Re: [PATCH] x86/efi-bgrt: Don't ignore the BGRT if the 'valid' bit is 0

[Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>]

On Sun, 20 Dec, at 10:53:11PM, Môshe van der Sterre wrote:
> Unintuitively, the BGRT graphic is apparently meant to be usable if
> the valid bit in not set. The valid bit only conveys uncertainty
> about the validity in relation to the screen state.
> 
> Windows 10 actually uses the BGRT image for its boot screen even if
> not 'valid', for example when the user triggered the boot menu.
> Because it is unclear if all firmwares will provide a usable graphic
> in this case, we now look at the BMP magic number as an additional
> check.
> ---
>  arch/x86/platform/efi/efi-bgrt.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/platform/efi/efi-bgrt.c b/arch/x86/platform/efi/efi-bgrt.c
> index b097066..a243381 100644
> --- a/arch/x86/platform/efi/efi-bgrt.c
> +++ b/arch/x86/platform/efi/efi-bgrt.c
> @@ -57,11 +57,6 @@ void __init efi_bgrt_init(void)
>  		       bgrt_tab->status);
>  		return;
>  	}
> -	if (bgrt_tab->status != 1) {
> -		pr_debug("Ignoring BGRT: invalid status %u (expected 1)\n",
> -			 bgrt_tab->status);
> -		return;
> -	}
>  	if (bgrt_tab->image_type != 0) {
>  		pr_err("Ignoring BGRT: invalid image type %u (expected 0)\n",
>  		       bgrt_tab->image_type);
> @@ -80,6 +75,11 @@ void __init efi_bgrt_init(void)
>  
>  	memcpy(&bmp_header, image, sizeof(bmp_header));
>  	memunmap(image);
> +	if (bmp_header.id != 0x4d42) {
> +		pr_err("Ignoring BGRT: Incorrect BMP magic number 0x%x (expected 0x4d42)\n",
> +			bmp_header.id);
> +		return;
> +	}
>  	bgrt_image_size = bmp_header.size;
>  
>  	bgrt_image = kmalloc(bgrt_image_size, GFP_KERNEL | __GFP_NOWARN);


Shouldn't this be pr_debug() instead of pr_err()?