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 /nios2 Files generic to Altera NIOS2 architecture
138 /powerpc Files generic to PowerPC architecture
139 /riscv Files generic to RISC-V architecture
140 /sandbox Files generic to HW-independent "sandbox"
141 /sh Files generic to SH architecture
142 /x86 Files generic to x86 architecture
143 /xtensa Files generic to Xtensa architecture
144 /api Machine/arch-independent API for external apps
145 /board Board-dependent files
146 /boot Support for images and booting
147 /cmd U-Boot commands functions
148 /common Misc architecture-independent functions
149 /configs Board default configuration files
150 /disk Code for disk drive partition handling
151 /doc Documentation (a mix of ReST and READMEs)
152 /drivers Device drivers
153 /dts Makefile for building internal U-Boot fdt.
154 /env Environment support
155 /examples Example code for standalone applications, etc.
156 /fs Filesystem code (cramfs, ext2, jffs2, etc.)
157 /include Header Files
158 /lib Library routines generic to all architectures
159 /Licenses Various license files
161 /post Power On Self Test
162 /scripts Various build scripts and Makefiles
163 /test Various unit test files
164 /tools Tools to build and sign FIT images, etc.
166 Software Configuration:
167 =======================
169 Selection of Processor Architecture and Board Type:
170 ---------------------------------------------------
172 For all supported boards there are ready-to-use default
173 configurations available; just type "make <board_name>_defconfig".
175 Example: For a TQM823L module type:
178 make TQM823L_defconfig
180 Note: If you're looking for the default configuration file for a board
181 you're sure used to be there but is now missing, check the file
182 doc/README.scrapyard for a list of no longer supported boards.
187 U-Boot can be built natively to run on a Linux host using the 'sandbox'
188 board. This allows feature development which is not board- or architecture-
189 specific to be undertaken on a native platform. The sandbox is also used to
190 run some of U-Boot's tests.
192 See doc/arch/sandbox.rst for more details.
195 Board Initialisation Flow:
196 --------------------------
198 This is the intended start-up flow for boards. This should apply for both
199 SPL and U-Boot proper (i.e. they both follow the same rules).
201 Note: "SPL" stands for "Secondary Program Loader," which is explained in
202 more detail later in this file.
204 At present, SPL mostly uses a separate code path, but the function names
205 and roles of each function are the same. Some boards or architectures
206 may not conform to this. At least most ARM boards which use
207 CONFIG_SPL_FRAMEWORK conform to this.
209 Execution typically starts with an architecture-specific (and possibly
210 CPU-specific) start.S file, such as:
212 - arch/arm/cpu/armv7/start.S
213 - arch/powerpc/cpu/mpc83xx/start.S
214 - arch/mips/cpu/start.S
216 and so on. From there, three functions are called; the purpose and
217 limitations of each of these functions are described below.
220 - purpose: essential init to permit execution to reach board_init_f()
221 - no global_data or BSS
222 - there is no stack (ARMv7 may have one but it will soon be removed)
223 - must not set up SDRAM or use console
224 - must only do the bare minimum to allow execution to continue to
226 - this is almost never needed
227 - return normally from this function
230 - purpose: set up the machine ready for running board_init_r():
231 i.e. SDRAM and serial UART
232 - global_data is available
234 - BSS is not available, so you cannot use global/static variables,
235 only stack variables and global_data
237 Non-SPL-specific notes:
238 - dram_init() is called to set up DRAM. If already done in SPL this
242 - you can override the entire board_init_f() function with your own
244 - preloader_console_init() can be called here in extremis
245 - should set up SDRAM, and anything needed to make the UART work
246 - there is no need to clear BSS, it will be done by crt0.S
247 - for specific scenarios on certain architectures an early BSS *can*
248 be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
249 of BSS prior to entering board_init_f()) but doing so is discouraged.
250 Instead it is strongly recommended to architect any code changes
251 or additions such to not depend on the availability of BSS during
252 board_init_f() as indicated in other sections of this README to
253 maintain compatibility and consistency across the entire code base.
254 - must return normally from this function (don't call board_init_r()
257 Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
258 this point the stack and global_data are relocated to below
259 CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
263 - purpose: main execution, common code
264 - global_data is available
266 - BSS is available, all static/global variables can be used
267 - execution eventually continues to main_loop()
269 Non-SPL-specific notes:
270 - U-Boot is relocated to the top of memory and is now running from
274 - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
275 CONFIG_SYS_FSL_HAS_CCI400
277 Defined For SoC that has cache coherent interconnect
280 CONFIG_SYS_FSL_HAS_CCN504
282 Defined for SoC that has cache coherent interconnect CCN-504
284 The following options need to be configured:
286 - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
288 - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
293 Specifies that the core is a 64-bit PowerPC implementation (implements
294 the "64" category of the Power ISA). This is necessary for ePAPR
295 compliance, among other possible reasons.
297 CONFIG_SYS_FSL_TBCLK_DIV
299 Defines the core time base clock divider ratio compared to the
300 system clock. On most PQ3 devices this is 8, on newer QorIQ
301 devices it can be 16 or 32. The ratio varies from SoC to Soc.
303 CONFIG_SYS_FSL_PCIE_COMPAT
305 Defines the string to utilize when trying to match PCIe device
306 tree nodes for the given platform.
308 CONFIG_SYS_FSL_ERRATUM_A004510
310 Enables a workaround for erratum A004510. If set,
311 then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
312 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
314 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
315 CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
317 Defines one or two SoC revisions (low 8 bits of SVR)
318 for which the A004510 workaround should be applied.
320 The rest of SVR is either not relevant to the decision
321 of whether the erratum is present (e.g. p2040 versus
322 p2041) or is implied by the build target, which controls
323 whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
325 See Freescale App Note 4493 for more information about
328 CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
330 This is the value to write into CCSR offset 0x18600
331 according to the A004510 workaround.
333 CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
334 Single Source Clock is clocking mode present in some of FSL SoC's.
335 In this mode, a single differential clock is used to supply
336 clocks to the sysclock, ddrclock and usbclock.
338 - Generic CPU options:
341 Freescale DDR driver in use. This type of DDR controller is
342 found in mpc83xx, mpc85xx as well as some ARM core SoCs.
344 CONFIG_SYS_FSL_DDR_ADDR
345 Freescale DDR memory-mapped register base.
347 CONFIG_SYS_FSL_IFC_CLK_DIV
348 Defines divider of platform clock(clock input to IFC controller).
350 CONFIG_SYS_FSL_LBC_CLK_DIV
351 Defines divider of platform clock(clock input to eLBC controller).
353 CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
354 Physical address from the view of DDR controllers. It is the
355 same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
356 it could be different for ARM SoCs.
359 CONFIG_XWAY_SWAP_BYTES
361 Enable compilation of tools/xway-swap-bytes needed for Lantiq
362 XWAY SoCs for booting from NOR flash. The U-Boot image needs to
363 be swapped if a flash programmer is used.
366 CONFIG_SYS_EXCEPTION_VECTORS_HIGH
368 Select high exception vectors of the ARM core, e.g., do not
369 clear the V bit of the c1 register of CP15.
372 Generic timer clock source frequency.
374 COUNTER_FREQUENCY_REAL
375 Generic timer clock source frequency if the real clock is
376 different from COUNTER_FREQUENCY, and can only be determined
380 CONFIG_TEGRA_SUPPORT_NON_SECURE
382 Support executing U-Boot in non-secure (NS) mode. Certain
383 impossible actions will be skipped if the CPU is in NS mode,
384 such as ARM architectural timer initialization.
386 - Linux Kernel Interface:
387 CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
389 When transferring memsize parameter to Linux, some versions
390 expect it to be in bytes, others in MB.
391 Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
395 New kernel versions are expecting firmware settings to be
396 passed using flattened device trees (based on open firmware
400 * New libfdt-based support
401 * Adds the "fdt" command
402 * The bootm command automatically updates the fdt
404 OF_TBCLK - The timebase frequency.
406 boards with QUICC Engines require OF_QE to set UCC MAC
411 U-Boot can detect if an IDE device is present or not.
412 If not, and this new config option is activated, U-Boot
413 removes the ATA node from the DTS before booting Linux,
414 so the Linux IDE driver does not probe the device and
415 crash. This is needed for buggy hardware (uc101) where
416 no pull down resistor is connected to the signal IDE5V_DD7.
418 - vxWorks boot parameters:
420 bootvx constructs a valid bootline using the following
421 environments variables: bootdev, bootfile, ipaddr, netmask,
422 serverip, gatewayip, hostname, othbootargs.
423 It loads the vxWorks image pointed bootfile.
425 Note: If a "bootargs" environment is defined, it will override
426 the defaults discussed just above.
428 - Cache Configuration for ARM:
429 CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
431 CONFIG_SYS_PL310_BASE - Physical base address of PL310
432 controller register space
437 If you have Amba PrimeCell PL011 UARTs, set this variable to
438 the clock speed of the UARTs.
442 If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
443 define this to a list of base addresses for each (supported)
444 port. See e.g. include/configs/versatile.h
446 CONFIG_SERIAL_HW_FLOW_CONTROL
448 Define this variable to enable hw flow control in serial driver.
449 Current user of this option is drivers/serial/nsl16550.c driver
451 - Serial Download Echo Mode:
453 If defined to 1, all characters received during a
454 serial download (using the "loads" command) are
455 echoed back. This might be needed by some terminal
456 emulations (like "cu"), but may as well just take
457 time on others. This setting #define's the initial
458 value of the "loads_echo" environment variable.
460 - Removal of commands
461 If no commands are needed to boot, you can disable
462 CONFIG_CMDLINE to remove them. In this case, the command line
463 will not be available, and when U-Boot wants to execute the
464 boot command (on start-up) it will call board_run_command()
465 instead. This can reduce image size significantly for very
466 simple boot procedures.
468 - Regular expression support:
470 If this variable is defined, U-Boot is linked against
471 the SLRE (Super Light Regular Expression) library,
472 which adds regex support to some commands, as for
473 example "env grep" and "setexpr".
476 CONFIG_SYS_WATCHDOG_FREQ
477 Some platforms automatically call WATCHDOG_RESET()
478 from the timer interrupt handler every
479 CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
480 board configuration file, a default of CONFIG_SYS_HZ/2
481 (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
482 to 0 disables calling WATCHDOG_RESET() from the timer
487 When CONFIG_CMD_DATE is selected, the type of the RTC
488 has to be selected, too. Define exactly one of the
491 CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
492 CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
493 CONFIG_RTC_MC146818 - use MC146818 RTC
494 CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
495 CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
496 CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
497 CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
498 CONFIG_RTC_DS164x - use Dallas DS164x RTC
499 CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
500 CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
501 CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
502 CONFIG_SYS_RV3029_TCR - enable trickle charger on
505 Note that if the RTC uses I2C, then the I2C interface
506 must also be configured. See I2C Support, below.
509 CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
511 The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
512 chip-ngpio pairs that tell the PCA953X driver the number of
513 pins supported by a particular chip.
515 Note that if the GPIO device uses I2C, then the I2C interface
516 must also be configured. See I2C Support, below.
519 When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
520 accesses and can checksum them or write a list of them out
521 to memory. See the 'iotrace' command for details. This is
522 useful for testing device drivers since it can confirm that
523 the driver behaves the same way before and after a code
524 change. Currently this is supported on sandbox and arm. To
525 add support for your architecture, add '#include <iotrace.h>'
526 to the bottom of arch/<arch>/include/asm/io.h and test.
528 Example output from the 'iotrace stats' command is below.
529 Note that if the trace buffer is exhausted, the checksum will
530 still continue to operate.
533 Start: 10000000 (buffer start address)
534 Size: 00010000 (buffer size)
535 Offset: 00000120 (current buffer offset)
536 Output: 10000120 (start + offset)
537 Count: 00000018 (number of trace records)
538 CRC32: 9526fb66 (CRC32 of all trace records)
542 When CONFIG_TIMESTAMP is selected, the timestamp
543 (date and time) of an image is printed by image
544 commands like bootm or iminfo. This option is
545 automatically enabled when you select CONFIG_CMD_DATE .
547 - Partition Labels (disklabels) Supported:
548 Zero or more of the following:
549 CONFIG_MAC_PARTITION Apple's MacOS partition table.
550 CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
551 CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
552 bootloader. Note 2TB partition limit; see
554 CONFIG_SCSI) you must configure support for at
555 least one non-MTD partition type as well.
