On Fr, 01.12.17 13:42, Pekka Paalanen (ppaala...@gmail.com) wrote: > > > > This is racy, as the session ID is not really reliably predictable, > > > > and is synthesized in different contexts in different ways, for > > > > example depnding on whether audit is enabled in the kernel it might be > > > > session-1.scope rather than session-c1.scope. > > > > If we could determine the bug doesn't exist anymore, that would be > > > awesome and I could just drop this. > > Hi Lennart, > > taking a step back, the session-c1.scope directive is definitely not > wanted and we should drop it. We should also use a custom PAM name > setup. If we do that, is the service file otherwise good for > guaranteeing: > > - a full user session setup (I presume we want it), specifically > XDG_RUNTIME_DIR being set up > > - running exclusively on a VT that is made current
This really depends on how weston sets up a VT. I really don't know Weston and what it does. > - access to DRM and input devices via logind So, I can't comment on Weston really. Here are brief (and possibly slightly out-of-date, but probably not) notes on how to write display managers with logind: https://www.freedesktop.org/wiki/Software/systemd/writing-display-managers/ > so that all these are already in place by the time the Weston process > is started? > > As you can see from Martyn below, the first issue that prevented Weston > from running was that XDG_RUNTIME_DIR was not set. Furthermore, this > failure did not occur always, sometimes things just worked as we > expected. So, as long as weston runs from a PAM enabled service (and its PAM snippet pulls in pam_systemd) all should be good and race-free: as the PAM session is set up XDG_RUNTIME_DIR will be made available and the systemd --user instance is invoked in the background. What currently is not supported is to run things independently of any session, i.e. run weston as systemd --user service with nothing that creates a session in the first place. In that case XDG_RUNTIME_DIR will not be set up, and no devices are made available to weston... > > > > > +# Set up a full user session for the user, required by Weston. > > > > > +PAMName=login > > > > > > > > Piggy-backing on "login" is a bad idea. "login" is a text tool, and > > > > thus the PAM rules for it usually pull in some TTY specific PAM > > > > modules. YOu shoudl really use your own PAM fragment here, and > > > > configure only the bits you need. > > > > > > > Oh, so could it just be that we needed something other than > > "PAMName=login"? > > What are they key bits in the PAM configuration we must have, and are > there any often used bits we must not have to avoid the race Martyn > describes? well, pam_systemd needs to be pulled in from it, that's the most important thing. A PAM snippet that pulls in pam_systemd means you get a session allcoated in logind, which in turn sets up XDG_RUNTIME_DIR for you. Lennart -- Lennart Poettering, Red Hat _______________________________________________ wayland-devel mailing list wayland-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/wayland-devel
