Call for Testing: UEFI Changes

Hello!

A number of changes have gone in recently pertaining to UEFI booting
and UEFI runtime services. The changes with the most damaging
potential are:

We now put UEFI runtime services into virtual address mode, fixing
runtime services with U-Boot/UEFI as well as the firmware
implementation in many Lenovos. The previously observed behavior was a
kernel panic upon invocation of efibootmgr/efivar, or a kernel panic
just loading efirt.ko or compiling EFIRT into the kernel.

Graphics mode selection is now done differently to avoid regression
caused by r327058 while still achieving the same effect. The observed
regression was that the kernel would usually end up drawing
incorrectly at the old resolution on a subset of the screen, due to
incorrect framebuffer information.

Explicit testing of these changes, the latest of which happened in
r331326, and any feedback from this testing would be greatly
appreciated. Testing should be done with either `options EFIRT` in
your kernel config or efirt.ko loaded along with updated bootloader
bits.

I otherwise plan to MFC commits involved with the above-mentioned
changes by sometime in the first week of April, likely no earlier than
two (2) weeks from now on April 4th.

Thanks,

Kyle Evans