From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: Announcing Trapfs: a small lookup trapping filesystem, like autofs and devfs Date: Mon, 1 Nov 2004 21:43:53 +0000 Message-ID: <20041101214353.GA14876@mail.shareable.org> References: <200411021033.iA2AXBq10563@freya.yggdrasil.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, michael.waychison@sun.com, thockin@sun.com Return-path: Received: from mail.shareable.org ([81.29.64.88]:63466 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S321889AbUKAVnz (ORCPT ); Mon, 1 Nov 2004 16:43:55 -0500 To: "Adam J. Richter" Content-Disposition: inline In-Reply-To: <200411021033.iA2AXBq10563@freya.yggdrasil.com> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Adam J. Richter wrote: > Trapfs can also be used to provide create-on-demand device file > functionality for some non-devfs systems. I understand udev is the "new" way to create device files when devices are attached. It works fine for real devices. However, udev's weak point is that it won't create devices like "/dev/ppp" and "/dev/net/tun0" until you load their respective modules... and you usually want an attempt to load those devices to cause the modules to be loaded. That's why on my laptop, when I want to run pppd, I have to do "modprobe ppp_async" first. There's an ugly workaround where the entire contents of /dev are stored in a .tar.bz2 file which is restored at boot, including those kinds of device nodes, but it is very ugly because that file invariably ends up containing a lot of devices that you don't want, and duplicating a lot of the settings in udev's config files. When using that .tar.bz2, there isn't a lot of point in using udev at all. It would be nice if opening a non-existent file in /dev would trigger a hotplug/udev event - but otherwise have a perfectly normal tmpfs-like filesystem. IMHO that would fix udev nicely. Is trapfs suitable for that? -- Jamie