[systemd-devel] logind: multiseat without framebuffer graphic cards

[Kay Sievers]

On Sun, Nov 25, 2012 at 6:35 PM, Oleg Samarin <osamarin68 at gmail.com> wrote:
> В Вс., 25/11/2012 в 02:21 +0100, Kay Sievers пишет:
>> On Sat, Nov 24, 2012 at 10:46 PM, Lennart Poettering
>> <lennart at poettering.net> wrote:
>>
>> > This sounds as if it should be tagged with uaccess, so that it is
>> > managed by dynamic ACLs as sessoins become active and inactive.
>> >
>> > Kay, what's the story behind /dev/snd/seq and ACLs?
>>
>> Should work fine when the driver is loaded. The module is usually not
>> loaded though.
>
> If snd_seq is not loaded, then /dev/snd/seq has no ACL at all.

Right. As mentioned, it is a known limitation.

> After loading snd_seq /dev/snd/seq becomes accessible in a single seat
> enviroment. But after configuring seat1 it stops working on both seat0
> and seat1.

Sure, only one seat has access to one and the same device at a time.

>> The auto-loading on user access by the kernel does not trigger,
>> because the ACL only gets applied to a real device, not a "dead"
>> device node.
>>
>> So, either the primary permissions of the node need to be relaxed, the
>> module needs to be always force-loaded, or the ACL setting logic would
>> need to be changed to include "dead" nodes without a device.
>
> F17 has a bug causes snd_seq is not loaded on boot. But after I used a
> workaround (placing 'install snd-pcm /usr/sbin/modprobe --ignore-install
> snd-pcm && /usr/sbin/modprobe snd-seq'
> to /etc/modprobe.d/dist-alsa.conf), /dev/snd/seq started working

A single entry in /etc/modules-load.d/ (man modules-load.d) sounds
like the better option.

> but  only in single-seat environment.

Right, there is currently not support at all for sharing devices
across multiple users.

Kay