一、什么是Map文件
map文件就是通过编译器编译之后，生成的程序、数据及IO空间信息的一种映射文件，里面包含函数大小，入口地址等一些重要信息。从map文件我们可以了解到：
- 程序各区段的寻址是否正确
- 程序各区段的size，即目前存储器的使用量
- 程序中各个symbol的地址
- 各个symbol在存储器中的顺序关系（这在调试时很有用）
- 各个程序文件的存储用量
二、实例说明
1.简单的C 程序，生成map 文件
main.c
#include <stdio.h>
#include "add.h"
char* Hello="HelloWorld!";
char array[4]={0,1,2,3};
char array0[6];
int g_gloableInt;
double doubletest = 10;
char* testP = NULL;
int* pInt;
#define READ_SIZE (0x7A0)
void main(void)
{
int a = 5,b = 6,sum=0;
static int staticInt = 0;
char data[READ_SIZE]={0};
int ret = 0;
FILE* fp = fopen("abuf_apu_nbsm_o1_1_00720.mpg","r");
//FILE* fp_out = fopen("abuf_apu_nbsm_o1_1_00720_out.mpg","w+");
FILE* fp_out = fopen("abuf_apu_nbsm_o1_1_00720_out.mpg","w+");
if(!fp || !fp_out)
{
printf("NULL data file!");
return;
}
sum=math(a,b);
printf("sum is %d\n",sum);
staticInt += sum;
g_gloableInt =0;
printf("main=%016llx,math=%016llx,add=%016llx,sub=%016llx\ng_gloableInt=%016llx staticInt=%016llx Hello=%016llx\n",(long long)main,(long long)math,(long long)add,(long long)sub,(long long)&g_gloableInt,(long long)&staticInt,(long long)Hello);
printf("sizeof(doubletest)=%ld sizeof(testP)=%ld sizeof(array0)=%ld \n",sizeof(doubletest),sizeof(testP),sizeof(array0));
printf("&doubletest=%016llx,testP=%016llx array0=%016llx\n",(long long)&doubletest,(long long)testP,(long long)array0);
fseek(fp, 0, SEEK_SET);
fseek(fp_out, 0, SEEK_SET);
do
{
ret=fread(data,1,READ_SIZE,fp);
//printf("read %d byte data\n",ret);
fwrite((data+32),(ret-32),1,fp_out);
}while(ret==READ_SIZE);
fclose(fp);
fclose(fp_out);
return;
}
---------------------------------------------------------------------------------------
add.c
#include "add.h"
int Min = 10;
int sub(int* v)
{
*v = (*v >Min)? (*v - Min):*v ;
return 0;
}
int add(int a, int b)
{
int sum = a+b;
sub(&sum);
return sum;
}
int math(int a,int b)
{
return add(a,b);
}
---------------------------------------------------------------------------------------
#ifndef __ADD_H__
#define __ADD_H__
int math(int a, int b);
int add(int a, int b);
int sub(int* a);
#endif
--------------------------------------------------------------------------------------
dummy.c
#include "dummy.h"
int dummy_ver0(int dummmy)
{
return 0;
}
--------------------------------------------------------------------------------------
#ifndef __DUMMY_H__
#define __DUMMY_H__
int dummy_ver0(int dummmy);
#endif编译命令
gcc main.c add.c -Wl,-Map,add.map -o main
生成的map 文件为：
Archive member included to satisfy reference by file (symbol) ==>included archive
/usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o (__libc_csu_init)
As-needed library included to satisfy reference by file (symbol) ==>link 的lib
libc.so.6 /tmp/ccYQAtfU.o (fopen@@GLIBC_2.2.5)
Allocating common symbols
Common symbol size file
pInt 0x8 /tmp/ccYQAtfU.o
g_gloableInt 0x4 /tmp/ccYQAtfU.o
array0 0x6 /tmp/ccYQAtfU.o
Discarded input sections
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccYQAtfU.o ==>实际是main.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccetcq5K.o ==>实际是add.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccYNVa0B.o ==>实际是dummy.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
Memory Configuration
Name Origin Length Attributes
*default* 0x0000000000000000 0xffffffffffffffff
Linker script and memory map
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
LOAD /tmp/ccYQAtfU.o
LOAD /tmp/ccetcq5K.o
LOAD /tmp/ccYNVa0B.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so
START GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so.1
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
END GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/libc.so
START GROUP
LOAD /lib/x86_64-linux-gnu/libc.so.6
LOAD /usr/lib/x86_64-linux-gnu/libc_nonshared.a
LOAD /lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
END GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so
START GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so.1
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
END GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
[!provide] PROVIDE (__executable_start = SEGMENT_START ("text-segment", 0x0))
0x0000000000000238 . = (SEGMENT_START ("text-segment", 0x0) + SIZEOF_HEADERS)
.interp 0x0000000000000238 0x1c
*(.interp)
.interp 0x0000000000000238 0x1c /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.note.ABI-tag 0x0000000000000254 0x20
.note.ABI-tag 0x0000000000000254 0x20 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.note.gnu.build-id
