标签：makefile u-boot samsung arm9
由顶层Makefile文件，梳理U-Boot的编译流程。
小技巧：
在大型Makefile中，很多时候需要确定某个变量的值，一个小方法就是：
$(shell echo "VARIABLE0_VAL = $(VARIABLE0_VAL)" > v_file.txt ) $(shell echo "VARIABLE1_VAL = $(VARIABLE1_VAL)" >> v_file.txt )
1、首先，确定make过程中需要的变量(Makefile的注视符改为/* */)。
VERSION = 2010
PATCHLEVEL = 06
SUBLEVEL =
EXTRAVERSION =
ifneq "$(SUBLEVEL)" ""
U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
else
/* U_BOOT_VERSION = 2010.06 */
U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL)$(EXTRAVERSION)
endif
/* obj变量为空 */
TIMESTAMP_FILE = $(obj)include/timestamp_autogenerated.h
VERSION_FILE = $(obj)include/version_autogenerated.h
/* HOSTARCH：获取主机的硬件架构
* "sed -e"表示后面跟的是命令脚本，"s/xxx/yyy/"表示从打印信息中查找"xxx"然后替换为"yyy"，"."为通配符。
* uname -m获取主机架构信息的命令
* 执行流程：
* uname -m结果为"i686"，符合"s/i.86/i386/"命令脚本，"i686"被替换为"i386"
* 最终结果：HOSTARCH = i386
*/
HOSTARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ -e s/arm.*/arm/ -e s/sa110/arm/ -e s/ppc64/powerpc/ -e s/ppc/powerpc/ -e s/macppc/powerpc/)
/* -s, print the kernel name
* [:upper:], all upper case letters
* [:lower:], all lower case letters
* 执行流程：
* uname -s得到内核名"Linux"，tr把字串的大写转换成小写
* 最终结果：HOSTOS = linux
*/
HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | sed -e 's/\(cygwin\).*/cygwin/')
/* Set shell to bash if possible, otherwise fall back to sh
* 最终结果：SHELL = /bin/bash
*/
SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; else if [ -x /bin/bash ]; then echo /bin/bash; else echo sh; fi; fi)
/* HOSTARCH HOSTOS SHELL 是编译u-boot的主机的信息 */
export HOSTARCH HOSTOS SHELL
/* Deal with colliding definitions from tcsh etc. */
VENDOR=
/* Allow for silent builds */
ifeq (,$(findstring s,$(MAKEFLAGS)))
XECHO = echo
else
XECHO = :
endif
/* U-boot支持在其他目录编译处理目标文件，这样可以保持源代码洁净
* 指定目录的方式有2种：
* 1) 执行make命令时附加"-O dir"项 --'make O=/tmp/build all'
* 2) 设置环境变量BUILD_DIR --'export BUILD_DIR=/tmp/build'; 'make'
*/
ifdef O
/* origin函数的作用是告知某个变量来自与那里，它并不改变变量。
* origin函数有如下几种情况
* 1) 若从未定义过变量O，$(origin O)返回'undefined'
* 2) 若变量O为环境变量，$(origin O)返回'environment'
* 3) 若变量O为默认定义，$(origin O)返回'default'
* 4) 若变量O定义在Makefile中，$(origin O)返回'file'
* 5) 若变量O来自命令行，$(origin O)返回'command line'
* 6) 若变量O被重新定义过，$(origin O)返回'override'
* 7) 若变量O是自动变量，如"$@""$<"等，$(origin O)返回'automatic'
*/
ifeq ("$(origin O)", "command line")
BUILD_DIR := $(O)
endif
endif
/* 若BUILD_DIR不为空，赋值给变量saved-output */
ifneq ($(BUILD_DIR),)
saved-output := $(BUILD_DIR)
/* Attempt to create a output directory.
* -d FILE：FILE exists and is a directory
*/
$(shell [ -d ${BUILD_DIR} ] || mkdir -p ${BUILD_DIR})
/* Verify if it was successful. */
BUILD_DIR := $(shell cd $(BUILD_DIR) && /bin/pwd)
$(if $(BUILD_DIR),,$(error output directory "$(saved-output)" does not exist))
endif # ifneq ($(BUILD_DIR),)
/* CURDIR = .
