From owner-freebsd-hackers Wed Jul 7 9:17:37 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from panzer.kdm.org (panzer.kdm.org [216.160.178.169]) by hub.freebsd.org (Postfix) with ESMTP id 9A46315063 for ; Wed, 7 Jul 1999 09:17:28 -0700 (PDT) (envelope-from ken@panzer.kdm.org) Received: (from ken@localhost) by panzer.kdm.org (8.9.3/8.9.1) id KAA91832; Wed, 7 Jul 1999 10:16:13 -0600 (MDT) (envelope-from ken) Message-Id: <199907071616.KAA91832@panzer.kdm.org> Subject: Re: DVD-ram In-Reply-To: <199907071558.AAA02586@atohasi.mickey.ai.kyutech.ac.jp> from Takeshi OHASHI at "Jul 8, 1999 00:58:47 am" To: ohashi@mickey.ai.kyutech.ac.jp (Takeshi OHASHI) Date: Wed, 7 Jul 1999 10:16:13 -0600 (MDT) Cc: garbanzo@hooked.net, dmiller@search.sparks.net, akiyama@kme.mei.co.jp, freebsd-hackers@FreeBSD.ORG From: "Kenneth D. Merry" X-Mailer: ELM [version 2.4ME+ PL54 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Takeshi OHASHI wrote... > ken>>> I am a beta tester of the new od driver. It almost works fine on some > ken>>> beta testers system, but we cannot redistribute without Mr. Akiyama's > ken>>> permit. > ken>> > ken>>Of course. Well, if he doesn't mind, I'd like to take a look at it at some > ken>>point. > > He is preparing the review version of od-driver. Please wait some days. Cool. > ken>>> I have a new question. If od driver is needless, why cd and da drivers > ken>>> are sepalate yet? Only difference is TOC ioctls, isn't it? > > ken>>It's true that the read/write interfaces of the two drivers are very > ken>>similar, but there are a number of other differences. They probably could > ken>>be combined with some difficulty, but then there are booting concerns (if > ken>>everything is a DA device, how can you make sure you aren't booting off a > ken>>CDROM drive?), major numbers, and device names to think about as well. > > Thank you for your answer. > > I think this situation is like as OD devices. Some DVD-RAM/MO/PD > drives are recognized as DA and others are CD. For example, A PD media > is used as a DA on PD drives. The PD media is used as a CD on DVD-RAM > and DVD-ROM drives. It is very confusing. Sometime we want to disable > booting from these devices. It's a similar situation, but not the same. It's fairly difficult to boot off a CDROM drive, since the media is read-only. I've done it before, but it certainly isn't the usual case. A medium capable of read/write, however, could more easily be used for booting. The bottom line is, we want to avoid duplicating code if we can help it. If there is a good reason to have a separate OD driver, it can certainly be done. If it's only done so that PD drives have a different device name, I don't think that's enough to justify it. Ken -- Kenneth Merry ken@plutotech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message