[bootlin/training-materials updates] master: First Xenomai updates (23f92e4f)
Michael Opdenacker
michael.opdenacker at bootlin.com
Fri Jun 5 10:17:01 CEST 2020
Repository : https://github.com/bootlin/training-materials
On branch : master
Link : https://github.com/bootlin/training-materials/commit/23f92e4f089cb65e2d824abbbfabde66f298290d
>---------------------------------------------------------------
commit 23f92e4f089cb65e2d824abbbfabde66f298290d
Author: Michael Opdenacker <michael.opdenacker at bootlin.com>
Date: Fri Jun 5 10:17:01 2020 +0200
First Xenomai updates
- Still missing updates about userspace building
Signed-off-by: Michael Opdenacker <michael.opdenacker at bootlin.com>
>---------------------------------------------------------------
23f92e4f089cb65e2d824abbbfabde66f298290d
.../sysdev-realtime/adeos-interrupt-pipeline1.jpg | Bin 97342 -> 0 bytes
.../sysdev-realtime/adeos-interrupt-pipeline1.png | Bin 64857 -> 0 bytes
slides/sysdev-realtime/sysdev-realtime.tex | 87 +++++++--------------
3 files changed, 30 insertions(+), 57 deletions(-)
diff --git a/slides/sysdev-realtime/adeos-interrupt-pipeline1.jpg b/slides/sysdev-realtime/adeos-interrupt-pipeline1.jpg
deleted file mode 100644
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diff --git a/slides/sysdev-realtime/adeos-interrupt-pipeline1.png b/slides/sysdev-realtime/adeos-interrupt-pipeline1.png
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diff --git a/slides/sysdev-realtime/sysdev-realtime.tex b/slides/sysdev-realtime/sysdev-realtime.tex
index a4575704..148dcce2 100644
--- a/slides/sysdev-realtime/sysdev-realtime.tex
+++ b/slides/sysdev-realtime/sysdev-realtime.tex
@@ -1036,14 +1036,17 @@ cat /sys/kernel/tracing/tracing_max_latency
RTOS.
\item Initial goals: facilitate the porting of programs to GNU /
Linux.
- \item Initially related to the RTAI project (as the RTAI / fusion
- branch), now independent.
- \item Skins mimicking the APIs of traditional RTOS such as
- VxWorks, pSOS+, and VRTXsa as well as the POSIX API, and a
- “native” API.
- \item Aims at working both as a co-kernel and on top of
- PREEMPT\_RT in future upstream Linux versions.
- \item Will never be merged in the mainline kernel.
+ \item Skins mimicking the APIs of the VxWorks and pSOS traditional
+ real-time operating systems, as well as the POSIX API, and offering
+ a “native” API too.
+ \item Offers two solutions:
+ \begin{itemize}
+ \item {\em Cobalt}: (like {\bf Co}-kernel), using
+ a micro-kernel dedicated to running real-time tasks.
+ This will never be merged in the mainline kernel.
+ \item {\em Mercury}: (like {\bf Mer}ge), based on the mainline
+ kernel with PREEMPT\_RT.
+ \end{itemize}
\end{itemize}
\column{0.2\textwidth}
\includegraphics[width=\textwidth]{slides/sysdev-realtime/xenomai.png}
@@ -1051,48 +1054,17 @@ cat /sys/kernel/tracing/tracing_max_latency
\end{frame}
\begin{frame}
- \frametitle{Xenomai architecture}
+ \frametitle{Xenomai Cobalt architecture}
\begin{center}
\includegraphics[height=0.8\textheight]{slides/sysdev-realtime/xenomai-architecture.pdf}
\end{center}
\end{frame}
-\begin{frame}
- \frametitle{The Adeos interrupt pipeline abstraction}
- \begin{itemize}
- \item From the Adeos point of view, guest OSes are prioritized
- domains.
- \item For each event (interrupts, exceptions, syscalls, etc...), the
- various domains may handle the event or pass it down the pipeline.
