X-Git-Url: https://gerrit.opnfv.org/gerrit/gitweb?a=blobdiff_plain;f=qemu%2Froms%2Fseabios%2Fvgasrc%2Fvgabios.c;h=f07e85bd339b5ab37912f3e06c37f6fa06ba40e7;hb=437fd90c0250dee670290f9b714253671a990160;hp=4aa50e1c19bd2bf561f3d5c4dc364cb6b6b82a67;hpb=e44e3482bdb4d0ebde2d8b41830ac2cdb07948fb;p=kvmfornfv.git

diff --git a/qemu/roms/seabios/vgasrc/vgabios.c b/qemu/roms/seabios/vgasrc/vgabios.c
index 4aa50e1c1..f07e85bd3 100644
--- a/qemu/roms/seabios/vgasrc/vgabios.c
+++ b/qemu/roms/seabios/vgasrc/vgabios.c
@@ -304,6 +304,12 @@ vga_set_mode(int mode, int flags)
         SET_BDA(video_mode, 0xff);
     SET_BDA_EXT(vbe_mode, mode | (flags & MF_VBEFLAGS));
     SET_BDA_EXT(vgamode_offset, (u32)vmode_g);
+    if (CONFIG_VGA_ALLOCATE_EXTRA_STACK)
+        // Disable extra stack if it appears a modern OS is in use.
+        // This works around bugs in some versions of Windows (Vista
+        // and possibly later) when the stack is in the e-segment.
+        MASK_BDA_EXT(flags, BF_EXTRA_STACK
+                     , (flags & MF_LEGACY) ? BF_EXTRA_STACK : 0);
     if (memmodel == MM_TEXT) {
         SET_BDA(video_cols, width);
         SET_BDA(video_rows, height-1);