0x0000000000000274 0x24
*(.note.gnu.build-id)
.note.gnu.build-id
0x0000000000000274 0x24 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.hash
*(.hash)
.gnu.hash 0x0000000000000298 0x1c
*(.gnu.hash)
.gnu.hash 0x0000000000000298 0x1c /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.dynsym 0x00000000000002b8 0x138
*(.dynsym)
.dynsym 0x00000000000002b8 0x138 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.dynstr 0x00000000000003f0 0xbf
*(.dynstr)
.dynstr 0x00000000000003f0 0xbf /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.gnu.version 0x00000000000004b0 0x1a
*(.gnu.version)
.gnu.version 0x00000000000004b0 0x1a /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.gnu.version_d 0x00000000000004d0 0x0
*(.gnu.version_d)
.gnu.version_d
0x00000000000004d0 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.gnu.version_r 0x00000000000004d0 0x30
*(.gnu.version_r)
.gnu.version_r
0x00000000000004d0 0x30 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.rela.dyn 0x0000000000000500 0xd8
*(.rela.init)
*(.rela.text .rela.text.* .rela.gnu.linkonce.t.*)
.rela.text 0x0000000000000500 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.rela.fini)
*(.rela.rodata .rela.rodata.* .rela.gnu.linkonce.r.*)
*(.rela.data .rela.data.* .rela.gnu.linkonce.d.*)
.rela.data.rel.ro
0x0000000000000500 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.rela.data.rel.local
0x0000000000000500 0x30 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.rela.tdata .rela.tdata.* .rela.gnu.linkonce.td.*)
*(.rela.tbss .rela.tbss.* .rela.gnu.linkonce.tb.*)
*(.rela.ctors)
*(.rela.dtors)
*(.rela.got)
.rela.got 0x0000000000000530 0x78 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.rela.bss .rela.bss.* .rela.gnu.linkonce.b.*)
.rela.bss 0x00000000000005a8 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.rela.ldata .rela.ldata.* .rela.gnu.linkonce.l.*)
*(.rela.lbss .rela.lbss.* .rela.gnu.linkonce.lb.*)
*(.rela.lrodata .rela.lrodata.* .rela.gnu.linkonce.lr.*)
*(.rela.ifunc)
.rela.ifunc 0x00000000000005a8 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.rela.fini_array
0x00000000000005a8 0x18 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.rela.init_array
0x00000000000005c0 0x18 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.rela.plt 0x00000000000005d8 0xa8
*(.rela.plt)
.rela.plt 0x00000000000005d8 0xa8 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
[!provide] PROVIDE (__rela_iplt_start = .)
*(.rela.iplt)
[!provide] PROVIDE (__rela_iplt_end = .)
.init 0x0000000000000680 0x17
*(SORT_NONE(.init))
.init 0x0000000000000680 0x12 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
0x0000000000000680 _init
.init 0x0000000000000692 0x5 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
.plt 0x00000000000006a0 0x80
*(.plt)
.plt 0x00000000000006a0 0x80 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.iplt)
.plt.got 0x0000000000000720 0x8
*(.plt.got)
.plt.got 0x0000000000000720 0x8 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.plt.sec
*(.plt.sec)
.text 0x0000000000000730 0x4c2
*(.text.unlikely .text.*_unlikely .text.unlikely.*)
*(.text.exit .text.exit.*)
*(.text.startup .text.startup.*)
*(.text.hot .text.hot.*)
*(.text .stub .text.* .gnu.linkonce.t.*)
.text 0x0000000000000730 0x2b /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000730 _start
.text 0x000000000000075b 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
*fill* 0x000000000000075b 0x5
.text 0x0000000000000760 0xda /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
.text 0x000000000000083a 0x289 /tmp/ccYQAtfU.o
0x000000000000083a main
.text 0x0000000000000ac3 0xa9 /tmp/ccetcq5K.o
0x0000000000000ac3 sub
0x0000000000000b00 add
0x0000000000000b4d math
.text 0x0000000000000b6c 0xe /tmp/ccYNVa0B.o
0x0000000000000b6c dummy_ver0
*fill* 0x0000000000000b7a 0x6
.text 0x0000000000000b80 0x72 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
0x0000000000000b80 __libc_csu_init
0x0000000000000bf0 __libc_csu_fini
.text 0x0000000000000bf2 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.text 0x0000000000000bf2 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
*(.gnu.warning)
.fini 0x0000000000000bf4 0x9
*(SORT_NONE(.fini))
.fini 0x0000000000000bf4 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
0x0000000000000bf4 _fini
.fini 0x0000000000000bf8 0x5 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
[!provide] PROVIDE (__etext = .)
[!provide] PROVIDE (_etext = .)
[!provide] PROVIDE (etext = .)