* OBJTREE = .
* SRCTREE = .
* TOPDIR = .
* LNDIR = .
*/
OBJTREE := $(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))
SRCTREE := $(CURDIR)
TOPDIR := $(SRCTREE)
LNDIR := $(OBJTREE)
export TOPDIR SRCTREE OBJTREE
/* MKCONFIG = ./mkconfig
* mkconfig的分析见上篇：《u-boot的Makefile分析之mkconfig》
* http://blog.csdn.net/u013686019/article/details/42295291
*/
MKCONFIG := $(SRCTREE)/mkconfig
export MKCONFIG
ifneq ($(OBJTREE),$(SRCTREE))
REMOTE_BUILD := 1
export REMOTE_BUILD
endif
/* $(obj) and (src) are defined in config.mk but here in main Makefile
* we also need them before config.mk is included which is the case for
* some targets like unconfig, clean, clobber, distclean, etc.
*/
ifneq ($(OBJTREE),$(SRCTREE))
obj := $(OBJTREE)/
src := $(SRCTREE)/
else
obj :=
src :=
endif
export obj src
/* Make sure CDPATH settings don't interfere */
unexport CDPATH
#########################################################################
/* The "tools" are needed early, so put this first
* Don't include stuff already done in $(LIBS)
*/
SUBDIRS = tools examples/standalone examples/api
/* .PHONY用来标明一个伪目标
* 何为"伪目标"？就是我们定义了一个目标，但这个目标不依赖具体的文件
* "伪目标"有何作用？假设Makefile所在的目录有一个文件，其名字和Makefile中的一个目标相同；由于该文件没有依赖任何文件，所以它一直是最新的，根据make的编译规则，与文件同名的目标将不会被执行
*/
.PHONY : $(SUBDIRS)
ifeq ($(obj)include/config.mk,$(wildcard $(obj)include/config.mk))
/* Include autoconf.mk before config.mk so that the config options are available
* to all top level build files. We need the dummy all: target to prevent the
* dependency target in autoconf.mk.dep from being the default.
*/
all:
sinclude $(obj)include/autoconf.mk.dep
sinclude $(obj)include/autoconf.mk
include $(obj)include/config.mk
/* arm arm920t smdk2410 samsung s3c24x0 */
export ARCH CPU BOARD VENDOR SOC
/* 该ifeq不会被执行，CROSS_COMPILE ?= arm-linux-在文件arch/arm/config.mk中赋值 */
ifeq ($(HOSTARCH),$(ARCH))
CROSS_COMPILE ?=
endif
$(shell echo "HOSTARCH = $(HOSTARCH)" > v_file.txt )
$(shell echo "ARCH = $(ARCH)" >> v_file.txt )
$(shell echo "CROSS_COMPILE= $(CROSS_COMPILE)" >> v_file.txt )
/* load other configuration */
include $(TOPDIR)/config.mk
/* U-Boot objects....order is important (i.e. start must be first) /* OBJS = $(CPUDIR)/start.o
/* addprefix,加前缀函数 * 功能：把前缀加到中的每个单词后面 * 示例：$(addprefix src/,foo bar)返回值是“src/foo src/bar” */ OBJS := $(addprefix $(obj),$(OBJS)) LIBS = lib/libgeneric.a LIBS += lib/lzma/liblzma.a LIBS += lib/lzo/liblzo.a LIBS += $(shell if [ -f board/$(VENDOR)/common/Makefile ]; then echo "board/$(VENDOR)/common/lib$(VENDOR).a"; fi) LIBS += $(CPUDIR)/lib$(CPU).a ifdef SOC LIBS += $(CPUDIR)/$(SOC)/lib$(SOC).a endif LIBS += arch/$(ARCH)/lib/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 fs/yaffs2/libyaffs2.a