From owner-freebsd-hackers Tue Jun 6 00:02:26 1995 Return-Path: hackers-owner Received: (from majordom@localhost) by freefall.cdrom.com (8.6.10/8.6.6) id AAA05805 for hackers-outgoing; Tue, 6 Jun 1995 00:02:26 -0700 Received: from who.cdrom.com (who.cdrom.com [192.216.222.3]) by freefall.cdrom.com (8.6.10/8.6.6) with ESMTP id AAA05797 for ; Tue, 6 Jun 1995 00:02:25 -0700 Received: from irz301.inf.tu-dresden.de (irz301.inf.tu-dresden.de [141.76.1.11]) by who.cdrom.com (8.6.11/8.6.11) with SMTP id XAA13232 for ; Mon, 5 Jun 1995 23:54:28 -0700 Received: from sax.sax.de by irz301.inf.tu-dresden.de with SMTP (5.67b+/DEC-Ultrix/4.3) id AA01284; Tue, 6 Jun 1995 08:53:19 +0200 Received: by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id IAA16104 for freebsd-hackers@freebsd.org; Tue, 6 Jun 1995 08:53:19 +0200 Received: (from j@localhost) by uriah.heep.sax.de (8.6.11/8.6.9) id IAA06472 for freebsd-hackers@freebsd.org; Tue, 6 Jun 1995 08:42:59 +0200 From: J Wunsch Message-Id: <199506060642.IAA06472@uriah.heep.sax.de> Subject: Re: kernel page fault while doing tar to /dev/rft0 To: freebsd-hackers@freebsd.org (FreeBSD hackers) Date: Tue, 6 Jun 1995 08:42:58 +0200 (MET DST) Reply-To: freebsd-hackers@freebsd.org (FreeBSD hackers) In-Reply-To: <199506060230.TAA25146@gndrsh.aac.dev.com> from "Rodney W. Grimes" at Jun 5, 95 07:30:29 pm Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) 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 Content-Length: 1531 Sender: hackers-owner@freebsd.org Precedence: bulk As Rodney W. Grimes wrote: > > > ft is a pointer to the floppy t_y_pe structure. > > Ah.. okay, suggest we rename it to type then! fd->type->secsize makes > a lot more since when reading this code!!! Look into the code please, Rod: there's already something named `type' within struct fd_data, just one line above! (It's the drive type code, as opposed to the drive type data structure, describing drive geometry.) > > Patches should be reviewed by someone (if any :-) who is familiar with > > the code. > > Agreed, but it still fails on the fact the hunk is offset which means > the purson is not testing against -current code. Calm down. Steve always told that he's running 2.0R, and the bug has creeped in before 2.0. Furthermore, Steve was only reviewing my suggestion, which i've done based on -current. Back to the topic: anything regarding a floppy tape drive will not fall below the lines #if'ed. So it has been apparent to me that the bug must be somewhere in the variable initialization above. Since the panics experienced a NULL pointer dereferencation, fd->ft was the most suspect one. Beware that, unlike my first suggestion, it's not possible to move all those 5 lines (starting at line 1079 :) of variable initialization below the #if NFT > 0 block, since at least fdc (and hence fd and fdu) have to be initialized for the second check (tape already busy). -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ Never trust an operating system you don't have sources for. ;-)