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 écrit :
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@buildroot ~]# lttng create
Session auto-19700319-135920 created.
Traces will be written in /root/lttng-traces/auto-19700319-135920
[root@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
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