u-boot(二)makefile

u-boot(二)makefile

引入

我们是怎么编译的?先执行配置make 100ask24x0_config,然后编译make.所以在顶层目录下的Makefile一定存在这个100ask24x0_config.我们就从这里入手

目录结构(1.1.6)

  • 总体来说,命令是存放在common中,比如common中的cmd_nand.会调用驱动层的driver中的nand/nandbase.c,再去调用平台级别cpu,以及单板的(IO等)board.分为四层结构如下:
  • 在硬件层次,从上往下分别是 架构相关> CPU相关> 单板相关
  • 具体的说明在顶层的README中有讲
--------------------------------------------------
	lib_generic   			common 
--------------------------------------------------
	post	net		fs		disk		 	
--------------------------------------------------
	dtt		nand_spl	rtc		drivers
--------------------------------------------------
	board		cpu		lib_xxx
目录 说明
lib_generic 通用的库文件(crc)等
common 通用程序,命令在这里
include 头文件和配置文件
asm-arm
config
↑↑↑↑↑↑↑↑↑↑↑ -------用户接口-------
disk 硬盘接口
net 网络驱动
fs 文件系统
↑↑↑↑↑↑↑↑↑↑↑ -------中间层-------
dtt 温度等其他传感器驱动
rtc 时钟
nand_spl nand启动相关
drivers 驱动程序
↑↑↑↑↑↑↑↑↑↑↑ --------驱动层--------
cpu 针对具体cpu
Lib_xxx 架构通用的文件
board 开发板相关的,Io等相关
↑↑↑↑↑↑↑↑↑↑↑ ------CPU相关,单板相关-------
doc 文档
example 测试程序
tools 制作u-boot格式映象工具等

顶层的mkconfig 配置了交叉编译工具的版本,链接参数等

配置文件

100ask24x0_config	:	unconfig
	@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0
###################################################################################
#                                                                                 #
#        首先是进行单板的配置                                                       #
#        make 100ask24x0_config                                                   #
#                                                                                 #
###################################################################################
100ask24x0_config	:	unconfig
	@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0

##################################################################################
#unconfig 执行的操作如下,可以先不去管它
unconfig:
	@rm -f $(obj)include/config.h $(obj)include/config.mk \
		$(obj)board/*/config.tmp $(obj)board/*/*/config.tmp

##################################################################################
#当前目录
SRCTREE		:= $(CURDIR)
# 当前目录下的mkconfig文件
MKCONFIG	:= $(SRCTREE)/mkconfig
export MKCONFIG
##################################################################################
# $@表示目标,在$()中的@也表示目标,接下去的是字符串替换,也就是将目标中的_config 替换为空
# 开头@ 表示不回显
@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0
#也就是相当于  
mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0
# 也就是调用外部shell脚本了

目标

  • 配置单板的名字 100ask24x0

  • 建立符号链接

    include/asm include/asm-arm
    include/asm-arm/arch include/asm-arm/arch-s3c24x0
    include/asm-arm/proc include/asm-arm/proc-armv
  • 建立include/config.mk,包含cpu,soc等信息

    ARCH   = arm
    CPU    = arm920t
    BOARD  = 100ask24x0
    SOC    = s3c24x0
    
  • 新建include/config.h ,开发板相关头文件,这个文件来配置裁剪uboot,所以如果要在board目录下新建一个开发板<board_name>的目录,需要在include/config 下建立<board_name>.h

    /* Automatically generated - do not edit */
    #include <configs/100ask24x0.h>
    
    

配置具体的单板

从上述第4步骤我们可以发现,单板的具体配置实在include/config/单板.h中配置的.有以下几类配置:

  1. 选项配置,用于配置系统时钟,CPU等,还有功能开关,可以理解为1级开关
  2. 参数配置,前缀为CFG_,设置malloc大小,u-boot命令选项,下载文件的默认地址,FLASH地址等

编译阶段

过程

重新来看根目录的makefile

  • 包含配置阶段设置的参数

    include $(OBJTREE)/include/config.mk
    export	ARCH CPU BOARD VENDOR SOC
    
    #ARCH   = arm
    #CPU    = arm920t
    #BOARD  = 100ask24x0
    #SOC    = s3c24x0
    
  • 配置交叉工具链

    ifeq ($(ARCH),arm)
    CROSS_COMPILE = arm-linux-
    endif
    
  • 包含启动文件,这里也就是cpu/arm920t/start.o

    OBJS  = cpu/$(CPU)/start.o
    
  • 包含库文件BOARDDIR=100ask24x0,BOARD=100ask24x0,CPU=arm920t

    IBS  = lib_generic/libgeneric.a
    LIBS += board/$(BOARDDIR)/lib$(BOARD).a
    LIBS += cpu/$(CPU)/lib$(CPU).a
    ifdef SOC
    LIBS += cpu/$(CPU)/$(SOC)/lib$(SOC).a
    endif
    LIBS += lib_$(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/usb/libusb.a
    LIBS += drivers/sk98lin/libsk98lin.a
    LIBS += common/libcommon.a
    LIBS += $(BOARDLIBS)
    
