From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel.Thibault@drdc-rddc.gc.ca (Thibault, Daniel) Date: Mon, 25 Nov 2013 19:22:44 +0000 Subject: [lttng-dev] make a trace_event in a module (driver) Message-ID: <48CF5AC71E61DB46B70D0F388054EFFD267A5E6B@VAL-E-01.valcartier.drdc-rddc.gc.ca> > Date: Mon, 25 Nov 2013 12:00:14 -0500 > From: J?r?mie Galarneau >> Aha! There is one crucial mistake in the ibm.com document: he installs the packages in the wrong order. lttng-tools must be installed AFTER lttng-modules and lttng-ust. lttng-modules can be installed before, during or after lttng-ust, but userspace-rcu must be installed before lttng-ust. >> The problem is that the configure of lttng-tools detects the presence or absence of lttng-modules and also detects the presence or absence of lttng-ust, and adjusts to both. By installing lttng-tools before lttng-modules, you've built an lttng-tools set that CANNOT be used to trace the kernel. >> >> So, try again from scratch, making sure to install lttng-tools last. > > lttng-tools checks for kernel modules at run time, not at configure time. You can safely install lttng-modules after lttng-tools and still use kernel tracing. > > Regards, > J?r?mie Dang, you're right. The build of lttng-tools reacts to the presence or absence of lttng-ust, but is indifferent to the presence or absence of lttng-modules. (Only liblttng-ctl.a is different, probably some internal timestamps or some such) > klaus at ubuntu:~$ sudo lttng -vvv start > DEBUG2 [2854/2854]: Config file path found: /home/klaus (in get_session_name() at utils.c:57) > DEBUG1 [2854/2854]: Session name found: auto-20131124-091639 (in get_session_name() at utils.c:58) > DEBUG1 [2854/2854]: Starting tracing for session auto-20131124-091639 (in start_tracing() at commands/start.c:81) > DEBUG1 [2854/2854]: LSM cmd type : 16 (in send_session_msg() at lttng-ctl.c:131) > 'ctrl c' > klaus at ubuntu:~$ Let's try to identify the module responsible. First, make sure lttng-sessiond is NOT running. Then, do this in one shell: $ sudo -H lttng-sessiond -vvv It should fail after loading one of the modules. You can also try: $ sudo -H lttng-sessiond -vvv --no-kernel In which case you should be able to do any lttng command except those involving the kernel. For example, 'lttng list -u'. Daniel U. Thibault Protection des syst?mes et contremesures (PSC) | Systems Protection & Countermeasures (SPC) Cyber s?curit? pour les missions essentielles (CME) | Mission Critical Cyber Security (MCCS) R & D pour la d?fense Canada - Valcartier (RDDC Valcartier) | Defence R&D Canada - Valcartier (DRDC Valcartier) 2459 route de la Bravoure Qu?bec QC G3J 1X5 CANADA Vox : (418) 844-4000 x4245 Fax : (418) 844-4538 NAC : 918V QSDJ Gouvernement du Canada | Government of Canada