.rodata 0x0000000000000c00 0x152
*(.rodata .rodata.* .gnu.linkonce.r.*)
.rodata.cst4 0x0000000000000c00 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000c00 _IO_stdin_used
*fill* 0x0000000000000c04 0x4
.rodata 0x0000000000000c08 0x14a /tmp/ccYQAtfU.o
.rodata1
*(.rodata1)
.eh_frame_hdr 0x0000000000000d54 0x5c
*(.eh_frame_hdr)
.eh_frame_hdr 0x0000000000000d54 0x5c /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000d54 __GNU_EH_FRAME_HDR
*(.eh_frame_entry .eh_frame_entry.*)
.eh_frame 0x0000000000000db0 0x188
*(.eh_frame)
.eh_frame 0x0000000000000db0 0x30 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x2c (size before relaxing)
*fill* 0x0000000000000de0 0x0
.eh_frame 0x0000000000000de0 0x40 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.eh_frame 0x0000000000000e20 0x18 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x30 (size before relaxing)
.eh_frame 0x0000000000000e38 0x20 /tmp/ccYQAtfU.o
0x38 (size before relaxing)
.eh_frame 0x0000000000000e58 0x60 /tmp/ccetcq5K.o
0x78 (size before relaxing)
.eh_frame 0x0000000000000eb8 0x20 /tmp/ccYNVa0B.o
0x38 (size before relaxing)
.eh_frame 0x0000000000000ed8 0x5c /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
0x78 (size before relaxing)
.eh_frame 0x0000000000000f34 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
*(.eh_frame.*)
.gcc_except_table
*(.gcc_except_table .gcc_except_table.*)
.gnu_extab
*(.gnu_extab*)
.exception_ranges
*(.exception_ranges .exception_ranges*)
0x0000000000201d88 . = DATA_SEGMENT_ALIGN (CONSTANT (MAXPAGESIZE), CONSTANT (COMMONPAGESIZE))
.eh_frame
*(.eh_frame)
*(.eh_frame.*)
.gnu_extab
*(.gnu_extab)
.gcc_except_table
*(.gcc_except_table .gcc_except_table.*)
.exception_ranges
*(.exception_ranges .exception_ranges*)
.tdata
*(.tdata .tdata.* .gnu.linkonce.td.*)
.tbss
*(.tbss .tbss.* .gnu.linkonce.tb.*)
*(.tcommon)
.preinit_array 0x0000000000201d88 0x0
[!provide] PROVIDE (__preinit_array_start = .)
*(.preinit_array)
[!provide] PROVIDE (__preinit_array_end = .)
.init_array 0x0000000000201d88 0x8
0x0000000000201d88 PROVIDE (__init_array_start = .)
*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*))
*(.init_array EXCLUDE_FILE(*crtend?.o *crtend.o *crtbegin?.o *crtbegin.o) .ctors)
.init_array 0x0000000000201d88 0x8 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
0x0000000000201d90 PROVIDE (__init_array_end = .)
.fini_array 0x0000000000201d90 0x8
[!provide] PROVIDE (__fini_array_start = .)
*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*))
*(.fini_array EXCLUDE_FILE(*crtend?.o *crtend.o *crtbegin?.o *crtbegin.o) .dtors)
.fini_array 0x0000000000201d90 0x8 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
[!provide] PROVIDE (__fini_array_end = .)
.ctors
*crtbegin.o(.ctors)
*crtbegin?.o(.ctors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)
*(SORT_BY_NAME(.ctors.*))
*(.ctors)
.dtors
*crtbegin.o(.dtors)
*crtbegin?.o(.dtors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)
*(SORT_BY_NAME(.dtors.*))
*(.dtors)
.jcr
*(.jcr)
.data.rel.ro 0x0000000000201d98 0x0
*(.data.rel.ro.local* .gnu.linkonce.d.rel.ro.local.*)
*(.data.rel.ro .data.rel.ro.* .gnu.linkonce.d.rel.ro.*)
.data.rel.ro 0x0000000000201d98 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.dynamic 0x0000000000201d98 0x1f0
*(.dynamic)
.dynamic 0x0000000000201d98 0x1f0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000201d98 _DYNAMIC
.got 0x0000000000201f88 0x78
*(.got.plt)
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0x0000000000201f88 _GLOBAL_OFFSET_TABLE_
*(.igot.plt)
*(.got)
.got 0x0000000000201fd8 0x28 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.igot)
0x0000000000202000 . = DATA_SEGMENT_RELRO_END (., 0x0)
.data 0x0000000000202000 0x2c
*(.data .data.* .gnu.linkonce.d.*)
.data 0x0000000000202000 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
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0x0000000000202000 __data_start
.data 0x0000000000202004 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.data 0x0000000000202004 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
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.data.rel.local
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0x0000000000202008 __dso_handle
.data 0x0000000000202010 0x10 /tmp/ccYQAtfU.o
0x0000000000202010 array
0x0000000000202018 doubletest
.data.rel.local
0x0000000000202020 0x8 /tmp/ccYQAtfU.o
0x0000000000202020 Hello
.data 0x0000000000202028 0x4 /tmp/ccetcq5K.o
0x0000000000202028 Min
.data 0x000000000020202c 0x0 /tmp/ccYNVa0B.o
.data 0x000000000020202c 0x0 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
.data 0x000000000020202c 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.data 0x000000000020202c 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
.tm_clone_table
0x0000000000202030 0x0
.tm_clone_table
0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
.tm_clone_table
0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.data1
*(.data1)
0x0000000000202030 _edata = .