- \end{itemize}
- \begin{center}
- \includegraphics[width=0.7\textwidth]{slides/sysdev-realtime/adeos-interrupt-pipeline1.png}
- \end{center}
- \tiny Image credits: Xenomai documentation
-\end{frame}
-
-\begin{frame}
- \frametitle{Xenomai features}
- \begin{itemize}
- \item Factored real-time core with skins implementing various
- real-time APIs
- \item Seamless support for hard real-time in user space
- \item No second-class citizen, all ports are equivalent feature-wise
- \item Xenomai support is as much as possible independent from the
- Linux kernel version (backward and forward compatible when
- reasonable)
- \item Each Xenomai branch has a stable user/kernel ABI
- \item Timer system based on hardware high-resolution timers
- \item Per-skin time base which may be periodic
- \item RTDM skin allowing to write real-time drivers
- \end{itemize}
-\end{frame}
-
\begin{frame}
\frametitle{Xenomai user space real-time support}
\begin{itemize}
- \item Xenomai supports real-time in user space on 5 architectures,
- including 32 and 64 bits variants.
+ \item Supported architectures are the ones supported by the {\em
+ ipipe} patch: arm, arm64, blackfin, powerpc, x86
\item Two modes are defined for a thread
\begin{itemize}
\item the primary mode, where the thread is handled by the Xenomai
@@ -1147,8 +1119,6 @@ cat /sys/kernel/tracing/tracing_max_latency
\item Character-style device drivers
\item Network-style device drivers
\end{itemize}
- \item See the whitepaper on\\
- \url{https://www.xenomai.org/documentation/xenomai-2.6/pdf/RTDM-and-Applications.pdf}
\item Current notable RTDM based drivers:
\begin{itemize}
\item Serial port controllers;
@@ -1157,21 +1127,26 @@ cat /sys/kernel/tracing/tracing_max_latency
\item Analogy, fork of the Comedi project, drivers for acquisition cards.
\end{itemize}
\end{itemize}
+ \url{https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__rtdm.html}
\end{frame}
\subsection{Setting up Xenomai}
-\begin{frame}
- \frametitle{How to build Xenomai}
+\begin{frame}[fragile]
+ \frametitle{How to build the Xenomai kernel (Cobalt)}
\begin{itemize}
\item Download Xenomai sources at
\url{https://xenomai.org/downloads/xenomai/stable/latest/}
- \item Download one of the Linux versions supported by this release\\
- (see \code{ksrc/arch/<arch>/patches/})
- \item Since version 2.0, split kernel/user building model.
- \item Kernel uses a script called \code{script/prepare-kernel.sh}
- which integrates Xenomai kernel-space support in the Linux
- sources.
+ \item Download the latest {\bf i-pipe} patch for your architecture:\\
+ \url{https://xenomai.org/downloads/ipipe/}
+ \item Download the corresponding kernel.org version
+ \item Xenomai offers a script to patch your kernel. Example (arm):
+\begin{verbatim}
+./scripts/prepare-kernel.sh \
+ --linux=../linux-4.19.124 \
+ --ipipe=../ipipe-core-4.19.124-cip27-arm-09.patch
+ --arch=arm \
+\end{verbatim}
\item Run the kernel configuration menu.
\end{itemize}
\end{frame}
@@ -1184,7 +1159,7 @@ cat /sys/kernel/tracing/tracing_max_latency
\end{frame}
\begin{frame}
- \frametitle{Xenomai user space support}
+ \frametitle{How to build Xenomai user space}
\begin{itemize}
\item User space libraries are compiled using the traditional autotools
\begin{itemize}
@@ -1265,13 +1240,11 @@ ret = bind(s, (struct sockaddr *)&saddr, sizeof(saddr));
\end{frame}
\begin{frame}[fragile]
- \frametitle{The native API}
+ \frametitle{Alchemy: the native API}
Xenomai proposes its own API for developing real-time tasks
\begin{itemize}
\item {\small
- \url{https://xenomai.org/documentation/branches/v2.4.x/pdf/Native-API-Tour-rev-C.pdf}}
- \item Usable both in user space and kernel space. Development of
- tasks in user space is the preferred way.
+ \url{https://xenomai.org/documentation/xenomai-3/html/xeno3prm/group__alchemy.html}}
\item Xenomai developers find it a more coherent and more flexible API
than the POSIX API, and easier to learn and understand.
\item However, beware that programming with the POSIX API is much
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