qemu/pc-bios/vgabios.diff

Index: clext.c
===================================================================
RCS file: /sources/vgabios/vgabios/clext.c,v
retrieving revision 1.10
diff -u -w -r1.10 clext.c
--- clext.c	25 Mar 2006 10:19:15 -0000	1.10
+++ clext.c	14 May 2006 20:49:29 -0000
@@ -544,6 +544,13 @@
 cirrus_set_video_mode_extended:
   call cirrus_switch_mode
   pop ax ;; mode
+  test al, #0x80
+  jnz cirrus_set_video_mode_extended_1
+  push ax
+  mov ax, #0xffff ; set to 0xff to keep win 2K happy
+  call cirrus_clear_vram
+  pop ax
+cirrus_set_video_mode_extended_1:
   and al, #0x7f
 
   push ds
@@ -1011,6 +1018,13 @@
   jnz cirrus_vesa_02h_3
   call cirrus_enable_16k_granularity
 cirrus_vesa_02h_3:
+  test bx, #0x8000 ;; no clear
+  jnz cirrus_vesa_02h_4
+  push ax
+  xor ax,ax
+  call cirrus_clear_vram
+  pop ax
+cirrus_vesa_02h_4:
   pop ax
   push ds
 #ifdef CIRRUS_VESA3_PMINFO
@@ -1479,6 +1493,38 @@
   pop  bx
   ret
 
+cirrus_clear_vram:
+  pusha
+  push es
+  mov si, ax
+
+  call cirrus_enable_16k_granularity
+  call cirrus_extbios_85h
+  shl al, #2
+  mov bl, al
+  xor ah,ah
+cirrus_clear_vram_1:
+  mov al, #0x09
+  mov dx, #0x3ce
+  out dx, ax
+  push ax
+  mov cx, #0xa000
+  mov es, cx
+  xor di, di
+  mov ax, si
+  mov cx, #8192
+  cld
+  rep 
+      stosw
+  pop ax
+  inc ah
+  cmp ah, bl
+  jne cirrus_clear_vram_1
+
+  pop es
+  popa
+  ret
+
 cirrus_extbios_handlers:
   ;; 80h
   dw cirrus_extbios_80h