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uboot2011.09源代码ReadMe译文

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#
# (C) Copyright 2000 - 2011
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#查看建立这个工程的文件列表人
#
#这个程序是自由软件,你可以重新分配它或者修改它在GNU通用公共许可证以由自由软件基#金会发布;第二版或者任何之后的版本。
#程序分布在希望有用的没有任何保证甚至没有隐含保证。

#查看 GNU通用公共许可证对于更多的细节。

#应该收到一份GNU通用公共许可证随着这个程序;如果没有,写信给自由软件组织。59 #Temple Place, Suite 330, Boston, MA 02111-1307 USA。

摘要:

======

这个目录包含了U-Boot源码一个引导装载程序基于PowerPC嵌入式ARMMIPS和其他几个处理器它可以安装在启动ROM和使用初始化测试硬件下载并运行应用程序代码


U-Boot的发展与Linux是密切相关的。部分的源代码是在Linux源代码树里。我们有一些常用的头文件特别规定支持引导Linux镜像

一些关注使得这个软件更容易配置和可扩展。例如,所有的监控命令以相同的调用接口实现因此它很容易添加新的命令。同时取代永久增加很少使用代码(例如硬件测试程序)监测动态地可以加载和运行它


状态

=======

一般来说所有的中存在一个Makefile文件已经过测试,在一定程度上可以考虑“工作”。事实上他们中的许多人都用在生产系统遇到问题时请在CHANGELOG和CREDITS文件中查找谁贡献的特定端口。MAINTAINERS文件列出了板的维护人员


从哪里获得帮助

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

如果你有问题问题的贡献U-boot。你应该将消息发送到邮件<u-boot@lists.denx.de>还有以往交通档案邮件列表,在要求的常见问题解答。搜索归档

请看http://lists.denx.de/pipermail/u-boothttp://dir.gmane.org/gmane.comp.boot-loaders.u-boot

从哪里获得源代码:

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

U-Boot源代码保存在Git库

git://www.denx.de/git/u-boot.git;你可以在网上浏览http://www.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=summary。“快照”这个网页上的链接允许你下载的压缩包任何版本,你可能会感兴趣。官方发布,也可从ftp://ftp.denx.de/pub/u-boot/ FTP下载目录。

预建的(和测试)的图像可从ftp://ftp.denx.de/pub/u-boot/images/

我们从哪里来:

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

从8xxrom源启动

创建PPCBoot项目(http://sourceforge.net/projects/ppcboot)

-清理代码

-使它更容易添加自定义板

-可以添加其他] [ PowerPC处理器

扩展功能,尤其是:

*提供扩展接口,Linux引导装载程序

*文件下载

*网络启动

* pcmcia / CompactFlash / ATA磁盘/ SCSI…启动

创建项目(http://sourceforge.net/projects/armboot)armboot

添加其他CPU的家族(从arm开始)

创建U-Boot项目(http://sourceforge.net/projects/u-boot)

目前项目页面:看http://www.denx.de/wiki/u-boot


名称和拼写:

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

该项目的“官方”的名字是“DAS u-boot”。拼写

“U-Boot”应该被应用于所有的书面文本(文档,评论

在源文件等)。例:

这是u-boot工程的自述文件。

文件名等应该被基于字符串“u-boot”。例:

      #include/asm-ppc/u-boot.h

    #include <asm/u-boot.h>

变量名称,预处理器常量等应基于

字符串“u_boot”或“u_boot”。例:

U_BOOT_VERSIONu_boot_logo

IH_OS_U_BOOTu_boot_hush_start

版本控制:

===========

从十月2008开始发布,发布的名字改变数值的版本号没有更深的意义,在基于时间戳的编号。定期发布是确定的组成的发布日期的日历年和月的名字。额外的域(如果存在)表示的候选发布或bug修复发布在“稳定”维护树。

例:

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

目录层次

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

Directory Hierarchy:

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


/arch                特定结构的文件

  /arm 通用的arm体系文件

    /cpu CPU 特定文件

      /arm720t Files specific to ARM 720 CPUs

      /arm920t Files specific to ARM 920 CPUs

/at91 Files specific to Atmel AT91RM9200 CPU

/imx Files specific to Freescale MC9328 i.MX CPUs

/s3c24x0 Files specific to Samsung S3C24X0 CPUs

      /arm925t Files specific to ARM 925 CPUs

      /arm926ejs Files specific to ARM 926 CPUs

      /arm1136 Files specific to ARM 1136 CPUs

      /ixp Files specific to Intel XScale IXP CPUs

      /pxa Files specific to Intel XScale PXA CPUs

      /s3c44b0Files specific to Samsung S3C44B0 CPUs

      /sa1100Files specific to Intel StrongARM SA1100 CPUs

    /libArchitecture specific library files

  /avr32Files generic to AVR32 architecture

    /cpuCPU specific files

    /libArchitecture specific library files

  /blackfinFiles generic to Analog Devices Blackfin architecture

    /cpuCPU specific files

    /libArchitecture specific library files

  /x86Files generic to x86 architecture

    /cpuCPU specific files

    /libArchitecture specific library files

  /m68kFiles generic to m68k architecture

    /cpuCPU specific files

      /mcf52x2Files specific to Freescale ColdFire MCF52x2 CPUs

      /mcf5227xFiles specific to Freescale ColdFire MCF5227x CPUs

      /mcf532xFiles specific to Freescale ColdFire MCF5329 CPUs

      /mcf5445xFiles specific to Freescale ColdFire MCF5445x CPUs

      /mcf547x_8xFiles specific to Freescale ColdFire MCF547x_8x CPUs

    /libArchitecture specific library files

  /microblazeFiles generic to microblaze architecture

    /cpuCPU specific files

    /libArchitecture specific library files

  /mipsFiles generic to MIPS architecture

    /cpuCPU specific files

      /mips32Files specific to MIPS32 CPUs

    /libArchitecture specific library files

  /nios2Files generic to Altera NIOS2 architecture

    /cpuCPU specific files

    /libArchitecture specific library files

  /powerpcFiles generic to PowerPC architecture

    /cpuCPU specific files

      /74xx_7xxFiles specific to Freescale MPC74xx and 7xx CPUs

      /mpc5xxFiles specific to Freescale MPC5xx CPUs

      /mpc5xxxFiles specific to Freescale MPC5xxx CPUs

      /mpc8xxFiles specific to Freescale MPC8xx CPUs

      /mpc8220Files specific to Freescale MPC8220 CPUs

      /mpc824xFiles specific to Freescale MPC824x CPUs

      /mpc8260Files specific to Freescale MPC8260 CPUs

      /mpc85xxFiles specific to Freescale MPC85xx CPUs

      /ppc4xxFiles specific to AMCC PowerPC 4xx CPUs

    /libArchitecture specific library files

  /shFiles generic to SH architecture

    /cpuCPU specific files

      /sh2Files specific to sh2 CPUs

      /sh3Files specific to sh3 CPUs

      /sh4Files specific to sh4 CPUs

    /libArchitecture specific library files

  /sparcFiles generic to SPARC architecture

    /cpuCPU specific files

      /leon2Files specific to Gaisler LEON2 SPARC CPU

      /leon3Files specific to Gaisler LEON3 SPARC CPU

    /libArchitecture specific library files

/apiMachine/arch independent API for external apps

/boardBoard dependent files

/commonMisc architecture independent functions

/diskCode for disk drive partition handling

/docDocumentation (don‘t expect too much)

/driversCommonly used device drivers

/examplesExample code for standalone applications, etc.

/fsFilesystem code (cramfs, ext2, jffs2, etc.)

/includeHeader Files

/libFiles generic to all architectures

  /libfdtLibrary files to support flattened device trees

  /lzmaLibrary files to support LZMA decompression

  /lzoLibrary files to support LZO decompression

/netNetworking code

/postPower On Self Test

/rtcReal Time Clock drivers

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


软件配置:
=======================
配置通常是使用C预处理器定义的;原因是尽可能避免死代码。
有两种类型的配置变量:
* Configuration _OPTIONS_:
这些都是由用户选定的和的名字开始
  "CONFIG_".
* Configuration _SETTINGS_:
这取决于硬件等不应干预如果
你不知道你在做什么;他们的名字开始
  "CONFIG_SYS_".
后面我们会添加一个配置工具可能类似于甚至什么是用于Linux内核相同。现在,我们必须
手动完成配置,这意味着创建一些符号链接和编辑配置文件。我们使用TQM8xxL开发板作为一个例子。

选择处理器架构和开发板类型:

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

所有支持的板有准备使用的默认配置;

比如"make <board_name>_config"

例如:一个tqm823l模块类型:

cd u-boot

make TQM823L_config

对于确定的平台,你同样需要指定CPU类型;

例. "make cogent_mpc8xx_config"并配置有说服力的记录文件


配置选项:

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

配置取决于板、CPU类型组合;所有这些信息保存在配置文件

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

例如:一个tqm823l模块,所有配置设置在

"include/configs/TQM823L.h".

有许多选项准确命名为相应的Linux内核配置选项。目的是使它更容易建立一个配置工具后。


需要配置的选项如下:

- CPU Type:正确地定义一个, e.g. CONFIG_MPC85XX.

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


- CPU 子板Type: (if CONFIG_ATSTK1000 is defined)

正确地定义一个 , 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


- 主板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- 更新一个字符的位置上液晶显示器的每一秒“旋转”|\-/|\-/


- Board 风格: (if CONFIG_MPC8260ADS is defined)

CONFIG_ADSTYPE

Possible values are:

CONFIG_SYS_8260ADS- original MPC8260ADS

CONFIG_SYS_8266ADS- MPC8266ADS

CONFIG_SYS_PQ2FADS- PQ2FADS-ZU or PQ2FADS-VR

CONFIG_SYS_8272ADS- MPC8272ADS


- Marvell Family Member

CONFIG_SYS_MVFS- define it if you want to enable

  multiple fs option at one time

  for marvell soc family


- MPC824X Family Member (if CONFIG_MPC824X is defined)

Define exactly one of

CONFIG_MPC8240, CONFIG_MPC8245


- 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


定义此来衡量实际的CPU时钟而不是 依靠正确的配置 价值观。通常用于单板确保 锁相环锁定在预定的频率。注意 这需要一个(稳定)的参考时钟(32千赫 RTC时钟或config_sys_8xx_xin)(32 kHzRTC clock or CONFIG_SYS_8XX_XIN)


CONFIG_SYS_DELAYED_ICACHE

            定义这个选项,当代码在ram中运行的时候如果你想使能iCache.


- 85xx CPU Options:

CONFIG_SYS_FSL_TBCLK_DIV


定义核心时基时钟分频比的 系统时钟。在大多数PQ3设备这是8,在新的QorIQ 设备可以是16或32。从SOC SOC的变化率。


CONFIG_SYS_FSL_PCIE_COMPAT


当试图定义利用PCIE设备的字符串匹配 对于给定的平台树节点。


- Intel Monahans options:

CONFIG_SYS_MONAHANS_RUN_MODE_OSC_RATIO


定义了Monahans的运行模式振荡器 比。有效值是8,16,24,31。核心 频率是这个值乘以13兆赫。


CONFIG_SYS_MONAHANS_TURBO_RUN_MODE_RATIO


定义的模式振荡器的Monahans的涡轮增压器 比。有效的值(默认为1,如果未定义) 2。上面的核心是计算的频率倍增 通过这个值。


- 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.

相对于config_sys_sdram_base初始偏移

指针。这是需要临时栈之前

搬迁。


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.


- 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_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: bootfile, ipaddr, serverip, hostname.

It loads the vxWorks image pointed bootfile.


CONFIG_SYS_VXWORKS_BOOT_DEVICE - The vxworks device name

CONFIG_SYS_VXWORKS_MAC_PTR - Ethernet 6 byte MA -address

CONFIG_SYS_VXWORKS_SERVERNAME - Name of the server

CONFIG_SYS_VXWORKS_BOOT_ADDR - Address of boot parameters


CONFIG_SYS_VXWORKS_ADD_PARAMS


Add it at the end of the bootline. E.g "u=username pw=secret"


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_PL011_SERIAL_RLCR


Some vendor versions of PL011 serial ports (e.g. ST-Ericsson U8500)

have separate receive and transmit line control registers.  Set

this variable to initialize the extra register.


CONFIG_PL011_SERIAL_FLUSH_ON_INIT


On some platforms (e.g. U8500) U-Boot is loaded by a second stage

boot loader that has already initialized the UART.  Define this

variable to flush the UART at init time.



- 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, board/eltec/bab7xx)

VIDEO_FB_LITTLE_ENDIANgraphic memory organisation

(default big endian)

VIDEO_HW_RECTFILLgraphic chip supports

rectangle fill

(cf. smiLynxEM)

VIDEO_HW_BITBLTgraphic chip supports

bit-blit (cf. smiLynxEM)

VIDEO_VISIBLE_COLSvisible pixel columns

(cols=pitch)

VIDEO_VISIBLE_ROWSvisible pixel rows

VIDEO_PIXEL_SIZEbytes per pixel

VIDEO_DATA_FORMATgraphic data format

(0-5, cf. cfb_console.c)

VIDEO_FB_ADRSframebuffer address

VIDEO_KBD_INIT_FCTkeyboard int fct

(i.e. i8042_kbd_init())

VIDEO_TSTC_FCTtest char fct

(i.e. i8042_tstc)

VIDEO_GETC_FCTget char fct

(i.e. i8042_getc)

CONFIG_CONSOLE_CURSORcursor drawing on/off

(requires blink timer

cf. i8042.c)

CONFIG_SYS_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)

CONFIG_CONSOLE_TIMEdisplay time/date info in

upper right corner

(requires CONFIG_CMD_DATE)

CONFIG_VIDEO_LOGOdisplay Linux logo in

upper left corner

CONFIG_VIDEO_BMP_LOGOuse bmp_logo.h instead of

linux_logo.h for logo.

