From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicholas Sadjoli Subject: Problems setting up lttng on PREEMPT_RT Raspberry Pi Date: Mon, 15 Apr 2019 19:07:43 +0800 Message-ID: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5586000169427430650==" Return-path: Received: from mail-it1-x135.google.com (mail-it1-x135.google.com [IPv6:2607:f8b0:4864:20::135]) by lists.lttng.org (Postfix) with ESMTPS id 44jQhW6jTkz1Jp2 for ; Mon, 15 Apr 2019 07:07:55 -0400 (EDT) Received: by mail-it1-x135.google.com with SMTP id w15so25934574itc.0 for ; Mon, 15 Apr 2019 04:07:55 -0700 (PDT) List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" To: lttng-dev@lists.lttng.org List-Id: lttng-dev@lists.lttng.org --===============5586000169427430650== Content-Type: multipart/alternative; boundary="00000000000005de8705868faafa" --00000000000005de8705868faafa Content-Type: text/plain; charset="UTF-8" Dear Lttng dev Team, 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 4.14.91-rt49-v7+. The problems so far can be seen documented in the RPi Linux github forum page here: https://github.com/raspberrypi/linux/issues/2930 Initially I was about to just install the Debian package of the lttng onto the RPi, and just proceeded with the commands 'sudo apt-get install lttng-modules-dkms liblttng-ust-dev lttng-tools' 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: https://stackoverflow.com/questions/52386448/linux-trace-tool-lttng-on-raspbian-kernel-tracer-not-available 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. Unfortunately when I tried to do this for the lttng-modules package, it instead gave me the following warning in my latest attempt: In file included from /home/pi/BangEco_rvmscan/stagelight_project/lttng/lttng-modules/probes/lttng-kprobes.c:31:0: /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." # 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." 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 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. Thank you so much for your attention and looking forward to your reply soon. Best Regards, Nicholas Sadjoli --00000000000005de8705868faafa Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Dear Lt= tng dev Team,

I am currently interested in using lttng t= o measure the interrupt or hardware real-time latencies experienced within = my user-space applications. Unfortunately I have been having issues install= ing lttng on my Raspberry Pi that is using the PREEMPT_RT patched kernel, v= ersion=C2=A04.14.91-rt49-v7+. The problems so far can be seen documente= d in the RPi Linux github forum page here:=C2=A0https://github.com/raspberrypi/linux/issues/2930

Initially I was about to just install= the Debian package of the lttng onto the RPi, and just proceeded with the = commands 'sudo apt-get install lttng-mod= ules-dkms liblttng-ust-dev lttng-tools' However, I was unable to= use lttng package at all and found out that for the RPi, a build from sour= ce is necessary for lttng, as described here:=C2=A0https://stackoverflow.com/questions/52386448= /linux-trace-tool-lttng-on-raspbian-kernel-tracer-not-available=C2=A0
=
Following their suggestion, I then tried to build the lttng pac= kages from source, and even re-building the RPi kernel locally to ensure th= e kernel headers are in the RPi and linked up properly to the source packag= es.=C2=A0

Unfortunately when I tried to do this for the lttng-m= odules package, it instead gave me the following warning in my latest attem= pt:=C2=A0

= In file included from /home/pi/BangEco_rvmscan/stagelight= _project/lttng/lttng-modules/probes/lttng-kprobes.c:31:0:
= /home/pi/BangEco_rvmscan/stagelight= _project/lttng/lttng-modules/probes/../blacklist/kprobes.h:19:4: error: #er= ror "Your kernel is known to have buggy optimized kprobes implementati= on. Fixed by commit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c \"ARM: 88= 34/1: Fix: kprobes: optimized kprobes illegal instruction\" in Linux. = Disable CONFIG_OPTPROBES or upgrade your kernel."
<= div>=C2=A0#=C2=A0 error "Your = kernel is known to have buggy optimized kprobes implementation. Fixed by co= mmit 0ac569bf6a7983c0c5747d6df8db9dc05bc92b6c \"ARM: 8834/1: Fix: kpro= bes: optimized kprobes illegal instruction\" in Linux. Disable CONFIG_= OPTPROBES or upgrade your kernel."

I then tried to turn off the CONFIG_OPTPROBES kernel= config, but it seemed to be automatically overwritten during kernel buildi= ng and is considered an important part of the real-time RPi kernels. Has su= ch problems been reported with this version of the PREEMPT_RT kernel in the= past (again, the current kernel version that I am using is=C2=A04.14.91-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.


<= div>Thank you so much for your atte= ntion and looking forward to your reply soon.



Best Regards,



Nicholas Sadjoli
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