Re: [Xen-devel] [PATCH for-4.13 v2 2/3] x86/efi: properly handle 0 in pixel reserved bitmask

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

On 10/10/2019 08:13, Jan Beulich wrote:
> On 09.10.2019 22:40, Igor Druzhinin wrote:
>> --- a/xen/arch/x86/efi/efi-boot.h
>> +++ b/xen/arch/x86/efi/efi-boot.h
>> @@ -528,9 +528,15 @@ static void __init 
>> efi_arch_video_init(EFI_GRAPHICS_OUTPUT_PROTOCOL *gop,
>>          bpp = set_color(mode_info->PixelInformation.BlueMask, bpp,
>>                          &vga_console_info.u.vesa_lfb.blue_pos,
>>                          &vga_console_info.u.vesa_lfb.blue_size);
>> -        bpp = set_color(mode_info->PixelInformation.ReservedMask, bpp,
>> -                        &vga_console_info.u.vesa_lfb.rsvd_pos,
>> -                        &vga_console_info.u.vesa_lfb.rsvd_size);
>> +        if ( !mode_info->PixelInformation.ReservedMask )
>> +        {
>> +            vga_console_info.u.vesa_lfb.rsvd_pos = 0;
>> +            vga_console_info.u.vesa_lfb.rsvd_size = 0;
>> +        }
>> +        else
>> +            bpp = set_color(mode_info->PixelInformation.ReservedMask, bpp,
>> +                            &vga_console_info.u.vesa_lfb.rsvd_pos,
>> +                            &vga_console_info.u.vesa_lfb.rsvd_size);
> 
> Why not simply
> 
>         if ( mode_info->PixelInformation.ReservedMask )
>             bpp = set_color(mode_info->PixelInformation.ReservedMask, bpp,
>                             &vga_console_info.u.vesa_lfb.rsvd_pos,
>                             &vga_console_info.u.vesa_lfb.rsvd_size);
> 
> ? There's nothing I can see which might have changed
> vga_console_info.u.vesa_lfb.rsvd_{pos,size} from its zero-initialized
> value. With this adjustment (which could be done while committing) or
> with a reason supplied for the more complex code
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> 

Didn't notice it was actually statically zero-initialized. Perfectly
fine with the suggested change.

Igor

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