[!provide] PROVIDE (edata = .)
0x0000000000202030 . = .
0x0000000000202030 __bss_start = .
.bss 0x0000000000202030 0x30
*(.dynbss)
.dynbss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.bss .bss.* .gnu.linkonce.b.*)
.bss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.bss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.bss 0x0000000000202030 0x1 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
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0x0000000000202038 testP
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.bss 0x0000000000202044 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
*(COMMON)
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0x0000000000202048 pInt
0x0000000000202050 g_gloableInt
0x0000000000202054 array0
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*fill* 0x000000000020205a 0x6
.lbss
*(.dynlbss)
*(.lbss .lbss.* .gnu.linkonce.lb.*)
*(LARGE_COMMON)
0x0000000000202060 . = ALIGN (0x8)
0x0000000000202060 . = SEGMENT_START ("ldata-segment", .)
.lrodata
*(.lrodata .lrodata.* .gnu.linkonce.lr.*)
.ldata 0x0000000000602060 0x0
*(.ldata .ldata.* .gnu.linkonce.l.*)
0x0000000000602060 . = ALIGN ((. != 0x0)?0x8:0x1)
0x0000000000602060 . = ALIGN (0x8)
0x0000000000602060 _end = .
[!provide] PROVIDE (end = .)
0x0000000000602060 . = DATA_SEGMENT_END (.)
.stab
*(.stab)
.stabstr
*(.stabstr)
.stab.excl
*(.stab.excl)
.stab.exclstr
*(.stab.exclstr)
.stab.index
*(.stab.index)
.stab.indexstr
*(.stab.indexstr)
.comment 0x0000000000000000 0x29
*(.comment)
.comment 0x0000000000000000 0x29 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
0x2a (size before relaxing)
.comment 0x0000000000000029 0x2a /tmp/ccYQAtfU.o
.comment 0x0000000000000029 0x2a /tmp/ccetcq5K.o
.comment 0x0000000000000029 0x2a /tmp/ccYNVa0B.o
.comment 0x0000000000000029 0x2a /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.debug
*(.debug)
.line
*(.line)
.debug_srcinfo
*(.debug_srcinfo)
.debug_sfnames
*(.debug_sfnames)
.debug_aranges
*(.debug_aranges)
.debug_pubnames
*(.debug_pubnames)
.debug_info
*(.debug_info .gnu.linkonce.wi.*)
.debug_abbrev
*(.debug_abbrev)
.debug_line
*(.debug_line .debug_line.* .debug_line_end)
.debug_frame
*(.debug_frame)
.debug_str
*(.debug_str)
.debug_loc
*(.debug_loc)
.debug_macinfo
*(.debug_macinfo)
.debug_weaknames
*(.debug_weaknames)
.debug_funcnames
*(.debug_funcnames)
.debug_typenames
*(.debug_typenames)
.debug_varnames
*(.debug_varnames)
.debug_pubtypes
*(.debug_pubtypes)
.debug_ranges
*(.debug_ranges)
.debug_macro
*(.debug_macro)
.debug_addr
*(.debug_addr)
.gnu.attributes
*(.gnu.attributes)
/DISCARD/
*(.note.GNU-stack)
*(.gnu_debuglink)
*(.gnu.lto_*)
OUTPUT(main elf64-x86-64)2.对比C 程序，读map 文件
tmp/testC$ ./main
sum is 1
main=000055854636e83a,math=000055854636eb4d,add=000055854636eb00,sub=000055854636eac3
g_gloableInt=0000558546570050 staticInt=0000558546570040 Hello=000055854636ec08
sizeof(doubletest)=8 sizeof(testP)=8 sizeof(array0)=6
&doubletest=0000558546570018,testP=0000000000000000 array0=0000558546570054
1）首先是included archive file
Archive member included to satisfy reference by file (symbol) ==>included archive
/usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o (__libc_csu_init)解析：
> Scrt1.o 这个目标文件会调用到__libc_csu_init 这个函数
> __libc_csu_init 这个函数在elf-init.oS 目标文件中
> elf-init.oS 目标文件 被打包在libc_nonshared.a 这个archive file
2)然后是library included
As-needed library included to satisfy reference by file (symbol) ==>link 的lib
libc.so.6 /tmp/ccYQAtfU.o (fopen@@GLIBC_2.2.5)
解析：
> /tmp/ccYQAtfU.o（实际是main.0） 这个目标文件会调用到fopen 这个函数
> fopen这个函数在libc.so.6 这个lib 中
3)然后是common symbols
Allocating common symbols
Common symbol size filepInt 0x8 /tmp/ccYQAtfU.o
g_gloableInt 0x4 /tmp/ccYQAtfU.o
array0 0x6 /tmp/ccYQAtfU.o解析：
> /tmp/ccYQAtfU.o（实际是main.0）
> 上述3个变量都是main.c 文件中定义的全局变量，并且没有初始化
> 上述3个全局变量，可以被任何module 访问到，使用并且改变
> 实际写程序中，可以通过common symbols 列出的变量，来检查是否有必要写全局变量，如没有必要，则改成static.
