最近看Omapl138UBOOT主Makefile的一些整理
如下：
VERSION = 2012
PATCHLEVEL = 04
SUBLEVEL = 01
EXTRAVERSION =
ifneq “$(SUBLEVEL)” “”
U_BOOT_VERSION =
$ (VERSION).$ (PATCHLEVEL).$ (SUBLEVEL)$(EXTRAVERSION)
else
U_BOOT_VERSION =
$ (VERSION).$ (PATCHLEVEL)$(EXTRAVERSION)
endif
TIMESTAMP_FILE =
$(obj)include/generated/timestamp_autogenerated.h
VERSION_FILE =
$(obj)include/generated/version_autogenerated.h
| 變數名 | 含義 |
|---|---|
| U_BOOT_VERSION | 2012.04.01 |
| TIMESTAMP_FILE | include/generated/timestamp_autogenerated.h |
| VERSION_FILE | include/generated/version_autogenerated.h |
HOSTARCH := $(shell uname -m | \ sed -e s/i.86/x86/ \ -e s/sun4u/sparc64/ \ -e s/arm.*/arm/ \ -e s/sa110/arm/ \ -e s/ppc64/powerpc/ \ -e s/ppc/powerpc/ \ -e s/macppc/powerpc/\ -e s/sh.*/sh/) HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | \ sed -e 's/\(cygwin\).*/cygwin/')
“sed
–e”表示後面跟的是一串命令指令碼，而表示式“s/abc/def/”表示要從標準輸入中，查詢到內容為“abc”的，然後替換成“def”。其中“abc”表示式用可以使用“.”作為萬用字元。
命令“uname –m”將輸出主機CPU的體系架構型別。作者的電腦使用Intel Core2系列的CPU，因此“uname –m”輸出“i686”。 “i686”可以匹配命令“sed -e
s/i.86/x86/”中的“i.86”，因此在作者的機器上執行Makefile，HOSTARCH將被設定成“x86” 。
“uname
–s”輸出主機核心名字，作者使用Linux發行版Ubuntu10.04，因此“uname –s”結果是“Linux”。“tr
'[:upper:]' '[:lower:]'”作用是將標準輸入中的所有大寫字母轉換為響應的小寫字母。因此執行結果是將HOSTOS 設定為“linux”。
# Set shell to bash if possible, otherwise
fall back to sh
SHELL := $(shell if [ -x "$$BASH"
]; then echo $$BASH; \
else
if [ -x /bin/bash ]; then echo /bin/bash; \
else
echo sh; fi; fi)
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
#因為沒有定義MAKEFLAGS，所以XECHO=echo
#########################################################################
#
# 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'
#
# 2) Set environement variable BUILD_DIR to
point to the desired location
# 'export BUILD_DIR=/tmp/build'
# 'make'
#
# The second approach can also be used with
a MAKEALL script
# 'export BUILD_DIR=/tmp/build'
# './MAKEALL'
#
# 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.
#
ifdef O
ifeq ("$(origin O)",
"command line")
BUILD_DIR := $(O)
endif
endif
ifneq ($(BUILD_DIR),)
saved-output := $(BUILD_DIR)
# Attempt to create a output 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),)
OBJTREE :=
$(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))
SPLTREE :=
$(OBJTREE)/spl
SRCTREE :=
$(CURDIR)
TOPDIR :=
$(SRCTREE)
LNDIR :=
$(OBJTREE)
export TOPDIR
SRCTREE OBJTREE SPLTREE
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
CURDIR變數指示Make當前的工作目錄，由於當前Make在U-Boot頂層目錄執行Makefile，因此CURDIR此時就是U-Boot頂層目錄。
執行完上面的程式碼後， SRCTREE，src變數就是U-Boot程式碼頂層目錄，而OBJTREE，obj變數就是輸出目錄，若沒有定義BUILD_DIR環境變數，則SRCTREE，src變數與OBJTREE，obj變數都是U-Boot原始碼目錄。而MKCONFIG則表示U-Boot根目錄下的mkconfig指令碼。
| 變數 | 含義 |
|---|---|
| OBJTREE | Omapl138/uboot |
| SPLTREE | Omapl138/uboot/spl |
| SRCTREE | Omapl138/uboot |
| TOPDIR | Omapl138/uboot |
| LNDDIR | Omapl138/uboot |
| src | Omapl138/uboot |
| obj | Omapl138/uboot |
| MKCONFIG | Omapl138/uboot/mkconfig |
# 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)
# The "examples" conditionally
depend on U-Boot (say, when USE_PRIVATE_LIBGCC
# is "yes"), so compile examples
after U-Boot is compiled.
