> > > VGAs which don't support a linear framebuffer are out here (and as a
> > > band-aid can still be used with the old XFree86 servers).
> > Or the driver can use mmap() to create a pseudo-linear framebuffer
> > out of the banks. KGI does this.
>
> What about bitplane modes? Okay, that's really sick ;-)
That is still a linear framebuffer, just laid out differently.
> (When I first assembled the machine I'm now working on I didn't have
> the right video card, so I put in an old, unsupported VGA. Yes I got
> it to work with the vga16 driver and even in a reasonable resolution,
> but it is flabbergasting how slow a K6/233 can get with the "right"
> peripherals ;-)
Yep. All that witing on the ISA bus, all that bank-remapping, and
no acceleration.
> > You'd get a little more speed out of having the X server sit right
> > on top of the kernel and feed ioctls to /dev/fb, but the portability loss
> > wouldn't (IMHO) be worth it.
>
> OK, ioctls are suboptimal for various reasons, but MMIO access to the
> hardware still has a stability risk, at least with poorly designed
> VGAs which seem to be the majority. :-(
Yep. Up until recently, the only part of an SVGA video card that
would be pushed very hard would be the VGA core. The SVGA part would just
be used by windows usually, especially the acceleration, and they could
code the drivers around the hardware bugs and no one would know. And
especially given the intense competitive pressure that has been around in
the video card market over the last five years, if your product had a bug
it had to be shipped anyway because if another card was ready earlier, all
the OEMs would switch over to it and you'd be screwed out of profits vital
to the continued development of your products.
Jon
--- 'Cloning and the reprogramming of DNA is the first serious step in becoming one with God.' - Scientist G. Richard Seed
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