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Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!sgiblab!swrinde!cs.utexas.edu!uunet!brunix!cs.brown.edu!Mark_Weaver From: Mark_Weaver@brown.edu Subject: Re: Random seg. faults w/ NetBSD In-Reply-To: simonm@dcs.glasgow.ac.uk's message of Fri, 17 Dec 1993 13:24:05 GMT Message-ID: <MARK_WEAVER.93Dec18172426@tonto-slip9.cis.brown.edu> Sender: news@cs.brown.edu Reply-To: Mark_Weaver@brown.edu Organization: Brown University Department of Computer Science References: <CI6L86.3HJ@dcs.glasgow.ac.uk> Date: Sat, 18 Dec 1993 22:24:26 GMT Lines: 26 In article <CI6L86.3HJ@dcs.glasgow.ac.uk> simonm@dcs.glasgow.ac.uk (Simon Marlow) writes: > I've just bought a new motherboard (486/40 8M 256k write-back cache). > When running a compile job (compiling the kernel for instance) I get > random segmentation faults from the compiler. If I turn off the > external cache using setup, everything works fine. No amount of > fiddling with wait states and cache cycles seems to help while the > cache is on. The exact same NetBSD installation used to work fine > with my old 386/25 motherboard. > > I thought I'd consult the group before I send the board back. Does > anyone have a clue as to what might cause this? The problem is in the design of your new motherboard. DMA transfers do not automatically invalidate the cache on your board, which effectively means that much of the data being read from your disk seems to be getting corrupted. I have the same problem with my motherboard, but I don't mind too much. The speed difference isn't nearly as large as I'd expect, and this may be fixed at some point in the future. There is a fairly clean way to work around it in software; it just hasn't been done yet. Mark -------------------------------------------------------------------- Email: Mark_Weaver@brown.edu | Brown University PGP Key: finger mhw@cs.brown.edu | Dept of Computer Science