SUBDIR_TOOLS = tools
SUBDIR_EXAMPLES = examples/standalone
examples/api
SUBDIRS = $(SUBDIR_TOOLS)
.PHONY : $(SUBDIRS) $(VERSION_FILE)
$(TIMESTAMP_FILE)
ifeq ($(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
當makefile中有兩個相同目標的時候，會執行後一個目標。因為後一個目標會過載前一個。如果你 執行make的時候沒有帶任何其他目標。單獨的一個make。可以避免以autoconf.mk.dep裡面的include/autoconf.mk作為錯誤目標。如果你執行make的時候帶了目標。這個all:有不有都無所謂。
ifndef CONFIG_SANDBOX
SUBDIRS += $(SUBDIR_EXAMPLES)
endif
# load ARCH, BOARD, and CPU configuration
include $(obj)include/config.mk
export ARCH
CPU BOARD VENDOR SOC
#包含include/config.mk檔案，這個檔案是在makexxx_config過程中產生的
# set default to nothing for native builds
ifeq ($(HOSTARCH),$(ARCH))
CROSS_COMPILE ?=
endif
#HOSTARCH是x86的，目標是arm的，所以不執行
這個CROSS_COMPILE是通過命令列引入的，make CROSS_COMPILE=arm-none-linux-gnueabi-
# load other configuration
include $(TOPDIR)/config.mk
#包含Omapl138/uboot/mkconfig
# If board code explicitly specified
LDSCRIPT or CONFIG_SYS_LDSCRIPT, use
# that (or fail if absent). Otherwise, search for a linker script in a
# standard location.
LDSCRIPT_MAKEFILE_DIR = $(dir $(LDSCRIPT))
#用等號賦值的變數是遞迴方式擴充套件的變數。變數定義時，變數值中對其他變數的引用不會被替換展開；
#而是變數在引用它的地方替換展開的同時，它所引用的其它變數才會被一同替換展開。
#其優點是：
#這種型別變數在定義時，可以引用其它的之前沒有定義的變數（可能在後續部分定義，或者是通過make的命令列選項傳遞的變數）。
#LDSCRIPT變數就是後面才定義的
ifndef LDSCRIPT
#LDSCRIPT
:= $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds.debug
ifdef
CONFIG_SYS_LDSCRIPT
#沒有定義
#
need to strip off double quotes
LDSCRIPT
:= $(subst ",,$(CONFIG_SYS_LDSCRIPT))
#如果定義了CONFIG_SYS_LDSCRIPT，將CONFIG_SYS_LDSCRIPT代表的字串去掉雙引號後賦值給LDSCRIPT變數
endif
endif
# If there is no specified link script, we
look in a number of places for it
ifndef LDSCRIPT
ifeq
($(CONFIG_NAND_U_BOOT),y)
LDSCRIPT
:= $(TOPDIR)/board/$(BOARDDIR)/u-boot-nand.lds
ifeq
($(wildcard $(LDSCRIPT)),)
LDSCRIPT
:= $(TOPDIR)/$(CPUDIR)/u-boot-nand.lds
endif
endif
ifeq
($(wildcard $(LDSCRIPT)),)
LDSCRIPT
:= $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds
endif
ifeq
($(wildcard $(LDSCRIPT)),)
LDSCRIPT
:= $(TOPDIR)/$(CPUDIR)/u-boot.lds
endif
ifeq
($(wildcard $(LDSCRIPT)),)
LDSCRIPT
:= $(TOPDIR)/arch/$(ARCH)/cpu/u-boot.lds
#
We don't expect a Makefile here
LDSCRIPT_MAKEFILE_DIR
=
endif
ifeq
($(wildcard $(LDSCRIPT)),)
$(error could not find linker script)
endif
endif
在config.mk中有如下定義：
BOARDDIR =$ (VENDDOR)/$( BOARD)
CPUDIR=arch/$ (ARCH)/cpu/$(CPU)
ifneq
($ (SRCTREE)/$ (CPUDIR),$ (wildcard $ (SRCTREE)/$ (CPUDIR)))
CPUDIR= arch/$(ARCH)/cpu
結合boards.cfg中的定義：
| 變數名 | 定義 |
|---|---|
| ARCH | arm |
| CPU | arm926ejs |
| BOARD name | da8xxevm |
| Vendor | davinci |
| SOC | davinci |
