u-boot2010.03 配置编译目标分析 .

转载自： http://blog.csdn.net/yyttiao/article/details/7899008

 

该系列教程会根据uboot的编译过程进程分析，如何编译，那么将会如何分析这些流程
此处我还没有增加6410的支持，先看6400 的过程，因为还没有到增加的地方，分析完整个流程之后，会写如何移植uboot到s3c6410的。知道了工作的流程，再去移植会事半功倍的。

拿到uboot首先会修改编译的目标：

make smdk6400_config

对执行如下的目标

#########################################################################
## ARM1176 Systems
#########################################################################
smdk6400_noUSB_config   \
smdk6400_config :   unconfig
    @mkdir -p $(obj)include $(obj)board/samsung/smdk6400
    @mkdir -p $(obj)nand_spl/board/samsung/smdk6400
    @echo "#define CONFIG_NAND_U_BOOT" > $(obj)include/config.h
    @if [ -z "$(findstring smdk6400_noUSB_config,$@)" ]; then    \
        echo "RAM_TEXT = 0x57e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
        $(MKCONFIG) $(@:_config=) arm arm1176 smdk6400 samsung s3c64xx;  \
    else     \
        echo "RAM_TEXT = 0xc7e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
        $(MKCONFIG) $(@:_noUSB_config=) arm arm1176 smdk6400 samsung s3c64xx;   \
    fi
    @echo "CONFIG_NAND_U_BOOT = y" >> $(obj)include/config.mk

#########################################################################
## ARM1176 Systems
#########################################################################
smdk6400_noUSB_config	\
smdk6400_config	:	unconfig
    @mkdir -p $(obj)include $(obj)board/samsung/smdk6400
    @mkdir -p $(obj)nand_spl/board/samsung/smdk6400
    @echo "#define CONFIG_NAND_U_BOOT" > $(obj)include/config.h
    @if [ -z "$(findstring smdk6400_noUSB_config,$@)" ]; then	 \
        echo "RAM_TEXT = 0x57e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
        $(MKCONFIG) $(@:_config=) arm arm1176 smdk6400 samsung s3c64xx;	 \
    else	 \
        echo "RAM_TEXT = 0xc7e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
        $(MKCONFIG) $(@:_noUSB_config=) arm arm1176 smdk6400 samsung s3c64xx;	\
    fi
    @echo "CONFIG_NAND_U_BOOT = y" >> $(obj)include/config.mk

这里主要看的是如下2句

echo "RAM_TEXT = 0x57e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
$(MKCONFIG) $(@:_config=) arm arm1176 smdk6400 samsung s3c64xx;  \

echo "RAM_TEXT = 0x57e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\
$(MKCONFIG) $(@:_config=) arm arm1176 smdk6400 samsung s3c64xx;	 \

首先会将 RAM_TEXT = 0x57e00000 写入到 $(obj)board/samsung/smdk6400/config.tmp 这个文件内
$(obj) 是目标的编译生成的路劲或者是当前UBOOT的目录，这就要看你有没有指定编译目录了

重点分析 $(MKCONFIG) $(@:_config=) arm arm1176 smdk6400 samsung s3c64xx; \
会调用 $(MKCONFIG) 而 MKCONFIG := $(SRCTREE)/mkconfig
也就是说最终会变成如下形式
mkconfig smdk6400 arm arm1176 smdk6400 samsung s3c64xx

下面就得进入 mkconfig的代码内进行分析。。记录上面的参数，请大家打开对应的文件，一步步的看着然后分析

#!/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 <[email protected]>
#

#!/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 <[email protected]>
#

这里有一句说明了参数的意思 Parameters: Target Architecture CPU Board [VENDOR] [SOC]
对应我们传递进来的参数看到为：
Parameters:
1:Target = smdk6400
2:Architecture = arm
3:CPU = arm1176
4:Board = smdk6400
5:[VENDOR] = samsung
6:[SOC] = s3c64xx

APPEND=no   # Default: Create new config file
BOARD_NAME=""   # Name to print in make output
TARGETS=""

while [ $# -gt 0 ] ; do
    case "$1" in
        --) shift ; break ;;
        -a) shift ; APPEND=yes ;;
        -n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
        -t) shift ; TARGETS="`echo $1 | sed 's:_: :g'` ${TARGETS}" ; shift ;;
        *) break ;;
    esac
done

