Xorg-6.8.x: VT switching on a linuxPPC with a GeForce2MX card is broken --- How to fix it.

[Joseph E. Sacco, PhD]

VT switching on a linuxPPC with an NVIDIA GeForce2MX card running
Xorg-6.8.2 or Xfree86-4.5 is broken.

Attached is a patch to fix the problem.

Discussion
-------------
The resolution of the VT switching problem was a collaboration with
Mark Vojkovich <mvojkovi at XFree86.Org>

Observations:
* the nv driver for Xorg and Xfree86 are very similar.
* Mark is a maintainer of the nv driver code [among many other things]
for the XFree86.org and knows the nv code well [:-)].
* VT switching used to work for earlier versions of X, in particular
Xfree86-4.4. 

Approach:
Identify the root cause using bisection.

I proposed using bisection on the time-line of the CVS code for the
Xfree86 version of the nv driver to identify a point on the time-line
when VT switching first stopped working.

The CVS command,

	cvs -D "DATE_SPEC" update

was used to pull down nv driver code from the XFree86.org CVS repository
with the most recent version of any file no later than DATE_SPEC.

After several iterations, a point on the time-line was identified when
VT switching first failed.  Mark was then able to compare the errant
code with working code from an earlier point on the time-line, deduce
the cause of the problem and construct a solution.

-Joseph

-- 
joseph_sacco [at] comcast [dot] net
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