Porting DRM/GEM from OpenBSD

[Grégoire Sutre <gregoire.sutre%gmail.com@localhost>]

I could make the Intel Xorg driver run on a Core i5 laptop, by
porting OpenBSD's DRM/GEM driver to NetBSD.  The integrated panel
on this laptop is on an embedded display port (eDP), so I also
backported the Intel (e)DP driver from Linux to Xorg.  The sources,
along with a README giving more details, are at:

https://github.com/gsutre/netbsd-drmgem

and some pre-built binaries are available at:

ftp://ftp.netbsd.org/pub/NetBSD/misc/gsutre/

I did not include display-port support by default in these
pre-built archives, to limit the number of bugs I introduced. ;-)
(Well, the amd64 archive has it, but it's hidden.)

The port is currently limited to Intel chipsets.  I tested it
(a bit) on Ironlake (Core i5) and (a lot) on i915.  If you give
it a try, I'd be happy to hear about it.

Warning: You may get gpu hangs that seem to be related to
timings (see https://github.com/gsutre/netbsd-drmgem/issues).
Returning to the console should still be possible, though.
As a workaround, enabling DebugWait in xorg.conf makes these
gpu hangs disappear for me.

There is still a lot of room for improvement (volunteers?),
but I hope that this is a step in the right direction to get
DRM/GEM(/KMS) support in NetBSD.

Best regards,

Grégoire

p.s. I'm mostly interested in basic desktop usage, so I didn't
look (much) into 3D, XvMC, etc.