Comment # 31 on bug 1004453 from Max Staudt

Okay, the original problem was that xf86-video-mga no longer works when vesafb
is in use. Correct?

It seems I missed something:
[    58.382] (EE) MGA(0): Unable to map Framebuffer F0000000 2000000.  Invalid
argument (22)

It could be that it can no longer map the VRAM when it is already in use by
vesafb. We see similar things with KMS drivers when a userspace process keeps a
memory region open.

So maybe a kernel change has disallowed simultaneous mappings of that memory
region...?

That could also explain why the mga module isn't loaded (not that it's needed
anyway).