557 - NETWORK Support (PCI):
559 Utility code for direct access to the SPI bus on Intel 8257x.
560 This does not do anything useful unless you set at least one
561 of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
564 Support for National dp83815 chips.
567 Support for National dp8382[01] gigabit chips.
569 - NETWORK Support (other):
571 Support for the Calxeda XGMAC device
574 Support for SMSC's LAN91C96 chips.
576 CONFIG_LAN91C96_USE_32_BIT
577 Define this to enable 32 bit addressing
580 Support for SMSC's LAN91C111 chip
583 Define this to hold the physical address
584 of the device (I/O space)
586 CONFIG_SMC_USE_32_BIT
587 Define this if data bus is 32 bits
589 CONFIG_SMC_USE_IOFUNCS
590 Define this to use i/o functions instead of macros
591 (some hardware wont work with macros)
593 CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
594 Define this if you have more then 3 PHYs.
597 Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
599 CONFIG_FTGMAC100_EGIGA
600 Define this to use GE link update with gigabit PHY.
601 Define this if FTGMAC100 is connected to gigabit PHY.
602 If your system has 10/100 PHY only, it might not occur
603 wrong behavior. Because PHY usually return timeout or
604 useless data when polling gigabit status and gigabit
605 control registers. This behavior won't affect the
606 correctnessof 10/100 link speed update.
609 Support for Renesas on-chip Ethernet controller
611 CONFIG_SH_ETHER_USE_PORT
612 Define the number of ports to be used
614 CONFIG_SH_ETHER_PHY_ADDR
615 Define the ETH PHY's address
617 CONFIG_SH_ETHER_CACHE_WRITEBACK
618 If this option is set, the driver enables cache flush.
624 CONFIG_TPM_TIS_INFINEON
625 Support for Infineon i2c bus TPM devices. Only one device
626 per system is supported at this time.
628 CONFIG_TPM_TIS_I2C_BURST_LIMITATION
629 Define the burst count bytes upper limit
632 Support for STMicroelectronics TPM devices. Requires DM_TPM support.
634 CONFIG_TPM_ST33ZP24_I2C
635 Support for STMicroelectronics ST33ZP24 I2C devices.
636 Requires TPM_ST33ZP24 and I2C.
638 CONFIG_TPM_ST33ZP24_SPI
639 Support for STMicroelectronics ST33ZP24 SPI devices.
640 Requires TPM_ST33ZP24 and SPI.
643 Support for Atmel TWI TPM device. Requires I2C support.
646 Support for generic parallel port TPM devices. Only one device
647 per system is supported at this time.
649 CONFIG_TPM_TIS_BASE_ADDRESS
650 Base address where the generic TPM device is mapped
651 to. Contemporary x86 systems usually map it at
655 Define this to enable the TPM support library which provides
656 functional interfaces to some TPM commands.
657 Requires support for a TPM device.
659 CONFIG_TPM_AUTH_SESSIONS
660 Define this to enable authorized functions in the TPM library.
661 Requires CONFIG_TPM and CONFIG_SHA1.
664 At the moment only the UHCI host controller is
665 supported (PIP405, MIP405); define
666 CONFIG_USB_UHCI to enable it.
667 define CONFIG_USB_KEYBOARD to enable the USB Keyboard
668 and define CONFIG_USB_STORAGE to enable the USB
671 Supported are USB Keyboards and USB Floppy drives
674 CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
678 Define the below if you wish to use the USB console.
679 Once firmware is rebuilt from a serial console issue the
680 command "setenv stdin usbtty; setenv stdout usbtty" and
681 attach your USB cable. The Unix command "dmesg" should print
682 it has found a new device. The environment variable usbtty
683 can be set to gserial or cdc_acm to enable your device to
684 appear to a USB host as a Linux gserial device or a
685 Common Device Class Abstract Control Model serial device.
686 If you select usbtty = gserial you should be able to enumerate
688 # modprobe usbserial vendor=0xVendorID product=0xProductID
689 else if using cdc_acm, simply setting the environment
690 variable usbtty to be cdc_acm should suffice. The following
691 might be defined in YourBoardName.h
694 Define this to build a UDC device
697 Define this to have a tty type of device available to
698 talk to the UDC device
701 Define this to enable the high speed support for usb
702 device and usbtty. If this feature is enabled, a routine
703 int is_usbd_high_speed(void)
704 also needs to be defined by the driver to dynamically poll
705 whether the enumeration has succeded at high speed or full
708 If you have a USB-IF assigned VendorID then you may wish to
709 define your own vendor specific values either in BoardName.h
710 or directly in usbd_vendor_info.h. If you don't define
711 CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
712 CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
713 should pretend to be a Linux device to it's target host.
715 CONFIG_USBD_MANUFACTURER
716 Define this string as the name of your company for
717 - CONFIG_USBD_MANUFACTURER "my company"
719 CONFIG_USBD_PRODUCT_NAME
720 Define this string as the name of your product
721 - CONFIG_USBD_PRODUCT_NAME "acme usb device"
724 Define this as your assigned Vendor ID from the USB
725 Implementors Forum. This *must* be a genuine Vendor ID
726 to avoid polluting the USB namespace.
727 - CONFIG_USBD_VENDORID 0xFFFF
729 CONFIG_USBD_PRODUCTID
730 Define this as the unique Product ID
732 - CONFIG_USBD_PRODUCTID 0xFFFF
734 - ULPI Layer Support:
735 The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
736 the generic ULPI layer. The generic layer accesses the ULPI PHY
737 via the platform viewport, so you need both the genric layer and
738 the viewport enabled. Currently only Chipidea/ARC based
739 viewport is supported.
740 To enable the ULPI layer support, define CONFIG_USB_ULPI and
741 CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
742 If your ULPI phy needs a different reference clock than the
743 standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
744 the appropriate value in Hz.
748 Support for Renesas on-chip MMCIF controller
751 Define the base address of MMCIF registers
754 Define the clock frequency for MMCIF
756 - USB Device Firmware Update (DFU) class support:
758 This enables the USB portion of the DFU USB class
761 This enables support for exposing NAND devices via DFU.
764 This enables support for exposing RAM via DFU.
765 Note: DFU spec refer to non-volatile memory usage, but
766 allow usages beyond the scope of spec - here RAM usage,
767 one that would help mostly the developer.
769 CONFIG_SYS_DFU_DATA_BUF_SIZE
770 Dfu transfer uses a buffer before writing data to the
771 raw storage device. Make the size (in bytes) of this buffer
772 configurable. The size of this buffer is also configurable
773 through the "dfu_bufsiz" environment variable.
775 CONFIG_SYS_DFU_MAX_FILE_SIZE
776 When updating files rather than the raw storage device,
777 we use a static buffer to copy the file into and then write
778 the buffer once we've been given the whole file. Define
779 this to the maximum filesize (in bytes) for the buffer.
780 Default is 4 MiB if undefined.
782 DFU_DEFAULT_POLL_TIMEOUT
783 Poll timeout [ms], is the timeout a device can send to the
784 host. The host must wait for this timeout before sending
785 a subsequent DFU_GET_STATUS request to the device.
787 DFU_MANIFEST_POLL_TIMEOUT
788 Poll timeout [ms], which the device sends to the host when
789 entering dfuMANIFEST state. Host waits this timeout, before
790 sending again an USB request to the device.
792 - Journaling Flash filesystem support:
793 CONFIG_SYS_JFFS2_FIRST_SECTOR,
794 CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
795 Define these for a default partition on a NOR device
798 See Kconfig help for available keyboard drivers.
800 - LCD Support: CONFIG_LCD
802 Define this to enable LCD support (for output to LCD
803 display); also select one of the supported displays
804 by defining one of these:
806 CONFIG_NEC_NL6448AC33:
808 NEC NL6448AC33-18. Active, color, single scan.
810 CONFIG_NEC_NL6448BC20
812 NEC NL6448BC20-08. 6.5", 640x480.
813 Active, color, single scan.
815 CONFIG_NEC_NL6448BC33_54
817 NEC NL6448BC33-54. 10.4", 640x480.
818 Active, color, single scan.
822 Sharp 320x240. Active, color, single scan.
823 It isn't 16x9, and I am not sure what it is.
825 CONFIG_SHARP_LQ64D341
827 Sharp LQ64D341 display, 640x480.
828 Active, color, single scan.
832 HLD1045 display, 640x480.
833 Active, color, single scan.
837 Optrex CBL50840-2 NF-FW 99 22 M5
839 Hitachi LMG6912RPFC-00T
843 320x240. Black & white.
847 Normally the LCD is page-aligned (typically 4KB). If this is
848 defined then the LCD will be aligned to this value instead.
849 For ARM it is sometimes useful to use MMU_SECTION_SIZE
850 here, since it is cheaper to change data cache settings on
856 Sometimes, for example if the display is mounted in portrait
857 mode or even if it's mounted landscape but rotated by 180degree,
858 we need to rotate our content of the display relative to the
859 framebuffer, so that user can read the messages which are
861 Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
862 initialized with a given rotation from "vl_rot" out of
863 "vidinfo_t" which is provided by the board specific code.
864 The value for vl_rot is coded as following (matching to
865 fbcon=rotate:<n> linux-kernel commandline):
866 0 = no rotation respectively 0 degree
867 1 = 90 degree rotation
868 2 = 180 degree rotation
869 3 = 270 degree rotation
871 If CONFIG_LCD_ROTATION is not defined, the console will be
872 initialized with 0degree rotation.
875 CONFIG_PHY_CLOCK_FREQ (ppc4xx)
877 The clock frequency of the MII bus
879 CONFIG_PHY_CMD_DELAY (ppc4xx)
881 Some PHY like Intel LXT971A need extra delay after
882 command issued before MII status register can be read
887 Define a default value for the IP address to use for
888 the default Ethernet interface, in case this is not
889 determined through e.g. bootp.
890 (Environment variable "ipaddr")
895 Defines a default value for the IP address of a TFTP
896 server to contact when using the "tftboot" command.
897 (Environment variable "serverip")
899 - Gateway IP address:
902 Defines a default value for the IP address of the
903 default router where packets to other networks are
905 (Environment variable "gatewayip")
910 Defines a default value for the subnet mask (or
911 routing prefix) which is used to determine if an IP
912 address belongs to the local subnet or needs to be
913 forwarded through a router.
914 (Environment variable "netmask")
916 - BOOTP Recovery Mode:
917 CONFIG_BOOTP_RANDOM_DELAY
919 If you have many targets in a network that try to
920 boot using BOOTP, you may want to avoid that all
921 systems send out BOOTP requests at precisely the same
922 moment (which would happen for instance at recovery
923 from a power failure, when all systems will try to
924 boot, thus flooding the BOOTP server. Defining
925 CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
926 inserted before sending out BOOTP requests. The
927 following delays are inserted then:
929 1st BOOTP request: delay 0 ... 1 sec
930 2nd BOOTP request: delay 0 ... 2 sec
931 3rd BOOTP request: delay 0 ... 4 sec
933 BOOTP requests: delay 0 ... 8 sec
935 CONFIG_BOOTP_ID_CACHE_SIZE
937 BOOTP packets are uniquely identified using a 32-bit ID. The
938 server will copy the ID from client requests to responses and
939 U-Boot will use this to determine if it is the destination of
940 an incoming response. Some servers will check that addresses
941 aren't in use before handing them out (usually using an ARP
942 ping) and therefore take up to a few hundred milliseconds to
943 respond. Network congestion may also influence the time it
944 takes for a response to make it back to the client. If that
945 time is too long, U-Boot will retransmit requests. In order
946 to allow earlier responses to still be accepted after these
947 retransmissions, U-Boot's BOOTP client keeps a small cache of
948 IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
949 cache. The default is to keep IDs for up to four outstanding
950 requests. Increasing this will allow U-Boot to accept offers
951 from a BOOTP client in networks with unusually high latency.
953 - DHCP Advanced Options:
955 - Link-local IP address negotiation:
956 Negotiate with other link-local clients on the local network
957 for an address that doesn't require explicit configuration.
958 This is especially useful if a DHCP server cannot be guaranteed
959 to exist in all environments that the device must operate.
961 See doc/README.link-local for more information.
963 - MAC address from environment variables
965 FDT_SEQ_MACADDR_FROM_ENV
967 Fix-up device tree with MAC addresses fetched sequentially from
968 environment variables. This config work on assumption that
969 non-usable ethernet node of device-tree are either not present
970 or their status has been marked as "disabled".
