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uboot 2013.01 代码简析(1)开发板配置
u-boot下载地址：ftp://ftp.denx.de/pub/u-boot/u-boot-2013.01.01.tar.bz2
下载之后对该文件进行解压。
我试着分析smdk2410_config对应的代码执行流程，接触u-boot时间较短，有不周之处还请见谅。
通常执行u-boot第一步就是进行开发板的配置，而smdk2410的配置命令如下：
make smdk2410_config而Makefile中对应内容如下：
775 %_config:: unconfig 776 @$(MKCONFIG) -A $(@:_config=)
因为Makefile是先执行后面的目标再执行其后的命令，所以会执行unconfig对应的目标：
770 unconfig: 771 @rm -f $(obj)include/config.h $(obj)include/config.mk 772 $(obj)board/*/config.tmp $(obj)board/*/*/config.tmp 773 $(obj)include/autoconf.mk $(obj)include/autoconf.mk.dep
unconfig目标会把以前配置产生的文件先删除掉。
$(MKCONFIG)对应mkconfig文件
当配置参数是smdk2410时，$(@:_config=)的值为smdk2410
所以相当于执行下面的内容：
mkconfig -A smdk2410
mkconfig文件内容如下：
1 #!/bin/sh -e 2 3 # Script to create header files and links to configure 4 # U-Boot for a specific board. 5 # 6 # Parameters: Target Architecture CPU Board [VENDOR] [SOC] 7 # 8 # (C) 2002-2010 DENX Software Engineering, Wolfgang Denk <wd@denx.de> 9 # 10 11 APPEND=no # Default: Create new config file 12 BOARD_NAME="" # Name to print in make output 13 TARGETS="" 14 15 arch="" 16 cpu="" 17 board="" 18 vendor="" 19 soc="" 20 options="" 21 22 if [ \( $# -eq 2 \) -a \( "$1" = "-A" \) ] ; then 23 # Automatic mode 24 line=`egrep -i "^[[:space:]]*${2}[[:space:]]" boards.cfg` || { 25 echo "make: *** No rule to make target \`$2_config‘. Stop." >&2 26 exit 1 27 } 28 29 set ${line} 30 # add default board name if needed 31 [ $# = 3 ] && set ${line} ${1} 32 elif [ "${MAKEFLAGS+set}${MAKELEVEL+set}" = "setset" ] ; then 33 # only warn when using a config target in the Makefile 34 cat <<-EOF 35 36 warning: Please migrate to boards.cfg. Failure to do so will 37 mean removal of your board in the next release. 38 39 EOF 40 sleep 5 41 fi 42 43 while [ $# -gt 0 ] ; do 44 case "$1" in 45 --) shift ; break ;; 46 -a) shift ; APPEND=yes ;; 47 -n) shift ; BOARD_NAME="${1%_config}" ; shift ;; 48 -t) shift ; TARGETS="`echo $1 | sed ‘s:_: :g‘` ${TARGETS}" ; shift ;; 49 *) break ;; 50 esac 51 done 52 53 [ $# -lt 4 ] && exit 1 54 [ $# -gt 7 ] && exit 1 55 56 # Strip all options and/or _config suffixes 57 CONFIG_NAME="${1%_config}" 58 59 [ "${BOARD_NAME}" ] || BOARD_NAME="${1%_config}" 60 61 arch="$2" 62 cpu=`echo $3 | awk ‘BEGIN {FS = ":"} ; {print $1}‘` 63 spl_cpu=`echo $3 | awk ‘BEGIN {FS = ":"} ; {print $2}‘` 64 if [ "$4" = "-" ] ; then 65 board=${BOARD_NAME} 66 else 67 board="$4" 68 fi 69 [ $# -gt 4 ] && [ "$5" != "-" ] && vendor="$5" 70 [ $# -gt 5 ] && [ "$6" != "-" ] && soc="$6" 71 [ $# -gt 6 ] && [ "$7" != "-" ] && { 72 # check if we have a board config name in the options field 73 # the options field mave have a board config name and a list 74 # of options, both separated by a colon (‘:‘); the options are 75 # separated by commas (‘,‘). 76 # 77 # Check for board name 78 tmp="${7%:*}" 79 if [ "$tmp" ] ; then 80 CONFIG_NAME="$tmp" 81 fi 82 # Check if we only have a colon... 83 if [ "${tmp}" != "$7" ] ; then 84 options=${7#*:} 85 TARGETS="`echo ${options} | sed ‘s:,: :g‘` ${TARGETS}" 86 fi 87 } 88 89 if [ "${ARCH}" -a "${ARCH}" != "${arch}" ]; then 90 echo "Failed: \$ARCH=${ARCH}, should be ‘${arch}‘ for ${BOARD_NAME}" 1>&2 91 exit 1 92 fi 93 94 if [ "$options" ] ; then 95 echo "Configuring for ${BOARD_NAME} - Board: ${CONFIG_NAME}, Options: ${options}" 96 else 97 echo "Configuring for ${BOARD_NAME} board..." 