> Does anyone know what the advantages/disadvantages of having an irq for a video
> card are?
In general: No advantage. Most of the time, the video card justs listens
to what is written into its framebuffer and displays it. More advanced
cards do accept simple commands that they can perform itself. (Draw lines,
fill polygons, etc.) Very advanced cards do fullfill complicated tasks and
signal that they are ready and wait for new tasks/data by an interrupt. 3D
chips can be considered as very advanced.
I have no idea, if some of the accelerated XFree86 servers make use of
interrupts, but I guess so. The Glide library and maybe also the MesaGL
(OpenGL clone) could profit, too. But as Unix software tends to be
portable and interrupts aren't, I'm not sure.
Kurt Garloff, Dortmund
<K.Garloff@ping.de>
PGP key on http://www.student.physik.uni-dortmund.de/homepages/garloff