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Newsgroups: comp.os.386bsd.bugs Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!gatech!concert!sas!mozart.unx.sas.com!torpid.unx.sas.com!sastdr From: sastdr@torpid.unx.sas.com (Thomas David Rivers) Subject: Re: FreeBSD, fd0d: hard error Sender: news@unx.sas.com (Noter of Newsworthy Events) Message-ID: <Cwqnwy.AAs@unx.sas.com> Date: Mon, 26 Sep 1994 13:24:34 GMT References: <34lk6g$d44@orion.cc.andrews.edu> <CwCMrD.4p8@sneaky.lonestar.org> <364oj6INNka5@bonnie.sax.de> Nntp-Posting-Host: torpid.unx.sas.com Organization: SAS Institute Inc. Lines: 32 In article <364oj6INNka5@bonnie.sax.de> j@uriah.sax.de (J Wunsch) writes: >gordon@sneaky.lonestar.org (Gordon Burditt) writes: > >>Adaptec's EZ-SCSI manuals note that the default bus-on and bus-off >>times on the AHA1542-whatever are long enough to interfere with >>floppy or floppy-tape I/O due to DMA starvation. I'd expect >>that the error codes would reflect DMA underrun (writes) or >>overrun (reads), which I'm not seeing in the posts, but maybe >>there is a problem with error reporting or retry logic. > >Error reportings should be as accurate as the underlying FDC is. > >As far as i remember, *BSD does not use the default Adaptec DMA bus >timings. F.y.i. This changed in FreeBSD 1.1.5. It now does use the default bus timings, set by the jumpers on the card. This can bite you if you set the jumpers to be 'really fast' and the kernel test chose a slower bus on time. When moving to FreeBSD 1.1.5; the kernel test is no longer performed, and you wind up using these 'really fast' settings. Which probably won't work (you'll get lots of weird disk problems, etc...) > Anyway, there's still an interference between heavy SCSI >activity and the floppy. Hence the DMA overruns (the FDC has only an >overrun flag, which is also reported on underruns) are caught inside >the driver and silently retried. This is not one of the latest >changes, it did already exist in FreeBSD 1.1. - Dave Rivers - -- Imagine Whirled Peas.