Differences in xrandr between Slackware and multiple distros

mostlyharmless · 01-02-2015, 11:38 AM

So, I'm trying to get my two graphics cards to play nice together and find that most distros, including Slackware, can't seem to get it right... or rather I can't get it right.

I have a Quadro K2000 and an AMD HD7970, each with their own monitor, with an Intel I7 that does not have integrated graphics. The AMD card is in the primary slot.

If I boot the live disk of Knoppix 7.4 or Kaos 2014, the system boots successfully and I get this output in the terminal:

Code:

xrandr --listproviders

Provider 0: id: 0xb3 cap: 0xf, Source Output, Sink Output, Source Offload, Sink Offload crtcs: 6 outputs: 4 associated providers: 1 name:radeon
Provider 1: id: 0x66 cap: 0x7, Source Output, Sink Output, Source Offload crtcs: 4 outputs: 3 associated providers: 1 name:nouveau

Typing

Code:

xrandr --setprovideroutputsource 1 0

makes both screens work together, allowing dragging from one screen to the other

The boot line from kaos is

Code:

initrd=/kdeos/boot/x86_64/kdeosiso.img kdeosisolabel=KAOS_20140820 vga=0x3d2 video=1920x1080  lang=en_US keytable=us layout=us nonfree=no xdriver=no i915.modeset=1 nouveau.modeset=1 radeon.modeset=1

Contrast the situation with Linux Mint 17 live, which only detects the radeon card, but boots... and a handful of other distros, such as openSUSE 13.1, which black screens on live boot, as do some other distros (newest Ubuntu for example). Knoppix 7.4 has the same output as Kaos, but without the explicit modeset kernel commands. So clearly it is possible, and without specifying the modeset kernel commands too.

Slackware 14.1 and now -current (I've been playing around with this for a while) only detects the primary radeon card, just like Mint. However, if I explicitly make a 90-serverlayout.conf file under /usr/share/X11/xorg.conf.d and explicitly make [Screen] and [Device] sections as in https://wiki.archlinux.org/index.php/multihead, then I get two screens, but cannot drag from one to the other, and there's other slightly weird behaviour too.

In fact, if you run xrandr --listproviders in Konsole in primary screen it will only show the radeon card, as before, but running in the secondary only shows the nouveau or nvidia driver, never both.

I have reviewed the Xorg.0.log file any number of times but the etiology of the difference in hardware detection eludes me.

Planning on a reinstall soon, in another attempt to get this all to work, but I'd rather not if I can, and I'd like to stick with Slackware in any case. Any ideas as to why some distros live versions work out of the box, some don't even boot, and most importantly why I can't get Slackware to handle the hardware like Kaos or Knoppix?

ferrari · 01-11-2015, 03:11 PM

It will likely come down to the X.Org version employed in the respective dirstros. For example, openSUSE 13.1 is using X.Org X Server 1.14.3.901 (1.14.4 RC 1), and I think openSUSE 13.2 is using 1.16.1

A quick search shows Slackware 14.1 uses 1.14.7, so maybe worth considering Slackware 14.2?

mostlyharmless · 01-12-2015, 12:09 PM

Thanks for responding. Yes, good theory. I've been playing around with it some more. The latest Slackware -current has Xorg 1.15.2, which, without any configuration files, fails. Xorg -configure as root yields "Number of created screens does not match number of detected devices" with a configuration failure.

I have determined that xrandr only shows the one provider in each screen in Slackware because in order to get X to detect both cards and actually run with the multi-monitor setup, I specified two screens in 90-serverlayout.conf.

There must be some way to list the monitors and cards so that X will run but with only one Screen section.

The question then would remain:

What is the xorg.conf file that will yield the equivalent of running xrandr --setprovideroutputsource 1 0, assuming both providers are detected on one screen? Even if Slackware updates xorg to 1.16.* at some point soon, I'll still have to figure that out.