We would like to learn Xenomai using this website (http://www.cs.ru.nl/lab/xenomai/) at beginning.
The aim of this presentation is the introduction of Xenomai 3.The main contents is following：
- Project introduction
- Co-Kernel technology, now and then
- Xenomai 3 for native Linux
- Improving co-kernel integration
Project introduction
First we learned the definition of Xenomai and then history of Xenomai development and the contributors are presented.
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a fork of RTAI RT embedded Linux has two main approaches,one is called pre-emptible kernel(RT_PREEMPT) and the other is named dual-kernel approach(RTAI). |
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Definition of Xenomai ,portability( transportability , handiness ) |
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ADEOS:Adaptive domain environment for operating systems; what is the meaning of POSIX-centric?( portable operating system interface) |
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It seems very useful.I have never known Xenomai could be widely applied in the Robotics research before. |
Co-Kernel technology, now and then
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IRQ(Interrupt Request);I am not sure how does this figure show co-kernel.Here is only one kernel in the graph.;Interrupt and Trap Dispatching –from Adeos to I-pipe(interrupt pipe) CoreWe could use ipipe_raise_irq() to push interrupt into pipeline |
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native rtdm posix psos+ uitron vrtx vxworks;what is the meaning of ‘skin’ |
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Xenomai 3 dual kernel configuration : Cobalt We use Cobalt core to mange RT task;Dispatching problem Both Cobalt and libc provide POSIX implementations?How do RT application pick the right one? |
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RTDM |
Xenomai 3 dual kernel configuration : Cobalt:
多一個 priority 比 linux 還高叫 cobalt 的 core 去處理 real-time 的事情，提供不同的 real-time API 給不同的 applications 使用。並且利用Optimistic interrupt protection 機制減少 changing the interrupt mask，一般的機制在每次進入critical section時都要interrupt mask，而Optimistic interrupt protection可以不用。而real-time 在意的 “deadline”，實際上就是探討 latency(latency 越大，系統越難在時限內完成完成高優先權任務，自然即時能力就越差)，而 latency 很大的來源則是 interrupt handling。
Xenomai 3 for native Linux
The paper which we have read mentioned that they chose to develop an environment based on dual-kernel approach.
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The disadvantages or limitations of PREEMPT-RT |