Requires CONFIG_VIDEO_LOGO

CONFIG_CONSOLE_EXTRA_INFO

additional board info beside

the logo


When CONFIG_CFB_CONSOLE is defined, video console is

default i/o. Serial console can be forced with

environment ‘console=serial‘.视频控制台默认的I / O的串行控制台可以强制环境控制台=串行”。


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.


- 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.


- Boot Delay:CONFIG_BOOTDELAY - in seconds

Delay before automatically booting the default image;

set to -1 to disable autoboot.


See doc/README.autoboot for these options that

work with CONFIG_BOOTDELAY. None are required.

CONFIG_BOOT_RETRY_TIME

CONFIG_BOOT_RETRY_MIN

CONFIG_AUTOBOOT_KEYED

CONFIG_AUTOBOOT_PROMPT

CONFIG_AUTOBOOT_DELAY_STR

CONFIG_AUTOBOOT_STOP_STR

CONFIG_AUTOBOOT_DELAY_STR2

CONFIG_AUTOBOOT_STOP_STR2

CONFIG_ZERO_BOOTDELAY_CHECK

CONFIG_RESET_TO_RETRY


- 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.


- 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 using "config_cmd_default.h"

and augmenting with additional #define‘s

for wanted commands.


The default command configuration includes all commands

except those marked below with a "*".


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_CACHE* icache, dcache

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_ELF* bootelf, bootvx

CONFIG_CMD_EXPORTENV* export the environment

CONFIG_CMD_SAVEENV  saveenv

CONFIG_CMD_FDC* Floppy Disk Support

CONFIG_CMD_FAT* FAT partition support

CONFIG_CMD_FDOS* Dos diskette Support

CONFIG_CMD_FLASH  flinfo, erase, protect

CONFIG_CMD_FPGA  FPGA device initialization support

CONFIG_CMD_GO* the ‘go‘ command (exec code)

CONFIG_CMD_GREPENV* search environment

CONFIG_CMD_HWFLOW* RTS/CTS hw flow control

CONFIG_CMD_I2C* I2C serial bus support

CONFIG_CMD_IDE* IDE harddisk support

CONFIG_CMD_IMI  iminfo

CONFIG_CMD_IMLS  List all found images

CONFIG_CMD_IMMAP* IMMR dump support

CONFIG_CMD_IMPORTENV* import an environment

CONFIG_CMD_IRQ* irqinfo

CONFIG_CMD_ITEST  Integer/string test of 2 values

CONFIG_CMD_JFFS2* JFFS2 Support

CONFIG_CMD_KGDB* kgdb

CONFIG_CMD_LDRINFO  ldrinfo (display Blackfin loader)

CONFIG_CMD_LOADB  loadb

CONFIG_CMD_LOADS  loads

CONFIG_CMD_MD5SUM  print md5 message digest

  (requires CONFIG_CMD_MEMORY and CONFIG_MD5)

CONFIG_CMD_MEMORY  md, mm, nm, mw, cp, cmp, crc, base,

  loop, loopw, mtest

CONFIG_CMD_MISC  Misc functions like sleep etc

CONFIG_CMD_MMC* MMC memory mapped support

CONFIG_CMD_MII* MII utility commands

CONFIG_CMD_MTDPARTS* MTD partition support

CONFIG_CMD_NAND* NAND support

CONFIG_CMD_NET  bootp, tftpboot, rarpboot

CONFIG_CMD_PCA953X* PCA953x I2C gpio commands

CONFIG_CMD_PCA953X_INFO* PCA953x I2C gpio info command

CONFIG_CMD_PCI* pciinfo

CONFIG_CMD_PCMCIA* PCMCIA support

CONFIG_CMD_PING* send ICMP ECHO_REQUEST to network

  host

CONFIG_CMD_PORTIO* Port I/O

CONFIG_CMD_REGINFO* Register dump

CONFIG_CMD_RUN  run command in env variable

CONFIG_CMD_SAVES* save S record dump

CONFIG_CMD_SCSI* SCSI Support

CONFIG_CMD_SDRAM* print SDRAM configuration information

  (requires CONFIG_CMD_I2C)

CONFIG_CMD_SETGETDCR  Support for DCR Register access

  (4xx only)

CONFIG_CMD_SHA1SUM  print sha1 memory digest

  (requires CONFIG_CMD_MEMORY)

CONFIG_CMD_SOURCE  "source" command Support

CONFIG_CMD_SPI* SPI serial bus support

CONFIG_CMD_TFTPSRV* TFTP transfer in server mode

CONFIG_CMD_USB* USB support

CONFIG_CMD_CDP* Cisco Discover Protocol support

CONFIG_CMD_FSL* Microblaze FSL support



EXAMPLE: If you want all functions except of network

support you can write:


#include "config_cmd_all.h"

#undef CONFIG_CMD_NET


Other Commands:

fdt (flattened device tree) command: CONFIG_OF_LIBFDT


Note:Don‘t enable the "icache" and "dcache" commands

(configuration option CONFIG_CMD_CACHE) unless you know

what you (and your U-Boot users) are doing. Data

cache cannot be enabled on systems like the 8xx or

8260 (where accesses to the IMMR region must be

uncached), and it cannot be disabled on all other

systems where we (mis-) use the data cache to hold an

initial stack and some data.



XXX - this list needs to get updated!


- Watchdog:

CONFIG_WATCHDOG

If this variable is defined, it enables watchdog

support for the SoC. There must be support in the SoC

specific code for a watchdog. For the 8xx and 8260

CPUs, the SIU Watchdog feature is enabled in the SYPCR

register.  When supported for a specific SoC is

available, then no further board specific code should

be needed to use it.


CONFIG_HW_WATCHDOG

When using a watchdog circuitry external to the used

SoC, then define this variable and provide board

specific code for the "hw_watchdog_reset" function.


- U-Boot Version:

CONFIG_VERSION_VARIABLE

If this variable is defined, an environment variable

named "ver" is created by U-Boot showing the U-Boot

version as printed by the "version" command.

This variable is readonly.


- Real-Time Clock:


When CONFIG_CMD_DATE is selected, the type of the RTC

has to be selected, too. Define exactly one of the

following options:


CONFIG_RTC_MPC8xx- use internal RTC of MPC8xx

CONFIG_RTC_PCF8563- use Philips PCF8563 RTC

CONFIG_RTC_MC13783- use MC13783 RTC

CONFIG_RTC_MC146818- use MC146818 RTC

CONFIG_RTC_DS1307- use Maxim, Inc. DS1307 RTC

CONFIG_RTC_DS1337- use Maxim, Inc. DS1337 RTC

CONFIG_RTC_DS1338- use Maxim, Inc. DS1338 RTC

CONFIG_RTC_DS164x- use Dallas DS164x RTC

CONFIG_RTC_ISL1208- use Intersil ISL1208 RTC

CONFIG_RTC_MAX6900- use Maxim, Inc. MAX6900 RTC

CONFIG_SYS_RTC_DS1337_NOOSC- Turn off the OSC output for DS1337

CONFIG_SYS_RV3029_TCR- enable trickle charger on

  RV3029 RTC.


Note that if the RTC uses I2C, then the I2C interface

must also be configured. See I2C Support, below.


- GPIO Support:

CONFIG_PCA953X- use NXP‘s PCA953X series I2C GPIO

CONFIG_PCA953X_INFO- enable pca953x info command


The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of

chip-ngpio pairs that tell the PCA953X driver the number of

pins supported by a particular chip.


Note that if the GPIO device uses I2C, then the I2C interface

must also be configured. See I2C Support, below.


- Timestamp Support:


When CONFIG_TIMESTAMP is selected, the timestamp

(date and time) of an image is printed by image

commands like bootm or iminfo. This option is

automatically enabled when you select CONFIG_CMD_DATE .


- Partition Support:

CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION

and/or CONFIG_ISO_PARTITION and/or CONFIG_EFI_PARTITION


If IDE or SCSI support is enabled (CONFIG_CMD_IDE or

CONFIG_CMD_SCSI) you must configure support for at

least one partition type as well.


- IDE Reset method:

CONFIG_IDE_RESET_ROUTINE - this is defined in several

board configurations files but used nowhere!


CONFIG_IDE_RESET - is this is defined, IDE Reset will

be performed by calling the function

ide_set_reset(int reset)

which has to be defined in a board specific file


- ATAPI Support:

CONFIG_ATAPI


Set this to enable ATAPI support.


- LBA48 Support

CONFIG_LBA48


Set this to enable support for disks larger than 137GB

Also look at CONFIG_SYS_64BIT_LBA.

Whithout these , LBA48 support uses 32bit variables and will ‘only‘

support disks up to 2.1TB.


CONFIG_SYS_64BIT_LBA:

When enabled, makes the IDE subsystem use 64bit sector addresses.

Default is 32bit.


- SCSI Support:

At the moment only there is only support for the

SYM53C8XX SCSI controller; define

CONFIG_SCSI_SYM53C8XX to enable it.


CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and

CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *

CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the

maximum numbers of LUNs, SCSI ID‘s and target

devices.

CONFIG_SYS_SCSI_SYM53C8XX_CCF to fix clock timing (80Mhz)


- NETWORK Support (PCI):

CONFIG_E1000

Support for Intel 8254x gigabit chips.


CONFIG_E1000_FALLBACK_MAC

default MAC for empty EEPROM after production.


CONFIG_EEPRO100

Support for Intel 82557/82559/82559ER chips.

Optional CONFIG_EEPRO100_SROM_WRITE enables EEPROM

write routine for first time initialisation.


CONFIG_TULIP

Support for Digital 2114x chips.

Optional CONFIG_TULIP_SELECT_MEDIA for board specific

modem chip initialisation (KS8761/QS6611).


CONFIG_NATSEMI

Support for National dp83815 chips.


CONFIG_NS8382X

Support for National dp8382[01] gigabit chips.


- NETWORK Support (other):


CONFIG_DRIVER_AT91EMAC

Support for AT91RM9200 EMAC.


CONFIG_RMII

Define this to use reduced MII inteface


CONFIG_DRIVER_AT91EMAC_QUIET

If this defined, the driver is quiet.

The driver doen‘t show link status messages.


CONFIG_DRIVER_LAN91C96

Support for SMSC‘s LAN91C96 chips.


CONFIG_LAN91C96_BASE

Define this to hold the physical address

of the LAN91C96‘s I/O space


CONFIG_LAN91C96_USE_32_BIT

Define this to enable 32 bit addressing


CONFIG_DRIVER_SMC91111

Support for SMSC‘s LAN91C111 chip


CONFIG_SMC91111_BASE

Define this to hold the physical address

of the device (I/O space)


CONFIG_SMC_USE_32_BIT

Define this if data bus is 32 bits


CONFIG_SMC_USE_IOFUNCS

Define this to use i/o functions instead of macros

(some hardware wont work with macros)


CONFIG_FTGMAC100

Support for Faraday‘s FTGMAC100 Gigabit SoC Ethernet


CONFIG_FTGMAC100_EGIGA

Define this to use GE link update with gigabit PHY.

Define this if FTGMAC100 is connected to gigabit PHY.

If your system has 10/100 PHY only, it might not occur

wrong behavior. Because PHY usually return timeout or

useless data when polling gigabit status and gigabit

control registers. This behavior won‘t affect the

correctnessof 10/100 link speed update.


CONFIG_SMC911X

Support for SMSC‘s LAN911x and LAN921x chips


CONFIG_SMC911X_BASE

Define this to hold the physical address

of the device (I/O space)


CONFIG_SMC911X_32_BIT

Define this if data bus is 32 bits


CONFIG_SMC911X_16_BIT

Define this if data bus is 16 bits. If your processor

automatically converts one 32 bit word to two 16 bit

words you may also try CONFIG_SMC911X_32_BIT.


CONFIG_SH_ETHER

Support for Renesas on-chip Ethernet controller


CONFIG_SH_ETHER_USE_PORT

Define the number of ports to be used


CONFIG_SH_ETHER_PHY_ADDR

Define the ETH PHY‘s address


CONFIG_SH_ETHER_CACHE_WRITEBACK

If this option is set, the driver enables cache flush.


- USB Support:

At the moment only the UHCI host controller is

supported (PIP405, MIP405, MPC5200); define

CONFIG_USB_UHCI to enable it.

define CONFIG_USB_KEYBOARD to enable the USB Keyboard

and define CONFIG_USB_STORAGE to enable the USB

storage devices.

Note:

Supported are USB Keyboards and USB Floppy drives

(TEAC FD-05PUB).

MPC5200 USB requires additional defines:

CONFIG_USB_CLOCK

for 528 MHz Clock: 0x0001bbbb

CONFIG_PSC3_USB

for USB on PSC3

CONFIG_USB_CONFIG

for differential drivers: 0x00001000

for single ended drivers: 0x00005000

for differential drivers on PSC3: 0x00000100

for single ended drivers on PSC3: 0x00004100

CONFIG_SYS_USB_EVENT_POLL

May be defined to allow interrupt polling

instead of using asynchronous interrupts


- USB Device:

Define the below if you wish to use the USB console.

