From owner-freebsd-hackers Mon Mar 24 14:24:52 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id OAA13968 for hackers-outgoing; Mon, 24 Mar 1997 14:24:52 -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 OAA13958 for ; Mon, 24 Mar 1997 14:24:45 -0800 (PST) Received: (from uucp@localhost) by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id XAA27504; Mon, 24 Mar 1997 23:23:54 +0100 Received: (from j@localhost) by uriah.heep.sax.de (8.8.5/8.8.5) id WAA17633; Mon, 24 Mar 1997 22:00:23 +0100 (MET) Message-ID: <19970324220022.VH35420@uriah.heep.sax.de> Date: Mon, 24 Mar 1997 22:00:22 +0100 From: j@uriah.heep.sax.de (J Wunsch) To: hackers@FreeBSD.ORG Cc: bmcgover@cisco.com (Brian McGovern) Subject: Re: "double fault" message References: <199703241702.MAA00456@bmcgover-pc.cisco.com> X-Mailer: Mutt 0.60_p2-3,5,8-9 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: <199703241702.MAA00456@bmcgover-pc.cisco.com>; from Brian McGovern on Mar 24, 1997 12:02:52 -0500 Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk As Brian McGovern wrote: > I'm doing some kernel hacking, and my device driver is now getting the > messge 'panic: double fault', and rebooting. Can anyone let me know > what a 'double fault' is, so I can go looking for it? Thanks. Well, it's two faults in a row. But you already knew this, did you? :-) I think it might happen if you trash the kernel stack. The fault handler than attempts to run on this stack again, and triggers another fault. This will finally call the double fault handler, which i believe runs on its own small stack. -- 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. ;-)