#

# (C) Copyright 2000 - 2013

# Wolfgang Denk, DENX Software Engineering, wd@denx.de.

#

# SPDX-License-Identifier: GPL-2.0+

#

Summary:

========

This directory contains the source code for U-Boot, a boot loader for

Embedded boards based on PowerPC, ARM, MIPS and several other

processors, which can be installed in a boot ROM and used to

initialize and test the hardware or to download and run application

code.

The development of U-Boot is closely related to Linux: some parts of

the source code originate in the Linux source tree, we have some

header files in common, and special provision has been made to

support booting of Linux images.

Some attention has been paid to make this software easily

configurable and extendable. For instance, all monitor commands are

implemented with the same call interface, so that it's very easy to

add new commands. Also, instead of permanently adding rarely used

code (for instance hardware test utilities) to the monitor, you can

load and run it dynamically.

Status:

=======

In general, all boards for which a configuration option exists in the

Makefile have been tested to some extent and can be considered

"working". In fact, many of them are used in production systems.

In case of problems see the CHANGELOG file to find out who contributed

the specific port. In addition, there are various MAINTAINERS files

scattered throughout the U-Boot source identifying the people or

companies responsible for various boards and subsystems.

Note: As of August, 2010, there is no longer a CHANGELOG file in the

actual U-Boot source tree; however, it can be created dynamically

from the Git log using:

make CHANGELOG

Where to get help:

==================

In case you have questions about, problems with or contributions for

U-Boot, you should send a message to the U-Boot mailing list at

<u-boot@lists.denx.de>. There is also an archive of previous traffic

on the mailing list - please search the archive before asking FAQ's.

Please see http://lists.denx.de/pipermail/u-boot and

http://dir.gmane.org/gmane.comp.boot-loaders.u-boot

Where to get source code:

=========================

The U-Boot source code is maintained in the Git repository at

git://www.denx.de/git/u-boot.git ; you can browse it online at

http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary

The "snapshot" links on this page allow you to download tarballs of

any version you might be interested in. Official releases are also

available for FTP download from the ftp://ftp.denx.de/pub/u-boot/

directory.

Pre-built (and tested) images are available from

ftp://ftp.denx.de/pub/u-boot/images/

Where we come from:

===================

- start from 8xxrom sources

- create PPCBoot project (http://sourceforge.net/projects/ppcboot)

- clean up code

- make it easier to add custom boards

- make it possible to add other [PowerPC] CPUs

- extend functions, especially:

* Provide extended interface to Linux boot loader

* S-Record download

* network boot

* PCMCIA / CompactFlash / ATA disk / SCSI ... boot

- create ARMBoot project (http://sourceforge.net/projects/armboot)

- add other CPU families (starting with ARM)

- create U-Boot project (http://sourceforge.net/projects/u-boot)

- current project page: see http://www.denx.de/wiki/U-Boot

Names and Spelling:

===================

The "official" name of this project is "Das U-Boot". The spelling

"U-Boot" shall be used in all written text (documentation, comments

in source files etc.). Example:

This is the README file for the U-Boot project.

File names etc. shall be based on the string "u-boot". Examples:

include/asm-ppc/u-boot.h

#include <asm/u-boot.h>

Variable names, preprocessor constants etc. shall be either based on

the string "u_boot" or on "U_BOOT". Example:

U_BOOT_VERSION u_boot_logo

IH_OS_U_BOOT u_boot_hush_start

Versioning:

===========

Starting with the release in October 2008, the names of the releases

were changed from numerical release numbers without deeper meaning

into a time stamp based numbering. Regular releases are identified by

names consisting of the calendar year and month of the release date.

Additional fields (if present) indicate release candidates or bug fix

releases in "stable" maintenance trees.