Once firmware is rebuilt from a serial console issue the

command "setenv stdin usbtty; setenv stdout usbtty" and

attach your USB cable. The Unix command "dmesg" should print

it has found a new device. The environment variable usbtty

can be set to gserial or cdc_acm to enable your device to

appear to a USB host as a Linux gserial device or a

Common Device Class Abstract Control Model serial device.

If you select usbtty = gserial you should be able to enumerate

a Linux host by

# modprobe usbserial vendor=0xVendorID product=0xProductID

else if using cdc_acm, simply setting the environment

variable usbtty to be cdc_acm should suffice. The following

might be defined in YourBoardName.h


CONFIG_USB_DEVICE

Define this to build a UDC device


CONFIG_USB_TTY

Define this to have a tty type of device available to

talk to the UDC device


CONFIG_SYS_CONSOLE_IS_IN_ENV

Define this if you want stdin, stdout &/or stderr to

be set to usbtty.


mpc8xx:

CONFIG_SYS_USB_EXTC_CLK 0xBLAH

Derive USB clock from external clock "blah"

- CONFIG_SYS_USB_EXTC_CLK 0x02


CONFIG_SYS_USB_BRG_CLK 0xBLAH

Derive USB clock from brgclk

- CONFIG_SYS_USB_BRG_CLK 0x04


If you have a USB-IF assigned VendorID then you may wish to

define your own vendor specific values either in BoardName.h

or directly in usbd_vendor_info.h. If you don‘t define

CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,

CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot

should pretend to be a Linux device to it‘s target host.


CONFIG_USBD_MANUFACTURER

Define this string as the name of your company for

- CONFIG_USBD_MANUFACTURER "my company"


CONFIG_USBD_PRODUCT_NAME

Define this string as the name of your product

- CONFIG_USBD_PRODUCT_NAME "acme usb device"


CONFIG_USBD_VENDORID

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



- MMC Support:

The MMC controller on the Intel PXA is supported. To

enable this define CONFIG_MMC. The MMC can be

accessed from the boot prompt by mapping the device

to physical memory similar to flash. Command line is

enabled with CONFIG_CMD_MMC. The MMC driver also works with

the FAT fs. This is enabled with CONFIG_CMD_FAT.


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


- Journaling Flash filesystem support:

CONFIG_JFFS2_NAND, CONFIG_JFFS2_NAND_OFF, CONFIG_JFFS2_NAND_SIZE,

CONFIG_JFFS2_NAND_DEV

Define these for a default partition on a NAND device


CONFIG_SYS_JFFS2_FIRST_SECTOR,

CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS

Define these for a default partition on a NOR device


CONFIG_SYS_JFFS_CUSTOM_PART

Define this to create an own partition. You have to provide a

function struct part_info* jffs2_part_info(int part_num)


If you define only one JFFS2 partition you may also want to

#define CONFIG_SYS_JFFS_SINGLE_PART1

to disable the command chpart. This is the default when you

have not defined a custom partition


- Keyboard Support:

CONFIG_ISA_KEYBOARD


Define this to enable standard (PC-Style) keyboard

support


CONFIG_I8042_KBD

Standard PC keyboard driver with US (is default) and

GERMAN key layout (switch via environment ‘keymap=de‘) support.

Export function i8042_kbd_init, i8042_tstc and i8042_getc

for cfb_console. Supports cursor blinking.


- Video support:

CONFIG_VIDEO


Define this to enable video support (for output to

video).


CONFIG_VIDEO_CT69000


Enable Chips & Technologies 69000 Video chip


CONFIG_VIDEO_SMI_LYNXEM

Enable Silicon Motion SMI 712/710/810 Video chip. The

video output is selected via environment ‘videoout‘

(1 = LCD and 2 = CRT). If videoout is undefined, CRT is

assumed.


For the CT69000 and SMI_LYNXEM drivers, videomode is

selected via environment ‘videomode‘. Two different ways

are possible:

- "videomode=num"   ‘num‘ is a standard LiLo mode numbers.

Following standard modes are supported(* is default):


      Colors640x480 800x600 1024x768 1152x864 1280x1024

-------------+---------------------------------------------

      8 bits |0x301* 0x303 0x305   0x161    0x307

     15 bits |0x310 0x313 0x316   0x162    0x319

     16 bits |0x311 0x314 0x317   0x163    0x31A

     24 bits |0x312 0x315 0x318     ?    0x31B

-------------+---------------------------------------------

(i.e. setenv videomode 317; saveenv; reset;)


- "videomode=bootargs" all the video parameters are parsed

from the bootargs. (See drivers/video/videomodes.c)



CONFIG_VIDEO_SED13806

Enable Epson SED13806 driver. This driver supports 8bpp

and 16bpp modes defined by CONFIG_VIDEO_SED13806_8BPP

or CONFIG_VIDEO_SED13806_16BPP


CONFIG_FSL_DIU_FB

Enable the Freescale DIU video driver.Reference boards for

SOCs that have a DIU should define this macro to enable DIU

support, and should also define these other macros:


CONFIG_SYS_DIU_ADDR

CONFIG_VIDEO

CONFIG_CMD_BMP

CONFIG_CFB_CONSOLE

CONFIG_VIDEO_SW_CURSOR

CONFIG_VGA_AS_SINGLE_DEVICE

CONFIG_VIDEO_LOGO

CONFIG_VIDEO_BMP_LOGO


The DIU driver will look for the ‘video-mode‘ environment

variable, and if defined, enable the DIU as a console during

boot.  See the documentation file README.video for a

description of this variable.


- Keyboard Support:

CONFIG_KEYBOARD


Define this to enable a custom keyboard support.

This simply calls drv_keyboard_init() which must be

defined in your board-specific files.

The only board using this so far is RBC823.


- LCD Support:CONFIG_LCD


Define this to enable LCD support (for output to LCD

display); also select one of the supported displays

by defining one of these:


CONFIG_ATMEL_LCD:


HITACHI TX09D70VM1CCA, 3.5", 240x320.


CONFIG_NEC_NL6448AC33:


NEC NL6448AC33-18. Active, color, single scan.


CONFIG_NEC_NL6448BC20


NEC NL6448BC20-08. 6.5", 640x480.

Active, color, single scan.


CONFIG_NEC_NL6448BC33_54


NEC NL6448BC33-54. 10.4", 640x480.

Active, color, single scan.


CONFIG_SHARP_16x9


Sharp 320x240. Active, color, single scan.

It isn‘t 16x9, and I am not sure what it is.


CONFIG_SHARP_LQ64D341


Sharp LQ64D341 display, 640x480.

Active, color, single scan.


CONFIG_HLD1045


HLD1045 display, 640x480.

Active, color, single scan.


CONFIG_OPTREX_BW


Optrex CBL50840-2 NF-FW 99 22 M5

or

Hitachi LMG6912RPFC-00T

or

Hitachi SP14Q002


320x240. Black & white.


Normally display is black on white background; define

CONFIG_SYS_WHITE_ON_BLACK to get it inverted.


- Splash Screen Support: CONFIG_SPLASH_SCREEN


If this option is set, the environment is checked for

a variable "splashimage". If found, the usual display

of logo, copyright and system information on the LCD

is suppressed and the BMP image at the address

specified in "splashimage" is loaded instead. The

console is redirected to the "nulldev", too. This

allows for a "silent" boot where a splash screen is

loaded very quickly after power-on.


CONFIG_SPLASH_SCREEN_ALIGN


If this option is set the splash image can be freely positioned

on the screen. Environment variable "splashpos" specifies the

position as "x,y". If a positive number is given it is used as

number of pixel from left/top. If a negative number is given it

is used as number of pixel from right/bottom. You can also

specify ‘m‘ for centering the image.


Example:

setenv splashpos m,m

=> image at center of screen


setenv splashpos 30,20

=> image at x = 30 and y = 20


setenv splashpos -10,m

=> vertically centered image

   at x = dspWidth - bmpWidth - 9


- Gzip compressed BMP image support: CONFIG_VIDEO_BMP_GZIP


If this option is set, additionally to standard BMP

images, gzipped BMP images can be displayed via the

splashscreen support or the bmp command.


- Run length encoded BMP image (RLE8) support: CONFIG_VIDEO_BMP_RLE8


If this option is set, 8-bit RLE compressed BMP images

can be displayed via the splashscreen support or the

bmp command.


- Compression support:

CONFIG_BZIP2


If this option is set, support for bzip2 compressed

images is included. If not, only uncompressed and gzip

compressed images are supported.


NOTE: the bzip2 algorithm requires a lot of RAM, so

the malloc area (as defined by CONFIG_SYS_MALLOC_LEN) should

be at least 4MB.


CONFIG_LZMA


If this option is set, support for lzma compressed

images is included.


Note: The LZMA algorithm adds between 2 and 4KB of code and it

requires an amount of dynamic memory that is given by the

formula:


(1846 + 768 << (lc + lp)) * sizeof(uint16)


Where lc and lp stand for, respectively, Literal context bits

and Literal pos bits.


This value is upper-bounded by 14MB in the worst case. Anyway,

for a ~4MB large kernel image, we have lc=3 and lp=0 for a

total amount of (1846 + 768 << (3 + 0)) * 2 = ~41KB... that is

a very small buffer.


Use the lzmainfo tool to determinate the lc and lp values and

then calculate the amount of needed dynamic memory (ensuring

the appropriate CONFIG_SYS_MALLOC_LEN value).


- MII/PHY support:

CONFIG_PHY_ADDR


The address of PHY on MII bus.


CONFIG_PHY_CLOCK_FREQ (ppc4xx)


The clock frequency of the MII bus


CONFIG_PHY_GIGE


If this option is set, support for speed/duplex

detection of gigabit PHY is included.


CONFIG_PHY_RESET_DELAY


Some PHY like Intel LXT971A need extra delay after

reset before any MII register access is possible.

For such PHY, set this option to the usec delay

required. (minimum 300usec for LXT971A)


CONFIG_PHY_CMD_DELAY (ppc4xx)


Some PHY like Intel LXT971A need extra delay after

command issued before MII status register can be read


- Ethernet address:

CONFIG_ETHADDR

CONFIG_ETH1ADDR

CONFIG_ETH2ADDR

CONFIG_ETH3ADDR

CONFIG_ETH4ADDR

CONFIG_ETH5ADDR


Define a default value for Ethernet address to use

for the respective Ethernet interface, in case this

is not determined automatically.


- IP address:

CONFIG_IPADDR


Define a default value for the IP address to use for

the default Ethernet interface, in case this is not

determined through e.g. bootp.


- Server IP address:

CONFIG_SERVERIP


Defines a default value for the IP address of a TFTP

server to contact when using the "tftboot" command.


CONFIG_KEEP_SERVERADDR


Keeps the server‘s MAC address, in the env ‘serveraddr‘

for passing to bootargs (like Linux‘s netconsole option)


- Multicast TFTP Mode:

CONFIG_MCAST_TFTP


Defines whether you want to support multicast TFTP as per

rfc-2090; for example to work with atftp.  Lets lots of targets

tftp down the same boot image concurrently.  Note: the Ethernet

driver in use must provide a function: mcast() to join/leave a

multicast group.


- 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


- DHCP Advanced Options:

You can fine tune the DHCP functionality by defining

CONFIG_BOOTP_* symbols:


CONFIG_BOOTP_SUBNETMASK

CONFIG_BOOTP_GATEWAY

CONFIG_BOOTP_HOSTNAME

CONFIG_BOOTP_NISDOMAIN

CONFIG_BOOTP_BOOTPATH

CONFIG_BOOTP_BOOTFILESIZE

CONFIG_BOOTP_DNS

CONFIG_BOOTP_DNS2

CONFIG_BOOTP_SEND_HOSTNAME

CONFIG_BOOTP_NTPSERVER

CONFIG_BOOTP_TIMEOFFSET

CONFIG_BOOTP_VENDOREX


CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip

environment variable, not the BOOTP server.


CONFIG_BOOTP_DNS2 - If a DHCP client requests the DNS

serverip from a DHCP server, it is possible that more

than one DNS serverip is offered to the client.

If CONFIG_BOOTP_DNS2 is enabled, the secondary DNS

serverip will be stored in the additional environment

variable "dnsip2". The first DNS serverip is always

stored in the variable "dnsip", when CONFIG_BOOTP_DNS

is defined.


CONFIG_BOOTP_SEND_HOSTNAME - Some DHCP servers are capable

to do a dynamic update of a DNS server. To do this, they

need the hostname of the DHCP requester.

If CONFIG_BOOTP_SEND_HOSTNAME is defined, the content

of the "hostname" environment variable is passed as

option 12 to the DHCP server.


CONFIG_BOOTP_DHCP_REQUEST_DELAY


A 32bit value in microseconds for a delay between

receiving a "DHCP Offer" and sending the "DHCP Request".

This fixes a problem with certain DHCP servers that don‘t

respond 100% of the time to a "DHCP request". E.g. On an

AT91RM9200 processor running at 180MHz, this delay needed

to be *at least* 15,000 usec before a Windows Server 2003

DHCP server would reply 100% of the time. I recommend at

least 50,000 usec to be safe. The alternative is to hope

that one of the retries will be successful but note that

the DHCP timeout and retry process takes a longer than

this delay.