fs/ubifs/libubifs.a LIBS += net/libnet.a LIBS += disk/libdisk.a LIBS += drivers/bios_emulator/libatibiosemu.a LIBS += drivers/block/libblock.a LIBS += drivers/dma/libdma.a LIBS += drivers/fpga/libfpga.a LIBS += drivers/gpio/libgpio.a LIBS += drivers/hwmon/libhwmon.a LIBS += drivers/i2c/libi2c.a LIBS += drivers/input/libinput.a LIBS += drivers/misc/libmisc.a LIBS += drivers/mmc/libmmc.a LIBS += drivers/mtd/libmtd.a LIBS += drivers/mtd/nand/libnand.a LIBS += drivers/mtd/onenand/libonenand.a LIBS += drivers/mtd/ubi/libubi.a LIBS += drivers/mtd/spi/libspi_flash.a LIBS += drivers/net/libnet.a LIBS += drivers/net/phy/libphy.a LIBS += drivers/pci/libpci.a LIBS += drivers/pcmcia/libpcmcia.a LIBS += drivers/power/libpower.a LIBS += drivers/spi/libspi.a LIBS += drivers/rtc/librtc.a LIBS += drivers/serial/libserial.a LIBS += drivers/twserial/libtws.a LIBS += drivers/usb/gadget/libusb_gadget.a LIBS += drivers/usb/host/libusb_host.a LIBS += drivers/usb/musb/libusb_musb.a LIBS += drivers/usb/phy/libusb_phy.a LIBS += drivers/video/libvideo.a LIBS += drivers/watchdog/libwatchdog.a LIBS += common/libcommon.a LIBS += lib/libfdt/libfdt.a LIBS += api/libapi.a LIBS += post/libpost.a LIBS := $(addprefix $(obj),$(LIBS)) .PHONY : $(LIBS) $(TIMESTAMP_FILE) $(VERSION_FILE) /* BOARDDIR = samsung/smdk2410 */ LIBBOARD = board/$(BOARDDIR)/lib$(BOARD).a LIBBOARD := $(addprefix $(obj),$(LIBBOARD))
$(OBJS): depend
$(MAKE) -C $(CPUDIR) $(if $(REMOTE_BUILD),$@,$(notdir $@))
$(LIBS): depend $(SUBDIRS)
$(MAKE) -C $(dir $(subst $(obj),,$@))
$(LIBBOARD): depend $(LIBS)
$(MAKE) -C $(dir $(subst $(obj),,$@))
$(SUBDIRS): depend
$(MAKE) -C $@ all
$(LDSCRIPT): depend
$(MAKE) -C $(dir $@) $(notdir $@)
$(obj)u-boot.lds: $(LDSCRIPT)
$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - <$^ >$@
$(NAND_SPL): $(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
$(MAKE) -C nand_spl/board/$(BOARDDIR) all
$(U_BOOT_NAND): $(NAND_SPL) $(obj)u-boot.bin
cat $(obj)nand_spl/u-boot-spl-16k.bin $(obj)u-boot.bin > $(obj)u-boot-nand.bin
$(ONENAND_IPL): $(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
$(MAKE) -C onenand_ipl/board/$(BOARDDIR) all
$(U_BOOT_ONENAND): $(ONENAND_IPL) $(obj)u-boot.bin
cat $(ONENAND_BIN) $(obj)u-boot.bin > $(obj)u-boot-onenand.bin
$(VERSION_FILE):
@( printf '#define U_BOOT_VERSION "U-Boot %s%s"\n' "$(U_BOOT_VERSION)" '$(shell $(TOPDIR)/tools/setlocalversion $(TOPDIR))' ) > $@.tmp
@cmp -s $@ $@.tmp && rm -f $@.tmp || mv -f $@.tmp $@
$(TIMESTAMP_FILE):
@LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"' > $@
@LC_ALL=C date +'#define U_BOOT_TIME "%T"' >> $@
gdbtools:
$(MAKE) -C tools/gdb all || exit 1
updater:
$(MAKE) -C tools/updater all || exit 1
env:
