[arch-general] RFC: Catalyst and Hybrid Graphics

[Robbie Smith]

On 06/02/13 06:45, Armin K. wrote:
> 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.

Definitely sounds useful, as a lot of laptops seem to have hybrid 
graphics these days. Mine has two AMD cards (APU and GPU) so I can just 
use `aticonfig` to switch, but it forces me to use the Catalyst drivers 
(several versions behind too!) as the open-source ones give me a blank 
screen.

Have you had a look at Vi0l0's catalyst-pxp packages in his unofficial 
Catalyst repos[1]? There was some discussion on the "AMD/ATi Bar & 
Grill" thread a few months back about this too.

[1] http://catalyst.apocalypsus.net/repo/catalyst/