On Tue, Sep 22, 2015 at 12:32:25PM +0200, Lennart Poettering wrote: > On Tue, 22.09.15 10:11, Daniel P. Berrange (berra...@redhat.com) wrote: > > > > And most importantly: the entire protocol use by sysvinit via > > > /dev/initctl is deeply flawed, since it sends messages over > > > /dev/initctl that are not a divisor of PIPE_SIZE in length. Thus, if > > > PID 1 didn't read messages quick enough the messages queued could be > > > half-written and be partially interleaved with another client's > > > messages, and there is no way the system can ever recover from that. > > > > > > Thus, I'd really like to kill this. Does anybody care about it, and > > > can give me a strong enough reason to keep this anyway? > > > > The libvirt virDomainShutdown|Reboot APIs for triggering controlled > > shutdown/reboots of guest OS have support for using /dev/initctl with > > containers, as it was the lowest common denominator that easily worked > > across systemd, sysvinit & upstart. > > Ah, I see... But I wasn't aware Upstart even implemented that...
Maybe it wasn't actually upstart, but one of the other init systems. I just recall getting a patch from Debian folks to support it via the /run/initctl path, rather than /dev, and assumed that was upstart related. > > We could add further code to use a systemd specific interface if > > needed, so it wouldn't be the end of the world of /dev/initctl was > > removed, but it'd be nice to not have todo that. > > A simple fall back could be to send SIGRTMIN+4 to PID 1, if > /dev/initctl is not around. Yep, though we'd have to actually check that PID 1 is systemd, since if you run a container with a non-init program as PID 1, we don't want to be sending it SIGRTMIN+4 :-) > One more addendum to the original mail: > > We already declared the interface "obsolete" in the docs, which makes > me particularly keen on dropping it... I guess one thing is that even if support for /dev/intctl in systemd, it is an optional unit file, so libvirt probably needs to deal with the SIGRTMIN+4 stuff anyway, for case where the person building the container has that unit file disabled. So from that POV, deleting it won't make current situation that much worse. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
