[Intel-gfx] What's the story with Gallium and Intel GPUs?

[Dave Airlie]

On Tue, Jan 26, 2010 at 7:06 PM, Olivier Galibert <galibert at pobox.com> wrote:
> Or that could be "Is there a story in the first place?" :-)
>
> I'm interested in intel gfx hardware (it's what I have in my laptop),
> and I'd like to see if I can help things up to the point where I can
> play with geometry shaders and stuff.  Maybe I can, maybe I can't,
> time will tell.
>
> One of the things I'm trying to figure out is the place of Gallium in
> all that.  Having it in the separate directory with separate drivers
> in the mesa git is a little strange, and google only says that the
> intel gfx devs are not interested by gallium at that point.

Thats not that strange, gallium drivers are separate drivers they
don't sit in the same place in the tree as they are different.

>
> One the other hand, it looks like it may be a requirement for GLSL
> 1.5/OpenGL 3.2 (in the future, obviously).

Not really. Gallium is a driver architecture, it doesn't mean its
impossible to do things in other ways.

>
> So what is it?  A future requirement?  An alternative way of doing
> things?  Is the interest in gallium for intel gpus only deferred until
> kms/uxa is considered stable or there is an active rejection going on?
> And if so, where should I look for the technical reasons, if any?

Gallium is a new driver architecture, which means the drivers have to
be written from close to scratch to use it. This means introducing a lot
of regressions and expending a lot of time to get the gallium  based mesa
driver back to the same level as the current Intel Mesa driver. So
far Intel haven't decided that the end outweighs the transisition.
The Intel drivers have undergone a pretty major rewrite already and really
only just started coming back out the other side about 6 months ago,
doing this again is probably not the easiest path to happiness.

So I don't think the Intel devs are willing to undergo this process again
so soon, there may be some point that the advantages of the G3D
architecture outweighs the pain and suffering in moving a driver to it.

There are community maintained i915g/i965g drivers (mostly VMware
devs) and there is plenty of work on those to be done.

Dave.