98 fi 99 100 # 101 # Create link to architecture specific headers 102 # 103 if [ "$SRCTREE" != "$OBJTREE" ] ; then 104 mkdir -p ${OBJTREE}/include 105 mkdir -p ${OBJTREE}/include2 106 cd ${OBJTREE}/include2 107 rm -f asm 108 ln -s ${SRCTREE}/arch/${arch}/include/asm asm 109 LNPREFIX=${SRCTREE}/arch/${arch}/include/asm/ 110 cd ../include 111 mkdir -p asm 112 else 113 cd ./include 114 rm -f asm 115 ln -s ../arch/${arch}/include/asm asm 116 fi 117 118 rm -f asm/arch 119 120 if [ -z "${soc}" ] ; then 121 ln -s ${LNPREFIX}arch-${cpu} asm/arch 122 else 123 ln -s ${LNPREFIX}arch-${soc} asm/arch 124 fi 125 126 if [ "${arch}" = "arm" ] ; then 127 rm -f asm/proc 128 ln -s ${LNPREFIX}proc-armv asm/proc 129 fi 130 131 # 132 # Create include file for Make 133 # 134 ( echo "ARCH = ${arch}" 135 if [ ! -z "$spl_cpu" ] ; then 136 echo ‘ifeq ($(CONFIG_SPL_BUILD),y)‘ 137 echo "CPU = ${spl_cpu}" 138 echo "else" 139 echo "CPU = ${cpu}" 140 echo "endif" 141 else 142 echo "CPU = ${cpu}" 143 fi 144 echo "BOARD = ${board}" 145 146 [ "${vendor}" ] && echo "VENDOR = ${vendor}" 147 [ "${soc}" ] && echo "SOC = ${soc}" 148 exit 0 ) > config.mk 149 150 # Assign board directory to BOARDIR variable 151 if [ -z "${vendor}" ] ; then 152 BOARDDIR=${board} 153 else 154 BOARDDIR=${vendor}/${board} 155 fi 156 157 # 158 # Create board specific header file 159 # 160 if [ "$APPEND" = "yes" ] # Append to existing config file 161 then 162 echo >> config.h 163 else 164 > config.h # Create new config file 165 fi 166 echo "/* Automatically generated - do not edit */" >>config.h 167 168 for i in ${TARGETS} ; do 169 i="`echo ${i} | sed ‘/=/ {s/=/ /;q; } ; { s/$/ 1/; }‘`" 170 echo "#define CONFIG_${i}" >>config.h ; 171 done 172 173 echo "#define CONFIG_SYS_ARCH \"${arch}\"" >> config.h 174 echo "#define CONFIG_SYS_CPU \"${cpu}\"" >> config.h 175 echo "#define CONFIG_SYS_BOARD \"${board}\"" >> config.h 176 177 [ "${vendor}" ] && echo "#define CONFIG_SYS_VENDOR \"${vendor}\"" >> config.h 178 179 [ "${soc}" ] && echo "#define CONFIG_SYS_SOC \"${soc}\"" >> config.h 180 181 cat << EOF >> config.h 182 #define CONFIG_BOARDDIR board/$BOARDDIR 183 #include <config_cmd_defaults.h> 184 #include <config_defaults.h> 185 #include <configs/${CONFIG_NAME}.h> 186 #include <asm/config.h> 187 #include <config_fallbacks.h> 188 #include <config_uncmd_spl.h> 189 EOF 190 191 exit 0
其中24行从boards.cfg中查找包含smdk2410并其后紧跟空格的行，从而可以得到：
line = smdk2410 arm arm920t - samsung s3c24x0
后续内容就是创建一些文件夹链接。
之后根据line提取出arch,cpu,board,vendor,soc,并写入到include/config.mk中，include/config.mk内容如下：
1 ARCH = arm 2 CPU = arm920t 3 BOARD = smdk2410 4 VENDOR = samsung 5 SOC = s3c24x0
然后将配置写入到include/config.h中，include/config.h内容如下：
1 /* Automatically generated - do not edit */ 2 #define CONFIG_SYS_ARCH "arm" 3 #define CONFIG_SYS_CPU "arm920t" 4 #define CONFIG_SYS_BOARD "smdk2410" 5 #define CONFIG_SYS_VENDOR "samsung" 6 #define CONFIG_SYS_SOC "s3c24x0" 7 #define CONFIG_BOARDDIR board/samsung/smdk2410 8 #include <config_cmd_defaults.h> 9 #include <config_defaults.h> 10 #include <configs/smdk2410.h> 11 #include <asm/config.h> 12 #include <config_fallbacks.h> 13 #include <config_uncmd_spl.h>
这样整个配置部分就基本完成了
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