$(MAKE) -C tools/env all MTD_VERSION=${MTD_VERSION} || exit 1
# Explicitly make _depend in subdirs containing multiple targets to prevent
# parallel sub-makes creating .depend files simultaneously.
depend dep: $(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
for dir in $(SUBDIRS) $(CPUDIR) $(dir $(LDSCRIPT)) ; do $(MAKE) -C $$dir _depend ; done
TAG_SUBDIRS = $(SUBDIRS)
TAG_SUBDIRS += $(dir $(__LIBS))
TAG_SUBDIRS += include
tags ctags:
ctags -w -o $(obj)ctags `find $(TAG_SUBDIRS) -name '*.[chS]' -print`
etags:
etags -a -o $(obj)etags `find $(TAG_SUBDIRS) -name '*.[chS]' -print`
cscope:
find $(TAG_SUBDIRS) -name '*.[chS]' -print > cscope.files
cscope -b -q -k
SYSTEM_MAP = $(NM) $1 | grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | LC_ALL=C sort
$(obj)System.map: $(obj)u-boot
@$(call SYSTEM_MAP,$<) > $(obj)System.map
#
# Auto-generate the autoconf.mk file (which is included by all makefiles)
#
# This target actually generates 2 files; autoconf.mk and autoconf.mk.dep.
# the dep file is only include in this top level makefile to determine when
# to regenerate the autoconf.mk file.
$(obj)include/autoconf.mk.dep: $(obj)include/config.h include/common.h
@$(XECHO) Generating $@ ; set -e ; : Generate the dependancies ; $(CC) -x c -DDO_DEPS_ONLY -M $(HOSTCFLAGS) $(CPPFLAGS) -MQ $(obj)include/autoconf.mk include/common.h > $@
$(obj)include/autoconf.mk: $(obj)include/config.h
@$(XECHO) Generating $@ ; set -e ; : Extract the config macros ; $(CPP) $(CFLAGS) -DDO_DEPS_ONLY -dM include/common.h | sed -n -f tools/scripts/define2mk.sed > $@.tmp && mv $@.tmp $@
#########################################################################
else # !config.mk
all $(obj)u-boot.hex $(obj)u-boot.srec $(obj)u-boot.bin $(obj)u-boot.img $(obj)u-boot.dis $(obj)u-boot $(filter-out tools,$(SUBDIRS)) $(TIMESTAMP_FILE) $(VERSION_FILE) gdbtools updater env depend dep tags ctags etags cscope $(obj)System.map:
@echo "System not configured - see README" >&2
@ exit 1
tools:
$(MAKE) -C tools
tools-all:
$(MAKE) -C tools HOST_TOOLS_ALL=y
endif # config.mk
.PHONY : CHANGELOG
CHANGELOG:
git log --no-merges U-Boot-1_1_5.. | unexpand -a | sed -e 's/\s\s*$$//' > $@
include/license.h: tools/bin2header COPYING
cat COPYING | gzip -9 -c | ./tools/bin2header license_gzip > include/license.h
#########################################################################
unconfig:
@rm -f $(obj)include/config.h $(obj)include/config.mk $(obj)board/*/config.tmp $(obj)board/*/*/config.tmp $(obj)include/autoconf.mk $(obj)include/autoconf.mk.dep
%: %_config
$(MAKE)
#########################################################################
smdk2410_config : unconfig
@$(MKCONFIG) $(@:_config=) arm arm920t smdk2410 samsung s3c24x0
5、并根据需要转换成其他格式的可执行文件，如二进制格式、S_Record格式等：
/* Add GCC lib */
ifdef USE_PRIVATE_LIBGCC
ifeq ("$(USE_PRIVATE_LIBGCC)", "yes")
PLATFORM_LIBGCC = -L $(OBJTREE)/arch/$(ARCH)/lib -lgcc
else
PLATFORM_LIBGCC = -L $(USE_PRIVATE_LIBGCC) -lgcc
endif
else
PLATFORM_LIBGCC = -L $(shell dirname `$(CC) $(CFLAGS) -print-libgcc-file-name`) -lgcc
endif
PLATFORM_LIBS += $(PLATFORM_LIBGCC)
export PLATFORM_LIBS
/* Special flags for CPP when processing the linker script.
* Pass the version down so we can handle backwards compatibility
* on the fly.
