> Try logging into a non-GNOME Xorg session on Workspaces > if you can. Then use the 'xrandr' command to set a mode > to turn on one of the unused virtual monitors. If that > causes the DCV client to go blank then we have proven > it's not mutter's fault.
I did test that with a Cinnamon session and confirmed it. I basically did: xrandr --output VNC-output-1 --auto and it immediately goes to a blank screen OK, so saying out loud my understanding of this issue so far, so as to check it's correct. The problems are: - Fractional scaling is supported in RandR 1.3 or newer - Xdcv reports its RandR version is 1.6, but when you try to use fraction scaling it errors (error id 2) - The corruption bug 1924689 may be caused by the fractional scaling patch (or a side effect of the "error id 2"?) - Xdcv is reporting a bogus refresh rate - There's a "config history" issue identified by Mustafa in comments #26 and #30 What we've been doing now to try to narrow it down is: A - The "Zero Hz" fix is basically loosening mutter to accept zero-Hz, as this is the bogus refresh rate being reported by Xdcv B - vv4 fix = no fractional scaling + "zero Hz" fix C - vv5 fix = re-adds fractional scaling + "zero Hz" fix And out of it, we've confirmed in local VM / Workspaces tests that 1 - Without fractional scaling patch (vv4) / with fractional scaling disabled, we can't reproduce the "Failed to restore previous configuration: Invalid mode" / "Impossible to set scaling on crtc" errors 2 - The "Zero Hz" fix causes a side-effect of enabling the unused monitors (tbd if this is a bug) 2a. If you manually disable 3 monitors (keeping only one) and then try to apply / revert 200% scale, it errors [1] and sets resolution back to 800x600 3 - When enabling unused monitors in Workspaces, we get a blank screen (which I've confirmed through cinnamon / xrandr that it must be a problem with the Workspaces client when enabling a monitor) For the "zero Hz" problem, if I understand correctly, it is a bogus issue without a noticeable impact in usage. On the other hand, due to the "zero Hz" fix introducing problems 2 and 2a above, I'm skeptical on validating that avoiding fractional scaling fixes our issue (item 1 above). If the "zero hz" issue is really just bogus, should we try a "vv6" build completely disabling fractional scaling for the Xdcv use case (on apply and revert), but not including the "zero hz" fix? This way we would be able to validate item 1 above (even if we see the zero hz bogus messages, which we can ignore for now). If this succeeds, we can investigate the item 3 above separately, so we can then re-introduce the "zero hz" fix. [1] https://pastebin.ubuntu.com/p/Xtyfvb3CV2/ -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/2020782 Title: Xdcv: Changing display scale setting and reverting it fails To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2020782/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