975 The device id used in CDP trigger frames.
977 CONFIG_CDP_DEVICE_ID_PREFIX
979 A two character string which is prefixed to the MAC address
984 A printf format string which contains the ascii name of
985 the port. Normally is set to "eth%d" which sets
986 eth0 for the first Ethernet, eth1 for the second etc.
988 CONFIG_CDP_CAPABILITIES
990 A 32bit integer which indicates the device capabilities;
991 0x00000010 for a normal host which does not forwards.
995 An ascii string containing the version of the software.
999 An ascii string containing the name of the platform.
1003 A 32bit integer sent on the trigger.
1005 CONFIG_CDP_POWER_CONSUMPTION
1007 A 16bit integer containing the power consumption of the
1008 device in .1 of milliwatts.
1010 CONFIG_CDP_APPLIANCE_VLAN_TYPE
1012 A byte containing the id of the VLAN.
1014 - Status LED: CONFIG_LED_STATUS
1016 Several configurations allow to display the current
1017 status using a LED. For instance, the LED will blink
1018 fast while running U-Boot code, stop blinking as
1019 soon as a reply to a BOOTP request was received, and
1020 start blinking slow once the Linux kernel is running
1021 (supported by a status LED driver in the Linux
1022 kernel). Defining CONFIG_LED_STATUS enables this
1027 CONFIG_LED_STATUS_GPIO
1028 The status LED can be connected to a GPIO pin.
1029 In such cases, the gpio_led driver can be used as a
1030 status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
1031 to include the gpio_led driver in the U-Boot binary.
1033 CONFIG_GPIO_LED_INVERTED_TABLE
1034 Some GPIO connected LEDs may have inverted polarity in which
1035 case the GPIO high value corresponds to LED off state and
1036 GPIO low value corresponds to LED on state.
1037 In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
1038 with a list of GPIO LEDs that have inverted polarity.
1041 CONFIG_SYS_NUM_I2C_BUSES
1042 Hold the number of i2c buses you want to use.
1044 CONFIG_SYS_I2C_DIRECT_BUS
1045 define this, if you don't use i2c muxes on your hardware.
1046 if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
1049 CONFIG_SYS_I2C_MAX_HOPS
1050 define how many muxes are maximal consecutively connected
1051 on one i2c bus. If you not use i2c muxes, omit this
1054 CONFIG_SYS_I2C_BUSES
1055 hold a list of buses you want to use, only used if
1056 CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
1057 a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
1058 CONFIG_SYS_NUM_I2C_BUSES = 9:
1060 CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
1061 {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
1062 {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
1063 {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
1064 {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
1065 {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
1066 {1, {I2C_NULL_HOP}}, \
1067 {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
1068 {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
1072 bus 0 on adapter 0 without a mux
1073 bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
1074 bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
1075 bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
1076 bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
1077 bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
1078 bus 6 on adapter 1 without a mux
1079 bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
1080 bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
1082 If you do not have i2c muxes on your board, omit this define.
1084 - Legacy I2C Support:
1085 If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
1086 then the following macros need to be defined (examples are
1087 from include/configs/lwmon.h):
1091 (Optional). Any commands necessary to enable the I2C
1092 controller or configure ports.
1094 eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
1098 The code necessary to make the I2C data line active
1099 (driven). If the data line is open collector, this
1102 eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
1106 The code necessary to make the I2C data line tri-stated
1107 (inactive). If the data line is open collector, this
1110 eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
1114 Code that returns true if the I2C data line is high,
1117 eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
1121 If <bit> is true, sets the I2C data line high. If it
1122 is false, it clears it (low).
1124 eg: #define I2C_SDA(bit) \
1125 if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
1126 else immr->im_cpm.cp_pbdat &= ~PB_SDA
1130 If <bit> is true, sets the I2C clock line high. If it
1131 is false, it clears it (low).
1133 eg: #define I2C_SCL(bit) \
1134 if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
1135 else immr->im_cpm.cp_pbdat &= ~PB_SCL
1139 This delay is invoked four times per clock cycle so this
1140 controls the rate of data transfer. The data rate thus
1141 is 1 / (I2C_DELAY * 4). Often defined to be something
1144 #define I2C_DELAY udelay(2)
1146 CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
1148 If your arch supports the generic GPIO framework (asm/gpio.h),
1149 then you may alternatively define the two GPIOs that are to be
1150 used as SCL / SDA. Any of the previous I2C_xxx macros will
1151 have GPIO-based defaults assigned to them as appropriate.
1153 You should define these to the GPIO value as given directly to
1154 the generic GPIO functions.
1156 CONFIG_SYS_I2C_INIT_BOARD
1158 When a board is reset during an i2c bus transfer
1159 chips might think that the current transfer is still
1160 in progress. On some boards it is possible to access
1161 the i2c SCLK line directly, either by using the
1162 processor pin as a GPIO or by having a second pin
1163 connected to the bus. If this option is defined a
1164 custom i2c_init_board() routine in boards/xxx/board.c
1165 is run early in the boot sequence.
1167 CONFIG_I2C_MULTI_BUS
1169 This option allows the use of multiple I2C buses, each of which
1170 must have a controller. At any point in time, only one bus is
1171 active. To switch to a different bus, use the 'i2c dev' command.
1172 Note that bus numbering is zero-based.
1174 CONFIG_SYS_I2C_NOPROBES
1176 This option specifies a list of I2C devices that will be skipped
1177 when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
1178 is set, specify a list of bus-device pairs. Otherwise, specify
1179 a 1D array of device addresses
1182 #undef CONFIG_I2C_MULTI_BUS
1183 #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
1185 will skip addresses 0x50 and 0x68 on a board with one I2C bus
1187 #define CONFIG_I2C_MULTI_BUS
1188 #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
1190 will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
1192 CONFIG_SYS_RTC_BUS_NUM
1194 If defined, then this indicates the I2C bus number for the RTC.
1195 If not defined, then U-Boot assumes that RTC is on I2C bus 0.
1197 CONFIG_SOFT_I2C_READ_REPEATED_START
1199 defining this will force the i2c_read() function in
1200 the soft_i2c driver to perform an I2C repeated start
1201 between writing the address pointer and reading the
1202 data. If this define is omitted the default behaviour
1203 of doing a stop-start sequence will be used. Most I2C
1204 devices can use either method, but some require one or
1207 - SPI Support: CONFIG_SPI
1209 Enables SPI driver (so far only tested with
1210 SPI EEPROM, also an instance works with Crystal A/D and
1211 D/As on the SACSng board)
1213 CONFIG_SYS_SPI_MXC_WAIT
1214 Timeout for waiting until spi transfer completed.
1215 default: (CONFIG_SYS_HZ/100) /* 10 ms */
1217 - FPGA Support: CONFIG_FPGA
1219 Enables FPGA subsystem.
1221 CONFIG_FPGA_<vendor>
1223 Enables support for specific chip vendors.
1226 CONFIG_FPGA_<family>
1228 Enables support for FPGA family.
1229 (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
1231 CONFIG_SYS_FPGA_CHECK_BUSY
1233 Enable checks on FPGA configuration interface busy
1234 status by the configuration function. This option
1235 will require a board or device specific function to
1240 If defined, a function that provides delays in the FPGA
1241 configuration driver.
1243 CONFIG_SYS_FPGA_CHECK_ERROR
1245 Check for configuration errors during FPGA bitfile
1246 loading. For example, abort during Virtex II
1247 configuration if the INIT_B line goes low (which
1248 indicated a CRC error).
1250 CONFIG_SYS_FPGA_WAIT_INIT
1252 Maximum time to wait for the INIT_B line to de-assert
1253 after PROB_B has been de-asserted during a Virtex II
1254 FPGA configuration sequence. The default time is 500
1257 CONFIG_SYS_FPGA_WAIT_BUSY
1259 Maximum time to wait for BUSY to de-assert during
1260 Virtex II FPGA configuration. The default is 5 ms.
1262 CONFIG_SYS_FPGA_WAIT_CONFIG
1264 Time to wait after FPGA configuration. The default is
1267 - Vendor Parameter Protection:
1269 U-Boot considers the values of the environment
1270 variables "serial#" (Board Serial Number) and
1271 "ethaddr" (Ethernet Address) to be parameters that
1272 are set once by the board vendor / manufacturer, and
1273 protects these variables from casual modification by
1274 the user. Once set, these variables are read-only,
1275 and write or delete attempts are rejected. You can
1276 change this behaviour:
1278 If CONFIG_ENV_OVERWRITE is #defined in your config
1279 file, the write protection for vendor parameters is
1280 completely disabled. Anybody can change or delete
1283 Alternatively, if you define _both_ an ethaddr in the
1284 default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
1285 Ethernet address is installed in the environment,
1286 which can be changed exactly ONCE by the user. [The
1287 serial# is unaffected by this, i. e. it remains
1290 The same can be accomplished in a more flexible way
1291 for any variable by configuring the type of access
1292 to allow for those variables in the ".flags" variable
1293 or define CONFIG_ENV_FLAGS_LIST_STATIC.
1298 Define this variable to enable the reservation of
1299 "protected RAM", i. e. RAM which is not overwritten
1300 by U-Boot. Define CONFIG_PRAM to hold the number of
1301 kB you want to reserve for pRAM. You can overwrite
1302 this default value by defining an environment
1303 variable "pram" to the number of kB you want to
1304 reserve. Note that the board info structure will
1305 still show the full amount of RAM. If pRAM is
1306 reserved, a new environment variable "mem" will
1307 automatically be defined to hold the amount of
1308 remaining RAM in a form that can be passed as boot
1309 argument to Linux, for instance like that:
1311 setenv bootargs ... mem=\${mem}
1314 This way you can tell Linux not to use this memory,
1315 either, which results in a memory region that will
1316 not be affected by reboots.
1318 *WARNING* If your board configuration uses automatic
1319 detection of the RAM size, you must make sure that
1320 this memory test is non-destructive. So far, the
1321 following board configurations are known to be
1324 IVMS8, IVML24, SPD8xx,
1325 HERMES, IP860, RPXlite, LWMON,
1331 In the current implementation, the local variables
1332 space and global environment variables space are
1333 separated. Local variables are those you define by
1334 simply typing `name=value'. To access a local
1335 variable later on, you have write `$name' or
1336 `${name}'; to execute the contents of a variable
1337 directly type `$name' at the command prompt.
1339 Global environment variables are those you use
1340 setenv/printenv to work with. To run a command stored
1341 in such a variable, you need to use the run command,
1342 and you must not use the '$' sign to access them.
1344 To store commands and special characters in a
1345 variable, please use double quotation marks
1346 surrounding the whole text of the variable, instead
1347 of the backslashes before semicolons and special
1350 - Default Environment:
1351 CONFIG_EXTRA_ENV_SETTINGS
1353 Define this to contain any number of null terminated
1354 strings (variable = value pairs) that will be part of
1355 the default environment compiled into the boot image.
1357 For example, place something like this in your
1358 board's config file:
1360 #define CONFIG_EXTRA_ENV_SETTINGS \
1364 Warning: This method is based on knowledge about the
1365 internal format how the environment is stored by the
1366 U-Boot code. This is NOT an official, exported
1367 interface! Although it is unlikely that this format
1368 will change soon, there is no guarantee either.
1369 You better know what you are doing here.
1371 Note: overly (ab)use of the default environment is
1372 discouraged. Make sure to check other ways to preset
1373 the environment like the "source" command or the
1376 CONFIG_DELAY_ENVIRONMENT
1378 Normally the environment is loaded when the board is
1379 initialised so that it is available to U-Boot. This inhibits
1380 that so that the environment is not available until
1381 explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
1382 this is instead controlled by the value of
1383 /config/load-environment.
1385 CONFIG_STANDALONE_LOAD_ADDR
1387 This option defines a board specific value for the
1388 address where standalone program gets loaded, thus
1389 overwriting the architecture dependent default
1392 - Automatic software updates via TFTP server
1394 CONFIG_UPDATE_TFTP_CNT_MAX
1395 CONFIG_UPDATE_TFTP_MSEC_MAX
1397 These options enable and control the auto-update feature;
1398 for a more detailed description refer to doc/README.update.
