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Path: sserve!manuel!munnari.oz.au!hp9000.csc.cuhk.hk!uakari.primate.wisc.edu!sdd.hp.com!elroy.jpl.nasa.gov!usc!sol.ctr.columbia.edu!destroyer!uunet!decwrl!netcomsv!mork!hasty From: hasty@netcom.com (Amancio Hasty Jr) Newsgroups: comp.unix.bsd Subject: Re: COM driver and X11 Keywords: COM X11 Message-ID: <9d8lvff.hasty@netcom.com> Date: 9 Jul 92 04:38:43 GMT References: <cproto.710554678@marsh> Organization: Netcom - Online Communication Services (408 241-9760 guest) Lines: 42 In article <cproto.710554678@marsh> cproto@marsh.cs.curtin.edu.au (Computer Protocol) writes: > >I'm running 386BSD (17/03/92) and experience silo overflows when >running a kermit filetransfer (2400 b/s) in background and anything >(even just a ls) in foreground. I get the silo overflows both with >the released com driver as well as with the latest post which is >supposedly fixing this problem. My COM port is implemented with a >NS16450 so I can't use the 16 byte FIFO supported in the latest >driver. But even with a NS16550 with the FIFO I doubt whether the >driver would keep up due to the TTY stuff it has to go through for >every received character (at 9600 b/s or higher). > >BTW I also experience the problem running X and moving the serial >mouse while just launching some X application. > Do you have my ast patches? Also, bear in mind that disk i/o is done at a high IPL level. So if you do a lot of disk i/o you will get com overflow for sure. To make matters worse there are couple areas in the kernel which don't restore back the ipl! >I think the driver should be really split into two parts. A lower >level driver which is handling the receive interrupts at a high >priority and a very short execution path. This part should write >received characters plus status into a circular buffer and then >cause some software interrupt to invoke the higher level driver >to do all the fancy TTY bits. > I am sick and tire of trying to make the com driver work, I arrived at the same conclusion as you. It will be nice if the rest of the set ipl and restore ipls in the system be balanced; also to lower the ipl of the disk i/o. >Before I start on this please let me know what you guys think ?!? > Let me know if I could help you. >Regards - Tibor Sashegyi (cproto@abel.cs.curtin.edu.au) > Cheers, Amancio