jz2440:　　 韦东山Linux视频第1期_裸板_UBoot_文件系统_驱动初步第09课第2节 u-boot分析之Makefile结构分析.WMV 《嵌入式linux完全开发手册》 15.2 U-Boot 分析与移植  1. uboot make编译过程： cd u-boot-1.1.6 patch -p1 < ../u-boot-1.1.6_jz2440.patch make 100ask24x0_config make all 2. 分析make 100ask24x0_config     { Makefile mkconfig include/asm include/asm/arch include/asm/proc include/config.mk include/config.h include/configs/100ask24x0.h } vi Makefile ｛ 1886 100ask24x0_config : unconfig 1887 @$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0 ｝ --> mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0 vi mkconfig { # Parameters: Target Architecture CPU Board [VENDOR] [SOC] 确定开发板名称： ｛ 23 [ "${BOARD_NAME}" ] || BOARD_NAME="$1" ｝ 创建到平台/开发板相关的头文件的链接 ｛ 46 cd ./include 47 rm -f asm 48 ln -s asm-$2 asm 51 rm -f asm-$2/arch 56 ln -s ${LNPREFIX}arch-$6 asm-$2/arch 60 rm -f asm-$2/proc 61 ln -s ${LNPREFIX}proc-armv asm-$2/proc ｝ 为Make创建包含文件include/config.mk ｛ 67 echo "ARCH = $2" > config.mk 68 echo "CPU = $3" >> config.mk 69 echo "BOARD = $4" >> config.mk 71 [ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk 73 [ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk ｝ 创建开发板相关的头文件include/config.h ｛ 85 echo "#include " >>config.h ｝ } 3. uboot的配置文件： include/configs/100ask24x0.h 修改这个配置文件来达到裁剪和设置uboot，类似于kernel的make menuconfig的效果。 主要有3类宏： CONFIG_ 主要用来设置功能、使用文件中的哪一块这样的参数; CFG_ 主要用来设置一些更细节的参数; 另外还有些其他的定义。 原则上是这样的，实际上主要还是看代码。 ｛ 36 #define CONFIG_ARM920T 1 /* This is an ARM920T Core */ 45 #define USE_920T_MMU 1 56 #define MTDIDS_DEFAULT "nand0=nandflash0" 57 #define MTDPARTS_DEFAULT "mtdparts=nandflash0:256k@0(bootloader)," 58 "128k(params)," 59 "2m(kernel)," 60 "-(root)" 152 #define CFG_MEMTEST_START 0x30000000 /* memtest works on */ 153 #define CFG_MEMTEST_END 0x33F00000 /* 63 MB in DRAM */ ｝ 4. 分析make all vi Makefile { 116 # load ARCH, BOARD, and CPU configuration 117 include $(OBJTREE)/include/config.mk 118 export ARCH CPU BOARD VENDOR SOC 127 ifeq ($(ARCH),arm) 128 CROSS_COMPILE = arm-linux- 129 endif 163 # load other configuration 164 include $(TOPDIR)/config.mk 166 ######################################################################### 167 # U-Boot objects....order is important (i.e. start must be first) 168 169 OBJS = cpu/$(CPU)/start.o //cpu/arm920t/start.o是第一个obj文件，先后顺序很重要 199 LIBS += lib_$(ARCH)/lib$(ARCH).a 200 LIBS += fs/cramfs/libcramfs.a fs/fat/libfat.a fs/fdos/libfdos.a fs/jffs2/libjffs2.a 201 fs/reiserfs/libreiserfs.a fs/ext2/libext2fs.a 202 LIBS += net/libnet.a 203 LIBS += disk/libdisk.a 204 LIBS += rtc/librtc.a 205 LIBS += dtt/libdtt.a 206 LIBS += drivers/libdrivers.a 207 LIBS += drivers/nand/libnand.a 208 LIBS += drivers/nand_legacy/libnand_legacy.a 209 