From owner-freebsd-questions@FreeBSD.ORG Mon Feb 28 10:57:51 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DACA916A4CE for ; Mon, 28 Feb 2005 10:57:51 +0000 (GMT) Received: from obsecurity.dyndns.org (CPE0050040655c8-CM00111ae02aac.cpe.net.cable.rogers.com [69.199.47.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id 993F243D69 for ; Mon, 28 Feb 2005 10:57:51 +0000 (GMT) (envelope-from kris@obsecurity.org) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 018CC514AA; Mon, 28 Feb 2005 02:57:50 -0800 (PST) Date: Mon, 28 Feb 2005 02:57:50 -0800 From: Kris Kennaway To: Ted Mittelstaedt Message-ID: <20050228105750.GB15381@xor.obsecurity.org> References: <20050228022622.46627.qmail@web54003.mail.yahoo.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="1LKvkjL3sHcu1TtY" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i cc: Rob cc: FreeBSD questions Subject: Re: /dev/io , /dev/mem : only used by Xorg? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Feb 2005 10:57:52 -0000 --1LKvkjL3sHcu1TtY Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Feb 28, 2005 at 01:32:26AM -0800, Ted Mittelstaedt wrote: > Instead, they are part of the kernel itself. >=20 > All the /dev files are, /dev/random, /dev/ad0 and so on, are simple > files that take up only a few bytes of space. They are convenient > "hook points" to use to get to these devices. That is, when a program > accesses /dev/random, it isn't actually opening that file. Instead, > the kernel intercepts that call and supplies the program opening > that device with the output of the actual device. >=20 > This is why these device files are created with the mknod utility, > rather than just copying a file to /dev/random - since doing that is > accessing the device, not creating the device file. >=20 > So, deleting these /dev devices saves you practically no space at > all, and does not in fact delete the devices - it only deletes the > access point to them. The devices are still there in the kernel. No, in 5.x the device nodes are created automatically by devfs and only appear in /dev by default if support is enabled in the kernel. As the original poster discussed, /dev/io, /dev/mem and /dev/random are optional components of the 5.x kernel, although as I replied, the situations in which one would not want to include them are limited. Kris --1LKvkjL3sHcu1TtY Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (FreeBSD) iD8DBQFCIvkuWry0BWjoQKURAlGJAKDRi31AXSnR3mMvgpOuGrlLMiv0JgCgtbnp WYNg2HeD0k/FyVU1lkoBr6s= =DY0Q -----END PGP SIGNATURE----- --1LKvkjL3sHcu1TtY--