1400 - MTD Support (mtdparts command, UBI support)
1401 CONFIG_MTD_UBI_WL_THRESHOLD
1402 This parameter defines the maximum difference between the highest
1403 erase counter value and the lowest erase counter value of eraseblocks
1404 of UBI devices. When this threshold is exceeded, UBI starts performing
1405 wear leveling by means of moving data from eraseblock with low erase
1406 counter to eraseblocks with high erase counter.
1408 The default value should be OK for SLC NAND flashes, NOR flashes and
1409 other flashes which have eraseblock life-cycle 100000 or more.
1410 However, in case of MLC NAND flashes which typically have eraseblock
1411 life-cycle less than 10000, the threshold should be lessened (e.g.,
1412 to 128 or 256, although it does not have to be power of 2).
1416 CONFIG_MTD_UBI_BEB_LIMIT
1417 This option specifies the maximum bad physical eraseblocks UBI
1418 expects on the MTD device (per 1024 eraseblocks). If the
1419 underlying flash does not admit of bad eraseblocks (e.g. NOR
1420 flash), this value is ignored.
1422 NAND datasheets often specify the minimum and maximum NVM
1423 (Number of Valid Blocks) for the flashes' endurance lifetime.
1424 The maximum expected bad eraseblocks per 1024 eraseblocks
1425 then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
1426 which gives 20 for most NANDs (MaxNVB is basically the total
1427 count of eraseblocks on the chip).
1429 To put it differently, if this value is 20, UBI will try to
1430 reserve about 1.9% of physical eraseblocks for bad blocks
1431 handling. And that will be 1.9% of eraseblocks on the entire
1432 NAND chip, not just the MTD partition UBI attaches. This means
1433 that if you have, say, a NAND flash chip admits maximum 40 bad
1434 eraseblocks, and it is split on two MTD partitions of the same
1435 size, UBI will reserve 40 eraseblocks when attaching a
1440 CONFIG_MTD_UBI_FASTMAP
1441 Fastmap is a mechanism which allows attaching an UBI device
1442 in nearly constant time. Instead of scanning the whole MTD device it
1443 only has to locate a checkpoint (called fastmap) on the device.
1444 The on-flash fastmap contains all information needed to attach
1445 the device. Using fastmap makes only sense on large devices where
1446 attaching by scanning takes long. UBI will not automatically install
1447 a fastmap on old images, but you can set the UBI parameter
1448 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
1449 that fastmap-enabled images are still usable with UBI implementations
1450 without fastmap support. On typical flash devices the whole fastmap
1451 fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
1453 CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
1454 Set this parameter to enable fastmap automatically on images
1458 CONFIG_MTD_UBI_FM_DEBUG
1459 Enable UBI fastmap debug
1464 Enable building of SPL globally.
1466 CONFIG_SPL_PANIC_ON_RAW_IMAGE
1467 When defined, SPL will panic() if the image it has
1468 loaded does not have a signature.
1469 Defining this is useful when code which loads images
1470 in SPL cannot guarantee that absolutely all read errors
1472 An example is the LPC32XX MLC NAND driver, which will
1473 consider that a completely unreadable NAND block is bad,
1474 and thus should be skipped silently.
1476 CONFIG_SPL_DISPLAY_PRINT
1477 For ARM, enable an optional function to print more information
1478 about the running system.
1480 CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
1481 Set this for NAND SPL on PPC mpc83xx targets, so that
1482 start.S waits for the rest of the SPL to load before
1483 continuing (the hardware starts execution after just
1484 loading the first page rather than the full 4K).
1487 Support for a lightweight UBI (fastmap) scanner and
1490 CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
1491 CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
1492 CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
1493 CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
1494 CONFIG_SYS_NAND_ECCBYTES
1495 Defines the size and behavior of the NAND that SPL uses
1498 CONFIG_SYS_NAND_U_BOOT_DST
1499 Location in memory to load U-Boot to
1501 CONFIG_SYS_NAND_U_BOOT_SIZE
1502 Size of image to load
1504 CONFIG_SYS_NAND_U_BOOT_START
1505 Entry point in loaded image to jump to
1507 CONFIG_SYS_NAND_HW_ECC_OOBFIRST
1508 Define this if you need to first read the OOB and then the
1509 data. This is used, for example, on davinci platforms.
1511 CONFIG_SPL_RAM_DEVICE
1512 Support for running image already present in ram, in SPL binary
1514 CONFIG_SPL_FIT_PRINT
1515 Printing information about a FIT image adds quite a bit of
1516 code to SPL. So this is normally disabled in SPL. Use this
1517 option to re-enable it. This will affect the output of the
1518 bootm command when booting a FIT image.
1520 - Interrupt support (PPC):
1522 There are common interrupt_init() and timer_interrupt()
1523 for all PPC archs. interrupt_init() calls interrupt_init_cpu()
1524 for CPU specific initialization. interrupt_init_cpu()
1525 should set decrementer_count to appropriate value. If
1526 CPU resets decrementer automatically after interrupt
1527 (ppc4xx) it should set decrementer_count to zero.
1528 timer_interrupt() calls timer_interrupt_cpu() for CPU
1529 specific handling. If board has watchdog / status_led
1530 / other_activity_monitor it works automatically from
1531 general timer_interrupt().
1534 Board initialization settings:
1535 ------------------------------
1537 During Initialization u-boot calls a number of board specific functions
1538 to allow the preparation of board specific prerequisites, e.g. pin setup
1539 before drivers are initialized. To enable these callbacks the
1540 following configuration macros have to be defined. Currently this is
1541 architecture specific, so please check arch/your_architecture/lib/board.c
1542 typically in board_init_f() and board_init_r().
1544 - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
1545 - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
1546 - CONFIG_BOARD_LATE_INIT: Call board_late_init()
1548 Configuration Settings:
1549 -----------------------
1551 - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
1552 Optionally it can be defined to support 64-bit memory commands.
1554 - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
1555 undefine this when you're short of memory.
1557 - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
1558 width of the commands listed in the 'help' command output.
1560 - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
1561 prompt for user input.
1563 - CONFIG_SYS_BAUDRATE_TABLE:
1564 List of legal baudrate settings for this board.
1566 - CONFIG_SYS_MEM_RESERVE_SECURE
1567 Only implemented for ARMv8 for now.
1568 If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
1569 is substracted from total RAM and won't be reported to OS.
1570 This memory can be used as secure memory. A variable
1571 gd->arch.secure_ram is used to track the location. In systems
1572 the RAM base is not zero, or RAM is divided into banks,
1573 this variable needs to be recalcuated to get the address.
1575 - CONFIG_SYS_LOADS_BAUD_CHANGE:
1576 Enable temporary baudrate change while serial download
1578 - CONFIG_SYS_SDRAM_BASE:
1579 Physical start address of SDRAM. _Must_ be 0 here.
1581 - CONFIG_SYS_FLASH_BASE:
1582 Physical start address of Flash memory.
1584 - CONFIG_SYS_MONITOR_LEN:
1585 Size of memory reserved for monitor code, used to
1586 determine _at_compile_time_ (!) if the environment is
1587 embedded within the U-Boot image, or in a separate
1590 - CONFIG_SYS_MALLOC_LEN:
1591 Size of DRAM reserved for malloc() use.
1593 - CONFIG_SYS_MALLOC_F_LEN
1594 Size of the malloc() pool for use before relocation. If
1595 this is defined, then a very simple malloc() implementation
1596 will become available before relocation. The address is just
1597 below the global data, and the stack is moved down to make
1600 This feature allocates regions with increasing addresses
1601 within the region. calloc() is supported, but realloc()
1602 is not available. free() is supported but does nothing.
1603 The memory will be freed (or in fact just forgotten) when
1604 U-Boot relocates itself.
1606 - CONFIG_SYS_MALLOC_SIMPLE
1607 Provides a simple and small malloc() and calloc() for those
1608 boards which do not use the full malloc in SPL (which is
1609 enabled with CONFIG_SYS_SPL_MALLOC).
1611 - CONFIG_SYS_NONCACHED_MEMORY:
1612 Size of non-cached memory area. This area of memory will be
1613 typically located right below the malloc() area and mapped
1614 uncached in the MMU. This is useful for drivers that would
1615 otherwise require a lot of explicit cache maintenance. For
1616 some drivers it's also impossible to properly maintain the
1617 cache. For example if the regions that need to be flushed
1618 are not a multiple of the cache-line size, *and* padding
1619 cannot be allocated between the regions to align them (i.e.
1620 if the HW requires a contiguous array of regions, and the
1621 size of each region is not cache-aligned), then a flush of
1622 one region may result in overwriting data that hardware has
1623 written to another region in the same cache-line. This can
1624 happen for example in network drivers where descriptors for
1625 buffers are typically smaller than the CPU cache-line (e.g.
1626 16 bytes vs. 32 or 64 bytes).
1628 Non-cached memory is only supported on 32-bit ARM at present.
1630 - CONFIG_SYS_BOOTMAPSZ:
1631 Maximum size of memory mapped by the startup code of
1632 the Linux kernel; all data that must be processed by
1633 the Linux kernel (bd_info, boot arguments, FDT blob if
1634 used) must be put below this limit, unless "bootm_low"
1635 environment variable is defined and non-zero. In such case
1636 all data for the Linux kernel must be between "bootm_low"
1637 and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
1638 variable "bootm_mapsize" will override the value of
1639 CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
1640 then the value in "bootm_size" will be used instead.
1642 - CONFIG_SYS_BOOT_GET_CMDLINE:
1643 Enables allocating and saving kernel cmdline in space between
1644 "bootm_low" and "bootm_low" + BOOTMAPSZ.
1646 - CONFIG_SYS_BOOT_GET_KBD:
1647 Enables allocating and saving a kernel copy of the bd_info in
1648 space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
1650 - CONFIG_SYS_FLASH_PROTECTION
1651 If defined, hardware flash sectors protection is used
1652 instead of U-Boot software protection.
1654 - CONFIG_SYS_FLASH_CFI:
1655 Define if the flash driver uses extra elements in the
1656 common flash structure for storing flash geometry.
1658 - CONFIG_FLASH_CFI_DRIVER
1659 This option also enables the building of the cfi_flash driver
1660 in the drivers directory
1662 - CONFIG_FLASH_CFI_MTD
1663 This option enables the building of the cfi_mtd driver
1664 in the drivers directory. The driver exports CFI flash
1667 - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
1668 Use buffered writes to flash.
1670 - CONFIG_FLASH_SPANSION_S29WS_N
1671 s29ws-n MirrorBit flash has non-standard addresses for buffered
1674 - CONFIG_FLASH_SHOW_PROGRESS
1675 If defined (must be an integer), print out countdown
1676 digits and dots. Recommended value: 45 (9..1) for 80
1677 column displays, 15 (3..1) for 40 column displays.
1679 - CONFIG_FLASH_VERIFY
1680 If defined, the content of the flash (destination) is compared
1681 against the source after the write operation. An error message
1682 will be printed when the contents are not identical.
1683 Please note that this option is useless in nearly all cases,
1684 since such flash programming errors usually are detected earlier
1685 while unprotecting/erasing/programming. Please only enable
1686 this option if you really know what you are doing.
1688 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1689 - CONFIG_ENV_FLAGS_LIST_STATIC
1690 Enable validation of the values given to environment variables when
1691 calling env set. Variables can be restricted to only decimal,
1692 hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
1693 the variables can also be restricted to IP address or MAC address.
1695 The format of the list is:
1696 type_attribute = [s|d|x|b|i|m]
1697 access_attribute = [a|r|o|c]
1698 attributes = type_attribute[access_attribute]
1699 entry = variable_name[:attributes]
1702 The type attributes are:
1703 s - String (default)
1706 b - Boolean ([1yYtT|0nNfF])
1710 The access attributes are:
1716 - CONFIG_ENV_FLAGS_LIST_DEFAULT
1717 Define this to a list (string) to define the ".flags"
1718 environment variable in the default or embedded environment.
1720 - CONFIG_ENV_FLAGS_LIST_STATIC
1721 Define this to a list (string) to define validation that
1722 should be done if an entry is not found in the ".flags"
1723 environment variable. To override a setting in the static
1724 list, simply add an entry for the same variable name to the
1727 If CONFIG_REGEX is defined, the variable_name above is evaluated as a
1728 regular expression. This allows multiple variables to define the same
1729 flags without explicitly listing them for each variable.
1731 The following definitions that deal with the placement and management
1732 of environment data (variable area); in general, we support the
1733 following configurations:
1735 - CONFIG_BUILD_ENVCRC:
1737 Builds up envcrc with the target environment so that external utils
1738 may easily extract it and embed it in final U-Boot images.
1740 BE CAREFUL! The first access to the environment happens quite early
1741 in U-Boot initialization (when we try to get the setting of for the
1742 console baudrate). You *MUST* have mapped your NVRAM area then, or
1745 Please note that even with NVRAM we still use a copy of the
1746 environment in RAM: we could work on NVRAM directly, but we want to
1747 keep settings there always unmodified except somebody uses "saveenv"
1748 to save the current settings.
1750 BE CAREFUL! For some special cases, the local device can not use
1751 "saveenv" command. For example, the local device will get the
1752 environment stored in a remote NOR flash by SRIO or PCIE link,
1753 but it can not erase, write this NOR flash by SRIO or PCIE interface.
1755 - CONFIG_NAND_ENV_DST
1757 Defines address in RAM to which the nand_spl code should copy the
1758 environment. If redundant environment is used, it will be copied to
1759 CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
1761 Please note that the environment is read-only until the monitor
1762 has been relocated to RAM and a RAM copy of the environment has been
1763 created; also, when using EEPROM you will have to use env_get_f()
1764 until then to read environment variables.
1766 The environment is protected by a CRC32 checksum. Before the monitor
1767 is relocated into RAM, as a result of a bad CRC you will be working
1768 with the compiled-in default environment - *silently*!!! [This is
1769 necessary, because the first environment variable we need is the
1770 "baudrate" setting for the console - if we have a bad CRC, we don't
1771 have any device yet where we could complain.]
1773 Note: once the monitor has been relocated, then it will complain if
1774 the default environment is used; a new CRC is computed as soon as you
1775 use the "saveenv" command to store a valid environment.
1777 - CONFIG_SYS_FAULT_MII_ADDR:
1778 MII address of the PHY to check for the Ethernet link state.
1780 - CONFIG_NS16550_MIN_FUNCTIONS:
1781 Define this if you desire to only have use of the NS16550_init
1782 and NS16550_putc functions for the serial driver located at
1783 drivers/serial/ns16550.c. This option is useful for saving
1784 space for already greatly restricted images, including but not
1785 limited to NAND_SPL configurations.
1787 - CONFIG_DISPLAY_BOARDINFO
1788 Display information about the board that U-Boot is running on
1789 when U-Boot starts up. The board function checkboard() is called
1792 - CONFIG_DISPLAY_BOARDINFO_LATE
1793 Similar to the previous option, but display this information
1794 later, once stdio is running and output goes to the LCD, if
1797 Low Level (hardware related) configuration options:
1798 ---------------------------------------------------
1800 - CONFIG_SYS_CACHELINE_SIZE:
1801 Cache Line Size of the CPU.
1803 - CONFIG_SYS_CCSRBAR_DEFAULT:
1804 Default (power-on reset) physical address of CCSR on Freescale
1807 - CONFIG_SYS_CCSRBAR:
1808 Virtual address of CCSR. On a 32-bit build, this is typically
1809 the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
1811 - CONFIG_SYS_CCSRBAR_PHYS:
1812 Physical address of CCSR. CCSR can be relocated to a new
1813 physical address, if desired. In this case, this macro should
1814 be set to that address. Otherwise, it should be set to the
1815 same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
1816 is typically relocated on 36-bit builds. It is recommended
1817 that this macro be defined via the _HIGH and _LOW macros:
1819 #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
1820 * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
1822 - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
1823 Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
1824 either 0 (32-bit build) or 0xF (36-bit build). This macro is
1825 used in assembly code, so it must not contain typecasts or
1826 integer size suffixes (e.g. "ULL").
1828 - CONFIG_SYS_CCSRBAR_PHYS_LOW:
1829 Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
1830 used in assembly code, so it must not contain typecasts or
1831 integer size suffixes (e.g. "ULL").
1833 - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
1834 DO NOT CHANGE unless you know exactly what you're
1835 doing! (11-4) [MPC8xx systems only]
1837 - CONFIG_SYS_INIT_RAM_ADDR:
1839 Start address of memory area that can be used for
1840 initial data and stack; please note that this must be
1841 writable memory that is working WITHOUT special
1842 initialization, i. e. you CANNOT use normal RAM which
1843 will become available only after programming the
1844 memory controller and running certain initialization
1847 U-Boot uses the following memory types:
1848 - MPC8xx: IMMR (internal memory of the CPU)
1850 - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
1852 - CONFIG_SYS_OR_TIMING_SDRAM:
1855 - CONFIG_SYS_MAMR_PTA:
1856 periodic timer for refresh
1859 Chip has SRIO or not
1862 Board has SRIO 1 port available
1865 Board has SRIO 2 port available
1867 - CONFIG_SRIO_PCIE_BOOT_MASTER
1868 Board can support master function for Boot from SRIO and PCIE
1870 - CONFIG_SYS_SRIOn_MEM_VIRT:
1871 Virtual Address of SRIO port 'n' memory region
1873 - CONFIG_SYS_SRIOn_MEM_PHYxS:
1874 Physical Address of SRIO port 'n' memory region
1876 - CONFIG_SYS_SRIOn_MEM_SIZE:
1877 Size of SRIO port 'n' memory region
1879 - CONFIG_SYS_NAND_BUSWIDTH_16BIT
1880 Defined to tell the NAND controller that the NAND chip is using
1882 Not all NAND drivers use this symbol.
1883 Example of drivers that use it:
1884 - drivers/mtd/nand/raw/ndfc.c
1885 - drivers/mtd/nand/raw/mxc_nand.c
1887 - CONFIG_SYS_NDFC_EBC0_CFG
1888 Sets the EBC0_CFG register for the NDFC. If not defined
1889 a default value will be used.
1892 Get DDR timing information from an I2C EEPROM. Common
1893 with pluggable memory modules such as SODIMMs
1896 I2C address of the SPD EEPROM
1898 - CONFIG_SYS_SPD_BUS_NUM
1899 If SPD EEPROM is on an I2C bus other than the first
1900 one, specify here. Note that the value must resolve
1901 to something your driver can deal with.
1903 - CONFIG_FSL_DDR_INTERACTIVE
1904 Enable interactive DDR debugging. See doc/README.fsl-ddr.
1906 - CONFIG_FSL_DDR_SYNC_REFRESH
1907 Enable sync of refresh for multiple controllers.
1909 - CONFIG_FSL_DDR_BIST
1910 Enable built-in memory test for Freescale DDR controllers.
1913 Enable RMII mode for all FECs.
1914 Note that this is a global option, we can't
1915 have one FEC in standard MII mode and another in RMII mode.
1917 - CONFIG_CRC32_VERIFY
1918 Add a verify option to the crc32 command.
1921 => crc32 -v <address> <count> <crc32>
1923 Where address/count indicate a memory area
1924 and crc32 is the correct crc32 which the
1928 Add the "loopw" memory command. This only takes effect if
1929 the memory commands are activated globally (CONFIG_CMD_MEMORY).
1931 - CONFIG_CMD_MX_CYCLIC
1932 Add the "mdc" and "mwc" memory commands. These are cyclic
1937 This command will print 4 bytes (10,11,12,13) each 500 ms.
1939 => mwc.l 100 12345678 10
1940 This command will write 12345678 to address 100 all 10 ms.
1942 This only takes effect if the memory commands are activated
1943 globally (CONFIG_CMD_MEMORY).
1946 Set when the currently-running compilation is for an artifact
1947 that will end up in the SPL (as opposed to the TPL or U-Boot
1948 proper). Code that needs stage-specific behavior should check
1952 Set when the currently-running compilation is for an artifact
1953 that will end up in the TPL (as opposed to the SPL or U-Boot
1954 proper). Code that needs stage-specific behavior should check
1957 - CONFIG_ARCH_MAP_SYSMEM
1958 Generally U-Boot (and in particular the md command) uses
1959 effective address. It is therefore not necessary to regard
1960 U-Boot address as virtual addresses that need to be translated
1961 to physical addresses. However, sandbox requires this, since
1962 it maintains its own little RAM buffer which contains all
1963 addressable memory. This option causes some memory accesses
1964 to be mapped through map_sysmem() / unmap_sysmem().
1966 - CONFIG_X86_RESET_VECTOR
1967 If defined, the x86 reset vector code is included. This is not
1968 needed when U-Boot is running from Coreboot.
1970 - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
1971 Option to disable subpage write in NAND driver
1972 driver that uses this:
1973 drivers/mtd/nand/raw/davinci_nand.c
1975 Freescale QE/FMAN Firmware Support:
1976 -----------------------------------
1978 The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
1979 loading of "firmware", which is encoded in the QE firmware binary format.
1980 This firmware often needs to be loaded during U-Boot booting, so macros
1981 are used to identify the storage device (NOR flash, SPI, etc) and the address
1984 - CONFIG_SYS_FMAN_FW_ADDR
1985 The address in the storage device where the FMAN microcode is located. The
1986 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
1989 - CONFIG_SYS_QE_FW_ADDR
1990 The address in the storage device where the QE microcode is located. The
1991 meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
1994 - CONFIG_SYS_QE_FMAN_FW_LENGTH
1995 The maximum possible size of the firmware. The firmware binary format
1996 has a field that specifies the actual size of the firmware, but it
1997 might not be possible to read any part of the firmware unless some
1998 local storage is allocated to hold the entire firmware first.
2000 - CONFIG_SYS_QE_FMAN_FW_IN_NOR
2001 Specifies that QE/FMAN firmware is located in NOR flash, mapped as
2002 normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
2003 virtual address in NOR flash.
2005 - CONFIG_SYS_QE_FMAN_FW_IN_NAND
2006 Specifies that QE/FMAN firmware is located in NAND flash.
2007 CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
2009 - CONFIG_SYS_QE_FMAN_FW_IN_MMC
2010 Specifies that QE/FMAN firmware is located on the primary SD/MMC
2011 device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
2013 - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
2014 Specifies that QE/FMAN firmware is located in the remote (master)
2015 memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
2016 can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
2017 window->master inbound window->master LAW->the ucode address in
2018 master's memory space.
2020 Freescale Layerscape Management Complex Firmware Support:
2021 ---------------------------------------------------------
2022 The Freescale Layerscape Management Complex (MC) supports the loading of
2024 This firmware often needs to be loaded during U-Boot booting, so macros
2025 are used to identify the storage device (NOR flash, SPI, etc) and the address
2028 - CONFIG_FSL_MC_ENET
2029 Enable the MC driver for Layerscape SoCs.
2031 Freescale Layerscape Debug Server Support:
2032 -------------------------------------------
2033 The Freescale Layerscape Debug Server Support supports the loading of
2034 "Debug Server firmware" and triggering SP boot-rom.
2035 This firmware often needs to be loaded during U-Boot booting.
2037 - CONFIG_SYS_MC_RSV_MEM_ALIGN
2038 Define alignment of reserved memory MC requires
2043 In order to achieve reproducible builds, timestamps used in the U-Boot build
2044 process have to be set to a fixed value.
2046 This is done using the SOURCE_DATE_EPOCH environment variable.
2047 SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
2048 option for U-Boot or an environment variable in U-Boot.
2050 SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
2052 Building the Software:
2053 ======================
2055 Building U-Boot has been tested in several native build environments
2056 and in many different cross environments. Of course we cannot support
2057 all possibly existing versions of cross development tools in all
2058 (potentially obsolete) versions. In case of tool chain problems we
2059 recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
2060 which is extensively used to build and test U-Boot.
2062 If you are not using a native environment, it is assumed that you
2063 have GNU cross compiling tools available in your path. In this case,
2064 you must set the environment variable CROSS_COMPILE in your shell.
2065 Note that no changes to the Makefile or any other source files are
2066 necessary. For example using the ELDK on a 4xx CPU, please enter:
2068 $ CROSS_COMPILE=ppc_4xx-
2069 $ export CROSS_COMPILE
2071 U-Boot is intended to be simple to build. After installing the
2072 sources you must configure U-Boot for one specific board type. This
2077 where "NAME_defconfig" is the name of one of the existing configu-
2078 rations; see configs/*_defconfig for supported names.
2080 Note: for some boards special configuration names may exist; check if
2081 additional information is available from the board vendor; for
2082 instance, the TQM823L systems are available without (standard)
2083 or with LCD support. You can select such additional "features"
2084 when choosing the configuration, i. e.
