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SubjectRe: [PATCH v3 01/12] x86, boot: move verify_cpu.S after 0x200
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On Wed, Nov 21, 2012 at 9:23 AM, H. Peter Anvin <hpa@zytor.com> wrote:
> On 11/20/2012 11:15 PM, Yinghai Lu wrote:
>>
>> We are short of space before 0x200 that is entry for startup_64.
>>
>> And we can not change startup_64 to other value --- ABI ?
>
>
> Here you are saying "I don't understand how this works." It is YOUR
> responsibility to find out and write a definite statement rather than
> leaving that to the reader, or expect the maintainer to edit this.

actually, i can not find that out.
in the code of arch/x86/boot/compressed/head_64.S

/*
* Be careful here startup_64 needs to be at a predictable
* address so I can export it in an ELF header. Bootloaders
* should look at the ELF header to find this address, as
* it may change in the future.
*/
.code64
.org 0x200
ENTRY(startup_64)
/*
* We come here either from startup_32 or directly from a
* 64bit bootloader. If we come here from a bootloader we depend on
* an identity mapped page table being provied that maps our
* entire text+data+bss and hopefully all of memory.
*/
#ifdef CONFIG_EFI_STUB
/*
* The entry point for the PE/COFF executable is 0x210, so only
* legacy boot loaders will execute this jmp.
*/
jmp preferred_addr

.org 0x210
mov %rcx, %rdi

and it says that 0x200 will be changed later..

so you said it has to stay with 0x200, do you mean 0x210 from PE/COFF
force that?

wonder if you are considering attatched patch to move startup_64 down...
we could kill one jmp.

Thanks

Yinghai
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