Issues with i915drmkms on AMD64

[David Mackay <davidm.jx8p%gmail.com@localhost>]

Today I've attempted to try out the new i915drmkms support on NetBSD
6.99.47-CURRENT. I've built the DRMKMS kernel conf and installed its
modules, and attempted to boot.

Unfortunately, despite having all relevant debug options checked, it
seems that NetBSD kernel simply freezes after displaying the line:

i915drmkms0 at pci0 dev 2 function 0 [...]

I've also tried the prebuilt kernel from Nonaka at
http://ftp.netbsd.org/pub/NetBSD/misc/nonaka/drmkms/ which did not
work either, except in its case, the screen was blanked and then
froze.

On the other hand, gsutre's DRMGEM *does* work fine.

This is on a ThinkPad T410 with an i5-560m CPU and Intel IronLake HD Graphics.