Re: [Qemu-devel] GSoC projects about AHCI and S3 Trio

[Paul Brook <paul@codesourcery.com>]

> I will contact jai  soon about the S3 Trio. I'll also skim through the
> documentation so that I can set reasonable goals in my timeline.

TBH I'm less convinced about the utility of emulating an S3 graphics card. 
You'd want to make sure you know what you're expecting from it.
While it may have a bit wider OS support that the Cirrus Logic cards, it's 
still an extremely old card that AFAIK ceased production many years ago.
In modern terms it also has extremely limited capabilities.

Even the 2D engine is likely to be tricky accelerate because. The framebuffer 
is exposed to the guest, so you have to accomodate the guest reading back the 
results.

Some models have rudimentary 3D acceleration, however in practice I doubt this 
is worth much. I did a bit of 3D graphics when these cards were common, and 
IIRC they're missing some common features (multitexturing, possibly even 
prespective correction) and [as real hardware] are generally slower than a 
good software renderer.

If you want useful 3D acceleration, then you pretty much have to go for a 
paravirtual interface.  The interface exposed by real hardware is closely tied 
to the implementation, which makes it hard (and slow) to emulate.  This has 
been discussed a few times before, and amounts to feeding OpenGL commands (or 
equivalents such as Gallium pipes) over a remote transport.

Paul