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Date:      Wed, 7 Jul 1999 10:16:13 -0600 (MDT)
From:      "Kenneth D. Merry" <ken@plutotech.com>
To:        ohashi@mickey.ai.kyutech.ac.jp (Takeshi OHASHI)
Cc:        garbanzo@hooked.net, dmiller@search.sparks.net, akiyama@kme.mei.co.jp, freebsd-hackers@FreeBSD.ORG
Subject:   Re: DVD-ram
Message-ID:  <199907071616.KAA91832@panzer.kdm.org>
In-Reply-To: <199907071558.AAA02586@atohasi.mickey.ai.kyutech.ac.jp> from Takeshi OHASHI at "Jul 8, 1999 00:58:47 am"

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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


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