Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753887AbXFNPXO (ORCPT ); Thu, 14 Jun 2007 11:23:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751958AbXFNPXA (ORCPT ); Thu, 14 Jun 2007 11:23:00 -0400 Received: from aa013msr.fastwebnet.it ([85.18.95.73]:55244 "EHLO aa013msr.fastwebnet.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752176AbXFNPXA (ORCPT ); Thu, 14 Jun 2007 11:23:00 -0400 Date: Thu, 14 Jun 2007 17:22:34 +0200 From: Paolo Ornati To: Matthew Cc: linux-kernel@vger.kernel.org Subject: Re: /dev/loop* devices not appearing in /dev (at least since 2.6.22-rc3*) Message-ID: <20070614172234.7f636307@localhost> In-Reply-To: References: <20070614145206.58fdec91@localhost> X-Mailer: Claws Mail 2.9.1 (GTK+ 2.10.11; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1736 Lines: 53 On Thu, 14 Jun 2007 16:10:44 +0200 Matthew wrote: > I just tried out > > modprobe loop max_loop=32 > > output of dmesg is: > > [ 457.607575] loop: the max_loop option is obsolete and will be > removed in March 2008 > [ 457.607578] loop: module loaded > > but there are NO loop devices in /dev: > > ls -l /dev/ | grep loop > still shows nothing, strange ... it's not strange, with your kernel version "max_loop" will just limit the max number of loop devices at most. This is what happens with the mentioned patch (-rc5 and later): + /* + * loop module now has a feature to instantiate underlying device + * structure on-demand, provided that there is an access dev node. + * However, this will not work well with user space tool that doesn't + * know about such "feature". In order to not break any existing + * tool, we do the following: + * + * (1) if max_loop is specified, create that many upfront, and this + * also becomes a hard limit. + * (2) if max_loop is not specified, create 8 loop device on module + * load, user can further extend loop device by create dev node + * themselves and have kernel automatically instantiate actual + * device on-demand. + */ So with this patch "max_loop=32" will create 32 loop devices... but then it doesn't allow more of them. Without options it creates 8 and you (or some userspace tool) can add more dynamically. -- Paolo Ornati Linux 2.6.22-rc4-cfs-v16-g47932c49 on x86_64 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/