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

[Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>]

In some graphics modes firmware is allowed to return 0 in pixel reserved
bitmask which doesn't go against UEFI Spec 2.8 (12.9 Graphics Output Protocol).

Without this change non-TrueColor modes won't work which will cause
GOP init to fail - observed while trying to boot EFI Xen with Cirrus VGA.

Signed-off-by: Igor Druzhinin <igor.druzhinin@xxxxxxxxxx>
---
 xen/arch/x86/efi/efi-boot.h | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h
index a0737f9..4af6314 100644
--- 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);
         if ( bpp > 0 )
             break;
         /* fall through */
-- 
2.7.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel