LEN
1993 Size of the malloc() pool for use before relocation. If
1994 this is defined, then a very simple malloc() implementation
1995 will become available before relocation. The address is just
1996 below the global data, and the stack is moved down to make
1999 This feature allocates regions with increasing addresses
2000 within the region. calloc() is supported, but realloc()
2001 is not available. free() is supported but does nothing.
2002 The memory will be freed (or in fact just forgotten) when
2003 U-Boot relocates itself.
2005 - CONFIG_SYS_MALLOC_SIMPLE
2006 Provides a simple and small malloc() and calloc() for those
2007 boards which do not use the full malloc in SPL (which is
2008 enabled with CONFIG_SYS_SPL_MALLOC_START).
2010 - CONFIG_SYS_NONCACHED_MEMORY:
2011 Size of non-cached memory area. This area of memory will be
2012 typically located right below the malloc() area and mapped
2013 uncached in the MMU. This is useful for drivers that would
2014 otherwise require a lot of explicit cache maintenance. For
2015 some drivers it's also impossible to properly maintain the
2016 cache. For example if the regions that need to be flushed
2017 are not a multiple of the cache-line size, *and* padding
2018 cannot be allocated between the regions to align them (i.e.
2019 if the HW requires a contiguous array of regions, and the
2020 size of each region is not cache-aligned), then a flush of
2021 one region may result in overwriting data that hardware has
2022 written to another region in the same cache-line. This can
2023 happen for example in network drivers where descriptors for
2024 buffers are typically smaller than the CPU cache-line (e.g.
2025 16 bytes vs. 32 or 64 bytes).
2027 Non-cached memory is only supported on 32-bit ARM at present.
2029 - CONFIG_SYS_BOOTM_LEN:
2030 Normally compressed uImages are limited to an
2031 uncompressed size of 8 MBytes. If this is not enough,
2032 you can define CONFIG_SYS_BOOTM_LEN in your board config file
2033 to adjust this setting to your needs.
2035 - CONFIG_SYS_BOOTMAPSZ:
2036 Maximum size of memory mapped by the startup code of
2037 the Linux kernel; all data that must be processed by
2038 the Linux kernel (bd_info, boot arguments, FDT blob if
2039 used) must be put below this limit, unless "bootm_low"
2040 environment variable is defined and non-zero. In such case
2041 all data for the Linux kernel must be between "bootm_low"
2042 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
2043 variable "bootm_mapsize" will override the value of
2044 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
2045 then the value in "bootm_size" will be used instead.
2047 - CONFIG_SYS_BOOT_RAMDISK_HIGH:
2048 Enable initrd_high functionality. If defined then the
2049 initrd_high feature is enabled and the bootm ramdisk subcommand
2052 - CONFIG_SYS_BOOT_GET_CMDLINE:
2053 Enables allocating and saving kernel cmdline in space between
2054 "bootm_low" and "bootm_low" + BOOTMAPSZ.
2056 - CONFIG_SYS_BOOT_GET_KBD:
2057 Enables allocating and saving a kernel copy of the bd_info in
2058 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
2060 - CONFIG_SYS_MAX_FLASH_SECT:
2061 Max number of sectors on a Flash chip
2063 - CONFIG_SYS_FLASH_ERASE_TOUT:
2064 Timeout for Flash erase operations (in ms)
2066 - CONFIG_SYS_FLASH_WRITE_TOUT:
2067 Timeout for Flash write operations (in ms)
2069 - CONFIG_SYS_FLASH_LOCK_TOUT
2070 Timeout for Flash set sector lock bit operation (in ms)
2072 - CONFIG_SYS_FLASH_UNLOCK_TOUT
2073 Timeout for Flash clear lock bits operation (in ms)
2075 - CONFIG_SYS_FLASH_PROTECTION
2076 If defined, hardware flash sectors protection is used
2077 instead of U-Boot software protection.
2079 - CONFIG_SYS_DIRECT_FLASH_TFTP:
2081 Enable TFTP transfers directly to flash memory;
2082 without this option such a download has to be
2083 performed in two steps: (1) download to RAM, and (2)
2084 copy from RAM to flash.
2086 The two-step approach is usually more reliable, since
2087 you can check if the download worked before you erase
2088 the flash, but in some situations (when system RAM is
2089 too limited to allow for a temporary copy of the
2090 downloaded image) this option may be very useful.
2092 - CONFIG_SYS_FLASH_CFI:
2093 Define if the flash driver uses extra elements in the
2094 common flash structure for storing flash geometry.
2096 - CONFIG_FLASH_CFI_DRIVER
2097 This option also enables the building of the cfi_flash driver
2098 in the drivers directory
2100 - CONFIG_FLASH_CFI_MTD
2101 This option enables the building of the cfi_mtd driver
2102 in the drivers directory. The driver exports CFI flash
2105 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
2106 Use buffered writes to flash.
2108 - CONFIG_FLASH_SPANSION_S29WS_N
2109 s29ws-n MirrorBit flash has non-standard addresses for buffered
2112 - CONFIG_SYS_FLASH_QUIET_TEST
2113 If this option is defined, the common CFI flash doesn't
2114 print it's warning upon not recognized FLASH banks. This
2115 is useful, if some of the configured banks are only
2116 optionally available.
2118 - CONFIG_FLASH_SHOW_PROGRESS
2119 If defined (must be an integer), print out countdown
2120 digits and dots. Recommended value: 45 (9..1) for 80
2121 column displays, 15 (3..1) for 40 column displays.
2123 - CONFIG_FLASH_VERIFY
2124 If defined, the content of the flash (destination) is compared
2125 against the source after the write operation. An error message
2126 will be printed when the contents are not identical.
2127 Please note that this option is useless in nearly all cases,
2128 since such flash programming errors usually are detected earlier
2129 while unprotecting/erasing/programming. Please only enable
2130 this option if you really know what you are doing.
2132 - CONFIG_SYS_RX_ETH_BUFFER:
2133 Defines the number of Ethernet receive buffers. On some
2134 Ethernet controllers it is recommended to set this value
2135 to 8 or even higher (EEPRO100 or 405 EMAC), since all
2136 buffers can be full shortly after enabling the interface
2137 on high Ethernet traffic.
2138 Defaults to 4 if not defined.
2140 - CONFIG_ENV_MAX_ENTRIES
2142 Maximum number of entries in the hash table that is used
2143 internally to store the environment settings. The default
2144 setting is supposed to be generous and should work in most
2145 cases. This setting can be used to tune behaviour; see
2146 lib/hashtable.c for details.
2148 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2149 - CONFIG_ENV_FLAGS_LIST_STATIC
2150 Enable validation of the values given to environment variables when
2151 calling env set. Variables can be restricted to only decimal,
2152 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
2153 the variables can also be restricted to IP address or MAC address.
2155 The format of the list is:
2156 type_attribute = [s|d|x|b|i|m]
2157 access_attribute = [a|r|o|c]
2158 attributes = type_attribute[access_attribute]
2159 entry = variable_name[:attributes]
2162 The type attributes are:
2163 s - String (default)
2166 b - Boolean ([1yYtT|0nNfF])
2170 The access attributes are:
2176 - CONFIG_ENV_FLAGS_LIST_DEFAULT
2177 Define this to a list (string) to define the ".flags"
2178 environment variable in the default or embedded environment.
