Merge branch 'master' into add-gh-actions-readme

.config-fragment

@@ -1,6 +1,25 @@
 CONFIG_PREEMPT_RT=y
+CONFIG_LOCKUP_DETECTOR=n
+CONFIG_DETECT_HUNG_TASK=n
 CONFIG_NO_HZ_FULL=y
 CONFIG_HZ_1000=y
 # CONFIG_AUFS_FS is not set
-CONFIG_CPU_FREQ=n
+CONFIG_CPU_FREQ=y
+CONFIG_CPU_FREQ_GOV_PERFORMANCE=y
+CONFIG_CPU_FREQ_GOV_ONDEMAND=y
+CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y
 CONFIG_CPU_IDLE=n
+CONFIG_LTTNG=y
+# CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM is not set
+CONFIG_LTTNG_CLOCK_PLUGIN_TEST=y
+CONFIG_MODULES=y
+CONFIG_KALLSYMS=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_TRACEPOINTS=y
+# CONFIG_KPROBES is not set
+CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
+CONFIG_EVENT_TRACING=y
+CONFIG_PERF_EVENTS=y
+# CONFIG_KRETPROBES is not set
+# CONFIG_KALLSYMS_ALL is not set
+

.github/workflows/rpi4-kernel-build.yml

@@ -14,13 +14,17 @@ name: 'RPI4 RT Kernel build'
 
 # Controls when the workflow will run
 on:
-  # Triggers the workflow on push only if kernel configuration changed
+  # Trigger the workflow on push or pull request,
+  # but only for the master branch
   push:
-    paths:
-      - '.config-fragment'
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
 
   # Allows you to run this workflow manually from the Actions tab
-  # manual start works on teh default branch only
+  # manual start works on the default branch only
   workflow_dispatch:
 
 # A workflow run is made up of one or more jobs that can run sequentially or in parallel
@@ -160,4 +164,4 @@ jobs:
         with:
           name: 'RPI4 RT Kernel deb packages'
           path: ~/linux_build/*.deb
-
+

Dockerfile

@@ -4,17 +4,17 @@
 # if the build arguments defined it will build a corresponding version instead
 # $ docker build [--build-arg UNAME_R=<raspi release>] [--build-arg RT_PATCH=<RT patch>] -t rtwg-image .
 #
-# where <raspi release> is in a form of 5.4.0-1034-raspi, 
+# where <raspi release> is in a form of 5.4.0-1034-raspi,
 #     see https://packages.ubuntu.com/search?suite=default&section=all&arch=any&keywords=linux-image-5.4&searchon=names
-# and <RT patch> is in a form of 5.4.106-rt54, 
+# and <RT patch> is in a form of 5.4.106-rt54,
 #     see http://cdn.kernel.org/pub/linux/kernel/projects/rt/5.4/older
 #
-# $ docker run -it rtwg-image bash 
+# $ docker run -it rtwg-image bash
 #
 # and then inside the docker
 # $ $HOME/linux_build && cd `ls -d */`
 # $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j `nproc` deb-pkg
-# 
+#
 # user ~/linux_build/linux-raspi-5.4.0 $ ls -la ../*.deb
 # -rw-r--r-- 1 user user  11430676 May 17 14:40 ../linux-headers-5.4.101-rt53_5.4.101-rt53-1_arm64.deb
 # -rw-r--r-- 1 user user 487338132 May 17 14:40 ../linux-image-5.4.101-rt53-dbg_5.4.101-rt53-1_arm64.deb
@@ -32,13 +32,14 @@ ARG DEBIAN_FRONTEND=noninteractive
 # setup timezone
 RUN echo 'Etc/UTC' > /etc/timezone \
     && ln -s -f /usr/share/zoneinfo/Etc/UTC /etc/localtime \
-    && apt-get update && apt-get install -q -y tzdata apt-utils lsb-release software-properties-common \
+    && apt-get update && apt-get install -q -y tzdata apt-utils lsb-release software-properties-common openssh-client \
     && rm -rf /var/lib/apt/lists/*
 
