On Tue, 31 Oct 2000, Corin Talkobt wrote:
> Let me argue the opposite approach for a bit Virtualizing the VGA
> access.
>
> There are several advantages to this: 1) It would provide support for
> OS's other than Windows ( how does running Windows within X within X
> within X sound? ).
Nested runs of plex86 doesn't seem very useful to me.
2) Full-Screen mode could be modified, as appropriate
> to bypass the virtualization mode so apps could still run in
> full-screen.
of course, I never was against windowizing, I just don't believe it will
be enough fast for gfx-heavy guests.
3) With a "shallow" virtualization there would be no
> noticable loss in performance.
>
When providing just a basical access to framebuffer, yes, when providing a
wrapper for 2d/3d acceleration, not so sure.. also, the quality and
compatibility could suffer for a little bit in this case.
> Point 3 is the probable sticking point. The basic problem is mapping one
> video system into another. By translating the VGA registers 'et all into
> a simplified set ( perhaps do what some of the Commodore emulators do
> and have a sub-thread perform a scanline sweep to determine what to
> display ), I don't think performance would be that impacted.
Again, Commodore machines were good for that time.. modern pc accels are
far more advanced to be virtualized efficiently (I might be wrong, but I
doubt it).
> This would
> also avoid the issue with worrying about the amount of memory within the
> video buffer etc.
>
yeah, that's a problem :-(
> The virtualization I'm thinking of would implement a modest but capable
> "video set" and then the guest OS would use the driver for that "modest
> but capable" video set.
>
it's a good idea.. however I wished to have full-blown features without
the loss of performance.. maybe my idea isn't realistic though.
> The problems I see with no virtualizing is it that basically you'll be
> unable to run plex86 more than once.
well, that's not a very major restriction..
> This would arrise out of the issue
> with over-riding management of the Video Card's ram. There would also be
> problems with running it windowed in differant color settings etc..
> Doing partial virtualization in windowed mode would run into color
> translation, bitmap plane issues etc.
>
yeah, it's pretty tricky, however windowized support, especially of 2d/3d
axel will be pretty tricky anyway..
Uhus