Examples:

U-Boot v2009.11 - Release November 2009

U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree

U-Boot v2010.09-rc1 - Release candiate 1 for September 2010 release

Directory Hierarchy:

====================

/arch Architecture specific files

/arc Files generic to ARC architecture

/arm Files generic to ARM architecture

/avr32 Files generic to AVR32 architecture

/blackfin Files generic to Analog Devices Blackfin architecture

/m68k Files generic to m68k architecture

/microblaze Files generic to microblaze architecture

/mips Files generic to MIPS architecture

/nds32 Files generic to NDS32 architecture

/nios2 Files generic to Altera NIOS2 architecture

/openrisc Files generic to OpenRISC architecture

/powerpc Files generic to PowerPC architecture

/sandbox Files generic to HW-independent "sandbox"

/sh Files generic to SH architecture

/sparc Files generic to SPARC architecture

/x86 Files generic to x86 architecture

/api Machine/arch independent API for external apps

/board Board dependent files

/cmd U-Boot commands functions

/common Misc architecture independent functions

/configs Board default configuration files

/disk Code for disk drive partition handling

/doc Documentation (don't expect too much)

/drivers Commonly used device drivers

/dts Contains Makefile for building internal U-Boot fdt.

/examples Example code for standalone applications, etc.

/fs Filesystem code (cramfs, ext2, jffs2, etc.)

/include Header Files

/lib Library routines generic to all architectures

/Licenses Various license files

/net Networking code

/post Power On Self Test

/scripts Various build scripts and Makefiles

/test Various unit test files

/tools Tools to build S-Record or U-Boot images, etc.

Software Configuration:

=======================

Configuration is usually done using C preprocessor defines; the

rationale behind that is to avoid dead code whenever possible.

There are two classes of configuration variables:

* Configuration _OPTIONS_:

These are selectable by the user and have names beginning with

"CONFIG_".

* Configuration _SETTINGS_:

These depend on the hardware etc. and should not be meddled with if

you don't know what you're doing; they have names beginning with

"CONFIG_SYS_".

Previously, all configuration was done by hand, which involved creating

symbolic links and editing configuration files manually. More recently,

U-Boot has added the Kbuild infrastructure used by the Linux kernel,

allowing you to use the "make menuconfig" command to configure your

build.

Selection of Processor Architecture and Board Type:

---------------------------------------------------

For all supported boards there are ready-to-use default

configurations available; just type "make <board_name>_defconfig".

Example: For a TQM823L module type:

cd u-boot

make TQM823L_defconfig

Note: If you're looking for the default configuration file for a board

you're sure used to be there but is now missing, check the file

doc/README.scrapyard for a list of no longer supported boards.

Sandbox Environment:

--------------------

U-Boot can be built natively to run on a Linux host using the 'sandbox'

board. This allows feature development which is not board- or architecture-

specific to be undertaken on a native platform. The sandbox is also used to

run some of U-Boot's tests.

See board/sandbox/README.sandbox for more details.

Board Initialisation Flow:

--------------------------

This is the intended start-up flow for boards. This should apply for both

SPL and U-Boot proper (i.e. they both follow the same rules).

Note: "SPL" stands for "Secondary Program Loader," which is explained in

more detail later in this file.

At present, SPL mostly uses a separate code path, but the function names

and roles of each function are the same. Some boards or architectures

may not conform to this. At least most ARM boards which use

CONFIG_SPL_FRAMEWORK conform to this.

Execution typically starts with an architecture-specific (and possibly

CPU-specific) start.S file, such as:

- arch/arm/cpu/armv7/start.S

- arch/powerpc/cpu/mpc83xx/start.S

- arch/mips/cpu/start.S

and so on. From there, three functions are called; the purpose and

limitations of each of these functions are described below.

lowlevel_init():

- purpose: essential init to permit execution to reach board_init_f()

- no global_data or BSS

- there is no stack (ARMv7 may have one but it will soon be removed)

- must not set up SDRAM or use console

- must only do the bare minimum to allow execution to continue to

board_init_f()

- this is almost never needed

- return normally from this function

board_init_f():

- purpose: set up the machine ready for running board_init_r():

i.e. SDRAM and serial UART

- global_data is available

- stack is in SRAM

- BSS is not available, so you cannot use global/static variables,

only stack variables and global_data

Non-SPL-specific notes:

- dram_init() is called to set up DRAM. If already done in SPL this

can do nothing

SPL-specific notes:

- you can override the entire board_init_f() function with your own

version as needed.

