[9fans] nvidia vs. dual processors

[erik quanstrom <quanstro@quanstro.net>]

i've been having problems with aux/vga when running
on a dual processor machine.  before the recient update
to aux/vga, the machine would get stuck in /sys/src/9/pc/vganvidia.c/^waitforidle.
the iprints would be painfully slow and the machine would became
unusable afterwards.  even "aux/vga -p" would exhibit this.
various three-fingered salutes would impress nobody.

after the recient update, "aux/vga -p" works but "monitor=vesa aux/vga -p"
puts the machine into a fairly unusable state as soon as the output hits
the bottom of the window.  the cursor makes big jumps, lags many seconds
and doesn't quite track rio's idea of the cursor location.  i coudn't
manage to select a window to to do fshalt, so i rebooted. (via the keboard.)

(this doesn't happen if i boot *nomp=1.)

i think vganvidia.c/^nvidiahwscroll is conflicting with the vesa requests in aux/vga.

in an unrelated problem. *nomp or not, the screen is shifted to the left 1".
(it works fine at the same video mode on linux.)  i'm not sure what the problem
might be.  any ideas?

- erik