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Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!news.uoknor.edu!ns1.nodak.edu!netnews.nwnet.net!news.clark.edu!spool.mu.edu!howland.reston.ans.net!cs.utexas.edu!swrinde!sgiblab!cs.uoregon.edu!news.uoregon.edu!usenet.coe.montana.edu!bsd.coe.montana.edu!nate From: nate@bsd.coe.montana.edu (Nate Williams) Newsgroups: comp.os.386bsd.misc Subject: Re: NetBSD on cheap boxes Date: 24 Jan 1994 19:26:22 GMT Organization: Montana State University - Bozeman MT Lines: 32 Message-ID: <2i17cu$n6m@pdq.coe.montana.edu> References: <2h2u3kINN6o3@ymir.cs.umass.edu> <GLASS.94Jan14170432@sun-lamp.postgres.Berkeley.EDU> <CJpoL6.BIx@veda.is> <PF51-V$@b-tech.uucp> NNTP-Posting-Host: bsd.coe.montana.edu In article <PF51-V$@b-tech.uucp>, Jon Zeeff <jon@b-tech.ann-arbor.mi.us> wrote: >This brings up a feature that too many systems seem to lack - some kind of >watchdog timer. Having seen a couple of systems go into this pingable, but >otherwise dead state, I'd like to see the kernel do some testing on the >proper functioning of the system and reboot if it is not correct. Easier said than done. Things like this are best done in hardware rather than software, since 1) Since the reason for the hanging state is not known, it's possible that the code you add would think the computer is still alive. 2) The watchdog code adds un-necessary overhead to the kernel and would most likely take up an IRQ that could be used for something else. 3) Hardware would do a very good job of this. Most of the time software would not be able to realize that it was screwed up. The kernel is hosed or the system would work, and your proposal to add software to check software assumes a kernel state that can't be verified. Telling a piece of software to check on itself w/out any hardware is like asking Congress to police itself. :-( Nate -- nate@bsd.coe.montana.edu | Freely available *nix clones benefit everyone, nate@cs.montana.edu | so let's not compete with each other, let's work #: (406) 994-4836 | compete with folks who try to tie us down to home #: (406) 586-0579 | proprietary O.S.'s (Microsloth) - Me