u-boot配置过程分析（ARM）

1.u-boot源码结构

    源码目录下一般包含以下目录：

    (1) 平台相关的或者开发板相关的，比如cpu/、baord/

    (2) 通用的函数，比如common/

    (3)通用的设备驱动，比如drivers/

    (4)u-boot工具、示例程序、文档，比如/tools/、/examples、/doc

2.u-boot生成配置文件过程

    根据顶层readme，如果使用board/板名，必须先执行 make 板名_config，然后执行make all

    在Makefile里面有下面

smdk2410_config:unconfig@$(MKCONFIG) $(@:_config=) arm arm920t smdk2410 NULL s3c24x0

而MKCONFIG如下

OBJTREE:= $(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))SRCTREE:= $(CURDIR)TOPDIR:= $(SRCTREE)LNDIR:= $(OBJTREE)exportTOPDIR SRCTREE OBJTREEMKCONFIG:= $(SRCTREE)/mkconfigexport MKCONFIG

  转换后就是./mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

 下面着重分析这个mkconfig

 (1)确定开发板名称

APPEND=no# Default: Create new config fileBOARD_NAME=""# Name to print in make outputwhile [ $# -gt 0 ] ; docase "$1" in--) shift ; break ;;-a) shift ; APPEND=yes ;;-n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;*)  break ;;esacdone[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

  主要判定有没有后缀符-a、--、-n等，默认没有使用，所以结果为BOARD_NAME = smdk2410

  (2)创建平台/开发板相关的头文件的链接，(包括asm_arm，asm_arm/arch，asm_arm/proc) 如下代码所示

## Create link to architecture specific headers#if [ "$SRCTREE" != "$OBJTREE" ] ; thenmkdir -p ${OBJTREE}/includemkdir -p ${OBJTREE}/include2cd ${OBJTREE}/include2rm -f asmln -s ${SRCTREE}/include/asm-$2 asmLNPREFIX="../../include2/asm/"cd ../includerm -rf asm-$2rm -f asmmkdir asm-$2ln -s asm-$2 asmelsecd ./includerm -f asmln -s asm-$2 asmfirm -f asm-$2/archif [ -z "$6" -o "$6" = "NULL" ] ; thenln -s ${LNPREFIX}arch-$3 asm-$2/archelseln -s ${LNPREFIX}arch-$6 asm-$2/archfiif [ "$2" = "arm" ] ; thenrm -f asm-$2/procln -s ${LNPREFIX}proc-armv asm-$2/procfi

  这里主要是删除之前的链接，然后进行重新链接，主要考虑不同平台下配置不一样

  (3)创建include/config.mk

## Create include file for Make#echo "ARCH   = $2" >  config.mkecho "CPU    = $3" >> config.mkecho "BOARD  = $4" >> config.mk[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC    = $6" >> config.mk

   将ARCH、CPU、BOARD、VENDER、SOC，这里$5=NULL，所以只输出了四项

   如下配置mini2440生成的结果

ARCH   = armCPU    = arm920tBOARD  = mini2440SOC    = s3c24x0

  (4)创建开发板相关的头文件 include/config.h

## Create board specific header file#if [ "$APPEND" = "yes" ]# Append to existing config filethenecho >> config.helse> config.h# Create new config filefiecho "/* Automatically generated - do not edit */" >>config.hecho "#include <configs/$1.h>" >>config.h

这里APPEND=no，请看（1）处

比如mini2440生成的文件为

/* Automatically generated - do not edit */#include <configs/mini2440.h>

 从以上可以知道，移植时候可以在board目录新建一个开发板的目录，如board/mini2440/

 然后会自动生成头文件，上面的include/config.h

 另外还需要做一些配置，主要在include/configs/板名.h，比如smdk2410.h

 包括两类宏的开启可以启用有关的配置

 （1）选项 前缀为CONFIG_ 他们用于选择CPU、SOC、开发板类型、设置系统时钟、选择设备驱动、......

/* * High Level Configuration Options * (easy to change) */#define CONFIG_ARM920T1/* This is an ARM920T Core*/#defineCONFIG_S3C24101/* in a SAMSUNG S3C2410 SoC     */#define CONFIG_SMDK24101/* on a SAMSUNG SMDK2410 Board  *//* input clock of PLL */#define CONFIG_SYS_CLK_FREQ12000000/* the SMDK2410 has 12MHz input clock */#define USE_920T_MMU1#undef CONFIG_USE_IRQ/* we don't need IRQ/FIQ stuff */

  设置命令、波特率、......

