Black screen after KDE 5 logo (with log)

[Duncan]

Dâniel Fraga posted on Tue, 13 Dec 2016 12:35:22 -0200 as excerpted:

> 	I compiled and installed KDE 5 (Frameworks 5.28.0 and Plasma
> 5.8.4) from scratch succesfuly, but after the SDDM login, there's only a
> black screen with a cursor.
> 
> 	If I start xterm from the console, it appears. What's
> interesting is that I can start fine KDE 4 from the SDDM (only KDE 5
> shows this problem, so my conclusion is that the X and graphics setup
> are fine). I tried to run plasmashell from the console and nothing
> happens:
> 
> Here's the log:

[snip]

The trouble with kde/plasma logs is that they log all kinds of useless 
but alarming looking "noise", at least in terms of user diagnostics 
(individual component devs could arguably get something from it, but 
apparently tend to ignore it as well or a good 2/3 of those messages 
would likely be gone!), without telling you much of /anything/ about the 
/real/ problem!

Obviously I've run into issues and encountered a similarly useless log 
here, before. =:^(

More practically...

Generally, what I've found to be the problem when all I get is a blank 
screen, is that plasma itself won't start.  Try manually starting 
plasmashell (in the kde4 era it was plasma-desktop, IIRC), and see if it 
at least gives you a different log, with something hopefully useful in 
it.  Or run top/htop or the like and see if plasmashell is already 
running, and try terminating and restarting it, if so.

Talking about htop, or more in general about the plasma startup process 
tree...

Here at least, in htop in tree view, kdeinit5 is the parent process of 
ksmserver (I believe ksm = kde session management, so it's the session 
management server), which in turn is the parent to plasmashell, krunner, 
and kwin_x11, among other processes (ksmserver apparently also starts 
various apps in the startup dirs).  Besides ksmserver, kdeinit5 is also 
the parent of kded5 and klauncher.

Launched separately or otherwise reparented to systemd (pid1/init on most 
Linux desktops these days, I suspect, tho on gentoo anyway, it's 
optional, with sysv-init/openrc still the default), I have kuiserver5, 
kactivitymanagerd, kaccess, kglobalaccel5, and start_kdeinit.

You may wish to compare that to what's running in your case, to see 
what's missing.

Tho I should mention that I do a text mode login, and (indirectly via my 
own script) run startx from there, which in turn runs startkde after 
starting up X.  No sddm/*dm graphical login setup here.  So your kde/
plasma related process tree may look slightly different, but those are 
all reasonably core kde/plasma5 services, so most of them should be 
running on a healthy plasma5 session, regardless of whether you use a GUI 
login, or text login and do startx, as I do.

One more note.  Another failure mode which I had at one point but that 
doesn't seem to be your problem as the results are a bit different, is 
that kwin (kwin_x11) would get caught in a crash and respawn loop, 
eventually resulting in a little dialog saying it had restarted too many 
times, too quickly.  That was fairly early in the startup process, 
preventing most of the rest of the desktop from coming up, but I did get 
that (borderless of course, due to no kwin) dialog, telling me what 
happened.  The problem back then was a kwin that didn't like my native 
xorg/mesa/linux-kernel opengl setup, and it has long since been fixed.  
I'm mentioning it here primarily in ordered to illustrate that your 
problem should /not/ be with kwin, as the results would be different, so 
you should be able to rule that out.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman