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Multiseat

Multiseat

Posted Jan 28, 2013 14:06 UTC (Mon) by Yenya (subscriber, #52846)
Parent article: Poettering: The Biggest Myths

Disclaimer: I am a long-term multiseat Linux user - my home workstation has been dual-seat for 10+ years.

For me, there are two stumbling blocks for a multiseat workstation in current Linux distros (e.g. Fedora 17): pulseaudio and gdm/systemd.

For pulseaudio, the situation is actually not so bad: PA has been originally designed as a flexible multi-purpose tool. It is possible to run PA in system mode, and use a single system-wide daemon to split a 6-channel on-board sound card to three independent dual-channel outputs. The problem is that system-wide mode is not supported (even discouraged in the PA documentation[1]), and for example Fedora does not even contain the init-script (or .service file) for system-wide PA, and it also does not contain suitable SELinux policy module for it.

The other problem is this shiny new systemd/gdm "autoconfiguration". It would be nice for those rare cases, where everything works as authors intended. My problem is that the Xorg.conf file is used only for the primary seat, and for other seats, a temporary minimal file is generated under /run, with no control over its contents and no control over Xorg(1) command-line arguments. For example, my ~3 years old home workstation with two Radeon HD 3450 boards needs the -isolateDevice command-line argument, and there is no way to set it with systemd/gdm. I have been using manual setup and xdm for the last several years, which works without problems.

So from my point of view, systemd definitely does not enable the multiseat capability. This capability has been there for at least ten years, and works without (if not despite) systemd.

FWIW, there is 5+ years old Fedora Bugzilla entry about gdm not being able to pass the arbitrary Xorg command-line options:
https://bugzilla.redhat.com/show_bug.cgi?id=451562

[1] http://www.freedesktop.org/wiki/Software/PulseAudio/Docum...


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Multiseat

Posted Jan 28, 2013 14:24 UTC (Mon) by cortana (subscriber, #24596) [Link]

It's a sad bug, but I'm surprised no one in 5 years cooked up a simple patch for gdm-simple-slave to make it pull config options from a file in /etc.

Multiseat

Posted Jan 28, 2013 14:27 UTC (Mon) by ovitters (subscriber, #27950) [Link]

There is a patch, it was rejected as they wanted to wait on multiseat. There now is multiseat, but bug is still lost in the bugtracker. See my other reply on the recent thing on systemd-devel.

Multiseat

Posted Jan 28, 2013 14:26 UTC (Mon) by ovitters (subscriber, #27950) [Link]

For PA system-wide, suggest filing a bug. That something is not supported does not mean you cannot have an init script for it. Maybe it was done to discourage or to make clear that it is not the supported mode, no idea.

For multiseat, only this week there was a thread on systemd-devel that multiseat sometimes needs more configuration. I have 0 clue on multiseat, and don't understand what kind of configuration was needed, nor what you're doing with multiseat. Maybe they are targetting what you need, maybe not. Suggest writing to systemd-devel.

Multiseat

Posted Jan 28, 2013 15:27 UTC (Mon) by Yenya (subscriber, #52846) [Link]

As for the system-wide PA: read the bottom of the page mentioned in my previous post:

> But my distro is shipping an init script for PA!
>
> Ignore that. It's stupid. They shouldn't be doing this.

Given Lennart Poettering's involvement in Fedora, I don't expect Fedora to go directly against his suggestions in this case. But yes, I may give it a try nevertheless.


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