    LIBS := $(addprefix $(obj),$(LIBS))
    .PHONY : $(LIBS)
    
  • 目标all

    ALL = $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map $(U_BOOT_NAND)
    
    all:		$(ALL)
    
    $(obj)u-boot.bin:	$(obj)u-boot
    		$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@
    		
    $(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
    

链接入口

UNDEF_SYM=`arm-linux-objdump -x lib_generic/libgeneric.a board/100ask24x0/lib100ask24x0.a cpu/arm920t/libarm920t.a cpu/arm920t/s3c24x0/libs3c24x0.a lib_arm/libarm.a fs/cramfs/libcramfs.a fs/fat/libfat.a fs/fdos/libfdos.a fs/jffs2/libjffs2.a fs/reiserfs/libreiserfs.a fs/ext2/libext2fs.a net/libnet.a disk/libdisk.a rtc/librtc.a dtt/libdtt.a drivers/libdrivers.a drivers/nand/libnand.a drivers/nand_legacy/libnand_legacy.a drivers/usb/libusb.a drivers/sk98lin/libsk98lin.a common/libcommon.a |sed  -n -e 's/.*\(__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\

cd /home/book/Desktop/u-boot/u-boot-1.1.6 && 
	
arm-linux-ld -Bstatic -T /home/book/Desktop/u-boot/u-boot-1.1.6/board/100ask24x0/u-boot.lds -Ttext 0x33F80000  $UNDEF_SYM cpu/arm920t/start.o \
		--start-group lib_generic/libgeneric.a board/100ask24x0/lib100ask24x0.a cpu/arm920t/libarm920t.a cpu/arm920t/s3c24x0/libs3c24x0.a lib_arm/libarm.a fs/cramfs/libcramfs.a fs/fat/libfat.a fs/fdos/libfdos.a fs/jffs2/libjffs2.a fs/reiserfs/libreiserfs.a fs/ext2/libext2fs.a net/libnet.a disk/libdisk.a rtc/librtc.a dtt/libdtt.a drivers/libdrivers.a drivers/nand/libnand.a drivers/nand_legacy/libnand_legacy.a drivers/usb/libusb.a drivers/sk98lin/libsk98lin.a common/libcommon.a --end-group -L /opt/gcc-3.4.5-glibc-2.3.6/bin/../lib/gcc/arm-linux/3.4.5 -lgcc \
		-Map u-boot.map -o u-boot
arm-linux-objcopy --gap-fill=0xff -O srec u-boot u-boot.srec
arm-linux-objcopy --gap-fill=0xff -O binary u-boot u-boot.bin

  • 查看下最后的链接,可以看到链接脚本是board/100ask24x0/u-boot.lds,代码段的基地址0x33F80000,也就是说,链接脚本里面的地址会加上这个数字.

    arm-linux-ld -Bstatic -T /home/book/Desktop/u-boot/u-boot-1.1.6/board/100ask24x0/u-boot.lds -Ttext 0x33F80000  $UNDEF_SYM cpu/arm920t/start.o \..................
    

    也就是说该u-boot应该在0x33F80000这个位置运行

配置链接地址

  • 搜索下0x33F80000,在board/100ask24x0/config.mk中有定义TEXT_BASE = 0x33F80000

  • 链接参数由makefile中可以看出来$(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS)是在LDFLAGS中定义,我们可以用debug.mk调试,可以使用d-再一层解析具体的,但是这里已经能够看到 $(TEXT_BASE)定义了这个地址了

    make -f Makefile  -f debug.mk  d-LDFLAGS
    
    LDFLAGS=-Bstatic -T /home/book/Desktop/u-boot/u-boot-1.1.6/board/100ask24x0/u-boot.lds -Ttext 0x33F80000 
      origin = file
       value = -Bstatic -T $(LDSCRIPT) -Ttext $(TEXT_BASE) $(PLATFORM_LDFLAGS)
      flavor = recursive
    
  • 也可以搜索下grep "LDFLAGS" * -nR,可以发现在顶层的config.mk看到定义

    LDFLAGS += -Bstatic -T $(LDSCRIPT) -Ttext $(TEXT_BASE) $(PLATFORM_LDFLAGS)
    

附录

附录A:mkconfig解析

###################################################################################
#                                                                                 #
#        首先是进行单板的配置                                                       #
#        make 100ask24x0_config                                                   #
#                                                                                 #
###################################################################################
100ask24x0_config	:	unconfig
	@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0

##################################################################################
#unconfig 执行的操作如下,可以先不去管它
unconfig:
	@rm -f $(obj)include/config.h $(obj)include/config.mk \
		$(obj)board/*/config.tmp $(obj)board/*/*/config.tmp