APPEND=no	# Default: Create new config file
BOARD_NAME=""	# Name to print in make output
TARGETS=""

while [ $# -gt 0 ] ; do
    case "$1" in
        --) shift ; break ;;
        -a) shift ; APPEND=yes ;;
        -n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
        -t) shift ; TARGETS="`echo $1 | sed 's:_: :g'` ${TARGETS}" ; shift ;;
        *) break ;;
    esac
done

这里显示没有没有特殊的标志，所以就不需要了

[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

[ $# -lt 4 ] && exit 1
[ $# -gt 6 ] && exit 1

if [ "${ARCH}" -a "${ARCH}" != "$2" ]; then
    echo "Failed: \$ARCH=${ARCH}, should be '$2' for ${BOARD_NAME}" 1>&2
    exit 1
fi

echo "Configuring for ${BOARD_NAME} board..."
/*这句就是我们看到的配置信息了*/

[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

[ $# -lt 4 ] && exit 1
[ $# -gt 6 ] && exit 1

if [ "${ARCH}" -a "${ARCH}" != "$2" ]; then
    echo "Failed: \$ARCH=${ARCH}, should be '$2' for ${BOARD_NAME}" 1>&2
    exit 1
fi

echo "Configuring for ${BOARD_NAME} board..."
/*这句就是我们看到的配置信息了*/

下面开始创建针对目标平台的连接目录了。uboot是这么编译的，将选中的平台相关的文件夹，通过软连接的方式，到一个指定的目录
那么编译的时候，就只要去这个统一的指定目录下找，就能针对不同的平台编译了。具体看下下面的建立过程

#
# Create link to architecture specific headers
#
/* 这里表示目标目录跟源码目录不一致，建立相应的目录，由于我没有指定目标目录，所以执行else部分 */
if [ "$SRCTREE" != "$OBJTREE" ] ; then
    mkdir -p ${OBJTREE}/include
    mkdir -p ${OBJTREE}/include2
    cd ${OBJTREE}/include2
    rm -f asm
    ln -s ${SRCTREE}/include/asm-$2 asm
    LNPREFIX="../../include2/asm/"
    cd ../include
    rm -rf asm-$2
    rm -f asm
    mkdir asm-$2
    ln -s asm-$2 asm
else
    cd ./include
    /* 删除asm目录 */
    rm -f asm
    /*
     * 建立asm指向对应的目录，根据我上面标的，$2就是 2:Architecture = arm
     * 所以这里就是 ln -s asm-arm asm
     */
    ln -s asm-$2 asm
fi

/*
* 这里开始建立arch目录，有了上面的asm目录建立，这里就简单多了
* 删除 rm -f asm-arm/arch
*/
rm -f asm-$2/arch

if [ -z "$6" -o "$6" = "NULL" ] ; then
    ln -s ${LNPREFIX}arch-$3 asm-$2/arch
else
    /*
     * ln -s arch-s3c64xx asm-arm/arch
     */
    ln -s ${LNPREFIX}arch-$6 asm-$2/arch
fi

/* 如果是arm平台，需要多建立一个proc目录 */
if [ "$2" = "arm" ] ; then
    rm -f asm-$2/proc
    ln -s ${LNPREFIX}proc-armv asm-$2/proc
fi

#
# Create include file for Make
#
/*
* 这里为make编译的时候创建一些环境变量，写入到config.mk文件
*/
echo "ARCH = $2" > config.mk
echo "CPU = $3" >> config.mk
echo "BOARD = $4" >> config.mk

[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk

# Assign board directory to BOARDIR variable
if [ -z "$5" -o "$5" = "NULL" ] ; then
    BOARDDIR=$4
else
    BOARDDIR=$5/$4
fi

#
# Create board specific header file
#
/*
* 开始创建特殊的头文件，被好多文件加载的
* APPEND = no,于是创建了新的config.h
*/
if [ "$APPEND" = "yes" ]    # Append to existing config file
then
    echo >> config.h
else
    > config.h    # Create new config file
fi

