本文主要探讨210的主Makefile。
Makefile
uboot版本号：
VERSION：主板本号
PATCHLEVEL：次版本号
SUBLEVEL：再次版本号
EXTRAVERSION:附加信息
VERSION = 1
PATCHLEVEL = 3
SUBLEVEL = 4
EXTRAVERSION =
U_BOOT_VERSION = $(VERSION).$(PATCHLEVEL).$(SUBLEVEL)$(EXTRAVERSION)
VERSION_FILE = $(obj)include/version_autogenerated.hroot@kaxi-virtual-machine:~/qt_x210v3s_160307/uboot# cat include/version_autogenerated.h
#define U_BOOT_VERSION "U-Boot 1.3.4" 宿主机参数
HOSTARCH:宿主机架构
HOSTOS:宿主机系统
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/ppc64/ppc/ \-e s/macppc/ppc/)HOSTOS := $(shell uname -s | tr '[:upper:]' '[:lower:]' | \sed -e 's/\(cygwin\).*/cygwin/')export HOSTARCH HOSTOS 静默编译
make -s
# Allow for silent builds
ifeq (,$(findstring s,$(MAKEFLAGS)))
XECHO = echo
else
XECHO = :
endif
指定编译结果路径
O参数（优先级高）make O=/tmp/build distcleanmake O=/tmp/build NAME_configmake O=/tmp/build all设置环境变量export BUILD_DIR=/tmp/buildmake distcleanmake NAME_configmake all
OBJTREE：默认当前目录,O参数可指定输出目录
SRCTREE: 源码目录(uboot一级目录)
ifdef O
ifeq ("$(origin O)", "command line")
BUILD_DIR := $(O)
endif
endififneq ($(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))
SRCTREE := $(CURDIR)
TOPDIR := $(SRCTREE)
LNDIR := $(OBJTREE)
export TOPDIR SRCTREE OBJTREEMKCONFIG := $(SRCTREE)/mkconfig
export MKCONFIGifneq ($(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 := $(SRCTREE)/
else
obj :=
src :=
endif
export obj src# Make sure CDPATH settings don't interfere
unexport CDPATH开发板配置
ifeq ($(obj)include/config.mk,$(wildcard $(obj)include/config.mk))# load ARCH, BOARD, and CPU configuration
include $(obj)include/config.mk
export ARCH CPU BOARD VENDOR SOCmake x210_sd_config(调用mkconfig脚本) ==> include/config.mk
x210_nand_config : unconfig@$(MKCONFIG) $(@:_config=) arm s5pc11x x210 samsung s5pc110@echo "TEXT_BASE = 0xc3e00000" > $(obj)board/samsung/x210/config.mkroot@kaxi-virtual-machine:~/qt_x210v3s_160307/uboot# cat include/config.mk
ARCH = arm
CPU = s5pc11x
BOARD = x210
VENDOR = samsung
SOC = s5pc110编译工具链
CROSS_COMPILE:工具链(可外部定义：路径(/usr/local/arm/arm-2009q3/bin/)+工具链标签(arm-none-linux-gnueabi-))
$(TOPDIR)/config.mk(94-107定义完整工具链：路径+工具链标签+gcc)
#
# Include the make variables (CC, etc...)
#
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 = $(CROSS_COMPILE)RANLIB Makefile(291)开始编译目标
unconfig目标可多次配置
x210_nand_config : unconfig@$(MKCONFIG) $(@:_config=) arm s5pc11x x210 samsung s5pc110@echo "TEXT_BASE = 0xc3e00000" > $(obj)board/samsung/x210/config.mk
解析config.mk
$(TOPDIR)/config.mk(uboot/config.mk)
加载宏(开发板配置)(112)
# Load generated board configuration
sinclude $(OBJTREE)/include/autoconf.mk 文件指导uboot编译过程,包含CONFIG_xxx宏它由源码目录inlcude/configs/xxx.h头文件生成(其他开发板)
210使用include/configs/x210_sd.h
加载链接脚本(142-149,board/samsung/x210/u-boot.lds)
ifndef LDSCRIPT
#LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds.debug
ifeq ($(CONFIG_NAND_U_BOOT),y)
LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot-nand.lds
else
LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds
endif
定义链接脚本地址(156-158,board/samsung/x210/config.mk)
ifneq ($(TEXT_BASE),)
CPPFLAGS += -DTEXT_BASE=$(TEXT_BASE)
endifroot@kaxi-virtual-machine:~/qt_x210v3s_160307/uboot# cat board/samsung/x210/config.mk
TEXT_BASE = 0xc3e00000TEXT_BASE是uboot链接地址由于启用虚拟地址映射,C3E00000地址等于0x23E00000
自动推导规则(239-256）
ifndef REMOTE_BUILD%.s: %.S$(CPP) $(AFLAGS) -o $@ $<
%.o: %.S$(CC) $(AFLAGS) -c -o $@ $<
%.o: %.c$(CC) $(CFLAGS) -c -o $@ $<else$(obj)%.s: %.S$(CPP) $(AFLAGS) -o $@ $<
$(obj)%.o: %.S$(CC) $(AFLAGS) -c -o $@ $<
$(obj)%.o: %.c$(CC) $(CFLAGS) -c -o $@ $<
endif
解析mkconfig(uboot/mkconfig)
x210_nand_config : unconfig@$(MKCONFIG) $(@:_config=) arm s5pc11x x210 samsung s5pc110@echo "TEXT_BASE = 0xc3e00000" > $(obj)board/samsung/x210/config.mk 6个参数 :$(@:_config=) arm s5pc11x x210 samsung s5pc110
$1: x210_sd
$2: arm
$3: s5pc11x
$4: x210
$5: samsumg
$6: s5pc110
$# = 6
BOARD_NAME=x210_sd
创建符号链接(33-118,便于移植)
uboot/include:asm -> asm-arm
uboot/inlcude/asm-arm:arch->arch-s5pc11x
uboot/include:regs.h->s5pc110.h
uboot/include/asm-arm:proc->proc-armv
创建include/config.mk文件用于主Makefile配置开发板（123-129）
#
# Create include file for Make
#
echo "ARCH = $2" > config.mk
echo "CPU = $3" >> config.mk
echo "BOARD = $4" >> config.mk[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC = $6" >> config.mk默认追加#include <configs/x210_sd.h>(开发板配置宏)到include/config.h（134-141）
...APPEND=no # Default: Create new config file...#
# Create board specific header file
#
if [ "$APPEND" = "yes" ] # Append to existing config file
thenecho >> config.h
else> config.h # Create new config file
fi
echo "/* Automatically generated - do not edit */" >>config.h
echo "#include <configs/$1.h>" >>config.h链接脚本(uboot/board/samsung/x210/u-boot.lds)
ENTRY(_start)程序入口地址
指定链接地址:-Ttext 0x00000000;(优先级高),链接脚本SECTIONS中定义. = 0x00000000
uboot链接地址用-Ttext指定(make x210_sd_config ==> uboot/board/samsung/x210/config.mk(定义TEXT_BASE))
链接脚本*(.text)前部分为前16KB(基础的初始化)其余为16KB之后，便于烧录,
链接脚本除.text .data .rodata .bss段还有自定义段(.u_boot_cmd)
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
/*OUTPUT_FORMAT("elf32-arm", "elf32-arm", "elf32-arm")*/
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{. = 0x00000000;. = ALIGN(4);.text :{cpu/s5pc11x/start.o (.text)cpu/s5pc11x/s5pc110/cpu_init.o (.text)board/samsung/x210/lowlevel_init.o (.text)cpu/s5pc11x/onenand_cp.o (.text) cpu/s5pc11x/nand_cp.o (.text) cpu/s5pc11x/movi.o (.text) common/secure_boot.o (.text) common/ace_sha1.o (.text)cpu/s5pc11x/pmic.o (.text)*(.text)}. = ALIGN(4);.rodata : { *(.rodata) }. = ALIGN(4);.data : { *(.data) }. = ALIGN(4);.got : { *(.got) }__u_boot_cmd_start = .;.u_boot_cmd : { *(.u_boot_cmd) }__u_boot_cmd_end = .;. = ALIGN(4);.mmudata : { *(.mmudata) }. = ALIGN(4);__bss_start = .;.bss : { *(.bss) }_end = .;
}
