Re: [PATCH]x86_64: build and use GDT on copied compressed kernel

From: Eric W. Biederman
Date: Sun May 13 2007 - 03:07:35 EST


"Yinghai Lu" <yhlu.kernel@xxxxxxxxx> writes:

> On 5/12/07, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>>
>> For data segments we never use that GDT, it is only for the code
>> segment we use the GDT and that only to get us into 64bit mode.
>>
>
> after the patch
> linux:/home/yhlu/xx/xx/kernel/linux-2.6/arch/x86_64/boot/compressed #
> readelf -e vmlinux
> ...
> Section Headers:
> [Nr] Name Type Address Offset
> Size EntSize Flags Link Info Align
> [ 0] NULL 0000000000000000 00000000
> 0000000000000000 0000000000000000 0 0 0
> [ 1] .text PROGBITS 0000000000000000 00100000
> 000000000032617c 0000000000000000 AX 0 0 16
> [ 2] .rodata PROGBITS 0000000000326180 00426180
> 0000000000000400 0000000000000000 A 0 0 32
> [ 3] .eh_frame PROGBITS 0000000000326580 00426580
> 0000000000000210 0000000000000000 A 0 0 8
> [ 4] .data PROGBITS 0000000000326790 00426790
> 0000000000000008 0000000000000000 WA 0 0 8
> [ 5] .bss NOBITS 00000000003267a0 00426798
> 000000000000b860 0000000000000000 WA 0 0 32
> [ 6] .comment PROGBITS 0000000000000000 00426798
> 0000000000000035 0000000000000000 0 0 1
> [ 7] .shstrtab STRTAB 0000000000000000 004267cd
> 0000000000000047 0000000000000000 0 0 1
> [ 8] .symtab SYMTAB 0000000000000000 00426a98
> 00000000000007c8 0000000000000018 9 60 8
> [ 9] .strtab STRTAB 0000000000000000 00427260
> 0000000000000350 0000000000000000 0 0 1
> Key to Flags:
> W (write), A (alloc), X (execute), M (merge), S (strings)
> I (info), L (link order), G (group), x (unknown)
> O (extra OS processing required) o (OS specific), p (processor specific)
>
> after the patch, it seems .data section size still have 8 bytes.
> before that will 0x28.
> don't know what are the 8 bytes.

Probably variables in misc.c


Eric
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