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Simon Glass <sjg@chromium.org> says: When the SPL build-phase was first created it was designed to solve a particular problem (the need to init SDRAM so that U-Boot proper could be loaded). It has since expanded to become an important part of U-Boot, with three phases now present: TPL, VPL and SPL Due to this history, the term 'SPL' is used to mean both a particular phase (the one before U-Boot proper) and all the non-proper phases. This has become confusing. For a similar reason CONFIG_SPL_BUILD is set to 'y' for all 'SPL' phases, not just SPL. So code which can only be compiled for actual SPL, for example, must use something like this: #if defined(CONFIG_SPL_BUILD) && !defined(CONFIG_TPL_BUILD) In Makefiles we have similar issues. SPL_ has been used as a variable which expands to either SPL_ or nothing, to chose between options like CONFIG_BLK and CONFIG_SPL_BLK. When TPL appeared, a new SPL_TPL variable was created which expanded to 'SPL_', 'TPL_' or nothing. Later it was updated to support 'VPL_' as well. This series starts a change in terminology and usage to resolve the above issues: - The word 'xPL' is used instead of 'SPL' to mean a non-proper build - A new CONFIG_XPL_BUILD define indicates that the current build is an 'xPL' build - The existing CONFIG_SPL_BUILD is changed to mean SPL; it is not now defined for TPL and VPL phases - The existing SPL_ Makefile variable is renamed to SPL_ - The existing SPL_TPL Makefile variable is renamed to PHASE_ It should be noted that xpl_phase() can generally be used instead of the above CONFIGs without a code-space or run-time penalty. This series does not attempt to convert all of U-Boot to use this new terminology but it makes a start. In particular, renaming spl.h and common/spl seems like a bridge too far at this point. The series is fully bisectable. It has also been checked to ensure there are no code-size changes on any commit.
2474 lines
85 KiB
Plaintext
2474 lines
85 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0+
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#
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# (C) Copyright 2000 - 2013
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# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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Summary:
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========
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This directory contains the source code for U-Boot, a boot loader for
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Embedded boards based on PowerPC, ARM, MIPS and several other
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processors, which can be installed in a boot ROM and used to
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initialize and test the hardware or to download and run application
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code.
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The development of U-Boot is closely related to Linux: some parts of
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the source code originate in the Linux source tree, we have some
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header files in common, and special provision has been made to
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support booting of Linux images.
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Some attention has been paid to make this software easily
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configurable and extendable. For instance, all monitor commands are
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implemented with the same call interface, so that it's very easy to
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add new commands. Also, instead of permanently adding rarely used
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code (for instance hardware test utilities) to the monitor, you can
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load and run it dynamically.
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Status:
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=======
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In general, all boards for which a default configuration file exists in the
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configs/ directory have been tested to some extent and can be considered
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"working". In fact, many of them are used in production systems.
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In case of problems you can use
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scripts/get_maintainer.pl <path>
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to identify the people or companies responsible for various boards and
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subsystems. Or have a look at the git log.
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Where to get help:
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==================
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In case you have questions about, problems with or contributions for
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U-Boot, you should send a message to the U-Boot mailing list at
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<u-boot@lists.denx.de>. There is also an archive of previous traffic
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on the mailing list - please search the archive before asking FAQ's.
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Please see https://lists.denx.de/pipermail/u-boot and
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https://marc.info/?l=u-boot
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Where to get source code:
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=========================
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The U-Boot source code is maintained in the Git repository at
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https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
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https://source.denx.de/u-boot/u-boot
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The "Tags" links on this page allow you to download tarballs of
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any version you might be interested in. Official releases are also
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available from the DENX file server through HTTPS or FTP.
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https://ftp.denx.de/pub/u-boot/
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ftp://ftp.denx.de/pub/u-boot/
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Where we come from:
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===================
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- start from 8xxrom sources
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- create PPCBoot project (https://sourceforge.net/projects/ppcboot)
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- clean up code
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- make it easier to add custom boards
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- make it possible to add other [PowerPC] CPUs
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- extend functions, especially:
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* Provide extended interface to Linux boot loader
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* S-Record download
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* network boot
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* ATA disk / SCSI ... boot
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- create ARMBoot project (https://sourceforge.net/projects/armboot)
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- add other CPU families (starting with ARM)
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- create U-Boot project (https://sourceforge.net/projects/u-boot)
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- current project page: see https://www.denx.de/wiki/U-Boot
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Names and Spelling:
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===================
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The "official" name of this project is "Das U-Boot". The spelling
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"U-Boot" shall be used in all written text (documentation, comments
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in source files etc.). Example:
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This is the README file for the U-Boot project.
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File names etc. shall be based on the string "u-boot". Examples:
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include/asm-ppc/u-boot.h
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#include <asm/u-boot.h>
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Variable names, preprocessor constants etc. shall be either based on
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the string "u_boot" or on "U_BOOT". Example:
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U_BOOT_VERSION u_boot_logo
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IH_OS_U_BOOT u_boot_hush_start
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Software Configuration:
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=======================
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Selection of Processor Architecture and Board Type:
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---------------------------------------------------
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For all supported boards there are ready-to-use default
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configurations available; just type "make <board_name>_defconfig".
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Example: For a TQM823L module type:
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cd u-boot
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make TQM823L_defconfig
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Note: If you're looking for the default configuration file for a board
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you're sure used to be there but is now missing, check the file
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doc/README.scrapyard for a list of no longer supported boards.
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Sandbox Environment:
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--------------------
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U-Boot can be built natively to run on a Linux host using the 'sandbox'
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board. This allows feature development which is not board- or architecture-
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specific to be undertaken on a native platform. The sandbox is also used to
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run some of U-Boot's tests.
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See doc/arch/sandbox/sandbox.rst for more details.
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The following options need to be configured:
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- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
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- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
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- 85xx CPU Options:
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CONFIG_SYS_PPC64
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Specifies that the core is a 64-bit PowerPC implementation (implements
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the "64" category of the Power ISA). This is necessary for ePAPR
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compliance, among other possible reasons.
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CONFIG_SYS_FSL_ERRATUM_A004510
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Enables a workaround for erratum A004510. If set,
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then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
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CFG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
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CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
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CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
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Defines one or two SoC revisions (low 8 bits of SVR)
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for which the A004510 workaround should be applied.
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The rest of SVR is either not relevant to the decision
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of whether the erratum is present (e.g. p2040 versus
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p2041) or is implied by the build target, which controls
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whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
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See Freescale App Note 4493 for more information about
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this erratum.
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CFG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
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This is the value to write into CCSR offset 0x18600
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according to the A004510 workaround.
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CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
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Single Source Clock is clocking mode present in some of FSL SoC's.
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In this mode, a single differential clock is used to supply
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clocks to the sysclock, ddrclock and usbclock.
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- Generic CPU options:
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CONFIG_SYS_FSL_DDR
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Freescale DDR driver in use. This type of DDR controller is
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found in mpc83xx, mpc85xx as well as some ARM core SoCs.
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CFG_SYS_FSL_DDR_ADDR
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Freescale DDR memory-mapped register base.
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CONFIG_SYS_FSL_IFC_CLK_DIV
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Defines divider of platform clock(clock input to IFC controller).
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CONFIG_SYS_FSL_LBC_CLK_DIV
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Defines divider of platform clock(clock input to eLBC controller).
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CFG_SYS_FSL_DDR_SDRAM_BASE_PHY
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Physical address from the view of DDR controllers. It is the
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same as CFG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
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it could be different for ARM SoCs.
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- ARM options:
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CFG_SYS_EXCEPTION_VECTORS_HIGH
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Select high exception vectors of the ARM core, e.g., do not
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clear the V bit of the c1 register of CP15.
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COUNTER_FREQUENCY
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Generic timer clock source frequency.
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COUNTER_FREQUENCY_REAL
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Generic timer clock source frequency if the real clock is
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different from COUNTER_FREQUENCY, and can only be determined
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at run time.
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- Linux Kernel Interface:
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CONFIG_OF_LIBFDT
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New kernel versions are expecting firmware settings to be
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passed using flattened device trees (based on open firmware
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concepts).
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CONFIG_OF_LIBFDT
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* New libfdt-based support
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* Adds the "fdt" command
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* The bootm command automatically updates the fdt
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OF_TBCLK - The timebase frequency.
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boards with QUICC Engines require OF_QE to set UCC MAC
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addresses
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CONFIG_OF_IDE_FIXUP
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U-Boot can detect if an IDE device is present or not.
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If not, and this new config option is activated, U-Boot
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removes the ATA node from the DTS before booting Linux,
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so the Linux IDE driver does not probe the device and
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crash. This is needed for buggy hardware (uc101) where
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no pull down resistor is connected to the signal IDE5V_DD7.
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- vxWorks boot parameters:
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bootvx constructs a valid bootline using the following
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environments variables: bootdev, bootfile, ipaddr, netmask,
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serverip, gatewayip, hostname, othbootargs.
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It loads the vxWorks image pointed bootfile.
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Note: If a "bootargs" environment is defined, it will override
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the defaults discussed just above.
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- Cache Configuration for ARM:
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CFG_SYS_PL310_BASE - Physical base address of PL310
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controller register space
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- Serial Ports:
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CFG_PL011_CLOCK
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If you have Amba PrimeCell PL011 UARTs, set this variable to
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the clock speed of the UARTs.
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CFG_PL01x_PORTS
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If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
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define this to a list of base addresses for each (supported)
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port. See e.g. include/configs/versatile.h
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CONFIG_SERIAL_HW_FLOW_CONTROL
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Define this variable to enable hw flow control in serial driver.
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Current user of this option is drivers/serial/nsl16550.c driver
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- Removal of commands
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If no commands are needed to boot, you can disable
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CONFIG_CMDLINE to remove them. In this case, the command line
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will not be available, and when U-Boot wants to execute the
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boot command (on start-up) it will call board_run_command()
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instead. This can reduce image size significantly for very
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simple boot procedures.
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- Regular expression support:
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CONFIG_REGEX
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If this variable is defined, U-Boot is linked against
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the SLRE (Super Light Regular Expression) library,
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which adds regex support to some commands, as for
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example "env grep" and "setexpr".
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- Watchdog:
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CFG_SYS_WATCHDOG_FREQ
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Some platforms automatically call WATCHDOG_RESET()
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from the timer interrupt handler every
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CFG_SYS_WATCHDOG_FREQ interrupts. If not set by the
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board configuration file, a default of CONFIG_SYS_HZ/2
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(i.e. 500) is used. Setting CFG_SYS_WATCHDOG_FREQ
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to 0 disables calling WATCHDOG_RESET() from the timer
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interrupt.
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- GPIO Support:
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The CFG_SYS_I2C_PCA953X_WIDTH option specifies a list of
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chip-ngpio pairs that tell the PCA953X driver the number of
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pins supported by a particular chip.
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Note that if the GPIO device uses I2C, then the I2C interface
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must also be configured. See I2C Support, below.
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- I/O tracing:
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When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
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accesses and can checksum them or write a list of them out
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to memory. See the 'iotrace' command for details. This is
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useful for testing device drivers since it can confirm that
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the driver behaves the same way before and after a code
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change. Currently this is supported on sandbox and arm. To
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add support for your architecture, add '#include <iotrace.h>'
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to the bottom of arch/<arch>/include/asm/io.h and test.
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Example output from the 'iotrace stats' command is below.
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Note that if the trace buffer is exhausted, the checksum will
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still continue to operate.
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iotrace is enabled
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Start: 10000000 (buffer start address)
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Size: 00010000 (buffer size)
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Offset: 00000120 (current buffer offset)
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Output: 10000120 (start + offset)
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Count: 00000018 (number of trace records)
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CRC32: 9526fb66 (CRC32 of all trace records)
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- Timestamp Support:
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When CONFIG_TIMESTAMP is selected, the timestamp
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(date and time) of an image is printed by image
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commands like bootm or iminfo. This option is
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automatically enabled when you select CONFIG_CMD_DATE .
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- Partition Labels (disklabels) Supported:
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Zero or more of the following:
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CONFIG_MAC_PARTITION Apple's MacOS partition table.
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CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
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CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
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bootloader. Note 2TB partition limit; see
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disk/part_efi.c
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CONFIG_SCSI) you must configure support for at
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least one non-MTD partition type as well.
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- NETWORK Support (PCI):
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CONFIG_E1000_SPI
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Utility code for direct access to the SPI bus on Intel 8257x.
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This does not do anything useful unless you set at least one
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of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
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CONFIG_NATSEMI
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Support for National dp83815 chips.
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CONFIG_NS8382X
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Support for National dp8382[01] gigabit chips.
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- NETWORK Support (other):
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CONFIG_CALXEDA_XGMAC
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Support for the Calxeda XGMAC device
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CONFIG_LAN91C96
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Support for SMSC's LAN91C96 chips.
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CONFIG_LAN91C96_USE_32_BIT
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Define this to enable 32 bit addressing
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CFG_SYS_DAVINCI_EMAC_PHY_COUNT
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Define this if you have more then 3 PHYs.
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CONFIG_FTGMAC100
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Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
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CONFIG_FTGMAC100_EGIGA
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Define this to use GE link update with gigabit PHY.
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Define this if FTGMAC100 is connected to gigabit PHY.
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If your system has 10/100 PHY only, it might not occur
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wrong behavior. Because PHY usually return timeout or
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useless data when polling gigabit status and gigabit
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control registers. This behavior won't affect the
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correctnessof 10/100 link speed update.
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CONFIG_SH_ETHER
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Support for Renesas on-chip Ethernet controller
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CFG_SH_ETHER_USE_PORT
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Define the number of ports to be used
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CFG_SH_ETHER_PHY_ADDR
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Define the ETH PHY's address
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CFG_SH_ETHER_CACHE_WRITEBACK
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If this option is set, the driver enables cache flush.
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- TPM Support:
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CONFIG_TPM
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Support TPM devices.
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CONFIG_TPM_TIS_INFINEON
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Support for Infineon i2c bus TPM devices. Only one device
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per system is supported at this time.
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CONFIG_TPM_TIS_I2C_BURST_LIMITATION
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Define the burst count bytes upper limit
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CONFIG_TPM_ST33ZP24
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Support for STMicroelectronics TPM devices. Requires DM_TPM support.
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CONFIG_TPM_ST33ZP24_I2C
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Support for STMicroelectronics ST33ZP24 I2C devices.
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Requires TPM_ST33ZP24 and I2C.
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CONFIG_TPM_ST33ZP24_SPI
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Support for STMicroelectronics ST33ZP24 SPI devices.
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Requires TPM_ST33ZP24 and SPI.
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CONFIG_TPM_ATMEL_TWI
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Support for Atmel TWI TPM device. Requires I2C support.
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CONFIG_TPM_TIS_LPC
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Support for generic parallel port TPM devices. Only one device
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per system is supported at this time.
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CONFIG_TPM
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Define this to enable the TPM support library which provides
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functional interfaces to some TPM commands.
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Requires support for a TPM device.
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CONFIG_TPM_AUTH_SESSIONS
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Define this to enable authorized functions in the TPM library.
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Requires CONFIG_TPM and CONFIG_SHA1.
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- USB Support:
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At the moment only the UHCI host controller is
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supported (PIP405, MIP405); define
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CONFIG_USB_UHCI to enable it.
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define CONFIG_USB_KEYBOARD to enable the USB Keyboard
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and define CONFIG_USB_STORAGE to enable the USB
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storage devices.
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Note:
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Supported are USB Keyboards and USB Floppy drives
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(TEAC FD-05PUB).
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CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
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HW module registers.
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- USB Device:
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Define the below if you wish to use the USB console.
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Once firmware is rebuilt from a serial console issue the
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command "setenv stdin usbtty; setenv stdout usbtty" and
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attach your USB cable. The Unix command "dmesg" should print
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it has found a new device. The environment variable usbtty
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can be set to gserial or cdc_acm to enable your device to
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appear to a USB host as a Linux gserial device or a
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Common Device Class Abstract Control Model serial device.
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If you select usbtty = gserial you should be able to enumerate
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a Linux host by
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# modprobe usbserial vendor=0xVendorID product=0xProductID
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else if using cdc_acm, simply setting the environment
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variable usbtty to be cdc_acm should suffice. The following
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might be defined in YourBoardName.h
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If you have a USB-IF assigned VendorID then you may wish to
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define your own vendor specific values either in BoardName.h
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or directly in usbd_vendor_info.h. If you don't define
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CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
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CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
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should pretend to be a Linux device to it's target host.
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CONFIG_USBD_MANUFACTURER
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Define this string as the name of your company for
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- CONFIG_USBD_MANUFACTURER "my company"
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CONFIG_USBD_PRODUCT_NAME
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Define this string as the name of your product
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- CONFIG_USBD_PRODUCT_NAME "acme usb device"
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CONFIG_USBD_VENDORID
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Define this as your assigned Vendor ID from the USB
|
|
Implementors Forum. This *must* be a genuine Vendor ID
|
|
to avoid polluting the USB namespace.
|
|
- CONFIG_USBD_VENDORID 0xFFFF
|
|
|
|
CONFIG_USBD_PRODUCTID
|
|
Define this as the unique Product ID
|
|
for your device
|
|
- CONFIG_USBD_PRODUCTID 0xFFFF
|
|
|
|
- ULPI Layer Support:
|
|
The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
|
|
the generic ULPI layer. The generic layer accesses the ULPI PHY
|
|
via the platform viewport, so you need both the genric layer and
|
|
the viewport enabled. Currently only Chipidea/ARC based
|
|
viewport is supported.
|
|
To enable the ULPI layer support, define CONFIG_USB_ULPI and
|
|
CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
|
|
If your ULPI phy needs a different reference clock than the
|
|
standard 24 MHz then you have to define CFG_ULPI_REF_CLK to
|
|
the appropriate value in Hz.
|
|
|
|
- MMC Support:
|
|
CONFIG_SH_MMCIF
|
|
Support for Renesas on-chip MMCIF controller
|
|
|
|
CONFIG_SH_MMCIF_ADDR
|
|
Define the base address of MMCIF registers
|
|
|
|
CONFIG_SH_MMCIF_CLK
|
|
Define the clock frequency for MMCIF
|
|
|
|
- USB Device Firmware Update (DFU) class support:
|
|
CONFIG_DFU_OVER_USB
|
|
This enables the USB portion of the DFU USB class
|
|
|
|
CONFIG_DFU_NAND
|
|
This enables support for exposing NAND devices via DFU.
|
|
|
|
CONFIG_DFU_RAM
|
|
This enables support for exposing RAM via DFU.
|
|
Note: DFU spec refer to non-volatile memory usage, but
|
|
allow usages beyond the scope of spec - here RAM usage,
|
|
one that would help mostly the developer.
|
|
|
|
CONFIG_SYS_DFU_DATA_BUF_SIZE
|
|
Dfu transfer uses a buffer before writing data to the
|
|
raw storage device. Make the size (in bytes) of this buffer
|
|
configurable. The size of this buffer is also configurable
|
|
through the "dfu_bufsiz" environment variable.
|
|
|
|
CONFIG_SYS_DFU_MAX_FILE_SIZE
|
|
When updating files rather than the raw storage device,
|
|
we use a static buffer to copy the file into and then write
|
|
the buffer once we've been given the whole file. Define
|
|
this to the maximum filesize (in bytes) for the buffer.
|
|
Default is 4 MiB if undefined.
|
|
|
|
DFU_DEFAULT_POLL_TIMEOUT
|
|
Poll timeout [ms], is the timeout a device can send to the
|
|
host. The host must wait for this timeout before sending
|
|
a subsequent DFU_GET_STATUS request to the device.
|
|
|
|
DFU_MANIFEST_POLL_TIMEOUT
|
|
Poll timeout [ms], which the device sends to the host when
|
|
entering dfuMANIFEST state. Host waits this timeout, before
|
|
sending again an USB request to the device.
|
|
|
|
- Keyboard Support:
|
|
See Kconfig help for available keyboard drivers.
|
|
|
|
- MII/PHY support:
|
|
CONFIG_PHY_CLOCK_FREQ (ppc4xx)
|
|
|
|
The clock frequency of the MII bus
|
|
|
|
CONFIG_PHY_CMD_DELAY (ppc4xx)
|
|
|
|
Some PHY like Intel LXT971A need extra delay after
|
|
command issued before MII status register can be read
|
|
|
|
- BOOTP Recovery Mode:
|
|
CONFIG_BOOTP_RANDOM_DELAY
|
|
|
|
If you have many targets in a network that try to
|
|
boot using BOOTP, you may want to avoid that all
|
|
systems send out BOOTP requests at precisely the same
|
|
moment (which would happen for instance at recovery
|
|
from a power failure, when all systems will try to
|
|
boot, thus flooding the BOOTP server. Defining
|
|
CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
|
|
inserted before sending out BOOTP requests. The
|
|
following delays are inserted then:
|
|
|
|
1st BOOTP request: delay 0 ... 1 sec
|
|
2nd BOOTP request: delay 0 ... 2 sec
|
|
3rd BOOTP request: delay 0 ... 4 sec
|
|
4th and following
|
|
BOOTP requests: delay 0 ... 8 sec
|
|
|
|
CFG_BOOTP_ID_CACHE_SIZE
|
|
|
|
BOOTP packets are uniquely identified using a 32-bit ID. The
|
|
server will copy the ID from client requests to responses and
|
|
U-Boot will use this to determine if it is the destination of
|
|
an incoming response. Some servers will check that addresses
|
|
aren't in use before handing them out (usually using an ARP
|
|
ping) and therefore take up to a few hundred milliseconds to
|
|
respond. Network congestion may also influence the time it
|
|
takes for a response to make it back to the client. If that
|
|
time is too long, U-Boot will retransmit requests. In order
|
|
to allow earlier responses to still be accepted after these
|
|
retransmissions, U-Boot's BOOTP client keeps a small cache of
|
|
IDs. The CFG_BOOTP_ID_CACHE_SIZE controls the size of this
|
|
cache. The default is to keep IDs for up to four outstanding
|
|
requests. Increasing this will allow U-Boot to accept offers
|
|
from a BOOTP client in networks with unusually high latency.
|
|
|
|
- DHCP Advanced Options:
|
|
|
|
- Link-local IP address negotiation:
|
|
Negotiate with other link-local clients on the local network
|
|
for an address that doesn't require explicit configuration.
|
|
This is especially useful if a DHCP server cannot be guaranteed
|
|
to exist in all environments that the device must operate.
|
|
|
|
See doc/README.link-local for more information.
|
|
|
|
- MAC address from environment variables
|
|
|
|
FDT_SEQ_MACADDR_FROM_ENV
|
|
|
|
Fix-up device tree with MAC addresses fetched sequentially from
|
|
environment variables. This config work on assumption that
|
|
non-usable ethernet node of device-tree are either not present
|
|
or their status has been marked as "disabled".
|
|
|
|
- CDP Options:
|
|
CONFIG_CDP_DEVICE_ID
|
|
|
|
The device id used in CDP trigger frames.
|
|
|
|
CONFIG_CDP_DEVICE_ID_PREFIX
|
|
|
|
A two character string which is prefixed to the MAC address
|
|
of the device.
|
|
|
|
CONFIG_CDP_PORT_ID
|
|
|
|
A printf format string which contains the ascii name of
|
|
the port. Normally is set to "eth%d" which sets
|
|
eth0 for the first Ethernet, eth1 for the second etc.
|
|
|
|
CONFIG_CDP_CAPABILITIES
|
|
|
|
A 32bit integer which indicates the device capabilities;
|
|
0x00000010 for a normal host which does not forwards.
|
|
|
|
CONFIG_CDP_VERSION
|
|
|
|
An ascii string containing the version of the software.
|
|
|
|
CONFIG_CDP_PLATFORM
|
|
|
|
An ascii string containing the name of the platform.
|
|
|
|
CONFIG_CDP_TRIGGER
|
|
|
|
A 32bit integer sent on the trigger.
|
|
|
|
CONFIG_CDP_POWER_CONSUMPTION
|
|
|
|
A 16bit integer containing the power consumption of the
|
|
device in .1 of milliwatts.
|
|
|
|
CONFIG_CDP_APPLIANCE_VLAN_TYPE
|
|
|
|
A byte containing the id of the VLAN.
|
|
|
|
- Status LED: CONFIG_LED_STATUS
|
|
|
|
Several configurations allow to display the current
|
|
status using a LED. For instance, the LED will blink
|
|
fast while running U-Boot code, stop blinking as
|
|
soon as a reply to a BOOTP request was received, and
|
|
start blinking slow once the Linux kernel is running
|
|
(supported by a status LED driver in the Linux
|
|
kernel). Defining CONFIG_LED_STATUS enables this
|
|
feature in U-Boot.
|
|
|
|
Additional options:
|
|
|
|
CONFIG_LED_STATUS_GPIO
|
|
The status LED can be connected to a GPIO pin.
|
|
In such cases, the gpio_led driver can be used as a
|
|
status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
|
|
to include the gpio_led driver in the U-Boot binary.
|
|
|
|
CFG_GPIO_LED_INVERTED_TABLE
|
|
Some GPIO connected LEDs may have inverted polarity in which
|
|
case the GPIO high value corresponds to LED off state and
|
|
GPIO low value corresponds to LED on state.
|
|
In such cases CFG_GPIO_LED_INVERTED_TABLE may be defined
|
|
with a list of GPIO LEDs that have inverted polarity.
|
|
|
|
- I2C Support:
|
|
CFG_SYS_NUM_I2C_BUSES
|
|
Hold the number of i2c buses you want to use.
|
|
|
|
CFG_SYS_I2C_BUSES
|
|
hold a list of buses you want to use
|
|
|
|
CFG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
|
|
{0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
|
|
{0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
|
|
{0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
|
|
{0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
|
|
{0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
|
|
{1, {I2C_NULL_HOP}}, \
|
|
{1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
|
|
{1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
|
|
}
|
|
|
|
which defines
|
|
bus 0 on adapter 0 without a mux
|
|
bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
|
|
bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
|
|
bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
|
|
bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
|
|
bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
|
|
bus 6 on adapter 1 without a mux
|
|
bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
|
|
bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
|
|
|
|
If you do not have i2c muxes on your board, omit this define.
|
|
|
|
- Legacy I2C Support:
|
|
If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
|
|
then the following macros need to be defined (examples are
|
|
from include/configs/lwmon.h):
|
|
|
|
I2C_INIT
|
|
|
|
(Optional). Any commands necessary to enable the I2C
|
|
controller or configure ports.
|
|
|
|
eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
|
|
|
|
I2C_ACTIVE
|
|
|
|
The code necessary to make the I2C data line active
|
|
(driven). If the data line is open collector, this
|
|
define can be null.
|
|
|
|
eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
|
|
|
|
I2C_TRISTATE
|
|
|
|
The code necessary to make the I2C data line tri-stated
|
|
(inactive). If the data line is open collector, this
|
|
define can be null.
|
|
|
|
eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
|
|
|
|
I2C_READ
|
|
|
|
Code that returns true if the I2C data line is high,
|
|
false if it is low.
|
|
|
|
eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
|
|
|
|
I2C_SDA(bit)
|
|
|
|
If <bit> is true, sets the I2C data line high. If it
|
|
is false, it clears it (low).
|
|
|
|
eg: #define I2C_SDA(bit) \
|
|
if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
|
|
else immr->im_cpm.cp_pbdat &= ~PB_SDA
|
|
|
|
I2C_SCL(bit)
|
|
|
|
If <bit> is true, sets the I2C clock line high. If it
|
|
is false, it clears it (low).
|
|
|
|
eg: #define I2C_SCL(bit) \
|
|
if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
|
|
else immr->im_cpm.cp_pbdat &= ~PB_SCL
|
|
|
|
I2C_DELAY
|
|
|
|
This delay is invoked four times per clock cycle so this
|
|
controls the rate of data transfer. The data rate thus
|
|
is 1 / (I2C_DELAY * 4). Often defined to be something
|
|
like:
|
|
|
|
#define I2C_DELAY udelay(2)
|
|
|
|
CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
|
|
|
|
If your arch supports the generic GPIO framework (asm/gpio.h),
|
|
then you may alternatively define the two GPIOs that are to be
|
|
used as SCL / SDA. Any of the previous I2C_xxx macros will
|
|
have GPIO-based defaults assigned to them as appropriate.
|
|
|
|
You should define these to the GPIO value as given directly to
|
|
the generic GPIO functions.
|
|
|
|
CFG_SYS_I2C_NOPROBES
|
|
|
|
This option specifies a list of I2C devices that will be skipped
|
|
when the 'i2c probe' command is issued.
|
|
|
|
e.g.
|
|
#define CFG_SYS_I2C_NOPROBES {0x50,0x68}
|
|
|
|
will skip addresses 0x50 and 0x68 on a board with one I2C bus
|
|
|
|
CONFIG_SOFT_I2C_READ_REPEATED_START
|
|
|
|
defining this will force the i2c_read() function in
|
|
the soft_i2c driver to perform an I2C repeated start
|
|
between writing the address pointer and reading the
|
|
data. If this define is omitted the default behaviour
|
|
of doing a stop-start sequence will be used. Most I2C
|
|
devices can use either method, but some require one or
|
|
the other.
|
|
|
|
- SPI Support: CONFIG_SPI
|
|
|
|
Enables SPI driver (so far only tested with
|
|
SPI EEPROM, also an instance works with Crystal A/D and
|
|
D/As on the SACSng board)
|
|
|
|
CFG_SYS_SPI_MXC_WAIT
|
|
Timeout for waiting until spi transfer completed.
|
|
default: (CONFIG_SYS_HZ/100) /* 10 ms */
|
|
|
|
- FPGA Support: CONFIG_FPGA
|
|
|
|
Enables FPGA subsystem.
|
|
|
|
CONFIG_FPGA_<vendor>
|
|
|
|
Enables support for specific chip vendors.
|
|
(ALTERA, XILINX)
|
|
|
|
CONFIG_FPGA_<family>
|
|
|
|
Enables support for FPGA family.
|
|
(SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
|
|
|
|
CONFIG_SYS_FPGA_CHECK_BUSY
|
|
|
|
Enable checks on FPGA configuration interface busy
|
|
status by the configuration function. This option
|
|
will require a board or device specific function to
|
|
be written.
|
|
|
|
CFG_FPGA_DELAY
|
|
|
|
If defined, a function that provides delays in the FPGA
|
|
configuration driver.
|
|
|
|
CFG_SYS_FPGA_CHECK_ERROR
|
|
|
|
Check for configuration errors during FPGA bitfile
|
|
loading. For example, abort during Virtex II
|
|
configuration if the INIT_B line goes low (which
|
|
indicated a CRC error).
|
|
|
|
CFG_SYS_FPGA_WAIT_INIT
|
|
|
|
Maximum time to wait for the INIT_B line to de-assert
|
|
after PROB_B has been de-asserted during a Virtex II
|
|
FPGA configuration sequence. The default time is 500
|
|
ms.
|
|
|
|
CFG_SYS_FPGA_WAIT_BUSY
|
|
|
|
Maximum time to wait for BUSY to de-assert during
|
|
Virtex II FPGA configuration. The default is 5 ms.
|
|
|
|
CFG_SYS_FPGA_WAIT_CONFIG
|
|
|
|
Time to wait after FPGA configuration. The default is
|
|
200 ms.
|
|
|
|
- Vendor Parameter Protection:
|
|
|
|
U-Boot considers the values of the environment
|
|
variables "serial#" (Board Serial Number) and
|
|
"ethaddr" (Ethernet Address) to be parameters that
|
|
are set once by the board vendor / manufacturer, and
|
|
protects these variables from casual modification by
|
|
the user. Once set, these variables are read-only,
|
|
and write or delete attempts are rejected. You can
|
|
change this behaviour:
|
|
|
|
If CONFIG_ENV_OVERWRITE is #defined in your config
|
|
file, the write protection for vendor parameters is
|
|
completely disabled. Anybody can change or delete
|
|
these parameters.
|
|
|
|
The same can be accomplished in a more flexible way
|
|
for any variable by configuring the type of access
|
|
to allow for those variables in the ".flags" variable
|
|
or define CFG_ENV_FLAGS_LIST_STATIC.
|
|
|
|
- Protected RAM:
|
|
CFG_PRAM
|
|
|
|
Define this variable to enable the reservation of
|
|
"protected RAM", i. e. RAM which is not overwritten
|
|
by U-Boot. Define CFG_PRAM to hold the number of
|
|
kB you want to reserve for pRAM. You can overwrite
|
|
this default value by defining an environment
|
|
variable "pram" to the number of kB you want to
|
|
reserve. Note that the board info structure will
|
|
still show the full amount of RAM. If pRAM is
|
|
reserved, a new environment variable "mem" will
|
|
automatically be defined to hold the amount of
|
|
remaining RAM in a form that can be passed as boot
|
|
argument to Linux, for instance like that:
|
|
|
|
setenv bootargs ... mem=\${mem}
|
|
saveenv
|
|
|
|
This way you can tell Linux not to use this memory,
|
|
either, which results in a memory region that will
|
|
not be affected by reboots.
|
|
|
|
*WARNING* If your board configuration uses automatic
|
|
detection of the RAM size, you must make sure that
|
|
this memory test is non-destructive. So far, the
|
|
following board configurations are known to be
|
|
"pRAM-clean":
|
|
|
|
IVMS8, IVML24, SPD8xx,
|
|
HERMES, IP860, RPXlite, LWMON,
|
|
FLAGADM
|
|
|
|
- Error Recovery:
|
|
Note:
|
|
|
|
In the current implementation, the local variables
|
|
space and global environment variables space are
|
|
separated. Local variables are those you define by
|
|
simply typing `name=value'. To access a local
|
|
variable later on, you have write `$name' or
|
|
`${name}'; to execute the contents of a variable
|
|
directly type `$name' at the command prompt.
|
|
|
|
Global environment variables are those you use
|
|
setenv/printenv to work with. To run a command stored
|
|
in such a variable, you need to use the run command,
|
|
and you must not use the '$' sign to access them.
|
|
|
|
To store commands and special characters in a
|
|
variable, please use double quotation marks
|
|
surrounding the whole text of the variable, instead
|
|
of the backslashes before semicolons and special
|
|
symbols.
|
|
|
|
- Default Environment:
|
|
CFG_EXTRA_ENV_SETTINGS
|
|
|
|
Define this to contain any number of null terminated
|
|
strings (variable = value pairs) that will be part of
|
|
the default environment compiled into the boot image.
|
|
|
|
For example, place something like this in your
|
|
board's config file:
|
|
|
|
#define CFG_EXTRA_ENV_SETTINGS \
|
|
"myvar1=value1\0" \
|
|
"myvar2=value2\0"
|
|
|
|
Warning: This method is based on knowledge about the
|
|
internal format how the environment is stored by the
|
|
U-Boot code. This is NOT an official, exported
|
|
interface! Although it is unlikely that this format
|
|
will change soon, there is no guarantee either.
|
|
You better know what you are doing here.
|
|
|
|
Note: overly (ab)use of the default environment is
|
|
discouraged. Make sure to check other ways to preset
|
|
the environment like the "source" command or the
|
|
boot command first.
|
|
|
|
CONFIG_DELAY_ENVIRONMENT
|
|
|
|
Normally the environment is loaded when the board is
|
|
initialised so that it is available to U-Boot. This inhibits
|
|
that so that the environment is not available until
|
|
explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
|
|
this is instead controlled by the value of
|
|
/config/load-environment.
|
|
|
|
- Automatic software updates via TFTP server
|
|
CONFIG_UPDATE_TFTP
|
|
CONFIG_UPDATE_TFTP_CNT_MAX
|
|
CONFIG_UPDATE_TFTP_MSEC_MAX
|
|
|
|
These options enable and control the auto-update feature;
|
|
for a more detailed description refer to doc/README.update.
|
|
|
|
- MTD Support (mtdparts command, UBI support)
|
|
CONFIG_MTD_UBI_WL_THRESHOLD
|
|
This parameter defines the maximum difference between the highest
|
|
erase counter value and the lowest erase counter value of eraseblocks
|
|
of UBI devices. When this threshold is exceeded, UBI starts performing
|
|
wear leveling by means of moving data from eraseblock with low erase
|
|
counter to eraseblocks with high erase counter.
|
|
|
|
The default value should be OK for SLC NAND flashes, NOR flashes and
|
|
other flashes which have eraseblock life-cycle 100000 or more.
|
|
However, in case of MLC NAND flashes which typically have eraseblock
|
|
life-cycle less than 10000, the threshold should be lessened (e.g.,
|
|
to 128 or 256, although it does not have to be power of 2).
|
|
|
|
default: 4096
|
|
|
|
CONFIG_MTD_UBI_BEB_LIMIT
|
|
This option specifies the maximum bad physical eraseblocks UBI
|
|
expects on the MTD device (per 1024 eraseblocks). If the
|
|
underlying flash does not admit of bad eraseblocks (e.g. NOR
|
|
flash), this value is ignored.
|
|
|
|
NAND datasheets often specify the minimum and maximum NVM
|
|
(Number of Valid Blocks) for the flashes' endurance lifetime.
|
|
The maximum expected bad eraseblocks per 1024 eraseblocks
|
|
then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
|
|
which gives 20 for most NANDs (MaxNVB is basically the total
|
|
count of eraseblocks on the chip).
|
|
|
|
To put it differently, if this value is 20, UBI will try to
|
|
reserve about 1.9% of physical eraseblocks for bad blocks
|
|
handling. And that will be 1.9% of eraseblocks on the entire
|
|
NAND chip, not just the MTD partition UBI attaches. This means
|
|
that if you have, say, a NAND flash chip admits maximum 40 bad
|
|
eraseblocks, and it is split on two MTD partitions of the same
|
|
size, UBI will reserve 40 eraseblocks when attaching a
|
|
partition.
|
|
|
|
default: 20
|
|
|
|
CONFIG_MTD_UBI_FASTMAP
|
|
Fastmap is a mechanism which allows attaching an UBI device
|
|
in nearly constant time. Instead of scanning the whole MTD device it
|
|
only has to locate a checkpoint (called fastmap) on the device.
|
|
The on-flash fastmap contains all information needed to attach
|
|
the device. Using fastmap makes only sense on large devices where
|
|
attaching by scanning takes long. UBI will not automatically install
|
|
a fastmap on old images, but you can set the UBI parameter
|
|
CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
|
|
that fastmap-enabled images are still usable with UBI implementations
|
|
without fastmap support. On typical flash devices the whole fastmap
|
|
fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
|
|
|
|
CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
|
|
Set this parameter to enable fastmap automatically on images
|
|
without a fastmap.
|
|
default: 0
|
|
|
|
CONFIG_MTD_UBI_FM_DEBUG
|
|
Enable UBI fastmap debug
|
|
default: 0
|
|
|
|
- SPL framework
|
|
CONFIG_SPL
|
|
Enable building of SPL globally.
|
|
|
|
CONFIG_SPL_PANIC_ON_RAW_IMAGE
|
|
When defined, SPL will panic() if the image it has
|
|
loaded does not have a signature.
|
|
Defining this is useful when code which loads images
|
|
in SPL cannot guarantee that absolutely all read errors
|
|
will be caught.
|
|
An example is the LPC32XX MLC NAND driver, which will
|
|
consider that a completely unreadable NAND block is bad,
|
|
and thus should be skipped silently.
|
|
|
|
CONFIG_SPL_DISPLAY_PRINT
|
|
For ARM, enable an optional function to print more information
|
|
about the running system.
|
|
|
|
CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
|
|
Set this for NAND SPL on PPC mpc83xx targets, so that
|
|
start.S waits for the rest of the SPL to load before
|
|
continuing (the hardware starts execution after just
|
|
loading the first page rather than the full 4K).
|
|
|
|
CONFIG_SPL_UBI
|
|
Support for a lightweight UBI (fastmap) scanner and
|
|
loader
|
|
|
|
CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_SIZE,
|
|
CONFIG_SYS_NAND_OOBSIZE, CONFIG_SYS_NAND_BLOCK_SIZE,
|
|
CONFIG_SYS_NAND_BAD_BLOCK_POS, CFG_SYS_NAND_ECCPOS,
|
|
CFG_SYS_NAND_ECCSIZE, CFG_SYS_NAND_ECCBYTES
|
|
Defines the size and behavior of the NAND that SPL uses
|
|
to read U-Boot
|
|
|
|
CFG_SYS_NAND_U_BOOT_DST
|
|
Location in memory to load U-Boot to
|
|
|
|
CFG_SYS_NAND_U_BOOT_SIZE
|
|
Size of image to load
|
|
|
|
CFG_SYS_NAND_U_BOOT_START
|
|
Entry point in loaded image to jump to
|
|
|
|
CONFIG_SPL_RAM_DEVICE
|
|
Support for running image already present in ram, in SPL binary
|
|
|
|
CONFIG_SPL_FIT_PRINT
|
|
Printing information about a FIT image adds quite a bit of
|
|
code to SPL. So this is normally disabled in SPL. Use this
|
|
option to re-enable it. This will affect the output of the
|
|
bootm command when booting a FIT image.
|
|
|
|
- Interrupt support (PPC):
|
|
|
|
There are common interrupt_init() and timer_interrupt()
|
|
for all PPC archs. interrupt_init() calls interrupt_init_cpu()
|
|
for CPU specific initialization. interrupt_init_cpu()
|
|
should set decrementer_count to appropriate value. If
|
|
CPU resets decrementer automatically after interrupt
|
|
(ppc4xx) it should set decrementer_count to zero.
|
|
timer_interrupt() calls timer_interrupt_cpu() for CPU
|
|
specific handling. If board has watchdog / status_led
|
|
/ other_activity_monitor it works automatically from
|
|
general timer_interrupt().
|
|
|
|
|
|
Board initialization settings:
|
|
------------------------------
|
|
|
|
During Initialization u-boot calls a number of board specific functions
|
|
to allow the preparation of board specific prerequisites, e.g. pin setup
|
|
before drivers are initialized. To enable these callbacks the
|
|
following configuration macros have to be defined. Currently this is
|
|
architecture specific, so please check arch/your_architecture/lib/board.c
|
|
typically in board_init_f() and board_init_r().
|
|
|
|
- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
|
|
- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
|
|
- CONFIG_BOARD_LATE_INIT: Call board_late_init()
|
|
|
|
Configuration Settings:
|
|
-----------------------
|
|
|
|
- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
|
|
undefine this when you're short of memory.
|
|
|
|
- CFG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
|
|
width of the commands listed in the 'help' command output.
|
|
|
|
- CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
|
|
prompt for user input.
|
|
|
|
- CFG_SYS_BAUDRATE_TABLE:
|
|
List of legal baudrate settings for this board.
|
|
|
|
- CFG_SYS_MEM_RESERVE_SECURE
|
|
Only implemented for ARMv8 for now.
|
|
If defined, the size of CFG_SYS_MEM_RESERVE_SECURE memory
|
|
is substracted from total RAM and won't be reported to OS.
|
|
This memory can be used as secure memory. A variable
|
|
gd->arch.secure_ram is used to track the location. In systems
|
|
the RAM base is not zero, or RAM is divided into banks,
|
|
this variable needs to be recalcuated to get the address.
|
|
|
|
- CFG_SYS_SDRAM_BASE:
|
|
Physical start address of SDRAM. _Must_ be 0 here.
|
|
|
|
- CFG_SYS_FLASH_BASE:
|
|
Physical start address of Flash memory.
|
|
|
|
- CONFIG_SYS_MALLOC_LEN:
|
|
Size of DRAM reserved for malloc() use.
|
|
|
|
- CFG_SYS_BOOTMAPSZ:
|
|
Maximum size of memory mapped by the startup code of
|
|
the Linux kernel; all data that must be processed by
|
|
the Linux kernel (bd_info, boot arguments, FDT blob if
|
|
used) must be put below this limit, unless "bootm_low"
|
|
environment variable is defined and non-zero. In such case
|
|
all data for the Linux kernel must be between "bootm_low"
|
|
and "bootm_low" + CFG_SYS_BOOTMAPSZ. The environment
|
|
variable "bootm_mapsize" will override the value of
|
|
CFG_SYS_BOOTMAPSZ. If CFG_SYS_BOOTMAPSZ is undefined,
|
|
then the value in "bootm_size" will be used instead.
|
|
|
|
- CONFIG_SYS_BOOT_GET_CMDLINE:
|
|
Enables allocating and saving kernel cmdline in space between
|
|
"bootm_low" and "bootm_low" + BOOTMAPSZ.
|
|
|
|
- CONFIG_SYS_BOOT_GET_KBD:
|
|
Enables allocating and saving a kernel copy of the bd_info in
|
|
space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
|
|
|
|
- CONFIG_SYS_FLASH_PROTECTION
|
|
If defined, hardware flash sectors protection is used
|
|
instead of U-Boot software protection.
|
|
|
|
- CONFIG_SYS_FLASH_CFI:
|
|
Define if the flash driver uses extra elements in the
|
|
common flash structure for storing flash geometry.
|
|
|
|
- CONFIG_FLASH_CFI_DRIVER
|
|
This option also enables the building of the cfi_flash driver
|
|
in the drivers directory
|
|
|
|
- CONFIG_FLASH_CFI_MTD
|
|
This option enables the building of the cfi_mtd driver
|
|
in the drivers directory. The driver exports CFI flash
|
|
to the MTD layer.
|
|
|
|
- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
|
|
Use buffered writes to flash.
|
|
|
|
- CONFIG_ENV_FLAGS_LIST_DEFAULT
|
|
- CFG_ENV_FLAGS_LIST_STATIC
|
|
Enable validation of the values given to environment variables when
|
|
calling env set. Variables can be restricted to only decimal,
|
|
hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
|
|
the variables can also be restricted to IP address or MAC address.
|
|
|
|
The format of the list is:
|
|
type_attribute = [s|d|x|b|i|m]
|
|
access_attribute = [a|r|o|c]
|
|
attributes = type_attribute[access_attribute]
|
|
entry = variable_name[:attributes]
|
|
list = entry[,list]
|
|
|
|
The type attributes are:
|
|
s - String (default)
|
|
d - Decimal
|
|
x - Hexadecimal
|
|
b - Boolean ([1yYtT|0nNfF])
|
|
i - IP address
|
|
m - MAC address
|
|
|
|
The access attributes are:
|
|
a - Any (default)
|
|
r - Read-only
|
|
o - Write-once
|
|
c - Change-default
|
|
|
|
- CONFIG_ENV_FLAGS_LIST_DEFAULT
|
|
Define this to a list (string) to define the ".flags"
|
|
environment variable in the default or embedded environment.
|
|
|
|
- CFG_ENV_FLAGS_LIST_STATIC
|
|
Define this to a list (string) to define validation that
|
|
should be done if an entry is not found in the ".flags"
|
|
environment variable. To override a setting in the static
|
|
list, simply add an entry for the same variable name to the
|
|
".flags" variable.
|
|
|
|
If CONFIG_REGEX is defined, the variable_name above is evaluated as a
|
|
regular expression. This allows multiple variables to define the same
|
|
flags without explicitly listing them for each variable.
|
|
|
|
The following definitions that deal with the placement and management
|
|
of environment data (variable area); in general, we support the
|
|
following configurations:
|
|
|
|
BE CAREFUL! The first access to the environment happens quite early
|
|
in U-Boot initialization (when we try to get the setting of for the
|
|
console baudrate). You *MUST* have mapped your NVRAM area then, or
|
|
U-Boot will hang.
|
|
|
|
Please note that even with NVRAM we still use a copy of the
|
|
environment in RAM: we could work on NVRAM directly, but we want to
|
|
keep settings there always unmodified except somebody uses "saveenv"
|
|
to save the current settings.
|
|
|
|
BE CAREFUL! For some special cases, the local device can not use
|
|
"saveenv" command. For example, the local device will get the
|
|
environment stored in a remote NOR flash by SRIO or PCIE link,
|
|
but it can not erase, write this NOR flash by SRIO or PCIE interface.
|
|
|
|
- CONFIG_NAND_ENV_DST
|
|
|
|
Defines address in RAM to which the nand_spl code should copy the
|
|
environment. If redundant environment is used, it will be copied to
|
|
CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
|
|
|
|
Please note that the environment is read-only until the monitor
|
|
has been relocated to RAM and a RAM copy of the environment has been
|
|
created; also, when using EEPROM you will have to use env_get_f()
|
|
until then to read environment variables.
|
|
|
|
The environment is protected by a CRC32 checksum. Before the monitor
|
|
is relocated into RAM, as a result of a bad CRC you will be working
|
|
with the compiled-in default environment - *silently*!!! [This is
|
|
necessary, because the first environment variable we need is the
|
|
"baudrate" setting for the console - if we have a bad CRC, we don't
|
|
have any device yet where we could complain.]
|
|
|
|
Note: once the monitor has been relocated, then it will complain if
|
|
the default environment is used; a new CRC is computed as soon as you
|
|
use the "saveenv" command to store a valid environment.
|
|
|
|
- CONFIG_SYS_FAULT_MII_ADDR:
|
|
MII address of the PHY to check for the Ethernet link state.
|
|
|
|
- CONFIG_DISPLAY_BOARDINFO
|
|
Display information about the board that U-Boot is running on
|
|
when U-Boot starts up. The board function checkboard() is called
|
|
to do this.
|
|
|
|
- CONFIG_DISPLAY_BOARDINFO_LATE
|
|
Similar to the previous option, but display this information
|
|
later, once stdio is running and output goes to the LCD, if
|
|
present.
|
|
|
|
Low Level (hardware related) configuration options:
|
|
---------------------------------------------------
|
|
|
|
- CONFIG_SYS_CACHELINE_SIZE:
|
|
Cache Line Size of the CPU.
|
|
|
|
- CONFIG_SYS_CCSRBAR_DEFAULT:
|
|
Default (power-on reset) physical address of CCSR on Freescale
|
|
PowerPC SOCs.
|
|
|
|
- CFG_SYS_CCSRBAR:
|
|
Virtual address of CCSR. On a 32-bit build, this is typically
|
|
the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
|
|
|
|
- CFG_SYS_CCSRBAR_PHYS:
|
|
Physical address of CCSR. CCSR can be relocated to a new
|
|
physical address, if desired. In this case, this macro should
|
|
be set to that address. Otherwise, it should be set to the
|
|
same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
|
|
is typically relocated on 36-bit builds. It is recommended
|
|
that this macro be defined via the _HIGH and _LOW macros:
|
|
|
|
#define CFG_SYS_CCSRBAR_PHYS ((CFG_SYS_CCSRBAR_PHYS_HIGH
|
|
* 1ull) << 32 | CFG_SYS_CCSRBAR_PHYS_LOW)
|
|
|
|
- CFG_SYS_CCSRBAR_PHYS_HIGH:
|
|
Bits 33-36 of CFG_SYS_CCSRBAR_PHYS. This value is typically
|
|
either 0 (32-bit build) or 0xF (36-bit build). This macro is
|
|
used in assembly code, so it must not contain typecasts or
|
|
integer size suffixes (e.g. "ULL").
|
|
|
|
- CFG_SYS_CCSRBAR_PHYS_LOW:
|
|
Lower 32-bits of CFG_SYS_CCSRBAR_PHYS. This macro is
|
|
used in assembly code, so it must not contain typecasts or
|
|
integer size suffixes (e.g. "ULL").
|
|
|
|
- CONFIG_SYS_IMMR: Physical address of the Internal Memory.
|
|
DO NOT CHANGE unless you know exactly what you're
|
|
doing! (11-4) [MPC8xx systems only]
|
|
|
|
- CFG_SYS_INIT_RAM_ADDR:
|
|
|
|
Start address of memory area that can be used for
|
|
initial data and stack; please note that this must be
|
|
writable memory that is working WITHOUT special
|
|
initialization, i. e. you CANNOT use normal RAM which
|
|
will become available only after programming the
|
|
memory controller and running certain initialization
|
|
sequences.
|
|
|
|
U-Boot uses the following memory types:
|
|
- MPC8xx: IMMR (internal memory of the CPU)
|
|
|
|
- CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
|
|
|
|
- CONFIG_SYS_OR_TIMING_SDRAM:
|
|
SDRAM timing
|
|
|
|
- CONFIG_SYS_SRIOn_MEM_VIRT:
|
|
Virtual Address of SRIO port 'n' memory region
|
|
|
|
- CONFIG_SYS_SRIOn_MEM_PHYxS:
|
|
Physical Address of SRIO port 'n' memory region
|
|
|
|
- CONFIG_SYS_SRIOn_MEM_SIZE:
|
|
Size of SRIO port 'n' memory region
|
|
|
|
- CONFIG_SYS_NAND_BUSWIDTH_16BIT
|
|
Defined to tell the NAND controller that the NAND chip is using
|
|
a 16 bit bus.
|
|
Not all NAND drivers use this symbol.
|
|
Example of drivers that use it:
|
|
- drivers/mtd/nand/raw/ndfc.c
|
|
- drivers/mtd/nand/raw/mxc_nand.c
|
|
|
|
- CONFIG_SYS_NDFC_EBC0_CFG
|
|
Sets the EBC0_CFG register for the NDFC. If not defined
|
|
a default value will be used.
|
|
|
|
- CONFIG_SYS_SPD_BUS_NUM
|
|
If SPD EEPROM is on an I2C bus other than the first
|
|
one, specify here. Note that the value must resolve
|
|
to something your driver can deal with.
|
|
|
|
- CONFIG_FSL_DDR_INTERACTIVE
|
|
Enable interactive DDR debugging. See doc/README.fsl-ddr.
|
|
|
|
- CONFIG_FSL_DDR_SYNC_REFRESH
|
|
Enable sync of refresh for multiple controllers.
|
|
|
|
- CONFIG_FSL_DDR_BIST
|
|
Enable built-in memory test for Freescale DDR controllers.
|
|
|
|
- CONFIG_RMII
|
|
Enable RMII mode for all FECs.
|
|
Note that this is a global option, we can't
|
|
have one FEC in standard MII mode and another in RMII mode.
|
|
|
|
- CONFIG_CRC32_VERIFY
|
|
Add a verify option to the crc32 command.
|
|
The syntax is:
|
|
|
|
=> crc32 -v <address> <count> <crc32>
|
|
|
|
Where address/count indicate a memory area
|
|
and crc32 is the correct crc32 which the
|
|
area should have.
|
|
|
|
- CONFIG_LOOPW
|
|
Add the "loopw" memory command. This only takes effect if
|
|
the memory commands are activated globally (CONFIG_CMD_MEMORY).
|
|
|
|
- CONFIG_CMD_MX_CYCLIC
|
|
Add the "mdc" and "mwc" memory commands. These are cyclic
|
|
"md/mw" commands.
|
|
Examples:
|
|
|
|
=> mdc.b 10 4 500
|
|
This command will print 4 bytes (10,11,12,13) each 500 ms.
|
|
|
|
=> mwc.l 100 12345678 10
|
|
This command will write 12345678 to address 100 all 10 ms.
|
|
|
|
This only takes effect if the memory commands are activated
|
|
globally (CONFIG_CMD_MEMORY).
|
|
|
|
- CONFIG_XPL_BUILD
|
|
Set when the currently running compilation is for an artifact
|
|
that will end up in one of the 'xPL' builds, i.e. SPL, TPL or
|
|
VPL. Code that needs phase-specific behaviour can check this,
|
|
or (where possible) use xpl_phase() instead.
|
|
|
|
Note that CONFIG_XPL_BUILD *is* always defined when either
|
|
of CONFIG_TPL_BUILD / CONFIG_VPL_BUILD is defined. This can be
|
|
counter-intuitive and should perhaps be changed.
|
|
|
|
- CONFIG_TPL_BUILD
|
|
Set when the currently running compilation is for an artifact
|
|
that will end up in the TPL build (as opposed to SPL, VPL or
|
|
U-Boot proper). Code that needs phase-specific behaviour can
|
|
check this, or (where possible) use xpl_phase() instead.
|
|
|
|
- CONFIG_VPL_BUILD
|
|
Set when the currently running compilation is for an artifact
|
|
that will end up in the VPL build (as opposed to the SPL, TPL
|
|
or U-Boot proper). Code that needs phase-specific behaviour can
|
|
check this, or (where possible) use xpl_phase() instead.
|
|
|
|
- CONFIG_ARCH_MAP_SYSMEM
|
|
Generally U-Boot (and in particular the md command) uses
|
|
effective address. It is therefore not necessary to regard
|
|
U-Boot address as virtual addresses that need to be translated
|
|
to physical addresses. However, sandbox requires this, since
|
|
it maintains its own little RAM buffer which contains all
|
|
addressable memory. This option causes some memory accesses
|
|
to be mapped through map_sysmem() / unmap_sysmem().
|
|
|
|
- CONFIG_X86_RESET_VECTOR
|
|
If defined, the x86 reset vector code is included. This is not
|
|
needed when U-Boot is running from Coreboot.
|
|
|
|
Freescale QE/FMAN Firmware Support:
|
|
-----------------------------------
|
|
|
|
The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
|
|
loading of "firmware", which is encoded in the QE firmware binary format.
|
|
This firmware often needs to be loaded during U-Boot booting, so macros
|
|
are used to identify the storage device (NOR flash, SPI, etc) and the address
|
|
within that device.
|
|
|
|
- CONFIG_SYS_FMAN_FW_ADDR
|
|
The address in the storage device where the FMAN microcode is located. The
|
|
meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
|
|
is also specified.
|
|
|
|
- CONFIG_SYS_QE_FW_ADDR
|
|
The address in the storage device where the QE microcode is located. The
|
|
meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
|
|
is also specified.
|
|
|
|
- CONFIG_SYS_QE_FMAN_FW_LENGTH
|
|
The maximum possible size of the firmware. The firmware binary format
|
|
has a field that specifies the actual size of the firmware, but it
|
|
might not be possible to read any part of the firmware unless some
|
|
local storage is allocated to hold the entire firmware first.
|
|
|
|
- CONFIG_SYS_QE_FMAN_FW_IN_NOR
|
|
Specifies that QE/FMAN firmware is located in NOR flash, mapped as
|
|
normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
|
|
virtual address in NOR flash.
|
|
|
|
- CONFIG_SYS_QE_FMAN_FW_IN_NAND
|
|
Specifies that QE/FMAN firmware is located in NAND flash.
|
|
CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
|
|
|
|
- CONFIG_SYS_QE_FMAN_FW_IN_MMC
|
|
Specifies that QE/FMAN firmware is located on the primary SD/MMC
|
|
device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
|
|
|
|
- CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
|
|
Specifies that QE/FMAN firmware is located in the remote (master)
|
|
memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
|
|
can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
|
|
window->master inbound window->master LAW->the ucode address in
|
|
master's memory space.
|
|
|
|
Freescale Layerscape Management Complex Firmware Support:
|
|
---------------------------------------------------------
|
|
The Freescale Layerscape Management Complex (MC) supports the loading of
|
|
"firmware".
|
|
This firmware often needs to be loaded during U-Boot booting, so macros
|
|
are used to identify the storage device (NOR flash, SPI, etc) and the address
|
|
within that device.
|
|
|
|
- CONFIG_FSL_MC_ENET
|
|
Enable the MC driver for Layerscape SoCs.
|
|
|
|
Freescale Layerscape Debug Server Support:
|
|
-------------------------------------------
|
|
The Freescale Layerscape Debug Server Support supports the loading of
|
|
"Debug Server firmware" and triggering SP boot-rom.
|
|
This firmware often needs to be loaded during U-Boot booting.
|
|
|
|
- CONFIG_SYS_MC_RSV_MEM_ALIGN
|
|
Define alignment of reserved memory MC requires
|
|
|
|
|
|
Building the Software:
|
|
======================
|
|
|
|
Building U-Boot has been tested in several native build environments
|
|
and in many different cross environments. Of course we cannot support
|
|
all possibly existing versions of cross development tools in all
|
|
(potentially obsolete) versions. In case of tool chain problems we
|
|
recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
|
|
which is extensively used to build and test U-Boot.
