<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div><span id="zwchr" data-marker="__DIVIDER__">----- On Apr 15, 2019, at 7:07 AM, Nicholas Sadjoli <nick.sadjoli@gmail.com> wrote:<br></span></div><div data-marker="__QUOTED_TEXT__"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">Dear Lttng dev Team,<br><div>I am currently interested in using lttng to measure the interrupt or hardware real-time latencies experienced within my user-space applications. Unfortunately I have been having issues installing lttng on my Raspberry Pi that is using the PREEMPT_RT patched kernel, version <span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px">4.14.91-rt49-v7+. The problems so far can be seen documented in the RPi Linux github forum page here: </span><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><a href="https://github.com/raspberrypi/linux/issues/2930" target="_blank">https://github.com/raspberrypi/linux/issues/2930</a></span></font><br data-mce-bogus="1"></div><div><span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px"><br></span></div><div><span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px">Initially I was about to just install the Debian package of the lttng onto the RPi, and just proceeded with the commands '</span><font face="Andale Mono WT, Andale Mono, Bitstream Vera Sans Mono, Liberation Mono, Nimbus Mono L, Ubuntu Mono, Monaco, Consolas, Lucida Console, Lucida Sans Typewriter, Courier New, Courier, monospace" color="rgba(0, 0, 0, 0.749019607843137)">sudo apt-get install lttng-modules-dkms liblttng-ust-dev lttng-tools' </font>However, I was unable to use lttng package at all and found out that for the RPi, a build from source is necessary for lttng, as described here: <span style="background-color:transparent"><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><a href="https://stackoverflow.com/questions/52386448/linux-trace-tool-lttng-on-raspbian-kernel-tracer-not-available" target="_blank">https://stackoverflow.com/questions/52386448/linux-trace-tool-lttng-on-raspbian-kernel-tracer-not-available</a></span></font></span><br data-mce-bogus="1"></div><div><span style="background-color:transparent"><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></span></div><div><span style="background-color:transparent"><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">Following their suggestion, I then tried to build the lttng packages from source, and even re-building the RPi kernel locally to ensure the kernel headers are in the RPi and linked up properly to the source packages. </span></font></span></div><div><span style="background-color:transparent"><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></span></div><div><span style="background-color:transparent"><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">Unfortunately when I tried to do this for the lttng-modules package, it instead gave me the following warning in my latest attempt: </span></font></span></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">I</span></font><span style="font-size:14px;color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol"">n file included from /home/pi/BangEco_rvmscan/stagelight_project/lttng/lttng-modules/probes/lttng-kprobes.c:31:0:</span></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">/home/pi/BangEco_rvmscan/stagelight_project/lttng/lttng-modules/probes/../blacklist/kprobes.h:19:4: error: #error "Your kernel is known to have buggy optimized kprobes implementation. Fixed by commit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c \"ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction\" in Linux. Disable CONFIG_OPTPROBES or upgrade your kernel."</span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"> # error "Your kernel is known to have buggy optimized kprobes implementation. Fixed by commit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c \"ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction\" in Linux. Disable CONFIG_OPTPROBES or upgrade your kernel."</span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">I then tried to turn off the CONFIG_OPTPROBES kernel config, but it seemed to be automatically overwritten during kernel building and is considered an important part of the real-time RPi kernels. Has such problems been reported with this version of the PREEMPT_RT kernel in the past (again, the current kernel version that I am using is </span></font><span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px">4.14.91-rt49-v7+)? If there are I would like to know how this issue was resolved so that I can properly build and use the lttng package for my project.</span></div></div></div></div></div></blockquote><div>Hi Nicholas,<br></div><div><br data-mce-bogus="1"></div><div>It looks like our lttng-modules kernel version blacklist is acting exactly as it should. Looking at this<br data-mce-bogus="1"></div><div>git tree:<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>git clone https://github.com/raspberrypi/linux.git -b rpi-4.14.y-rt<br data-mce-bogus="1"></div><div><pre><code class="language-sh hljs bash"></code></pre></div><div>I notice that in the git log, we find this bogus commit:<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>commit f9e0bc710347fadad55910846ee36f0681d0dca8<br>Author: Kees Cook <keescook@chromium.org><br>Date: Tue Oct 30 22:12:56 2018 +0100<br><br> ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE<br> <br> commit e46daee53bb50bde38805f1823a182979724c229 upstream.<br><br data-mce-bogus="1"></div><div>But not the fix for it (upstream):<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>commit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c<br>Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com><br>Date: Tue Feb 5 16:37:40 2019 +0100<br><br> ARM: 8834/1: Fix: kprobes: optimized kprobes illegal instruction<br><br data-mce-bogus="1"></div><div>So lttng-modules refuses to build against your kernel configuration with CONFIG_OPTPROBES=y</div><div>to save you the trouble of having kprobes trigger illegal instruction OOPS at runtime.<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>I'm unusure who maintains that raspberrypi rt kernel tree. However, the upstream rt tree<br data-mce-bogus="1"></div><div>for 4.14-rt maintained by Tom Zanussi seems to contain the fix:<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div><a href="https://kernel.googlesource.com/pub/scm/linux/kernel/git/rt/linux-stable-rt/+/refs/heads/v4.14-rt">https://kernel.googlesource.com/pub/scm/linux/kernel/git/rt/linux-stable-rt/+/refs/heads/v4.14-rt</a><br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>(currently at 4.14.109-rt57).<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>So you should contact your raspberrypi linux rt tree clone maintainer and ask him<br data-mce-bogus="1"></div><div>to upgrade, or, as stated in the #error generated by lttng-modules, simply ensure<br data-mce-bogus="1"></div><div>CONFIG_OPTPROBES is unset when you build your kernel. You should ask the<br data-mce-bogus="1"></div><div>raspberrypi community advice on how to ensure this configuration option is not</div><div>overridden by the raspberrypi build system.<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>Thanks,<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>Mathieu</div><div><br data-mce-bogus="1"></div><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div><span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px"><br></span></div><div><span style="color:rgb(36,41,46);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji","Segoe UI Symbol";font-size:14px"><br></span></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">Thank you so much for your attention and looking forward to your reply soon.</span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">Best Regards,</span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px"><br></span></font></div><div><font face="-apple-system, BlinkMacSystemFont, Segoe UI, Helvetica, Arial, sans-serif, Apple Color Emoji, Segoe UI Emoji, Segoe UI Symbol" color="#24292e"><span style="font-size:14px">Nicholas Sadjoli</span></font></div></div></div></div></div>
<br>_______________________________________________<br>lttng-dev mailing list<br>lttng-dev@lists.lttng.org<br>https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev<br></blockquote></div><div><br></div><div data-marker="__SIG_POST__">-- <br></div><div>Mathieu Desnoyers<br>EfficiOS Inc.<br>http://www.efficios.com</div></div></body></html>