綜上：
BOARDDIR=davinci/da8xxevm/
CPUDIF=arch/arm/cpu/arm926ejs
#註釋寫的很明確，如果沒有用CONFIG_SYS_LDSCRIPT指定LDSCRIPT，那麼就在幾個地方搜
#第一個地方:如果CONFIG_NAND_U_BOOT是y，就用u-boot-nand.lds但是這裡沒有這個定義
#第一個地方沒找到，就找第二個地方:uboot/board/davinci /da8xxevm這個目錄沒有u-boot.lds檔案
#第二個地方沒找到，就找第三個地方:其中CPUDIR是在頂層的config.mk中定義的，在arch/arm/cpu/arm926ejs中找這個目錄也沒有
#第三個地方沒找到，就找第四個地方:arch/arm/cpu/u-boot.lds，這裡就找到了！！！！
#########################################################################
# U-Boot objects....order is important
(i.e. start must be first)
OBJS
= $(CPUDIR)/start.o
OBJS =arch/arm/cpu/arm926ejs/start.o
ifeq ($(CPU),x86)
OBJS += $(CPUDIR)/start16.o
OBJS += $(CPUDIR)/resetvec.o
endif
ifeq ($(CPU),ppc4xx)
OBJS += $(CPUDIR)/resetvec.o
endif
ifeq ($(CPU),mpc85xx)
OBJS += $(CPUDIR)/resetvec.o
endif
均不滿足
OBJS := $(addprefix $(obj),$(OBJS))
OBJS:=arch/arm/cpu/arm926ejs/start.o
LIBS
= lib/libgeneric.o
LIBS += lib/lzma/liblzma.o
LIBS += lib/lzo/liblzo.o
LIBS += lib/zlib/libz.o
LIBS += $(shell if [ -f
board/$(VENDOR)/common/Makefile ]; then echo \
"board/$(VENDOR)/common/lib$(VENDOR).o";
fi)
#-f表示該檔案為常規檔案，經查該檔案不存在
LIBS += $(CPUDIR)/lib$(CPU).o
LIBS+= arch/arm/cpu/arm926ejs/libarm926ejs.o
ifdef SOC
LIBS += $(CPUDIR)/$(SOC)/lib$(SOC).o
LIBS+=
arch/arm/cpu/arm926ejs/davinci/libdavinci.o
endif
ifeq ($(CPU),ixp)
LIBS += arch/arm/cpu/ixp/npe/libnpe.o
endif
ifeq ($(CONFIG_OF_EMBED),y)
LIBS += dts/libdts.o
endif
LIBS += arch/$(ARCH)/lib/lib$(ARCH).o
LIBS+= arch/arm/libarm.o
LIBS += fs/cramfs/libcramfs.o
fs/fat/libfat.o fs/fdos/libfdos.o fs/jffs2/libjffs2.o \
fs/reiserfs/libreiserfs.o
fs/ext2/libext2fs.o fs/yaffs2/libyaffs2.o \
fs/ubifs/libubifs.o
LIBS += net/libnet.o
LIBS += disk/libdisk.o
LIBS +=
drivers/bios_emulator/libatibiosemu.o
LIBS += drivers/block/libblock.o
LIBS += drivers/dma/libdma.o
LIBS += drivers/fpga/libfpga.o
LIBS += drivers/gpio/libgpio.o
LIBS += drivers/hwmon/libhwmon.o
LIBS += drivers/i2c/libi2c.o
LIBS += drivers/input/libinput.o
LIBS += drivers/misc/libmisc.o
LIBS += drivers/mmc/libmmc.o
LIBS += drivers/mtd/libmtd.o
LIBS += drivers/mtd/nand/libnand.o
LIBS += drivers/mtd/onenand/libonenand.o
LIBS += drivers/mtd/ubi/libubi.o
LIBS += drivers/mtd/spi/libspi_flash.o
LIBS += drivers/net/libnet.o
LIBS += drivers/net/phy/libphy.o
LIBS += drivers/pci/libpci.o
LIBS += drivers/pcmcia/libpcmcia.o
LIBS += drivers/power/libpower.o
LIBS += drivers/spi/libspi.o
ifeq ($(CPU),mpc83xx)
LIBS += drivers/qe/libqe.o
LIBS +=
arch/powerpc/cpu/mpc8xxx/ddr/libddr.o
LIBS += arch/powerpc/cpu/mpc8xxx/lib8xxx.o
endif
ifeq ($(CPU),mpc85xx)