- preloader_console_init() can be called here in extremis

- should set up SDRAM, and anything needed to make the UART work

- these is no need to clear BSS, it will be done by crt0.S

- must return normally from this function (don't call board_init_r()

directly)

Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at

this point the stack and global_data are relocated to below

CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of

memory.

board_init_r():

- purpose: main execution, common code

- global_data is available

- SDRAM is available

- BSS is available, all static/global variables can be used

- execution eventually continues to main_loop()

Non-SPL-specific notes:

- U-Boot is relocated to the top of memory and is now running from

there.

SPL-specific notes:

- stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and

CONFIG_SPL_STACK_R_ADDR points into SDRAM

- preloader_console_init() can be called here - typically this is

done by defining CONFIG_SPL_BOARD_INIT and then supplying a

spl_board_init() function containing this call

- loads U-Boot or (in falcon mode) Linux

Configuration Options:

----------------------

Configuration depends on the combination of board and CPU type; all

such information is kept in a configuration file

"include/configs/<board_name>.h".

Example: For a TQM823L module, all configuration settings are in

"include/configs/TQM823L.h".

Many of the options are named exactly as the corresponding Linux

kernel configuration options. The intention is to make it easier to

build a config tool - later.

The following options need to be configured:

- CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.

- Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.

- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)

Define exactly one, e.g. CONFIG_ATSTK1002

- CPU Module Type: (if CONFIG_COGENT is defined)

Define exactly one of

CONFIG_CMA286_60_OLD

--- FIXME --- not tested yet:

CONFIG_CMA286_60, CONFIG_CMA286_21, CONFIG_CMA286_60P,

CONFIG_CMA287_23, CONFIG_CMA287_50

- Motherboard Type: (if CONFIG_COGENT is defined)

Define exactly one of

CONFIG_CMA101, CONFIG_CMA102

- Motherboard I/O Modules: (if CONFIG_COGENT is defined)

Define one or more of

CONFIG_CMA302

- Motherboard Options: (if CONFIG_CMA101 or CONFIG_CMA102 are defined)

Define one or more of

CONFIG_LCD_HEARTBEAT - update a character position on

the LCD display every second with

a "rotator" |\-/|\-/

- Marvell Family Member

CONFIG_SYS_MVFS - define it if you want to enable

multiple fs option at one time

for marvell soc family

- 8xx CPU Options: (if using an MPC8xx CPU)

CONFIG_8xx_GCLK_FREQ - deprecated: CPU clock if

get_gclk_freq() cannot work

e.g. if there is no 32KHz

reference PIT/RTC clock

CONFIG_8xx_OSCLK - PLL input clock (either EXTCLK

or XTAL/EXTAL)

- 859/866/885 CPU options: (if using a MPC859 or MPC866 or MPC885 CPU):

CONFIG_SYS_8xx_CPUCLK_MIN

CONFIG_SYS_8xx_CPUCLK_MAX

CONFIG_8xx_CPUCLK_DEFAULT

See doc/README.MPC866

CONFIG_SYS_MEASURE_CPUCLK

Define this to measure the actual CPU clock instead

of relying on the correctness of the configured

values. Mostly useful for board bringup to make sure

the PLL is locked at the intended frequency. Note

that this requires a (stable) reference clock (32 kHz

RTC clock or CONFIG_SYS_8XX_XIN)

CONFIG_SYS_DELAYED_ICACHE

Define this option if you want to enable the

ICache only when Code runs from RAM.

- 85xx CPU Options:

CONFIG_SYS_PPC64

Specifies that the core is a 64-bit PowerPC implementation (implements

the "64" category of the Power ISA). This is necessary for ePAPR

compliance, among other possible reasons.

CONFIG_SYS_FSL_TBCLK_DIV

Defines the core time base clock divider ratio compared to the

system clock. On most PQ3 devices this is 8, on newer QorIQ

devices it can be 16 or 32. The ratio varies from SoC to Soc.

CONFIG_SYS_FSL_PCIE_COMPAT

Defines the string to utilize when trying to match PCIe device

tree nodes for the given platform.

CONFIG_SYS_PPC_E500_DEBUG_TLB

Enables a temporary TLB entry to be used during boot to work

around limitations in e500v1 and e500v2 external debugger

support. This reduces the portions of the boot code where

breakpoints and single stepping do not work. The value of this

symbol should be set to the TLB1 entry to be used for this

purpose.

CONFIG_SYS_FSL_ERRATUM_A004510

Enables a workaround for erratum A004510. If set,

then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and

CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.

CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV

CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)

Defines one or two SoC revisions (low 8 bits of SVR)

for which the A004510 workaround should be applied.

The rest of SVR is either not relevant to the decision

of whether the erratum is present (e.g. p2040 versus

p2041) or is implied by the build target, which controls

whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.

See Freescale App Note 4493 for more information about

this erratum.

CONFIG_A003399_NOR_WORKAROUND

Enables a workaround for IFC erratum A003399. It is only

required during NOR boot.

CONFIG_A008044_WORKAROUND

Enables a workaround for T1040/T1042 erratum A008044. It is only

required during NAND boot and valid for Rev 1.0 SoC revision

CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY

This is the value to write into CCSR offset 0x18600

according to the A004510 workaround.

CONFIG_SYS_FSL_DSP_DDR_ADDR

This value denotes start offset of DDR memory which is

connected exclusively to the DSP cores.

CONFIG_SYS_FSL_DSP_M2_RAM_ADDR

This value denotes start offset of M2 memory

which is directly connected to the DSP core.

CONFIG_SYS_FSL_DSP_M3_RAM_ADDR

This value denotes start offset of M3 memory which is directly

connected to the DSP core.

CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT

This value denotes start offset of DSP CCSR space.

CONFIG_SYS_FSL_SINGLE_SOURCE_CLK

Single Source Clock is clocking mode present in some of FSL SoC's.

In this mode, a single differential clock is used to supply

clocks to the sysclock, ddrclock and usbclock.

CONFIG_SYS_CPC_REINIT_F

This CONFIG is defined when the CPC is configured as SRAM at the

time of U-Boot entry and is required to be re-initialized.

CONFIG_DEEP_SLEEP

Indicates this SoC supports deep sleep feature. If deep sleep is

supported, core will start to execute uboot when wakes up.

- Generic CPU options:

CONFIG_SYS_GENERIC_GLOBAL_DATA

Defines global data is initialized in generic board board_init_f().

If this macro is defined, global data is created and cleared in

generic board board_init_f(). Without this macro, architecture/board

should initialize global data before calling board_init_f().

CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN

Defines the endianess of the CPU. Implementation of those

values is arch specific.

CONFIG_SYS_FSL_DDR

Freescale DDR driver in use. This type of DDR controller is

found in mpc83xx, mpc85xx, mpc86xx as well as some ARM core

SoCs.

CONFIG_SYS_FSL_DDR_ADDR

Freescale DDR memory-mapped register base.

CONFIG_SYS_FSL_DDR_EMU

Specify emulator support for DDR. Some DDR features such as

deskew training are not available.

CONFIG_SYS_FSL_DDRC_GEN1

Freescale DDR1 controller.

CONFIG_SYS_FSL_DDRC_GEN2

Freescale DDR2 controller.

CONFIG_SYS_FSL_DDRC_GEN3

Freescale DDR3 controller.

CONFIG_SYS_FSL_DDRC_GEN4

Freescale DDR4 controller.

CONFIG_SYS_FSL_DDRC_ARM_GEN3

Freescale DDR3 controller for ARM-based SoCs.

CONFIG_SYS_FSL_DDR1

Board config to use DDR1. It can be enabled for SoCs with

Freescale DDR1 or DDR2 controllers, depending on the board

implemetation.

CONFIG_SYS_FSL_DDR2

Board config to use DDR2. It can be enabled for SoCs with

Freescale DDR2 or DDR3 controllers, depending on the board

implementation.

CONFIG_SYS_FSL_DDR3

Board config to use DDR3. It can be enabled for SoCs with

Freescale DDR3 or DDR3L controllers.

CONFIG_SYS_FSL_DDR3L

Board config to use DDR3L. It can be enabled for SoCs with

DDR3L controllers.

CONFIG_SYS_FSL_DDR4

Board config to use DDR4. It can be enabled for SoCs with

DDR4 controllers.

CONFIG_SYS_FSL_IFC_BE

Defines the IFC controller register space as Big Endian

CONFIG_SYS_FSL_IFC_LE

Defines the IFC controller register space as Little Endian

CONFIG_SYS_FSL_PBL_PBI

It enables addition of RCW (Power on reset configuration) in built image.

