Hard system lockups with 10.1, probably drm/newcons/radeonkms-related

[Pete French]

"Mesa 10.3 brings major improvements in stability and performance, especially for Radeon owners, compared to Mesa 9.1. For instance, it fixes many of the GPU lockups you may see."

(from http://blogs.freebsdish.org/graphics/2014/10/17/mesa-10-3-0-committed/)

Interesting comment... am going to give new mesa a try on Monday (also
means upgrading to 10.1, but have been meaning to do that anyway).

-pete.