##################################################################################
#当前目录
SRCTREE		:= $(CURDIR)
# 当前目录下的mkconfig文件
MKCONFIG	:= $(SRCTREE)/mkconfig
export MKCONFIG
##################################################################################
# $@表示目标,在$()中的@也表示目标,接下去的是字符串替换,也就是将目标中的_config 替换为空
# 开头@ 表示不回显
@$(MKCONFIG) $(@:_config=) arm arm920t 100ask24x0 NULL s3c24x0
#也就是相当于  
mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0
# 也就是调用外部shell脚本了


###################################################################################
#                                                                                 #
#        mkconfig的文件注释,shell脚本调用                                          #
#        mkconfig 100ask24x0 arm arm920t 100ask24x0 NULL s3c24x0                  #
#		 [0]		[1]		 [2] 	[3]		[4]		[5]		[6]                   #
###################################################################################
#!/bin/sh -e

# Script to create header files and links to configure
# U-Boot for a specific board.
#
# Parameters:  Target  Architecture  CPU  Board [VENDOR] [SOC]
#
# (C) 2002-2006 DENX Software Engineering, Wolfgang Denk <wd@denx.de>
#

APPEND=no	# Default: Create new config file
BOARD_NAME=""	# Name to print in make output

# 不包含这些打头的参数,忽略这段代码
# $# 参数个数,-gt 大于
while [ $# -gt 0 ] ; do
	case "$1" in
	--) shift ; break ;;
	-a) shift ; APPEND=yes ;;
	-n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;
	*)  break ;;
	esac
done

# 利用了||的特性,如果未定义BOARD_NAME,BOARD_NAME=参数1=100ask24x0
[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

# 参数个数合法性判断,必须是5个
[ $# -lt 4 ] && exit 1
[ $# -gt 6 ] && exit 1

# 打印显示
echo "Configuring for ${BOARD_NAME} board..."

#
# Create link to architecture specific headers
#

# 这里SRCTREE=OBJTREE=$(CURDIR),我们可以去顶层的makefile中看到
# 也可以使用debug打印变量 make -f Makefile  -f debug.mk  OBJTREE
# OBJTREE		:= $(if $(BUILD_DIR),$(BUILD_DIR),$(CURDIR))
# SRCTREE		:= $(CURDIR)
# 也就是说 执行else 分支
# 建立asm的符号连接
if [ "$SRCTREE" != "$OBJTREE" ] ; then
	mkdir -p ${OBJTREE}/include
	mkdir -p ${OBJTREE}/include2
	cd ${OBJTREE}/include2
	rm -f asm
	ln -s ${SRCTREE}/include/asm-$2 asm
	LNPREFIX="../../include2/asm/"
	cd ../include
	rm -rf asm-$2
	rm -f asm
	mkdir asm-$2
	ln -s asm-$2 asm
else
	# 删除原有的asm链接,建立新的链接 ln -s asm-arm asm
	cd ./include
	rm -f asm
	ln -s asm-$2 asm
fi

rm -f asm-$2/arch

# -z string 测试指定字符是否为空,空着真,非空为假
# -o: or
# $6=s3c24x0,执行else
# ln -s arch-s3c24x0 asm-arm/arch
# asm-arch指向了arch-s3c24x0

if [ -z "$6" -o "$6" = "NULL" ] ; then
	ln -s ${LNPREFIX}arch-$3 asm-$2/arch
else
	ln -s ${LNPREFIX}arch-$6 asm-$2/arch
fi


# if满足,删除 asm-arm/proc
# 重新建立新的链接 proc-armc 到asm-arm/proc
if [ "$2" = "arm" ] ; then
	rm -f asm-$2/proc
	ln -s ${LNPREFIX}proc-armv asm-$2/proc
fi

#
# Create include file for Make
#
# ARCH   = arm
# CPU    = arm920t
# BOARD  = 100ask24x0
# SOC    = s3c24x0
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

#
# Create board specific header file
# 
# /* Automatically generated - do not edit */
# #include <configs/100ask24x0.h>

if [ "$APPEND" = "yes" ]	# Append to existing config file
then
	echo >> 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

exit 0

附录B 链接脚本

OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
/*OUTPUT_FORMAT("elf32-arm", "elf32-arm", "elf32-arm")*/
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
	. = 0x00000000;     //这个地址会加上 -Ttext 0x33F80000 这个地址

	. = ALIGN(4);
	.text      :
	{
        //代码段的第一个文件是这个
	  cpu/arm920t/start.o	(.text)
          board/100ask24x0/boot_init.o (.text)
       //其他所有代码段   
	  *(.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);
	__bss_start = .;
	.bss : { *(.bss) }
	_end = .;
}
posted @ 2018-11-26 22:57  zongzi10010  阅读(276)  评论(0编辑  收藏  举报