u-boot(二)makefile

时间：2018-11-27 00:42:22 收藏：0 阅读：182

u-boot(二)makefile

title: u-boot(二)makefile
tags: linux
date: 2018-09-22 20:56:05
---

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

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
```
/* 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:

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
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 = .;
}

原文：https://www.cnblogs.com/zongzi10010/p/10023667.html