Date: Mon, 28 Feb 2005 02:57:50 -0800 From: Kris Kennaway <kris@obsecurity.org> To: Ted Mittelstaedt <tedm@toybox.placo.com> Cc: FreeBSD questions <freebsd-questions@freebsd.org> Subject: Re: /dev/io , /dev/mem : only used by Xorg? Message-ID: <20050228105750.GB15381@xor.obsecurity.org> In-Reply-To: <LOBBIFDAGNMAMLGJJCKNGEIOFAAA.tedm@toybox.placo.com> References: <20050228022622.46627.qmail@web54003.mail.yahoo.com> <LOBBIFDAGNMAMLGJJCKNGEIOFAAA.tedm@toybox.placo.com>
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--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--
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