[Dev] Tizen 3 services: use case for multi user

Kaskinen, Tanu tanu.kaskinen at intel.com
Wed Sep 10 09:09:31 GMT 2014


On Tue, 2014-09-09 at 18:53 +0200, Dominig ar Foll (Intel OTC) wrote:
> Hello;
> 
> Manuel Bachman has added a page on Multi-user Display Management
> see
> https://wiki.tizen.org/wiki/Multi-user_Architecture#Multi_User_use_cases
> 
> Your comments are welcome.

Thanks for the wiki page!

On the multi-user display management page[1] there is this statement:

    User sessions are not associated with a particular seat ; nor
    are applications.

I feel that some clarifications are needed for that statement. logind
associates each session with zero or one seat, and last time I checked
this on Common, all sessions are currently assigned to seat0 by default.
Does the statement mean that logind can assign whatever it wants, but we
ignore that? Or do you think that things should be changed so that
logind doesn't assign sessions to any seat? Or does the statement only
mean that sessions are not associated *permanently* with a particular
seat? (I hope it's the last one, but in the rest of this mail, I'll
assume that it's not that.)

What's the rationale behind not associating sessions with seats? I know
we need to support moving running applications between seats, are there
other reasons? Do you perhaps want to allow one session to span multiple
seats simultaneously?

If the motivation is just to be able to move applications between seats,
what do you think of the approach that Jussi has proposed: don't move
single applications, but move entire sessions between seats? This means
that sessions are associated with a seat, but that association can
change dynamically.

As a PulseAudio developer, I'm interested in this, because currently
PulseAudio relies on logind's device ACL management to figure out which
sound cards are assigned to the user, and logind's device ACL management
in turn relies on sessions being correctly associated with seats. If we
want to support per-seat sound cards, the existing solution in
PulseAudio should work quite well for that (when the user's session
moves from one seat to another, the set of sound cards assigned to the
user changes automatically). If the sessions aren't correctly associated
with seats at logind level, we'd need some other solution in PulseAudio
to support per-seat sound cards, and currently I don't understand why we
should take that route.

[1] https://wiki.tizen.org/wiki/Multi-user_DisplayManagement

-- 
Tanu


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