On 2009-03-12, Michael Schnell <mschn...@lumino.de> wrote: > >> I am looking at various realtime linux solutions for use in a >> personal embedded application. I understand that uCLinux is >> not a RTOS, but I have read posts on the Internet talking >> about using RATI with uCLinux. In particular I am looking at >> the Microblaze and Blackfin architectures.
> As you are interested in an FPGA based processor, you might > consider NIOS as well. We have a very active community > (http://sopc.et.ntust.edu.tw/cgi-bin/mailman/listinfo/nios2-dev). > > Re. realtime stuff, I feel that the the more "modern" way than > RTAI and similar things is using multiple "(Operating).System" > simultaneously by means of virtualization or multiple > processors/threads. Um, isn't that what RTAI does -- run the linux kernel on a virtualized processor? > With Microblaze or NIOS you can either implement a second > processor in the FPGA Add another processor? I think you misspelled "the more expensive way". ;) As one of my friends used to say: "the only thing worse than a product based on a microprocessor is one based on two of them." > or do the hard realtime stuff in hardware (if same can be > reduced to very simple functions). That last qualification is an important one. When I've asked in the NIOS forums about RTAI or other ways to control latency on the NIOS/Linux platform, the answer is always "do it in hardware!". That's fine if you have to toggle pin B whenever pin A changes, but for things like replying to a message on a TCP connection such advice is utterly useless. Not only does NIOS lack RTAI/Xenomi support, it doesn't even have NPTL support. That means that scheduling of threads is being done by user-space code. Yes, that results in really bad scheduling latencies (on the order of 5-10ms in my experience). -- Grant Edwards grante Yow! The Osmonds! You are at all Osmonds!! Throwing up visi.com on a freeway at dawn!!! _______________________________________________ uClinux-dev mailing list uClinux-dev@uclinux.org http://mailman.uclinux.org/mailman/listinfo/uclinux-dev This message was resent by uclinux-dev@uclinux.org To unsubscribe see: http://mailman.uclinux.org/mailman/options/uclinux-dev
