Ignatios Souvatzis <ignatios@cs.uni-bonn.de> writes:

> 
> And any X server newer than a few years supports the
> MIT-SHM-Extension. It allows knowledgable clients which are on the
> local machine two write directly into the graphics board RAM in a
> controlled manner (_if_ the graphics board RAM is mapped into the
> CPU's memory space).

No; it just shares an image or pixmap buffer.  You do *not* get access
directly to the frame buffer.  (The `DGA' extension in later versions
of XFree86 do this, mainly to speed up Quake, but I don't know how
portable the code is to other hardware architectures.  At any rate, I
don't think that's what he was asking for.)

MIT_SHM is sufficient for most video applications.  However, if your
problem involves sending a lot of X requests, then no, we don't
currently have a solution.  It would be cool if someone added a shared
memory request/event buffer, though.  (I believe this was one of the
big performance wins with X in later versions of HP-UX.)