Automatically choosing a VT for DRM compositor?

Pekka Paalanen ppaalanen at
Tue Oct 24 06:33:27 UTC 2017

On Mon, 23 Oct 2017 14:37:37 -0500
Matt Hoosier <matt.hoosier at> wrote:

> It would be nice for non-session uses of Weston (embedded systems) if
> the controlling TTY didn't need to be manually supplied.
> Has anybody suggested using something like VT_OPENQRY in the
> weston-launcher code to pick a TTY if one wasn't manually given? (Or
> if that's too auto-magic for taste here, then only do that if a
> specific command-line option is supplied.)


I do not recall such proposals. I'd like to hear more about your use

Do you mean in 'weston-launch' specifically, or in all the launcher

If for 'weston-launch' specifically, then I'd like to ask why you want
that instead of a logind service?

I've been hoping there would be no need for new development on
weston-launch. It is sensitive code, being setuid root. It seems it
cannot be nicely generalized to support all libweston-based compositors.

What is the launching context in you use case? E.g.
- manual login, type 'weston' in VT
- type 'weston' in a terminal window
- launching weston from a systemd system unit
- launching weston from a systemd user unit
- something else?

What is the "non-session" use exactly? Why do you not care which VT
weston will occupy in that case?

I haven't checked recently, but I have a feeling that Weston is not
expecting to be spawned on a currently inactive VT, so that might need
fixing as well.

> The closest I can find to a question about this topic prior on the
> mailing list is
> That change was never adopted, but it doesn't look like the use of
> VT_OPENQRY has anything to do with Kristian's objections at the time.

Picking the first free VT sounds fine to me, but do display servers
actually do that on their own or does e.g. the graphical login manager
do it for them? Or rather, when and who usually picks the VT?

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