I get the intuition behind the suggestion to aggregate using logind seats, as
far as it goes. But it still seems to me that this just pushes the question
back: how do you identify which card is which in order to assign it to a seat?
Normally this is done using udev rules, right? Additionally, I'm working with
some constraints that not all of the compositors are logind-aware. I realize
that's not really your problem, and it doesn't really influence the merits of
your suggestion.
The /dev/dri/by-path idea works, I suppose, if you have different physical
graphics cards. In my case, that's not true. These are virtualized cards that
the silicon vendor's DRM drivers use to expose different subsets of DRM
resources as different cards. So there's only one /dev/dri/by-path card here.
Think: DRM leases, but with the lessees popping out as card nodes rather than
arranged dynamically using the drm ioctl()'s to manufature leases.
The use-case here is to allow separate DRM domains for each of several
containers. It's not really desirable to try to funnel everybody's graphics
through a common compositor that runs all the connectors.
Thanks for the thoughts.
-Matt
On 9/22/21, 10:29 AM, "Simon Ser" <cont...@emersion.fr> wrote:
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Maybe try creating multiple physical seats with logind, and start each
compositor on its own seat? A physical seat is a collection of devices like
DRM nodes and evdev device files.
Also udev creates files in /dev/dri/by-path/, these should be stable across
reboots. `udevadm settle` before a compositor start-up can wait for udev to
finish its job.
Out of curiosity, can you explain your use-case? Why do you need to start
multiple compositors, each on its own GPU?
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