u-boot-1.1.6_s3c2440/Makefile 阅读

好不容易把sublime输入中文的问题处理完了。

站在别人的研究基础上，依葫芦画瓢的把阅读u-boot的注释放上来，供大家搜索借鉴。

本文基于u-boot-1.1.6 一边阅读一边根据韦东山老师所写的「嵌入式Linux应用开发」改写。

VERSION = 1

PATCHLEVEL = 1

SUBLEVEL = 6

EXTRAVERSION =

U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)

VERSION_FILE = $(obj)include/version_autogenerated.h

# 确认HOSTARCH

# uname -m : 显示 ARCH Host

# sed -e s/i.86/i386/ : 替换i.86为i386 -e执行但行脚本

HOSTARCH := $(shell uname -m | \
sed -e s/i.86/i386/ \
-e s/sun4u/sparc64/ \
-e s/arm.*/arm/ \
-e s/sa110/arm/ \
-e s/powerpc/ppc/ \
-e s/macppc/ppc/)

# 确认HOSTOS

# uname -s : 显示 kernel

# tr '[:upper:]' '[:lower:]' : 转换大写成为小写

# sed -e 's/\(cygwin\).*/cygwin/'：转换(cygwin).*为cygwin

HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | \
sed -e 's/\(cygwin\).*/cygwin/')

export HOSTARCH HOSTOS

# Deal with colliding definitions from tcsh etc.

VENDOR=

#########################################################################

#U-boot支持两种方法在别的文件夹内创建文件,否则在内置的SRCDIR文件夹内创建文件。

## U-boot build supports producing a object files to the separate external

# directory. Two use cases are supported:

#

# 1) Add O= to the make command line

# 'make O=/tmp/build all'

# origin(O) : 判断O的类型是不是command line

ifdef O

ifeq ("$(origin O)", "command line")

BUILD_DIR := $(O)

endif

endif

#

# 2) Set environement variable BUILD_DIR to point to the desired location

# 'export BUILD_DIR=/tmp/build'

# 'make'

#

# Command line 'O=' setting overrides BUILD_DIR environent variable.

#

# When none of the above methods is used the local build is performed and

# the object files are placed in the source directory.

#

# 判断环境变量BUILD_DIR是否存在

ifneq ($(BUILD_DIR),)

saved-output := $(BUILD_DIR)

# 判断目录是否已经存在，不存在尝试新建

$(shell [ -d ${BUILD_DIR} ] || mkdir -p ${BUILD_DIR})

# 尝试进入该目录判断是否成功

BUILD_DIR := $(shell cd $(BUILD_DIR) && /bin/pwd)

$(if $(BUILD_DIR),,$(error output directory "$(saved-output)" does not exist))

endif # ifneq ($(BUILD_DIR),)

# 如果不是在别的目录新建，即OBJTREE不存在

# OBJTREE，CURDIR，SRCTREE，TOPTREE，LNDIR相同

OBJTREE := $(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))

SRCTREE := $(CURDIR)

TOPDIR := $(SRCTREE)

LNDIR := $(OBJTREE)

export TOPDIR SRCTREE OBJTREE

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

#########################################################################

# 判断用户是否执行过 make <board_name>_config命令。

# 因为执行过会生成/include/config.mk

# $(wildcard PATTERN...) 在定义变量是使通配符有效

# 展开为已经存在的、使用空格分开的、匹配此模式的所有文件列表。

# 如果不存在任何符合此模式的文件，函数会忽略模式字符并返回空

ifeq ($(OBJTREE)/include/config.mk,$(wildcard $(OBJTREE)/include/config.mk))

# 从make <board_name>_configinclude/config.mk读取

# load ARCH, BOARD, and CPU configuration

include $(OBJTREE)/include/config.mk

export ARCH CPU BOARD VENDOR SOC

# 判断CROSS_COMPILE

# 这里是 CROSS_COMPILE = arm-linux-

ifndef CROSS_COMPILE

ifeq ($(ARCH),arm)

CROSS_COMPILE = arm-linux-

endif

endif

export CROSS_COMPILE

# load other configuration

include $(TOPDIR)/config.mk

#########################################################################

# U-Boot objects....order is important (i.e. start must be first)

# cpu/arm920t/start.o 

OBJS  = cpu/$(CPU)/start.o

# $(addprefix PREFIX,NAMES…)

OBJS := $(addprefix $(obj),$(OBJS))

LIBS  = lib_generic/libgeneric.a

# board/100ask24x0/lib/100ask24x0.a

LIBS += board/$(BOARDDIR)/lib$(BOARD).a

# /cpu/arm920t/libarm920t.a

LIBS += cpu/$(CPU)/lib$(CPU).a

# lib_arm/libarm.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

LIBS += $(BOARDLIBS)

LIBS := $(addprefix $(obj),$(LIBS))

.PHONY : $(LIBS)

# Add GCC lib

PLATFORM_LIBS += -L $(shell dirname `$(CC) $(CFLAGS) -print-libgcc-file-name`) -lgcc

# The "tools" are needed early, so put this first

# Don't include stuff already done in $(LIBS)

# 被depend依赖

SUBDIRS = tools \
 examples \
 post \
 post/cpu

.PHONY : $(SUBDIRS)

ifeq ($(CONFIG_NAND_U_BOOT),y)

NAND_SPL = nand_spl

U_BOOT_NAND = $(obj)u-boot-nand.bin

endif

__OBJS := $(subst $(obj),,$(OBJS))

__LIBS := $(subst $(obj),,$(LIBS))

#########################################################################

#########################################################################

#  "make all”命令将生成u-boot.srec，u-boot.bin，System.map 和 u-boot-nand.bin

#  其中u-boot是ELF文件，u-boot.srec是Motorola S-Record format文件

# System.map 是U-Boot的符号表 # u-boot.bin是最终烧写到开发板的二进制可执行的文件。

ALL = $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map $(U_BOOT_NAND)

all: $(ALL)

$(obj)u-boot.hex: $(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O ihex $< $@

$(obj)u-boot.srec: $(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O srec $< $@

# 使用 0xff 填充段与段之间的空隙

#  arm-linux-objcopy --gap-fill=0xff -O binary u-boot u-boot.bin

$(obj)u-boot.bin: $(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@

$(obj)u-boot.img: $(obj)u-boot.bin
./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.dis: $(obj)u-boot
$(OBJDUMP) -d $< > $@

# ojdump -x：显示所有header的内容

# sed -n 安静模式

# .*(__u_boot_cmd_.*) 替换成 -u

# uniq 删除文件中的重复行

# 使用$(LDFLAGS)作为连接脚本

# --start-group $(__LIBS) --end-group

# 生成ELF文件u-boot 和连接时内存分配图文件u-boot.map。

$(obj)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

$(OBJS):
# $(MAKE) -C cpu/arm920 $(notdir $@)
$(MAKE) -C cpu/$(CPU) $(if $(REMOTE_BUILD),$@,$(notdir $@))

$(LIBS):
# $(MAKE) -C $(dir $@) 
$(MAKE) -C $(dir $(subst $(obj),,$@))

$(SUBDIRS):
$(MAKE) -C $@ all

$(NAND_SPL): version
$(MAKE) -C nand_spl/board/$(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

version:
# -n 不回显
@echo -n "#define U_BOOT_VERSION \"U-Boot " > $(VERSION_FILE); \
echo -n "$(U_BOOT_VERSION)" >> $(VERSION_FILE); \
echo -n $(shell $(CONFIG_SHELL) $(TOPDIR)/tools/setlocalversion \
$(TOPDIR)) >> $(VERSION_FILE); \
echo "\"" >> $(VERSION_FILE)

gdbtools:
$(MAKE) -C tools/gdb all || exit 1

updater:
$(MAKE) -C tools/updater all || exit 1

env:
$(MAKE) -C tools/env all || exit 1

# depend 和 dep，进入SUBDIRS下各个目录，生成 _depend文件

# _depend文件列出每个目标文件的依赖文件

# $$表示生成字符串

# for in do done

depend dep:
for dir \
in $(SUBDIRS) ; \
do $(MAKE) -C $$dir _depend ; \
done

tags ctags:
ctags -w -o $(OBJTREE)/ctags `find $(SUBDIRS) include \
lib_generic board/$(BOARDDIR) cpu/$(CPU) lib_$(ARCH) \
fs/cramfs fs/fat fs/fdos fs/jffs2 \
net disk rtc dtt drivers drivers/sk98lin common \
\( -name CVS -prune \) -o \( -name '*.[ch]' -print \)`

etags:
etags -a -o $(OBJTREE)/etags `find $(SUBDIRS) include \
lib_generic board/$(BOARDDIR) cpu/$(CPU) lib_$(ARCH) \
fs/cramfs fs/fat fs/fdos fs/jffs2 \
net disk rtc dtt drivers drivers/sk98lin common \
\( -name CVS -prune \) -o \( -name '*.[ch]' -print \)`

