GNU make:http://www.gnu.org/software/make/manual/make.html#Rules
为了便于理解把uboot中的Makefile配置部分弄出来便于理解，这里贴出我的Makefile配置部分。我的是FREESCALE的mx6q_sabresd开发板
mx6solo_sabresd_config
mx6solo_sabresd_mfg_config
mx6solo_sabresd_android_config
mx6dl_sabresd_config
mx6dl_sabresd_mfg_config
mx6dl_sabresd_android_1G_config
mx6dl_sabresd_android_2G_config
mx6q_sabresd_config
mx6q_sabresd_android_1G_config
mx6q_sabresd_android_2G_config
mx6q_sabresd_mfg_config
mx6q_sabresd_iram_config : unconfig
@[ -z "$(findstring iram_,$@)" ] ||
{ echo "TEXT_BASE = 0x00907000" >$(obj)board/freescale/mx6q_sabresd/config.tmp ;
echo "... with iram configuration" ;
}
@$(MKCONFIG) $(@:_config=) arm arm_cortexa8 mx6q_sabresd freescale mx6//$(@:_config=)在做什么很了解，其实它就是将$@即目标
smdk2410_config的后面的_config替换成空
@@@@@@@@@@@@@@@@@ $1 $2 $3 $4 $5
整个mkconfig的作用如下
(1). BOARD_NAME='mx6q_sabresd'
(2). ln -s asm-arm asm
ln -s arch-mx6 asm-arm/arch
ln -s proc-armv asm-arm/proc
(3). 创建include/config.mk
(4). 创建include/config.h
#!/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 <wd@denx.de>
#
APPEND=no # Default: Create new config file
BOARD_NAME="" # Name to print in make output
while [ $# -gt 0 ] ; do
case "$1" in
--) shift ; break ;;
-a) shift ; APPEND=yes ;;
-n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
*) break ;;
esac
done
[ "${BOARD_NAME}" ] || BOARD_NAME="$1"
[ $# -lt 4 ] && exit 1
[ $# -gt 6 ] && exit 1
echo "Configuring for ${BOARD_NAME} board..."
#
# Create link to architecture specific headers
#创建到平台，开发板相关的头文件的链接
#
if [ "$SRCTREE" != "$OBJTREE" ] ; then
mkdir -p ${OBJTREE}/include //。mkdir的-p选项允许你一次性创建多层次的目录，而不是一次只创建单独的目录。例如，我们要在当前目录创建目录Projects/a/src，使用命令
mkdir -p ${OBJTREE}/include2
cd ${OBJTREE}/include2
rm -f asm
ln -s ${SRCTREE}/include/asm-$2 asm
LNPREFIX="../../include2/asm/"
cd ../include //这条语句决定了下面所以的config.mk 以及config.h都是在/include这个文件夹下定义的
rm -rf asm-$2
rm -f asm
mkdir asm-$2
ln -s asm-$2 asm
else
cd ./include
rm -f asm
ln -s asm-$2 asm
fi
rm -f asm-$2/arch
if [ -z "$6" -o "$6" = "NULL" ] ; then
ln -s ${LNPREFIX}arch-$3 asm-$2/arch
else
ln -s ${LNPREFIX}arch-$6 asm-$2/arch
fi
if [ "$2" = "arm" ] ; then
rm -f asm-$2/proc
ln -s ${LNPREFIX}proc-armv asm-$2/proc
fi
#
# Create include file for Make
#cd ../include //这条语句决定了下面所以的config.mk 以及config.h都是在/include这个文件夹下定义的
#
echo "ARCH = $2" > config.mk
echo "CPU = $3" >> config.mk
echo "BOARD = $4" >> config.mk
[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk //此处的 [此中的内容相当于测试是否为空]
[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk
/********************
***这几句很简单，就是创建config.mk，请注意，之前46行我们就已经在include目录下面了，因此这几行执行完成后，config.mk的内容就应该是下面的样子：
1 ARCH = arm
2 CPU = arm_cortexa8
3 BOARD = mx6q_sabresd
4 VENDOR = freescale
5 SOC = mx6
***********************/
#
# Create board specific header file
#最后就开始创建include/config.h:
#
if [ "$APPEND" = "yes" ] # Append to existing config file
then
echo >> config.h
else
> config.h # Create new config file
fi
echo "/* Automatically generated - do not edit */" >>config.h
echo "#include <configs/$1.h>" >>config.h
echo "#include <asm/config.h>" >>config.h
exit 0
/**********************
在这里我打开config.h给各位看下，我的是针对mx6q_sabresd开发板
1 /* Automatically generated - do not edit */
2 #include <configs/mx6q_sabresd_android_2G.h>
3 #include <asm/config.h>
***********************/