LIBS += drivers/qe/libqe.o
LIBS += drivers/net/fm/libfm.o
LIBS +=
arch/powerpc/cpu/mpc8xxx/ddr/libddr.o
LIBS += arch/powerpc/cpu/mpc8xxx/lib8xxx.o
endif
ifeq ($(CPU),mpc86xx)
LIBS +=
arch/powerpc/cpu/mpc8xxx/ddr/libddr.o
LIBS += arch/powerpc/cpu/mpc8xxx/lib8xxx.o
endif
LIBS += drivers/rtc/librtc.o
LIBS += drivers/serial/libserial.o
ifeq ($(CONFIG_GENERIC_LPC_TPM),y)
LIBS += drivers/tpm/libtpm.o
endif
LIBS += drivers/twserial/libtws.o
LIBS += drivers/usb/eth/libusb_eth.o
LIBS += drivers/usb/gadget/libusb_gadget.o
LIBS += drivers/usb/host/libusb_host.o
LIBS += drivers/usb/musb/libusb_musb.o
LIBS += drivers/usb/phy/libusb_phy.o
LIBS += drivers/usb/ulpi/libusb_ulpi.o
LIBS += drivers/video/libvideo.o
LIBS += drivers/watchdog/libwatchdog.o
LIBS += common/libcommon.o
LIBS += lib/libfdt/libfdt.o
LIBS += api/libapi.o
LIBS += post/libpost.o
ifneq
($(CONFIG_AM33XX)$(CONFIG_OMAP34XX)$(CONFIG_OMAP44XX)$(CONFIG_OMAP54XX),)
LIBS +=
$(CPUDIR)/omap-common/libomap-common.o
endif
ifeq ($(SOC),mx5)
LIBS +=
$(CPUDIR)/imx-common/libimx-common.o
endif
ifeq ($(SOC),mx6)
LIBS +=
$(CPUDIR)/imx-common/libimx-common.o
endif
ifeq ($(SOC),s5pc1xx)
LIBS +=
$(CPUDIR)/s5p-common/libs5p-common.o
endif
ifeq ($(SOC),exynos)
LIBS +=
$(CPUDIR)/s5p-common/libs5p-common.o
endif
LIBS := $(addprefix $(obj),$(sort $(LIBS)))
.PHONY : $(LIBS)
LIBBOARD = board/$(BOARDDIR)/lib$(BOARD).o
LIBBOARD := $(addprefix $(obj),$(LIBBOARD))
#為LIBBOARD增加字首，board/davinci/da8xxevm/libda8xxevm.o
# Add GCC lib
ifdef USE_PRIVATE_LIBGCC
ifeq ("$(USE_PRIVATE_LIBGCC)",
"yes")
PLATFORM_LIBGCC = $(OBJTREE)/arch/$(ARCH)/lib/libgcc.o
else
PLATFORM_LIBGCC = -L $(USE_PRIVATE_LIBGCC)
-lgcc
endif
else
PLATFORM_LIBGCC := -L $(shell dirname
`$(CC) $(CFLAGS) -print-libgcc-file-name`) -lgcc
#dirname 命令讀取指定路徑名刪除最後一個“/”（斜槓）及其後面的字元，保留其他部分，並寫結果到標準輸出。如果最後一個“/”後無字元，dirname
命令使用倒數第二個“/”，並忽略其後的所有字元。
CFLGS:=$(CPPFLAGS) -Wall
-Wstrict-prototypes
1）USE_PRIVATE_LIBGCC = yes，從 /arch/arm/lib 中獲得 libgcc.a
2）USE_PRIVATE_LIBGCC = path+file，從 指定的路徑獲得 libgcc.a
3）如果沒有配置USE_PRIVATE_LIBGCC，就從工具鏈 libgcc路徑獲得。
我們這裡沒有定義使用者私有GCC庫，所以執行ifdef的else分支
PLATFORM_LIBGCC
= -L $ (shell dirname $(CC) $(CFLAGS) -print-libgcc-file-name) -lgcc
CC和CFLAGS都是make的隱含變數，CC表示C語言編譯器，預設為：‘cc’。cflags表示執行CC時的命令列引數
但是在這裡並不是使用“cc”這個編譯器，在頂層的config.mk檔案中我們可以找到關於$ (CC)和$(CFLAGS)的定義，如下：
dirname
$(CC) $(CFLAGS) -print-libgcc-file-name取得交叉編譯器的libgcc.a的絕對路徑
CC =
$(CROSS_COMPILE)gcc // CROSS_COMPILE = arm-none-linux-gnueabi-
//所以這裡：CC = arm-none-linux-gnueabi-gcc
# 沒有定義BUILD_TAG，執行else分支,賦值CFLAGS
ifdef BUILD_TAG