4)Discarded input sections
Discarded input sections
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccYQAtfU.o ==>实际是main.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccetcq5K.o ==>实际是add.o
.note.GNU-stack
0x0000000000000000 0x0 /tmp/ccYNVa0B.o ==>实际是dummy.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.note.GNU-stack
0x0000000000000000 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o解析：
> 原本以为测试程序dummy.c 这个文件中的function 没有被引用，只会把dummy.o 放在discarded input sections
> 实际测试结果，add.o （所有function和变量都被引用）也被放在了这里，有些不理解
5)Memory Configuration
Memory Configuration
Name Origin Length Attributes
*default* 0x0000000000000000 0xffffffffffffffff解析：
> 因为我是在linux pc 上编译，因此这部分没有特殊的memory 限制
6）Linker script and memory map
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
LOAD /tmp/ccYQAtfU.o
LOAD /tmp/ccetcq5K.o
LOAD /tmp/ccYNVa0B.o
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so
START GROUP
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc_s.so.1
LOAD /usr/lib/gcc/x86_64-linux-gnu/7/libgcc.a
END GROUP......
(.text start address is 0x0000000000000730, total size is x4c2)
.text 0x0000000000000730 0x4c2
*(.text.unlikely .text.*_unlikely .text.unlikely.*)
*(.text.exit .text.exit.*)
*(.text.startup .text.startup.*)
*(.text.hot .text.hot.*)
*(.text .stub .text.* .gnu.linkonce.t.*)
.text 0x0000000000000730 0x2b /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000730 _start
.text 0x000000000000075b 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
*fill* 0x000000000000075b 0x5
.text 0x0000000000000760 0xda /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o(这里根据函数的调用关系，依次排列函数在memory 中的位置，先执行的先占memory)
.text 0x000000000000083a 0x289 /tmp/ccYQAtfU.o(main.o)
0x000000000000083a main
.text 0x0000000000000ac3 0xa9 /tmp/ccetcq5K.o(add.o)
0x0000000000000ac3 sub(0xb00-0xac3=0x3D 表示sub函数占用的memory,不包含函数的data)
0x0000000000000b00 add
0x0000000000000b4d math
.text 0x0000000000000b6c 0xe /tmp/ccYNVa0B.o(dummy.o)
0x0000000000000b6c dummy_ver0
*fill* 0x0000000000000b7a 0x6
.text 0x0000000000000b80 0x72 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
0x0000000000000b80 __libc_csu_init
0x0000000000000bf0 __libc_csu_fini
.text 0x0000000000000bf2 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.text 0x0000000000000bf2 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
*(.gnu.warning).fini 0x0000000000000bf4 0x9
*(SORT_NONE(.fini))
.fini 0x0000000000000bf4 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
0x0000000000000bf4 _fini
.fini 0x0000000000000bf8 0x5 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
[!provide] PROVIDE (__etext = .)
[!provide] PROVIDE (_etext = .)
