[systemd-devel] What exactly is multi-seat? -- questions about logind

[Kian Kasad]

On 21/01/26 11:45AM, Lennart Poettering wrote:
> On Di, 26.01.21 01:43, Kian Kasad (kian at kasad.com) wrote:
> 
> > Hi all,
> >
> > After reading the documentation on logind and multi-seat (specifically
> > sd-login(3) and "Multi-Seat on Linux"), I still have some questions.
> >
> > First of all, what exactly is multi-seat? Does it just mean allowing
> > multiple sessions to be running at once, like for multiple users to be
> > logged into the same desktop, even though only one will be in use at a
> > time?
> 
> No, it means you can have multiple physical seats on the same
> computer. i.e. one computer with two displays, two keyboards, two
> mice, and that two people can work on it, independently of each other.

Ok, that makes sense. That's where I got confused; after reading the
definition of a "seat" in sd-login(3), I didn't get why a daemon would
be required if each program is using either all or none of the hardware
at one time.

Now I see that logind assigns some (or all) hardware to a specific
"seat" which a program can then run on, utilizing all the hardware in
the seat, even though that isn't necessarily all the hardware on the
system.

> > Second, why is logind needed for this? Is it not possible to do without
> > logind? I've run Xorg perfectly fine on systems without logind/systemd,
> > so is logind only needed for multiple sessions at once? Is it just to
> > handle the graphical device(s)?
> >
> > Third, is multi-seat possible at all without logind?
> >
> > Most of these questions arose because my main OS, Artix Linux, requires
> > logind (in the form of elogind) for Xorg, but I know that Xorg runs just
> > fine on Alpine Linux, which does not use logind at all.
> 
> I have no idea of those distro. I could not possible answer what they
> support and what not.
> 
> Like any software problem, you can always hack up your alternative
> solution. Software is generally reimplementable. If they reimplemented
> it, good for them. They can also fork our stuff, or just use our
> stuff, it's Free Software after all.
> 
> Either way, please contact the maintainers of your distro and
> "elogind" for help in general, this is the wrong forum for such
> questions.

I wasn't necessarily asking for help with those distros or elogind. I
was just using those as an example of systems running both with and
without systemd's logind. Sorry for the confusion.

--
Kian Kasad
PGP 0x1715EEAA14DAEC14
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