diff mbox series

[v4,5/8] x86/boot: fold branches in video handling code

Message ID 5e4ee27b-4904-b2bc-1650-df148b47387f@suse.com (mailing list archive)
State New, archived
Headers show
Series x86/boot: (mostly) video mode handling adjustments | expand

Commit Message

Jan Beulich March 31, 2022, 9:49 a.m. UTC 
Using Jcc to branch around a JMP is necessary only in pre-386 code,
where Jcc is limited to disp8. Use the opposite Jcc directly in two
places. Since it's adjacent, also convert an ORB to TESTB.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

Comments

Roger Pau Monné April 5, 2022, 10:55 a.m. UTC | #1 
On Thu, Mar 31, 2022 at 11:49:24AM +0200, Jan Beulich wrote:
> Using Jcc to branch around a JMP is necessary only in pre-386 code,
> where Jcc is limited to disp8. Use the opposite Jcc directly in two
> places. Since it's adjacent, also convert an ORB to TESTB.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks, Roger.
diff mbox series

Patch

--- a/xen/arch/x86/boot/video.S
+++ b/xen/arch/x86/boot/video.S
@@ -332,8 +332,7 @@  lment:  movb    $0, (%di)
         cmpw    $0x656d, (%si)          # 'me'
         jnz     lmhx
         cmpw    $0x756e, 2(%si)         # 'nu'
-        jnz     lmhx
-        jmp     listm
+        jz      listm
 
 lmhx:   xorw    %bx, %bx                # Else => mode ID in hex
 lmhex:  lodsb
@@ -401,10 +400,8 @@  mode_set:
         cmpb    $VIDEO_FIRST_VESA>>8, %ah
         jnc     check_vesa
 
-        orb     %ah, %ah
-        jnz     setbad
-
-        jmp     setmenu
+        testb   %ah, %ah
+        jz      setmenu
 
 setbad: clc
         ret