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes \
-DBUILD_TAG='"$(BUILD_TAG)"'
else
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes
endif
##########################################################
# 利用call函式，使得$1=cc-option ,$2=-fno-stack-protector
# CFLAGS_SSP= $1$2 = -fno-stack-protector,然後把CFLAGS_SSP
# 追加給CFLAGS
CFLAGS_SSP := $(call cc-option,-fno-stack-protector)
# ARFLAGS = $(error update your Makefile to use cmd_link_o_target and not AR)
# RELFLAGS=$(PLATFORM_RELFLAGS)=-fno-common -ffixed-r8 -msoft-float
# DBGFLAGS = -g
# OPTFLAGS = -Os
# OBJCFLAGS = --gap-fill=0xff
# gccincdir = $(shell $(CC) -print-file-name=include)=交叉工具鏈include目錄在宿# 主機中的位置CPPFLAGS = -g -Os -fno-common -ffixed-r8 -msoft-float -D__KERNEL__
ARFLAGS = $(error update your Makefile to use cmd_link_o_target and not AR)
RELFLAGS= $(PLATFORM_RELFLAGS)
DBGFLAGS= -g # -DDEBUG
OPTFLAGS= -Os # -fomit-frame-pointer
OBJCFLAGS += --gap-fill=0xff
gccincdir := $(shell $(CC) -print-file-name=include)
CPPFLAGS := $(DBGFLAGS) $(OPTFLAGS) $(RELFLAGS) \
-D__KERNEL__
# Enable garbage collection of un-used sections for SPL
ifeq ($(CONFIG_SPL_BUILD),y)
CPPFLAGS += -ffunction-sections -fdata-sections
LDFLAGS_FINAL += --gc-sections
endif
－L
表示：編譯程式按照－L指定的路進去尋找庫檔案，一般的在-L的後面可以一次用-l指定多個庫檔案。
-lgcc 代表連結器將連線GCC的支援庫libgcc.a
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
$(TOPDIR)/include/u-boot/u-boot.lds.h \
-DCPUDIR=$(CPUDIR)
\
$(shell
$(LD) --version | \
sed -ne 's/GNU ld version
\([0-9][0-9]*\)\.\([0-9][0-9]*\).*/-DLD_MAJOR=\1 -DLD_MINOR=\2/p')
__OBJS := $(subst $(obj),,$(OBJS))
__LIBS := $(subst $(obj),,$(LIBS)) $(subst
$(obj),,$(LIBBOARD))
#########################################################################
#########################################################################
ifneq ($(CONFIG_BOARD_SIZE_LIMIT),)
BOARD_SIZE_CHECK = \
@actual=`wc
-c [email protected] | awk '{print $$1}'`; \
limit=$(CONFIG_BOARD_SIZE_LIMIT);
\
if
test $$actual -gt $$limit; then \
echo
"[email protected] exceeds file size limit:"; \
echo
" limit: $$limit bytes"; \
echo
" actual: $$actual bytes"; \
echo
" excess: $$((actual - limit))
bytes"; \
exit
1; \
fi
else
BOARD_SIZE_CHECK =
endif
# Always append ALL so that arch
config.mk's can add custom ones
ALL-y += $(obj)u-boot.srec $(obj)u-boot.bin
$(obj)System.map
ALL-$(CONFIG_NAND_U_BOOT) +=
$(obj)u-boot-nand.bin
ALL-$(CONFIG_ONENAND_U_BOOT) +=
$(obj)u-boot-onenand.bin
ONENAND_BIN ?=
$(obj)onenand_ipl/onenand-ipl-2k.bin
ALL-$(CONFIG_SPL) +=
$(obj)spl/u-boot-spl.bin
ALL-$(CONFIG_OF_SEPARATE) +=
