What this setting does is disable support for the specified extension. The
problem here is that the application uses the extension in a problematic way:
by the way the extension is phrased, it should only work for allocations at a
page-level granularity. X-Plane 10 tries to use it for a different granularity
and doesn't check for error results (which it really must).

We could hack around the page-level granularity limitations in the same way
that the closed-source driver does it, but I'm hesitant to do so because it can
never be a complete fix: if two pinned buffers overlap on the same page, we
simply cannot support that currently. So who knows what other potential
application bugs we'd just be papering over.

As for a patch, we might add a driconf-based application-specific workaround
for this.