Girish Wadhwani wrote: > > I was wondering about Adeos's roadmap. Right now I see > three uses of Adeos: > 1, Real time capabilities for Linux > 2, Clustering for Linux and > 3, Running multiple instances of Linux on the same > machine. > > Which of these is the project working towards? I there > an explicit roadmap towards any? I particular I am > interested in 3 and ways to possibly achieve it. I > think this would be useful to a lot of people. >
I would say #1, #3 then #2 since being able to run multiple copies of Linux first would hopefully pave the way to efficient SMP clustering over Adeos. Seeking #1 was IMHO the fastest path to get a functional and stable base to build onto. Once it's rock-solid for stressed real-time systems running along Linux, we should have a reasonable confidence for other kinds of use. #1 is no more experimental since we already had some positive feedback from demanding projects such as RTAI, Xenomai, or some company-lead efforts who succeeded in coupling Adeos to their in-house real-time kernel. The real problem now is the portability issue: Adeos is x86-only, and this is bad, it sounds as a lack of maturity at the very least. I hope the recent modularization effort will be an incentive to port it to other archs. However, this problem does not preclude us from initiating #3 now. > One approach would be to have a VMM and virtualize all > resources. This would involve the overhead of "world > switches" to the host OS and virtualization (with the > VMM running as an application on the host OS). You > would land up with something like VMWare and plex86 > which would have little value. > Agreed. I would rather call for a sound compromise between functionality and performance, keeping the wild horse of virtualization in manageable bounds. > The other approach would be the one mentioned in the > clustering paper i.e. make Linux aware of Adeos. This > brings up the question of how to get two or more > instances share resources and co-operate. A major > problem would be devices. Without virtualization, it > would invlove a huge number of changes to drivers, > making it difficult to develop and maintain, if one > were to support all the devices that Linux currently > does. In this case the purpose of Adeos would be to > multiplex access between multiple instances, which > would be aware of each other and avoid stepping on eac > others toes. The upside would be that you would have > significant performance advantages over the VMM > method. > I like the idea of giving exclusive control over the devices on a per-domain/os basis instead of trying to share them at all cost. It sounds more natural and less invasive. > Any thoughts on this? Or am I completely off the mark? > The information I found on the Adeos papers did not go > into much detail as to how things would be implemented > Yes, but at least they were well-written enough so that even _I_ had been able to understand them and implement something that resembles Karim's idea... So there's definitely room for unbounded hope! :o> Philippe.