|
|
|
|
If you are not using a native environment, it is assumed that you
|
|
have GNU cross compiling tools available in your path. In this case,
|
|
you must set the environment variable CROSS_COMPILE in your shell.
|
|
Note that no changes to the Makefile or any other source files are
|
|
necessary. For example using the ELDK on a 4xx CPU, please enter:
|
|
|
|
$ CROSS_COMPILE=ppc_4xx-
|
|
$ export CROSS_COMPILE
|
|
|
|
U-Boot is intended to be simple to build. After installing the
|
|
sources you must configure U-Boot for one specific board type. This
|
|
is done by typing:
|
|
|
|
make NAME_defconfig
|
|
|
|
where "NAME_defconfig" is the name of one of the existing configu-
|
|
rations; see configs/*_defconfig for supported names.
|
|
|
|
Note: for some boards special configuration names may exist; check if
|
|
additional information is available from the board vendor; for
|
|
instance, the TQM823L systems are available without (standard)
|
|
or with LCD support. You can select such additional "features"
|
|
when choosing the configuration, i. e.
|
|
|
|
make TQM823L_defconfig
|
|
- will configure for a plain TQM823L, i. e. no LCD support
|
|
|
|
make TQM823L_LCD_defconfig
|
|
- will configure for a TQM823L with U-Boot console on LCD
|
|
|
|
etc.
|
|
|
|
|
|
Finally, type "make all", and you should get some working U-Boot
|
|
images ready for download to / installation on your system:
|
|
|
|
- "u-boot.bin" is a raw binary image
|
|
- "u-boot" is an image in ELF binary format
|
|
- "u-boot.srec" is in Motorola S-Record format
|
|
|
|
User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
|
|
setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
|
|
For example to treat all compiler warnings as errors:
|
|
|
|
make KCFLAGS=-Werror
|
|
|
|
Please be aware that the Makefiles assume you are using GNU make, so
|
|
for instance on NetBSD you might need to use "gmake" instead of
|
|
native "make".
|
|
|
|
|
|
If the system board that you have is not listed, then you will need
|
|
to port U-Boot to your hardware platform. To do this, follow these
|
|
steps:
|
|
|
|
1. Create a new directory to hold your board specific code. Add any
|
|
files you need. In your board directory, you will need at least
|
|
the "Makefile" and a "<board>.c".
|
|
2. Create a new configuration file "include/configs/<board>.h" for
|
|
your board.
|
|
3. If you're porting U-Boot to a new CPU, then also create a new
|
|
directory to hold your CPU specific code. Add any files you need.
|
|
4. Run "make <board>_defconfig" with your new name.
|
|
5. Type "make", and you should get a working "u-boot.srec" file
|
|
to be installed on your target system.
|
|
6. Debug and solve any problems that might arise.
|
|
[Of course, this last step is much harder than it sounds.]
|
|
|
|
|
|
Testing of U-Boot Modifications, Ports to New Hardware, etc.:
|
|
==============================================================
|
|
|
|
If you have modified U-Boot sources (for instance added a new board
|
|
or support for new devices, a new CPU, etc.) you are expected to
|
|
provide feedback to the other developers. The feedback normally takes
|
|
the form of a "patch", i.e. a context diff against a certain (latest
|
|
official or latest in the git repository) version of U-Boot sources.
|
|
|
|
But before you submit such a patch, please verify that your modifi-
|
|
cation did not break existing code. At least make sure that *ALL* of
|
|
the supported boards compile WITHOUT ANY compiler warnings. To do so,
|
|
just run the buildman script (tools/buildman/buildman), which will
|
|
configure and build U-Boot for ALL supported system. Be warned, this
|
|
will take a while. Please see the buildman README, or run 'buildman -H'
|
|
for documentation.
|
|
|
|
|
|
See also "U-Boot Porting Guide" below.
|
|
|
|
|
|
Monitor Commands - Overview:
|
|
============================
|
|
|
|
go - start application at address 'addr'
|
|
run - run commands in an environment variable
|
|
bootm - boot application image from memory
|
|
bootp - boot image via network using BootP/TFTP protocol
|
|
bootz - boot zImage from memory
|
|
tftpboot- boot image via network using TFTP protocol
|
|
and env variables "ipaddr" and "serverip"
|
|
(and eventually "gatewayip")
|
|
tftpput - upload a file via network using TFTP protocol
|
|
rarpboot- boot image via network using RARP/TFTP protocol
|
|
diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
|
|
loads - load S-Record file over serial line
|
|
loadb - load binary file over serial line (kermit mode)
|
|
loadm - load binary blob from source address to destination address
|
|
md - memory display
|
|
mm - memory modify (auto-incrementing)
|
|
nm - memory modify (constant address)
|
|
mw - memory write (fill)
|
|
ms - memory search
|
|
cp - memory copy
|
|
cmp - memory compare
|
|
crc32 - checksum calculation
|
|
i2c - I2C sub-system
|
|
sspi - SPI utility commands
|
|
base - print or set address offset
|
|
printenv- print environment variables
|
|
pwm - control pwm channels
|
|
seama - load SEAMA NAND image
|
|
setenv - set environment variables
|
|
saveenv - save environment variables to persistent storage
|
|
protect - enable or disable FLASH write protection
|
|
erase - erase FLASH memory
|
|
flinfo - print FLASH memory information
|
|
nand - NAND memory operations (see doc/README.nand)
|
|
bdinfo - print Board Info structure
|
|
iminfo - print header information for application image
|
|
coninfo - print console devices and informations
|
|
ide - IDE sub-system
|
|
loop - infinite loop on address range
|
|
loopw - infinite write loop on address range
|
|
mtest - simple RAM test
|
|
icache - enable or disable instruction cache
|
|
dcache - enable or disable data cache
|
|
reset - Perform RESET of the CPU
|
|
echo - echo args to console
|
|
version - print monitor version
|
|
help - print online help
|
|
? - alias for 'help'
|
|
|
|
|
|
Monitor Commands - Detailed Description:
|
|
========================================
|
|
|
|
TODO.
|
|
|
|
For now: just type "help <command>".
|
|
|
|
|
|
Note for Redundant Ethernet Interfaces:
|
|
=======================================
|
|
|
|
Some boards come with redundant Ethernet interfaces; U-Boot supports
|
|
such configurations and is capable of automatic selection of a
|
|
"working" interface when needed. MAC assignment works as follows:
|
|
|
|
Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
|
|
MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
|
|
"eth1addr" (=>eth1), "eth2addr", ...
|
|
|
|
If the network interface stores some valid MAC address (for instance
|
|
in SROM), this is used as default address if there is NO correspon-
|
|
ding setting in the environment; if the corresponding environment
|
|
variable is set, this overrides the settings in the card; that means:
|
|
|
|
o If the SROM has a valid MAC address, and there is no address in the
|
|
environment, the SROM's address is used.
|
|
|
|
o If there is no valid address in the SROM, and a definition in the
|
|
environment exists, then the value from the environment variable is
|
|
used.
|
|
|
|
o If both the SROM and the environment contain a MAC address, and
|
|
both addresses are the same, this MAC address is used.
|
|
|
|
o If both the SROM and the environment contain a MAC address, and the
|
|
addresses differ, the value from the environment is used and a
|
|
warning is printed.
|
|
|
|
o If neither SROM nor the environment contain a MAC address, an error
|
|
is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
|
|
a random, locally-assigned MAC is used.
|
|
|
|
If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
|
|
will be programmed into hardware as part of the initialization process. This
|
|
may be skipped by setting the appropriate 'ethmacskip' environment variable.
|
|
The naming convention is as follows:
|
|
"ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
|
|
|
|
Image Formats:
|
|
==============
|
|
|
|
U-Boot is capable of booting (and performing other auxiliary operations on)
|
|
images in two formats:
|
|
|
|
New uImage format (FIT)
|
|
-----------------------
|
|
|
|
Flexible and powerful format based on Flattened Image Tree -- FIT (similar
|
|
to Flattened Device Tree). It allows the use of images with multiple
|
|
components (several kernels, ramdisks, etc.), with contents protected by
|
|
SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
|
|
|
|
|
|
Old uImage format
|
|
-----------------
|
|
|
|
Old image format is based on binary files which can be basically anything,
|
|
preceded by a special header; see the definitions in include/image.h for
|
|
details; basically, the header defines the following image properties:
|
|
|
|
* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
|
|
4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
|
|
LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
|
|
Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
|
|
* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
|
|
IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
|
|
Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
|
|
* Compression Type (uncompressed, gzip, bzip2)
|
|
* Load Address
|
|
* Entry Point
|
|
* Image Name
|
|
* Image Timestamp
|
|
|
|
The header is marked by a special Magic Number, and both the header
|
|
and the data portions of the image are secured against corruption by
|
|
CRC32 checksums.
|
|
|
|
|
|
Linux Support:
|
|
==============
|
|
|
|
Although U-Boot should support any OS or standalone application
|
|
easily, the main focus has always been on Linux during the design of
|
|
U-Boot.
|
|
|
|
U-Boot includes many features that so far have been part of some
|
|
special "boot loader" code within the Linux kernel. Also, any
|
|
"initrd" images to be used are no longer part of one big Linux image;
|
|
instead, kernel and "initrd" are separate images. This implementation
|
|
serves several purposes:
|
|
|
|
- the same features can be used for other OS or standalone
|
|
applications (for instance: using compressed images to reduce the
|
|
Flash memory footprint)
|
|
|
|
- it becomes much easier to port new Linux kernel versions because
|
|
lots of low-level, hardware dependent stuff are done by U-Boot
|
|
|
|
- the same Linux kernel image can now be used with different "initrd"
|
|
images; of course this also means that different kernel images can
|
|
be run with the same "initrd". This makes testing easier (you don't
|
|
have to build a new "zImage.initrd" Linux image when you just
|
|
change a file in your "initrd"). Also, a field-upgrade of the
|
|
software is easier now.
|
|
|
|
|
|
Linux HOWTO:
|
|
============
|
|
|
|
Porting Linux to U-Boot based systems:
|
|
---------------------------------------
|
|
|
|
U-Boot cannot save you from doing all the necessary modifications to
|
|
configure the Linux device drivers for use with your target hardware
|
|
(no, we don't intend to provide a full virtual machine interface to
|
|
Linux :-).
|
|
|
|
But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
|
|
|
|
Just make sure your machine specific header file (for instance
|
|
include/asm-ppc/tqm8xx.h) includes the same definition of the Board
|
|
Information structure as we define in include/asm-<arch>/u-boot.h,
|
|
and make sure that your definition of IMAP_ADDR uses the same value
|
|
as your U-Boot configuration in CONFIG_SYS_IMMR.
|
|
|
|
Note that U-Boot now has a driver model, a unified model for drivers.
|
|
If you are adding a new driver, plumb it into driver model. If there
|
|
is no uclass available, you are encouraged to create one. See
|
|
doc/driver-model.
|
|
|
|
|
|
Configuring the Linux kernel:
|
|
-----------------------------
|
|
|
|
No specific requirements for U-Boot. Make sure you have some root
|
|
device (initial ramdisk, NFS) for your target system.
|
|
|
|
|
|
Building a Linux Image:
|
|
-----------------------
|
|
|
|
With U-Boot, "normal" build targets like "zImage" or "bzImage" are
|
|
not used. If you use recent kernel source, a new build target
|
|
"uImage" will exist which automatically builds an image usable by
|
|
U-Boot. Most older kernels also have support for a "pImage" target,
|
|
which was introduced for our predecessor project PPCBoot and uses a
|
|
100% compatible format.
