Bug #1184

can't report find any system calls with lttng list --kernel --syscall

Added by Colin King almost 2 years ago. Updated almost 2 years ago.

Target version:
Start date:
Due date:
% Done:


Estimated time:


Steps to reproduce:

sudo lttng create test
sudo lttng list --kernel --syscall


System calls:

.. and no system calls reported(!?). Tested against Ubuntu Bionic with mainline kernels from 5.1 down to 4.8 on amd64 and i386 from;O=D - interestingly pre-4.8 kernels this works fine. Was unsuccessful in bisecting this because 4.7-rcX kernels break in the lttng module build.

Using lttng-modules-dkms 2.10.5-1ubuntu1.2


config-4.15.0-50-generic (214 KB) config-4.15.0-50-generic Colin King, 05/22/2019 12:38 PM
0001-Fix-initialize-syscall-table-when-kernel-tracer-is-l.patch (1.54 KB) 0001-Fix-initialize-syscall-table-when-kernel-tracer-is-l.patch Fix: initialize syscall table when kernel tracer is lazily initialized Mathieu Desnoyers, 05/23/2019 12:09 PM

Updated by Mathieu Desnoyers almost 2 years ago

What is the version of your lttng-tools ?

You can check with lttng-sessiond --version




Updated by Colin King almost 2 years ago

$ lttng-sessiond --version

dpkg -l | grep lttng
ii liblttng-ctl0:amd64 2.10.2-1 amd64 LTTng control and utility library
ii liblttng-ust-ctl4:amd64 2.10.1-1 amd64 LTTng 2.0 Userspace Tracer (trace control library)
ii lttng-modules-dkms 2.10.5-1ubuntu1.2 all Linux Trace Toolkit (LTTng) kernel modules (DKMS)
ii lttng-tools 2.10.2-1 amd64 LTTng control and utility programs


Updated by Mathieu Desnoyers almost 2 years ago

Can you provide an example kernel config for the 5.1 kernel which triggers the issue ?


Updated by Mathieu Desnoyers almost 2 years ago

It appears to work fine here on a Ubuntu Bionic running the following kernel:

5.0.0-15-generic #16~18.04.1-Ubuntu SMP Tue May 7 14:17:37 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Package: linux-image-5.0.0-15-generic
Architecture: amd64
Version: 5.0.0-15.16~18.04.1+signed1
Built-Using: linux (= 5.0.0-15.16~18.04.1)
Filename: pool/main/l/linux-signed-hwe-edge/linux-image-5.0.0-15-generic_5.0.0-15.16~18.04.1+signed1_amd64.deb

This seems to point towards an issue with the kernel configuration you are using on the ppa.


Updated by Colin King almost 2 years ago

Oops, I fat fingered the data in #3, just to be clear, this only fails on 32 bit x86 arches, e.g.

Ubuntu bionic, uname -a
Linux bionic-i386 4.15.0-50-generic #54-Ubuntu SMP Mon May 6 18:45:45 UTC 2019 i686 i686 i686 GNU/Linux I guess the config is not correct on these. Just so I can sanity check things, what specific config is required?


Updated by Colin King almost 2 years ago

config of 4.15 32 bit x86 that does not work.

Also available in: Atom PDF