arm9_uboot_Makefile结构分析

Posted 2020-11-13 lzd626

1.解压缩

tar xjf u-boot-1.1.6.tar.bz2

2.打补丁

patch -p1 < ../u-boot-1.1.6_jz2440.patch

3.配置

make 100ask24x0_config，下面为Makefile

MKCONFIG    := $(SRCTREE)/mkconfig

unconfig:　　　　　　#清楚配置信息

    @rm -f $(obj)include/config.h $(obj)include/config.mk 

        $(obj)board/*/config.tmp $(obj)board/*/*/config.tmp

 

100ask24x0_config   :   unconfig

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

#上面这段翻译为：mkconfig 100ask24x0  arm arm920t 100ask24x0 NULL s3c24x0

make 100ask24x0_config这个命令执行的就是 mkconfig 100ask24x0  arm arm920t 100ask24x0 NULL s3c24x0这个脚本，下面我们看下mkconfig文件

#!/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 <[e-mail]>

#

APPEND=no   # Default: Create new config file

BOARD_NAME=""   # Name to print in make output

# mkconfig 100ask24x0  arm arm920t 100ask24x0 NULL s3c24x0

# $0         $1         $2   $3      $4       $5     $6

[ "${BOARD_NAME}" ] || BOARD_NAME="$1"

[ $# -lt 4 ] && exit 1

[ $# -gt 6 ] && exit 1

echo "Configuring for ${BOARD_NAME} board..."

#

# Create link to architecture specific headers

#

    cd ./include

    rm -f asm

    ln -s asm-$2 asm  #ln -s asm-arm asm 创建链接文件，以指定特定架构

rm -f asm-$2/arch

ln -s ${LNPREFIX}arch-$6 asm-$2/arch   #ln -s arch-s3c24x0 asm-arm/arch

if [ "$2" = "arm" ] ; then

    rm -f asm-$2/proc

    ln -s ${LNPREFIX}proc-armv asm-$2/proc  #ln -s proc-armv asm-arm/proc

fi

#

# Create include file for Make

#

echo "ARCH   = $2" >  config.mk  #新建

echo "CPU    = $3" >> config.mk  #添加

echo "BOARD  = $4" >> config.mk  #添加

[ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk  #NULL

[ "$6" ] && [ "$6" != "NULL" ] && echo "SOC    = $6" >> config.mk  #添加

#

# Create board specific header file

#

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

then

    echo >> config.h  

else

    > config.h      # 新建

fi

echo "/* Automatically generated - do not edit */" >>config.h

echo "#include <configs/$1.h>" >>config.h

exit 0

mkconfig新建的文件打印内容如下：

 

 

4.编译

make

继续提取Makefile一些主要成分:

# load ARCH, BOARD, and CPU configuration
include $(OBJTREE)/include/config.mk

ifeq ($(ARCH),arm)
CROSS_COMPILE = arm-linux-

# U-Boot objects....order is important (i.e. start must be first)
OBJS  = cpu/$(CPU)/start.o

LIBS  = lib_generic/libgeneric.a
LIBS += board/$(BOARDDIR)/lib$(BOARD).a
LIBS += cpu/$(CPU)/lib$(CPU).a

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_.*)/-u1/p‘|sort|uniq`;

        cd $(LNDIR) && $(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS) 

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

            -Map u-boot.map -o u-boot

# LDFLAGS在根目录config.mk中： LDFLAGS += -Bstatic -T $(LDSCRIPT) -Ttext $(TEXT_BASE) $(PLATFORM_LDFLAGS)

  # TEXT_BASE在board/100ask24x0/config.mk中： TEXT_BASE = 0x33F80000

再看一下u-boot.lds

/*
 * (C) Copyright 2002
 * Gary Jennejohn, DENX Software Engineering, <[e-mail]>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
/*OUTPUT_FORMAT("elf32-arm", "elf32-arm", "elf32-arm")*/
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
    . = 0x00000000; //0x33F80000这个地址是0x30000000+64M-512Kb所在位置，当uboot大于512就要修改这个地址

    . = ALIGN(4);
    .text      :
    {
      cpu/arm920t/start.o    (.text)
          board/100ask24x0/boot_init.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);
    __bss_start = .;
    .bss : { *(.bss) }
    _end = .;
}