Re: xen-kernel and EDD

[Keir Fraser <keir@xen.org>]

On 18/08/2011 11:52, "Lin-Bao Zhang" <2004.zhang@gmail.com> wrote:

> in xen/arch/x86/boot/head.S:
> there is a code ,it will copy bootstrap trampoline to low memory below 1MB.
> 
> I am not very familar with assembler code, who can explain its target :
> I guess maybe 0x98000 has overlapped my EBDA area(95400 ~a0000) .

Well, yes, obviously it does. :-)

> -----------------------
>  /* Copy bootstrap trampoline to low memory, below 1MB. */
>         mov     $sym_phys(trampoline_start),%esi
>         mov     $bootsym_phys(trampoline_start),%edi
>         mov     $trampoline_end - trampoline_start,%ecx
>         rep     movsb
> 
>         mov     $0x98000,%esp
>         call    cmdline_parse_early
> 
>         /* Jump into the relocated trampoline. */
>         jmp     $BOOT_CS32,$bootsym_phys(trampoline_boot_cpu_entry)
> 
> #include "cmdline.S"
> 
>         .globl trampoline_start, trampoline_end
> trampoline_start:
> #include "trampoline.S"
> trampoline_end:
> 
>         .text
> __high_start:
> #ifdef __x86_64__
> #include "x86_64.S"
> #else
> #include "x86_32.S"
> #endif