 - 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_STATUS_LED


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_STATUS_LED enables this

feature in U-Boot.


- CAN Support:CONFIG_CAN_DRIVER


Defining CONFIG_CAN_DRIVER enables CAN driver support

on those systems that support this (optional)

feature, like the TQM8xxL modules.


- I2C Support:CONFIG_HARD_I2C | CONFIG_SOFT_I2C


These enable I2C serial bus commands. Defining either of

(but not both of) CONFIG_HARD_I2C or CONFIG_SOFT_I2C will

include the appropriate I2C driver for the selected CPU.


This will allow you to use i2c commands at the u-boot

command line (as long as you set CONFIG_CMD_I2C in

CONFIG_COMMANDS) and communicate with i2c based realtime

clock chips. See common/cmd_i2c.c for a description of the

command line interface.


CONFIG_HARD_I2C selects a hardware I2C controller.


CONFIG_SOFT_I2C configures u-boot to use a software (aka

bit-banging) driver instead of CPM or similar hardware

support for I2C.


There are several other quantities that must also be

defined when you define CONFIG_HARD_I2C or CONFIG_SOFT_I2C.


In both cases you will need to define CONFIG_SYS_I2C_SPEED

to be the frequency (in Hz) at which you wish your i2c bus

to run and CONFIG_SYS_I2C_SLAVE to be the address of this node (ie

the CPU‘s i2c node address).


Now, the u-boot i2c code for the mpc8xx

(arch/powerpc/cpu/mpc8xx/i2c.c) sets the CPU up as a master node

and so its address should therefore be cleared to 0 (See,

eg, MPC823e User‘s Manual p.16-473). So, set

CONFIG_SYS_I2C_SLAVE to 0.


CONFIG_SYS_I2C_INIT_MPC5XXX


When a board is reset during an i2c bus transfer

chips might think that the current transfer is still

in progress.  Reset the slave devices by sending start

commands until the slave device responds.


That‘s all that‘s required for CONFIG_HARD_I2C.


If you use the software i2c interface (CONFIG_SOFT_I2C)

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_PORT


(Only for MPC8260 CPU). The I/O port to use (the code

assumes both bits are on the same port). Valid values

are 0..3 for ports A..D.


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; \

elseimmr->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; \

elseimmr->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.


CONFIG_SYS_I2C_INIT_BOARD


When a board is reset during an i2c bus transfer

chips might think that the current transfer is still

in progress. On some boards it is possible to access

the i2c SCLK line directly, either by using the

processor pin as a GPIO or by having a second pin

connected to the bus. If this option is defined a

custom i2c_init_board() routine in boards/xxx/board.c

is run early in the boot sequence.


CONFIG_SYS_I2C_BOARD_LATE_INIT


An alternative to CONFIG_SYS_I2C_INIT_BOARD. If this option is

defined a custom i2c_board_late_init() routine in

boards/xxx/board.c is run AFTER the operations in i2c_init()

is completed. This callpoint can be used to unreset i2c bus

using CPU i2c controller register accesses for CPUs whose i2c

controller provide such a method. It is called at the end of

i2c_init() to allow i2c_init operations to setup the i2c bus

controller on the CPU (e.g. setting bus speed & slave address).


CONFIG_I2CFAST (PPC405GP|PPC405EP only)


This option enables configuration of bi_iic_fast[] flags

in u-boot bd_info structure based on u-boot environment

variable "i2cfast". (see also i2cfast)


CONFIG_I2C_MULTI_BUS


This option allows the use of multiple I2C buses, each of which

must have a controller.  At any point in time, only one bus is

active.  To switch to a different bus, use the ‘i2c dev‘ command.

Note that bus numbering is zero-based.


CONFIG_SYS_I2C_NOPROBES


This option specifies a list of I2C devices that will be skipped

when the ‘i2c probe‘ command is issued.  If CONFIG_I2C_MULTI_BUS

is set, specify a list of bus-device pairs.  Otherwise, specify

a 1D array of device addresses


e.g.

#undefCONFIG_I2C_MULTI_BUS

#define CONFIG_SYS_I2C_NOPROBES{0x50,0x68}


will skip addresses 0x50 and 0x68 on a board with one I2C bus


#defineCONFIG_I2C_MULTI_BUS

#define CONFIG_SYS_I2C_MULTI_NOPROBES{{0,0x50},{0,0x68},{1,0x54}}


will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1


CONFIG_SYS_SPD_BUS_NUM


If defined, then this indicates the I2C bus number for DDR SPD.

If not defined, then U-Boot assumes that SPD is on I2C bus 0.


CONFIG_SYS_RTC_BUS_NUM


If defined, then this indicates the I2C bus number for the RTC.

If not defined, then U-Boot assumes that RTC is on I2C bus 0.


CONFIG_SYS_DTT_BUS_NUM


If defined, then this indicates the I2C bus number for the DTT.

If not defined, then U-Boot assumes that DTT is on I2C bus 0.


CONFIG_SYS_I2C_DTT_ADDR:


If defined, specifies the I2C address of the DTT device.

If not defined, then U-Boot uses predefined value for

specified DTT device.


CONFIG_FSL_I2C


Define this option if you want to use Freescale‘s I2C driver in

drivers/i2c/fsl_i2c.c.


CONFIG_I2C_MUX


Define this option if you have I2C devices reached over 1 .. n

I2C Muxes like the pca9544a. This option addes a new I2C

Command "i2c bus [muxtype:muxaddr:muxchannel]" which adds a

new I2C Bus to the existing I2C Busses. If you select the

new Bus with "i2c dev", u-bbot sends first the commandos for

the muxes to activate this new "bus".


CONFIG_I2C_MULTI_BUS must be also defined, to use this

feature!


Example:

Adding a new I2C Bus reached over 2 pca9544a muxes

The First mux with address 70 and channel 6

The Second mux with address 71 and channel 4


=> i2c bus pca9544a:70:6:pca9544a:71:4


Use the "i2c bus" command without parameter, to get a list

of I2C Busses with muxes:


=> i2c bus

Busses reached over muxes:

Bus ID: 2

  reached over Mux(es):

    pca9544a@70 ch: 4

Bus ID: 3

  reached over Mux(es):

    pca9544a@70 ch: 6

    pca9544a@71 ch: 4

=>


If you now switch to the new I2C Bus 3 with "i2c dev 3"

u-boot first sends the command to the mux@70 to enable

channel 6, and then the command to the mux@71 to enable

the channel 4.


After that, you can use the "normal" i2c commands as

usual to communicate with your I2C devices behind

the 2 muxes.


This option is actually implemented for the bitbanging

algorithm in common/soft_i2c.c and for the Hardware I2C

Bus on the MPC8260. But it should be not so difficult

to add this option to other architectures.


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)


CONFIG_SH_SPI


Enables the driver for SPI controller on SuperH. Currently

only SH7757 is supported.


CONFIG_SPI_X


Enables extended (16-bit) SPI EEPROM addressing.

(symmetrical to CONFIG_I2C_X)


CONFIG_SOFT_SPI


Enables a software (bit-bang) SPI driver rather than

using hardware support. This is a general purpose

driver that only requires three general I/O port pins

(two outputs, one input) to function. If this is

defined, the board configuration must define several

SPI configuration items (port pins to use, etc). For

an example, see include/configs/sacsng.h.


CONFIG_HARD_SPI


Enables a hardware SPI driver for general-purpose reads

and writes.  As with CONFIG_SOFT_SPI, the board configuration

must define a list of chip-select function pointers.

Currently supported on some MPC8xxx processors.  For an

example, see include/configs/mpc8349emds.h.


CONFIG_MXC_SPI


Enables the driver for the SPI controllers on i.MX and MXC

SoCs. Currently only i.MX31 is supported.


- 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_FPGA_COUNT


Specify the number of FPGA devices to support.


CONFIG_SYS_FPGA_PROG_FEEDBACK


Enable printing of hash marks during FPGA configuration.


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.


CONFIG_FPGA_DELAY


If defined, a function that provides delays in the FPGA

configuration driver.


CONFIG_SYS_FPGA_CHECK_CTRLC

Allow Control-C to interrupt FPGA configuration


CONFIG_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).


CONFIG_SYS_FPGA_WAIT_INIT


Maximum time to wait for the INIT_B line to deassert

after PROB_B has been deasserted during a Virtex II

FPGA configuration sequence. The default time is 500

ms.


CONFIG_SYS_FPGA_WAIT_BUSY


Maximum time to wait for BUSY to deassert during

Virtex II FPGA configuration. The default is 5 ms.


CONFIG_SYS_FPGA_WAIT_CONFIG


Time to wait after FPGA configuration. The default is

200 ms.


- Configuration Management:

CONFIG_IDENT_STRING


If defined, this string will be added to the U-Boot

version information (U_BOOT_VERSION)


- 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.


Alternatively, if you #define _both_ CONFIG_ETHADDR

_and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default

Ethernet address is installed in the environment,

which can be changed exactly ONCE by the user. [The

serial# is unaffected by this, i. e. it remains

read-only.]


- Protected RAM:

CONFIG_PRAM


Define this variable to enable the reservation of

"protected RAM", i. e. RAM which is not overwritten

by U-Boot. Define CONFIG_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":


ETX094, IVMS8, IVML24, SPD8xx, TQM8xxL,

HERMES, IP860, RPXlite, LWMON, LANTEC,

FLAGADM, TQM8260


- Error Recovery:

CONFIG_PANIC_HANG


Define this variable to stop the system in case of a

fatal error, so that you have to reset it manually.

This is probably NOT a good idea for an embedded

system where you want the system to reboot

automatically as fast as possible, but it may be

useful during development since you can try to debug

the conditions that lead to the situation.


CONFIG_NET_RETRY_COUNT


This variable defines the number of retries for

network operations like ARP, RARP, TFTP, or BOOTP

before giving up the operation. If not defined, a

default value of 5 is used.


CONFIG_ARP_TIMEOUT


Timeout waiting for an ARP reply in milliseconds.


- Command Interpreter:

CONFIG_AUTO_COMPLETE


Enable auto completion of commands using TAB.


Note that this feature has NOT been implemented yet

for the "hush" shell.



CONFIG_SYS_HUSH_PARSER


Define this variable to enable the "hush" shell (from

Busybox) as command line interpreter, thus enabling

powerful command line syntax like

if...then...else...fi conditionals or `&&‘ and ‘||‘

constructs ("shell scripts").


If undefined, you get the old, much simpler behaviour

with a somewhat smaller memory footprint.



CONFIG_SYS_PROMPT_HUSH_PS2


This defines the secondary prompt string, which is

printed when the command interpreter needs more input

to complete a command. Usually "> ".


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.


- Commandline Editing and History:

CONFIG_CMDLINE_EDITING


Enable editing and History functions for interactive

commandline input operations


- Default Environment:

CONFIG_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 CONFIG_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.


- DataFlash Support:

CONFIG_HAS_DATAFLASH


Defining this option enables DataFlash features and

allows to read/write in Dataflash via the standard

commands cp, md...


- SystemACE Support:

CONFIG_SYSTEMACE


Adding this option adds support for Xilinx SystemACE

chips attached via some sort of local bus. The address

of the chip must also be defined in the

CONFIG_SYS_SYSTEMACE_BASE macro. For example:


#define CONFIG_SYSTEMACE

#define CONFIG_SYS_SYSTEMACE_BASE 0xf0000000


When SystemACE support is added, the "ace" device type

becomes available to the fat commands, i.e. fatls.


- TFTP Fixed UDP Port:

CONFIG_TFTP_PORT


If this is defined, the environment variable tftpsrcp

is used to supply the TFTP UDP source port value.

If tftpsrcp isn‘t defined, the normal pseudo-random port

number generator is used.


Also, the environment variable tftpdstp is used to supply

the TFTP UDP destination port value.  If tftpdstp isn‘t

defined, the normal port 69 is used.


The purpose for tftpsrcp is to allow a TFTP server to

blindly start the TFTP transfer using the pre-configured

target IP address and UDP port. This has the effect of

"punching through" the (Windows XP) firewall, allowing

the remainder of the TFTP transfer to proceed normally.

A better solution is to properly configure the firewall,

but sometimes that is not allowed.


- Show boot progress:

CONFIG_SHOW_BOOT_PROGRESS


Defining this option allows to add some board-

specific code (calling a user-provided function

"show_boot_progress(int)") that enables you to show

the system‘s boot progress on some display (for

example, some LED‘s) on your board. At the moment,

the following checkpoints are implemented:


- Standalone program support:

CONFIG_STANDALONE_LOAD_ADDR


This option allows to define board specific values

for the address where standalone program gets loaded,

thus overwriting the architecutre dependent default

settings.


- Frame Buffer Address:

CONFIG_FB_ADDR


Define CONFIG_FB_ADDR if you want to use specific address for

frame buffer.

Then system will reserve the frame buffer address to defined address

instead of lcd_setmem (this function grab the memory for frame buffer

by panel‘s size).


Please see board_init_f function.


