[systemd-devel] systemd-udevd rule tracing ?

[Branko]

HI,

I have a problem with and FTDI-based device. It keeps dissapearing and 
reappearing on every 1-2s or so. Nothing in dmesg to indicate failure.

I'm trying to make my way through systemd-udevd, but it's not easy to 
debug things there ( neither is classic udev BTW).

udevadm monitor -u shows that whole interface is being released, 
unbound,rremoved and then added again.
Interestingly, it behaves the same with --kernel as with --udev options.
So it seems that flurry of re/mount requests are coming from kernel 
(5.4.43), not from something in rules setup - or so it seems now.


NO good, obvious reason why. Kernel shows no error, system-udevd log 
show nothing.

It just repeats that add/remove cycle.

Daemon has -D option, which changes nothing for me - I still get the 
same info back.

Is there a way to trace down which rule gets executed and why ?

udevadm test /dev/ttyUSB0 gets me nothing of use - just a list of rule 
files that were parsed, not what was actually executed.

BTW, while slightly offtopic, is there somethign in kernel that would 
get me more debug info ?

There used to be some "generate debug info" in USB stack some time ago...