[!provide] PROVIDE (etext = .)（这里是read only data 区域，比如程序中的“helloWorld”就放在这里）
（这块区域start address 是0x0000000000000c00，total size is 0x152 ）
.rodata 0x0000000000000c00 0x152
*(.rodata .rodata.* .gnu.linkonce.r.*)
.rodata.cst4 0x0000000000000c00 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000c00 _IO_stdin_used
*fill* 0x0000000000000c04 0x4
.rodata 0x0000000000000c08 0x14a /tmp/ccYQAtfU.o("helloWorld"?).rodata1
*(.rodata1).eh_frame_hdr 0x0000000000000d54 0x5c
*(.eh_frame_hdr)
.eh_frame_hdr 0x0000000000000d54 0x5c /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000000d54 __GNU_EH_FRAME_HDR
*(.eh_frame_entry .eh_frame_entry.*).eh_frame 0x0000000000000db0 0x188
*(.eh_frame)
.eh_frame 0x0000000000000db0 0x30 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x2c (size before relaxing)
*fill* 0x0000000000000de0 0x0
.eh_frame 0x0000000000000de0 0x40 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.eh_frame 0x0000000000000e20 0x18 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x30 (size before relaxing)
.eh_frame 0x0000000000000e38 0x20 /tmp/ccYQAtfU.o
0x38 (size before relaxing)
.eh_frame 0x0000000000000e58 0x60 /tmp/ccetcq5K.o
0x78 (size before relaxing)
.eh_frame 0x0000000000000eb8 0x20 /tmp/ccYNVa0B.o
0x38 (size before relaxing)
.eh_frame 0x0000000000000ed8 0x5c /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
0x78 (size before relaxing)
.eh_frame 0x0000000000000f34 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
*(.eh_frame.*)
6）.data 区域
（start address is 0x0000000000202000,total size is 0x2c）
.data 0x0000000000202000 0x2c
*(.data .data.* .gnu.linkonce.d.*)
.data 0x0000000000202000 0x4 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
0x0000000000202000 data_start
0x0000000000202000 __data_start
.data 0x0000000000202004 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.data 0x0000000000202004 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
*fill* 0x0000000000202004 0x4
.data.rel.local
0x0000000000202008 0x8 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
0x0000000000202008 __dso_handle
.data 0x0000000000202010 0x10 /tmp/ccYQAtfU.o
0x0000000000202010 array(array 占用8byte,说明pointer 占用8byte，64bit 系统)
0x0000000000202018 doubletest（double 类型占用8byte）
.data.rel.local
0x0000000000202020 0x8 /tmp/ccYQAtfU.o(Hello 字符指针占用8byte)
0x0000000000202020 Hello
.data 0x0000000000202028 0x4 /tmp/ccetcq5K.o（int 类型占用4byte）
0x0000000000202028 Min
.data 0x000000000020202c 0x0 /tmp/ccYNVa0B.o(没有全局变量，因此size 是0)
.data 0x000000000020202c 0x0 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
.data 0x000000000020202c 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.data 0x000000000020202c 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
解析：
> 初始化的全局变量，会放在这里
> 未初始化的全局变量，不会放在这里
> 如全局变量初始化为0，有的编译器会优化到.bss 。
6）.bss 区域
（start address is 0x0000000000202030,total size is 0x30）
.bss 0x0000000000202030 0x30
*(.dynbss)
.dynbss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
*(.bss .bss.* .gnu.linkonce.b.*)
.bss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o
.bss 0x0000000000202030 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crti.o
.bss 0x0000000000202030 0x1 /usr/lib/gcc/x86_64-linux-gnu/7/crtbeginS.o
*fill* 0x0000000000202031 0x7
.bss 0x0000000000202038 0xc /tmp/ccYQAtfU.o(bss 中指针占12byte?No)
0x0000000000202038 testP
.bss 0x0000000000202044 0x0 /tmp/ccetcq5K.o
.bss 0x0000000000202044 0x0 /tmp/ccYNVa0B.o
.bss 0x0000000000202044 0x0 /usr/lib/x86_64-linux-gnu/libc_nonshared.a(elf-init.oS)
.bss 0x0000000000202044 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/crtendS.o
.bss 0x0000000000202044 0x0 /usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/crtn.o
*(COMMON)
*fill* 0x0000000000202044 0x4
COMMON 0x0000000000202048 0x12 /tmp/ccYQAtfU.o
0x0000000000202048 pInt(此处指针占8byte)
0x0000000000202050 g_gloableInt（int 占4byte）
0x0000000000202054 array0（占6byte=0x12-0x8-0x4）(正好对应其定义：char array0[6];)
0x0000000000202060 . = ALIGN ((. != 0x0)?0x8:0x1)
*fill* 0x000000000020205a 0x6.lbss
*(.dynlbss)
*(.lbss .lbss.* .gnu.linkonce.lb.*)
*(LARGE_COMMON)
0x0000000000202060 . = ALIGN (0x8)
0x0000000000202060 . = SEGMENT_START ("ldata-segment", .).lrodata
*(.lrodata .lrodata.* .gnu.linkonce.lr.*).ldata 0x0000000000602060 0x0
*(.ldata .ldata.* .gnu.linkonce.l.*)
0x0000000000602060 . = ALIGN ((. != 0x0)?0x8:0x1)
0x0000000000602060 . = ALIGN (0x8)
0x0000000000602060 _end = .
[!provide] PROVIDE (end = .)
0x0000000000602060 . = DATA_SEGMENT_END (.)解析：
> 定义的未初始化全局变量放在bss 区域
6）_end
_end 可以体现main 可执行程序最终占用的memory 是 0x 2060 byte?
