Created attachment 1945142 [details] Journal for the boot of Fedora-KDE-Live-x86_64-38-20230218.n.0.iso on bare metal in which I saw the black screen problem twice Description of problem: I booted Fedora-KDE-Live-x86_64-38-20230218.n.0.iso in a QEMU/KVM VM in GNOME Boxes with 3 GB RAM and 3D acceleration disabled using the llvmpipe driver in a F37 KDE Plasma installation. I noticed that Switch User was shown in the Leave menu of the Application Launcher menu in Plasma 5.27.0. The Switch User option had been previously disabled. When I selected Switch User, a black screen occurred. I tried to switch VTs by clicking on ctrl+alt+f2, ctrl+alt+f3 in the Keyboard menu in GNOME Boxes but the VT logins didn't appear. I shutdown the VM. I booted Fedora-KDE-Live-x86_64-38-20230218.n.0.iso from a USB flash drive written with Fedora Media Writer on bare metal with sysrq_always_enabled on the kernel command line. When I selected Switch User, a black screen occurred with a mouse cursor that I could move for a second then froze. I pressed sysrq+alt+e to stop all processes which restarted Plasma. The journal around the time of the black screen showed sddm-helper exited with the error code 5 and sddm "Couldn't initiate jump to VT 0: No such device or address" I didn't think there was a VT 0 which might be the reason for the problem. Feb 19 15:51:15 systemd[1]: Started session-c1.scope - Session c1 of User sddm. Feb 19 15:51:15 audit[2754]: USER_START pid=2754 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:session_open grantors=pam_unix,pam_systemd acct="sddm" exe="/usr/libexec/sddm-helper" hostname=localhost-live addr=? terminal=/dev/tty1 res=success' Feb 19 15:51:15 sddm-helper[2754]: pam_unix(sddm-greeter:session): session closed for user sddm Feb 19 15:51:15 audit[2754]: USER_END pid=2754 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:session_close grantors=pam_unix,pam_systemd acct="sddm" exe="/usr/libexec/sddm-helper" hostname=localhost-live addr=? terminal=/dev/tty1 res=success' Feb 19 15:51:15 audit[2754]: CRED_DISP pid=2754 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 msg='op=PAM:setcred grantors=pam_permit acct="sddm" exe="/usr/libexec/sddm-helper" hostname=localhost-live addr=? terminal=/dev/tty1 res=success' Feb 19 15:51:15 systemd[1]: session-c1.scope: Deactivated successfully. Feb 19 15:51:15 sddm[1426]: Auth: sddm-helper exited with 5 Feb 19 15:51:15 sddm[1426]: Couldn't initiate jump to VT 0: No such device or address Feb 19 15:51:15 systemd-logind[1241]: Session c1 logged out. Waiting for processes to exit. Feb 19 15:51:15 systemd-logind[1241]: Removed session c1. I'll attach the journal for the boot in which I saw the black screen problem twice with the same sddm errors. I'm not sure if Switch User was intended to be enabled again. Plasma might have been trying to start sddm on VT 0 which didn't exist, or the problem might be with sddm. Version-Release number of selected component (if applicable): plasma-workspace-5.27.0-3.fc38 sddm-0.19.0^git20230201.3ee57e9-2.fc38 qt5-qtbase-5.15.8-5.fc38 kf5-plasma-5.103.0-1.fc38 How reproducible: Selecting Switch User resulted in a black screen 4/4 times Steps to Reproduce: 1. Download Fedora-KDE-Live-x86_64-38-20230218.n.0.iso from https://koji.fedoraproject.org/koji/buildinfo?buildID=2154783 2. boot Fedora-KDE-Live-x86_64-38-20230218.n.0.iso in a QEMU/KVM VM in GNOME Boxes with 3 GB RAM and 3D acceleration disabled or on bare metal 3. in the VM case, I disabled automatic login from sddm in System Settings. I'm not sure if this is needed. 4. Select the Application Launcher menu in the lower left corner of Plasma 5.27.0 on Wayland 5. Select the Leave menu 6. Select Switch User Actual results: Selecting Switch User in Plasma 5.27.0 in F38 resulted in a black screen with sddm errors Expected results: sddm would appear normally Additional info: Switch User doesn't appear in the Leave menu in Plasma 5.27.0 of my F37 KDE Plasma installation.
