Date: Fri, 24 Jan 2003 15:29:36 -0800 From: Marcel Moolenaar <marcel@xcllnt.net> To: phk@FreeBSD.ORG Cc: arch@FreeBSD.ORG Subject: Re: GEOM and CDROM media (was: CFR: Volume labels in FFS) Message-ID: <20030124232936.GB47190@dhcp01.pn.xcllnt.net> In-Reply-To: <4614.1043447912@critter.freebsd.dk> References: <20030124222718.GN53114@roark.gnf.org> <4614.1043447912@critter.freebsd.dk>
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On Fri, Jan 24, 2003 at 11:38:32PM +0100, phk@FreeBSD.ORG wrote: > In message <20030124222718.GN53114@roark.gnf.org>, Gordon Tetlow writes: > > >I can also forsee being able to hook into devd to do some automounting magic > >for things like zip disks and cdroms (obviously not with FFS, but cd9660 > >support would be a good thing to have once GEOM recognizes cdroms). > > I am currently experimenting with code for removable devices which > will poll the drive if there is a media in it (too many drives/interfaces > are too stupid to tell us) and this can and could be include CDROMS > as well. > > The question in my mind is how to handle complex CDROM formats: What about an intermediate layer that splits the physical media into logical media based on the format. Example given below (forgive me the unethical device naming -- it's for illustration purposes): > 1: Data track > 2: Data track > 3: Music "You can build a mainframe from the things you find at home" > 4: Music "I'm a mainframe baby" > 5: Data track > 6: Data track, multi-session with track 5. /dev/cd0/data/track1 /dev/cd0/data/track2 /dev/cd0/data/track3 /dev/cd0/data/track4, multi-session with track 3 /dev/cd0/audio/track1 /dev/cd0/audio/track2 The track numbers are logical so you can treat /dev/cd0/audio as a logical audio-only CD and /dev/cd0/data as a logical data-only CD. Whether you want to have GEOM deal with audio tracks or just present a logical audio CD depends on how loud you scream if someone would write GEOM_MP3 :-) You could treat the DVD VOBs in the same way I guess... I guess the point I'm getting at is that GEOM stacks objects to abstract the physical representation by presenting logical entities. An abstraction layer based on the format seems to fit in... Just some random thoughts... -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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