7）程序执行期间打印地址，以确认上述解读是否正确
$ ./main
sum is 1
main=000055854636e83a,math=000055854636eb4d,add=000055854636eb00,sub=000055854636eac3
g_gloableInt=0000558546570050 staticInt=0000558546570040 Hello=000055854636ec08
sizeof(doubletest)=8 sizeof(testP)=8 sizeof(array0)=6
&doubletest=0000558546570018,testP=0000000000000000 array0=0000558546570054解析：
> 程序执行期间打印的是虚拟地址
> 全局函数address 与map 文件一致（低12bit 相同）
> 未初始化全局变量 address 与map 文件一致（低8byte 相同）
> 初始化全局变量 address 与map 文件一致（低8byte 相同）
> Hello 指向的是存放“HelloWorld”的address 0x000055854636ec08,对应到map 文件的这里
.rodata 0x0000000000000c08 0x14a /tmp/ccYQAtfU.o
基于以上分析，map 文件可以很准确反应程序的memory 使用情况。
8).comment
它存放的是编译器版本等信息。
9)总结
程序放在.text
常量字符串放在.rodata
全局初始化变量放在.data
全局未初始化变量放在.bss
static 函数，不体现在map 文件
static 全局变量（初始化/不初始化）都不体现在map 文件，located in .data
malloc 分配的memory 不在map 文件体现，实际在heap
可执行程序由.text / .data /.bss 3部分组成。
.text 和 .data 都存在可执行文件中，由系统从可执行文件中加载，.bss 不在可执行文件中，由系统初始化。
10）.data 与.bss 的区别
初始化全局变量，放在data 区 char array[1024*1024]={0,1,2,3};
.data 0x0000000000202020 0x100008 /tmp/ccuT7WjH.o
0x0000000000202020 array编译后的exe size 为
testC$ ls -al main -rwxrwxr-x 1 xa00000 xa00000 1061920 May 11 16:57 main
未初始化全局变量，放在bss 区 char array[1024*1024];
.bss 0x0000000000202040 0x100050
......
*(COMMON)
*fill* 0x0000000000202058 0x8
COMMON 0x0000000000202060 0x10002a /tmp/ccKlvAPJ.o
0x0000000000202060 malloc_ptr
0x0000000000202068 pInt
0x0000000000202080 array
0x0000000000302080 g_gloableInt
0x0000000000302084 array0testC$ ls -al main -rwxrwxr-x 1 xa00000 xa00000 13328 May 11 17:02 main
1061920 - 13328=1048592 byte
结论：.bss size 不占用文件空间，只占用运行时的内存空间。
11)static 变量
main.c static int tmpdata = 100; static int tmpdata_uni = 100; static void test_fun() { printf("test!"); } void main(void) { int a = 5,b = 6,sum=0; static int staticInt = 0; char data[READ_SIZE]={0}; int ret = 0; FILE* fp = fopen("abuf_apu_nbsm_o1_1_00720.mpg","r"); //FILE* fp_out = fopen("abuf_apu_nbsm_o1_1_00720_out.mpg","w+"); FILE* fp_out = fopen("abuf_apu_nbsm_o1_1_00720_out.mpg","w+"); static int tmpdata_2= 10; static int tmpdata_2_uni= 10; ...... }
testC$ objdump -t main main: file format elf64-x86-64 SYMBOL TABLE: 0000000000000238 l d .interp 0000000000000000 .interp 0000000000000254 l d .note.ABI-tag 0000000000000000 .note.ABI-tag 0000000000000274 l d .note.gnu.build-id 0000000000000000 .note.gnu.build-id 0000000000000298 l d .gnu.hash 0000000000000000 .gnu.hash 00000000000002b8 l d .dynsym 0000000000000000 .dynsym 0000000000000420 l d .dynstr 0000000000000000 .dynstr 00000000000004ec l d .gnu.version 0000000000000000 .gnu.version 0000000000000510 l d .gnu.version_r 0000000000000000 .gnu.version_r 0000000000000540 l d .rela.dyn 0000000000000000 .rela.dyn 0000000000000618 l d .rela.plt 0000000000000000 .rela.plt 00000000000006f0 l d .init 0000000000000000 .init 0000000000000710 l d .plt 0000000000000000 .plt 00000000000007b0 l d .plt.got 0000000000000000 .plt.got 00000000000007c0 l d .text 0000000000000000 .text 0000000000000d04 l d .fini 0000000000000000 .fini 0000000000000d10 l d .rodata 0000000000000000 .rodata 0000000000000e84 l d .eh_frame_hdr 0000000000000000 .eh_frame_hdr 0000000000000ee8 l d .eh_frame 0000000000000000 .eh_frame 0000000000201d78 l d .init_array 0000000000000000 .init_array 0000000000201d80 l d .fini_array 0000000000000000 .fini_array 0000000000201d88 l d .dynamic 0000000000000000 .dynamic 0000000000201f78 l d .got 0000000000000000 .got 0000000000202000 l d .data 0000000000000000 .data 0000000000202040 l d .bss 0000000000000000 .bss 0000000000000000 l d .comment 0000000000000000 .comment 0000000000000000 l df *ABS* 0000000000000000 crtstuff.c 00000000000007f0 l F .text 0000000000000000 deregister_tm_clones 0000000000000830 l F .text 0000000000000000 register_tm_clones 0000000000000880 l F .text 0000000000000000 __do_global_dtors_aux 0000000000202040 l O .bss 0000000000000001 completed.7698 0000000000201d80 l O .fini_array 0000000000000000 __do_global_dtors_aux_fini_array_entry 