[Qemu-devel] ping RE: [PATCH v3] SGABIOS: fix wrong video attrs for int 10h, ah==13h

[Robinson, Herbie]

http://patchwork.ozlabs.org/patch/737446/


-----Original Message-----
From: Laurent Vivier [mailto:address@hidden 
Sent: Friday, March 10, 2017 2:10 PM
To: Robinson, Herbie <address@hidden>; address@hidden
Cc: address@hidden
Subject: Re: [PATCH v3] SGABIOS: fix wrong video attrs for int 10h, ah==13h

On 10/03/2017 16:54, Herbie Robinson wrote:
> Fix Bug #1670509: wrong video attrs for int 10h, ah==13h The 
> subroutine set_cursor_position is trashing %bx.
> Unfortunately, %bl contains the video attribute for write_string.
> 
> The fix saves %bx in the function prolog and restores it in the 
> epilog.
> 
> Signed-off-by: Herbie Robinson <address@hidden>

Reviewed-by: Laurent Vivier <address@hidden>


> ---
> Removed incorrect code deletions from set_current_cursor.
> Removed explanation of same from the commit message.
> 
> BTW, I didn't see any test cases for this code, but if they exist and 
> somebody points me at them, I should be able to generate a very small 
> qcow2 file that demonstrates the problem.
> 
>  sgabios.S | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/sgabios.S b/sgabios.S
> index 275d063..96c4e23 100644
> --- a/sgabios.S
> +++ b/sgabios.S
> @@ -1728,6 +1728,7 @@ write_string_tail:
>  
>  set_cursor_position:
>    pushw %ax
> +  pushw %bx
>    pushw %ds
>    pushw $BDA_SEG
>    popw %ds                             /* ds = 0x40 */
> @@ -1738,6 +1739,7 @@ set_cursor_position:
>    movw %ax, %bx                        /* bx = cursor save offset */
>    movw %dx, (%bx)                      /* save new cursor value */
>    popw %ds
> +  popw %bx
>    popw %ax
>    ret
>  
>