u-boot-2012.10分析一配置过程

难得五一没啥安排，闲的无聊，开始移植u-boot-2012.10，与大家分享哈。首先分析u-boot-2012.10，看它与以前的u-boot-1.1.6有啥不同，分析u-boot建Source Insight工程不再详述。这里以TQ2440为例，配置过程分析，从Makefile开始。

一·、分析u-boot根目录下的Makefile

往往在编译u-boot之前，会配置相应单板。eg:make smdk2410_config,打开Makefile，找不到smdk2410_config，只看到746：smdk6400_config。

change@change:~$ cd Si/TQ2440/u-boot-2012.10/

change@change:~/Si/TQ2440/u-boot-2012.10$ ls

api boards.cfg COPYING doc examples lib Makefile net rules.mk test

arch common CREDITS drivers fs MAINTAINERS mkconfig post snapshot.commit tools

board config.mk disk dts include MAKEALL nand_spl README spl

change@change:~/Si/TQ2440/u-boot-2012.10$ grep "smdk2410" * -nR

arch/arm/include/asm/mach-types.h:1646:# define machine_is_smdk2410() (machine_arch_type == MACH_TYPE_SMDK2410)

arch/arm/include/asm/mach-types.h:1648:# define machine_is_smdk2410() (0)

board/samsung/smdk2410/Makefile:28:COBJS := smdk2410.o

boards.cfg:72:smdk2410 arm arm920t - samsung s3c24x0

MAINTAINERS:771: smdk2410 ARM920T

找到了，在根目录下的board.cfg,还是回到Makefile找boards.cfg:718

sinclude $(obj).boards.depend

$(obj).boards.depend: boards.cfg

@awk '(NF && $$1 !~ /^#/) { print $$1 ": " $$1 "_config; $$(MAKE)" }' $< > $@

.boards.depend是个隐藏文件，在根目录下ctrl + h,配置之前没有，配置后就生成了.boards.depend30：smdk:smdk2410_config;$(MAKE)。这里应该是读取根目录下的boards.cfg,生成单板相关依赖文件.boards.depend。

根据这些线索开始分析：

change@change:~/Si/TQ2440/u-boot-2012.10$ make smdk2410_config

Configuring for smdk2410 board...

/Makefile:715

%_config:: unconfig

@$(MKCONFIG) -A $(@:_config=)

%_config:: unconfig，其中%是通配符，会执行MKCONFIG。在Makefile113:MKCONFIG:= $(SRCTREE)/mkconfig,及执行根目录下的mkconfig。 $(:_config=)等于空相当于没有， make smdk2410_config 相当于执行mkconfig -A smdk2410,即开始执行根目录下的mkconfig

二、分析u-boot根目录下的mkconfig

mkconfig -A smdk2410 //$1=-A$2=smdk2410

if [ \( $# -eq 2 \) -a \( "$1" = "-A" \) ] ; then//满足条件

line=`egrep -i "^[[:space:]]*${2}[[:space:]]" boards.cfg`//在boards.cfg中grep smdk2410,知道boards.cfg确实有单板smdk2410,下面echo不会执行

echo "make: *** No rule to make target \`$2_config'. Stop." >&2

set ${line} //在这里设定参数，可以做个试验在这加几个打印语句echo $1;echo $2;echo $3;echo $4;echo $5;echo $6

change@change:~/Si/TQ2440/u-boot-2012.10$ make smdk2410_config

smdk2410

arm

arm920t

-

samsung

s3c24x0

Configuring for smdk2410 board...

OK现在参数明确了$1=smdk2410,$2=arm,$3=arm920t,$4=NULL,$5=samsung,$6=s3c24x0,接着分析配置，就跟以前的u-boot差不多了，我直接把执行的语句列出

CONFIG_NAME="${1%_config}" //CONFIG_NAME=smdk2410_config

arch="$2" //arch=arm

cpu=`echo $3...‘ //cpu=arm920t

if [ "$4" = "-" ] ; then

board=${BOARD_NAME}//board=smdk2410

[ $# -gt 5 ] && [ "$6" != "-" ] && soc="$6"
//soc=s3c24x0

echo "Configuring for ${BOARD_NAME} board..."
//对于配置输出的Configuring for smdk2410 board...

