From owner-freebsd-hackers Mon Feb 10 00:50:41 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id AAA19439 for hackers-outgoing; Mon, 10 Feb 1997 00:50:41 -0800 (PST) Received: from sax.sax.de (sax.sax.de [193.175.26.33]) by freefall.freebsd.org (8.8.5/8.8.5) with SMTP id AAA19434 for ; Mon, 10 Feb 1997 00:50:38 -0800 (PST) Received: (from uucp@localhost) by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id JAA11670 for freebsd-hackers@freebsd.org; Mon, 10 Feb 1997 09:50:35 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.8.5/8.6.9) id JAA18664; Mon, 10 Feb 1997 09:29:05 +0100 (MET) Message-ID: Date: Mon, 10 Feb 1997 09:29:04 +0100 From: j@uriah.heep.sax.de (J Wunsch) To: freebsd-hackers@freebsd.org (FreeBSD hackers) Subject: Re: Copious information on panic: ffs_valloc: dup alloc - IDEAS??? References: <199702091818.NAA23739@lakes.water.net> <32FE7015.2F1CF0FB@whistle.com> X-Mailer: Mutt 0.55-PL10 Mime-Version: 1.0 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) In-Reply-To: <32FE7015.2F1CF0FB@whistle.com>; from Julian Elischer on Feb 9, 1997 16:47:17 -0800 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk As Julian Elischer wrote: > if you make it have 2 heads, this code will be enabled > again and we'll lose the effect.. > you could HEAR the difference when we went to 1 head.. But unfortunately, you could also _see_ the panics afterwards. :-( Go and re-read Thomas's original article. It's not simply summarizable in three sentences, sorry. The only summary is this: ntracks == 1 causes cgmask = 0xffffffff. The latter seems to cause block miscalculations in the filesystem code. As for the exact chain of miscalculations, refer to Message-ID <199702090226.VAA22081@lakes.water.net>. If you need something to prove this, setup a small MFS, and beat upon it. I can send you my ``mount /dev/null for MFS'' patches, or maybe, i simply commit them. They are basically required anyway to create a MFS on a diskless station (where you don't have a swap partition to template the MFS parameters from). -- 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. ;-)