Please refer doc/README.pblimage for more details

CONFIG_SYS_FSL_PBL_RCW

It adds PBI(pre-boot instructions) commands in u-boot build image.

PBI commands can be used to configure SoC before it starts the execution.

Please refer doc/README.pblimage for more details

CONFIG_SPL_FSL_PBL

It adds a target to create boot binary having SPL binary in PBI format

concatenated with u-boot binary.

CONFIG_SYS_FSL_DDR_BE

Defines the DDR controller register space as Big Endian

CONFIG_SYS_FSL_DDR_LE

Defines the DDR controller register space as Little Endian

CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY

Physical address from the view of DDR controllers. It is the

same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But

it could be different for ARM SoCs.

CONFIG_SYS_FSL_DDR_INTLV_256B

DDR controller interleaving on 256-byte. This is a special

interleaving mode, handled by Dickens for Freescale layerscape

SoCs with ARM core.

CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS

Number of controllers used as main memory.

CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS

Number of controllers used for other than main memory.

CONFIG_SYS_FSL_HAS_DP_DDR

Defines the SoC has DP-DDR used for DPAA.

CONFIG_SYS_FSL_SEC_BE

Defines the SEC controller register space as Big Endian

CONFIG_SYS_FSL_SEC_LE

Defines the SEC controller register space as Little Endian

- Intel Monahans options:

CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO

Defines the Monahans run mode to oscillator

ratio. Valid values are 8, 16, 24, 31. The core

frequency is this value multiplied by 13 MHz.

CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO

Defines the Monahans turbo mode to oscillator

ratio. Valid values are 1 (default if undefined) and

2. The core frequency as calculated above is multiplied

by this value.

- MIPS CPU options:

CONFIG_SYS_INIT_SP_OFFSET

Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack

pointer. This is needed for the temporary stack before

relocation.

CONFIG_SYS_MIPS_CACHE_MODE

Cache operation mode for the MIPS CPU.

See also arch/mips/include/asm/mipsregs.h.

Possible values are:

CONF_CM_CACHABLE_NO_WA

CONF_CM_CACHABLE_WA

CONF_CM_UNCACHED

CONF_CM_CACHABLE_NONCOHERENT

CONF_CM_CACHABLE_CE

CONF_CM_CACHABLE_COW

CONF_CM_CACHABLE_CUW

CONF_CM_CACHABLE_ACCELERATED

CONFIG_SYS_XWAY_EBU_BOOTCFG

Special option for Lantiq XWAY SoCs for booting from NOR flash.

See also arch/mips/cpu/mips32/start.S.

CONFIG_XWAY_SWAP_BYTES

Enable compilation of tools/xway-swap-bytes needed for Lantiq

XWAY SoCs for booting from NOR flash. The U-Boot image needs to

be swapped if a flash programmer is used.

- ARM options:

CONFIG_SYS_EXCEPTION_VECTORS_HIGH

Select high exception vectors of the ARM core, e.g., do not

clear the V bit of the c1 register of CP15.

CONFIG_SYS_THUMB_BUILD

Use this flag to build U-Boot using the Thumb instruction

set for ARM architectures. Thumb instruction set provides

better code density. For ARM architectures that support

Thumb2 this flag will result in Thumb2 code generated by

GCC.

CONFIG_ARM_ERRATA_716044

CONFIG_ARM_ERRATA_742230

CONFIG_ARM_ERRATA_743622

CONFIG_ARM_ERRATA_751472

CONFIG_ARM_ERRATA_761320

CONFIG_ARM_ERRATA_773022

CONFIG_ARM_ERRATA_774769

CONFIG_ARM_ERRATA_794072

If set, the workarounds for these ARM errata are applied early

during U-Boot startup. Note that these options force the

workarounds to be applied; no CPU-type/version detection

exists, unlike the similar options in the Linux kernel. Do not

set these options unless they apply!

COUNTER_FREQUENCY

Generic timer clock source frequency.

COUNTER_FREQUENCY_REAL

Generic timer clock source frequency if the real clock is

different from COUNTER_FREQUENCY, and can only be determined

at run time.

NOTE: The following can be machine specific errata. These

do have ability to provide rudimentary version and machine

specific checks, but expect no product checks.

