Good day, we have been using LTTng successfully to capture snapshots on user defined tracepoints and it did provide invaluable to debug our issues. Thanks to all the contributors of this project!
We'd like to know if it would be possible to trigger on a kernel panic? I might be dubiously possible as you would still need to have the file-system working to write the results but I should ask. Looking at available kernel syscall, the "reboot" one seems like a good candidate, however I was not able to capture a snapshot on it. I have tested the setup below with "--name=chdir" syscall and it works, "cd" to a directory will create a trace. But no dice with reboot. Would you have any suggestions? Thanks for your help, Cheers Damien ============================ # Prep output dir mkdir /application/trace/ rm -rf /application/trace/* # Create session sudo lttng destroy snapshot-trace-session sudo lttng create snapshot-trace-session --snapshot --output="/application/trace/" sudo lttng enable-channel --kernel --num-subbuf=8 channelk sudo lttng enable-channel --userspace --num-subbuf=8 channelu # Configure session sudo lttng enable-event --kernel --syscall --all --channel channelk sudo lttng enable-event --kernel --tracepoint "sched*" --channel channelk sudo lttng enable-event --userspace --all --channel channelu sudo lttng add-context -u -t vtid -t procname sudo lttng remove-trigger trig_reboot sudo lttng add-trigger --name=trig_reboot \ --condition=event-rule-matches --type=kernel:syscall:entry \ --name=reboot\ --action=snapshot-session snapshot-trace-session \ --rate-policy=once-after:1 # start & list info sudo lttng start sudo lttng list snapshot-trace-session sudo lttng list-triggers #======== test it... sudo reboot #======= reconnect and Nothing :( $ ls -alu /application/trace/ drwxr-xr-x 2 u u 4096 May 15 2024 . drwxr-xr-x 10 u u 4096 May 15 2024 ..
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