$(obj)u-boot.dtb $(obj)u-boot-dtb.bin
all: $(ALL-y)
$(SUBDIR_EXAMPLES)
$(obj)u-boot.dtb: $(obj)u-boot
$(MAKE)
-C dts binary
mv
$(obj)dts/dt.dtb [email protected]
$(obj)u-boot-dtb.bin: $(obj)u-boot.bin $(obj)u-boot.dtb
cat
$^ >[email protected]
$(obj)u-boot.hex: $(obj)u-boot
$(OBJCOPY)
${OBJCFLAGS} -O ihex $< [email protected]
$(obj)u-boot.srec: $(obj)u-boot
$(OBJCOPY)
-O srec $< [email protected]
$(obj)u-boot.bin: $(obj)u-boot
$(OBJCOPY)
${OBJCFLAGS} -O binary $< [email protected]
$(BOARD_SIZE_CHECK)
$(obj)u-boot.ldr: $(obj)u-boot
$(CREATE_LDR_ENV)
$(LDR)
-T $(CONFIG_BFIN_CPU) -c [email protected] $< $(LDR_FLAGS)
$(BOARD_SIZE_CHECK)
$(obj)u-boot.ldr.hex: $(obj)u-boot.ldr
$(OBJCOPY)
${OBJCFLAGS} -O ihex $< [email protected] -I binary
$(obj)u-boot.ldr.srec: $(obj)u-boot.ldr
$(OBJCOPY)
${OBJCFLAGS} -O srec $< [email protected] -I binary
$(obj)u-boot.img: $(obj)u-boot.bin
$(obj)tools/mkimage
-A $(ARCH) -T firmware -C none \
-O
u-boot -a $(CONFIG_SYS_TEXT_BASE) -e 0 \
-n
$(shell sed -n -e 's/.*U_BOOT_VERSION//p' $(VERSION_FILE) | \
sed
-e 's/"[ ]*$$/ for $(BOARD)
board"/') \
-d
$< [email protected]
$(obj)u-boot.imx: $(obj)u-boot.bin
$(obj)tools/mkimage
-n $(CONFIG_IMX_CONFIG) -T imximage \
-e
$(CONFIG_SYS_TEXT_BASE) -d $< [email protected]
$(obj)u-boot.kwb: $(obj)u-boot.bin
$(obj)tools/mkimage
-n $(CONFIG_SYS_KWD_CONFIG) -T kwbimage \
-a
$(CONFIG_SYS_TEXT_BASE) -e $(CONFIG_SYS_TEXT_BASE) -d $< [email protected]
$(obj)u-boot.sha1: $(obj)u-boot.bin
$(obj)tools/ubsha1
$(obj)u-boot.bin
$(obj)u-boot.dis: $(obj)u-boot
$(OBJDUMP)
-d $< > [email protected]
$(obj)u-boot.ubl: $(obj)spl/u-boot-spl.bin
$(obj)u-boot.bin
$(OBJCOPY)
${OBJCFLAGS} --pad-to=$(PAD_TO) -O binary $(obj)spl/u-boot-spl
$(obj)spl/u-boot-spl-pad.bin
cat
$(obj)spl/u-boot-spl-pad.bin $(obj)u-boot.bin > $(obj)u-boot-ubl.bin
$(obj)tools/mkimage
-n $(UBL_CONFIG) -T ublimage \
-e
$(CONFIG_SYS_TEXT_BASE) -d $(obj)u-boot-ubl.bin $(obj)u-boot.ubl
rm
$(obj)u-boot-ubl.bin
rm
$(obj)spl/u-boot-spl-pad.bin
$(obj)u-boot.ais: $(obj)spl/u-boot-spl.bin
$(obj)u-boot.bin
$(obj)tools/mkimage -s -n
/dev/null -T aisimage \
-e $(CONFIG_SPL_TEXT_BASE)
\
-d $(obj)spl/u-boot-spl.bin
\
$(obj)spl/u-boot-spl.ais
$(OBJCOPY) ${OBJCFLAGS} -I binary
\
--pad-to=$(CONFIG_SPL_MAX_SIZE)
-O binary \
$(obj)spl/u-boot-spl.ais
$(obj)spl/u-boot-spl-pad.ais
cat $(obj)spl/u-boot-spl-pad.ais
$(obj)u-boot.bin > \
$(obj)u-boot.ais
u-boot.ais的編譯依賴u-boot-spl.bin，u-boot.bin等檔案
$(obj)u-boot.sb: $(obj)u-boot.bin
$(obj)spl/u-boot-spl.bin
elftosb
-zdf imx28 -c $(TOPDIR)/board/$(BOARDDIR)/u-boot.bd \
