On Wed, Nov 21, 2012 at 9:23 AM, H. Peter Anvin <h...@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
new_startup_64_0x400.patch
Description: Binary data