2086 make TQM823L_defconfig
2087 - will configure for a plain TQM823L, i. e. no LCD support
2089 make TQM823L_LCD_defconfig
2090 - will configure for a TQM823L with U-Boot console on LCD
2095 Finally, type "make all", and you should get some working U-Boot
2096 images ready for download to / installation on your system:
2098 - "u-boot.bin" is a raw binary image
2099 - "u-boot" is an image in ELF binary format
2100 - "u-boot.srec" is in Motorola S-Record format
2102 By default the build is performed locally and the objects are saved
2103 in the source directory. One of the two methods can be used to change
2104 this behavior and build U-Boot to some external directory:
2106 1. Add O= to the make command line invocations:
2108 make O=/tmp/build distclean
2109 make O=/tmp/build NAME_defconfig
2110 make O=/tmp/build all
2112 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
2114 export KBUILD_OUTPUT=/tmp/build
2119 Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
2122 User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
2123 setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
2124 For example to treat all compiler warnings as errors:
2126 make KCFLAGS=-Werror
2128 Please be aware that the Makefiles assume you are using GNU make, so
2129 for instance on NetBSD you might need to use "gmake" instead of
2133 If the system board that you have is not listed, then you will need
2134 to port U-Boot to your hardware platform. To do this, follow these
2137 1. Create a new directory to hold your board specific code. Add any
2138 files you need. In your board directory, you will need at least
2139 the "Makefile" and a "<board>.c".
2140 2. Create a new configuration file "include/configs/<board>.h" for
2142 3. If you're porting U-Boot to a new CPU, then also create a new
2143 directory to hold your CPU specific code. Add any files you need.
2144 4. Run "make <board>_defconfig" with your new name.
2145 5. Type "make", and you should get a working "u-boot.srec" file
2146 to be installed on your target system.
2147 6. Debug and solve any problems that might arise.
2148 [Of course, this last step is much harder than it sounds.]
2151 Testing of U-Boot Modifications, Ports to New Hardware, etc.:
2152 ==============================================================
2154 If you have modified U-Boot sources (for instance added a new board
2155 or support for new devices, a new CPU, etc.) you are expected to
2156 provide feedback to the other developers. The feedback normally takes
2157 the form of a "patch", i.e. a context diff against a certain (latest
2158 official or latest in the git repository) version of U-Boot sources.
2160 But before you submit such a patch, please verify that your modifi-
2161 cation did not break existing code. At least make sure that *ALL* of
2162 the supported boards compile WITHOUT ANY compiler warnings. To do so,
2163 just run the buildman script (tools/buildman/buildman), which will
2164 configure and build U-Boot for ALL supported system. Be warned, this
2165 will take a while. Please see the buildman README, or run 'buildman -H'
2169 See also "U-Boot Porting Guide" below.
2172 Monitor Commands - Overview:
2173 ============================
2175 go - start application at address 'addr'
2176 run - run commands in an environment variable
2177 bootm - boot application image from memory
2178 bootp - boot image via network using BootP/TFTP protocol
2179 bootz - boot zImage from memory
2180 tftpboot- boot image via network using TFTP protocol
2181 and env variables "ipaddr" and "serverip"
2182 (and eventually "gatewayip")
2183 tftpput - upload a file via network using TFTP protocol
2184 rarpboot- boot image via network using RARP/TFTP protocol
2185 diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
2186 loads - load S-Record file over serial line
2187 loadb - load binary file over serial line (kermit mode)
2188 loadm - load binary blob from source address to destination address
2190 mm - memory modify (auto-incrementing)
2191 nm - memory modify (constant address)
2192 mw - memory write (fill)
2195 cmp - memory compare
2196 crc32 - checksum calculation
2197 i2c - I2C sub-system
2198 sspi - SPI utility commands
2199 base - print or set address offset
2200 printenv- print environment variables
2201 pwm - control pwm channels
2202 setenv - set environment variables
2203 saveenv - save environment variables to persistent storage
2204 protect - enable or disable FLASH write protection
2205 erase - erase FLASH memory
2206 flinfo - print FLASH memory information
2207 nand - NAND memory operations (see doc/README.nand)
2208 bdinfo - print Board Info structure
2209 iminfo - print header information for application image
2210 coninfo - print console devices and informations
2211 ide - IDE sub-system
2212 loop - infinite loop on address range
2213 loopw - infinite write loop on address range
2214 mtest - simple RAM test
2215 icache - enable or disable instruction cache
2216 dcache - enable or disable data cache
2217 reset - Perform RESET of the CPU
2218 echo - echo args to console
2219 version - print monitor version
2220 help - print online help
2221 ? - alias for 'help'
2224 Monitor Commands - Detailed Description:
2225 ========================================
2229 For now: just type "help <command>".
2232 Note for Redundant Ethernet Interfaces:
2233 =======================================
2235 Some boards come with redundant Ethernet interfaces; U-Boot supports
2236 such configurations and is capable of automatic selection of a
2237 "working" interface when needed. MAC assignment works as follows:
2239 Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
2240 MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
2241 "eth1addr" (=>eth1), "eth2addr", ...
2243 If the network interface stores some valid MAC address (for instance
2244 in SROM), this is used as default address if there is NO correspon-
2245 ding setting in the environment; if the corresponding environment
2246 variable is set, this overrides the settings in the card; that means:
2248 o If the SROM has a valid MAC address, and there is no address in the
2249 environment, the SROM's address is used.
2251 o If there is no valid address in the SROM, and a definition in the
2252 environment exists, then the value from the environment variable is
2255 o If both the SROM and the environment contain a MAC address, and
2256 both addresses are the same, this MAC address is used.
2258 o If both the SROM and the environment contain a MAC address, and the
2259 addresses differ, the value from the environment is used and a
2262 o If neither SROM nor the environment contain a MAC address, an error
2263 is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
2264 a random, locally-assigned MAC is used.
2266 If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
2267 will be programmed into hardware as part of the initialization process. This
2268 may be skipped by setting the appropriate 'ethmacskip' environment variable.
2269 The naming convention is as follows:
2270 "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
2275 U-Boot is capable of booting (and performing other auxiliary operations on)
2276 images in two formats:
2278 New uImage format (FIT)
2279 -----------------------
2281 Flexible and powerful format based on Flattened Image Tree -- FIT (similar
2282 to Flattened Device Tree). It allows the use of images with multiple
2283 components (several kernels, ramdisks, etc.), with contents protected by
2284 SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
2290 Old image format is based on binary files which can be basically anything,
2291 preceded by a special header; see the definitions in include/image.h for
2292 details; basically, the header defines the following image properties:
2294 * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
2295 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
2296 LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
2297 Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
2298 * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
2299 IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
2300 Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
2301 * Compression Type (uncompressed, gzip, bzip2)
2307 The header is marked by a special Magic Number, and both the header
2308 and the data portions of the image are secured against corruption by
2315 Although U-Boot should support any OS or standalone application
2316 easily, the main focus has always been on Linux during the design of
2319 U-Boot includes many features that so far have been part of some
2320 special "boot loader" code within the Linux kernel. Also, any
2321 "initrd" images to be used are no longer part of one big Linux image;
2322 instead, kernel and "initrd" are separate images. This implementation
2323 serves several purposes:
2325 - the same features can be used for other OS or standalone
2326 applications (for instance: using compressed images to reduce the
2327 Flash memory footprint)
2329 - it becomes much easier to port new Linux kernel versions because
2330 lots of low-level, hardware dependent stuff are done by U-Boot
2332 - the same Linux kernel image can now be used with different "initrd"
2333 images; of course this also means that different kernel images can
2334 be run with the same "initrd". This makes testing easier (you don't
2335 have to build a new "zImage.initrd" Linux image when you just
2336 change a file in your "initrd"). Also, a field-upgrade of the
2337 software is easier now.
2343 Porting Linux to U-Boot based systems:
2344 ---------------------------------------
2346 U-Boot cannot save you from doing all the necessary modifications to
2347 configure the Linux device drivers for use with your target hardware
2348 (no, we don't intend to provide a full virtual machine interface to
2351 But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
2353 Just make sure your machine specific header file (for instance
2354 include/asm-ppc/tqm8xx.h) includes the same definition of the Board
2355 Information structure as we define in include/asm-<arch>/u-boot.h,
2356 and make sure that your definition of IMAP_ADDR uses the same value
2357 as your U-Boot configuration in CONFIG_SYS_IMMR.
2359 Note that U-Boot now has a driver model, a unified model for drivers.
2360 If you are adding a new driver, plumb it into driver model. If there
2361 is no uclass available, you are encouraged to create one. See
2365 Configuring the Linux kernel:
2366 -----------------------------
2368 No specific requirements for U-Boot. Make sure you have some root
2369 device (initial ramdisk, NFS) for your target system.
2372 Building a Linux Image:
2373 -----------------------
2375 With U-Boot, "normal" build targets like "zImage" or "bzImage" are
2376 not used. If you use recent kernel source, a new build target
2377 "uImage" will exist which automatically builds an image usable by
2378 U-Boot. Most older kernels also have support for a "pImage" target,
2379 which was introduced for our predecessor project PPCBoot and uses a
2380 100% compatible format.
2384 make TQM850L_defconfig
2389 The "uImage" build target uses a special tool (in 'tools/mkimage') to
2390 encapsulate a compressed Linux kernel image with header information,
2391 CRC32 checksum etc. for use with U-Boot. This is what we are doing:
2393 * build a standard "vmlinux" kernel image (in ELF binary format):
2395 * convert the kernel into a raw binary image:
2397 ${CROSS_COMPILE}-objcopy -O binary \
2398 -R .note -R .comment \
2399 -S vmlinux linux.bin
2401 * compress the binary image:
2405 * package compressed binary image for U-Boot:
2407 mkimage -A ppc -O linux -T kernel -C gzip \
2408 -a 0 -e 0 -n "Linux Kernel Image" \
2409 -d linux.bin.gz uImage
2412 The "mkimage" tool can also be used to create ramdisk images for use
2413 with U-Boot, either separated from the Linux kernel image, or
2414 combined into one file. "mkimage" encapsulates the images with a 64
2415 byte header containing information about target architecture,
2416 operating system, image type, compression method, entry points, time
2417 stamp, CRC32 checksums, etc.
2419 "mkimage" can be called in two ways: to verify existing images and
2420 print the header information, or to build new images.
2422 In the first form (with "-l" option) mkimage lists the information
2423 contained in the header of an existing U-Boot image; this includes
2424 checksum verification:
2426 tools/mkimage -l image
2427 -l ==> list image header information
2429 The second form (with "-d" option) is used to build a U-Boot image
2430 from a "data file" which is used as image payload:
2432 tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
2433 -n name -d data_file image
2434 -A ==> set architecture to 'arch'
2435 -O ==> set operating system to 'os'
2436 -T ==> set image type to 'type'
2437 -C ==> set compression type 'comp'
2438 -a ==> set load address to 'addr' (hex)
2439 -e ==> set entry point to 'ep' (hex)
2440 -n ==> set image name to 'name'
2441 -d ==> use image data from 'datafile'
2443 Right now, all Linux kernels for PowerPC systems use the same load
2444 address (0x00000000), but the entry point address depends on the
2447 - 2.2.x kernels have the entry point at 0x0000000C,
2448 - 2.3.x and later kernels have the entry point at 0x00000000.
2450 So a typical call to build a U-Boot image would read:
2452 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2453 > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
2454 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
2455 > examples/uImage.TQM850L
2456 Image Name: 2.4.4 kernel for TQM850L
2457 Created: Wed Jul 19 02:34:59 2000
2458 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2459 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2460 Load Address: 0x00000000
2461 Entry Point: 0x00000000
2463 To verify the contents of the image (or check for corruption):
2465 -> tools/mkimage -l examples/uImage.TQM850L
2466 Image Name: 2.4.4 kernel for TQM850L
2467 Created: Wed Jul 19 02:34:59 2000
2468 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2469 Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
2470 Load Address: 0x00000000
2471 Entry Point: 0x00000000
2473 NOTE: for embedded systems where boot time is critical you can trade
2474 speed for memory and install an UNCOMPRESSED image instead: this
2475 needs more space in Flash, but boots much faster since it does not
2476 need to be uncompressed:
2478 -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
2479 -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
2480 > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
2481 > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
2482 > examples/uImage.TQM850L-uncompressed
2483 Image Name: 2.4.4 kernel for TQM850L
2484 Created: Wed Jul 19 02:34:59 2000
2485 Image Type: PowerPC Linux Kernel Image (uncompressed)
2486 Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
2487 Load Address: 0x00000000
2488 Entry Point: 0x00000000
2491 Similar you can build U-Boot images from a 'ramdisk.image.gz' file
2492 when your kernel is intended to use an initial ramdisk:
2494 -> tools/mkimage -n 'Simple Ramdisk Image' \
2495 > -A ppc -O linux -T ramdisk -C gzip \
2496 > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
2497 Image Name: Simple Ramdisk Image
2498 Created: Wed Jan 12 14:01:50 2000
2499 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2500 Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
2501 Load Address: 0x00000000
2502 Entry Point: 0x00000000
2504 The "dumpimage" tool can be used to disassemble or list the contents of images
2505 built by mkimage. See dumpimage's help output (-h) for details.