2180 - CONFIG_ENV_FLAGS_LIST_STATIC
2181 Define this to a list (string) to define validation that
2182 should be done if an entry is not found in the ".flags"
2183 environment variable. To override a setting in the static
2184 list, simply add an entry for the same variable name to the
2187 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
2188 regular expression. This allows multiple variables to define the same
2189 flags without explicitly listing them for each variable.
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_BUILD_ENVCRC:
2197 Builds up envcrc with the target environment so that external utils
2198 may easily extract it and embed it in final U-Boot images.
2200 BE CAREFUL! The first access to the environment happens quite early
2201 in U-Boot initialization (when we try to get the setting of for the
2202 console baudrate). You *MUST* have mapped your NVRAM area then, or
2205 Please note that even with NVRAM we still use a copy of the
2206 environment in RAM: we could work on NVRAM directly, but we want to
2207 keep settings there always unmodified except somebody uses "saveenv"
2208 to save the current settings.
2210 BE CAREFUL! For some special cases, the local device can not use
2211 "saveenv" command. For example, the local device will get the
2212 environment stored in a remote NOR flash by SRIO or PCIE link,
2213 but it can not erase, write this NOR flash by SRIO or PCIE interface.
2215 - CONFIG_NAND_ENV_DST
2217 Defines address in RAM to which the nand_spl code should copy the
2218 environment. If redundant environment is used, it will be copied to
2219 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
2221 Please note that the environment is read-only until the monitor
2222 has been relocated to RAM and a RAM copy of the environment has been
2223 created; also, when using EEPROM you will have to use env_get_f()
2224 until then to read environment variables.
2226 The environment is protected by a CRC32 checksum. Before the monitor
2227 is relocated into RAM, as a result of a bad CRC you will be working
2228 with the compiled-in default environment - *silently*!!! [This is
2229 necessary, because the first environment variable we need is the
2230 "baudrate" setting for the console - if we have a bad CRC, we don't
2231 have any device yet where we could complain.]
2233 Note: once the monitor has been relocated, then it will complain if
2234 the default environment is used; a new CRC is computed as soon as you
2235 use the "saveenv" command to store a valid environment.
2237 - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
2238 Echo the inverted Ethernet link state to the fault LED.
2240 Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
2241 also needs to be defined.
2243 - CONFIG_SYS_FAULT_MII_ADDR:
2244 MII address of the PHY to check for the Ethernet link state.
2246 - CONFIG_NS16550_MIN_FUNCTIONS:
2247 Define this if you desire to only have use of the NS16550_init
2248 and NS16550_putc functions for the serial driver located at
2249 drivers/serial/ns16550.c. This option is useful for saving
2250 space for already greatly restricted images, including but not
2251 limited to NAND_SPL configurations.
2253 - CONFIG_DISPLAY_BOARDINFO
2254 Display information about the board that U-Boot is running on
2255 when U-Boot starts up. The board function checkboard() is called
2258 - CONFIG_DISPLAY_BOARDINFO_LATE
2259 Similar to the previous option, but display this information
2260 later, once stdio is running and output goes to the LCD, if
2263 - CONFIG_BOARD_SIZE_LIMIT:
2264 Maximum size of the U-Boot image. When defined, the
2265 build system checks that the actual size does not
2268 Low Level (hardware related) configuration options:
2269 ---------------------------------------------------
2271 - CONFIG_SYS_CACHELINE_SIZE:
2272 Cache Line Size of the CPU.
2274 - CONFIG_SYS_CCSRBAR_DEFAULT:
2275 Default (power-on reset) physical address of CCSR on Freescale
2278 - CONFIG_SYS_CCSRBAR:
2279 Virtual address of CCSR. On a 32-bit build, this is typically
2280 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
2282 - CONFIG_SYS_CCSRBAR_PHYS:
2283 Physical address of CCSR. CCSR can be relocated to a new
2284 physical address, if desired. In this case, this macro should
2285 be set to that address. Otherwise, it should be set to the
2286 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
2287 is typically relocated on 36-bit builds. It is recommended
2288 that this macro be defined via the _HIGH and _LOW macros:
2290 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
2291 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
2293 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
2294 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
2295 either 0 (32-bit build) or 0xF (36-bit build). This macro is
2296 used in assembly code, so it must not contain typecasts or
2297 integer size suffixes (e.g. "ULL").
2299 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
2300 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
2301 used in assembly code, so it must not contain typecasts or
2302 integer size suffixes (e.g. "ULL").
2304 - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
2305 If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
2306 forced to a value that ensures that CCSR is not relocated.
2308 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
2309 DO NOT CHANGE unless you know exactly what you're
2310 doing! (11-4) [MPC8xx systems only]
2312 - CONFIG_SYS_INIT_RAM_ADDR:
2314 Start address of memory area that can be used for
2315 initial data and stack; please note that this must be
2316 writable memory that is working WITHOUT special
2317 initialization, i. e. you CANNOT use normal RAM which
2318 will become available only after programming the
2319 memory controller and running certain initialization
2322 U-Boot uses the following memory types:
2323 - MPC8xx: IMMR (internal memory of the CPU)
2325 - CONFIG_SYS_GBL_DATA_OFFSET:
2327 Offset of the initial data structure in the memory
2328 area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
2329 CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
2330 data is located at the end of the available space
2331 (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
2332 GENERATED_GBL_DATA_SIZE), and the initial stack is just
2333 below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
2334 CONFIG_SYS_GBL_DATA_OFFSET) downward.
2337 On the MPC824X (or other systems that use the data
2338 cache for initial memory) the address chosen for
2339 CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
2340 point to an otherwise UNUSED address space between
2341 the top of RAM and the start of the PCI space.
2343 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
2345 - CONFIG_SYS_OR_TIMING_SDRAM:
2348 - CONFIG_SYS_MAMR_PTA:
2349 periodic timer for refresh
2352 Chip has SRIO or not
2355 Board has SRIO 1 port available
2358 Board has SRIO 2 port available
2360 - CONFIG_SRIO_PCIE_BOOT_MASTER
2361 Board can support master function for Boot from SRIO and PCIE
2363 - CONFIG_SYS_SRIOn_MEM_VIRT:
2364 Virtual Address of SRIO port 'n' memory region
2366 - CONFIG_SYS_SRIOn_MEM_PHYxS:
2367 Physical Address of SRIO port 'n' memory region
2369 - CONFIG_SYS_SRIOn_MEM_SIZE:
2370 Size of SRIO port 'n' memory region
2372 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
2373 Defined to tell the NAND controller that the NAND chip is using
2375 Not all NAND drivers use this symbol.
2376 Example of drivers that use it:
2377 - drivers/mtd/nand/raw/ndfc.c
2378 - drivers/mtd/nand/raw/mxc_nand.c
2380 - CONFIG_SYS_NDFC_EBC0_CFG
2381 Sets the EBC0_CFG register for the NDFC. If not defined
2382 a default value will be used.
2385 Get DDR timing information from an I2C EEPROM. Common
2386 with pluggable memory modules such as SODIMMs
2389 I2C address of the SPD EEPROM
2391 - CONFIG_SYS_SPD_BUS_NUM
2392 If SPD EEPROM is on an I2C bus other than the first
2393 one, specify here. Note that the value must resolve
2394 to something your driver can deal with.
