From owner-freebsd-bugs Tue Dec 19 01:53:06 1995 Return-Path: owner-bugs Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id BAA04157 for bugs-outgoing; Tue, 19 Dec 1995 01:53:06 -0800 (PST) Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id BAA03935 for ; Tue, 19 Dec 1995 01:49:15 -0800 (PST) Received: from sax.sax.de by irz301.inf.tu-dresden.de (8.6.12/8.6.12-s1) with ESMTP id KAA20759; Tue, 19 Dec 1995 10:48:59 +0100 Received: by sax.sax.de (8.6.11/8.6.12-s1) with UUCP id KAA09414; Tue, 19 Dec 1995 10:48:58 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.6.12/8.6.9) id KAA02915; Tue, 19 Dec 1995 10:29:45 +0100 From: J Wunsch Message-Id: <199512190929.KAA02915@uriah.heep.sax.de> Subject: Re: Problem with FreeBSD 2.1.0-RELEASE To: davidg@Root.COM Date: Tue, 19 Dec 1995 10:29:45 +0100 (MET) Cc: dufault@hda.com, gibbs@freefall.freebsd.org, m.sapsed@bangor.ac.uk, hm@hcs.de, freebsd-bugs@freebsd.org Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <199512190342.TAA02913@corbin.Root.COM> from "David Greenman" at Dec 18, 95 07:42:33 pm X-Phone: +49-351-2012 669 X-Mailer: ELM [version 2.4 PL23] MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-bugs@freebsd.org Precedence: bulk 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. ;-)