|
|
|
|
Example:
|
|
|
|
make TQM850L_defconfig
|
|
make oldconfig
|
|
make dep
|
|
make uImage
|
|
|
|
The "uImage" build target uses a special tool (in 'tools/mkimage') to
|
|
encapsulate a compressed Linux kernel image with header information,
|
|
CRC32 checksum etc. for use with U-Boot. This is what we are doing:
|
|
|
|
* build a standard "vmlinux" kernel image (in ELF binary format):
|
|
|
|
* convert the kernel into a raw binary image:
|
|
|
|
${CROSS_COMPILE}-objcopy -O binary \
|
|
-R .note -R .comment \
|
|
-S vmlinux linux.bin
|
|
|
|
* compress the binary image:
|
|
|
|
gzip -9 linux.bin
|
|
|
|
* package compressed binary image for U-Boot:
|
|
|
|
mkimage -A ppc -O linux -T kernel -C gzip \
|
|
-a 0 -e 0 -n "Linux Kernel Image" \
|
|
-d linux.bin.gz uImage
|
|
|
|
|
|
The "mkimage" tool can also be used to create ramdisk images for use
|
|
with U-Boot, either separated from the Linux kernel image, or
|
|
combined into one file. "mkimage" encapsulates the images with a 64
|
|
byte header containing information about target architecture,
|
|
operating system, image type, compression method, entry points, time
|
|
stamp, CRC32 checksums, etc.
|
|
|
|
"mkimage" can be called in two ways: to verify existing images and
|
|
print the header information, or to build new images.
|
|
|
|
In the first form (with "-l" option) mkimage lists the information
|
|
contained in the header of an existing U-Boot image; this includes
|
|
checksum verification:
|
|
|
|
tools/mkimage -l image
|
|
-l ==> list image header information
|
|
|
|
The second form (with "-d" option) is used to build a U-Boot image
|
|
from a "data file" which is used as image payload:
|
|
|
|
tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
|
|
-n name -d data_file image
|
|
-A ==> set architecture to 'arch'
|
|
-O ==> set operating system to 'os'
|
|
-T ==> set image type to 'type'
|
|
-C ==> set compression type 'comp'
|
|
-a ==> set load address to 'addr' (hex)
|
|
-e ==> set entry point to 'ep' (hex)
|
|
-n ==> set image name to 'name'
|
|
-d ==> use image data from 'datafile'
|
|
|
|
Right now, all Linux kernels for PowerPC systems use the same load
|
|
address (0x00000000), but the entry point address depends on the
|
|
kernel version:
|
|
|
|
- 2.2.x kernels have the entry point at 0x0000000C,
|
|
- 2.3.x and later kernels have the entry point at 0x00000000.
|
|
|
|
So a typical call to build a U-Boot image would read:
|
|
|
|
-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
|
|
> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
|
|
> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
|
|
> examples/uImage.TQM850L
|
|
Image Name: 2.4.4 kernel for TQM850L
|
|
Created: Wed Jul 19 02:34:59 2000
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
|
|
Load Address: 0x00000000
|
|
Entry Point: 0x00000000
|
|
|
|
To verify the contents of the image (or check for corruption):
|
|
|
|
-> tools/mkimage -l examples/uImage.TQM850L
|
|
Image Name: 2.4.4 kernel for TQM850L
|
|
Created: Wed Jul 19 02:34:59 2000
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
|
|
Load Address: 0x00000000
|
|
Entry Point: 0x00000000
|
|
|
|
NOTE: for embedded systems where boot time is critical you can trade
|
|
speed for memory and install an UNCOMPRESSED image instead: this
|
|
needs more space in Flash, but boots much faster since it does not
|
|
need to be uncompressed:
|
|
|
|
-> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
|
|
-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
|
|
> -A ppc -O linux -T kernel -C none -a 0 -e 0 \
|
|
> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
|
|
> examples/uImage.TQM850L-uncompressed
|
|
Image Name: 2.4.4 kernel for TQM850L
|
|
Created: Wed Jul 19 02:34:59 2000
|
|
Image Type: PowerPC Linux Kernel Image (uncompressed)
|
|
Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
|
|
Load Address: 0x00000000
|
|
Entry Point: 0x00000000
|
|
|
|
|
|
Similar you can build U-Boot images from a 'ramdisk.image.gz' file
|
|
when your kernel is intended to use an initial ramdisk:
|
|
|
|
-> tools/mkimage -n 'Simple Ramdisk Image' \
|
|
> -A ppc -O linux -T ramdisk -C gzip \
|
|
> -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
|
|
Image Name: Simple Ramdisk Image
|
|
Created: Wed Jan 12 14:01:50 2000
|
|
Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
|
|
Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
|
|
Load Address: 0x00000000
|
|
Entry Point: 0x00000000
|
|
|
|
The "dumpimage" tool can be used to disassemble or list the contents of images
|
|
built by mkimage. See dumpimage's help output (-h) for details.
|
|
|
|
Installing a Linux Image:
|
|
-------------------------
|
|
|
|
To downloading a U-Boot image over the serial (console) interface,
|
|
you must convert the image to S-Record format:
|
|
|
|
objcopy -I binary -O srec examples/image examples/image.srec
|
|
|
|
The 'objcopy' does not understand the information in the U-Boot
|
|
image header, so the resulting S-Record file will be relative to
|
|
address 0x00000000. To load it to a given address, you need to
|
|
specify the target address as 'offset' parameter with the 'loads'
|
|
command.
|
|
|
|
Example: install the image to address 0x40100000 (which on the
|
|
TQM8xxL is in the first Flash bank):
|
|
|
|
=> erase 40100000 401FFFFF
|
|
|
|
.......... done
|
|
Erased 8 sectors
|
|
|
|
=> loads 40100000
|
|
## Ready for S-Record download ...
|
|
~>examples/image.srec
|
|
1 2 3 4 5 6 7 8 9 10 11 12 13 ...
|
|
...
|
|
15989 15990 15991 15992
|
|
[file transfer complete]
|
|
[connected]
|
|
## Start Addr = 0x00000000
|
|
|
|
|
|
You can check the success of the download using the 'iminfo' command;
|
|
this includes a checksum verification so you can be sure no data
|
|
corruption happened:
|
|
|
|
=> imi 40100000
|
|
|
|
## Checking Image at 40100000 ...
|
|
Image Name: 2.2.13 for initrd on TQM850L
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 335725 Bytes = 327 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 0000000c
|
|
Verifying Checksum ... OK
|
|
|
|
|
|
Boot Linux:
|
|
-----------
|
|
|
|
The "bootm" command is used to boot an application that is stored in
|
|
memory (RAM or Flash). In case of a Linux kernel image, the contents
|
|
of the "bootargs" environment variable is passed to the kernel as
|
|
parameters. You can check and modify this variable using the
|
|
"printenv" and "setenv" commands:
|
|
|
|
|
|
=> printenv bootargs
|
|
bootargs=root=/dev/ram
|
|
|
|
=> setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
|
|
|
|
=> printenv bootargs
|
|
bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
|
|
|
|
=> bootm 40020000
|
|
## Booting Linux kernel at 40020000 ...
|
|
Image Name: 2.2.13 for NFS on TQM850L
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 381681 Bytes = 372 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 0000000c
|
|
Verifying Checksum ... OK
|
|
Uncompressing Kernel Image ... OK
|
|
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
|
|
Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
|
|
time_init: decrementer frequency = 187500000/60
|
|
Calibrating delay loop... 49.77 BogoMIPS
|
|
Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
|
|
...
|
|
|
|
If you want to boot a Linux kernel with initial RAM disk, you pass
|
|
the memory addresses of both the kernel and the initrd image (PPBCOOT
|
|
format!) to the "bootm" command:
|
|
|
|
=> imi 40100000 40200000
|
|
|
|
## Checking Image at 40100000 ...
|
|
Image Name: 2.2.13 for initrd on TQM850L
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 335725 Bytes = 327 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 0000000c
|
|
Verifying Checksum ... OK
|
|
|
|
## Checking Image at 40200000 ...
|
|
Image Name: Simple Ramdisk Image
|
|
Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
|
|
Data Size: 566530 Bytes = 553 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 00000000
|
|
Verifying Checksum ... OK
|
|
|
|
=> bootm 40100000 40200000
|
|
## Booting Linux kernel at 40100000 ...
|
|
Image Name: 2.2.13 for initrd on TQM850L
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 335725 Bytes = 327 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 0000000c
|
|
Verifying Checksum ... OK
|
|
Uncompressing Kernel Image ... OK
|
|
## Loading RAMDisk Image at 40200000 ...
|
|
Image Name: Simple Ramdisk Image
|
|
Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
|
|
Data Size: 566530 Bytes = 553 kB = 0 MB
|
|
Load Address: 00000000
|
|
Entry Point: 00000000
|
|
Verifying Checksum ... OK
|
|
Loading Ramdisk ... OK
|
|
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
|
|
Boot arguments: root=/dev/ram
|
|
time_init: decrementer frequency = 187500000/60
|
|
Calibrating delay loop... 49.77 BogoMIPS
|
|
...
|
|
RAMDISK: Compressed image found at block 0
|
|
VFS: Mounted root (ext2 filesystem).
|
|
|
|
bash#
|
|
|
|
Boot Linux and pass a flat device tree:
|
|
-----------
|
|
|
|
First, U-Boot must be compiled with the appropriate defines. See the section
|
|
titled "Linux Kernel Interface" above for a more in depth explanation. The
|
|
following is an example of how to start a kernel and pass an updated
|
|
flat device tree:
|
|
|
|
=> print oftaddr
|
|
oftaddr=0x300000
|
|
=> print oft
|
|
oft=oftrees/mpc8540ads.dtb
|
|
=> tftp $oftaddr $oft
|
|
Speed: 1000, full duplex
|
|
Using TSEC0 device
|
|
TFTP from server 192.168.1.1; our IP address is 192.168.1.101
|
|
Filename 'oftrees/mpc8540ads.dtb'.
|
|
Load address: 0x300000
|
|
Loading: #
|
|
done
|
|
Bytes transferred = 4106 (100a hex)
|
|
=> tftp $loadaddr $bootfile
|
|
Speed: 1000, full duplex
|
|
Using TSEC0 device
|
|
TFTP from server 192.168.1.1; our IP address is 192.168.1.2
|
|
Filename 'uImage'.
|
|
Load address: 0x200000
|
|
Loading:############
|
|
done
|
|
Bytes transferred = 1029407 (fb51f hex)
|
|
=> print loadaddr
|
|
loadaddr=200000
|
|
=> print oftaddr
|
|
oftaddr=0x300000
|
|
=> bootm $loadaddr - $oftaddr
|
|
## Booting image at 00200000 ...
|
|
Image Name: Linux-2.6.17-dirty
|
|
Image Type: PowerPC Linux Kernel Image (gzip compressed)
|
|
Data Size: 1029343 Bytes = 1005.2 kB
|
|
Load Address: 00000000
|
|
Entry Point: 00000000
|
|
Verifying Checksum ... OK
|
|
Uncompressing Kernel Image ... OK
|
|
Booting using flat device tree at 0x300000
|
|
Using MPC85xx ADS machine description
|
|
Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
|
|
[snip]
|
|
|
|
|
|
More About U-Boot Image Types:
|
|
------------------------------
|
|
|
|
U-Boot supports the following image types:
|
|
|
|
"Standalone Programs" are directly runnable in the environment
|
|
provided by U-Boot; it is expected that (if they behave
|
|
well) you can continue to work in U-Boot after return from
|
|
the Standalone Program.
|
|
"OS Kernel Images" are usually images of some Embedded OS which
|
|
will take over control completely. Usually these programs
|
|
will install their own set of exception handlers, device
|
|
drivers, set up the MMU, etc. - this means, that you cannot
|
|
expect to re-enter U-Boot except by resetting the CPU.
|
|
"RAMDisk Images" are more or less just data blocks, and their
|
|
parameters (address, size) are passed to an OS kernel that is
|
|
being started.
|
|
"Multi-File Images" contain several images, typically an OS
|
|
(Linux) kernel image and one or more data images like
|
|
RAMDisks. This construct is useful for instance when you want
|
|
to boot over the network using BOOTP etc., where the boot
|
|
server provides just a single image file, but you want to get
|
|
for instance an OS kernel and a RAMDisk image.
|
|
|
|
"Multi-File Images" start with a list of image sizes, each
|
|
image size (in bytes) specified by an "uint32_t" in network
|
|
byte order. This list is terminated by an "(uint32_t)0".
|
|
Immediately after the terminating 0 follow the images, one by
|
|
one, all aligned on "uint32_t" boundaries (size rounded up to
|
|
a multiple of 4 bytes).
