This is only a little OT, but... If the modern kernels work out of the box on the Cortex-A8, then maybe real-time preemptive would work until RTAI has a port ready. IIRC, RT preemtion was running ~10us compared to ~4us on the same hardware. Those tests though are a few years old, so it might be better now. It would also be useful for RT applications which do not have as tight a tolerance.
EBo -- Matt Shaver <m...@mattshaver.com> said: > Taking this info into account, I'll get this board shipped to you > tomorrow! Dale made a nice level translator circuit to go from the > beagle's 3.3v i/o port to a 5v parallel port pinout, which I'll send > with the board. Also, I got an 8g sd card I'll send too that has debian > on it and a running EMC, albeit with no real time kernel. > > Thanks, > Matt > > On Thu, 2009-08-20 at 20:19 -0500, Jon Elson wrote: > > Matt Shaver wrote: > > > On Mon, 2009-08-17 at 12:55 -0500, Jon Elson wrote: > > > > > >> Ahh, some new news! Torsten Koschorrek, the rtai ARM maintainer, has > > >> volunteered to do an rtai port for the Cortex-A8! > > >> But, he is tied up right now, and won't be able to dig into it until > > >> next month. Still, that actually sounds pretty good, could be a LOT > > >> faster to have an expert working on it than the opposite - like me. So, > > >> there are two possible paths, here : > > >> > > >> One is to have rtai, but they seem to be stuck with a 2.6.20 kernel, > > >> which sounds awfully old. I wouldn't be surprised to find there is NO > > >> Beagle Board kernel that old. > > >> > > > > > > I haven't shipped the Beagle Board to you yet (general > > > procrastination/laziness/distractions, etc.). Should I send it to this > > > other guy instead? It sounds like, from this: > > > > > > http://mail.rtai.org/pipermail/rtai/2009-August/021925.html > > > > > > that their main holdup is hardware to work with. > > > > > > > > I'm not sure. There are now two people expressing interest, both out of > > the US, I think. Torsten is not going to have time to dig in > > for a little bit. And, I'm not too sure of the other guy's abilities or > > dedication to this project. Somebody not real familiar with the > > internals of > > RTAI would find this a hard project to dive right into, I would think. > > Meanwhile, I might get one running in user mode to start developing a > > parallel port emulator (mostly a bidirectional 8-bit port with 1.8 - 5 V > > logic level conversion and a little wrapper code to make it look as close > > to the PC parallel port as I can.) I really can't even begin to look at > > interfacing EMC2 to anything until I have a parallel port of some sort > > to work with. > > > > >> Another is to use the just-developed rt-linux patch from France to the > > >> 2.6.29 kernel. But, I don't know if there are any problems with using > > >> rt-linux. I gather we haven't used rt-linux for some years, now. I > > >> seem to recall there was extremely primitive support for printing > > >> messages and such from the kernel space. > > >> > > > > > > Is this a patch for the ARM arch? If so, it might be a quicker way to > > > go, assuming the rtlib support for rtlinux still works. > > > > > Yeah, that was the question I asked a couple days ago. I don't think > > anyone has used the rtlib stuff in a LONG time. > > The patch is for a 2.6.29 kernel on the Beagle Board, specifically! > > > > So, you had some version of Ubuntu running on the Beagle? How big an SD > > / MMC card did you get? Looking around, pretty much the largest MMC > > card I could find was 2 GB, is that enough for Ubuntu and EMC2? Also, > > there are several flavors of memory cards supported, are there > > performance differences in these? Compared to modern hard drives, these > > things look like they might have mediocre performance, like 20 > > mbits/second transfer rates. I didn't even realize these things were > > either 1 or 4 bits serial. > > > > Thanks, > > > > Jon > > > > ------------------------------------------------------------------------------ > Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day > trial. Simplify your report design, integration and deployment - and focus on > what you do best, core application coding. Discover what's new with > Crystal Reports now. http://p.sf.net/sfu/bobj-july > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > -- ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
