Date: Wed, 28 Jun 2006 15:34:59 +0100 (BST) From: Robert Watson <rwatson@FreeBSD.org> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-acpi@freebsd.org, freebsd-stable@freeBSD.org, Pete French <petefrench@ticketswitch.com> Subject: Re: FreeBSD 6.x CVSUP today crashes with zero load ... Message-ID: <20060628153222.I65342@fledge.watson.org> In-Reply-To: <20060626110636.I1114@ganymede.hub.org> References: <E1FuYsL-000HT3-H2@dilbert.firstcallgroup.co.uk> <20060626100949.G24406@fledge.watson.org> <20060626081029.L1114@ganymede.hub.org> <20060626140333.M38418@fledge.watson.org> <20060626110636.I1114@ganymede.hub.org>
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On Mon, 26 Jun 2006, Marc G. Fournier wrote: >> I think this is a useful activity, especially if you've already run >> extensive memory testing on the box. If you haven't yet done that, I >> encourage you to take a break from buildworld's and make sure the memory >> tests pass. I spent several months on and off trying to track down a bug a >> few years ago, which turned out to be a one bit error in memory on the box. >> It would appear and disappear based on how the memory page was used -- for >> debugging kernels, it consistently got mapped to padding in the kernel's >> bss. For non-debugging kernels, it typically manifested in other usable >> kernel momory. Changes in kernel versions would move the bit around kernel >> memory and user memory, resulting in hard to debug failure modes. I wish >> I'd run the memory test earlier, but the lesson is clear! > > Is there something that I can run *from* FreeBSD, remotely, to do this? Not that I know of. In the past, the discussion has been held about adopting a memory tester into the boot loader, which is almost certainly the right place to put it (before VM kicks off and we load many megabytes of critical data structures, etc). Some hands to make this happen would be most welcome. Robert N M Watson Computer Laboratory University of Cambridge
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