BUG: Win 3.1 Kernel Debugger 3.10.46 Locks Up on Pentium Sys

• Microsoft Windows Device Development Kit (DDK) for Windows, version 3.1

SYMPTOMS

When running the Microsoft Windows version 3.1 Kernel Debugger version 3.10.46 on a Pentium-based computer, a sign-on banner message will display, and the computer will subsequently lock up.

CAUSE

The Microsoft Windows 3.1 Kernel Debugger version 3.10.46 (WDEB386.EXE, 103,078 bytes) contains two machine-language instructions that are not supported by the Intel Pentium (P5) processor. These illegal instructions reference test registers, specifically the TR6 and TR7 test registers.

RESOLUTION

The following patch procedure modifies the Windows 3.1 version of the WDEB386.EXE executable file. By changing the illegal instructions into NOP instructions, the debugger will function on the Pentium processor.

1. Rename WDEB386.EXE to WDEB386.X86 to save an original copy of the Windows 80386 Debugger.

2. COPY WDEB386.X86 to WDEB386.P5. The MS-DOS debugger cannot edit files with .EXE extensions.

3. Debug WDEB386.P5. This patch procedure uses the MS-DOS debugger because of its universal availability.

4. Enter the following commands at DEBUG's '=' prompt:

   a. D64D8 - The first three bytes listed in this dump listing should

                 read:  0F  24  F0.
      b. D64DF - The first three bytes listed in this dump listing should
                 read:  0F  24  F8.
   
      NOTE: If either dump does not read EXACTLY as expected, this patch
      procedure will not fix this particular version of the Microsoft 80386
      Debugger. DO NOT continue this procedure! Quit the debugger and restore
      the original Windows 80386 Debugger file.
   
      c. E64D8  90  90  90 - changes the illegal instruction to NOPs.
   
      d. E64DF  90  90  90 - changes the illegal instruction to NOPs/
   
      e. W - Save the updated Windows 80386 Debugger.  Responds with
             "Writing 192A6 bytes."
   
      f. Q - Quit DEBUG.
   
   

5. Rename WDEB386.P5 to WDEB386.EXE.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. We are currently researching this problem and will post new information in the Knowledge Base at it becomes available.