SUMMARY: SDDM presents a 1024/768 logon screen on KVM guests (when set to use Wayland), ignoring any previously chosen screen size. After logon, Plasma uses the size set in System Settings > Display and Monitor. Originally encountered in Fedora38: https://bugzilla.redhat.com/show_bug.cgi?id=2196435 but can be reproduced in Neon Unstable STEPS TO REPRODUCE: Switch SDDM to use Wayland by copying: [General] DisplayServer=wayland GreeterEnvironment=QT_WAYLAND_SHELL_INTEGRATION=layer-shell InputMethod= [Wayland] CompositorCommand=kwin_wayland --no-global-shortcuts --no-lockscreen --inputmethod maliit-keyboard --locale1 as given in https://bugzilla.redhat.com/show_bug.cgi?id=2196435#c1 into /etc/sddm.conf Configure your chosen screen size, logout or reboot.... OBSERVED RESULTS: You get a 1024/768 size SDDM logon screen. (It does not seem to matter whether you are using QXL or Virtio video or whether you select an X11 or Wayland session.) EXPECTED RESULTS: Depends. In a simple case with a single screen, setting the screen size in System Settings > Display and Monitor should set the size SDDM uses. Manually adding width and height to the CompositorCommand CompositorCommand=kwin_wayland --no-global-shortcuts --no-lockscreen --inputmethod maliit-keyboard --locale1 --width 1440 --height 900 should (probably?) act as a workround. SOFTWARE/OS VERSIONS Neon Unstable Plasma: 5.27.80 Frameworks: 5.240.0 Qt: 6.6.0 ADDITIONAL INFORMATION With X11, you can set the preferred mode manually by creating a /etc/share/X11/xorg.conf.d/50-monitor.conf containing: Section "Monitor" Identifier "Virtual-0" Option "PreferredMode" "1440x900" EndSection Section "Monitor" Identifier "Virtual-1" Option "PreferredMode" "1440x900" EndSection If you are using QXL video, then SDDM picks up the "Virtual-0" config, if Virtio then the "Virtual-1" one (although this may be shown as "Red Hat, Inc. QEMU Monitor" under System Settings > Display and Monitor) Ref: https://bugs.kde.org/show_bug.cgi?id=420169#c8
You need to synchronize the user settings to sddm in the sddm settings. This is not something that's currently done automatically
(In reply to Zamundaaa from comment #1) > You need to synchronize the user settings to sddm in the sddm settings. This > is not something that's currently done automatically In System Settings > Startup and Shutdown > Login Screen (SDDM) and Apply Plasma Settings? On Neon Unstable, this inserts some "themeing" information into /etc/sddm.conf.d/kde_settings.conf. I don't think there's anything there about screen size. If I logout/reboot, I still get the 1024/768 logon screen. This does seem related to having "DisplayServer=wayland" (as is set in F38), reopening if that's OK....
Yes. It doesn't only add theming settings to that config, but it also copies KScreen configs to the sddm user directory (so into /var/lib/sddm/.local/share/kscreen) that KWin is then supposed to pick up. If it does copy those files for you but it still doesn't set the correct mode, then maybe something is broken specifically for virtual machines
(In reply to Zamundaaa from comment #3) > ... so into /var/lib/sddm/.local/share/kscreen ... That's cheating! It's hidden folder! 8-) > ... If it does copy those files for you but it still doesn't set the correct mode ... Looks like I've got two json files under /var/lib/sddm/.local/share/kscreen/output The info, for both Virtual-0 and Virtual-1, looks similar to that in my: /etc/share/X11/xorg.conf.d/50-monitor.conf > ... then maybe something is broken specifically for virtual machines ... I've only tried this on VMs, so yes it could be specific. Let me try moving the VM to a different host
Created attachment 161794 [details] kscreen/output - Virtual-0 (QXL)
Created attachment 161795 [details] kscreen/output - Virtual-1 (Virtio)
Created attachment 161796 [details] SDDM screen - As seen when using X11 Without any sddm.conf setup, maybe falling back to X
Created attachment 161797 [details] SDDM screen - As seen with Wayland and QXL video A corner of the screen anyway...
Created attachment 161798 [details] SDDM screen - As seen with Wayland and Virtio video Same corner, slightly larger logon screen...
Created attachment 161799 [details] User Session - After logging on with X11 The full 1440/900 screen size...
Created attachment 161800 [details] User Session - After logging on with Wayland and Virtio Video Screen size for both X11 and Wayland has been set to 1440/900 in system settings - and seems to work
(In reply to tagwerk19 from comment #4) > ... Let me try moving the VM to a different host ... That was far messier than I had expected but I've now got a consistant setup; Fedora 38 KVM host with Fedora 38 (plus Neon Unstable) guests. The behaviour changes and seems to point to something VM related. If SDDM is configured for Wayland and VM set up with QXL video, the SDDM screen is 1024/768. With Virtio video, the screen is "nearly" 1440/900, not full screen but the aspect ratio looks better. I've attached the kscreen/output files and some screenshots of (corners of) the SDDM screen: With SDDM using X, with it using Wayland and QXL and Virtio video, and after logon, with X11 and Wayland Virtio.