Subject: [PATCH] Fix gfxboot under VT
From: Anthony Liguori <anthony@codemonkey.ws>

This patch lets gfxboot-3.3.38 work under KVM.  The fix was suggested by Avi
Kivity.

Signed-off-by: Anthony Liguori <anthony@codemonkey.ws>

diff -ur a/bincode.asm b/bincode.asm
--- a/bincode.asm	2007-07-24 05:49:46.000000000 -0500
+++ b/bincode.asm	2007-09-29 22:14:35.000000000 -0500
@@ -15519,6 +15519,7 @@
 switch_to_pm:
 		pushf
 		push eax
+		push ebx
 
 		mov eax,cr0
 
@@ -15534,6 +15535,11 @@
 		mov word [cs:rm_seg.fs],fs
 		mov word [cs:rm_seg.gs],gs
 
+		;; ss:rpl must equal cs:rpl in PM for VT.  we can't rely on ss
+		;; maintaining it's value after the transition so we have to
+		;; pass it in a GP register
+		mov ebx,ss
+	
 		or al,1
 		o32 lgdt [cs:pm_gdt]
 		o32 lidt [cs:pm_idt]
@@ -15546,7 +15552,7 @@
 		mov ax,pm_seg.prog_d16
 		mov ds,ax
 
-		mov eax,ss
+		mov eax,ebx
 		and esp,0ffffh
 		shl eax,4
 		add esp,eax
@@ -15557,6 +15563,7 @@
 		mov fs,ax
 		mov gs,ax
 
+		pop ebx
 		pop eax
 		popfw
 		o16 ret