[xen staging-4.20] x86/boot: don't blindly mark VGA in graphics mode on MB2 path

[patchbot@xxxxxxx]

commit 8a44c61b2d4b04d28a6124bc71f5526aad100177
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jun 30 15:01:18 2026 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jun 30 15:01:18 2026 +0200

    x86/boot: don't blindly mark VGA in graphics mode on MB2 path
    
    Setting ->orig_video_isVGA to the specific marker should be done only when
    the VBE tag is present and the FRAMEBUFFER is either absent or indicates
    RGB type. Since the "video" variable now starts out non-NULL, this
    property was broken when in particular neither of the tags are present. To
    move back to at least close to original behavior, add a 2nd check to said
    conditional.
    
    Fixes: d5a73cdc6b90 ("x86/boot: Use boot_vid_info variable directly from C 
code")
    Reported-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Teddy Astie <teddy.astie@xxxxxxxxxx>
    master commit: c7b742985499a5e99456456bac47a13b2987e550
    master date: 2026-06-25 13:37:33 +0200
---
 xen/arch/x86/boot/reloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/boot/reloc.c b/xen/arch/x86/boot/reloc.c
index 7a375ad41c..2aa6ebb16b 100644
--- a/xen/arch/x86/boot/reloc.c
+++ b/xen/arch/x86/boot/reloc.c
@@ -339,7 +339,7 @@ static multiboot_info_t *mbi2_reloc(uint32_t mbi_in, memctx 
*ctx)
  end:
 
 #ifdef CONFIG_VIDEO
-    if ( video )
+    if ( video && video->lfb_size )
         video->orig_video_isVGA = 0x23;
 #endif
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging-4.20