From a5c563dfdb4be1a6972498b8040f99093a262944 Mon Sep 17 00:00:00 2001
From: Aleksey Bragin <aleksey@reactos.org>
Date: Sat, 11 Sep 2010 09:20:26 +0000
Subject: [PATCH] [NTOS] - Daniel Zimmermann: Fix POPF bugs in VDM mode, namely
 truncation of the stackpointer to 16 bit and setting proper flags in the
 trapframe eflags register. This fixes problems with videocards calling int
 0x10 VESA BIOS extension. See issue #5608 for more details.

svn path=/trunk/; revision=48745
---
 reactos/ntoskrnl/ke/i386/v86vdm.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/reactos/ntoskrnl/ke/i386/v86vdm.c b/reactos/ntoskrnl/ke/i386/v86vdm.c
index 4903d3ea5f8..bcb4b16f520 100644
--- a/reactos/ntoskrnl/ke/i386/v86vdm.c
+++ b/reactos/ntoskrnl/ke/i386/v86vdm.c
@@ -70,17 +70,17 @@ KiVdmOpcodePUSHF(IN PKTRAP_FRAME TrapFrame,
     
     /* Build flat ESP */
     Esp = (TrapFrame->HardwareSegSs << 4) + (USHORT)TrapFrame->HardwareEsp;
-    Esp -= 2;
     
     /* Check for OPER32 */
     if (KiVdmGetPrefixFlags(Flags) & PFX_FLAG_OPER32)
     {
         /* Save EFlags */
-        Esp -= 2;
+        Esp -= 4;
         *(PULONG)(Esp - 2) = V86EFlags;
     }
     else
     {
+        Esp -= 2;
         /* Save EFLags */
         *(PUSHORT)Esp = (USHORT)V86EFlags;
     }
@@ -103,20 +103,24 @@ KiVdmOpcodePOPF(IN PKTRAP_FRAME TrapFrame,
     /* Build flat ESP */
     Esp = (TrapFrame->HardwareSegSs << 4) + (USHORT)TrapFrame->HardwareEsp;
     
-    /* Read EFlags */
-    EFlags = *(PULONG)Esp;
-    Esp += 4;
-    
     /* Check for OPER32 */
-    if (!(KiVdmGetPrefixFlags(Flags) & PFX_FLAG_OPER32))
+    if (KiVdmGetPrefixFlags(Flags) & PFX_FLAG_OPER32)
     {
+        /* Read EFlags */
+        EFlags = *(PULONG)Esp;
+        Esp += 4;
+    }
+    else
+    {
+        /* Read EFlags */
+        EFlags = *(PUSHORT)Esp;
+        Esp += 2;
         /* Read correct flags and use correct stack address */
-        Esp -= 2;
         EFlags &= 0xFFFF;
     }
     
     /* Set new ESP */
-    TrapFrame->HardwareEsp = Esp;
+    TrapFrame->HardwareEsp = (USHORT)Esp;
     
     /* Mask out IOPL from the flags */
     EFlags &= ~EFLAGS_IOPL;
@@ -137,7 +141,7 @@ KiVdmOpcodePOPF(IN PKTRAP_FRAME TrapFrame,
     V86EFlags |= EFLAGS_V86_MASK | EFLAGS_INTERRUPT_MASK;
 
     /* Update EFlags in trap frame */
-    TrapFrame->EFlags |= V86EFlags;
+    TrapFrame->EFlags = V86EFlags;
 
     /* Check if ESP0 needs to be fixed up */
     if (TrapEFlags & EFLAGS_V86_MASK) Ki386AdjustEsp0(TrapFrame);
@@ -311,6 +315,7 @@ KiVdmOpcodeIRET(IN PKTRAP_FRAME TrapFrame,
     else
     {
         /* FIXME: Check for VDM interrupts */
+       DPRINT("FIXME: Check for VDM interrupts\n");
     }
     
     /* We're done */