X withtout DRI

Corbin Simpson mostawesomedude at gmail.com
Mon May 18 02:33:11 PDT 2009

Olivier Martin wrote:
> Just a little question to clarify my understanding of XServer design ...
>>From the DRI website, I can read this article about "DRI without X" (
> http://dri.freedesktop.org/wiki/DriWithoutX). But is it possible to have a
> 3D-enabled XServer with GLX extension and without DRI extension (and module)
> ?

Yes. You'll still need something to provide the bindings between GLX and 
the kernel/lower-level hardware drivers, though.

> On "Introduction to the Direct Rendering Infrastructure" (
> http://dri.sourceforge.net/doc/DRIintro.html), it says about "XFree86 DRI
> Extension":
>     The XFree86-DRI X server extension is basically used for communication
> between the other DRI
>     components (the X server, the kernel module, libGL.so and the 3D DRI
> drivers).
>     The DRI module maintains DRI-specific data structures related to
> screens, windows, and rendering
>     contexts. When the user moves a window, for example, the other DRI
> components need to be informed
>     so that rendering appears in the right place.
> Does it means any OGL implementation within the server-side must supply a
> DRI module ?
> What about the OGL Mesa library with SW rasterization only ? Does it supply
> a DRI module (for managing a lock on the framebuffer) ?

Yes, Mesa now provides a swrast_dri.so which X can use to provide direct 
rendering to software, as well as AIGLX.

> Is it possible to use Mesa driver with a non-DRI backend in the server-side
> ?

There are non-DRI Mesa drivers, but I do not think that any of them 
interact in the same way with Xserver.

~ C.

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