I reported this problem at https://bugs.kde.org/show_bug.cgi?id=466118 There's a report about user switching problems involving two users at https://github.com/sddm/sddm/issues/1660 Selecting Switch User resulted in a black screen 6/8 times. I had switched to VT2 in VMs and logged in as the liveuser user before selecting Switch User in the two cases when the lock screen appeared instead of a black screen.
Proposed as a Blocker for 38-final by Fedora user mattf using the blocker tracking app because: Selecting Switch User in Plasma 5.27.0 in the Fedora 38 KDE Plasma live image Fedora-KDE-Live-x86_64-38-20230218.n.0.iso resulted in a black screen with sddm errors in VMs and on bare metal, and nothing appeared when I tried to switch to another VT. This problem happened unless I had previously switched to another VT and logged in as the liveuser user in which case a lock screen was shown. The Fedora 38 Final blocker criterion "User switching must work using the mechanisms offered (if any) by all release-blocking desktops in their default configuration." might be violated. https://fedoraproject.org/wiki/Fedora_38_Final_Release_Criteria#User_switching
IIRC, we intend to specifically disable user switching in KDE in Fedora because it's known not to work very well. I guess what changed is that disablement got lost?
(In reply to Adam Williamson from comment #3) > IIRC, we intend to specifically disable user switching in KDE in Fedora > because it's known not to work very well. I guess what changed is that > disablement got lost? Switch User was disabled for https://bugzilla.redhat.com/show_bug.cgi?id=1929643 in kde-settings-34.5-1.fc34 https://bodhi.fedoraproject.org/updates/FEDORA-2021-a526beb5e7 The lines disabling user switching appear to have been removed by https://pagure.io/fedora-kde/kde-settings/c/c48b87a6c5447b9c9b2febe96bf94feae9ad5183?branch=rawhide in kde-settings-38.0-1.fc38 https://koji.fedoraproject.org/koji/buildinfo?buildID=2150810 Thanks.
This is technically an sddm bug, though it'll be "fixed" by disabling fast user switching again in KDE Plasma.
Revert applied: https://pagure.io/fedora-kde/kde-settings/c/abdb7005d5e5d8b3ccdc84ffab5bd37b0973d36c Packages building: * F39: https://koji.fedoraproject.org/koji/taskinfo?taskID=97780917 * F38: https://koji.fedoraproject.org/koji/taskinfo?taskID=97780935
+3 in https://pagure.io/fedora-qa/blocker-review/issue/1040 , marking accepted. Also proposing as a Beta FE in case the update doesn't make it before freeze kicks in.
the update did get in under the freeze, so this ought to be resolved now. Matt, can you confirm the switch user option is gone in latest updates? Note this may possibly only affect freshly created user accounts. +4 Beta FE in https://pagure.io/fedora-qa/blocker-review/issue/1040 , so marking as accepted just in case this isn't actually fixed yet.
(In reply to Adam Williamson from comment #8) > the update did get in under the freeze, so this ought to be resolved now. > Matt, can you confirm the switch user option is gone in latest updates? Note > this may possibly only affect freshly created user accounts. > > +4 Beta FE in https://pagure.io/fedora-qa/blocker-review/issue/1040 , so > marking as accepted just in case this isn't actually fixed yet. Switch User isn't shown in the Leave menu of the Application Launcher menu in Fedora-KDE-Live-x86_64-38-20230221.n.1.iso. Thanks.
Awesome, let's close this then.