Red Hat Bugzilla – Bug 840913
Control-center allows me to active 3rd display although the graphic card/drive support only 2
Last modified: 2016-09-19 22:14:53 EDT
Description of problem:
In System Settings - Displays I'm able to active 3 displays (1 laptop built-in, 2 external), but my graphic card/drive supports only 2 displays, so it causes X server freeze
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Have 2 external displays connected + 1 laptop built-in
2. In System Settings - Displays click to the inactive one and activate it
X server freezes
Any message that I'm not able to do that, it's not supported or something like that; no freeze
We can't stop the X server freezing, it just shouldn't freeze and give us back an error instead. Reassigning to nouveau.
can you supply /var/log/Xorg.0.log for this machine?
is it reproducible with latest RHEL7 nightly?
On my ThinkPad T520 with Intel GPU and the latest RHEL7 nightly I'm able to activate 3 displays at the same time (while only 2 are actually supported) via gnome-control-center and the X server won't crash. However, a window with the current session nested inside will appear and cause some glitches and artifacts. No error message is shown either. I also see no errors in Xorg logs.
*** Bug 911086 has been marked as a duplicate of this bug. ***
Created attachment 851184 [details]
I confirm there is no crash on latest RHEL7.
I have HD3000 GPU, T420s laptop display + external monitor setup. When I connect second monitor and enable it in control-center I got following error:
"Failed to apply configuration: %s
Timeout was reached"
You can see this on the screenshot.
control-center shows second monitor miniature as enabled, but monitor stays actually off.
There is an artifact in Gnome Shell: Left half of left screen is rendered in the center of middle screen. Going into activities hides artifact temporally, going back shows it again. This seems to be like compositing issue.
No error in Xorg.log.0, dmesg or journalctl.
There are no rendering artifacts in KDE nor crash either.
But System Settings Display behavior is also buggy. It shows second external monitor as enabled and doesn't warn user about unsupported by HW setup.
I see 2 problems here:
1) Integration between Xorg and both Gnome/KDE desktops for unsupported screen configurations.
2) gnome-shell or DRM (kernel) rendering/compositing issue.**
**TODO: File separate bug, after we decided which component is buggy.
(In reply to Martin Holec from comment #7)
> 1) Integration between Xorg and both Gnome/KDE desktops for unsupported
> screen configurations.
Can't speak for the kernel/driver part, but on KDE/Gnome side we can detect maximum number of configured screens by counting available CRTCs, which is exposed via XRandR extension.
Could you file a bug for KScreen if you think we should handle the situation there too?
Can I get the output of 'xrandr --verbose' from the original reporter's configuration? The X server should just reject invalid configurations, so it's possible the driver is advertising something it shouldn't.
Created attachment 853935 [details]
New monitor is on HDMI2.
The xrandr output there correctly reports that only two CRTCs are available, so to the extent that this is possible in the UI, it's a Gnome bug.
This was easily fixed in KDE, see: https://bugzilla.redhat.com/show_bug.cgi?id=1056251
I don't like to see Gnome falling behind. Can you fix Control Center handling of unsupported screen configurations?
This was easily fixed in KDE KScreen. Could you do same for Control Center?
I can confirm the fix in scratch builds. If I activate the 3rd monitor, the Apply button becomes insensitive, but also preferably I'd like to see some msg. clearly stating that current configuration is unsupported.
(In reply to Jiri Koten from comment #18)
> I can confirm the fix in scratch builds. If I activate the 3rd monitor, the
> Apply button becomes insensitive, but also preferably I'd like to see some
> msg. clearly stating that current configuration is unsupported.
Same here. Please push it to repository ASAP.
Updating control-center is enough on RHEL7. I think we can push it without updated gnome-desktop3.
This request was resolved in Red Hat Enterprise Linux 7.0.
Contact your manager or support representative in case you have further questions about the request.