2507 Installing a Linux Image:
2508 -------------------------
2510 To downloading a U-Boot image over the serial (console) interface,
2511 you must convert the image to S-Record format:
2513 objcopy -I binary -O srec examples/image examples/image.srec
2515 The 'objcopy' does not understand the information in the U-Boot
2516 image header, so the resulting S-Record file will be relative to
2517 address 0x00000000. To load it to a given address, you need to
2518 specify the target address as 'offset' parameter with the 'loads'
2521 Example: install the image to address 0x40100000 (which on the
2522 TQM8xxL is in the first Flash bank):
2524 => erase 40100000 401FFFFF
2530 ## Ready for S-Record download ...
2531 ~>examples/image.srec
2532 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
2534 15989 15990 15991 15992
2535 [file transfer complete]
2537 ## Start Addr = 0x00000000
2540 You can check the success of the download using the 'iminfo' command;
2541 this includes a checksum verification so you can be sure no data
2542 corruption happened:
2546 ## Checking Image at 40100000 ...
2547 Image Name: 2.2.13 for initrd on TQM850L
2548 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2549 Data Size: 335725 Bytes = 327 kB = 0 MB
2550 Load Address: 00000000
2551 Entry Point: 0000000c
2552 Verifying Checksum ... OK
2558 The "bootm" command is used to boot an application that is stored in
2559 memory (RAM or Flash). In case of a Linux kernel image, the contents
2560 of the "bootargs" environment variable is passed to the kernel as
2561 parameters. You can check and modify this variable using the
2562 "printenv" and "setenv" commands:
2565 => printenv bootargs
2566 bootargs=root=/dev/ram
2568 => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2570 => printenv bootargs
2571 bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2574 ## Booting Linux kernel at 40020000 ...
2575 Image Name: 2.2.13 for NFS on TQM850L
2576 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2577 Data Size: 381681 Bytes = 372 kB = 0 MB
2578 Load Address: 00000000
2579 Entry Point: 0000000c
2580 Verifying Checksum ... OK
2581 Uncompressing Kernel Image ... OK
2582 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
2583 Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
2584 time_init: decrementer frequency = 187500000/60
2585 Calibrating delay loop... 49.77 BogoMIPS
2586 Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
2589 If you want to boot a Linux kernel with initial RAM disk, you pass
2590 the memory addresses of both the kernel and the initrd image (PPBCOOT
2591 format!) to the "bootm" command:
2593 => imi 40100000 40200000
2595 ## Checking Image at 40100000 ...
2596 Image Name: 2.2.13 for initrd on TQM850L
2597 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2598 Data Size: 335725 Bytes = 327 kB = 0 MB
2599 Load Address: 00000000
2600 Entry Point: 0000000c
2601 Verifying Checksum ... OK
2603 ## Checking Image at 40200000 ...
2604 Image Name: Simple Ramdisk Image
2605 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2606 Data Size: 566530 Bytes = 553 kB = 0 MB
2607 Load Address: 00000000
2608 Entry Point: 00000000
2609 Verifying Checksum ... OK
2611 => bootm 40100000 40200000
2612 ## Booting Linux kernel at 40100000 ...
2613 Image Name: 2.2.13 for initrd on TQM850L
2614 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2615 Data Size: 335725 Bytes = 327 kB = 0 MB
2616 Load Address: 00000000
2617 Entry Point: 0000000c
2618 Verifying Checksum ... OK
2619 Uncompressing Kernel Image ... OK
2620 ## Loading RAMDisk Image at 40200000 ...
2621 Image Name: Simple Ramdisk Image
2622 Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
2623 Data Size: 566530 Bytes = 553 kB = 0 MB
2624 Load Address: 00000000
2625 Entry Point: 00000000
2626 Verifying Checksum ... OK
2627 Loading Ramdisk ... OK
2628 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
2629 Boot arguments: root=/dev/ram
2630 time_init: decrementer frequency = 187500000/60
2631 Calibrating delay loop... 49.77 BogoMIPS
2633 RAMDISK: Compressed image found at block 0
2634 VFS: Mounted root (ext2 filesystem).
2638 Boot Linux and pass a flat device tree:
2641 First, U-Boot must be compiled with the appropriate defines. See the section
2642 titled "Linux Kernel Interface" above for a more in depth explanation. The
2643 following is an example of how to start a kernel and pass an updated
2649 oft=oftrees/mpc8540ads.dtb
2650 => tftp $oftaddr $oft
2651 Speed: 1000, full duplex
2653 TFTP from server 192.168.1.1; our IP address is 192.168.1.101
2654 Filename 'oftrees/mpc8540ads.dtb'.
2655 Load address: 0x300000
2658 Bytes transferred = 4106 (100a hex)
2659 => tftp $loadaddr $bootfile
2660 Speed: 1000, full duplex
2662 TFTP from server 192.168.1.1; our IP address is 192.168.1.2
2664 Load address: 0x200000
2665 Loading:############
2667 Bytes transferred = 1029407 (fb51f hex)
2672 => bootm $loadaddr - $oftaddr
2673 ## Booting image at 00200000 ...
2674 Image Name: Linux-2.6.17-dirty
2675 Image Type: PowerPC Linux Kernel Image (gzip compressed)
2676 Data Size: 1029343 Bytes = 1005.2 kB
2677 Load Address: 00000000
2678 Entry Point: 00000000
2679 Verifying Checksum ... OK
2680 Uncompressing Kernel Image ... OK
2681 Booting using flat device tree at 0x300000
2682 Using MPC85xx ADS machine description
2683 Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
2687 More About U-Boot Image Types:
2688 ------------------------------
2690 U-Boot supports the following image types:
2692 "Standalone Programs" are directly runnable in the environment
2693 provided by U-Boot; it is expected that (if they behave
2694 well) you can continue to work in U-Boot after return from
2695 the Standalone Program.
2696 "OS Kernel Images" are usually images of some Embedded OS which
2697 will take over control completely. Usually these programs
2698 will install their own set of exception handlers, device
2699 drivers, set up the MMU, etc. - this means, that you cannot
2700 expect to re-enter U-Boot except by resetting the CPU.
2701 "RAMDisk Images" are more or less just data blocks, and their
2702 parameters (address, size) are passed to an OS kernel that is
2704 "Multi-File Images" contain several images, typically an OS
2705 (Linux) kernel image and one or more data images like
2706 RAMDisks. This construct is useful for instance when you want
2707 to boot over the network using BOOTP etc., where the boot
2708 server provides just a single image file, but you want to get
2709 for instance an OS kernel and a RAMDisk image.
2711 "Multi-File Images" start with a list of image sizes, each
2712 image size (in bytes) specified by an "uint32_t" in network
2713 byte order. This list is terminated by an "(uint32_t)0".
2714 Immediately after the terminating 0 follow the images, one by
2715 one, all aligned on "uint32_t" boundaries (size rounded up to
2716 a multiple of 4 bytes).
2718 "Firmware Images" are binary images containing firmware (like
2719 U-Boot or FPGA images) which usually will be programmed to
2722 "Script files" are command sequences that will be executed by
2723 U-Boot's command interpreter; this feature is especially
2724 useful when you configure U-Boot to use a real shell (hush)
2725 as command interpreter.
2727 Booting the Linux zImage:
2728 -------------------------
2730 On some platforms, it's possible to boot Linux zImage. This is done
2731 using the "bootz" command. The syntax of "bootz" command is the same
2732 as the syntax of "bootm" command.
2734 Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
2735 kernel with raw initrd images. The syntax is slightly different, the
2736 address of the initrd must be augmented by it's size, in the following
2737 format: "<initrd addres>:<initrd size>".
2743 One of the features of U-Boot is that you can dynamically load and
2744 run "standalone" applications, which can use some resources of
2745 U-Boot like console I/O functions or interrupt services.
2747 Two simple examples are included with the sources:
2752 'examples/hello_world.c' contains a small "Hello World" Demo
2753 application; it is automatically compiled when you build U-Boot.
2754 It's configured to run at address 0x00040004, so you can play with it
2758 ## Ready for S-Record download ...
2759 ~>examples/hello_world.srec
2760 1 2 3 4 5 6 7 8 9 10 11 ...
2761 [file transfer complete]
2763 ## Start Addr = 0x00040004
2765 => go 40004 Hello World! This is a test.
2766 ## Starting application at 0x00040004 ...
2777 Hit any key to exit ...
2779 ## Application terminated, rc = 0x0
2781 Another example, which demonstrates how to register a CPM interrupt
2782 handler with the U-Boot code, can be found in 'examples/timer.c'.
2783 Here, a CPM timer is set up to generate an interrupt every second.
2784 The interrupt service routine is trivial, just printing a '.'
2785 character, but this is just a demo program. The application can be
2786 controlled by the following keys:
2788 ? - print current values og the CPM Timer registers
2789 b - enable interrupts and start timer
2790 e - stop timer and disable interrupts
2791 q - quit application
2794 ## Ready for S-Record download ...
2795 ~>examples/timer.srec
2796 1 2 3 4 5 6 7 8 9 10 11 ...
2797 [file transfer complete]
2799 ## Start Addr = 0x00040004
2802 ## Starting application at 0x00040004 ...
2805 tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
2808 [q, b, e, ?] Set interval 1000000 us
2811 [q, b, e, ?] ........
2812 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
2815 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
2818 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
2821 tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
2823 [q, b, e, ?] ...Stopping timer
2825 [q, b, e, ?] ## Application terminated, rc = 0x0
2831 Over time, many people have reported problems when trying to use the
2832 "minicom" terminal emulation program for serial download. I (wd)
2833 consider minicom to be broken, and recommend not to use it. Under
2834 Unix, I recommend to use C-Kermit for general purpose use (and
2835 especially for kermit binary protocol download ("loadb" command), and
2836 use "cu" for S-Record download ("loads" command). See
2837 https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
2838 for help with kermit.
2841 Nevertheless, if you absolutely want to use it try adding this
2842 configuration to your "File transfer protocols" section:
2844 Name Program Name U/D FullScr IO-Red. Multi
2845 X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
2846 Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
2852 Starting at version 0.9.2, U-Boot supports NetBSD both as host
2853 (build U-Boot) and target system (boots NetBSD/mpc8xx).
2855 Building requires a cross environment; it is known to work on
2856 NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
2857 need gmake since the Makefiles are not compatible with BSD make).
2858 Note that the cross-powerpc package does not install include files;
2859 attempting to build U-Boot will fail because <machine/ansi.h> is
2860 missing. This file has to be installed and patched manually:
2862 # cd /usr/pkg/cross/powerpc-netbsd/include
2864 # ln -s powerpc machine
2865 # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
2866 # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
2868 Native builds *don't* work due to incompatibilities between native
2869 and U-Boot include files.
2871 Booting assumes that (the first part of) the image booted is a
2872 stage-2 loader which in turn loads and then invokes the kernel
2873 proper. Loader sources will eventually appear in the NetBSD source
2874 tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
2875 meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
2878 Implementation Internals:
2879 =========================
2881 The following is not intended to be a complete description of every
2882 implementation detail. However, it should help to understand the
2883 inner workings of U-Boot and make it easier to port it to custom
2887 Initial Stack, Global Data:
2888 ---------------------------
2890 The implementation of U-Boot is complicated by the fact that U-Boot
2891 starts running out of ROM (flash memory), usually without access to
2892 system RAM (because the memory controller is not initialized yet).
