William Josephson wrote:
On Fri, Mar 10, 2006 at 04:31:31PM -0500, [EMAIL PROTECTED] wrote:
To be fair, it's not the 'standard's that are at fault here.
Using VESA requires taking the processor out of protected mode
and jumping into the BIOS and that's difficult with 2 processors
as we need to make sure they are all agreed on what's going on
and interrupts are properly disabled, etc. The Plan 9 x86 SMP
code wasn't written with those goals in mind. It should be possible
but clearly we didn't get it right and it's a low-priority item.
You can also use VM86 mode on 386 (but not AMD/x86-64).
It actually isn't so bad -- I'd have to think it would
be much easier than going back to real mode. Of course,
it isn't an option on 64-bit machines, which may effectively
leave you in the same place.
As cool as I think the VESA stuff is, our experience is that it's also a
mistake to do it via switch to 16-bit mode. Making it work right gets
really tricky, as you just learned with SMP; that's only one possible
hazard. We've been enabling graphics with an emulator-based approach for
a few years now, and it does work well. Code available in the linuxbios
source tree, if anybody wants to mess around with it.
thanks
ron
