first and only X needs to be on tty7

[Lennart Poettering]

On Mon, 05.05.14 11:45, Felix Miata (mrmazda at earthlink.net) wrote:

> On 2014-05-05 12:34 (GMT+0200) Lennart Poettering composed:
> 
> >Felix Miata wrote:
> 
> >>How can I get it to go there and stay there? When starting F21 in
> >>multi-user, logging in on tty3 and running startx, KDE shows up on
> >>tty3, where, as it's currently broken[1], it needs to be killed to
> >>escape it. Ctrl-Alt-BS fails to kill it (in spite of xorg.con*
> >>entries intended that Ctrl-Alt-BS be enabled for that purpose), and
> >>switching to tty3 is unavailable to use Ctrl-C to kill it as can be
> >>done when started from tty3 but running on tty7. The only way out is
> >>logging in somewhere else, or CAD. This shouldn't be.
> 
> >>[1] https://bugzilla.redhat.com/show_bug.cgi?id=1092852
> 
> >To get the device permissions right startx can only "upgrade" a text
> >session to a graphical one,
> 
> There is a relatively recent change, as it used to be that the first
> X instance would always start on tty7 no matter how started. I still
> have a DM running there if in graphical target.

It's has been that way since Fedora adopted systemd, which was in F15 or
so IIRC? That makes 3.5y or so...

On Fedora tty1 is the graphical login, since a long time.

> What is this permissions business? IOW, what search terms would lead
> me to an explanation of the changes, or at least a non-simplistic
> but not overly detailed why they occurred?

Dunno, it's about making sure logind knows about your session and on
which VT it is, so that switching to/from it works correctly, and so
that we can managed access to your audio cards and similar properly. And
since very recently even access to input and gfx devices is managed by
logind, so this becomes even more important.

> > it cannot open a new VT.
> 
> Why?

Because you'd have to register that new VT with logind, and there's no
way currently to do that, since creating a session is a one-way street,
and you cannot create another session from an existing one, without
involving some background process that is not part of any session. And
nobody wrote such a daemon yet.

> > Hence if you want X
> >to show up on session N, then you need to start it from ttyN... Note
> >that only tty1-6 get logins by default, but you can configure that with
> >NAutoVTs= in /etc/systemd/logind.conf.
> 
> That sounds like a method that will prevent a DM from running on the
> same tty as startx would as a first and only X session, as if that
> hasn't already happened. OT, reading that man page, is setting it 0
> how to revert from auto spawning to keeping gettys running on all of
> tty1-6 as before systemd existed?

I cannot parse this.

Lennart

-- 
Lennart Poettering, Red Hat