Re: OpenGL-based framebuffer concepts

["D. Hazelton" <dhazelton@enter.net>]

On Saturday 03 June 2006 06:31, Jon Smirl wrote:
> On 6/2/06, D. Hazelton <dhazelton@enter.net> wrote:
> > Actually, Jon, Dave is thinking like I am in that the DRI drivers needs
> > to be loaded for use. Rather than forcing applications to include all
> > that code the userspace daemon can be configured to load the DRI driver
> > and provides the userspace interface to the system. Using a daemon for a
> > simple task, like modesetting, is idiotic - but using the daemon to
> > provide userspace with full access to acceleration (the Kernel drivers
> > only provide the backend for the acceleration. The userspace side
> > actually provides the code that manages it all) without needing to have
> > to worry about loading and initializing the dri drivers provides a method
> > for anything from a scripting language to a full compiled application
> > easy access to the acceleration.
>
> You are confused about this. Nobody wants to change the way DRI and
> DRM work, it would take years of effort to change it. These are shared
> libraries, it doesn't matter how many people have them open, there is
> only one copy in memory.

Exactly.

> Applications don't 'include' all of the DRI/DRM code they dynamically
> link to the OpenGL shared object library which in turns loads the
> correct DRI shared library. The correct DRM module should be loaded by
> the kernel at boot. You can write a 10 line OpenGL program that will
> make use of all of this, it is not hard to do. User space has always
> had access to hardware acceleration from these libraries.

Yes, but there are userspace *drivers* that have to be loaded for that code to 
work properly. By providing the daemon no program needs to worry about 
loading those drivers.

> We have not been discussing DIrect Rendering vs indirect (AIGLX). It
> will be up to the windowing system to chose which (or both) of those
> model to use. The lower layers are designed not to force that choice
> one way ot the other.
>
> Dave wants to load the existing X drivers into the daemon, not the DRI
> libraries. Other than using them for mode setting there isn't much use
> for them. I have asked him where he wants things like blanking, cmap,
> cursor and he hasn't said yet. Those functions are tiny, ~100 lines of
> code.

Stuff like that would probably be best left to small userspace helpers, or 
potentially 1 userspace helper that figures out what to do based on what the 
name is that's given to the link.

DRH