[Xen-changelog] [xen-unstable] [HVM][DM] Cleaner way of clearing VGA memory on mode changes (thanks to

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 2fd2fd4b7c6a93e80b107dab9241d5790ba12f6f
# Parent  f8af7041bf5b4a6529225f2be225fbf2cce71f72
[HVM][DM] Cleaner way of clearing VGA memory on mode changes (thanks to
Fabrice Bellard on the QEMU project). This patch clears the
memory in the BIOS call rather than when the Cirrus Logic register changes,
which more closely matches what happens on the real hardware.

Signed-off-by: Don Dugger <donald.d.dugger@xxxxxxxxx>
---
 tools/firmware/vgabios/clext.c |   46 +++++++++++++++++++++++++++++++++++++++++
 tools/ioemu/hw/cirrus_vga.c    |   11 ---------
 2 files changed, 46 insertions(+), 11 deletions(-)

diff -r f8af7041bf5b -r 2fd2fd4b7c6a tools/firmware/vgabios/clext.c
--- a/tools/firmware/vgabios/clext.c    Wed Jun 07 14:07:36 2006 +0100
+++ b/tools/firmware/vgabios/clext.c    Wed Jun 07 14:13:22 2006 +0100
@@ -525,6 +525,13 @@ cirrus_set_video_mode_extended:
 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
@@ -992,6 +999,13 @@ cirrus_vesa_02h_1:
   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
@@ -1460,6 +1474,38 @@ cirrus_get_start_addr:
   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
diff -r f8af7041bf5b -r 2fd2fd4b7c6a tools/ioemu/hw/cirrus_vga.c
--- a/tools/ioemu/hw/cirrus_vga.c       Wed Jun 07 14:07:36 2006 +0100
+++ b/tools/ioemu/hw/cirrus_vga.c       Wed Jun 07 14:13:22 2006 +0100
@@ -1191,17 +1191,6 @@ cirrus_hook_write_sr(CirrusVGAState * s,
        s->hw_cursor_y = (reg_value << 3) | (reg_index >> 5);
        break;
     case 0x07:                 // Extended Sequencer Mode
-       /* Win2K seems to assume that the VRAM is set to 0xff
-        *   whenever VGA/SVGA mode changes 
-        */
-       if ((s->sr[0x07] ^ reg_value) & CIRRUS_SR7_BPP_SVGA)
-           memset(s->vram_ptr, 0xff, s->real_vram_size);
-       s->sr[0x07] = reg_value;
-#ifdef DEBUG_CIRRUS 
-       printf("cirrus: handled outport sr_index %02x, sr_value %02x\n",
-              reg_index, reg_value);
-#endif
-       break;
     case 0x08:                 // EEPROM Control
     case 0x09:                 // Scratch Register 0
     case 0x0a:                 // Scratch Register 1

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