From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <52204A62.7040005@siemens.com> Date: Fri, 30 Aug 2013 09:31:46 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <521F409D.4070507@siemens.com> In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] Virtualization with Xenomai List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Asier Cc: xenomai@xenomai.org On 2013-08-30 09:11, Asier wrote: > Jan, Nicolas, > > Thank you for your help: > >> Third option may be even more interesting (provided you really want to >> use Windows for the UI): Run Xenomai on the host and combine it with KVM >> to host another OS. This works fine with latest ipipe for 3.8 when RT >> tasks and the QEMU process (that uses KVM) are on separate CPUs, I just >> heard of issues (couldn't reproduce yet) when they share a CPU. >> > If I am not wrong, KVM runs on top of Linux, and then Windows on top of it. > Isn't it too much overhead? Isn't it better to use a Type 1 virtualization? Type 1 vs. type 2 is usually just marketing nonsense. You can do device pass-through with KVM as well, thus removing most of the I/O virtualization overhead, achieving near-native performance. Moreover, in contrast to several other hypervisors, KVM can benefit a lot from its architectural advantage to run hosted on Linux which reduced context switches on x86. > When you say separate CPUs, do you mean separate cores? Usually, this means cores (on a single-socket system). > >> Virtualizing your RT workload won't make things faster, naturally. >> Depending on the hypervisor architecture and hardware capabilities, it >> may not be measurable. >> > So, do you mean that, even though the system may be slower, the real-time > response will run smoothly? No general rule, depends on your hypervisor. > >> But I would refrain from such stacking unless there is a real need >> (which I do not see for your setup). >> > My plan for the mid term is to run the user interface (HMI) and the > real-time applications in one board. Meanwhile, I need to update my HMI and > I want to use a complete Linux distribution (one with a desktop manager) > with Xenomai. However, I may finally be forced to use Windows (3rd party > programs) and, when porting my system to one board, I would need some > virtualization tools. > > Yesterday, I wrote another e-mail asking for opinions about a Linux > distribution with Xenomai, or about any experience with the Yocto project > and Xenomai. Has anyone got any information regarding this? There are debian packages for Xenomai, but it is trivial to build it for any distro of your preference. Yocto-wise: ELDK, which should come with Xenomai support IIRC, is based on yocto these days. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux