Bug 651776

Summary:	sddm black screen since qt 5.9.4 stabilization
Product:	Gentoo Linux	Reporter:	Simon Siemonsma <simon>
Component:	Current packages	Assignee:	Gentoo Linux bug wranglers <bug-wranglers>
Status:	RESOLVED NEEDINFO
Severity:	normal	CC:	jstein
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Simon Siemonsma 2018-03-27 18:37:29 UTC

After the stabilization of qt 5.9.4 I got a black screen with a mouse pointer instead of the SDDM login screen.
In my logs I find: Auth: sddm-helper exited with 6
Reverting back to the previous qt version solves the problem.

Reproducible: Always

Steps to Reproduce:
1.Upgrade qt to 5.9.4
2.
3.
Actual Results:  
Black screen with mousepointer

Expected Results:  
Greeter windows of SDDM

Comment 1 Jonas Stein gentoo-dev

2018-03-27 18:45:00 UTC

Thank you for the report. Please recompile and *attach* the logfiles,
https://wiki.gentoo.org/wiki/Attach_the_logs_to_the_bug_ticket
and reopen this ticket (Status:unconfirmed).

Also try to get all warnings from stderr and logfiles and attach these too.

Comment 2 Simon Siemonsma 2018-03-30 06:48:22 UTC

From the Arch wiki:
Applications using QML crash or don't work with Qt 5.8

Starting with Qt 5.8, applications that rely on QML (such as SDDM or some KDE programs) may crash or fail to function correctly if they do not have execution privileges under /home or /var (e.g. if these are separate filesystems mounted as 'noexec'). This is a result of the qmlcache feature, which relies on being able to write files out to .cache directories and then execute them. See also BBS thread 222486: sddm-helper crashes.

If you do not want to -- or cannot -- allow such execution privileges, a workaround is to set the following as appropriate in your environment variables:

QML_DISABLE_DISK_CACHE=1

With Qt 5.11 this will be solved.