If you want this config option then,

please define it at your board config file


遗留的uImage格式:
  ArgWhere When
    1common/cmd_bootm.c before attempting to boot an image
   -1common/cmd_bootm.c Image header has bad magic number
    2common/cmd_bootm.c Image header has correct magic number
   -2common/cmd_bootm.c Image header has bad checksum
    3common/cmd_bootm.c Image header has correct checksum
   -3common/cmd_bootm.c Image data   has bad checksum
    4common/cmd_bootm.c Image data   has correct checksum
   -4common/cmd_bootm.c Image is for unsupported architecture
    5common/cmd_bootm.c Architecture check OK
   -5common/cmd_bootm.c Wrong Image Type (not kernel, multi)
    6common/cmd_bootm.c Image Type check OK
   -6common/cmd_bootm.c gunzip uncompression error
   -7common/cmd_bootm.c Unimplemented compression type
    7common/cmd_bootm.c Uncompression OK
    8common/cmd_bootm.c No uncompress/copy overwrite error
   -9common/cmd_bootm.c Unsupported OS (not Linux, BSD, VxWorks, QNX)

    9common/image.c Start initial ramdisk verification
  -10common/image.c Ramdisk header has bad   magic number
  -11common/image.c Ramdisk header has bad   checksum
   10common/image.c Ramdisk header is OK
  -12common/image.c Ramdisk data   has bad   checksum
   11common/image.c Ramdisk data   has correct checksum
   12common/image.c Ramdisk verification complete, start loading
  -13common/image.c Wrong Image Type (not PPC Linux ramdisk)
   13common/image.c Start multifile image verification
   14common/image.c No initial ramdisk, no multifile, continue.

   15arch/<arch>/lib/bootm.c All preparation done, transferring control to OS

  -30arch/powerpc/lib/board.c Fatal error, hang the system
  -31post/post.c POST test failed, detected by post_output_backlog()
  -32post/post.c POST test failed, detected by post_run_single()

   34common/cmd_doc.c before loading a Image from a DOC device
  -35common/cmd_doc.c Bad usage of "doc" command
   35common/cmd_doc.c correct usage of "doc" command
  -36common/cmd_doc.c No boot device
   36common/cmd_doc.c correct boot device
  -37common/cmd_doc.c Unknown Chip ID on boot device
   37common/cmd_doc.c correct chip ID found, device available
  -38common/cmd_doc.c Read Error on boot device
   38common/cmd_doc.c reading Image header from DOC device OK
  -39common/cmd_doc.c Image header has bad magic number
   39common/cmd_doc.c Image header has correct magic number
  -40common/cmd_doc.c Error reading Image from DOC device
   40common/cmd_doc.c Image header has correct magic number
   41common/cmd_ide.c before loading a Image from a IDE device
  -42common/cmd_ide.c Bad usage of "ide" command
   42common/cmd_ide.c correct usage of "ide" command
  -43common/cmd_ide.c No boot device
   43common/cmd_ide.c boot device found
  -44common/cmd_ide.c Device not available
   44common/cmd_ide.c Device available
  -45common/cmd_ide.c wrong partition selected
   45common/cmd_ide.c partition selected
  -46common/cmd_ide.c Unknown partition table
   46common/cmd_ide.c valid partition table found
  -47common/cmd_ide.c Invalid partition type
   47common/cmd_ide.c correct partition type
  -48common/cmd_ide.c Error reading Image Header on boot device
   48common/cmd_ide.c reading Image Header from IDE device OK
  -49common/cmd_ide.c Image header has bad magic number
   49common/cmd_ide.c Image header has correct magic number
  -50common/cmd_ide.c Image header has bad checksum
   50common/cmd_ide.c Image header has correct checksum
  -51common/cmd_ide.c Error reading Image from IDE device
   51common/cmd_ide.c reading Image from IDE device OK
   52common/cmd_nand.c before loading a Image from a NAND device
  -53common/cmd_nand.c Bad usage of "nand" command
   53common/cmd_nand.c correct usage of "nand" command
  -54common/cmd_nand.c No boot device
   54common/cmd_nand.c boot device found
  -55common/cmd_nand.c Unknown Chip ID on boot device
   55common/cmd_nand.c correct chip ID found, device available
  -56common/cmd_nand.c Error reading Image Header on boot device
   56common/cmd_nand.c reading Image Header from NAND device OK
  -57common/cmd_nand.c Image header has bad magic number
   57common/cmd_nand.c Image header has correct magic number
  -58common/cmd_nand.c Error reading Image from NAND device
   58common/cmd_nand.c reading Image from NAND device OK

  -60common/env_common.c Environment has a bad CRC, using default

   64net/eth.c starting with Ethernet configuration.
  -64net/eth.c no Ethernet found.
   65net/eth.c Ethernet found.

  -80common/cmd_net.c usage wrong
   80common/cmd_net.c before calling NetLoop()
  -81common/cmd_net.c some error in NetLoop() occurred
   81common/cmd_net.c NetLoop() back without error
  -82common/cmd_net.c size == 0 (File with size 0 loaded)
   82common/cmd_net.c trying automatic boot
   83common/cmd_net.c running "source" command
  -83common/cmd_net.c some error in automatic boot or "source" command
   84common/cmd_net.c end without errors
适合uImage格式:
 ArgWhere When
  100common/cmd_bootm.c Kernel FIT Image has correct format
 -100common/cmd_bootm.c Kernel FIT Image has incorrect format
  101common/cmd_bootm.c No Kernel subimage unit name, using configuration
 -101common/cmd_bootm.c Can‘t get configuration for kernel subimage
  102common/cmd_bootm.c Kernel unit name specified
 -103common/cmd_bootm.c Can‘t get kernel subimage node offset
  103common/cmd_bootm.c Found configuration node
  104common/cmd_bootm.c Got kernel subimage node offset
 -104common/cmd_bootm.c Kernel subimage hash verification failed
  105common/cmd_bootm.c Kernel subimage hash verification OK
 -105common/cmd_bootm.c Kernel subimage is for unsupported architecture
  106common/cmd_bootm.c Architecture check OK
 -106common/cmd_bootm.c Kernel subimage has wrong type
  107common/cmd_bootm.c Kernel subimage type OK
 -107common/cmd_bootm.c Can‘t get kernel subimage data/size
  108common/cmd_bootm.c Got kernel subimage data/size
 -108common/cmd_bootm.c Wrong image type (not legacy, FIT)
 -109common/cmd_bootm.c Can‘t get kernel subimage type
 -110common/cmd_bootm.c Can‘t get kernel subimage comp
 -111common/cmd_bootm.c Can‘t get kernel subimage os
 -112common/cmd_bootm.c Can‘t get kernel subimage load address
 -113common/cmd_bootm.c Image uncompress/copy overwrite error

  120common/image.c Start initial ramdisk verification
 -120common/image.c Ramdisk FIT image has incorrect format
  121common/image.c Ramdisk FIT image has correct format
  122common/image.c No ramdisk subimage unit name, using configuration
 -122common/image.c Can‘t get configuration for ramdisk subimage
  123common/image.c Ramdisk unit name specified
 -124common/image.c Can‘t get ramdisk subimage node offset
  125common/image.c Got ramdisk subimage node offset
 -125common/image.c Ramdisk subimage hash verification failed
  126common/image.c Ramdisk subimage hash verification OK
 -126common/image.c Ramdisk subimage for unsupported architecture
  127common/image.c Architecture check OK
 -127common/image.c Can‘t get ramdisk subimage data/size
  128common/image.c Got ramdisk subimage data/size
  129common/image.c Can‘t get ramdisk load address
 -129common/image.c Got ramdisk load address

 -130common/cmd_doc.c Incorrect FIT image format
  131common/cmd_doc.c FIT image format OK

 -140common/cmd_ide.c Incorrect FIT image format
  141common/cmd_ide.c FIT image format OK

 -150common/cmd_nand.c Incorrect FIT image format
  151common/cmd_nand.c FIT image format OK

- 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_DEVICE

Adds the MTD device infrastructure from the Linux kernel.
Needed for mtdparts command support.

CONFIG_MTD_PARTITIONS

Adds the MTD partitioning infrastructure from the Linux
kernel. Needed for UBI support.

- SPL framework
CONFIG_SPL
Enable building of SPL globally.

CONFIG_SPL_TEXT_BASE
TEXT_BASE for linking the SPL binary.

CONFIG_SPL_LDSCRIPT
LDSCRIPT for linking the SPL binary.

CONFIG_SPL_LIBCOMMON_SUPPORT
Support for common/libcommon.o in SPL binary

CONFIG_SPL_LIBDISK_SUPPORT
Support for disk/libdisk.o in SPL binary

CONFIG_SPL_I2C_SUPPORT
Support for drivers/i2c/libi2c.o in SPL binary

CONFIG_SPL_GPIO_SUPPORT
Support for drivers/gpio/libgpio.o in SPL binary

CONFIG_SPL_MMC_SUPPORT
Support for drivers/mmc/libmmc.o in SPL binary

CONFIG_SPL_SERIAL_SUPPORT
Support for drivers/serial/libserial.o in SPL binary

CONFIG_SPL_SPI_FLASH_SUPPORT
Support for drivers/mtd/spi/libspi_flash.o in SPL binary

CONFIG_SPL_SPI_SUPPORT
Support for drivers/spi/libspi.o in SPL binary

CONFIG_SPL_FAT_SUPPORT
Support for fs/fat/libfat.o in SPL binary

CONFIG_SPL_LIBGENERIC_SUPPORT
Support for lib/libgeneric.o in SPL binary

调制解调器支持:
--------------


[so far only for SMDK2400 boards]


- Modem support enable:

CONFIG_MODEM_SUPPORT


- RTS/CTS Flow control enable:

CONFIG_HWFLOW


- Modem debug support:

CONFIG_MODEM_SUPPORT_DEBUG


Enables debugging stuff (char screen[1024], dbg())

for modem support. Useful only with BDI2000.


- 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().


- General:


In the target system modem support is enabled when a

specific key (key combination) is pressed during

power-on. Otherwise U-Boot will boot normally

(autoboot). The key_pressed() function is called from

board_init(). Currently key_pressed() is a dummy

function, returning 1 and thus enabling modem

initialization.


If there are no modem init strings in the

environment, U-Boot proceed to autoboot; the

previous output (banner, info printfs) will be

suppressed, though.


See also: doc/README.Modem

配置设置:

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


- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;

undefine this when you‘re short of memory.


- CONFIG_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.


- CONFIG_SYS_CBSIZE:Buffer size for input from the Console


- CONFIG_SYS_PBSIZE:Buffer size for Console output


- CONFIG_SYS_MAXARGS:max. Number of arguments accepted for monitor commands


- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to

the application (usually a Linux kernel) when it is

booted


- CONFIG_SYS_BAUDRATE_TABLE:

List of legal baudrate settings for this board.


- CONFIG_SYS_CONSOLE_INFO_QUIET

Suppress display of console information at boot.


- CONFIG_SYS_CONSOLE_IS_IN_ENV

If the board specific function

extern int overwrite_console (void);

returns 1, the stdin, stderr and stdout are switched to the

serial port, else the settings in the environment are used.


- CONFIG_SYS_CONSOLE_OVERWRITE_ROUTINE

Enable the call to overwrite_console().


- CONFIG_SYS_CONSOLE_ENV_OVERWRITE

Enable overwrite of previous console environment settings.


- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:

Begin and End addresses of the area used by the

simple memory test.


- CONFIG_SYS_ALT_MEMTEST:

Enable an alternate, more extensive memory test.


- CONFIG_SYS_MEMTEST_SCRATCH:

Scratch address used by the alternate memory test

You only need to set this if address zero isn‘t writeable


- CONFIG_SYS_MEM_TOP_HIDE (PPC only):

If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,

this specified memory area will get subtracted from the top

(end) of RAM and won‘t get "touched" at all by U-Boot. By

fixing up gd->ram_size the Linux kernel should gets passed

the now "corrected" memory size and won‘t touch it either.

This should work for arch/ppc and arch/powerpc. Only Linux

board ports in arch/powerpc with bootwrapper support that

recalculate the memory size from the SDRAM controller setup

will have to get fixed in Linux additionally.


This option can be used as a workaround for the 440EPx/GRx

CHIP 11 errata where the last 256 bytes in SDRAM shouldn‘t

be touched.


WARNING: Please make sure that this value is a multiple of

the Linux page size (normally 4k). If this is not the case,

then the end address of the Linux memory will be located at a

non page size aligned address and this could cause major

problems.


- CONFIG_SYS_TFTP_LOADADDR:

Default load address for network file downloads


- CONFIG_SYS_LOADS_BAUD_CHANGE:

Enable temporary baudrate change while serial download


- CONFIG_SYS_SDRAM_BASE:

Physical start address of SDRAM. _Must_ be 0 here.


- CONFIG_SYS_MBIO_BASE:

Physical start address of Motherboard I/O (if using a

Cogent motherboard)


- CONFIG_SYS_FLASH_BASE:

Physical start address of Flash memory.


- CONFIG_SYS_MONITOR_BASE:

Physical start address of boot monitor code (set by

make config files to be same as the text base address

(CONFIG_SYS_TEXT_BASE) used when linking) - same as

CONFIG_SYS_FLASH_BASE when booting from flash.


- CONFIG_SYS_MONITOR_LEN:

Size of memory reserved for monitor code, used to

determine _at_compile_time_ (!) if the environment is

embedded within the U-Boot image, or in a separate

flash sector.


- CONFIG_SYS_MALLOC_LEN:

Size of DRAM reserved for malloc() use.


