[SOLVED] Plasma 5 + DRI2 = impossible?

Basic-Master · 2015-06-18 13:40:44

Hi,

I have a Radeon 8790M in combination with an embedded Intel graphics card in my notebook and I've been struggling to get 3D acceleration working properly. Using the proprietary AMD driver didn't work out well at all, in fact I find the open-source radeon driver much more stable than the official AMD driver. I used to use DRI_PRIME as described in the wiki to start graphics-hungry applications with DRI1, but whenever I have the KDE compositor enabled, I usually get black windows and I don't want to turn off my compositor every time I want to run a game for example. Adding a KWin rule to disable compositing doesn't fix this behavior either, and if I use DRI2, this problem usually doesn't show up and my 3D applications generally seem to run smoother as well.

So instead of DRI1 I wanted to go with DRI2 and it does work perfectly well with XFCE, but in 4 out of 5 login attempts Plasma 5 (or rather kwin) crashes while KDE is starting up. I used "X -configure" to generate a new Xorg configuration, so both the intel and ati drivers are loaded. If I disable the discrete AMD graphics card (i.e. if I don't explicitly load it via my Xorg configuration), KDE loads up just as I'd expect, but I don't understand why I can use XFCE without problems with the same X configuration (with compositing enabled) while Plasma fails to start, even if I switch back to XRender or disable the compositor completely. I also tried to use a clean home directory to ensure this isn't caused by a faulty KDE configuration, but that didn't fix anything either - KDE just gets stuck at the splashscreen again.

Well, earlier I also tried to enable DRI3 for testing purposes and recompiled mesa, xf86-video-intel and xf86-video-ati with the proper DRI3 flags, but in my case Xorg segfault'ed whenever I tried to start it. So I'd rather like to stick with DRI2 now as I seem to get the best performance with it. Of course now I'm using the stock Arch mesa, Intel and AMD packages again.

Does anyone else use a DRI2 configuration with two graphics adapters? I'd really like to figure out why this is happening and how I can fix it. I can share my Xorg configuration and/or additional logs if anyone is interested, just let me know.

Any help on this topic is appreciated!

Last edited by Basic-Master (2015-06-20 18:02:39)

Lone_Wolf · 2015-06-19 12:51:53

You appear to be confusing the Xorg Composite extension and using a compositing window manager.

XFCE doesn't use a compositing window manager, it only uses the xorg Composite extension.
KWin IS a compositing window manager.

You are also confusing DRI1 / DRI2 & DRI3 with using DRI_PRIME=1 <some command> .

DRI_PRIME=1 <some command> tells linux to run <some command> using DRI_PRIME .

Please read what i posted carefully, then rewrite your post to clarify your problem.

Xabre · 2015-06-19 14:08:37

I have a similar setup, and the only real advice I can give you is: using discrete GPU for Plasma (or any other DE) is an overkill and a waste of power (especialy given it is a laptop). Intel's IGP which you have on that laptop is more than capable of running anything that Plasma throws at it.
DRI_PRIME, using discrete Radeon that is, makes sense only for a specific GPU-hungry apps, like games or video rendering in general.

Last edited by Xabre (2015-06-19 14:09:52)

Basic-Master · 2015-06-20 18:01:12

Ah okay, thank you Lone_Wolf for this clarification. But wouldn't KWin use the same Xorg composite extension if I set its acceleration method to XRandr? I don't quite understand where the diference is.

Anyway, meanwhile I've managed to get everything sorted by switching over to mesa-git and xf86-video-intel-git. I recompiled both packages with --enable-dri3 set, the latest versions seem to work nicely with my Intel and AMD graphics adapters. xf86-video-ati is NOT required for DRI3, mesa seems to pass it through directly via DRI3, hence my prior attempt to load it via my own xorg.conf failed. DRI3 works even better than DRI2, so I'm pretty happy now. Also, while I didn't have to use DRI_PRIME=1 with DRI2, this appears to be required for DRI1 and DRI3. I figure DRI2 uses both renderers at the same time, which Plasma cannot handle properly (I could verify this by checking the glxinfo output).

Too bad Arch's stock packages aren't compiled with DRI3 enabled, but I read elsewhere that this wasn't an Arch decision - no idea why though, after all DRI3 is not active on load unless you explicitly tell the Intel Xorg driver to enable it.

Xabre, I know it's pretty pointless to use discrete GPUs only for Plasma (and you actually need to do this if you go with the proprietary AMD drivers), but it's a must-have if you want to run any 3D-intense application on your notebook as I do.

Lone_Wolf · 2015-06-22 11:08:49

Basic-Master wrote:

Ah okay, thank you Lone_Wolf for this clarification. But wouldn't KWin use the same Xorg composite extension if I set its acceleration method to XRandr? I don't quite understand where the diference is.

Compositing window managers REQUIRE a running Xorg Composite extension to do their job, regardless of which acceleration/render method they use.
Xorg Composite extension also has functionality that is used by non-composting window managers.

Basic-Master wrote:

Anyway, meanwhile I've managed to get everything sorted by switching over to mesa-git and xf86-video-intel-git. I recompiled both packages with --enable-dri3 set, the latest versions seem to work nicely with my Intel and AMD graphics adapters. xf86-video-ati is NOT required for DRI3, mesa seems to pass it through directly via DRI3, hence my prior attempt to load it via my own xorg.conf failed. DRI3 works even better than DRI2, so I'm pretty happy now. Also, while I didn't have to use DRI_PRIME=1 with DRI2, this appears to be required for DRI1 and DRI3. I figure DRI2 uses both renderers at the same time, which Plasma cannot handle properly (I could verify this by checking the glxinfo output).
Too bad Arch's stock packages aren't compiled with DRI3 enabled, but I read elsewhere that this wasn't an Arch decision - no idea why though, after all DRI3 is not active on load unless you explicitly tell the Intel Xorg driver to enable it.

Mesa-git has DRI3 enabled now since a while, stock mesa should have it soon, maybe 10.6 (now in testing) has it already.
Even if mesa is compiled wtih DRI3, for radeon cards you need xf86-video-ati-git to use DRI3 .
Latest stable xf86-video-ati version, 7.5.0 doesn't support DRI3 .

Arch Linux

#1 2015-06-18 13:40:44

[SOLVED] Plasma 5 + DRI2 = impossible?

#2 2015-06-19 12:51:53

Re: [SOLVED] Plasma 5 + DRI2 = impossible?

#3 2015-06-19 14:08:37

Re: [SOLVED] Plasma 5 + DRI2 = impossible?

#4 2015-06-20 18:01:12

Re: [SOLVED] Plasma 5 + DRI2 = impossible?

#5 2015-06-22 11:08:49

Re: [SOLVED] Plasma 5 + DRI2 = impossible?

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