Bug Report

CWSDPMI/VBEPLUS/GF4 VIDEO BIOS incompatibility

Summary:

Running programs using VBEPLUS and GF4 video cards result in a complete
lockup on video initialization (a black screen).  The problem does not
occur on GF2 Pro or if VBEPLUS is not loaded.

Analysis:

Increasing the real mode stack allocation inside CWSDPMI (bigstack.zip)
allowed programs to run.  VBEPlus TSR uses 28 bytes of stack; UniRefresh
uses 26 bytes of stack; the combination (plus the GF4 bios) used 284 bytes
of stack (GF4 BIOS uses 230 bytes!).  The DPMI spec indicates interrupts 
should allocate and specify their own stack if more than 60 bytes are used.  
CWSDPMI only provides 256 bytes and the stack overflowed.

Workarounds:

Unless there is a BIOS upgrade for GF4, no real workarounds except using 
bigstack.zip.  Increase default CWSDPMI stack size in some future release.