-o
$(obj)u-boot.sb
ifeq ($(CONFIG_SANDBOX),y)
GEN_UBOOT = \
cd
$(LNDIR) && $(CC) $(SYMS) -T $(obj)u-boot.lds \
-Wl,--start-group
$(__LIBS) -Wl,--end-group \
$(PLATFORM_LIBS)
-Wl,-Map -Wl,u-boot.map -o u-boot
else
GEN_UBOOT = \
UNDEF_SYM=`$(OBJDUMP)
-x $(LIBBOARD) $(LIBS) | \
sed -n -e
's/.*\($(SYM_PREFIX)__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\
cd
$(LNDIR) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) $$UNDEF_SYM $(__OBJS) \
--start-group
$(__LIBS) --end-group $(PLATFORM_LIBS) \
-Map
u-boot.map -o u-boot
endif
$(obj)u-boot: depend \
$(SUBDIR_TOOLS)
$(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
$(GEN_UBOOT)
u-boot.ais的編譯依賴u-boot-spl.bin，u-boot.bin等檔案
$(obj)u-boot.sb: $(obj)u-boot.bin
$(obj)spl/u-boot-spl.bin
elftosb
-zdf imx28 -c $(TOPDIR)/board/$(BOARDDIR)/u-boot.bd \
-o
$(obj)u-boot.sb
ifeq ($(CONFIG_SANDBOX),y)
GEN_UBOOT = \
cd
$(LNDIR) && $(CC) $(SYMS) -T $(obj)u-boot.lds \
-Wl,--start-group
$(__LIBS) -Wl,--end-group \
$(PLATFORM_LIBS)
-Wl,-Map -Wl,u-boot.map -o u-boot
else
GEN_UBOOT = \
UNDEF_SYM=`$(OBJDUMP)
-x $(LIBBOARD) $(LIBS) | \
sed -n -e
's/.*\($(SYM_PREFIX)__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\
cd
$(LNDIR) && $(LD) $(LDFLAGS) $(LDFLAGS_$(@F)) $$UNDEF_SYM $(__OBJS) \
--start-group
$(__LIBS) --end-group $(PLATFORM_LIBS) \
-Map
u-boot.map -o u-boot
endif
$(obj)u-boot: depend \
$(SUBDIR_TOOLS)
$(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
$(GEN_UBOOT)
#all依賴於$(ALL) 最終生成映象檔案,注意各種依賴關係。
重點分析一下“u-boot.bin”， u-boot.bin的依賴關係是這樣的：$(obj)u-boot.bin - > $(obj)u-boot - >
depend
$(SUBDIRS) $(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
先來看看GEN_UBOOT變數的具體內容：
（1） $(OBJDUMP)
在頂層目錄的config.mk（$(TOPDIR)/config.mk ）檔案中我們可以找到該變數的定義：
OBJDUMP =
$(CROSS_COMPILE)objdump
命令列中定義了 CROSS_COMPILE=arm-none-linux-gnueabi-，所以
OBJDUMP =arm- none-linux-gnueabi
-objdump
（2） $(LIBBOARD)
LIBBOARD在Makefile中有定義。如下：
LIBBOARD =
board/
(BOARD).o
LIBBOARD :=
$(addprefix
(LIBBOARD))
展開後得到的結果是：
LIBBOARD =
$(obj)board/davinci/da8xxevm/libda8xxevm.o
（3）$(LIBS)
這個變數是新增庫了（在Makefile中定義的），內容比較多，如下：
LIBS =
lib_generic/libgeneric.a
LIBS +=
lib_generic/lzma/liblzma.a
LIBS +=
lib_generic/lzo/liblzo.a
LIBS += (VENDOR)/common/Makefile ]; then echo \
“board/
(VENDOR).a”;
fi)
LIBS +=
cpu/
(CPU).a
ifdef SOC
LIBS +=
cpu/
(SOC)/lib$(SOC).a
endif
ifeq ($(CPU),ixp)
LIBS +=
cpu/ixp/npe/libnpe.a
endif
LIBS +=
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
ifeq ($(CPU),mpc83xx)
LIBS += drivers/qe/qe.a
endif
ifeq ($(CPU),mpc85xx)
LIBS += drivers/qe/qe.a
