re: kern/49290: DRMKMS fails to work with R300

[matthew green <mrg%eterna.com.au@localhost>]

turns out mlelstv's idea doesn't work.  in a normal case, vga@isa
attaches as well, but is given wsdisplay1 and thus the problem
does not occur.

any attempts to map the VGA registers in the radeon@pci attach
do not work for pc console setups (it does work for serial.)  this
is because consinit() calls into vga and vga_init() before the
copyright is printed, and the registers are mapped here.  (ie,
attempting to map them in radeon@pci gives failure.)

i attempted to create a "radeon@isa" to attach in preference, but
even while i was able to do that eventually (relying on config
"files*" files ordering to get radeon first, vga@isa would also
attach.

mlelstv and i played around with trying to get vga to properly
detach but we were unable to get a working system yet.

as such, we are going to, for now, remove vga@isa and
pcdisplay@isa from GENERIC, and create a LEGACY kernel with those,
for use by people with pre-PCI systems..


there was an additional idea of moving vga@isa and pcdisplay@isa
into modules, and having /boot load them only on systems that
would require them.

for the PRs, reference, also see:

http://mail-index.netbsd.org/tech-kern/2015/02/28/msg018494.html

and the subsequent thread.


.mrg.