Comment # 17 on bug 1089287 from Dr. Werner Fink

(In reply to Fabian Vogt from comment #16)
> I tried to debug this further, the issue is that sddm doesn't actually
> create a session and set a controlling tty. That's currently done by the X
> server.
> This explains why -keeptty does not work and also why loginctl doesn't show
> vt7.
> 
> sddm only calls setsid for the user session, but as there's no X server in
> the user session it doesn't get a controlling terminal either.
> 
> While looking at lightdm to check how it's done properly I noticed that it
> has the exact same issue.
> 
> What does sddm need to do to work with -keeptty?

How does gdm solve this problem?  AFAICR the -keeptty option should avoid
deteaching the controlling terminal by the X server. But here it is not
connectted to the tty7 anymore:

 ps aux | grep bin/
 root      2176  0.5  0.8 499472 70108 ?        Sl   Jul02  60:21 /usr/bin/X
-nolisten tcp -keeptty -auth /run/sddm/{ac43390f-4fcf-4711-b111-99f6c749eb82}
-background none -noreset -displayfd 17 -seat seat0 vt7

somehow strange. It seems that the option -keeptty does not work here. The
question rises if this is how sddm/lightdm are starting the X server and how
this differs from the method used by gdm.