From owner-freebsd-hackers Wed Sep 23 17:59:33 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id RAA20415 for freebsd-hackers-outgoing; Wed, 23 Sep 1998 17:59:33 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from cain.gsoft.com.au (genesi.lnk.telstra.net [139.130.136.161]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id RAA20403 for ; Wed, 23 Sep 1998 17:59:22 -0700 (PDT) (envelope-from doconnor@gsoft.com.au) Received: from cain.gsoft.com.au (cain [203.38.152.97]) by cain.gsoft.com.au (8.8.8/8.6.9) with ESMTP id KAA18016; Thu, 24 Sep 1998 10:28:25 +0930 (CST) Message-ID: X-Mailer: XFMail 1.3 [p0] on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <199809231833.UAA07940@labinfo.iet.unipi.it> Date: Thu, 24 Sep 1998 10:28:24 +0930 (CST) From: "Daniel O'Connor" To: Luigi Rizzo Subject: Re: backport of atapi-cd to -STABLE Cc: hackers@FreeBSD.ORG, abial@nask.pl, oppermann@pipeline.ch, netmonger@genesis.ispace.com, (Mike Smith) Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > to clarify, the so-called jitter correction in "cdd" serves for those > drives whose firmware does not guarantee that the data you get from the > disk are for the block you requests and instead could give you data for > a nearby block (presumably, but this is just an assumption, from time > to time the firmware misses a block and passes you the next one). It happens because CDDA doesn't have block markers, so the firmware can't actually tell if it got the right block when it reads it.. It is essentially working on 'dead reckoning' to get the right block. Jitter correction checks the blocks to see if they 'line up' or not.. --------------------------------------------------------------------- |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 | --------------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message