2396 - CONFIG_SYS_DDR_RAW_TIMING
2397 Get DDR timing information from other than SPD. Common with
2398 soldered DDR chips onboard without SPD. DDR raw timing
2399 parameters are extracted from datasheet and hard-coded into
2400 header files or board specific files.
2402 - CONFIG_FSL_DDR_INTERACTIVE
2403 Enable interactive DDR debugging. See doc/README.fsl-ddr.
2405 - CONFIG_FSL_DDR_SYNC_REFRESH
2406 Enable sync of refresh for multiple controllers.
2408 - CONFIG_FSL_DDR_BIST
2409 Enable built-in memory test for Freescale DDR controllers.
2411 - CONFIG_SYS_83XX_DDR_USES_CS0
2412 Only for 83xx systems. If specified, then DDR should
2413 be configured using CS0 and CS1 instead of CS2 and CS3.
2416 Enable RMII mode for all FECs.
2417 Note that this is a global option, we can't
2418 have one FEC in standard MII mode and another in RMII mode.
2420 - CONFIG_CRC32_VERIFY
2421 Add a verify option to the crc32 command.
2424 => crc32 -v <address> <count> <crc32>
2426 Where address/count indicate a memory area
2427 and crc32 is the correct crc32 which the
2431 Add the "loopw" memory command. This only takes effect if
2432 the memory commands are activated globally (CONFIG_CMD_MEMORY).
2434 - CONFIG_CMD_MX_CYCLIC
2435 Add the "mdc" and "mwc" memory commands. These are cyclic
2440 This command will print 4 bytes (10,11,12,13) each 500 ms.
2442 => mwc.l 100 12345678 10
2443 This command will write 12345678 to address 100 all 10 ms.
2445 This only takes effect if the memory commands are activated
2446 globally (CONFIG_CMD_MEMORY).
2449 Set when the currently-running compilation is for an artifact
2450 that will end up in the SPL (as opposed to the TPL or U-Boot
2451 proper). Code that needs stage-specific behavior should check
2455 Set when the currently-running compilation is for an artifact
2456 that will end up in the TPL (as opposed to the SPL or U-Boot
2457 proper). Code that needs stage-specific behavior should check
2460 - CONFIG_SYS_MPC85XX_NO_RESETVEC
2461 Only for 85xx systems. If this variable is specified, the section
2462 .resetvec is not kept and the section .bootpg is placed in the
2463 previous 4k of the .text section.
2465 - CONFIG_ARCH_MAP_SYSMEM
2466 Generally U-Boot (and in particular the md command) uses
2467 effective address. It is therefore not necessary to regard
2468 U-Boot address as virtual addresses that need to be translated
2469 to physical addresses. However, sandbox requires this, since
2470 it maintains its own little RAM buffer which contains all
2471 addressable memory. This option causes some memory accesses
2472 to be mapped through map_sysmem() / unmap_sysmem().
2474 - CONFIG_X86_RESET_VECTOR
2475 If defined, the x86 reset vector code is included. This is not
2476 needed when U-Boot is running from Coreboot.
2478 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
2479 Option to disable subpage write in NAND driver
2480 driver that uses this:
2481 drivers/mtd/nand/raw/davinci_nand.c
2483 Freescale QE/FMAN Firmware Support:
2484 -----------------------------------
2486 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
2487 loading of "firmware", which is encoded in the QE firmware binary format.
2488 This firmware often needs to be loaded during U-Boot booting, so macros
2489 are used to identify the storage device (NOR flash, SPI, etc) and the address
2492 - CONFIG_SYS_FMAN_FW_ADDR
2493 The address in the storage device where the FMAN microcode is located. The
2494 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2497 - CONFIG_SYS_QE_FW_ADDR
2498 The address in the storage device where the QE microcode is located. The
2499 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
2502 - CONFIG_SYS_QE_FMAN_FW_LENGTH
2503 The maximum possible size of the firmware. The firmware binary format
2504 has a field that specifies the actual size of the firmware, but it
2505 might not be possible to read any part of the firmware unless some
2506 local storage is allocated to hold the entire firmware first.
2508 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2509 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2510 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2511 virtual address in NOR flash.
2513 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2514 Specifies that QE/FMAN firmware is located in NAND flash.
2515 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2517 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2518 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2519 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2521 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2522 Specifies that QE/FMAN firmware is located in the remote (master)
2523 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2524 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2525 window->master inbound window->master LAW->the ucode address in
2526 master's memory space.
2528 Freescale Layerscape Management Complex Firmware Support:
2529 ---------------------------------------------------------
2530 The Freescale Layerscape Management Complex (MC) supports the loading of
2532 This firmware often needs to be loaded during U-Boot booting, so macros
2533 are used to identify the storage device (NOR flash, SPI, etc) and the address
2536 - CONFIG_FSL_MC_ENET
2537 Enable the MC driver for Layerscape SoCs.
2539 Freescale Layerscape Debug Server Support:
2540 -------------------------------------------
2541 The Freescale Layerscape Debug Server Support supports the loading of
2542 "Debug Server firmware" and triggering SP boot-rom.
2543 This firmware often needs to be loaded during U-Boot booting.
2545 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2546 Define alignment of reserved memory MC requires
2551 In order to achieve reproducible builds, timestamps used in the U-Boot build
2552 process have to be set to a fixed value.
2554 This is done using the SOURCE_DATE_EPOCH environment variable.
2555 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2556 option for U-Boot or an environment variable in U-Boot.
2558 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2560 Building the Software:
2561 ======================
2563 Building U-Boot has been tested in several native build environments
2564 and in many different cross environments. Of course we cannot support
2565 all possibly existing versions of cross development tools in all
2566 (potentially obsolete) versions. In case of tool chain problems we
2567 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2568 which is extensively used to build and test U-Boot.
2570 If you are not using a native environment, it is assumed that you
2571 have GNU cross compiling tools available in your path. In this case,
2572 you must set the environment variable CROSS_COMPILE in your shell.
2573 Note that no changes to the Makefile or any other source files are
2574 necessary. For example using the ELDK on a 4xx CPU, please enter:
2576 $ CROSS_COMPILE=ppc_4xx-
2577 $ export CROSS_COMPILE
2579 U-Boot is intended to be simple to build. After installing the
2580 sources you must configure U-Boot for one specific board type. This
2585 where "NAME_defconfig" is the name of one of the existing configu-
2586 rations; see configs/*_defconfig for supported names.
2588 Note: for some boards special configuration names may exist; check if
2589 additional information is available from the board vendor; for
2590 instance, the TQM823L systems are available without (standard)
2591 or with LCD support. You can select such additional "features"
2592 when choosing the configuration, i. e.
