Re: [Dri-devel] Re: [Mesa3d-dev] Three concepts for changing the way video works in Linux

[Alan C. <al...@lx...>]

On Sul, 2004-03-14 at 16:29, Jon Smirl wrote:
> You're right that DRM is not tied to the OpenGL API. But what about things like
> memory management of the video RAM and AGP space? Right now that is happening
> inside of the OpenGL libraries.

Much of it has to. The allocation rules vary by card. DRI supports
pretty much everything from "frame buffer only" through "write only
split texture ram with no texture to cross a bank" through to some of
the intel stuff where everything is in AGP space and main memory becomes
video ram on demand.

> Also note that the DRM interface is different for each board. There is no 'draw
> circle' entry point to DRM. So it is possible to implement another API on top of
> DRM but you will need to coordinate memory management and do a different version
> for each DRM driver.

You do anyway. Memory management for the DRM internals is non trivial,
especially to do securely with shared texture memory pools. At best the
DRM driver can deal with basic questions like "now I have the lock back
what memory do I need to consider invalid". 

Alan