From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1IVuDr-000680-4q for user-mode-linux-devel@lists.sourceforge.net; Thu, 13 Sep 2007 12:19:31 -0700 Received: from scorpius.cttc.es ([84.88.62.197]) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1IVuDq-0000jV-7Q for user-mode-linux-devel@lists.sourceforge.net; Thu, 13 Sep 2007 12:19:31 -0700 Message-ID: <46E9A824.3010808@cttc.es> Date: Thu, 13 Sep 2007 23:14:12 +0200 From: =?ISO-8859-1?Q?Ferm=EDn_Gal=E1n_M=E1rquez?= MIME-Version: 1.0 References: <46DDAD83.4030004@cttc.es> <20070912203002.GA9725@c2.user-mode-linux.org> <46E88B64.7090705@cttc.es> <200709131909.01286.blaisorblade@yahoo.it> In-Reply-To: <200709131909.01286.blaisorblade@yahoo.it> Subject: [uml-devel] (Solved) Hanging using 'iptables -L' in UML vm booted with con0=pts List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: user-mode-linux-devel-bounces@lists.sourceforge.net Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net To: user-mode-linux-devel@lists.sourceforge.net Cc: =?ISO-8859-1?Q?David_Fern=E1ndez?= Hi, After some more debugging I think I've solved the problem (at least :) = An explanation follows. First, although apparently it seemed that the modules causing the = problem were the ones related with networking (as David Fern=E1ndez said = in his mail) that assumption was wrong. In fact, the modules causing the = problem are the ones that print some message in the "kernel message = buffer" (I don't know what is the right name, but I'm referring to the = message log that appears when the dmesg command is used) when modprobe = load them. For example, ip_tables prints something like "ip_tables: (C) = 2000-2006 Netfilter Core Team". The solution to the problem is using con1 instead of con0, I mean: ./linux ubd0=3D/tmp/root_fs_debug con=3Dnull con1=3Dpts uml_dir=3D/tmp umid= =3Drun instead of ./linux ubd0=3D/tmp/root_fs_debug con=3Dnull con1=3Dpts uml_dir=3D/tmp umid= =3Drun In that case you can 'iptables -L' works without problems. Why? When the module is loaded it prints its message not only in the = internal kernel message buffer but also in con0 (this can be checked = running simply "./linux ubd0=3D/tmp/root_fs_debug", without con=3D = redirectors). When con0 is redirected to null (con0=3Dnull) there is no = problem, but if con0 is redirected to a pts (con0=3Dpts) I guess that, in = the moment of printing the message, some problem occurs with the output = (as Jeff suggest in its mail) thus causing the vm hang. This explains also why putting the module in /etc/modules works. The = loading of the list of modules in /etc/modules is performed before UML = assign virtual console to pts devices (the sequence can be checked = observing the booting log). I think that my solution is more a workaround that a definitive = solution. Why when con0 is assigned to a pts modules can not (because of = it hangs the vm) print its message but when it is assigned to null it = works? Is there a bug in the UML kernel that need to be fixed? Or maybe = the bug is in modprobe? I leave the question open for the experts in the = UML internals... :) Regarding the tests suggested by Paolo: > Please try logging in via SSH and reproducing the problem and the stacktr= ace, = > and also removing con=3Dnull - also have you double checked con=3Dnull is= ok = > (maybe it was con=3Dnone, I'm not sure). I'm not sure screen is perfectly= safe = > to use (it should be). Do you really need that I perform these test or considers the report = above is enough? If it's really needed I can do them, but it would take = me some time (and maybe now it isn't a good idea because of they won't = provide additional useful information :) Best regards, -------------------- Ferm=EDn Gal=E1n M=E1rquez CTTC - Centre Tecnol=F2gic de Telecomunicacions de Catalunya Parc Mediterrani de la Tecnologia, Av. del Canal Ol=EDmpic s/n, 08860 Castelldefels, Spain Room 1.02 Tel : +34 93 645 29 12 Fax : +34 93 645 29 01 Email address: fermin dot galan at cttc dot es ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel