From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Bultel Date: Thu, 26 Jun 2014 16:06:32 +0200 Subject: [Buildroot] Fwd: Re: [lttng-dev] "lttng enable-event" fails In-Reply-To: <53AC1E14.4030700@wanadoo.fr> References: <53AC1E14.4030700@wanadoo.fr> Message-ID: <53AC28E8.7080800@wanadoo.fr> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hi, I have submitted the bug to the lttng mailing list, too. The coredump is not usable. Below, new information: it works with the old 2012.10 compiler from Linaro. To do the test, I had to hack into toolchain-external to re-enable support of it. regards, Thierry -------- Message original -------- Sujet: Re: [lttng-dev] "lttng enable-event" fails Date : Thu, 26 Jun 2014 15:20:20 +0200 De : Thierry Bultel Pour : David Goulet Copie ? : lttng-dev at lists.lttng.org Some other useful information probably: The bug does not happen with the (old) Linaro 2012.10 compiler: # ./host/usr/bin/arm-linux-gnueabihf-gcc --version arm-linux-gnueabihf-gcc (crosstool-NG linaro-1.13.1-4.7-2012.10-20121022 - Linaro GCC 2012.10) 4.7.3 20121001 (prerelease) Copyright ? 2012 Free Software Foundation, Inc. Whereas it happens with the one provided by buildroot: ../buildroot_agv_v15_amos820/host/usr/bin/arm-linux-gcc --version arm-linux-gcc (Buildroot 2014.02-rc3-00323-g2f12017) 4.7.3 Copyright ? 2012 Free Software Foundation, Inc. Thus I am submitting that bug report to buildroot as well. Regards Thierry Le 24/06/2014 15:53, David Goulet a ?crit : > On 24 Jun (08:47:21), Thierry Bultel wrote: >> Hi, >> >> I am using lttng (2.4.1), target is ARM Cortex A9; compiler is gcc-4.7.3, >> but I have the same issue with gcc-4.8.2 >> The kernel is Freescale's 3.0.35-4.1.0 >> >> >> lttng fails to start: >> >> [root at buildroot ~]# lttng create >> Session auto-19700319-135920 created. >> Traces will be written in /root/lttng-traces/auto-19700319-135920 >> [root at buildroot~]# lttng enable-event --kernel --all >> PERROR [5831/5915]: wait: Success (in run_as_clone() at runas.c:243) >> Error: Trace directory creation error >> Error: Events: Kernel create session failed (channel channel0, session >> auto-19700319-135920) >> >> My analysis show that lttng attempts to create the trace directory, when >> "lttng enable-event" is called. >> To do so, it uses a slave thread that performs a kind of "mkdir -p" , >> that thread is spawned via a call to "clone" >> and the father waits for it via "waitpid". >> >> When the slave returns, waitpid says it is not completed. Added a little >> code to shows that the thread >> is killed with SIGSEGV at the time it calls "return" >> >> Changing it to call "exit" instead, makes it a little better, but other >> numerous errors come when >> calling "lttng start" >> >> Did anyone encounter such an issue ? > > Hrm, tbh I never tried lttng-tools on ARM but if a SIGSEGV is raised you > should be able to get a core dump and with gdb we can understand which > callsite failed badly. > > Thanks! > David > >> >> Best regards >> Thierry Bultel >> >> >> >> >> _______________________________________________ >> lttng-dev mailing list >> lttng-dev at lists.lttng.org >> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev