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

[Jan Beulich <jbeulich@xxxxxxxx>]

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>

Jan

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