2594 make TQM823L_defconfig
2595 - will configure for a plain TQM823L, i. e. no LCD support
2597 make TQM823L_LCD_defconfig
2598 - will configure for a TQM823L with U-Boot console on LCD
2603 Finally, type "make all", and you should get some working U-Boot
2604 images ready for download to / installation on your system:
2606 - "u-boot.bin" is a raw binary image
2607 - "u-boot" is an image in ELF binary format
2608 - "u-boot.srec" is in Motorola S-Record format
2610 By default the build is performed locally and the objects are saved
2611 in the source directory. One of the two methods can be used to change
2612 this behavior and build U-Boot to some external directory:
2614 1. Add O= to the make command line invocations:
2616 make O=/tmp/build distclean
2617 make O=/tmp/build NAME_defconfig
2618 make O=/tmp/build all
2620 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2622 export KBUILD_OUTPUT=/tmp/build
2627 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2630 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2631 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2632 For example to treat all compiler warnings as errors:
2634 make KCFLAGS=-Werror
2636 Please be aware that the Makefiles assume you are using GNU make, so
2637 for instance on NetBSD you might need to use "gmake" instead of
2641 If the system board that you have is not listed, then you will need
2642 to port U-Boot to your hardware platform. To do this, follow these
2645 1. Create a new directory to hold your board specific code. Add any
2646 files you need. In your board directory, you will need at least
2647 the "Makefile" and a "<board>.c".
2648 2. Create a new configuration file "include/configs/<board>.h" for
2650 3. If you're porting U-Boot to a new CPU, then also create a new
2651 directory to hold your CPU specific code. Add any files you need.
2652 4. Run "make <board>_defconfig" with your new name.
2653 5. Type "make", and you should get a working "u-boot.srec" file
2654 to be installed on your target system.
2655 6. Debug and solve any problems that might arise.
2656 [Of course, this last step is much harder than it sounds.]
2659 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2660 ==============================================================
2662 If you have modified U-Boot sources (for instance added a new board
2663 or support for new devices, a new CPU, etc.) you are expected to
2664 provide feedback to the other developers. The feedback normally takes
2665 the form of a "patch", i.e. a context diff against a certain (latest
2666 official or latest in the git repository) version of U-Boot sources.
2668 But before you submit such a patch, please verify that your modifi-
2669 cation did not break existing code. At least make sure that *ALL* of
2670 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2671 just run the buildman script (tools/buildman/buildman), which will
2672 configure and build U-Boot for ALL supported system. Be warned, this
2673 will take a while. Please see the buildman README, or run 'buildman -H'
2677 See also "U-Boot Porting Guide" below.
2680 Monitor Commands - Overview:
2681 ============================
2683 go - start application at address 'addr'
2684 run - run commands in an environment variable
2685 bootm - boot application image from memory
2686 bootp - boot image via network using BootP/TFTP protocol
2687 bootz - boot zImage from memory
2688 tftpboot- boot image via network using TFTP protocol
2689 and env variables "ipaddr" and "serverip"
2690 (and eventually "gatewayip")
2691 tftpput - upload a file via network using TFTP protocol
2692 rarpboot- boot image via network using RARP/TFTP protocol
2693 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2694 loads - load S-Record file over serial line
2695 loadb - load binary file over serial line (kermit mode)
2697 mm - memory modify (auto-incrementing)
2698 nm - memory modify (constant address)
2699 mw - memory write (fill)
2702 cmp - memory compare
2703 crc32 - checksum calculation
2704 i2c - I2C sub-system
2705 sspi - SPI utility commands
2706 base - print or set address offset
2707 printenv- print environment variables
2708 pwm - control pwm channels
2709 setenv - set environment variables
2710 saveenv - save environment variables to persistent storage
2711 protect - enable or disable FLASH write protection
2712 erase - erase FLASH memory
2713 flinfo - print FLASH memory information
2714 nand - NAND memory operations (see doc/README.nand)
2715 bdinfo - print Board Info structure
2716 iminfo - print header information for application image
2717 coninfo - print console devices and informations
2718 ide - IDE sub-system
2719 loop - infinite loop on address range
2720 loopw - infinite write loop on address range
2721 mtest - simple RAM test
2722 icache - enable or disable instruction cache
2723 dcache - enable or disable data cache
2724 reset - Perform RESET of the CPU
2725 echo - echo args to console
2726 version - print monitor version
2727 help - print online help
2728 ? - alias for 'help'
2731 Monitor Commands - Detailed Description:
2732 ========================================
2736 For now: just type "help <command>".
2739 Note for Redundant Ethernet Interfaces:
2740 =======================================
2742 Some boards come with redundant Ethernet interfaces; U-Boot supports
2743 such configurations and is capable of automatic selection of a
2744 "working" interface when needed. MAC assignment works as follows:
2746 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2747 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2748 "eth1addr" (=>eth1), "eth2addr", ...
2750 If the network interface stores some valid MAC address (for instance
2751 in SROM), this is used as default address if there is NO correspon-
2752 ding setting in the environment; if the corresponding environment
2753 variable is set, this overrides the settings in the card; that means:
2755 o If the SROM has a valid MAC address, and there is no address in the
2756 environment, the SROM's address is used.
2758 o If there is no valid address in the SROM, and a definition in the
2759 environment exists, then the value from the environment variable is
2762 o If both the SROM and the environment contain a MAC address, and
2763 both addresses are the same, this MAC address is used.
2765 o If both the SROM and the environment contain a MAC address, and the
2766 addresses differ, the value from the environment is used and a
2769 o If neither SROM nor the environment contain a MAC address, an error
2770 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2771 a random, locally-assigned MAC is used.
2773 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2774 will be programmed into hardware as part of the initialization process. This
2775 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2776 The naming convention is as follows:
2777 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2782 U-Boot is capable of booting (and performing other auxiliary operations on)
2783 images in two formats:
2785 New uImage format (FIT)
2786 -----------------------
2788 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2789 to Flattened Device Tree). It allows the use of images with multiple
2790 components (several kernels, ramdisks, etc.), with contents protected by
2791 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2797 Old image format is based on binary files which can be basically anything,
2798 preceded by a special header; see the definitions in include/image.h for
2799 details; basically, the header defines the following image properties:
2801 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2802 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2803 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2804 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2805 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2806 IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2807 Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
2808 * Compression Type (uncompressed, gzip, bzip2)
2814 The header is marked by a special Magic Number, and both the header
2815 and the data portions of the image are secured against corruption by
2822 Although U-Boot should support any OS or standalone application
2823 easily, the main focus has always been on Linux during the design of
2826 U-Boot includes many features that so far have been part of some
2827 special "boot loader" code within the Linux kernel. Also, any
2828 "initrd" images to be used are no longer part of one big Linux image;
2829 instead, kernel and "initrd" are separate images. This implementation
2830 serves several purposes:
2832 - the same features can be used for other OS or standalone
2833 applications (for instance: using compressed images to reduce the
2834 Flash memory footprint)
2836 - it becomes much easier to port new Linux kernel versions because
2837 lots of low-level, hardware dependent stuff are done by U-Boot
2839 - the same Linux kernel image can now be used with different "initrd"
2840 images; of course this also means that different kernel images can
2841 be run with the same "initrd". This makes testing easier (you don't
2842 have to build a new "zImage.initrd" Linux image when you just
2843 change a file in your "initrd"). Also, a field-upgrade of the
2844 software is easier now.
2850 Porting Linux to U-Boot based systems:
2851 ---------------------------------------
2853 U-Boot cannot save you from doing all the necessary modifications to
2854 configure the Linux device drivers for use with your target hardware
2855 (no, we don't intend to provide a full virtual machine interface to
2858 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2860 Just make sure your machine specific header file (for instance
2861 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2862 Information structure as we define in include/asm-<arch>/u-boot.h,
2863 and make sure that your definition of IMAP_ADDR uses the same value
2864 as your U-Boot configuration in CONFIG_SYS_IMMR.
