Re: [Qemu-devel] [PATCH master, stable-0.12] linuxboot: fix gdt address calculation

[Anthony Liguori]

On 12/24/2009 07:38 AM, Avi Kivity wrote:
> The gdt address calculation in linuxboot.bin is broken in two ways: first
> it loads %cs into %eax, but that instruction leaves the high bits of %eax
> undefined and we did not clear them.  Secondly, we completely ignore the
> incorrect %eax, and use the undefined %ebx instead.
>
> With these issues fixed, linuxboot works again.
>
> Signed-off-by: Avi Kivity<address@hidden>
>    

Applied.  Thanks.

Regards,

Anthony Liguori
> ---
>   pc-bios/optionrom/linuxboot.S |    5 +++--
>   1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
> index c4c9109..8aebe51 100644
> --- a/pc-bios/optionrom/linuxboot.S
> +++ b/pc-bios/optionrom/linuxboot.S
> @@ -86,9 +86,10 @@ copy_kernel:
>         /* Now create the GDT descriptor */
>         movw            $((3 * 8) - 1), -16(%bp)
>         mov             %cs, %eax
> +       movzwl          %ax, %eax
>         shl             $4, %eax
> -       addl            $gdt, %ebx
> -       movl            %ebx, -14(%bp)
> +       addl            $gdt, %eax
> +       movl            %eax, -14(%bp)
>
>         /* And load the GDT */
>         data32 lgdt     -16(%bp)
>