PRB: DBWIN Sample Application May Appear to Hang Windows

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1

SYMPTOMS

When using the Microsoft Windows Software Development Kit (SDK) version 3.1, Windows may appear to hang if the following three items are true:

1. You are using the DBWIN sample application (DBWIN.EXE--see pages 245- 247 of the Windows SDK "Programming Tools" manual) to catch the output of the debug kernel.

2. There is no other output device, other than DBWIN.

3. The "Break on Warnings" option is set in DBWIN.

CAUSE

Upon entry to Windows, warnings may be displayed by the debug kernel. If the Break on Warnings option is set as an option in the DBWIN sample application and the Save Debug Settings is chosen from the File menu, DBWIN will save the option in the DebugOptions setting of the WIN.INI file under the [WINDOWS] header. Windows reads the WIN.INI file on startup and sees that bit number 12 of the DebugOptions field under the [WINDOWS] heading has been set (0x1000).

If bit number 12 has been set and warnings are generated before the DBWIN application is started, the debug kernel will generate fatal exit warnings. Because there is no output screen defined (because DBWIN is not running yet and there is no alternate output screen), the system will appear to be hung, when in reality it is waiting for input. However, because DBWIN has not defined where the input will come from, the only solution is to reboot and change the WIN.INI (or SYSTEM.INI) settings before entering Windows (See RESOLUTION for details).

RESOLUTION

To work around the problem, do one of the following:

1. Change the DebugOptions setting in the WIN.INI file under the [WINDOWS] heading. The value listed will be a four-digit hexadecimal number. The first digit must be changed to an even number to ensure that bit number 12 is not set (for example, 0x3000 should be changed to 0x2000). This method will cause the Break on Warnings option in DBWIN to be unchecked.

2. Add the following section to the SYSTEM.INI file:

         [debug]
         OutputTo=NUL
   

   A filename could replace NUL in the above statement if desired.

MORE INFORMATION

To reproduce the problem, do the following:

1. Ensure that you are running the debug kernel (run N2D.BAT from the MS- DOS prompt before entering Windows).

2. Run the DBWIN sample application.

3. Choose Settings from the Options menu.

4. Ensure that the Break on Warnings check box is checked.

5. Choose OK.

6. Choose Save Debug Settings from the File menu.