2866 Note that U-Boot now has a driver model, a unified model for drivers.
2867 If you are adding a new driver, plumb it into driver model. If there
2868 is no uclass available, you are encouraged to create one. See
2872 Configuring the Linux kernel:
2873 -----------------------------
2875 No specific requirements for U-Boot. Make sure you have some root
2876 device (initial ramdisk, NFS) for your target system.
2879 Building a Linux Image:
2880 -----------------------
2882 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2883 not used. If you use recent kernel source, a new build target
2884 "uImage" will exist which automatically builds an image usable by
2885 U-Boot. Most older kernels also have support for a "pImage" target,
2886 which was introduced for our predecessor project PPCBoot and uses a
2887 100% compatible format.
2891 make TQM850L_defconfig
2896 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2897 encapsulate a compressed Linux kernel image with header information,
2898 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2900 * build a standard "vmlinux" kernel image (in ELF binary format):
2902 * convert the kernel into a raw binary image:
2904 ${CROSS_COMPILE}-objcopy -O binary \
2905 -R .note -R .comment \
2906 -S vmlinux linux.bin
2908 * compress the binary image:
2912 * package compressed binary image for U-Boot:
2914 mkimage -A ppc -O linux -T kernel -C gzip \
2915 -a 0 -e 0 -n "Linux Kernel Image" \
2916 -d linux.bin.gz uImage
2919 The "mkimage" tool can also be used to create ramdisk images for use
2920 with U-Boot, either separated from the Linux kernel image, or
2921 combined into one file. "mkimage" encapsulates the images with a 64
2922 byte header containing information about target architecture,
2923 operating system, image type, compression method, entry points, time
2924 stamp, CRC32 checksums, etc.
2926 "mkimage" can be called in two ways: to verify existing images and
2927 print the header information, or to build new images.
2929 In the first form (with "-l" option) mkimage lists the information
2930 contained in the header of an existing U-Boot image; this includes
2931 checksum verification:
2933 tools/mkimage -l image
2934 -l ==> list image header information
2936 The second form (with "-d" option) is used to build a U-Boot image
2937 from a "data file" which is used as image payload:
2939 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2940 -n name -d data_file image
2941 -A ==> set architecture to 'arch'
2942 -O ==> set operating system to 'os'
2943 -T ==> set image type to 'type'
2944 -C ==> set compression type 'comp'
2945 -a ==> set load address to 'addr' (hex)
2946 -e ==> set entry point to 'ep' (hex)
2947 -n ==> set image name to 'name'
2948 -d ==> use image data from 'datafile'
2950 Right now, all Linux kernels for PowerPC systems use the same load
2951 address (0x00000000), but the entry point address depends on the
2954 - 2.2.x kernels have the entry point at 0x0000000C,
2955 - 2.3.x and later kernels have the entry point at 0x00000000.
2957 So a typical call to build a U-Boot image would read:
2959 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2960 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2961 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2962 > examples/uImage.TQM850L
2963 Image Name: 2.4.4 kernel for TQM850L
2964 Created: Wed Jul 19 02:34:59 2000
2965 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2966 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2967 Load Address: 0x00000000
2968 Entry Point: 0x00000000
2970 To verify the contents of the image (or check for corruption):
2972 -> tools/mkimage -l examples/uImage.TQM850L
2973 Image Name: 2.4.4 kernel for TQM850L
2974 Created: Wed Jul 19 02:34:59 2000
2975 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2976 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2977 Load Address: 0x00000000
2978 Entry Point: 0x00000000
2980 NOTE: for embedded systems where boot time is critical you can trade
2981 speed for memory and install an UNCOMPRESSED image instead: this
2982 needs more space in Flash, but boots much faster since it does not
2983 need to be uncompressed:
2985 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2986 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2987 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2988 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2989 > examples/uImage.TQM850L-uncompressed
2990 Image Name: 2.4.4 kernel for TQM850L
2991 Created: Wed Jul 19 02:34:59 2000
2992 Image Type: PowerPC Linux Kernel Image (uncompressed)
2993 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2994 Load Address: 0x00000000
2995 Entry Point: 0x00000000
2998 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2999 when your kernel is intended to use an initial ramdisk:
3001 -> tools/mkimage -n 'Simple Ramdisk Image' \
3002 > -A ppc -O linux -T ramdisk -C gzip \
3003 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
3004 Image Name: Simple Ramdisk Image
3005 Created: Wed Jan 12 14:01:50 2000
3006 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3007 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
3008 Load Address: 0x00000000
3009 Entry Point: 0x00000000
3011 The "dumpimage" tool can be used to disassemble or list the contents of images
3012 built by mkimage. See dumpimage's help output (-h) for details.
3014 Installing a Linux Image:
3015 -------------------------
3017 To downloading a U-Boot image over the serial (console) interface,
3018 you must convert the image to S-Record format:
3020 objcopy -I binary -O srec examples/image examples/image.srec
3022 The 'objcopy' does not understand the information in the U-Boot
3023 image header, so the resulting S-Record file will be relative to
3024 address 0x00000000. To load it to a given address, you need to
3025 specify the target address as 'offset' parameter with the 'loads'
3028 Example: install the image to address 0x40100000 (which on the
3029 TQM8xxL is in the first Flash bank):
3031 => erase 40100000 401FFFFF
3037 ## Ready for S-Record download ...
3038 ~>examples/image.srec
3039 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
3041 15989 15990 15991 15992
3042 [file transfer complete]
3044 ## Start Addr = 0x00000000
3047 You can check the success of the download using the 'iminfo' command;
3048 this includes a checksum verification so you can be sure no data
3049 corruption happened:
3053 ## Checking Image at 40100000 ...
3054 Image Name: 2.2.13 for initrd on TQM850L
3055 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3056 Data Size: 335725 Bytes = 327 kB = 0 MB
3057 Load Address: 00000000
3058 Entry Point: 0000000c
3059 Verifying Checksum ... OK
3065 The "bootm" command is used to boot an application that is stored in
3066 memory (RAM or Flash). In case of a Linux kernel image, the contents
3067 of the "bootargs" environment variable is passed to the kernel as
3068 parameters. You can check and modify this variable using the
3069 "printenv" and "setenv" commands:
3072 => printenv bootargs
3073 bootargs=root=/dev/ram
3075 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3077 => printenv bootargs
3078 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3081 ## Booting Linux kernel at 40020000 ...
3082 Image Name: 2.2.13 for NFS on TQM850L
3083 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3084 Data Size: 381681 Bytes = 372 kB = 0 MB
3085 Load Address: 00000000
3086 Entry Point: 0000000c
3087 Verifying Checksum ... OK
3088 Uncompressing Kernel Image ... OK
3089 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
3090 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
3091 time_init: decrementer frequency = 187500000/60
3092 Calibrating delay loop... 49.77 BogoMIPS
3093 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
3096 If you want to boot a Linux kernel with initial RAM disk, you pass
3097 the memory addresses of both the kernel and the initrd image (PPBCOOT
3098 format!) to the "bootm" command:
3100 => imi 40100000 40200000
3102 ## Checking Image at 40100000 ...
