i think that's what we found when we did VESA-based
work for Inferno.  i'm happy to parcel that up yet
again if anyone's seriously interested in adapting it
for Plan 9, or even current Inferno, or anything else
for that matter, but it takes time to find all the bits,
so be reasonably sure you're going to have the stamina.
other `buts': it relied on software cursors in Inferno;
it relied on non-trivial changes to the bootstrap code
to do real-mode (unreal mode more like) BIOS calls
to gather data before loading the kernel, because cards
didn't implement the 32-bit variants; and it's all
a bit involved.