LIBS += drivers/usb/libusb.a 210 LIBS += drivers/sk98lin/libsk98lin.a 211 LIBS += common/libcommon.a 239 ALL = $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map $(U_BOOT_NAND) 240 241 all: $(ALL) 242 243 $(obj)u-boot.hex: $(obj)u-boot 244 $(OBJCOPY) ${OBJCFLAGS} -O ihex $< $@ 245 246 $(obj)u-boot.srec: $(obj)u-boot 247 $(OBJCOPY) ${OBJCFLAGS} -O srec $< $@ 248 249 $(obj)u-boot.bin: $(obj)u-boot 250 $(OBJCOPY) ${OBJCFLAGS} -O binary $< $@ 251 252 $(obj)u-boot.img: $(obj)u-boot.bin 253 ./tools/mkimage -A $(ARCH) -T firmware -C none 254 -a $(TEXT_BASE) -e 0 255 -n $(shell sed -n -e 's/.*U_BOOT_VERSION//p' $(VERSION_FILE) | 256 sed -e 's/"[ ]*$$/ for $(BOARD) board"/') 257 -d $< $@ 258 259 $(obj)u-boot.dis: $(obj)u-boot 260 $(OBJDUMP) -d $< > $@ 261 262 $(obj)u-boot: depend version $(SUBDIRS) $(OBJS) $(LIBS) $(LDSCRIPT) 263 UNDEF_SYM=`$(OBJDUMP) -x $(LIBS) |sed -n -e 's/.*(__u_boot_cmd_.*)/-u1/p'|sort|uniq`; 264 cd $(LNDIR) && $(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS) 265 --start-group $(__LIBS) --end-group $(PLATFORM_LIBS) 266 -Map u-boot.map -o u-boot 268 $(OBJS): 269 echo $(OBJS) 270 $(MAKE) -C cpu/$(CPU) $(if $(REMOTE_BUILD),$@,$(notdir $@)) 271 272 $(LIBS): 273 $(MAKE) -C $(dir $(subst $(obj),,$@)) 278 $(SUBDIRS): 279 $(MAKE) -C $@ all } 分析 “ 164 include $(TOPDIR)/config.mk ” 相关文件 { arm_config.mk cpu/arm920t/config.mk cpu/arm920t/s3c24x0/config.mk 没有这个文件，忽略 board/100ask24x0/config.mk //TEXT_BASE = 0x33F80000 } vi config.mk { 77 sinclude $(TOPDIR)/$(ARCH)_config.mk # include architecture dependend rules 78 endif 79 ifdef CPU 80 sinclude $(TOPDIR)/cpu/$(CPU)/config.mk # include CPU specific rules 81 endif 82 ifdef SOC 83 sinclude $(TOPDIR)/cpu/$(CPU)/$(SOC)/config.mk # include SoC specific rules 84 endif 85 ifdef VENDOR 86 BOARDDIR = $(VENDOR)/$(BOARD) 87 else 88 BOARDDIR = $(BOARD) 89 endif 90 ifdef BOARD 91 sinclude $(TOPDIR)/board/$(BOARDDIR)/config.mk # include board specific rules 92 endif 117 # Include the make variables (CC, etc...) 118 # 119 AS = $(CROSS_COMPILE)as 120 LD = $(CROSS_COMPILE)ld 121 CC = $(CROSS_COMPILE)gcc .......... } 继续分析Makefile 从199-211这些位置指定了生成LIBS变量就是平台、libasm、cpu、通用目录等下面的库。 OBJS和LIBS就是uboot的组成，它们再通过268-279这些代码生成。 声称以后，就剩下链接了。这由 262 - 266这些代码完成，其中，LDFLAGS指定了程序的布局和地址。 LDFLAGS += -Bstatic -T $(LDSCRIPT) -Ttext $(TEXT_BASE) $(PLATFORM_LDFLAGS) -T board/100ask24x0/u-boot.lds -Ttext 0x33F80000 5.总结编译流程,对于100ask24x0. (1)先编译cpu/arm920t/start.S (2)对于平台、开发板、公共目录等各自调用他们的Makefile生成相应的库； (3)将1，2两步生成的.o, .a文件按照-T board/100ask24x0/u-boot.lds -Ttext 0x33F80000 的布局链接起来。 (4)将第三步得到的uboot文件转换为二进制格式、s-record等格式。 同时也可以根据需要，得到uboot.dis反汇编文件。arm-linux-objdump -d u-boot > u-boot.dis