From owner-freebsd-hackers Sun Oct 19 18:23:09 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id SAA15244 for hackers-outgoing; Sun, 19 Oct 1997 18:23:09 -0700 (PDT) (envelope-from owner-freebsd-hackers) Received: from dyson.iquest.net (dyson.iquest.net [198.70.144.127]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id SAA15236 for ; Sun, 19 Oct 1997 18:23:01 -0700 (PDT) (envelope-from toor@dyson.iquest.net) Received: (from root@localhost) by dyson.iquest.net (8.8.7/8.8.5) id UAA05647; Sun, 19 Oct 1997 20:21:26 -0500 (EST) From: "John S. Dyson" Message-Id: <199710200121.UAA05647@dyson.iquest.net> Subject: Re: nasty problem with vnode and other disk drivers? In-Reply-To: <19971020010910.4635.qmail@iq.org> from "proff@iq.org" at "Oct 20, 97 11:09:09 am" To: proff@iq.org Date: Sun, 19 Oct 1997 20:21:26 -0500 (EST) Cc: freebsd-hackers@FreeBSD.ORG Reply-To: dyson@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL31 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk proff@iq.org said: > > > > > It isn't expected behavior, but raw, block devices currently need I/O on > > 512 byte boundarys for integrals of 512 byte lengths. > > > > John > > > > > > > > /dev/rvn0 is a character device. /dev/vn0 is the block device. > I understand, as I said (raw, block device) is a type of character device. So is a tty. Try seeking on a tty -- it won't skip characters, but it is possible to implement. Such (raw, block device) types usually support aligned transfers only (even on some SVR4 derivatives.) If you want to do unaligned transfers, it is best to do some buffering. There might be something coming along in the future, but not now. -- John dyson@freebsd.org jdyson@nc.com