*/
LDPPFLAGS += -include $(TOPDIR)/include/u-boot/u-boot.lds.h $(shell $(LD) --version | sed -ne 's/GNU ld version \([0-9][0-9]*\)\.\([0-9][0-9]*\).*/-DLD_MAJOR=\1 -DLD_MINOR=\2/p')
ifeq ($(CONFIG_NAND_U_BOOT),y)
NAND_SPL = nand_spl
U_BOOT_NAND = $(obj)u-boot-nand.bin
endif
/* subst函数：
* $(subst from, to, text)，在文本"text"中用"to"代替每一处的"from"
*/
__OBJS := $(subst $(obj),,$(OBJS))
__LIBS := $(subst $(obj),,$(LIBS)) $(subst $(obj),,$(LIBBOARD))
#########################################################################
/* Always append ALL so that arch config.mk's can add custom ones */
ALL += $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map $(U_BOOT_NAND) $(U_BOOT_ONENAND)
all: $(ALL)
/* 在顶层的config.mk
* AS = $(CROSS_COMPILE)as
* LD = $(CROSS_COMPILE)ld
* CC = $(CROSS_COMPILE)gcc
* CPP = $(CC) -E
* AR = $(CROSS_COMPILE)ar
* NM = $(CROSS_COMPILE)nm
* LDR = $(CROSS_COMPILE)ldr
* STRIP = $(CROSS_COMPILE)strip
* OBJCOPY = $(CROSS_COMPILE)objcopy
* OBJDUMP = $(CROSS_COMPILE)objdump
* RANLIB = $(CROSS_COMPILE)RANLIB
*/
/* 根据生成的u-boot转换成其他格式的可执行文件 */
$(obj)u-boot.hex: $(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O ihex $< $@
$(obj)u-boot.srec: $(obj)u-boot
$(OBJCOPY) -O srec $< $@
$(obj)u-boot.bin: $(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@
$(obj)u-boot.ldr: $(obj)u-boot
$(CREATE_LDR_ENV)
$(LDR) -T $(CONFIG_BFIN_CPU) -c $@ $< $(LDR_FLAGS)
$(obj)u-boot.ldr.hex: $(obj)u-boot.ldr
$(OBJCOPY) ${OBJCFLAGS} -O ihex $< $@ -I binary
$(obj)u-boot.ldr.srec: $(obj)u-boot.ldr
$(OBJCOPY) ${OBJCFLAGS} -O srec $< $@ -I binary
$(obj)u-boot.img: $(obj)u-boot.bin
$(obj)tools/mkimage -A $(ARCH) -T firmware -C none -a $(TEXT_BASE) -e 0 -n $(shell sed -n -e 's/.*U_BOOT_VERSION//p' $(VERSION_FILE) | sed -e 's/"[ ]*$$/ for $(BOARD) board"/') -d $< $@
$(obj)u-boot.imx: $(obj)u-boot.bin
$(obj)tools/mkimage -n $(IMX_CONFIG) -T imximage -e $(TEXT_BASE) -d $< $@
$(obj)u-boot.kwb: $(obj)u-boot.bin
$(obj)tools/mkimage -n $(KWD_CONFIG) -T kwbimage -a $(TEXT_BASE) -e $(TEXT_BASE) -d $< $@
$(obj)u-boot.sha1: $(obj)u-boot.bin
$(obj)tools/ubsha1 $(obj)u-boot.bin
$(obj)u-boot.dis: $(obj)u-boot
$(OBJDUMP) -d $< > $@
GEN_UBOOT = UNDEF_SYM=`$(OBJDUMP) -x $(LIBBOARD) $(LIBS) | sed -n -e 's/.*\($(SYM_PREFIX)__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`; cd $(LNDIR) && $(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS) --start-group $(__LIBS) --end-group $(PLATFORM_LIBS) -Map u-boot.map -o u-boot
$(obj)u-boot: depend $(SUBDIRS) $(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
$(GEN_UBOOT)
ifeq ($(CONFIG_KALLSYMS),y)
smap=`$(call SYSTEM_MAP,u-boot) | awk '$$2 ~ /[tTwW]/ {printf $$1 $$3 "\\\\000"}'` ; $(CC) $(CFLAGS) -DSYSTEM_MAP="\"$${smap}\"" -c common/system_map.c -o $(obj)common/system_map.o
$(GEN_UBOOT) $(obj)common/system_map.o
endif
标签：makefile u-boot samsung arm9
原文地址：http://blog.csdn.net/u013686019/article/details/42365657
