Hello,
I have been playing with Catalyst on ArchLinux in order to get my Hybrid
Graphics working. Catalyst supports PowerXpress 4.0+ in Linux, so
muxless graphics can work.
It took me some time to get it to work, I had to workaround many stuff.
Here follows:
First thing that I was bothered with is that
/usr/lib/fglrx/switchlib{GL,glx} were missing.
Their purpose is to switch /usr/lib/libGL.so.1 and
/usr/lib/xorg/modules/extensions/libglx.so to either AMD (Catalyst) or
Intel (Mesa and Xorg) libraries.
Each one is called with "intel" or "amd" as an argument, and both must
exit sucessfully with "echo amd" or "echo intel" after getting the job done.
I've managed to "fool" Catalyst by creating dummy files.
#!/bin/bash
echo amd
exit 0
By default, aticonfig --initial will use AMD (Discrete) GPU, so the
current installation seems to be okay. I'll continue with other issues
that can arise later in this mail.
Next major problem is that fglrx will load intel driver, which,
unfortunately can't be installed by default since it depends on
intel-dri, which depends on libgl which is in conflict with
catalyst-utils package (doh). I had to rebuild it without intel-dri
dependency to get this working.
On why intel driver is necesary, I can answer the following:
Most newer hybrid graphics are muxless, they do not have hardware
multiplexer and you can't select on which GPU you want to output.
Instead, Discrete GPU is just wired to Integrated one and is meant only
for Processing while it is on Integrated GPU to display anything passed
from the Discrete GPU. For more information on this term, you may want
to look at DRI PRIME and DMA BUF (An open source solution for this
mess). So in fact, intel driver is needed since it is used for 2D and
stuff, where fglrx only does the encoding/decoding stuff.
How to fix it?
Well, I couldn't think of any nice way to fix this. Debian has their
alternatives system so they can have multiple libGL installed and set
with alternatives. Gentoo does the same with their eselect stuff or
whatever it's called.
Since aticonfig --px-dgpu tells xorg.conf to use Discrete (AMD) GPU, it
also runs /usr/lib/fglrx/switchlib{GL,glx} with "amd" as parameter in
order to "make" /usr/lib/libGL.so.1 and
/usr/lib/xorg/modules/extensions/libglx.so point to AMD provided
libraries. aticonfig --px-igpu would switch to Mesa libGL.so.1 and Xorg
Server libglx.so which are, you know, not present when catalyst-utils
are installed. (Xserver libglx.so is present, but it's useless without
Mesa's libGL.so.1).
On how to solve this I can only think of making another package (part of
Mesa source package) called something like intel-dri-hybrid (which
depends on catalyst-utils and can only be used with it) that installs
Intel DRI drivers and libGL.so.1 into some nonstandard place or just
renamed to something else like libGL-intel.so.1. Also, it would be
necesary to make /usr/lib/fglrx/switchlib{GL,glx} to correctly switch
(symlinks should do it, but carefully) between AMD and Open Source libGL
and libglx.
I haven't done this yet but some may want to use this - not everyone
wants to use Discrete GPU always - especially when on battery. I can say
that power consumption on my laptop has dropped even though I always
disabled Discrete GPU via vgaswitcheroo (radeon driver).
Any comments and suggestions are welcome. I can try to implement
something if necesary, it's just the question if my suggestions are good
enough and will be accepted.
I appologize for any gramatical mistakes.
