I have a Linux system based on minimal Ubuntu 22.04 and kernel 6.5.3 that uses systemd as its init.
Shortly after boot, something causes the system to suspend, which is undesirable, as there’s no means to wake it.
I suspect it’s something to do with a USB-attached touch pad, because swapping for a different model of touch-pad fixes the symptom. Note that swapping for another of the same model still suspends, so it’s not a failed peripheral; also the problem touch pad works find with a different model of motherboard, so it’s clearly due to the combination of host and device. Also, this behaviour didn’t occur with a previous installation based on Ubuntu 14.04 with Upstart as init.
I have been able to access the system and run systemctl mask target.sleep; that provides an adequate work-around for the time being. But I’d like to understand and perhaps eliminate the root cause. What tools are available to investigate why systemd is attempting to reach the “sleep” target?
I’m hoping there’s something I can inspect on the running system (with target.sleep masked) to track down where the desire to sleep originates. If needed, I can systemctl unmask target.sleep (causing the system to suspend immediately) then inspect logs after powering down and rebooting. I’m happy to install extra packages or to recompile the kernel with extra options – I just don’t know which ones I should be using.