From owner-freebsd-hackers@FreeBSD.ORG Thu Jul 11 13:30:44 2013 Return-Path: Delivered-To: hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id ACBB45D2 for ; Thu, 11 Jul 2013 13:30:44 +0000 (UTC) (envelope-from lars@e-new.0x20.net) Received: from mail.0x20.net (mail.0x20.net [IPv6:2001:aa8:fffb:1::3]) by mx1.freebsd.org (Postfix) with ESMTP id 707B11D72 for ; Thu, 11 Jul 2013 13:30:44 +0000 (UTC) Received: from e-new.0x20.net (mail.0x20.net [IPv6:2001:aa8:fffb:1::3]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.0x20.net (Postfix) with ESMTPS id 640086A6004; Thu, 11 Jul 2013 15:30:42 +0200 (CEST) Received: from e-new.0x20.net (localhost [127.0.0.1]) by e-new.0x20.net (8.14.7/8.14.7) with ESMTP id r6BDUgYK098739; Thu, 11 Jul 2013 15:30:42 +0200 (CEST) (envelope-from lars@e-new.0x20.net) Received: (from lars@localhost) by e-new.0x20.net (8.14.7/8.14.7/Submit) id r6BDUetl098592; Thu, 11 Jul 2013 15:30:40 +0200 (CEST) (envelope-from lars) Date: Thu, 11 Jul 2013 15:30:40 +0200 From: Lars Engels To: asomers@gmail.com Subject: Re: Kernel dumps [was Re: possible changes from Panzura] Message-ID: <20130711133040.GO88288@e-new.0x20.net> References: <9890DFF1-892A-4DCA-9E33-B70681154F43@mail.turbofuzz.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SDZNRjzUoAX9KAL/" Content-Disposition: inline In-Reply-To: X-Editor: VIM - Vi IMproved 7.3 X-Operation-System: FreeBSD 8.4-RELEASE User-Agent: Mutt/1.5.21 (2010-09-15) Cc: hackers@freebsd.org, Julian Elischer , Jordan Hubbard X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Jul 2013 13:30:44 -0000 --SDZNRjzUoAX9KAL/ Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 10, 2013 at 02:04:17PM -0600, asomers@gmail.com wrote: > On Wed, Jul 10, 2013 at 12:57 PM, Jordan Hubbard = wrote: > > > > On Jul 10, 2013, at 11:16 AM, Julian Elischer wro= te: > > > >> My first candidates are: > > > > Those sound useful. Just out of curiosity, however, since we're on > > the topic of kernel dumps: Has anyone even looked into the notion > > of an emergency fall-back network stack to enable remote kernel > > panic (or system hang) debugging, the way OS X lets you do? I can't > > tell you the number of times I've NMI'd a Mac and connected to it > > remotely in a scenario where everything was totally wedged and just > > a couple of minutes in kgdb (or now lldb) quickly showed that > > everything was waiting on a specific lock and the problem became > > manifestly clear. > > > > The feature also lets you scrape a panic'd machine with automation, > > running some kgdb scripts against it to glean useful information for > > later analysis vs having to have someone schlep the dump image > > manually to triage. It's going to be damn hard to live without this > > now, and if someone else isn't working on it, that's good to know > > too! >=20 > I don't doubt that it would be useful to have an emergency network > stack. But have you ever looked into debugging over firewire? We've > had success with it. All of our development machines are connected to > a single firewire bus. When one panics, we can remotely debug it with > both kdb and ddb. It's not ethernet , but it's still much faster than > a serial port. > https://wiki.freebsd.org/DebugWithDcons Debugging over Firewire may be very nice to use, but Firewire is dead while every single device nowadays has a network interface, admittedly it's often wireless. --SDZNRjzUoAX9KAL/ Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (FreeBSD) iEYEARECAAYFAlHes4AACgkQKc512sD3afg29QCdGEG7bQhxyoI6W8TyyOYvg0Wx 0HcAnj3R3pX1GLuO6zZW3XmLQVQOO5G9 =olYf -----END PGP SIGNATURE----- --SDZNRjzUoAX9KAL/--