- CONFIG_SYS_BOOTM_LEN:

Normally compressed uImages are limited to an

uncompressed size of 8 MBytes. If this is not enough,

you can define CONFIG_SYS_BOOTM_LEN in your board config file

to adjust this setting to your needs.


- CONFIG_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"

enviroment variable is defined and non-zero. In such case

all data for the Linux kernel must be between "bootm_low"

and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.  The environment

variable "bootm_mapsize" will override the value of

CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,

then the value in "bootm_size" will be used instead.


- CONFIG_SYS_BOOT_RAMDISK_HIGH:

Enable initrd_high functionality.  If defined then the

initrd_high feature is enabled and the bootm ramdisk subcommand

is enabled.


- 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_MAX_FLASH_BANKS:

Max number of Flash memory banks


- CONFIG_SYS_MAX_FLASH_SECT:

Max number of sectors on a Flash chip


- CONFIG_SYS_FLASH_ERASE_TOUT:

Timeout for Flash erase operations (in ms)


- CONFIG_SYS_FLASH_WRITE_TOUT:

Timeout for Flash write operations (in ms)


- CONFIG_SYS_FLASH_LOCK_TOUT

Timeout for Flash set sector lock bit operation (in ms)


- CONFIG_SYS_FLASH_UNLOCK_TOUT

Timeout for Flash clear lock bits operation (in ms)


- CONFIG_SYS_FLASH_PROTECTION

If defined, hardware flash sectors protection is used

instead of U-Boot software protection.


- CONFIG_SYS_DIRECT_FLASH_TFTP:


Enable TFTP transfers directly to flash memory;

without this option such a download has to be

performed in two steps: (1) download to RAM, and (2)

copy from RAM to flash.


The two-step approach is usually more reliable, since

you can check if the download worked before you erase

the flash, but in some situations (when system RAM is

too limited to allow for a temporary copy of the

downloaded image) this option may be very useful.


- 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_FLASH_SPANSION_S29WS_N

s29ws-n MirrorBit flash has non-standard addresses for buffered

write commands.


- CONFIG_SYS_FLASH_QUIET_TEST

If this option is defined, the common CFI flash doesn‘t

print it‘s warning upon not recognized FLASH banks. This

is useful, if some of the configured banks are only

optionally available.


- CONFIG_FLASH_SHOW_PROGRESS

If defined (must be an integer), print out countdown

digits and dots.  Recommended value: 45 (9..1) for 80

column displays, 15 (3..1) for 40 column displays.


- CONFIG_SYS_RX_ETH_BUFFER:

Defines the number of Ethernet receive buffers. On some

Ethernet controllers it is recommended to set this value

to 8 or even higher (EEPRO100 or 405 EMAC), since all

buffers can be full shortly after enabling the interface

on high Ethernet traffic.

Defaults to 4 if not defined.


- CONFIG_ENV_MAX_ENTRIES


Maximum number of entries in the hash table that is used

internally to store the environment settings. The default

setting is supposed to be generous and should work in most

cases. This setting can be used to tune behaviour; see

lib/hashtable.c for details.


The following definitions that deal with the placement and management

of environment data (variable area); in general, we support the

following configurations:


- CONFIG_BUILD_ENVCRC:


Builds up envcrc with the target environment so that external utils

may easily extract it and embed it in final U-Boot images.


- CONFIG_ENV_IS_IN_FLASH:


Define this if the environment is in flash memory.


a) The environment occupies one whole flash sector, which is

   "embedded" in the text segment with the U-Boot code. This

   happens usually with "bottom boot sector" or "top boot

   sector" type flash chips, which have several smaller

   sectors at the start or the end. For instance, such a

   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In

   such a case you would place the environment in one of the

   4 kB sectors - with U-Boot code before and after it. With

   "top boot sector" type flash chips, you would put the

   environment in one of the last sectors, leaving a gap

   between U-Boot and the environment.


- CONFIG_ENV_OFFSET:


   Offset of environment data (variable area) to the

   beginning of flash memory; for instance, with bottom boot

   type flash chips the second sector can be used: the offset

   for this sector is given here.


   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.


- CONFIG_ENV_ADDR:


   This is just another way to specify the start address of

   the flash sector containing the environment (instead of

   CONFIG_ENV_OFFSET).


- CONFIG_ENV_SECT_SIZE:


   Size of the sector containing the environment.



b) Sometimes flash chips have few, equal sized, BIG sectors.

   In such a case you don‘t want to spend a whole sector for

   the environment.


- CONFIG_ENV_SIZE:


   If you use this in combination with CONFIG_ENV_IS_IN_FLASH

   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part

   of this flash sector for the environment. This saves

   memory for the RAM copy of the environment.


   It may also save flash memory if you decide to use this

   when your environment is "embedded" within U-Boot code,

   since then the remainder of the flash sector could be used

   for U-Boot code. It should be pointed out that this is

   STRONGLY DISCOURAGED from a robustness point of view:

   updating the environment in flash makes it always

   necessary to erase the WHOLE sector. If something goes

   wrong before the contents has been restored from a copy in

   RAM, your target system will be dead.


- CONFIG_ENV_ADDR_REDUND

  CONFIG_ENV_SIZE_REDUND


   These settings describe a second storage area used to hold

   a redundant copy of the environment data, so that there is

   a valid backup copy in case there is a power failure during

   a "saveenv" operation.


BE CAREFUL! Any changes to the flash layout, and some changes to the

source code will make it necessary to adapt <board>/u-boot.lds*

accordingly!



- CONFIG_ENV_IS_IN_NVRAM:


Define this if you have some non-volatile memory device

(NVRAM, battery buffered SRAM) which you want to use for the

environment.


- CONFIG_ENV_ADDR:

- CONFIG_ENV_SIZE:


  These two #defines are used to determine the memory area you

  want to use for environment. It is assumed that this memory

  can just be read and written to, without any special

  provision.


BE CAREFUL! The first access to the environment happens quite early

in U-Boot initalization (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.



- CONFIG_ENV_IS_IN_EEPROM:


Use this if you have an EEPROM or similar serial access

device and a driver for it.


- CONFIG_ENV_OFFSET:

- CONFIG_ENV_SIZE:


  These two #defines specify the offset and size of the

  environment area within the total memory of your EEPROM.


- CONFIG_SYS_I2C_EEPROM_ADDR:

  If defined, specified the chip address of the EEPROM device.

  The default address is zero.


- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:

  If defined, the number of bits used to address bytes in a

  single page in the EEPROM device.  A 64 byte page, for example

  would require six bits.


- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:

  If defined, the number of milliseconds to delay between

  page writes.The default is zero milliseconds.


- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:

  The length in bytes of the EEPROM memory array address.  Note

  that this is NOT the chip address length!


- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:

  EEPROM chips that implement "address overflow" are ones

  like Catalyst 24WC04/08/16 which has 9/10/11 bits of

  address and the extra bits end up in the "chip address" bit

  slots. This makes a 24WC08 (1Kbyte) chip look like four 256

  byte chips.


  Note that we consider the length of the address field to

  still be one byte because the extra address bits are hidden

  in the chip address.


- CONFIG_SYS_EEPROM_SIZE:

  The size in bytes of the EEPROM device.


- CONFIG_ENV_EEPROM_IS_ON_I2C

  define this, if you have I2C and SPI activated, and your

  EEPROM, which holds the environment, is on the I2C bus.


- CONFIG_I2C_ENV_EEPROM_BUS

  if you have an Environment on an EEPROM reached over

  I2C muxes, you can define here, how to reach this

  EEPROM. For example:


  #define CONFIG_I2C_ENV_EEPROM_BUS  "pca9547:70:d\0"


  EEPROM which holds the environment, is reached over

  a pca9547 i2c mux with address 0x70, channel 3.


- CONFIG_ENV_IS_IN_DATAFLASH:


Define this if you have a DataFlash memory device which you

want to use for the environment.


- CONFIG_ENV_OFFSET:

- CONFIG_ENV_ADDR:

- CONFIG_ENV_SIZE:


  These three #defines specify the offset and size of the

  environment area within the total memory of your DataFlash placed

  at the specified address.


- CONFIG_ENV_IS_IN_NAND:


Define this if you have a NAND device which you want to use

for the environment.


- CONFIG_ENV_OFFSET:

- CONFIG_ENV_SIZE:


  These two #defines specify the offset and size of the environment

  area within the first NAND device.  CONFIG_ENV_OFFSET must be

  aligned to an erase block boundary.


- CONFIG_ENV_OFFSET_REDUND (optional):


  This setting describes a second storage area of CONFIG_ENV_SIZE

  size used to hold a redundant copy of the environment data, so

  that there is a valid backup copy in case there is a power failure

  during a "saveenv" operation.  CONFIG_ENV_OFFSET_RENDUND must be

  aligned to an erase block boundary.


- CONFIG_ENV_RANGE (optional):


  Specifies the length of the region in which the environment

  can be written.  This should be a multiple of the NAND device‘s

  block size.  Specifying a range with more erase blocks than

  are needed to hold CONFIG_ENV_SIZE allows bad blocks within

  the range to be avoided.


- CONFIG_ENV_OFFSET_OOB (optional):


  Enables support for dynamically retrieving the offset of the

  environment from block zero‘s out-of-band data.  The

  "nand env.oob" command can be used to record this offset.

  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when

  using CONFIG_ENV_OFFSET_OOB.


- 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.


- CONFIG_SYS_SPI_INIT_OFFSET


Defines offset to the initial SPI buffer area in DPRAM. The

area is used at an early stage (ROM part) if the environment

is configured to reside in the SPI EEPROM: We need a 520 byte

scratch DPRAM area. It is used between the two initialization

calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems

to be a good choice since it makes it far enough from the

start of the data area as well as from the stack pointer.


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 getenv_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_ECHO_LINK_DOWN:

Echo the inverted Ethernet link state to the fault LED.


Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR

      also needs to be defined.


- CONFIG_SYS_FAULT_MII_ADDR:

MII address of the PHY to check for the Ethernet link state.


- CONFIG_NS16550_MIN_FUNCTIONS:

Define this if you desire to only have use of the NS16550_init

and NS16550_putc functions for the serial driver located at

drivers/serial/ns16550.c.  This option is useful for saving

space for already greatly restricted images, including but not

limited to NAND_SPL configurations.


Low Level (hardware related) configuration options:

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


- CONFIG_SYS_CACHELINE_SIZE:

Cache Line Size of the CPU.


- CONFIG_SYS_DEFAULT_IMMR:

Default address of the IMMR after system reset.


Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,

and RPXsuper) to be able to adjust the position of

the IMMR register after a reset.


- Floppy Disk Support:

CONFIG_SYS_FDC_DRIVE_NUMBER


the default drive number (default value 0)


CONFIG_SYS_ISA_IO_STRIDE


defines the spacing between FDC chipset registers

(default value 1)


CONFIG_SYS_ISA_IO_OFFSET


defines the offset of register from address. It

depends on which part of the data bus is connected to

the FDC chipset. (default value 0)


If CONFIG_SYS_ISA_IO_STRIDE CONFIG_SYS_ISA_IO_OFFSET and

CONFIG_SYS_FDC_DRIVE_NUMBER are undefined, they take their

default value.


if CONFIG_SYS_FDC_HW_INIT is defined, then the function

fdc_hw_init() is called at the beginning of the FDC

setup. fdc_hw_init() must be provided by the board

source code. It is used to make hardware dependant

initializations.


- CONFIG_IDE_AHB:

Most IDE controllers were designed to be connected with PCI

interface. Only few of them were designed for AHB interface.

When software is doing ATA command and data transfer to

IDE devices through IDE-AHB controller, some additional

registers accessing to these kind of IDE-AHB controller

is requierd.


- CONFIG_SYS_IMMR:Physical address of the Internal Memory.

DO NOT CHANGE unless you know exactly what you‘re

doing! (11-4) [MPC8xx/82xx systems only]


- CONFIG_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 and MPC8260: IMMR (internal memory of the CPU)

- MPC824X: data cache

- PPC4xx:  data cache


- CONFIG_SYS_GBL_DATA_OFFSET:


Offset of the initial data structure in the memory

area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually

CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial

data is located at the end of the available space

(sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -

CONFIG_SYS_INIT_DATA_SIZE), and the initial stack is just

below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +

CONFIG_SYS_GBL_DATA_OFFSET) downward.


Note:

On the MPC824X (or other systems that use the data

cache for initial memory) the address chosen for

CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must

point to an otherwise UNUSED address space between

the top of RAM and the start of the PCI space.