CONFIG_ARM_ERRATA_430973

CONFIG_ARM_ERRATA_454179

CONFIG_ARM_ERRATA_621766

CONFIG_ARM_ERRATA_798870

CONFIG_ARM_ERRATA_801819

- Tegra SoC options:

CONFIG_TEGRA_SUPPORT_NON_SECURE

Support executing U-Boot in non-secure (NS) mode. Certain

impossible actions will be skipped if the CPU is in NS mode,

such as ARM architectural timer initialization.

- Linux Kernel Interface:

CONFIG_CLOCKS_IN_MHZ

U-Boot stores all clock information in Hz

internally. For binary compatibility with older Linux

kernels (which expect the clocks passed in the

bd_info data to be in MHz) the environment variable

"clocks_in_mhz" can be defined so that U-Boot

converts clock data to MHZ before passing it to the

Linux kernel.

When CONFIG_CLOCKS_IN_MHZ is defined, a definition of

"clocks_in_mhz=1" is automatically included in the

default environment.

CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]

When transferring memsize parameter to Linux, some versions

expect it to be in bytes, others in MB.

Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.

CONFIG_OF_LIBFDT

New kernel versions are expecting firmware settings to be

passed using flattened device trees (based on open firmware

concepts).

CONFIG_OF_LIBFDT

* New libfdt-based support

* Adds the "fdt" command

* The bootm command automatically updates the fdt

OF_CPU - The proper name of the cpus node (only required for

MPC512X and MPC5xxx based boards).

OF_SOC - The proper name of the soc node (only required for

MPC512X and MPC5xxx based boards).

OF_TBCLK - The timebase frequency.

OF_STDOUT_PATH - The path to the console device

boards with QUICC Engines require OF_QE to set UCC MAC

addresses

CONFIG_OF_BOARD_SETUP

Board code has addition modification that it wants to make

to the flat device tree before handing it off to the kernel

CONFIG_OF_SYSTEM_SETUP

Other code has addition modification that it wants to make

to the flat device tree before handing it off to the kernel.

This causes ft_system_setup() to be called before booting

the kernel.

CONFIG_OF_BOOT_CPU

This define fills in the correct boot CPU in the boot

param header, the default value is zero if undefined.

CONFIG_OF_IDE_FIXUP

U-Boot can detect if an IDE device is present or not.

If not, and this new config option is activated, U-Boot

removes the ATA node from the DTS before booting Linux,

so the Linux IDE driver does not probe the device and

crash. This is needed for buggy hardware (uc101) where

no pull down resistor is connected to the signal IDE5V_DD7.

CONFIG_MACH_TYPE [relevant for ARM only][mandatory]

This setting is mandatory for all boards that have only one

machine type and must be used to specify the machine type

number as it appears in the ARM machine registry

(see http://www.arm.linux.org.uk/developer/machines/).

Only boards that have multiple machine types supported

in a single configuration file and the machine type is

runtime discoverable, do not have to use this setting.

- vxWorks boot parameters:

bootvx constructs a valid bootline using the following

environments variables: bootdev, bootfile, ipaddr, netmask,

serverip, gatewayip, hostname, othbootargs.

It loads the vxWorks image pointed bootfile.

Note: If a "bootargs" environment is defined, it will overwride

the defaults discussed just above.

- Cache Configuration:

CONFIG_SYS_ICACHE_OFF - Do not enable instruction cache in U-Boot

CONFIG_SYS_DCACHE_OFF - Do not enable data cache in U-Boot

CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot

- Cache Configuration for ARM:

CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache

controller

CONFIG_SYS_PL310_BASE - Physical base address of PL310

controller register space

- Serial Ports:

CONFIG_PL010_SERIAL

Define this if you want support for Amba PrimeCell PL010 UARTs.

CONFIG_PL011_SERIAL

Define this if you want support for Amba PrimeCell PL011 UARTs.

CONFIG_PL011_CLOCK

If you have Amba PrimeCell PL011 UARTs, set this variable to

the clock speed of the UARTs.

CONFIG_PL01x_PORTS

If you have Amba PrimeCell PL010 or PL011 UARTs on your board,

define this to a list of base addresses for each (supported)

port. See e.g. include/configs/versatile.h

CONFIG_SERIAL_HW_FLOW_CONTROL

Define this variable to enable hw flow control in serial driver.