|
|
|
|
"Firmware Images" are binary images containing firmware (like
|
|
U-Boot or FPGA images) which usually will be programmed to
|
|
flash memory.
|
|
|
|
"Script files" are command sequences that will be executed by
|
|
U-Boot's command interpreter; this feature is especially
|
|
useful when you configure U-Boot to use a real shell (hush)
|
|
as command interpreter.
|
|
|
|
Booting the Linux zImage:
|
|
-------------------------
|
|
|
|
On some platforms, it's possible to boot Linux zImage. This is done
|
|
using the "bootz" command. The syntax of "bootz" command is the same
|
|
as the syntax of "bootm" command.
|
|
|
|
Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
|
|
kernel with raw initrd images. The syntax is slightly different, the
|
|
address of the initrd must be augmented by it's size, in the following
|
|
format: "<initrd addres>:<initrd size>".
|
|
|
|
|
|
Standalone HOWTO:
|
|
=================
|
|
|
|
One of the features of U-Boot is that you can dynamically load and
|
|
run "standalone" applications, which can use some resources of
|
|
U-Boot like console I/O functions or interrupt services.
|
|
|
|
Two simple examples are included with the sources:
|
|
|
|
"Hello World" Demo:
|
|
-------------------
|
|
|
|
'examples/hello_world.c' contains a small "Hello World" Demo
|
|
application; it is automatically compiled when you build U-Boot.
|
|
It's configured to run at address 0x00040004, so you can play with it
|
|
like that:
|
|
|
|
=> loads
|
|
## Ready for S-Record download ...
|
|
~>examples/hello_world.srec
|
|
1 2 3 4 5 6 7 8 9 10 11 ...
|
|
[file transfer complete]
|
|
[connected]
|
|
## Start Addr = 0x00040004
|
|
|
|
=> go 40004 Hello World! This is a test.
|
|
## Starting application at 0x00040004 ...
|
|
Hello World
|
|
argc = 7
|
|
argv[0] = "40004"
|
|
argv[1] = "Hello"
|
|
argv[2] = "World!"
|
|
argv[3] = "This"
|
|
argv[4] = "is"
|
|
argv[5] = "a"
|
|
argv[6] = "test."
|
|
argv[7] = "<NULL>"
|
|
Hit any key to exit ...
|
|
|
|
## Application terminated, rc = 0x0
|
|
|
|
Another example, which demonstrates how to register a CPM interrupt
|
|
handler with the U-Boot code, can be found in 'examples/timer.c'.
|
|
Here, a CPM timer is set up to generate an interrupt every second.
|
|
The interrupt service routine is trivial, just printing a '.'
|
|
character, but this is just a demo program. The application can be
|
|
controlled by the following keys:
|
|
|
|
? - print current values og the CPM Timer registers
|
|
b - enable interrupts and start timer
|
|
e - stop timer and disable interrupts
|
|
q - quit application
|
|
|
|
=> loads
|
|
## Ready for S-Record download ...
|
|
~>examples/timer.srec
|
|
1 2 3 4 5 6 7 8 9 10 11 ...
|
|
[file transfer complete]
|
|
[connected]
|
|
## Start Addr = 0x00040004
|
|
|
|
=> go 40004
|
|
## Starting application at 0x00040004 ...
|
|
TIMERS=0xfff00980
|
|
Using timer 1
|
|
tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
|
|
|
|
Hit 'b':
|
|
[q, b, e, ?] Set interval 1000000 us
|
|
Enabling timer
|
|
Hit '?':
|
|
[q, b, e, ?] ........
|
|
tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
|
|
Hit '?':
|
|
[q, b, e, ?] .
|
|
tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
|
|
Hit '?':
|
|
[q, b, e, ?] .
|
|
tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
|
|
Hit '?':
|
|
[q, b, e, ?] .
|
|
tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
|
|
Hit 'e':
|
|
[q, b, e, ?] ...Stopping timer
|
|
Hit 'q':
|
|
[q, b, e, ?] ## Application terminated, rc = 0x0
|
|
|
|
|
|
Implementation Internals:
|
|
=========================
|
|
|
|
The following is not intended to be a complete description of every
|
|
implementation detail. However, it should help to understand the
|
|
inner workings of U-Boot and make it easier to port it to custom
|
|
hardware.
|
|
|
|
|
|
Initial Stack, Global Data:
|
|
---------------------------
|
|
|
|
The implementation of U-Boot is complicated by the fact that U-Boot
|
|
starts running out of ROM (flash memory), usually without access to
|
|
system RAM (because the memory controller is not initialized yet).
|
|
This means that we don't have writable Data or BSS segments, and BSS
|
|
is not initialized as zero. To be able to get a C environment working
|
|
at all, we have to allocate at least a minimal stack. Implementation
|
|
options for this are defined and restricted by the CPU used: Some CPU
|
|
models provide on-chip memory (like the IMMR area on MPC8xx and
|
|
MPC826x processors), on others (parts of) the data cache can be
|
|
locked as (mis-) used as memory, etc.
|
|
|
|
Chris Hallinan posted a good summary of these issues to the
|
|
U-Boot mailing list:
|
|
|
|
Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
|
|
From: "Chris Hallinan" <clh@net1plus.com>
|
|
Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
|
|
...
|
|
|
|
Correct me if I'm wrong, folks, but the way I understand it
|
|
is this: Using DCACHE as initial RAM for Stack, etc, does not
|
|
require any physical RAM backing up the cache. The cleverness
|
|
is that the cache is being used as a temporary supply of
|
|
necessary storage before the SDRAM controller is setup. It's
|
|
beyond the scope of this list to explain the details, but you
|
|
can see how this works by studying the cache architecture and
|
|
operation in the architecture and processor-specific manuals.
|
|
|
|
OCM is On Chip Memory, which I believe the 405GP has 4K. It
|
|
is another option for the system designer to use as an
|
|
initial stack/RAM area prior to SDRAM being available. Either
|
|
option should work for you. Using CS 4 should be fine if your
|
|
board designers haven't used it for something that would
|
|
cause you grief during the initial boot! It is frequently not
|
|
used.
|
|
|
|
CFG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
|
|
with your processor/board/system design. The default value
|
|
you will find in any recent u-boot distribution in
|
|
walnut.h should work for you. I'd set it to a value larger
|
|
than your SDRAM module. If you have a 64MB SDRAM module, set
|
|
it above 400_0000. Just make sure your board has no resources
|
|
that are supposed to respond to that address! That code in
|
|
start.S has been around a while and should work as is when
|
|
you get the config right.
|
|
|
|
-Chris Hallinan
|
|
DS4.COM, Inc.
|
|
|
|
It is essential to remember this, since it has some impact on the C
|
|
code for the initialization procedures:
|
|
|
|
* Initialized global data (data segment) is read-only. Do not attempt
|
|
to write it.
|
|
|
|
* Do not use any uninitialized global data (or implicitly initialized
|
|
as zero data - BSS segment) at all - this is undefined, initiali-
|
|
zation is performed later (when relocating to RAM).
|
|
|
|
* Stack space is very limited. Avoid big data buffers or things like
|
|
that.
|
|
|
|
Having only the stack as writable memory limits means we cannot use
|
|
normal global data to share information between the code. But it
|
|
turned out that the implementation of U-Boot can be greatly
|
|
simplified by making a global data structure (gd_t) available to all
|
|
functions. We could pass a pointer to this data as argument to _all_
|
|
functions, but this would bloat the code. Instead we use a feature of
|
|
the GCC compiler (Global Register Variables) to share the data: we
|
|
place a pointer (gd) to the global data into a register which we
|
|
reserve for this purpose.
|
|
|
|
When choosing a register for such a purpose we are restricted by the
|
|
relevant (E)ABI specifications for the current architecture, and by
|
|
GCC's implementation.
|
|
|
|
For PowerPC, the following registers have specific use:
|
|
R1: stack pointer
|
|
R2: reserved for system use
|
|
R3-R4: parameter passing and return values
|
|
R5-R10: parameter passing
|
|
R13: small data area pointer
|
|
R30: GOT pointer
|
|
R31: frame pointer
|
|
|
|
(U-Boot also uses R12 as internal GOT pointer. r12
|
|
is a volatile register so r12 needs to be reset when
|
|
going back and forth between asm and C)
|
|
|
|
==> U-Boot will use R2 to hold a pointer to the global data
|
|
|
|
Note: on PPC, we could use a static initializer (since the
|
|
address of the global data structure is known at compile time),
|
|
but it turned out that reserving a register results in somewhat
|
|
smaller code - although the code savings are not that big (on
|
|
average for all boards 752 bytes for the whole U-Boot image,
|
|
624 text + 127 data).
|
|
|
|
On ARM, the following registers are used:
|
|
|
|
R0: function argument word/integer result
|
|
R1-R3: function argument word
|
|
R9: platform specific
|
|
R10: stack limit (used only if stack checking is enabled)
|
|
R11: argument (frame) pointer
|
|
R12: temporary workspace
|
|
R13: stack pointer
|
|
R14: link register
|
|
R15: program counter
|
|
|
|
==> U-Boot will use R9 to hold a pointer to the global data
|
|
|
|
Note: on ARM, only R_ARM_RELATIVE relocations are supported.
|
|
|
|
On Nios II, the ABI is documented here:
|
|
https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
|
|
|
|
==> U-Boot will use gp to hold a pointer to the global data
|
|
|
|
Note: on Nios II, we give "-G0" option to gcc and don't use gp
|
|
to access small data sections, so gp is free.
|
|
|
|
On RISC-V, the following registers are used:
|
|
|
|
x0: hard-wired zero (zero)
|
|
x1: return address (ra)
|
|
x2: stack pointer (sp)
|
|
x3: global pointer (gp)
|
|
x4: thread pointer (tp)
|
|
x5: link register (t0)
|
|
x8: frame pointer (fp)
|
|
x10-x11: arguments/return values (a0-1)
|
|
x12-x17: arguments (a2-7)
|
|
x28-31: temporaries (t3-6)
|
|
pc: program counter (pc)
|
|
|
|
==> U-Boot will use gp to hold a pointer to the global data
|
|
|
|
System Initialization:
|
|
----------------------
|
|
|
|
In the reset configuration, U-Boot starts at the reset entry point
|
|
(on most PowerPC systems at address 0x00000100). Because of the reset
|
|
configuration for CS0# this is a mirror of the on board Flash memory.
|
|
To be able to re-map memory U-Boot then jumps to its link address.
|
|
To be able to implement the initialization code in C, a (small!)
|
|
initial stack is set up in the internal Dual Ported RAM (in case CPUs
|
|
which provide such a feature like), or in a locked part of the data
|
|
cache. After that, U-Boot initializes the CPU core, the caches and
|
|
the SIU.
|
|
|
|
Next, all (potentially) available memory banks are mapped using a
|
|
preliminary mapping. For example, we put them on 512 MB boundaries
|
|
(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
|
|
on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
|
|
programmed for SDRAM access. Using the temporary configuration, a
|
|
simple memory test is run that determines the size of the SDRAM
|
|
banks.
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|
|
|
When there is more than one SDRAM bank, and the banks are of
|
|
different size, the largest is mapped first. For equal size, the first
|
|
bank (CS2#) is mapped first. The first mapping is always for address
|
|
0x00000000, with any additional banks following immediately to create
|
|
contiguous memory starting from 0.
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|
|
|
Then, the monitor installs itself at the upper end of the SDRAM area
|
|
and allocates memory for use by malloc() and for the global Board
|
|
Info data; also, the exception vector code is copied to the low RAM
|
|
pages, and the final stack is set up.
|
|
|
|
Only after this relocation will you have a "normal" C environment;
|
|
until that you are restricted in several ways, mostly because you are
|
|
running from ROM, and because the code will have to be relocated to a
|
|
new address in RAM.
|
|
|
|
|
|
Contributing
|
|
============
|
|
|
|
The U-Boot projects depends on contributions from the user community.
|
|
If you want to participate, please, have a look at the 'General'
|
|
section of https://docs.u-boot.org/en/latest/develop/index.html
|
|
where we describe coding standards and the patch submission process.
|