* Re: [Qemu-devel] [PATCH master, stable-0.12] linuxboot: fix gdt address calculation
[not found] <1261661930-11888-1-git-send-email-avi@redhat.com>
@ 2010-01-08 16:41 ` Anthony Liguori
0 siblings, 0 replies; only message in thread
From: Anthony Liguori @ 2010-01-08 16:41 UTC (permalink / raw)
To: Avi Kivity; +Cc: Marcelo Tosatti, qemu-devel, kvm
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<avi@redhat.com>
>
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)
>
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