[Qemu-devel] [PATCH vgabios] Make windows8 work with high resolution when using -vga std in qmeu

[Bo Yang <boyang@suse.com>]

This patch has been sent to upstream vgabios maillist, but there
is no response. Since it is useful for windows8 resolution, I
resend it to qemu maillist for review.

Signed-off-by: Bo Yang <boyang@suse.com>
---
 vbe.c |   42 ++++++++++++++++++++++++++++++++++++++----
 1 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/vbe.c b/vbe.c
index 1fab2f9..eb9150c 100644
--- a/vbe.c
+++ b/vbe.c
@@ -754,6 +754,29 @@ lmulul:
   ret
 ASM_END
 
+ASM_START
+_size64:
+  push bp
+  mov  bp, sp
+  push dx
+
+; multiply bbp by yres first as results fit in 16bits
+; then multiply by xres
+  mov  ax, 8[bp]
+  mul  word 6[bp]
+  mul  word 4[bp]
+; divide by 2^19 ceiling result
+  add  ax, #0xffff
+  adc  dx, #7
+  mov  ax, dx
+  shr  ax, #3
+
+  pop  dx
+  pop  bp
+  ret
+ASM_END
+
+
 /** Function 00h - Return VBE Controller Information
  * 
  * Input:
@@ -857,7 +880,7 @@ Bit16u *AX;Bit16u ES;Bit16u DI;
 
         do
         {
-                size_64k = (Bit16u)((Bit32u)cur_info->info.XResolution * cur_info->info.XResolution * cur_info->info.BitsPerPixel) >> 19;
+                Bit16u size_64k = size64(cur_info->info.XResolution, cur_info->info.YResolution, cur_info->info.BitsPerPixel);
 
                 if ((cur_info->info.XResolution <= dispi_get_max_xres()) &&
                     (cur_info->info.BitsPerPixel <= dispi_get_max_bpp()) &&
@@ -917,14 +940,25 @@ Bit16u *AX;Bit16u CX; Bit16u ES;Bit16u DI;
 
         if (cur_info != 0)
         {
+                Bit16u max_bpp = dispi_get_max_bpp();
+                Bit16u size_64k;
+                Bit16u totalMemory;
+
+                outw(VBE_DISPI_IOPORT_INDEX, VBE_DISPI_INDEX_VIDEO_MEMORY_64K);
+                totalMemory = inw(VBE_DISPI_IOPORT_DATA);
 #ifdef DEBUG
                 printf("VBE found mode %x\n",CX);
 #endif
                 memsetb(ss, &info, 0, sizeof(ModeInfoBlock));
                 memcpyb(ss, &info, 0xc000, &(cur_info->info), sizeof(ModeInfoBlockCompact));
-                if (using_lfb) {
-                  info.NumberOfBanks = 1;
-                }
+                size_64k = size64(info.XResolution, info.YResolution, info.BitsPerPixel);
+                if ((info.XResolution > dispi_get_max_xres()) ||
+                    (info.BitsPerPixel > max_bpp) ||
+                    (size_64k > totalMemory))
+                  info.ModeAttributes &= ~VBE_MODE_ATTRIBUTE_SUPPORTED;
+
+                 /* Windows 8 require this to be 1! */
+                info.NumberOfBanks = 1;
 #ifdef PCI_VID
                 lfb_addr = pci_get_lfb_addr(PCI_VID);
 #else
-- 
1.6.0.2