# Create link to architecture specific headers

cd ./include

rm -f asm

ln -s ../arch/${arch}/include/asm asm

rm -f asm/arch

ln -s ${LNPREFIX}arch-${cpu} asm/arch

if [ "${arch}" = "arm" ] ; then

rm -f asm/proc

ln -s ${LNPREFIX}proc-armv asm/proc

# Create include file for Make

( echo "ARCH = ${arch}"

if [ ! -z "$spl_cpu" ] ; then

echo 'ifeq ($(CONFIG_SPL_BUILD),y)'

echo "CPU = ${spl_cpu}"

echo "else"

echo "CPU = ${cpu}"

echo "endif"

else

echo "CPU = ${cpu}" //CPU=arm920t

fi

echo "BOARD = ${board}"

[ "${vendor}" ] && echo "VENDOR = ${vendor}"

[ "${soc}" ] && echo "SOC = ${soc}"

exit 0 ) > config.mk //将上面信息创建到/include/config.mk,可以看到如下：

change@change:~/Si/TQ2440/u-boot-2012.10/include$ cat config.mk

ARCH = arm

CPU = arm920t

BOARD = smdk2410

VENDOR = samsung

SOC = s3c24x0

# Create board specific header file

if [ "$APPEND" = "yes" ] # Append to existing config file

then

echo >> config.h

else

> config.h
# Create new config file //APPEND" = no,创建/include/config.h

fi

echo "/* Automatically generated - do not edit */" >>config.h//加内容到config.h

for i in ${TARGETS} ; do //TARGETS=“”，不执行

i="`echo ${i} | sed '/=/ {s/=//;q; } ; { s/$/1/; }'`"

echo "#define CONFIG_${i}" >>config.h ;

done

echo "#define CONFIG_SYS_ARCH \"${arch}\"" >> config.h //加内容到config.h：#define CONFIG_SYS_ARCH "arm"下面也是如此

echo "#define CONFIG_SYS_CPU \"${cpu}\"" >> config.h//#define CONFIG_SYS_CPU "arm920t"

echo "#define CONFIG_SYS_BOARD \"${board}\"" >> config.h//#define CONFIG_SYS_BOARD "smdk2410"

[ "${vendor}" ] && echo "#define CONFIG_SYS_VENDOR \"${vendor}\"" >> config.h//#define CONFIG_SYS_VENDOR "samsung"

[ "${soc}" ] && echo "#define CONFIG_SYS_SOC \"${soc}\"" >> config.h//#define CONFIG_SYS_SOC "s3c24x0"

cat << EOF >> config.h //加以下内容到config.h

#define CONFIG_BOARDDIR board/$BOARDDIR //#define CONFIG_BOARDDIR board/samsung/smdk2410

#include <config_cmd_defaults.h>

#include <config_defaults.h>

#include <configs/${CONFIG_NAME}.h>

#include <asm/config.h>

#include <config_fallbacks.h>

#include <config_uncmd_spl.h>

EOF

exit 0

分析结果：

1.读取boards.cfg,生成单板相关依赖文件.boards.depend

2.mkconfig -A smdk2410，执行根目录下mkconfig,在boards.cfg中搜索单板

3.在/include目录下生成config.mk、config.h,内容如下：

change@change:~/Si/TQ2440/u-boot-2012.10$ cat include/config.mk

ARCH = arm

CPU = arm920t

BOARD = smdk2410

VENDOR = samsung

SOC = s3c24x0

change@change:~/Si/TQ2440/u-boot-2012.10$ cat include/config.h

/* Automatically generated - do not edit */

#define CONFIG_SYS_ARCH "arm"

#define CONFIG_SYS_CPU "arm920t"

#define CONFIG_SYS_BOARD "smdk2410"

#define CONFIG_SYS_VENDOR "samsung"

#define CONFIG_SYS_SOC "s3c24x0"

#define CONFIG_BOARDDIR board/samsung/smdk2410

#include <config_cmd_defaults.h>

#include <config_defaults.h>

#include <configs/smdk2410.h>

#include <asm/config.h>

#include <config_fallbacks.h>

#include <config_uncmd_spl.h>

change@change:~/Si/TQ2440/u-boot-2012.10$

花了不少时间，配置过程总算分析完成。编译过程以后再分析吧，分析这些东东太累了，比移植u-boot还要累。

原作者：http://blog.csdn.net/u010216127/article/details/8869129?reload