- CONFIG_SYS_SIUMCR:SIU Module Configuration (11-6)


- CONFIG_SYS_SYPCR:System Protection Control (11-9)


- CONFIG_SYS_TBSCR:Time Base Status and Control (11-26)


- CONFIG_SYS_PISCR:Periodic Interrupt Status and Control (11-31)


- CONFIG_SYS_PLPRCR:PLL, Low-Power, and Reset Control Register (15-30)


- CONFIG_SYS_SCCR:System Clock and reset Control Register (15-27)


- CONFIG_SYS_OR_TIMING_SDRAM:

SDRAM timing


- CONFIG_SYS_MAMR_PTA:

periodic timer for refresh


- CONFIG_SYS_DER:Debug Event Register (37-47)


- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,

  CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,

  CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,

  CONFIG_SYS_BR1_PRELIM:

Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)


- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,

  CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,

  CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:

Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)


- CONFIG_SYS_MAMR_PTA, CONFIG_SYS_MPTPR_2BK_4K, CONFIG_SYS_MPTPR_1BK_4K, CONFIG_SYS_MPTPR_2BK_8K,

  CONFIG_SYS_MPTPR_1BK_8K, CONFIG_SYS_MAMR_8COL, CONFIG_SYS_MAMR_9COL:

Machine Mode Register and Memory Periodic Timer

Prescaler definitions (SDRAM timing)


- CONFIG_SYS_I2C_UCODE_PATCH, CONFIG_SYS_I2C_DPMEM_OFFSET [0x1FC0]:

enable I2C microcode relocation patch (MPC8xx);

define relocation offset in DPRAM [DSP2]


- CONFIG_SYS_SMC_UCODE_PATCH, CONFIG_SYS_SMC_DPMEM_OFFSET [0x1FC0]:

enable SMC microcode relocation patch (MPC8xx);

define relocation offset in DPRAM [SMC1]


- CONFIG_SYS_SPI_UCODE_PATCH, CONFIG_SYS_SPI_DPMEM_OFFSET [0x1FC0]:

enable SPI microcode relocation patch (MPC8xx);

define relocation offset in DPRAM [SCC4]


- CONFIG_SYS_USE_OSCCLK:

Use OSCM clock mode on MBX8xx board. Be careful,

wrong setting might damage your board. Read

doc/README.MBX before setting this variable!


- CONFIG_SYS_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)

Offset of the bootmode word in DPRAM used by post

(Power On Self Tests). This definition overrides

#define‘d default value in commproc.h resp.

cpm_8260.h.


- CONFIG_SYS_PCI_SLV_MEM_LOCAL, CONFIG_SYS_PCI_SLV_MEM_BUS, CONFIG_SYS_PICMR0_MASK_ATTRIB,

  CONFIG_SYS_PCI_MSTR0_LOCAL, CONFIG_SYS_PCIMSK0_MASK, CONFIG_SYS_PCI_MSTR1_LOCAL,

  CONFIG_SYS_PCIMSK1_MASK, CONFIG_SYS_PCI_MSTR_MEM_LOCAL, CONFIG_SYS_PCI_MSTR_MEM_BUS,

  CONFIG_SYS_CPU_PCI_MEM_START, CONFIG_SYS_PCI_MSTR_MEM_SIZE, CONFIG_SYS_POCMR0_MASK_ATTRIB,

  CONFIG_SYS_PCI_MSTR_MEMIO_LOCAL, CONFIG_SYS_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,

  CONFIG_SYS_PCI_MSTR_MEMIO_SIZE, CONFIG_SYS_POCMR1_MASK_ATTRIB, CONFIG_SYS_PCI_MSTR_IO_LOCAL,

  CONFIG_SYS_PCI_MSTR_IO_BUS, CONFIG_SYS_CPU_PCI_IO_START, CONFIG_SYS_PCI_MSTR_IO_SIZE,

  CONFIG_SYS_POCMR2_MASK_ATTRIB: (MPC826x only)

Overrides the default PCI memory map in arch/powerpc/cpu/mpc8260/pci.c if set.


- CONFIG_PCI_DISABLE_PCIE:

Disable PCI-Express on systems where it is supported but not

required.


- CONFIG_SYS_SRIO:

Chip has SRIO or not


- CONFIG_SRIO1:

Board has SRIO 1 port available


- CONFIG_SRIO2:

Board has SRIO 2 port available


- CONFIG_SYS_SRIOn_MEM_VIRT:

Virtual Address of SRIO port ‘n‘ memory region


- CONFIG_SYS_SRIOn_MEM_PHYS:

Physical Address of SRIO port ‘n‘ memory region


- CONFIG_SYS_SRIOn_MEM_SIZE:

Size of SRIO port ‘n‘ memory region


- CONFIG_SYS_NDFC_16

Defined to tell the NDFC that the NAND chip is using a

16 bit bus.


- CONFIG_SYS_NDFC_EBC0_CFG

Sets the EBC0_CFG register for the NDFC. If not defined

a default value will be used.


- CONFIG_SPD_EEPROM

Get DDR timing information from an I2C EEPROM. Common

with pluggable memory modules such as SODIMMs


  SPD_EEPROM_ADDRESS

I2C address of the SPD EEPROM


- 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_SYS_DDR_RAW_TIMING

Get DDR timing information from other than SPD. Common with

soldered DDR chips onboard without SPD. DDR raw timing

parameters are extracted from datasheet and hard-coded into

header files or board specific files.


- CONFIG_SYS_83XX_DDR_USES_CS0

Only for 83xx systems. If specified, then DDR should

be configured using CS0 and CS1 instead of CS2 and CS3.


- CONFIG_ETHER_ON_FEC[12]

Define to enable FEC[12] on a 8xx series processor.


- CONFIG_FEC[12]_PHY

Define to the hardcoded PHY address which corresponds

to the given FEC; i. e.

#define CONFIG_FEC1_PHY 4

means that the PHY with address 4 is connected to FEC1


When set to -1, means to probe for first available.


- CONFIG_FEC[12]_PHY_NORXERR

The PHY does not have a RXERR line (RMII only).

(so program the FEC to ignore it).


- 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_MEM).


- CONFIG_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_MEM).


- CONFIG_SKIP_LOWLEVEL_INIT

[ARM, MIPS only] If this variable is defined, then certain

low level initializations (like setting up the memory

controller) are omitted and/or U-Boot does not

relocate itself into RAM.


Normally this variable MUST NOT be defined. The only

exception is when U-Boot is loaded (to RAM) by some

other boot loader or by a debugger which performs

these initializations itself.


- CONFIG_SPL_BUILD

Modifies the behaviour of start.S when compiling a loader

that is executed before the actual U-Boot. E.g. when

compiling a NAND SPL.


- CONFIG_USE_ARCH_MEMCPY

  CONFIG_USE_ARCH_MEMSET

If these options are used a optimized version of memcpy/memset will

be used if available. These functions may be faster under some

conditions but may increase the binary size.

构建软件:
======================

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 http://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

Note: If you wish to generate Windows versions of the utilities in
      the tools directory you can use the MinGW toolchain
      (http://www.mingw.org).  Set your HOST tools to the MinGW
      toolchain and execute ‘make tools‘.  For example:

       $ make HOSTCC=i586-mingw32msvc-gcc HOSTSTRIP=i586-mingw32msvc-strip tools

      Binaries such as tools/mkimage.exe will be created which can
      be executed on computers running Windows.

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_config

where "NAME_config" is the name of one of the existing configu-
rations; see the main Makefile for supported names.

Note: for some board 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_config
- will configure for a plain TQM823L, i. e. no LCD support

      make TQM823L_LCD_config
- 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

By default the build is performed locally and the objects are saved
in the source directory. One of the two methods can be used to change
this behavior and build U-Boot to some external directory:

1. Add O= to the make command line invocations:

make O=/tmp/build distclean
make O=/tmp/build NAME_config
make O=/tmp/build all

2. Set environment variable BUILD_DIR to point to the desired location:

export BUILD_DIR=/tmp/build
make distclean
make NAME_config
make all

Note that the command line "O=" setting overrides the BUILD_DIR environment
variable.


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.  Add a new configuration option for your board to the toplevel
    "Makefile" and to the "MAKEALL" script, using the existing
    entries as examples. Note that here and at many other places
    boards and other names are listed in alphabetical sort order. Please
    keep this order.
2.  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", a "<board>.c", "flash.c" and "u-boot.lds".
3.  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>_config" 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.]
测试U—Boot修改,新硬件的端口,等等。
==============================================================

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 "MAKEALL" script, which will configure and build U-Boot
for ALL supported system. Be warned, this will take a while. You can
select which (cross) compiler to use by passing a `CROSS_COMPILE‘
environment variable to the script, i. e. to use the ELDK cross tools
you can type

CROSS_COMPILE=ppc_8xx- MAKEALL

or to build on a native PowerPC system you can type

CROSS_COMPILE=‘ ‘ MAKEALL

When using the MAKEALL script, the default behaviour is to build
U-Boot in the source directory. This location can be changed by
setting the BUILD_DIR environment variable. Also, for each target
built, the MAKEALL script saves two log files (<target>.ERR and
<target>.MAKEALL) in the <source dir>/LOG directory. This default
location can be changed by setting the MAKEALL_LOGDIR environment
variable. For example:

export BUILD_DIR=/tmp/build
export MAKEALL_LOGDIR=/tmp/log
CROSS_COMPILE=ppc_8xx- MAKEALL

With the above settings build objects are saved in the /tmp/build,
log files are saved in the /tmp/log and the source tree remains clean
during the whole build process.


See also "U-Boot Porting Guide" below.

监控命令-概述:
============================

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

tftpboot- boot image via network using TFTP protocol

       and env variables "ipaddr" and "serverip"

       (and eventually "gatewayip")

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)

md- memory display

mm- memory modify (auto-incrementing)

nm- memory modify (constant address)

mw- memory write (fill)

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

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

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‘


监控命令的详细描述:
========================================

TODO.

For now: just type "help <command>".
环境变量:
======================

U-Boot supports user configuration using Environment Variables which
can be made persistent by saving to Flash memory.

Environment Variables are set using "setenv", printed using
"printenv", and saved to Flash using "saveenv". Using "setenv"
without a value can be used to delete a variable from the
environment. As long as you don‘t save the environment you are
working with an in-memory copy. In case the Flash area containing the
environment is erased by accident, a default environment is provided.

Some configuration options can be set using Environment Variables.

List of environment variables (most likely not complete):

  baudrate- see CONFIG_BAUDRATE

  bootdelay- see CONFIG_BOOTDELAY

  bootcmd- see CONFIG_BOOTCOMMAND

  bootargs- Boot arguments when booting an RTOS image

  bootfile- Name of the image to load with TFTP

  bootm_low- Memory range available for image processing in the bootm
  command can be restricted. This variable is given as
  a hexadecimal number and defines lowest address allowed
  for use by the bootm command. See also "bootm_size"
  environment variable. Address defined by "bootm_low" is
  also the base of the initial memory mapping for the Linux
  kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
  bootm_mapsize.

  bootm_mapsize- Size of the initial memory mapping for the Linux kernel.
  This variable is given as a hexadecimal number and it
  defines the size of the memory region starting at base
  address bootm_low that is accessible by the Linux kernel
  during early boot.  If unset, CONFIG_SYS_BOOTMAPSZ is used
  as the default value if it is defined, and bootm_size is
  used otherwise.

  bootm_size- Memory range available for image processing in the bootm
  command can be restricted. This variable is given as
  a hexadecimal number and defines the size of the region
  allowed for use by the bootm command. See also "bootm_low"
  environment variable.

  updatefile- Location of the software update file on a TFTP server, used
  by the automatic software update feature. Please refer to
  documentation in doc/README.update for more details.

  autoload- if set to "no" (any string beginning with ‘n‘),
  "bootp" will just load perform a lookup of the
  configuration from the BOOTP server, but not try to
  load any image using TFTP

  autostart- if set to "yes", an image loaded using the "bootp",
  "rarpboot", "tftpboot" or "diskboot" commands will
  be automatically started (by internally calling
  "bootm")

  If set to "no", a standalone image passed to the
  "bootm" command will be copied to the load address
  (and eventually uncompressed), but NOT be started.
  This can be used to load and uncompress arbitrary
  data.

  fdt_high- if set this restricts the maximum address that the
  flattened device tree will be copied into upon boot.
  If this is set to the special value 0xFFFFFFFF then
  the fdt will not be copied at all on boot.  For this
  to work it must reside in writable memory, have
  sufficient padding on the end of it for u-boot to
  add the information it needs into it, and the memory
  must be accessible by the kernel.

  i2cfast- (PPC405GP|PPC405EP only)
  if set to ‘y‘ configures Linux I2C driver for fast
  mode (400kHZ). This environment variable is used in
  initialization code. So, for changes to be effective
  it must be saved and board must be reset.

  initrd_high- restrict positioning of initrd images:
  If this variable is not set, initrd images will be
  copied to the highest possible address in RAM; this
  is usually what you want since it allows for
  maximum initrd size. If for some reason you want to
  make sure that the initrd image is loaded below the
  CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
  variable to a value of "no" or "off" or "0".
  Alternatively, you can set it to a maximum upper
  address to use (U-Boot will still check that it
  does not overwrite the U-Boot stack and data).

