hi all:
2008/10/26 Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx>:
> Hi
>
> On Sat, Oct 25, 2008 at 10:02 PM, loody <miloody@xxxxxxxxx> wrote:
>> Dear all:
>> I find there is a section in vmlinux.lds defined as below:
>> _got_start = .;
>> .got : { *(.got) }
>> _got_end = .;
>> .got.plt : { *(.got.plt) }
>> .data : { *(.data) }
>> _edata = .;
>>
>> As far as I know, this file is used to generate vmlinux.lds and ld
>> will use it to combine compressed kernel, proper head.s, by different
>> cpu, and misc.c to zImage.
>>
>> so I think the .got sections will be defined in obj codes in this
>> folder, compressed.
>> But I cannot get any information about got, could someone tell me
>> where it is and what it is used for?
>
> In short, GOT (global offset table) holds the address of external
> functions (functions on external libraries). You can read more about
> it in my article here:
> http://www.linuxforums.org/misc/understanding_elf_using_readelf_and_objdump.html
>
> regards,
>
> Mulyadi.
>
sorry for interrupt your conversation right now.
after peruse the web you mention there is a phrase i cannot quite understand.
you take below as an example:
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
[00] PHDR 0x000034 0x08048034 0x08048034 0x000e0 0x000e0 R E 0x4
[01] INTERP 0x000114 0x08048114 0x08048114 0x00013 0x00013 R 0x1
[02] LOAD 0x000000 0x08048000 0x08048000 0x004fc 0x004fc R E 0x1000
[03] LOAD 0x0004fc 0x080494fc 0x080494fc 0x00104 0x0010c RW 0x1000
[04] DYNAMIC 0x000510 0x08049510 0x08049510 0x000c8 0x000c8 RW 0x4
[05] NOTE 0x000128 0x08048128 0x08048128 0x00020 0x00020 R 0x4
[06] STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RW 0x4
[1] 0039d000-003b2000 r-xp 00000000 16:41 1080084 /lib/ld-2.3.3.so
[2] 003b2000-003b3000 r--p 00014000 16:41 1080084 /lib/ld-2.3.3.so
[3] 003b3000-003b4000 rw-p 00015000 16:41 1080084 /lib/ld-2.3.3.so
[4] 003b6000-004cb000 r-xp 00000000 16:41 1080085 /lib/tls/libc-2.3.3.so
[5] 004cb000-004cd000 r--p 00115000 16:41 1080085 /lib/tls/libc-2.3.3.so
[6] 004cd000-004cf000 rw-p 00117000 16:41 1080085 /lib/tls/libc-2.3.3.so
[7] 004cf000-004d1000 rw-p 004cf000 00:00 0
[8] 08048000-08049000 r-xp 00000000 16:06 66970 /tmp/test
[9] 08049000-0804a000 rw-p 00000000 16:06 66970 /tmp/test
[10] b7fec000-b7fed000 rw-p b7fec000 00:00 0
[11] bffeb000-c0000000 rw-p bffeb000 00:00 0
[12] ffffe000-fffff000 ---p 00000000 00:00 0
and you mention 'Do you see the similarity between VMA #8 and segment
#02 listed in PHT? "
But i still cannot see relationship between
VMA[8] 08048000-08049000 r-xp 00000000 16:06 66970 /tmp/test and
[02] LOAD 0x000000 0x08048000 0x08048000 0x004fc 0x004fc R E 0x1000
Did I missing anything?
appreciate your help,
vichy
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