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Date:      Fri, 15 Mar 2002 19:02:26 -0700
From:      Scott Long <scott_long@btc.adaptec.com>
To:        Chris Dillon <cdillon@wolves.k12.mo.us>
Cc:        freebsd-scsi@freebsd.org, freebsd-fs@freebsd.org
Subject:   Re: CD-MRW a.k.a Mt. Rainier support
Message-ID:  <20020316020226.GA12097@bunsenhoneydew.btc.adaptec.com>
In-Reply-To: <Pine.BSF.4.32.0203131116220.31162-100000@mail.wolves.k12.mo.us>
References:  <Pine.BSF.4.32.0203131116220.31162-100000@mail.wolves.k12.mo.us>

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On Wed, Mar 13, 2002 at 11:59:06AM -0600, Chris Dillon wrote:
> 
> CC'd to freebsd-fs since this is somewhat fs-related...
> 
> Is anyone working on implementing support for CD-MRW (apparently
> included in MMC-3) into either the SCSI cd driver or the ATAPI cd
> driver?  Where/how would be the best place to implement this so that
> it will work with either ATAPI or SCSI drives?  Would implementing it
> in the SCSI cd driver be best, since we now have the option of using
> ATAPI drives with CAM?
> 
> In case anyone is wondering what CD-MRW (Mt. Rainier Re-Writable) is,
> it is a new standard (currently only available in the Yamaha CRW3200
> series, that I know of), that allows on-the-fly transparent
> formatting, hardware defect management, and 2K-block logical
> addressing of CD-RW discs and specifies a specialized UDF filesystem
> to be used along with these hardware abilities.  This will make drives
> supporting this standard act like a more traditional magnetic-media
> removable drive, thus greatly simplifying reading/writing to CD-RW
> discs.  Since MRW uses a new format it is not backwards compatible
> with any existing CD-RW formats, though it is possible to _read_ a MRW
> formatted disc in a regular drive with the proper software support.
> MRW uses UDF as its standard filesystem, which we do not yet support,
> though I envision using the hardware MRW support of the drive to put
> just about anything you want onto it, including FAT or UFS, to use it
> as a "regular" drive.
> 
> I'd love to take a shot at implementing this if someone isn't already,
> though I'll need to find the specs for the hardware side of Mt.
> Rainier.  Apprently it is implemented in the new MMC-3 command set.
> Anyone have any pointers?

This drive sounds very interesting.  Unfortunaley, until the standard
becomes ubiquitous, any UDF implementation will still need to understand
read-modify-write and sparing tables.  UDF is the natural format for it
since with removable media you want inter-changability with other
systems, but there should be nothing stopping you from putting UFS on
it too.
I've already started a UDF implementation for FreeBSD.  Patches for
5.0-CURRENT can be found at http://people.freebsd.org/~scottl, along
with a link for slightly older -STABLE patches.  The current status
is that CD-RWs and DVD-ROMs can be read (though Sparing Tables are
still missing for CD-RW), and once I've cleaned up and filled in the
code some more, I intend for it to go into 5.0-RELEASE.  I'd welcome
any help on the project, escpecially if someone wants to tackle the
writing support.

Scott

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