Current user of this option is drivers/serial/nsl16550.c driver

- Console Interface:

Depending on board, define exactly one serial port

(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,

CONFIG_8xx_CONS_SCC1, ...), or switch off the serial

console by defining CONFIG_8xx_CONS_NONE

Note: if CONFIG_8xx_CONS_NONE is defined, the serial

port routines must be defined elsewhere

(i.e. serial_init(), serial_getc(), ...)

CONFIG_CFB_CONSOLE

Enables console device for a color framebuffer. Needs following

defines (cf. smiLynxEM, i8042)

VIDEO_FB_LITTLE_ENDIAN graphic memory organisation

(default big endian)

VIDEO_HW_RECTFILL graphic chip supports

rectangle fill

(cf. smiLynxEM)

VIDEO_HW_BITBLT graphic chip supports

bit-blit (cf. smiLynxEM)

VIDEO_VISIBLE_COLS visible pixel columns

(cols=pitch)

VIDEO_VISIBLE_ROWS visible pixel rows

VIDEO_PIXEL_SIZE bytes per pixel

VIDEO_DATA_FORMAT graphic data format

(0-5, cf. cfb_console.c)

VIDEO_FB_ADRS framebuffer address

VIDEO_KBD_INIT_FCT keyboard int fct

(i.e. rx51_kp_init())

VIDEO_TSTC_FCT test char fct

(i.e. rx51_kp_tstc)

VIDEO_GETC_FCT get char fct

(i.e. rx51_kp_getc)

CONFIG_VIDEO_LOGO display Linux logo in

upper left corner

CONFIG_VIDEO_BMP_LOGO use bmp_logo.h instead of

linux_logo.h for logo.

Requires CONFIG_VIDEO_LOGO

CONFIG_CONSOLE_EXTRA_INFO

additional board info beside

the logo

CONFIG_HIDE_LOGO_VERSION

do not display bootloader

version string

When CONFIG_CFB_CONSOLE_ANSI is defined, console will support

a limited number of ANSI escape sequences (cursor control,

erase functions and limited graphics rendition control).

When CONFIG_CFB_CONSOLE is defined, video console is

default i/o. Serial console can be forced with

environment 'console=serial'.

When CONFIG_SILENT_CONSOLE is defined, all console

messages (by U-Boot and Linux!) can be silenced with

the "silent" environment variable. See

doc/README.silent for more information.

CONFIG_SYS_CONSOLE_BG_COL: define the backgroundcolor, default

is 0x00.

CONFIG_SYS_CONSOLE_FG_COL: define the foregroundcolor, default

is 0xa0.

- Console Baudrate:

CONFIG_BAUDRATE - in bps

Select one of the baudrates listed in

CONFIG_SYS_BAUDRATE_TABLE, see below.

CONFIG_SYS_BRGCLK_PRESCALE, baudrate prescale

- Console Rx buffer length

With CONFIG_SYS_SMC_RXBUFLEN it is possible to define

the maximum receive buffer length for the SMC.

This option is actual only for 82xx and 8xx possible.

If using CONFIG_SYS_SMC_RXBUFLEN also CONFIG_SYS_MAXIDLE

must be defined, to setup the maximum idle timeout for

the SMC.

- Pre-Console Buffer:

Prior to the console being initialised (i.e. serial UART

initialised etc) all console output is silently discarded.

Defining CONFIG_PRE_CONSOLE_BUFFER will cause U-Boot to

buffer any console messages prior to the console being

initialised to a buffer of size CONFIG_PRE_CON_BUF_SZ

bytes located at CONFIG_PRE_CON_BUF_ADDR. The buffer is

a circular buffer, so if more than CONFIG_PRE_CON_BUF_SZ

bytes are output before the console is initialised, the

earlier bytes are discarded.

Note that when printing the buffer a copy is made on the

stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack.

'Sane' compilers will generate smaller code if

CONFIG_PRE_CON_BUF_SZ is a power of 2

- Autoboot Command:

CONFIG_BOOTCOMMAND

Only needed when CONFIG_BOOTDELAY is enabled;

define a command string that is automatically executed

when no character is read on the console interface

within "Boot Delay" after reset.