 ARG ARCH=arm64
 ARG UNAME_R
 ARG RT_PATCH
 ARG triple=aarch64-linux-gnu
+ARG LTTNG=2.12
 
 # setup arch
 RUN apt-get update && apt-get install -q -y \
@@ -95,6 +96,10 @@ RUN sudo apt-get update \
     && apt-get source linux-image-`cat /uname_r` \
     && sudo rm -rf /var/lib/apt/lists/*
 
+# install lttng dependencies
+RUN sudo apt-get update \
+  && sudo apt-get install -y libuuid1 libpopt0 liburcu6 libxml2 numactl
+
 COPY ./getpatch.sh /getpatch.sh
 
 # get the nearest RT patch to the kernel SUBLEVEL
@@ -111,6 +116,20 @@ RUN cd `ls -d */` \
 RUN wget http://cdn.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patch-`cat $HOME/rt_patch`.patch.gz \
     && gunzip patch-`cat $HOME/rt_patch`.patch.gz
 
+# download lttng source for use later
+# TODO(flynneva): make script to auto-determine which version to get?
+RUN cd $HOME \
+  && sudo apt-add-repository ppa:lttng/stable-${LTTNG} \
+  && sudo apt-get update \
+  && apt-get source lttng-modules-dkms
+
+# run lttng built-in script to configure RT kernel
+RUN set -x \
+  && export KERNEL_DIR=`ls -d */` \
+  && cd $HOME \
+  && cd `ls -d lttng-*/` \
+  && ./scripts/built-in.sh ${HOME}/linux_build/${KERNEL_DIR}
+
 # patch `raspi` kernel, do not fail if some patches are skipped
 RUN cd `ls -d */` \
     && OUT="$(patch -p1 --forward < ../patch-`cat $HOME/rt_patch`.patch)" || echo "${OUT}" | grep "Skipping patch" -q || (echo "$OUT" && false);

README.md

@@ -92,12 +92,14 @@ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig
 Alternatively, you can modify ```.config-fragment``` and then merge your changes in the ```.config``` by running
 
 ```bash
+cd $HOME/linux_build/linux-raspi-*
 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- ./scripts/kconfig/merge_config.sh .config $HOME/linux_build/.config-fragment
 ```
 
 ### Kernel build
 
 ```bash
+cd $HOME/linux_build/linux-raspi-*
 make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -j `nproc` deb-pkg
 ```
 
@@ -172,6 +174,12 @@ Linux ubuntu 5.4.101-rt53 #1 SMP PREEMPT_RT Mon May 17 12:10:16 UTC 2021 aarch64
 
 To build ```x86_64``` Linux kernel, see [Building Realtime rt_preempt kernel for ROS 2](https://index.ros.org/doc/ros2/Tutorials/Building-Realtime-rt_preempt-kernel-for-ROS-2)
 
+## Why is LTTng included in the kernel?
+
+[LTTng](https://lttng.org/docs) stands for _Linux Trace Toolkit: next generation_ and is an open source toolkit that enables low-level kernel tracing which can be extremely useful when calculating callback times, memory usage and many other key characteristics.
+
+As this repository is within the `ros-realtime` organization it can be assumed that most users will install ROS 2 on the end system - which then they can use `ros2_tracing` to trace various things. Since [`ros2_tracing`](https://gitlab.com/ros-tracing/ros2_tracing) uses LTTng as its tracer, and since [the `lttng-modules` package is not easily available](https://github.com/ros-realtime/rt-kernel-docker-builder/issues/16) for the raspberry-pi RT linux kernel we build it into the kernel here as a work around.
+
 ## References
 
 * [ROS Real-Time Working group documentation](https://real-time-working-group.readthedocs.io/en/rolling/Guides/Real-Time-Operating-System-Setup/Real-Time-Linux/rt_linux_index.html)