/* * Command line configuration. */#include <config_cmd_default.h>#define CONFIG_CMD_CACHE#define CONFIG_CMD_DATE#define CONFIG_CMD_ELF#define CONFIG_BOOTDELAY3/*#define CONFIG_BOOTARGS"root=ramfs devfs=mount console=ttySA0,9600" *//*#define CONFIG_ETHADDR08:00:3e:26:0a:5b */#define CONFIG_NETMASK          255.255.255.0#define CONFIG_IPADDR10.0.0.110#define CONFIG_SERVERIP10.0.0.1/*#define CONFIG_BOOTFILE"elinos-lart" *//*#define CONFIG_BOOTCOMMAND"tftp; bootm" */#if defined(CONFIG_CMD_KGDB)#define CONFIG_KGDB_BAUDRATE115200/* speed to run kgdb serial port *//* what's this ? it's not used anywhere */#define CONFIG_KGDB_SER_INDEX1/* which serial port to use */#endif

注意命令中有个config_cmd_default.h 里面包含了默认的uboot命令，可以在里面增加或者删除，也可以在其下面定义有关命令

下面主要是配置启动，网络参数

(2)参数 前缀为CFG_，用于设置malloc缓冲池的大小、uboot提示符、uboot下载默认加载地址、flash起始地址、......

/* * Size of malloc() pool */#define CFG_MALLOC_LEN(CONFIG_ENV_SIZE + 128*1024)#define CFG_GBL_DATA_SIZE128/* size in bytes reserved for initial data *//* * Hardware drivers */#define CONFIG_DRIVER_CS89001/* we have a CS8900 on-board */#define CS8900_BASE0x19000300#define CS8900_BUS161 /* the Linux driver does accesses as shorts */

命令提示符、字符缓冲区的大小、默认下载地址、.......

/* * Miscellaneous configurable options */#defineCFG_LONGHELP/* undef to save memory*/#defineCFG_PROMPT"SMDK2410 # "/* Monitor Command Prompt*/#defineCFG_CBSIZE256/* Console I/O Buffer Size*/#defineCFG_PBSIZE (CFG_CBSIZE+sizeof(CFG_PROMPT)+16) /* Print Buffer Size */#defineCFG_MAXARGS16/* max number of command args*/#define CFG_BARGSIZECFG_CBSIZE/* Boot Argument Buffer Size*/#define CFG_MEMTEST_START0x30000000/* memtest works on*/#define CFG_MEMTEST_END0x33F00000/* 63 MB in DRAM*/#undef  CFG_CLKS_IN_HZ/* everything, incl board info, in Hz */#defineCFG_LOAD_ADDR0x33000000/* default load address*/

里面还有stack、物理内存映射、Nor Flash设置、BOOTP设置、.......

3.总结开发板配置过程：

 开发板名称->头文件链接->include/config.mk->include/config.h

文档：

#!/bin/sh -e# Script to create header files and links to configure# U-Boot for a specific board.## Parameters:  Target  Architecture  CPU  Board [VENDOR] [SOC]## (C) 2002-2006 DENX Software Engineering, Wolfgang Denk <[e-mail]>##./mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0   $0         $1     $2   $3       $4      $5    $6APPEND=no      # Default: Create new config fileBOARD_NAME=""  # Name to print in make output[ "${BOARD_NAME}" ] || BOARD_NAME="$1"#BOARD_NAME= smdk2410[ $# -lt 4 ] && exit 1[ $# -gt 6 ] && exit 1echo "Configuring for ${BOARD_NAME} board..."## Create link to architecture specific headers#cd ./includerm -f asmln -s asm-$2 asm  # 建立链接文件 ln -s asm-arm asmrm -f asm-$2/arch   # asm-arm/archln -s ${LNPREFIX}arch-$6 asm-$2/arch  # ln -s arch-s3c24x0 asm-arm/archif [ "$2" = "arm" ] ; thenrm -f asm-$2/procln -s ${LNPREFIX}proc-armv asm-$2/proc # ln -s proc-armv asm-arm/procfi## Create include file for Make#echo "ARCH   = $2" >  config.mkecho "CPU    = $3" >> config.mkecho "BOARD  = $4" >> config.mk#ARCH  = arm#CPU   = arm920t#BOARD = smdk2410[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC    = $6" >> config.mk#SOC   = s3c24x0## Create board specific header file#> config.h# Create new config fileecho "/* Automatically generated - do not edit */" >>config.hecho "#include <configs/$1.h>" >>config.h#/* Automatically generated - do not edit */##include <configs/smdk2410.h>exit 0