00000000000008c0 l F .text 0000000000000000 frame_dummy 0000000000201d78 l O .init_array 0000000000000000 __frame_dummy_init_array_entry 0000000000000000 l df *ABS* 0000000000000000 main.c 0000000000202018 l O .data 0000000000000004 tmpdata 000000000020201c l O .data 0000000000000004 tmpdata_uni 00000000000008ca l F .text 0000000000000018 test_fun 0000000000202050 l O .bss 0000000000000004 staticInt.2347 0000000000202020 l O .data 0000000000000004 tmpdata_2_uni.2353 0000000000202024 l O .data 0000000000000004 tmpdata_2.2352 0000000000000000 l df *ABS* 0000000000000000 add.c 0000000000000000 l df *ABS* 0000000000000000 dummy.c 0000000000000000 l df *ABS* 0000000000000000 crtstuff.c 000000000000108c l O .eh_frame 0000000000000000 __FRAME_END__ 0000000000000000 l df *ABS* 0000000000000000 0000000000201d80 l .init_array 0000000000000000 __init_array_end 0000000000201d88 l O .dynamic 0000000000000000 _DYNAMIC 0000000000201d78 l .init_array 0000000000000000 __init_array_start 0000000000000e84 l .eh_frame_hdr 0000000000000000 __GNU_EH_FRAME_HDR 0000000000201f78 l O .got 0000000000000000 _GLOBAL_OFFSET_TABLE_ 0000000000000d00 g F .text 0000000000000002 __libc_csu_fini 0000000000000000 F *UND* 0000000000000000 free@@GLIBC_2.2.5 0000000000202060 g O .bss 0000000000000008 malloc_ptr 0000000000202068 g O .bss 0000000000000008 pInt 0000000000000000 w *UND* 0000000000000000 _ITM_deregisterTMCloneTable 0000000000202000 w .data 0000000000000000 data_start 0000000000000c10 g F .text 000000000000004d add 0000000000000000 F *UND* 0000000000000000 fread@@GLIBC_2.2.5 0000000000202080 g O .bss 0000000000100000 array 0000000000302080 g O .bss 0000000000000004 g_gloableInt 0000000000202034 g .data 0000000000000000 _edata 0000000000202030 g O .data 0000000000000004 Min 0000000000000000 F *UND* 0000000000000000 fclose@@GLIBC_2.2.5 0000000000000d04 g F .fini 0000000000000000 _fini 0000000000000000 F *UND* 0000000000000000 __stack_chk_fail@@GLIBC_2.4 0000000000000000 F *UND* 0000000000000000 printf@@GLIBC_2.2.5 0000000000000c7c g F .text 000000000000000e dummy_ver0 0000000000000000 F *UND* 0000000000000000 __libc_start_main@@GLIBC_2.2.5 0000000000202000 g .data 0000000000000000 __data_start 0000000000000000 w *UND* 0000000000000000 __gmon_start__ 0000000000202008 g O .data 0000000000000000 .hidden __dso_handle 0000000000000d10 g O .rodata 0000000000000004 _IO_stdin_used 0000000000202028 g O .data 0000000000000008 Hello 0000000000000c90 g F .text 0000000000000065 __libc_csu_init 0000000000000000 F *UND* 0000000000000000 malloc@@GLIBC_2.2.5 0000000000302084 g O .bss 0000000000000006 array0 0000000000302090 g .bss 0000000000000000 _end 00000000000007c0 g F .text 000000000000002b _start 0000000000000000 F *UND* 0000000000000000 fseek@@GLIBC_2.2.5 0000000000202034 g .bss 0000000000000000 __bss_start 00000000000008e2 g F .text 00000000000002f1 main 0000000000000000 F *UND* 0000000000000000 fopen@@GLIBC_2.2.5 0000000000202010 g O .data 0000000000000008 doubletest 0000000000000c5d g F .text 000000000000001f math 0000000000202048 g O .bss 0000000000000008 testP 0000000000000000 F *UND* 0000000000000000 fwrite@@GLIBC_2.2.5 0000000000202038 g O .data 0000000000000000 .hidden __TMC_END__ 0000000000000000 w *UND* 0000000000000000 _ITM_registerTMCloneTable 0000000000000bd3 g F .text 000000000000003d sub 0000000000000000 w F *UND* 0000000000000000 __cxa_finalize@@GLIBC_2.2.5 00000000000006f0 g F .init 0000000000000000 _init
objdump -t main
0000000000202018 l O .data 0000000000000004 tmpdata
000000000020201c l O .data 0000000000000004 tmpdata_uni
00000000000008ca l F .text 0000000000000018 test_fun
0000000000202050 l O .bss 0000000000000004 staticInt.2347
0000000000202020 l O .data 0000000000000004 tmpdata_2_uni.2353
0000000000202024 l O .data 0000000000000004 tmpdata_2.2352conclusion:
static gloable (initialed or not-initialed) vars are located in .data
static non-gloable (initialed or not-initialed) vars are located in .data
