u-boot-2014.10移植第6天----深入分析代码（一）

硬件平台：tq2440

开发环境：Ubuntu-3.11

u-boot版本：2014.10

本文允许转载，请注明出处：http://blog.csdn.net/fulinus

前面我们看到了一个lds文件，我们这里深入的了解一下：

section.c：

/*
 * Copyright: (C) 2014 EAST fulinux <[email protected]>
 */
#include <stdio.h>
#include <stdlib.h>

int localmemory0 __attribute__((section("LOCALmem"))) = 0;
int localmemory1 __attribute__((section("LOCALmem"))) = 0;
int globalmemory __attribute__((section("GLOBALmem"))) = 0;

int main (int argc, char *argv[])
{
    localmemory0 = 0x456;
    localmemory1 = 0x123;

    globalmemory = localmemory0 + localmemory1;

    return 0;
}

$ gcc -c -o section.o section.c

$ objdump -d section.o 

section.o：     文件格式 elf64-x86-64

Disassembly of section .text:

0000000000000000 <main>:
   0:   55                      push   %rbp
   1:   48 89 e5                mov    %rsp,%rbp
   4:   89 7d fc                mov    %edi,-0x4(%rbp)
   7:   48 89 75 f0             mov    %rsi,-0x10(%rbp)
   b:   c7 05 00 00 00 00 56    movl   $0x456,0x0(%rip)        # 15 <main+0x15>
  12:   04 00 00
  15:   c7 05 00 00 00 00 23    movl   $0x123,0x0(%rip)        # 1f <main+0x1f>
  1c:   01 00 00
  1f:   8b 15 00 00 00 00       mov    0x0(%rip),%edx        # 25 <main+0x25>
  25:   8b 05 00 00 00 00       mov    0x0(%rip),%eax        # 2b <main+0x2b>
  2b:   01 d0                   add    %edx,%eax
  2d:   89 05 00 00 00 00       mov    %eax,0x0(%rip)        # 33 <main+0x33>
  33:   b8 00 00 00 00          mov    $0x0,%eax
  38:   5d                      pop    %rbp
  39:   c3                      retq 

section.lds:

SECTIONS
{
    .text :
    {
        *(.text)
    }
    LOCALmem 0x1f0000 :
    {
        *(LOCALmem)
    }
    GLOBALmem 0xff0000 :
    {
        *(GLOBALmem)
    }
}

$ ld -o section.elf -T section.lds section.o

$ objdump -S section.elf 

section.elf：     文件格式 elf64-x86-64

Disassembly of section .text:

0000000000000000 <main>:
   0:   55                      push   %rbp
   1:   48 89 e5                mov    %rsp,%rbp
   4:   89 7d fc                mov    %edi,-0x4(%rbp)
   7:   48 89 75 f0             mov    %rsi,-0x10(%rbp)
   b:   c7 05 eb ff 1e 00 56    movl   $0x456,0x1effeb(%rip)        # 1f0000 <localmemory0>
  12:   04 00 00
  15:   c7 05 e5 ff 1e 00 23    movl   $0x123,0x1effe5(%rip)        # 1f0004 <localmemory1>
  1c:   01 00 00
  1f:   8b 15 db ff 1e 00       mov    0x1effdb(%rip),%edx        # 1f0000 <localmemory0>
  25:   8b 05 d9 ff 1e 00       mov    0x1effd9(%rip),%eax        # 1f0004 <localmemory1>
  2b:   01 d0                   add    %edx,%eax
  2d:   89 05 cd ff fe 00       mov    %eax,0xfeffcd(%rip)        # ff0000 <globalmemory>
  33:   b8 00 00 00 00          mov    $0x0,%eax
  38:   5d                      pop    %rbp
  39:   c3                      retq
[[email protected] jupiter]$