/* 写入如下信息到该新建的头文件内 */
echo "/* Automatically generated - do not edit */" >>config.h

for i in ${TARGETS} ; do
    echo "#define CONFIG_MK_${i} 1" >>config.h ;
done

cat << EOF >> config.h
#define CONFIG_BOARDDIR board/$BOARDDIR
#include <config_defaults.h>
/* 这里需要注意的是，$1 对应的是smdk6400 正好指定了 include/config/smdk6400.h 配置头文件，也就是为什么移植需要该这个头文件，否则找不到的原因 */
#include <configs/$1.h>
#include <asm/config.h>
EOF

exit 0

#
# Create link to architecture specific headers
#
/* 这里表示目标目录跟源码目录不一致，建立相应的目录，由于我没有指定目标目录，所以执行else部分 */
if [ "$SRCTREE" != "$OBJTREE" ] ; then
    mkdir -p ${OBJTREE}/include
    mkdir -p ${OBJTREE}/include2
    cd ${OBJTREE}/include2
    rm -f asm
    ln -s ${SRCTREE}/include/asm-$2 asm
    LNPREFIX="../../include2/asm/"
    cd ../include
    rm -rf asm-$2
    rm -f asm
    mkdir asm-$2
    ln -s asm-$2 asm
else
    cd ./include
    /* 删除asm目录 */
    rm -f asm
    /* 
     * 建立asm指向对应的目录，根据我上面标的，$2就是 2:Architecture = arm 
     * 所以这里就是 ln -s asm-arm asm
     */
    ln -s asm-$2 asm
fi

/*
* 这里开始建立arch目录，有了上面的asm目录建立，这里就简单多了
* 删除 rm -f asm-arm/arch
*/
rm -f asm-$2/arch

if [ -z "$6" -o "$6" = "NULL" ] ; then
    ln -s ${LNPREFIX}arch-$3 asm-$2/arch
else
    /*
     * ln -s arch-s3c64xx asm-arm/arch
     */
    ln -s ${LNPREFIX}arch-$6 asm-$2/arch
fi

/* 如果是arm平台，需要多建立一个proc目录 */
if [ "$2" = "arm" ] ; then
    rm -f asm-$2/proc
    ln -s ${LNPREFIX}proc-armv asm-$2/proc
fi

#
# Create include file for Make
#
/*
* 这里为make编译的时候创建一些环境变量，写入到config.mk文件
*/
echo "ARCH = $2" > config.mk
echo "CPU = $3" >> config.mk
echo "BOARD = $4" >> config.mk

[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk

# Assign board directory to BOARDIR variable
if [ -z "$5" -o "$5" = "NULL" ] ; then
    BOARDDIR=$4
else
    BOARDDIR=$5/$4
fi

#
# Create board specific header file
#
/*
* 开始创建特殊的头文件，被好多文件加载的
* APPEND = no,于是创建了新的config.h
*/
if [ "$APPEND" = "yes" ]	# Append to existing config file
then
    echo >> config.h
else
    > config.h	 # Create new config file
fi

/* 写入如下信息到该新建的头文件内 */
echo "/* Automatically generated - do not edit */" >>config.h

for i in ${TARGETS} ; do
    echo "#define CONFIG_MK_${i} 1" >>config.h ;
done

cat << EOF >> config.h
#define CONFIG_BOARDDIR board/$BOARDDIR
#include <config_defaults.h>
/* 这里需要注意的是，$1 对应的是smdk6400 正好指定了 include/config/smdk6400.h 配置头文件，也就是为什么移植需要该这个头文件，否则找不到的原因 */
#include <configs/$1.h>
#include <asm/config.h>
EOF

exit 0

整个配置过程就结束了。下面进行总结下

1：在Makefile中将RAM_TEXT = 0x57e00000 写入board/samsung/smdk6400/config.tmp 中
   这个地址在最终会变成 TEXT_BASE 可以在board/samsung/smdk6400/config.mk 中看到
   echo "RAM_TEXT = 0x57e00000" >> $(obj)board/samsung/smdk6400/config.tmp;\

2：创建软连接到目标生成的工作目录下，不指定就是在uboot的源码目录下
   ln -s asm-$2 asm
   ln -s ${LNPREFIX}arch-$6 asm-$2/arch
   ln -s ${LNPREFIX}proc-armv asm-$2/proc

3：创建config.mk 为编译指定一些变量
   echo "ARCH = $2" > config.mk
   echo "CPU = $3" >> config.mk
   echo "BOARD = $4" >> config.mk
   [ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk
   [ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk

4：创建头文件，指向配置的头文件 include/config.h
   cat << EOF >> config.h
   #define CONFIG_BOARDDIR board/$BOARDDIR
   #include <config_defaults.h>
   #include <configs/$1.h>
   #include <asm/config.h>
   EOF