  For instance, when you have a system with 16 MB
  RAM, and want to reserve 4 MB from use by Linux,
  you can do this by adding "mem=12M" to the value of
  the "bootargs" variable. However, now you must make
  sure that the initrd image is placed in the first
  12 MB as well - this can be done with

  setenv initrd_high 00c00000

  If you set initrd_high to 0xFFFFFFFF, this is an
  indication to U-Boot that all addresses are legal
  for the Linux kernel, including addresses in flash
  memory. In this case U-Boot will NOT COPY the
  ramdisk at all. This may be useful to reduce the
  boot time on your system, but requires that this
  feature is supported by your Linux kernel.

  ipaddr- IP address; needed for tftpboot command

  loadaddr- Default load address for commands like "bootp",
  "rarpboot", "tftpboot", "loadb" or "diskboot"

  loads_echo- see CONFIG_LOADS_ECHO

  serverip- TFTP server IP address; needed for tftpboot command

  bootretry- see CONFIG_BOOT_RETRY_TIME

  bootdelaykey- see CONFIG_AUTOBOOT_DELAY_STR

  bootstopkey- see CONFIG_AUTOBOOT_STOP_STR

  ethprime- When CONFIG_NET_MULTI is enabled controls which
  interface is used first.

  ethact- When CONFIG_NET_MULTI is enabled controls which
  interface is currently active. For example you
  can do the following

  => setenv ethact FEC
  => ping 192.168.0.1 # traffic sent on FEC
  => setenv ethact SCC
  => ping 10.0.0.1 # traffic sent on SCC

  ethrotate- When set to "no" U-Boot does not go through all
  available network interfaces.
  It just stays at the currently selected interface.

  netretry- When set to "no" each network operation will
  either succeed or fail without retrying.
  When set to "once" the network operation will
  fail when all the available network interfaces
  are tried once without success.
  Useful on scripts which control the retry operation
  themselves.

  npe_ucode- set load address for the NPE microcode

  tftpsrcport- If this is set, the value is used for TFTP‘s
  UDP source port.

  tftpdstport- If this is set, the value is used for TFTP‘s UDP
  destination port instead of the Well Know Port 69.

  tftpblocksize - Block size to use for TFTP transfers; if not set,
  we use the TFTP server‘s default block size

  tftptimeout- Retransmission timeout for TFTP packets (in milli-
  seconds, minimum value is 1000 = 1 second). Defines
  when a packet is considered to be lost so it has to
  be retransmitted. The default is 5000 = 5 seconds.
  Lowering this value may make downloads succeed
  faster in networks with high packet loss rates or
  with unreliable TFTP servers.

  vlan- When set to a value < 4095 the traffic over
  Ethernet is encapsulated/received over 802.1q
  VLAN tagged frames.

The following environment variables may be used and automatically
updated by the network boot commands ("bootp" and "rarpboot"),
depending the information provided by your boot server:

  bootfile- see above
  dnsip- IP address of your Domain Name Server
  dnsip2- IP address of your secondary Domain Name Server
  gatewayip- IP address of the Gateway (Router) to use
  hostname- Target hostname
  ipaddr- see above
  netmask- Subnet Mask
  rootpath- Pathname of the root filesystem on the NFS server
  serverip- see above


There are two special Environment Variables:

  serial#- contains hardware identification information such
  as type string and/or serial number
  ethaddr- Ethernet address

These variables can be set only once (usually during manufacturing of
the board). U-Boot refuses to delete or overwrite these variables
once they have been set once.


Further special Environment Variables:

  ver- Contains the U-Boot version string as printed
  with the "version" command. This variable is
  readonly (see CONFIG_VERSION_VARIABLE).


Please note that changes to some configuration parameters may take
only effect after the next boot (yes, that‘s just like Windoze :-).
命令行解析:
=====================

There are two different command line parsers available with U-Boot:
the old "simple" one, and the much more powerful "hush" shell:

Old, simple command line parser:
--------------------------------

- supports environment variables (through setenv / saveenv commands)
- several commands on one line, separated by ‘;‘
- variable substitution using "... ${name} ..." syntax
- special characters (‘$‘, ‘;‘) can be escaped by prefixing with ‘\‘,
  for example:
setenv bootcmd bootm \${address}
- You can also escape text by enclosing in single apostrophes, for example:
setenv addip ‘setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off‘

Hush shell:
-----------

- similar to Bourne shell, with control structures like
  if...then...else...fi, for...do...done; while...do...done,
  until...do...done, ...
- supports environment ("global") variables (through setenv / saveenv
  commands) and local shell variables (through standard shell syntax
  "name=value"); only environment variables can be used with "run"
  command

General rules:
--------------

(1) If a command line (or an environment variable executed by a "run"
    command) contains several commands separated by semicolon, and
    one of these commands fails, then the remaining commands will be
    executed anyway.

(2) If you execute several variables with one call to run (i. e.
    calling run with a list of variables as arguments), any failing
    command will cause "run" to terminate, i. e. the remaining
    variables are not executed.
冗余以太网接口说明:
=======================================

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 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.
镜像格式:
==============

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, LynxOS,
  INTEGRITY).
* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
  IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
  Currently supported: ARM, AVR32, 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支持:
==============
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。
============
对基于Linux的移植U-Boot的系统:
---------------------------------------

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.
配置Linux内核:
-----------------------------
No specific requirements for U-Boot. Make sure you have some root
device (initial ramdisk, NFS) for your target system.
建设一个Linux的镜像:
-----------------------

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_config
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
安装Linux的镜像:
-------------------------

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.
独立的如何:
=================

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
minicom的警告:
================
Over time, many people have reported problems when trying to use the
"minicom" terminal emulation program for serial download. I (wd)
consider minicom to be broken, and recommend not to use it. Under
Unix, I recommend to use C-Kermit for general purpose use (and
especially for kermit binary protocol download ("loadb" command), and
use "cu" for S-Record download ("loads" command).

Nevertheless, if you absolutely want to use it try adding this
configuration to your "File transfer protocols" section:

   Name   Program Name U/D FullScr IO-Red. Multi
X  kermit  /usr/bin/kermit -i -l %l -s Y    U    Y   N   N
Y  kermit  /usr/bin/kermit -i -l %l -r N    D    Y   N   N
NetBSD的注意点:
=============

Starting at version 0.9.2, U-Boot supports NetBSD both as host
(build U-Boot) and target system (boots NetBSD/mpc8xx).

Building requires a cross environment; it is known to work on
NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
need gmake since the Makefiles are not compatible with BSD make).
Note that the cross-powerpc package does not install include files;
attempting to build U-Boot will fail because <machine/ansi.h> is
missing.  This file has to be installed and patched manually:

# cd /usr/pkg/cross/powerpc-netbsd/include
# mkdir powerpc
# ln -s powerpc machine
# cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
# ${EDIT} powerpc/ansi.h## must remove __va_list, _BSD_VA_LIST

Native builds *don‘t* work due to incompatibilities between native
and U-Boot include files.

Booting assumes that (the first part of) the image booted is a
stage-2 loader which in turn loads and then invokes the kernel
proper. Loader sources will eventually appear in the NetBSD source
tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
实施内部:
=========================
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.
初始堆栈,全局数据:
---------------------------

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.

CONFIG_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 implicitely 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 beween 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 Blackfin, the normal C ABI (except for P3) is followed as documented here:
http://docs.blackfin.uclinux.org/doku.php?id=application_binary_interface

    ==> U-Boot will use P3 to hold a pointer to the global data

On ARM, the following registers are used:

R0:function argument word/integer result
R1-R3:function argument word
R9:GOT pointer
R10:stack limit (used only if stack checking if enabled)
R11:argument (frame) pointer
R12:temporary workspace
R13:stack pointer
R14:link register
R15:program counter

    ==> U-Boot will use R8 to hold a pointer to the global data

On Nios II, the ABI is documented here:
http://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.

NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
or current versions of GCC may "optimize" the code too much.
内存管理:
------------------
U-Boot runs in system state and uses physical addresses, i.e. the
MMU is not used either for address mapping nor for memory protection.

The available memory is mapped to fixed addresses using the memory
controller. In this process, a contiguous block is formed for each
memory type (Flash, SDRAM, SRAM), even when it consists of several
physical memory banks.

U-Boot is installed in the first 128 kB of the first Flash bank (on
TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
booting and sizing and initializing DRAM, the code relocates itself
to the upper end of DRAM. Immediately below the U-Boot code some
memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
configuration setting]. Below that, a structure with global Board
Info data is placed, followed by the stack (growing downward).

Additionally, some exception handler code is copied to the low 8 kB
of DRAM (0x00000000 ... 0x00001FFF).

So a typical memory configuration with 16 MB of DRAM could look like
this:

0x0000 0000Exception Vector code
      :
0x0000 1FFF
0x0000 2000Free for Application Use
      :
      :

      :
      :
0x00FB FF20Monitor Stack (Growing downward)
0x00FB FFACBoard Info Data and permanent copy of global data
0x00FC 0000Malloc Arena
      :
0x00FD FFFF
0x00FE 0000RAM Copy of Monitor Code
...eventually: LCD or video framebuffer
...eventually: pRAM (Protected RAM - unchanged by reset)
0x00FF FFFF[End of RAM]
系统初始化:
----------------------

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 onboard 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 MPC8xx or MPC8260), 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.

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.

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.
u-boot的移植指南:
----------------------

[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
list, October 2002]


int main(int argc, char *argv[])
{
sighandler_t no_more_time;

signal(SIGALRM, no_more_time);
alarm(PROJECT_DEADLINE - toSec (3 * WEEK));

if (available_money > available_manpower) {
Pay consultant to port U-Boot;
return 0;
}

Download latest U-Boot source;

Subscribe to u-boot mailing list;

if (clueless)
email("Hi, I am new to U-Boot, how do I get started?");

while (learning) {
Read the README file in the top level directory;
Read http://www.denx.de/twiki/bin/view/DULG/Manual;
Read applicable doc/*.README;
Read the source, Luke;
/* find . -name "*.[chS]" | xargs grep -i <keyword> */
}

if (available_money > toLocalCurrency ($2500))
Buy a BDI3000;
else
Add a lot of aggravation and time;

if (a similar board exists) {/* hopefully... */
cp -a board/<similar> board/<myboard>
cp include/configs/<similar>.h include/configs/<myboard>.h
} else {
Create your own board support subdirectory;
Create your own board include/configs/<myboard>.h file;
}
Edit new board/<myboard> files
Edit new include/configs/<myboard>.h

while (!accepted) {
while (!running) {
do {
Add / modify source code;
} until (compiles);
Debug;
if (clueless)
email("Hi, I am having problems...");
}
Send patch file to the U-Boot email list;
if (reasonable critiques)
Incorporate improvements from email list code review;
else
Defend code as written;
}

return 0;
}

void no_more_time (int sig)
{
      hire_a_guru();
}
编码标准:
-----------------

All contributions to U-Boot should conform to the Linux kernel
coding style; see the file "Documentation/CodingStyle" and the script
"scripts/Lindent" in your Linux kernel source directory.

Source files originating from a different project (for example the
MTD subsystem) are generally exempt from these guidelines and are not
reformated to ease subsequent migration to newer versions of those
sources.

Please note that U-Boot is implemented in C (and to some small parts in
Assembler); no C++ is used, so please do not use C++ style comments (//)
in your code.

Please also stick to the following formatting rules:
- remove any trailing white space
- use TAB characters for indentation and vertical alignment, not spaces
- make sure NOT to use DOS ‘\r\n‘ line feeds
- do not add more than 2 consecutive empty lines to source files
- do not add trailing empty lines to source files

Submissions which do not conform to the standards may be returned
with a request to reformat the changes.
提交补丁:
-------------------

Since the number of patches for U-Boot is growing, we need to
establish some rules. Submissions which do not conform to these rules
may be rejected, even when they contain important and valuable stuff.

Please see http://www.denx.de/wiki/U-Boot/Patches for details.

Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
see http://lists.denx.de/mailman/listinfo/u-boot

When you send a patch, please include the following information with
it:

* For bug fixes: a description of the bug and how your patch fixes
  this bug. Please try to include a way of demonstrating that the
  patch actually fixes something.

* For new features: a description of the feature and your
  implementation.

* A CHANGELOG entry as plaintext (separate from the patch)

* For major contributions, your entry to the CREDITS file

* When you add support for a new board, don‘t forget to add this
  board to the MAINTAINERS file, too.

* If your patch adds new configuration options, don‘t forget to
  document these in the README file.

* The patch itself. If you are using git (which is *strongly*
  recommended) you can easily generate the patch using the
  "git format-patch". If you then use "git send-email" to send it to
  the U-Boot mailing list, you will avoid most of the common problems
  with some other mail clients.

  If you cannot use git, use "diff -purN OLD NEW". If your version of
  diff does not support these options, then get the latest version of
  GNU diff.

  The current directory when running this command shall be the parent
  directory of the U-Boot source tree (i. e. please make sure that
  your patch includes sufficient directory information for the
  affected files).

  We prefer patches as plain text. MIME attachments are discouraged,
  and compressed attachments must not be used.

* If one logical set of modifications affects or creates several
  files, all these changes shall be submitted in a SINGLE patch file.

* Changesets that contain different, unrelated modifications shall be
  submitted as SEPARATE patches, one patch per changeset.


Notes:

* Before sending the patch, run the MAKEALL script on your patched
  source tree and make sure that no errors or warnings are reported
  for any of the boards.

* Keep your modifications to the necessary minimum: A patch
  containing several unrelated changes or arbitrary reformats will be
  returned with a request to re-formatting / split it.

* If you modify existing code, make sure that your new code does not
  add to the memory footprint of the code ;-) Small is beautiful!
  When adding new features, these should compile conditionally only
  (using #ifdef), and the resulting code with the new feature
  disabled must not need more memory than the old code without your
  modification.

* Remember that there is a size limit of 100 kB per message on the
  u-boot mailing list. Bigger patches will be moderated. If they are
  reasonable and not too big, they will be acknowledged. But patches
  bigger than the size limit should be avoided.



















uboot2011.09源代码ReadMe译文

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原文地址:http://blog.csdn.net/waldmer/article/details/45041525

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