From owner-freebsd-hackers@FreeBSD.ORG Tue Jul 15 04:38:27 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 83A8D1065685 for ; Tue, 15 Jul 2008 04:38:27 +0000 (UTC) (envelope-from tapan.list@gmail.com) Received: from mu-out-0910.google.com (mu-out-0910.google.com [209.85.134.190]) by mx1.freebsd.org (Postfix) with ESMTP id 003478FC17 for ; Tue, 15 Jul 2008 04:38:26 +0000 (UTC) (envelope-from tapan.list@gmail.com) Received: by mu-out-0910.google.com with SMTP id i2so1951922mue.3 for ; Mon, 14 Jul 2008 21:38:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:in-reply-to:mime-version:content-type:references; bh=DnqxKmdFklFKbA00YkUPshn7fdTc0nQILkt7Fec4LLE=; b=TiZUjXy7WXaqe+QNHkg79FNM2O1GGXyHak30U15ifqOKXN+F3CKhzltpVq3SOVEWPb VubGk3GHD+Qn4KIRyTHCoNTsVwF9RhlP0YPsUS4fa3SofOIQ38eoxvWaILTEmbNbc6pV t4iCKXXhSkq2Rn1ARpBmSzq+EX50zd1domocg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:in-reply-to:mime-version :content-type:references; b=KXfHmgR224jia1Ba6RH+me7Yk3lo/Kp4XGRzX8bWuak7mjAer+LBqz7chh8OMBclko UKSH9CNrL8QL28yKTmz4BJbXCcEV1WXhumQBjjmX0H5HcbHQZk3ftXws6TcULJyRjpvU SBeeHRt42twYigqrpKrobET7K/WR4I6sNXxyA= Received: by 10.103.250.9 with SMTP id c9mr8507089mus.37.1216096705365; Mon, 14 Jul 2008 21:38:25 -0700 (PDT) Received: by 10.103.227.19 with HTTP; Mon, 14 Jul 2008 21:38:25 -0700 (PDT) Message-ID: <482257ad0807142138j1f7b7dd8nda7de865a4616fc0@mail.gmail.com> Date: Tue, 15 Jul 2008 10:08:25 +0530 From: "Tapan Chaudhari" To: freebsd-hackers@freebsd.org In-Reply-To: <200807151302.30415.doconnor@gsoft.com.au> MIME-Version: 1.0 References: <482257ad0807141106m679ec19frd853339637d27a2d@mail.gmail.com> <20080714165747.6c12371b@bhuda.mired.org> <482257ad0807141925m37c5b46bqa65c33852078b6f8@mail.gmail.com> <200807151302.30415.doconnor@gsoft.com.au> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Re: Can I change the device of the "/" mount point at boot time. X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Jul 2008 04:38:27 -0000 Hey, Thanks Deniel for the reply. I am aware of the fact you mentioned and will keep in mind. Well what i am trying to achieve is a simple thing to write an interception driver to catch all the i/os going to a particular device, do some manipulations on it and than let it through to the original device. Well as you mentioned about geom, I have recently posted a mail on GEOM mailing list as I could not find geom doing interception, the discussion is still on (You can see the mails with subject line "Can GEOM be used to intercept the I/o calls to an existing mounted device?"). Any sugessuions on interception driver will be helpful? As an interception driver is not possible, for time being I am going towards the redirection concept which will require a reboot and changing the devices on the mount points. For redirection driver, I dont think I will need geom. I can directly create a new device. Rather I think it would be an overhead using geom for a virtual device. Any thoughts on both the issues? Thanks, --Tapan. On Tue, Jul 15, 2008 at 9:02 AM, Daniel O'Connor wrote: > On Tue, 15 Jul 2008, Tapan Chaudhari wrote: > > Thank You Mateusz and Mike. I guess I am clear with my doubt now. I > > will also go through the man pages to go into depth of it. > > The critical thing is that the loader must read the kernel (and modules, > config etc..) from a disk the BIOS knows about. > > After that you can use any device the kernel knows about. > > As for the virtual device aspect - could you use a geom class to do you > want? It's hard to say without an overview of what you actually want to > achieve :) > > -- > Daniel O'Connor software and network engineer > for Genesis Software - http://www.gsoft.com.au > "The nice thing about standards is that there > are so many of them to choose from." > -- Andrew Tanenbaum > GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C >