2893 This means that we don't have writable Data or BSS segments, and BSS
2894 is not initialized as zero. To be able to get a C environment working
2895 at all, we have to allocate at least a minimal stack. Implementation
2896 options for this are defined and restricted by the CPU used: Some CPU
2897 models provide on-chip memory (like the IMMR area on MPC8xx and
2898 MPC826x processors), on others (parts of) the data cache can be
2899 locked as (mis-) used as memory, etc.
2901 Chris Hallinan posted a good summary of these issues to the
2902 U-Boot mailing list:
2904 Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
2905 From: "Chris Hallinan" <clh@net1plus.com>
2906 Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
2909 Correct me if I'm wrong, folks, but the way I understand it
2910 is this: Using DCACHE as initial RAM for Stack, etc, does not
2911 require any physical RAM backing up the cache. The cleverness
2912 is that the cache is being used as a temporary supply of
2913 necessary storage before the SDRAM controller is setup. It's
2914 beyond the scope of this list to explain the details, but you
2915 can see how this works by studying the cache architecture and
2916 operation in the architecture and processor-specific manuals.
2918 OCM is On Chip Memory, which I believe the 405GP has 4K. It
2919 is another option for the system designer to use as an
2920 initial stack/RAM area prior to SDRAM being available. Either
2921 option should work for you. Using CS 4 should be fine if your
2922 board designers haven't used it for something that would
2923 cause you grief during the initial boot! It is frequently not
2926 CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
2927 with your processor/board/system design. The default value
2928 you will find in any recent u-boot distribution in
2929 walnut.h should work for you. I'd set it to a value larger
2930 than your SDRAM module. If you have a 64MB SDRAM module, set
2931 it above 400_0000. Just make sure your board has no resources
2932 that are supposed to respond to that address! That code in
2933 start.S has been around a while and should work as is when
2934 you get the config right.
2939 It is essential to remember this, since it has some impact on the C
2940 code for the initialization procedures:
2942 * Initialized global data (data segment) is read-only. Do not attempt
2945 * Do not use any uninitialized global data (or implicitly initialized
2946 as zero data - BSS segment) at all - this is undefined, initiali-
2947 zation is performed later (when relocating to RAM).
2949 * Stack space is very limited. Avoid big data buffers or things like
2952 Having only the stack as writable memory limits means we cannot use
2953 normal global data to share information between the code. But it
2954 turned out that the implementation of U-Boot can be greatly
2955 simplified by making a global data structure (gd_t) available to all
2956 functions. We could pass a pointer to this data as argument to _all_
2957 functions, but this would bloat the code. Instead we use a feature of
2958 the GCC compiler (Global Register Variables) to share the data: we
2959 place a pointer (gd) to the global data into a register which we
2960 reserve for this purpose.
2962 When choosing a register for such a purpose we are restricted by the
2963 relevant (E)ABI specifications for the current architecture, and by
2964 GCC's implementation.
2966 For PowerPC, the following registers have specific use:
2968 R2: reserved for system use
2969 R3-R4: parameter passing and return values
2970 R5-R10: parameter passing
2971 R13: small data area pointer
2975 (U-Boot also uses R12 as internal GOT pointer. r12
2976 is a volatile register so r12 needs to be reset when
2977 going back and forth between asm and C)
2979 ==> U-Boot will use R2 to hold a pointer to the global data
2981 Note: on PPC, we could use a static initializer (since the
2982 address of the global data structure is known at compile time),
2983 but it turned out that reserving a register results in somewhat
2984 smaller code - although the code savings are not that big (on
2985 average for all boards 752 bytes for the whole U-Boot image,
2986 624 text + 127 data).
2988 On ARM, the following registers are used:
2990 R0: function argument word/integer result
2991 R1-R3: function argument word
2992 R9: platform specific
2993 R10: stack limit (used only if stack checking is enabled)
2994 R11: argument (frame) pointer
2995 R12: temporary workspace
2998 R15: program counter
3000 ==> U-Boot will use R9 to hold a pointer to the global data
3002 Note: on ARM, only R_ARM_RELATIVE relocations are supported.
3004 On Nios II, the ABI is documented here:
3005 https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
3007 ==> U-Boot will use gp to hold a pointer to the global data
3009 Note: on Nios II, we give "-G0" option to gcc and don't use gp
3010 to access small data sections, so gp is free.
3012 On RISC-V, the following registers are used:
3014 x0: hard-wired zero (zero)
3015 x1: return address (ra)
3016 x2: stack pointer (sp)
3017 x3: global pointer (gp)
3018 x4: thread pointer (tp)
3019 x5: link register (t0)
3020 x8: frame pointer (fp)
3021 x10-x11: arguments/return values (a0-1)
3022 x12-x17: arguments (a2-7)
3023 x28-31: temporaries (t3-6)
3024 pc: program counter (pc)
3026 ==> U-Boot will use gp to hold a pointer to the global data
3031 U-Boot runs in system state and uses physical addresses, i.e. the
3032 MMU is not used either for address mapping nor for memory protection.
3034 The available memory is mapped to fixed addresses using the memory
3035 controller. In this process, a contiguous block is formed for each
3036 memory type (Flash, SDRAM, SRAM), even when it consists of several
3037 physical memory banks.
3039 U-Boot is installed in the first 128 kB of the first Flash bank (on
3040 TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
3041 booting and sizing and initializing DRAM, the code relocates itself
3042 to the upper end of DRAM. Immediately below the U-Boot code some
3043 memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
3044 configuration setting]. Below that, a structure with global Board
3045 Info data is placed, followed by the stack (growing downward).
3047 Additionally, some exception handler code is copied to the low 8 kB
3048 of DRAM (0x00000000 ... 0x00001FFF).
3050 So a typical memory configuration with 16 MB of DRAM could look like
3053 0x0000 0000 Exception Vector code
3056 0x0000 2000 Free for Application Use
3062 0x00FB FF20 Monitor Stack (Growing downward)
3063 0x00FB FFAC Board Info Data and permanent copy of global data
3064 0x00FC 0000 Malloc Arena
3067 0x00FE 0000 RAM Copy of Monitor Code
3068 ... eventually: LCD or video framebuffer
3069 ... eventually: pRAM (Protected RAM - unchanged by reset)
3070 0x00FF FFFF [End of RAM]
3073 System Initialization:
3074 ----------------------
3076 In the reset configuration, U-Boot starts at the reset entry point
3077 (on most PowerPC systems at address 0x00000100). Because of the reset
3078 configuration for CS0# this is a mirror of the on board Flash memory.
3079 To be able to re-map memory U-Boot then jumps to its link address.
3080 To be able to implement the initialization code in C, a (small!)
3081 initial stack is set up in the internal Dual Ported RAM (in case CPUs
3082 which provide such a feature like), or in a locked part of the data
3083 cache. After that, U-Boot initializes the CPU core, the caches and
3086 Next, all (potentially) available memory banks are mapped using a
3087 preliminary mapping. For example, we put them on 512 MB boundaries
3088 (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
3089 on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
3090 programmed for SDRAM access. Using the temporary configuration, a
3091 simple memory test is run that determines the size of the SDRAM
3094 When there is more than one SDRAM bank, and the banks are of
3095 different size, the largest is mapped first. For equal size, the first
3096 bank (CS2#) is mapped first. The first mapping is always for address
3097 0x00000000, with any additional banks following immediately to create
3098 contiguous memory starting from 0.
3100 Then, the monitor installs itself at the upper end of the SDRAM area
3101 and allocates memory for use by malloc() and for the global Board
3102 Info data; also, the exception vector code is copied to the low RAM
3103 pages, and the final stack is set up.
3105 Only after this relocation will you have a "normal" C environment;
3106 until that you are restricted in several ways, mostly because you are
3107 running from ROM, and because the code will have to be relocated to a
3111 U-Boot Porting Guide:
3112 ----------------------
3114 [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
3118 int main(int argc, char *argv[])
3120 sighandler_t no_more_time;
3122 signal(SIGALRM, no_more_time);
3123 alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
3125 if (available_money > available_manpower) {
3126 Pay consultant to port U-Boot;
3130 Download latest U-Boot source;
3132 Subscribe to u-boot mailing list;
3135 email("Hi, I am new to U-Boot, how do I get started?");
3138 Read the README file in the top level directory;
3139 Read https://www.denx.de/wiki/bin/view/DULG/Manual;
3140 Read applicable doc/README.*;
3141 Read the source, Luke;
3142 /* find . -name "*.[chS]" | xargs grep -i <keyword> */
3145 if (available_money > toLocalCurrency ($2500))
3148 Add a lot of aggravation and time;
3150 if (a similar board exists) { /* hopefully... */
3151 cp -a board/<similar> board/<myboard>
3152 cp include/configs/<similar>.h include/configs/<myboard>.h
3154 Create your own board support subdirectory;
3155 Create your own board include/configs/<myboard>.h file;
3157 Edit new board/<myboard> files
3158 Edit new include/configs/<myboard>.h
3163 Add / modify source code;
3167 email("Hi, I am having problems...");
3169 Send patch file to the U-Boot email list;
3170 if (reasonable critiques)
3171 Incorporate improvements from email list code review;
3173 Defend code as written;
3179 void no_more_time (int sig)
3188 All contributions to U-Boot should conform to the Linux kernel
3189 coding style; see the kernel coding style guide at
3190 https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
3191 script "scripts/Lindent" in your Linux kernel source directory.
3193 Source files originating from a different project (for example the
3194 MTD subsystem) are generally exempt from these guidelines and are not
3195 reformatted to ease subsequent migration to newer versions of those
3198 Please note that U-Boot is implemented in C (and to some small parts in
3199 Assembler); no C++ is used, so please do not use C++ style comments (//)
3202 Please also stick to the following formatting rules:
3203 - remove any trailing white space
3204 - use TAB characters for indentation and vertical alignment, not spaces
3205 - make sure NOT to use DOS '\r\n' line feeds
3206 - do not add more than 2 consecutive empty lines to source files
3207 - do not add trailing empty lines to source files
3209 Submissions which do not conform to the standards may be returned
3210 with a request to reformat the changes.
3216 Since the number of patches for U-Boot is growing, we need to
3217 establish some rules. Submissions which do not conform to these rules
3218 may be rejected, even when they contain important and valuable stuff.
3220 Please see https://www.denx.de/wiki/U-Boot/Patches for details.
3222 Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
3223 see https://lists.denx.de/listinfo/u-boot
3225 When you send a patch, please include the following information with
3228 * For bug fixes: a description of the bug and how your patch fixes
3229 this bug. Please try to include a way of demonstrating that the
3230 patch actually fixes something.
3232 * For new features: a description of the feature and your
3235 * For major contributions, add a MAINTAINERS file with your
3236 information and associated file and directory references.
3238 * When you add support for a new board, don't forget to add a
3239 maintainer e-mail address to the boards.cfg file, too.
3241 * If your patch adds new configuration options, don't forget to
3242 document these in the README file.
3244 * The patch itself. If you are using git (which is *strongly*
3245 recommended) you can easily generate the patch using the
3246 "git format-patch". If you then use "git send-email" to send it to
3247 the U-Boot mailing list, you will avoid most of the common problems
3248 with some other mail clients.
3250 If you cannot use git, use "diff -purN OLD NEW". If your version of
3251 diff does not support these options, then get the latest version of
3254 The current directory when running this command shall be the parent
3255 directory of the U-Boot source tree (i. e. please make sure that
3256 your patch includes sufficient directory information for the
3259 We prefer patches as plain text. MIME attachments are discouraged,
3260 and compressed attachments must not be used.
3262 * If one logical set of modifications affects or creates several
3263 files, all these changes shall be submitted in a SINGLE patch file.
3265 * Changesets that contain different, unrelated modifications shall be
3266 submitted as SEPARATE patches, one patch per changeset.
3271 * Before sending the patch, run the buildman script on your patched
3272 source tree and make sure that no errors or warnings are reported
3273 for any of the boards.
3275 * Keep your modifications to the necessary minimum: A patch
3276 containing several unrelated changes or arbitrary reformats will be
3277 returned with a request to re-formatting / split it.
3279 * If you modify existing code, make sure that your new code does not
3280 add to the memory footprint of the code ;-) Small is beautiful!
3281 When adding new features, these should compile conditionally only
3282 (using #ifdef), and the resulting code with the new feature
3283 disabled must not need more memory than the old code without your
3286 * Remember that there is a size limit of 100 kB per message on the
3287 u-boot mailing list. Bigger patches will be moderated. If they are
3288 reasonable and not too big, they will be acknowledged. But patches
3289 bigger than the size limit should be avoided.