3103 Image Name: 2.2.13 for initrd on TQM850L
3104 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3105 Data Size: 335725 Bytes = 327 kB = 0 MB
3106 Load Address: 00000000
3107 Entry Point: 0000000c
3108 Verifying Checksum ... OK
3110 ## Checking Image at 40200000 ...
3111 Image Name: Simple Ramdisk Image
3112 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3113 Data Size: 566530 Bytes = 553 kB = 0 MB
3114 Load Address: 00000000
3115 Entry Point: 00000000
3116 Verifying Checksum ... OK
3118 => bootm 40100000 40200000
3119 ## Booting Linux kernel at 40100000 ...
3120 Image Name: 2.2.13 for initrd on TQM850L
3121 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3122 Data Size: 335725 Bytes = 327 kB = 0 MB
3123 Load Address: 00000000
3124 Entry Point: 0000000c
3125 Verifying Checksum ... OK
3126 Uncompressing Kernel Image ... OK
3127 ## Loading RAMDisk Image at 40200000 ...
3128 Image Name: Simple Ramdisk Image
3129 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
3130 Data Size: 566530 Bytes = 553 kB = 0 MB
3131 Load Address: 00000000
3132 Entry Point: 00000000
3133 Verifying Checksum ... OK
3134 Loading Ramdisk ... OK
3135 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
3136 Boot arguments: root=/dev/ram
3137 time_init: decrementer frequency = 187500000/60
3138 Calibrating delay loop... 49.77 BogoMIPS
3140 RAMDISK: Compressed image found at block 0
3141 VFS: Mounted root (ext2 filesystem).
3145 Boot Linux and pass a flat device tree:
3148 First, U-Boot must be compiled with the appropriate defines. See the section
3149 titled "Linux Kernel Interface" above for a more in depth explanation. The
3150 following is an example of how to start a kernel and pass an updated
3156 oft=oftrees/mpc8540ads.dtb
3157 => tftp $oftaddr $oft
3158 Speed: 1000, full duplex
3160 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
3161 Filename 'oftrees/mpc8540ads.dtb'.
3162 Load address: 0x300000
3165 Bytes transferred = 4106 (100a hex)
3166 => tftp $loadaddr $bootfile
3167 Speed: 1000, full duplex
3169 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
3171 Load address: 0x200000
3172 Loading:############
3174 Bytes transferred = 1029407 (fb51f hex)
3179 => bootm $loadaddr - $oftaddr
3180 ## Booting image at 00200000 ...
3181 Image Name: Linux-2.6.17-dirty
3182 Image Type: PowerPC Linux Kernel Image (gzip compressed)
3183 Data Size: 1029343 Bytes = 1005.2 kB
3184 Load Address: 00000000
3185 Entry Point: 00000000
3186 Verifying Checksum ... OK
3187 Uncompressing Kernel Image ... OK
3188 Booting using flat device tree at 0x300000
3189 Using MPC85xx ADS machine description
3190 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
3194 More About U-Boot Image Types:
3195 ------------------------------
3197 U-Boot supports the following image types:
3199 "Standalone Programs" are directly runnable in the environment
3200 provided by U-Boot; it is expected that (if they behave
3201 well) you can continue to work in U-Boot after return from
3202 the Standalone Program.
3203 "OS Kernel Images" are usually images of some Embedded OS which
3204 will take over control completely. Usually these programs
3205 will install their own set of exception handlers, device
3206 drivers, set up the MMU, etc. - this means, that you cannot
3207 expect to re-enter U-Boot except by resetting the CPU.
3208 "RAMDisk Images" are more or less just data blocks, and their
3209 parameters (address, size) are passed to an OS kernel that is
3211 "Multi-File Images" contain several images, typically an OS
3212 (Linux) kernel image and one or more data images like
3213 RAMDisks. This construct is useful for instance when you want
3214 to boot over the network using BOOTP etc., where the boot
3215 server provides just a single image file, but you want to get
3216 for instance an OS kernel and a RAMDisk image.
3218 "Multi-File Images" start with a list of image sizes, each
3219 image size (in bytes) specified by an "uint32_t" in network
3220 byte order. This list is terminated by an "(uint32_t)0".
3221 Immediately after the terminating 0 follow the images, one by
3222 one, all aligned on "uint32_t" boundaries (size rounded up to
3223 a multiple of 4 bytes).
3225 "Firmware Images" are binary images containing firmware (like
3226 U-Boot or FPGA images) which usually will be programmed to
3229 "Script files" are command sequences that will be executed by
3230 U-Boot's command interpreter; this feature is especially
3231 useful when you configure U-Boot to use a real shell (hush)
3232 as command interpreter.
3234 Booting the Linux zImage:
3235 -------------------------
3237 On some platforms, it's possible to boot Linux zImage. This is done
3238 using the "bootz" command. The syntax of "bootz" command is the same
3239 as the syntax of "bootm" command.
3241 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
3242 kernel with raw initrd images. The syntax is slightly different, the
3243 address of the initrd must be augmented by it's size, in the following
3244 format: "<initrd addres>:<initrd size>".
3250 One of the features of U-Boot is that you can dynamically load and
3251 run "standalone" applications, which can use some resources of
3252 U-Boot like console I/O functions or interrupt services.
3254 Two simple examples are included with the sources:
3259 'examples/hello_world.c' contains a small "Hello World" Demo
3260 application; it is automatically compiled when you build U-Boot.
3261 It's configured to run at address 0x00040004, so you can play with it
3265 ## Ready for S-Record download ...
3266 ~>examples/hello_world.srec
3267 1 2 3 4 5 6 7 8 9 10 11 ...
3268 [file transfer complete]
3270 ## Start Addr = 0x00040004
3272 => go 40004 Hello World! This is a test.
3273 ## Starting application at 0x00040004 ...
3284 Hit any key to exit ...
3286 ## Application terminated, rc = 0x0
3288 Another example, which demonstrates how to register a CPM interrupt
3289 handler with the U-Boot code, can be found in 'examples/timer.c'.
3290 Here, a CPM timer is set up to generate an interrupt every second.
3291 The interrupt service routine is trivial, just printing a '.'
3292 character, but this is just a demo program. The application can be
3293 controlled by the following keys:
3295 ? - print current values og the CPM Timer registers
3296 b - enable interrupts and start timer
3297 e - stop timer and disable interrupts
3298 q - quit application
3301 ## Ready for S-Record download ...
3302 ~>examples/timer.srec
3303 1 2 3 4 5 6 7 8 9 10 11 ...
3304 [file transfer complete]
3306 ## Start Addr = 0x00040004
3309 ## Starting application at 0x00040004 ...
3312 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
3315 [q, b, e, ?] Set interval 1000000 us
3318 [q, b, e, ?] ........
3319 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
3322 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
3325 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
3328 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
3330 [q, b, e, ?] ...Stopping timer
3332 [q, b, e, ?] ## Application terminated, rc = 0x0
3338 Over time, many people have reported problems when trying to use the
3339 "minicom" terminal emulation program for serial download. I (wd)
3340 consider minicom to be broken, and recommend not to use it. Under
3341 Unix, I recommend to use C-Kermit for general purpose use (and
3342 especially for kermit binary protocol download ("loadb" command), and
3343 use "cu" for S-Record download ("loads" command). See
3344 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
3345 for help with kermit.