CONFIG_BOOTARGS

This can be used to pass arguments to the bootm

command. The value of CONFIG_BOOTARGS goes into the

environment value "bootargs".

CONFIG_RAMBOOT and CONFIG_NFSBOOT

The value of these goes into the environment as

"ramboot" and "nfsboot" respectively, and can be used

as a convenience, when switching between booting from

RAM and NFS.

- Bootcount:

CONFIG_BOOTCOUNT_LIMIT

Implements a mechanism for detecting a repeating reboot

cycle, see:

http://www.denx.de/wiki/view/DULG/UBootBootCountLimit

CONFIG_BOOTCOUNT_ENV

If no softreset save registers are found on the hardware

"bootcount" is stored in the environment. To prevent a

saveenv on all reboots, the environment variable

"upgrade_available" is used. If "upgrade_available" is

0, "bootcount" is always 0, if "upgrade_available" is

1 "bootcount" is incremented in the environment.

So the Userspace Applikation must set the "upgrade_available"

and "bootcount" variable to 0, if a boot was successfully.

- Pre-Boot Commands:

CONFIG_PREBOOT

When this option is #defined, the existence of the

environment variable "preboot" will be checked

immediately before starting the CONFIG_BOOTDELAY

countdown and/or running the auto-boot command resp.

entering interactive mode.

This feature is especially useful when "preboot" is

automatically generated or modified. For an example

see the LWMON board specific code: here "preboot" is

modified when the user holds down a certain

combination of keys on the (special) keyboard when

booting the systems

- Serial Download Echo Mode:

CONFIG_LOADS_ECHO

If defined to 1, all characters received during a

serial download (using the "loads" command) are

echoed back. This might be needed by some terminal

emulations (like "cu"), but may as well just take

time on others. This setting #define's the initial

value of the "loads_echo" environment variable.

- Kgdb Serial Baudrate: (if CONFIG_CMD_KGDB is defined)

CONFIG_KGDB_BAUDRATE

Select one of the baudrates listed in

CONFIG_SYS_BAUDRATE_TABLE, see below.

- Monitor Functions:

Monitor commands can be included or excluded

from the build by using the #include files

<config_cmd_all.h> and #undef'ing unwanted

commands, or adding #define's for wanted commands.

The default command configuration includes all commands

except those marked below with a "*".

CONFIG_CMD_AES AES 128 CBC encrypt/decrypt

CONFIG_CMD_ASKENV * ask for env variable

CONFIG_CMD_BDI bdinfo

CONFIG_CMD_BEDBUG * Include BedBug Debugger

CONFIG_CMD_BMP * BMP support

CONFIG_CMD_BSP * Board specific commands

CONFIG_CMD_BOOTD bootd

CONFIG_CMD_BOOTI * ARM64 Linux kernel Image support

CONFIG_CMD_CACHE * icache, dcache

CONFIG_CMD_CLK * clock command support

CONFIG_CMD_CONSOLE coninfo

CONFIG_CMD_CRC32 * crc32

CONFIG_CMD_DATE * support for RTC, date/time...

CONFIG_CMD_DHCP * DHCP support

CONFIG_CMD_DIAG * Diagnostics

CONFIG_CMD_DS4510 * ds4510 I2C gpio commands

CONFIG_CMD_DS4510_INFO * ds4510 I2C info command

CONFIG_CMD_DS4510_MEM * ds4510 I2C eeprom/sram commansd

CONFIG_CMD_DS4510_RST * ds4510 I2C rst command

CONFIG_CMD_DTT * Digital Therm and Thermostat

CONFIG_CMD_ECHO echo arguments

CONFIG_CMD_EDITENV edit env variable

CONFIG_CMD_EEPROM * EEPROM read/write support

CONFIG_CMD_EEPROM_LAYOUT* EEPROM layout aware commands

CONFIG_CMD_ELF * bootelf, bootvx

CONFIG_CMD_ENV_CALLBACK * display details about env callbacks

CONFIG_CMD_ENV_FLAGS * display details about env flags

CONFIG_CMD_ENV_EXISTS * check existence of env variable

CONFIG_CMD_EXPORTENV * export the environment

CONFIG_CMD_EXT2 * ext2 command support

CONFIG_CMD_EXT4 * ext4 command support