Patch-ID# 100494-01
Keywords: munmap, gs, xgl, ctl, register, page, shmem, allocation 
Synopsis: SunOS4.1.1;4.1.2: munmap'ing ctl register page clobbers shmem buffer
Date: 01-Feb-92
 
SunOS release: 4.1.1GFXRev2 and 4.1.2
 
Unbundled Product: NA
 
Unbundled Release: NA 
 
Topic: GS kernel patch.
 
BugId's fixed with this patch: 1074822

Architectures for which this patch is available: sun4c

Patches which may conflict with this patch:

Obsoleted by:

Problem Description: 

   The XGL DGA double buffering code mmaps the page containing the vertical
   retrace counter register, then munmaps it when double buffering is disabled.
   This munmap has the side effect of disturbing the status of the allocated
   shared memory blocks, marking some as unalloc'ed when they're really in
   use, and others as alloc'ed when they aren't.  Posting a buffer that is no
   longer allocated sometimes hangs the GS, forcing reloading of the microcode.
   This is causing a customer application layered on top of XGL to crash on the
   GS.


INSTALL: 

  1) Become root and save your exsiting driver:

    cp -p /sys/sun4c/OBJ/cgtwelve.o /sys/sun4c/OBJ/cgtwelve.o.FCS

  2) cp sun4c/{4.1.1; 4.1.2}/cgtwelve.o /sys/sun4c/OBJ

  3) Rebuild the kernel. The steps for rebuilding the kernel are in your
     system Administration manual