3348 Nevertheless, if you absolutely want to use it try adding this
3349 configuration to your "File transfer protocols" section:
3351 Name Program Name U/D FullScr IO-Red. Multi
3352 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
3353 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
3359 Starting at version 0.9.2, U-Boot supports NetBSD both as host
3360 (build U-Boot) and target system (boots NetBSD/mpc8xx).
3362 Building requires a cross environment; it is known to work on
3363 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
3364 need gmake since the Makefiles are not compatible with BSD make).
3365 Note that the cross-powerpc package does not install include files;
3366 attempting to build U-Boot will fail because <machine/ansi.h> is
3367 missing. This file has to be installed and patched manually:
3369 # cd /usr/pkg/cross/powerpc-netbsd/include
3371 # ln -s powerpc machine
3372 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
3373 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
3375 Native builds *don't* work due to incompatibilities between native
3376 and U-Boot include files.
3378 Booting assumes that (the first part of) the image booted is a
3379 stage-2 loader which in turn loads and then invokes the kernel
3380 proper. Loader sources will eventually appear in the NetBSD source
3381 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
3382 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
3385 Implementation Internals:
3386 =========================
3388 The following is not intended to be a complete description of every
3389 implementation detail. However, it should help to understand the
3390 inner workings of U-Boot and make it easier to port it to custom
3394 Initial Stack, Global Data:
3395 ---------------------------
3397 The implementation of U-Boot is complicated by the fact that U-Boot
3398 starts running out of ROM (flash memory), usually without access to
3399 system RAM (because the memory controller is not initialized yet).
3400 This means that we don't have writable Data or BSS segments, and BSS
3401 is not initialized as zero. To be able to get a C environment working
3402 at all, we have to allocate at least a minimal stack. Implementation
3403 options for this are defined and restricted by the CPU used: Some CPU
3404 models provide on-chip memory (like the IMMR area on MPC8xx and
3405 MPC826x processors), on others (parts of) the data cache can be
3406 locked as (mis-) used as memory, etc.
3408 Chris Hallinan posted a good summary of these issues to the
3409 U-Boot mailing list:
3411 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
3412 From: "Chris Hallinan" <clh@net1plus.com>
3413 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
3416 Correct me if I'm wrong, folks, but the way I understand it
3417 is this: Using DCACHE as initial RAM for Stack, etc, does not
3418 require any physical RAM backing up the cache. The cleverness
3419 is that the cache is being used as a temporary supply of
3420 necessary storage before the SDRAM controller is setup. It's
3421 beyond the scope of this list to explain the details, but you
3422 can see how this works by studying the cache architecture and
3423 operation in the architecture and processor-specific manuals.
3425 OCM is On Chip Memory, which I believe the 405GP has 4K. It
3426 is another option for the system designer to use as an
3427 initial stack/RAM area prior to SDRAM being available. Either
3428 option should work for you. Using CS 4 should be fine if your
3429 board designers haven't used it for something that would
3430 cause you grief during the initial boot! It is frequently not
3433 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
3434 with your processor/board/system design. The default value
3435 you will find in any recent u-boot distribution in
3436 walnut.h should work for you. I'd set it to a value larger
3437 than your SDRAM module. If you have a 64MB SDRAM module, set
3438 it above 400_0000. Just make sure your board has no resources
3439 that are supposed to respond to that address! That code in
3440 start.S has been around a while and should work as is when
3441 you get the config right.
3446 It is essential to remember this, since it has some impact on the C
3447 code for the initialization procedures:
3449 * Initialized global data (data segment) is read-only. Do not attempt
3452 * Do not use any uninitialized global data (or implicitly initialized
3453 as zero data - BSS segment) at all - this is undefined, initiali-
3454 zation is performed later (when relocating to RAM).
3456 * Stack space is very limited. Avoid big data buffers or things like
3459 Having only the stack as writable memory limits means we cannot use
3460 normal global data to share information between the code. But it
3461 turned out that the implementation of U-Boot can be greatly
3462 simplified by making a global data structure (gd_t) available to all
3463 functions. We could pass a pointer to this data as argument to _all_
3464 functions, but this would bloat the code. Instead we use a feature of
3465 the GCC compiler (Global Register Variables) to share the data: we
3466 place a pointer (gd) to the global data into a register which we
3467 reserve for this purpose.
3469 When choosing a register for such a purpose we are restricted by the
3470 relevant (E)ABI specifications for the current architecture, and by
3471 GCC's implementation.
3473 For PowerPC, the following registers have specific use:
3475 R2: reserved for system use
3476 R3-R4: parameter passing and return values
3477 R5-R10: parameter passing
3478 R13: small data area pointer
3482 (U-Boot also uses R12 as internal GOT pointer. r12
3483 is a volatile register so r12 needs to be reset when
3484 going back and forth between asm and C)
3486 ==> U-Boot will use R2 to hold a pointer to the global data
3488 Note: on PPC, we could use a static initializer (since the
3489 address of the global data structure is known at compile time),
3490 but it turned out that reserving a register results in somewhat
3491 smaller code - although the code savings are not that big (on
3492 average for all boards 752 bytes for the whole U-Boot image,
3493 624 text + 127 data).
3495 On ARM, the following registers are used:
3497 R0: function argument word/integer result
3498 R1-R3: function argument word
3499 R9: platform specific
3500 R10: stack limit (used only if stack checking is enabled)
3501 R11: argument (frame) pointer
3502 R12: temporary workspace
3505 R15: program counter
3507 ==> U-Boot will use R9 to hold a pointer to the global data
3509 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3511 On Nios II, the ABI is documented here:
3512 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3514 ==> U-Boot will use gp to hold a pointer to the global data
3516 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3517 to access small data sections, so gp is free.
3519 On NDS32, the following registers are used:
3521 R0-R1: argument/return
3523 R15: temporary register for assembler
3524 R16: trampoline register
3525 R28: frame pointer (FP)
3526 R29: global pointer (GP)
3527 R30: link register (LP)
3528 R31: stack pointer (SP)
3529 PC: program counter (PC)
3531 ==> U-Boot will use R10 to hold a pointer to the global data
3533 NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
3534 or current versions of GCC may "optimize" the code too much.
3536 On RISC-V, the following registers are used:
3538 x0: hard-wired zero (zero)
3539 x1: return address (ra)
3540 x2: stack pointer (sp)
3541 x3: global pointer (gp)
3542 x4: thread pointer (tp)
3543 x5: link register (t0)
3544 x8: frame pointer (fp)
3545 x10-x11: arguments/return values (a0-1)
3546 x12-x17: arguments (a2-7)
3547 x28-31: temporaries (t3-6)
3548 pc: program counter (pc)
3550 ==> U-Boot will use gp to hold a pointer to the global data
3555 U-Boot runs in system state and uses physical addresses, i.e. the
3556 MMU is not used either for address mapping nor for memory protection.
3558 The available memory is mapped to fixed addresses using the memory
3559 controller. In this process, a contiguous block is formed for each
3560 memory type (Flash, SDRAM, SRAM), even when it consists of several
3561 physical memory banks.