# U-Boot的符号表，包含了U-Boot的全局变量和函数的地址信息

# grep -v 反向选择

$(obj)System.map: $(obj)u-boot
@$(NM) $< | \
grep -v '\(compiled\)\|\(\.o$$\)\|\( [aUw] \)\|\(\.\.ng$$\)\|\(LASH[RL]DI\)' | \
sort > $(obj)System.map

#########################################################################

else

all $(obj)u-boot.hex $(obj)u-boot.srec $(obj)u-boot.bin \

$(obj)u-boot.img $(obj)u-boot.dis $(obj)u-boot \

$(SUBDIRS) version gdbtools updater env depend \

dep tags ctags etags $(obj)System.map:
@echo "System not configured - see README" >&2
@ exit 1

endif #ifeq ($(OBJTREE)/include/config.mk,$(wildcard $(OBJTREE)/include/config.mk))

.PHONY : CHANGELOG

CHANGELOG:
git log --no-merges U-Boot-1_1_5.. | \
unexpand -a | sed -e 's/\s\s*$$//' > $@

#########################################################################

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

#========================================================================

# ARM

#========================================================================

# unconfig去掉include/config.h，include/config.mk，board/*/config.tmp，board/*/*/config.tmp

# $(@:_config=) 去掉_config，这里是100ask24x0 $(text:patternA=patternB)

100ask24x0_config: unconfig
@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0

# $(@:_config=) 去掉_config，这里是smdk2410

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

#########################################################################

#########################################################################

#########################################################################

#########################################################################

clean:
find $(OBJTREE) -type f \
\( -name 'core' -o -name '*.bak' -o -name '*~' \
-o -name '*.o'  -o -name '*.a'  \) -print \
| xargs rm -f
rm -f $(obj)examples/hello_world $(obj)examples/timer \
 $(obj)examples/eepro100_eeprom $(obj)examples/sched \
 $(obj)examples/mem_to_mem_idma2intr $(obj)examples/82559_eeprom \
 $(obj)examples/smc91111_eeprom $(obj)examples/interrupt \
 $(obj)examples/test_burst
rm -f $(obj)tools/img2srec $(obj)tools/mkimage $(obj)tools/envcrc \
$(obj)tools/gen_eth_addr
rm -f $(obj)tools/mpc86x_clk $(obj)tools/ncb
rm -f $(obj)tools/easylogo/easylogo $(obj)tools/bmp_logo
rm -f $(obj)tools/gdb/astest $(obj)tools/gdb/gdbcont $(obj)tools/gdb/gdbsend
rm -f $(obj)tools/env/fw_printenv $(obj)tools/env/fw_setenv
rm -f $(obj)board/cray/L1/bootscript.c $(obj)board/cray/L1/bootscript.image
rm -f $(obj)board/netstar/eeprom $(obj)board/netstar/crcek $(obj)board/netstar/crcit
rm -f $(obj)board/netstar/*.srec $(obj)board/netstar/*.bin
rm -f $(obj)board/trab/trab_fkt $(obj)board/voiceblue/eeprom
rm -f $(obj)board/integratorap/u-boot.lds $(obj)board/integratorcp/u-boot.lds
rm -f $(obj)include/bmp_logo.h
rm -f $(obj)nand_spl/u-boot-spl $(obj)nand_spl/u-boot-spl.map

clobber: clean
find $(OBJTREE) -type f \( -name .depend \
-o -name '*.srec' -o -name '*.bin' -o -name u-boot.img \) \
-print0 \
| xargs -0 rm -f
rm -f $(OBJS) $(obj)*.bak $(obj)ctags $(obj)etags $(obj)TAGS $(obj)include/version_autogenerated.h
rm -fr $(obj)*.*~
rm -f $(obj)u-boot $(obj)u-boot.map $(obj)u-boot.hex $(ALL)
rm -f $(obj)tools/crc32.c $(obj)tools/environment.c $(obj)tools/env/crc32.c
rm -f $(obj)tools/inca-swap-bytes $(obj)cpu/mpc824x/bedbug_603e.c
rm -f $(obj)include/asm/proc $(obj)include/asm/arch $(obj)include/asm
[ ! -d $(OBJTREE)/nand_spl ] || find $(obj)nand_spl -lname "*" -print | xargs rm -f

ifeq ($(OBJTREE),$(SRCTREE))

mrproper \

distclean: clobber unconfig

else

mrproper \

distclean: clobber unconfig
rm -rf $(OBJTREE)/*

endif

backup:
F=`basename $(TOPDIR)` ; cd .. ; \
gtar --force-local -zcvf `date "+$$F-%Y-%m-%d-%T.tar.gz"` $$F

#########################################################################