LIBS += cpu/mpc8xxx/ddr/libddr.a
LIBS +=
cpu/mpc8xxx/lib8xxx.a
endif
ifeq ($(CPU),mpc86xx)
LIBS +=
cpu/mpc8xxx/ddr/libddr.a
LIBS +=
cpu/mpc8xxx/lib8xxx.a
endif
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
LBS +=
drivers/usb/phy/libusb_phy.a
LIBS +=
drivers/video/libvideo.a
LIBS += drivers/watchdog/libwatchdog.a
LIBS +=
common/libcommon.a
LIBS += libfdt/libfdt.a
LIBS += api/libapi.a
LIBS += post/libpost.a
從這些新增進來的這些庫的檔名，大概可以知道這些庫的用途了，包含了cup的配置、drivers驅動程式、api等，這裡就不列出了。
（3）$(SYM_PREFIX)
沒有定義這個變數，
（4） $(LNDIR)
LNDIR := $(OBJTREE) ，前面分析知道 OBJTREE就是頂層目錄了。
（5） $(LD)
在config.mk中有定義
LD =
$(CROSS_COMPILE)ld
結果為： LD = arm-none-linux-gnueabi-ld
咱們可以用type命令檢視一下“ arm-linux-ld”命令在哪裡：
（6）$(LDFLAGS)、$(LDFLAGS_$(@F))
在config.mk中有定義 ：
LDFLAGS
+=$(PLATFORM_LDFLAGS)
LDFLAGS_FINAL += -Bstatic
# 設定U-boot的連結選項
LDFLAGS_u-boot += -T $(obj)u-boot.lds $(LDFLAGS_FINAL)
ifneq ($(CONFIG_SYS_TEXT_BASE),)
LDFLAGS_u-boot += -Ttext $(CONFIG_SYS_TEXT_BASE)
endif
# 設定U-boot的連結選項，當uboot是採用spl時的情況
LDFLAGS_u-boot-spl += -T $(obj)u-boot-spl.lds $(LDFLAGS_FINAL)
ifneq ($(CONFIG_SPL_TEXT_BASE),)
LDFLAGS_u-boot-spl += -Ttext $(CONFIG_SPL_TEXT_BASE)
endif
（7） $(__OBJS)和 $(__LIBS)
在config.mk中有定義 ：
__OBJS :=
$(subst $(obj),,$(OBJS))
__LIBS :=
$(subst $(obj),,$(LIBS)) $(subst $(obj),,$(LIBBOARD))
subst函式的使用規則：
$(subst from,to,text)
在文字‘text’中使用‘to’替換每一處‘from’。
結果就是：將變數OBJS內容裡的$(obj)替換成空，然後賦給 __OBJS
（8）$(PLATFORM_LIBS)
PLATFORM_LIBS在Makefile中定義為：
PLATFORM_LIBS += $(PLATFORM_LIBGCC)
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
$(OBJS): depend
$(MAKE)
-C $(CPUDIR) $(if $(REMOTE_BUILD),[email protected],$(notdir [email protected]))
$(LIBS): depend
$(SUBDIR_TOOLS)
$(MAKE)
-C $(dir $(subst $(obj),,[email protected]))
$(LIBBOARD): depend $(LIBS)
$(MAKE)
-C $(dir $(subst $(obj),,[email protected]))
$(SUBDIRS): depend
$(MAKE)
-C [email protected] all
$(SUBDIR_EXAMPLES): $(obj)u-boot
$(LDSCRIPT): depend
$(MAKE)
-C $(dir [email protected]) $(notdir [email protected])
$(obj)u-boot.lds: $(LDSCRIPT)
$(CPP)
$(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - <$^ >[email protected]
#CPP=$(CC)
-E=$(CORSS_COMPILE)gcc -E=arm-none-linux-gnueabi-gcc -E
# LDPPFLAGS += \
-include $(TOPDIR)/include/u-boot/u-boot.lds.h \具體的位置是/include/u-boot/u-boot.lds.h
-DCPUDIR=$(CPUDIR) \
$(shell $(LD) --version | \
sed -ne 's/GNU ld
version \([0-9][0-9]*\)\.\([0-9][0-9]*\).*/-DLD_MAJOR=\1 -DLD_MINOR=\2/p')
預設變數“ CPP” :C
程式的前處理器（輸出是標準輸出裝置）。預設命令是“$(CC) –E”。
-Dmacro：定義巨集macro,巨集的內容定義為字串`1'. 這裡
-D__ASSEMBLY__ 相當於 #define __ASSEMBLY__ ‘1’
。-D 是選項，__ASSEMBLY__ 相當於一個巨集。