From owner-freebsd-geom@FreeBSD.ORG Sun Apr 23 15:56:09 2006 Return-Path: X-Original-To: freebsd-geom@FreeBSD.org Delivered-To: freebsd-geom@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D6D5E16A404 for ; Sun, 23 Apr 2006 15:56:09 +0000 (UTC) (envelope-from jylefort@FreeBSD.org) Received: from mirapoint2.brutele.be (mirapoint2.brutele.be [212.68.199.149]) by mx1.FreeBSD.org (Postfix) with ESMTP id 75A5B43D48 for ; Sun, 23 Apr 2006 15:56:08 +0000 (GMT) (envelope-from jylefort@FreeBSD.org) Received: from host-212-68-244-243.brutele.be (host-212-68-244-243.brutele.be [212.68.244.243]) by mirapoint2.brutele.be (MOS 3.7.3-GA) with ESMTP id DYR20308; Sun, 23 Apr 2006 17:56:06 +0200 (CEST) Received: from jsite.lefort.net (jsite.lefort.net [192.168.1.2]) by gateway.lefort.net (Postfix) with ESMTP id E3C985530; Sun, 23 Apr 2006 17:56:05 +0200 (CEST) Received: from jsite.lefort.net (localhost [127.0.0.1]) by jsite.lefort.net (Postfix) with SMTP id 8464FC0DA; Sun, 23 Apr 2006 17:56:05 +0200 (CEST) Date: Sun, 23 Apr 2006 17:56:05 +0200 From: Jean-Yves Lefort To: "Poul-Henning Kamp" Message-Id: <20060423175605.35a26523.jylefort@FreeBSD.org> In-Reply-To: <10365.1145803235@critter.freebsd.dk> References: <20060423153134.63716562.jylefort@FreeBSD.org> <10365.1145803235@critter.freebsd.dk> X-Mailer: Sylpheed running on FreeBSD Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg="PGP-SHA1"; boundary="Signature=_Sun__23_Apr_2006_17_56_05_+0200_HaDUqp6tUy.QZGft" X-Junkmail-Status: score=10/50, host=mirapoint2.brutele.be X-Junkmail-SD-Raw: score=unknown, refid=str=0001.0A090205.444BA20F.0015,ss=1,fgs=0, ip=212.68.244.243, so=2005-12-15 23:46:19, dmn=5.1.5/2006-02-08 Cc: freebsd-geom@FreeBSD.org Subject: Re: multiple of sector size I/O restriction X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 23 Apr 2006 15:56:09 -0000 --Signature=_Sun__23_Apr_2006_17_56_05_+0200_HaDUqp6tUy.QZGft Content-Type: text/plain; charset=US-ASCII Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, 23 Apr 2006 16:40:35 +0200 "Poul-Henning Kamp" wrote: > In message <20060423153134.63716562.jylefort@FreeBSD.org>, Jean-Yves Lefo= rt wri > tes: >=20 > >In sys/geom/geom_io.c, g_io_check() I find this: > > > > /* Reject I/O not on sector boundary */ > > if (bp->bio_offset % pp->sectorsize) > > return (EINVAL); > > > >Which causes this: > > > > # dd if=3D3D/dev/ad1 of=3D3Dtest bs=3D3D512 count=3D3D1 > > 1+0 records in > > 1+0 records out > > 512 bytes transferred in 1.889527 secs (271 bytes/sec) > > > > # dd if=3D3D/dev/ad1 of=3D3Dtest bs=3D3D513 count=3D3D1 > > dd: /dev/ad1: Invalid argument > > 0+0 records in > > 0+0 records out > > 0 bytes transferred in 0.000254 secs (0 bytes/sec) > > > >Why this restriction? >=20 > That is how disks work. I should reformulate my question. I've found some linux code which reads from a raw cd device in non-multiples of the sector size; I imagine that this code works on linux. This leads me to think that it is possible to overcome the hardware limitation by software means. Am I right? --=20 Jean-Yves Lefort jylefort@FreeBSD.org http://lefort.be.eu.org/ --Signature=_Sun__23_Apr_2006_17_56_05_+0200_HaDUqp6tUy.QZGft Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2.2 (FreeBSD) iD8DBQFES6OVyzD7UaO4AGoRAji4AJkBt/179r8wbcvcbT17slTCDJxr/QCeMz15 nWuzbp5beL9ndWEP5HjXCTs= =2QAv -----END PGP SIGNATURE----- --Signature=_Sun__23_Apr_2006_17_56_05_+0200_HaDUqp6tUy.QZGft--