On Mon, Nov 25, 2024 at 12:57 PM Lennart Poettering <lenn...@poettering.net> wrote:
> On So, 24.11.24 12:35, Michael Kilburn (crusader.m...@gmail.com) wrote: > > > Hi, > > > > OS: Pop!_OS 22.04 LTS (Debian-based distro). User service (fluidsynth) > > fails to start on user login: > > > > ALSA lib seq_hw.c:466:(snd_seq_hw_open) open /dev/snd/seq failed: > > Permission denied > > > > because at that moment that device's ACL was not updated yet (to grant > > access to the user being logged in). > > > > When an active user logs in udev executes rules stored in > > /lib/udev/rules.d/70-uaccess.rules (via 73-seat-late.rules) to grant that > > user access to local devices (like soundcard, etc). > > > > Is there a way to express this dependency between user service and > > completion of execution of udev rules? > > > > Or (if this is a wrong approach) -- what is the correct way to deal with > > this? > > "uaccess" ḿeans access to devices can come and go any time, as the > user switches sessions, as sessions come and go. This means programs > which want access to such devices need to be written with this in > mind: watch udev events, and try to reopen the devices whenever you > receive an event for the relevant audio device and access is > permitted. (logind will re-retrigger relevant devices whenever the fg > session changes, so that the udev rules are rerun and apps are > notified about the new situation via udev events) > I don't see logind doing that here. It seems to only set the new ACLs directly (devnode_acl_all() in seat.c) but there are no uevents that I could see during a VT switch. -- Mantas Mikulėnas