Uboot Makefile 分析

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1. make smdk2410_config 执行过程

Makefile 目标内容：

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

替换后

 smdk2410_config    :   unconfig    mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

1. 执行 unconfig 依赖 

unconfig:    @rm -f include/config.h include/config.mk \        board/*/config.tmp board/*/*/config.tmp

删除生成的文件，如： config.h, config.mk config.tmp2. 执行脚本，生成头文件和链接配置

    Parameters:  Target  Architecture  CPU  Board [VENDOR] [SOC]    mkconfig smdk2410 arm arm920t smdk2410 NULL s3c24x0

将 mkconfig 脚本精简后，如下：```#!/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]BOARD_NAME="$1"echo "Configuring for ${BOARD_NAME} board..."## Create link to architecture specific headers#cd ./includerm -f asmln -s asm-$2 asmrm -f asm-$2/archln -s arch-$6 asm-$2/archrm -f asm-$2/procln -s proc-armv asm-$2/proc## Create include file for Make#echo "ARCH   = $2" >  config.mkecho "CPU    = $3" >> config.mkecho "BOARD  = $4" >> config.mkecho "SOC    = $6" >> config.mk## Create board specific header file#> config.h      # Create new config fileecho "/* Automatically generated - do not edit */" >>config.hecho "#include <configs/$1.h>" >>config.hexit 0``` mkconfig 脚本效果：    1. 在include目录下成链接文件         asm -> asm-arm        asm-arm/arch -> arch-s3c24x0        asm-arm/proc -> proc-armv    2. 在 include 目录下生成 config.mk 和 config.h 文件        config.mk        ```        ARCH   = arm        CPU    = arm920t        BOARD  = smdk2410        SOC    = s3c24x0        ```        config.h        ```        #include <configs/smdk2410.h>        ```

2. make 编译过程

make 默认目标为 all ```all:    u-boot.srec u-boot.bin System.map   ```all 目标依赖于 u-boot.srec, u-boot.bin, System.map1. 目标：u-boot.srec     ```        u-boot.srec:    u-boot                $(OBJCOPY) ${OBJCFLAGS} -O srec $< $@         ```    依赖于 u-boot     1. 目标 u-boot    ```        u-boot:     depend version $(SUBDIRS) $(OBJS) $(LIBS) $(LDSCRIPT)                UNDEF_SYM=`$(OBJDUMP) -x $(LIBS) |sed  -n -e 's/.*\(__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\                cd $(LNDIR) && $(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS) \                    --start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \                    -Map u-boot.map -o u-boot    ```    依赖于 depend version $(SUBDIRS) $(OBJS) $(LIBS) $(LDSCRIPT)        1. 目标 depend             在 tools examples post post/cpu 目录下生成文件 .depend ，包含了各个目标的依赖        2. 目标 version             生成 include/version_autogenerated.h ,包含为 版本号         3. 目标 $(SUBDIRS)             SUBDIRS = tools examples post post/cpu            进入各个目录执行make all        4. 目标 $(OBJS)             OBJS  = cpu/$(CPU)/start.o            uboot 启动代码         5. 目标 $(LIBS)            LIBS  = lib_generic/libgeneric.a            LIBS += board/$(BOARDDIR)/lib$(BOARD).a            LIBS += cpu/$(CPU)/lib$(CPU).a            LIBS += cpu/$(CPU)/$(SOC)/lib$(SOC).a            LIBS += lib_$(ARCH)/lib$(ARCH).a            LIBS += fs/cramfs/libcramfs.a fs/fat/libfat.a fs/fdos/libfdos.a fs/jffs2/libjffs2.a \                fs/reiserfs/libreiserfs.a fs/ext2/libext2fs.a            LIBS += net/libnet.a            LIBS += disk/libdisk.a            LIBS += rtc/librtc.a            LIBS += dtt/libdtt.a            LIBS += drivers/libdrivers.a            LIBS += drivers/nand/libnand.a            LIBS += drivers/nand_legacy/libnand_legacy.a            LIBS += drivers/sk98lin/libsk98lin.a            LIBS += post/libpost.a post/cpu/libcpu.a            LIBS += common/libcommon.a            编译依赖的库         6. 目标 $(LDSCRIPT) 2. 目标: u-boot.bin    u-boot.bin: $(obj)u-boot        $(OBJCOPY) ${OBJCFLAGS} -O binary $< $@3. 目标： System.map     System.map: $(obj)u-boot        @$(NM) $< | \        grep -v '\(compiled\)|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)|\(LASH[RL]DI\)' | \        sort > $(obj)System.map