3563 U-Boot is installed in the first 128 kB of the first Flash bank (on
3564 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3565 booting and sizing and initializing DRAM, the code relocates itself
3566 to the upper end of DRAM. Immediately below the U-Boot code some
3567 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3568 configuration setting]. Below that, a structure with global Board
3569 Info data is placed, followed by the stack (growing downward).
3571 Additionally, some exception handler code is copied to the low 8 kB
3572 of DRAM (0x00000000 ... 0x00001FFF).
3574 So a typical memory configuration with 16 MB of DRAM could look like
3577 0x0000 0000 Exception Vector code
3580 0x0000 2000 Free for Application Use
3586 0x00FB FF20 Monitor Stack (Growing downward)
3587 0x00FB FFAC Board Info Data and permanent copy of global data
3588 0x00FC 0000 Malloc Arena
3591 0x00FE 0000 RAM Copy of Monitor Code
3592 ... eventually: LCD or video framebuffer
3593 ... eventually: pRAM (Protected RAM - unchanged by reset)
3594 0x00FF FFFF [End of RAM]
3597 System Initialization:
3598 ----------------------
3600 In the reset configuration, U-Boot starts at the reset entry point
3601 (on most PowerPC systems at address 0x00000100). Because of the reset
3602 configuration for CS0# this is a mirror of the on board Flash memory.
3603 To be able to re-map memory U-Boot then jumps to its link address.
3604 To be able to implement the initialization code in C, a (small!)
3605 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3606 which provide such a feature like), or in a locked part of the data
3607 cache. After that, U-Boot initializes the CPU core, the caches and
3610 Next, all (potentially) available memory banks are mapped using a
3611 preliminary mapping. For example, we put them on 512 MB boundaries
3612 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3613 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3614 programmed for SDRAM access. Using the temporary configuration, a
3615 simple memory test is run that determines the size of the SDRAM
3618 When there is more than one SDRAM bank, and the banks are of
3619 different size, the largest is mapped first. For equal size, the first
3620 bank (CS2#) is mapped first. The first mapping is always for address
3621 0x00000000, with any additional banks following immediately to create
3622 contiguous memory starting from 0.
3624 Then, the monitor installs itself at the upper end of the SDRAM area
3625 and allocates memory for use by malloc() and for the global Board
3626 Info data; also, the exception vector code is copied to the low RAM
3627 pages, and the final stack is set up.
3629 Only after this relocation will you have a "normal" C environment;
3630 until that you are restricted in several ways, mostly because you are
3631 running from ROM, and because the code will have to be relocated to a
3635 U-Boot Porting Guide:
3636 ----------------------
3638 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3642 int main(int argc, char *argv[])
3644 sighandler_t no_more_time;
3646 signal(SIGALRM, no_more_time);
3647 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3649 if (available_money > available_manpower) {
3650 Pay consultant to port U-Boot;
3654 Download latest U-Boot source;
3656 Subscribe to u-boot mailing list;
3659 email("Hi, I am new to U-Boot, how do I get started?");
3662 Read the README file in the top level directory;
3663 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3664 Read applicable doc/README.*;
3665 Read the source, Luke;
3666 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3669 if (available_money > toLocalCurrency ($2500))
3672 Add a lot of aggravation and time;
3674 if (a similar board exists) { /* hopefully... */
3675 cp -a board/<similar> board/<myboard>
3676 cp include/configs/<similar>.h include/configs/<myboard>.h
3678 Create your own board support subdirectory;
3679 Create your own board include/configs/<myboard>.h file;
3681 Edit new board/<myboard> files
3682 Edit new include/configs/<myboard>.h
3687 Add / modify source code;
3691 email("Hi, I am having problems...");
3693 Send patch file to the U-Boot email list;
3694 if (reasonable critiques)
3695 Incorporate improvements from email list code review;
3697 Defend code as written;
3703 void no_more_time (int sig)
3712 All contributions to U-Boot should conform to the Linux kernel
3713 coding style; see the kernel coding style guide at
3714 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3715 script "scripts/Lindent" in your Linux kernel source directory.
3717 Source files originating from a different project (for example the
3718 MTD subsystem) are generally exempt from these guidelines and are not
3719 reformatted to ease subsequent migration to newer versions of those
3722 Please note that U-Boot is implemented in C (and to some small parts in
3723 Assembler); no C++ is used, so please do not use C++ style comments (//)
3726 Please also stick to the following formatting rules:
3727 - remove any trailing white space
3728 - use TAB characters for indentation and vertical alignment, not spaces
3729 - make sure NOT to use DOS '\r\n' line feeds
3730 - do not add more than 2 consecutive empty lines to source files
3731 - do not add trailing empty lines to source files
3733 Submissions which do not conform to the standards may be returned
3734 with a request to reformat the changes.
3740 Since the number of patches for U-Boot is growing, we need to
3741 establish some rules. Submissions which do not conform to these rules
3742 may be rejected, even when they contain important and valuable stuff.
3744 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3746 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3747 see https://lists.denx.de/listinfo/u-boot
3749 When you send a patch, please include the following information with
3752 * For bug fixes: a description of the bug and how your patch fixes
3753 this bug. Please try to include a way of demonstrating that the
3754 patch actually fixes something.
3756 * For new features: a description of the feature and your
3759 * For major contributions, add a MAINTAINERS file with your
3760 information and associated file and directory references.
3762 * When you add support for a new board, don't forget to add a
3763 maintainer e-mail address to the boards.cfg file, too.
3765 * If your patch adds new configuration options, don't forget to
3766 document these in the README file.
3768 * The patch itself. If you are using git (which is *strongly*
3769 recommended) you can easily generate the patch using the
3770 "git format-patch". If you then use "git send-email" to send it to
3771 the U-Boot mailing list, you will avoid most of the common problems
3772 with some other mail clients.
3774 If you cannot use git, use "diff -purN OLD NEW". If your version of
3775 diff does not support these options, then get the latest version of
3778 The current directory when running this command shall be the parent
3779 directory of the U-Boot source tree (i. e. please make sure that
3780 your patch includes sufficient directory information for the
3783 We prefer patches as plain text. MIME attachments are discouraged,
3784 and compressed attachments must not be used.
3786 * If one logical set of modifications affects or creates several
3787 files, all these changes shall be submitted in a SINGLE patch file.
3789 * Changesets that contain different, unrelated modifications shall be
3790 submitted as SEPARATE patches, one patch per changeset.
3795 * Before sending the patch, run the buildman script on your patched
3796 source tree and make sure that no errors or warnings are reported
3797 for any of the boards.
3799 * Keep your modifications to the necessary minimum: A patch
3800 containing several unrelated changes or arbitrary reformats will be
3801 returned with a request to re-formatting / split it.
3803 * If you modify existing code, make sure that your new code does not
3804 add to the memory footprint of the code ;-) Small is beautiful!
3805 When adding new features, these should compile conditionally only
3806 (using #ifdef), and the resulting code with the new feature
3807 disabled must not need more memory than the old code without your
3810 * Remember that there is a size limit of 100 kB per message on the
3811 u-boot mailing list. Bigger patches will be moderated. If they are
3812 reasonable and not too big, they will be acknowledged. But patches
3813 bigger than the size limit should be avoided.