Date: Tue, 19 Dec 1995 10:29:45 +0100 (MET) From: J Wunsch <j@uriah.heep.sax.de> To: davidg@Root.COM Cc: dufault@hda.com, gibbs@freefall.freebsd.org, m.sapsed@bangor.ac.uk, hm@hcs.de, freebsd-bugs@freebsd.org Subject: Re: Problem with FreeBSD 2.1.0-RELEASE Message-ID: <199512190929.KAA02915@uriah.heep.sax.de> In-Reply-To: <199512190342.TAA02913@corbin.Root.COM> from "David Greenman" at Dec 18, 95 07:42:33 pm
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As David Greenman wrote:
>
> >I believe this is here in kern/vfs_bio.c:
> >
> >> int s = splbio();
> >>
> >> bh = BUFHASH(vp, blkno);
> >> bp = bh->lh_first;
> >>
> >> /* Search hash chain */
> >> while (bp) {
> >
> >where we go indirect on that bp.
>
> This is a "can't happen" panic. It can only happen if the CPU executes the
> instructions incorrectly. The assembly code is:
>
> ...
> movl _bufhashtbl(,%eax,4),%ebx
> testl %ebx,%ebx <- exit if bp is NULL
>From my analysis (after Hellmuth's bug report), it was just one line
above. I'm suspecting something with the BUFHASH() macro. Remember,
the ``fault virtual address''es are somewhat weird for all bug
reports, in this case it's 0x52. So it's not a NULL pointer, hence
not easy to check.
To recall it, the symptoms are that this panic happens for some people
with many cd drives, and _only_ when accessing the last drive.
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
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