Date: Tue, 5 Sep 1995 20:33:54 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, vak@cronyx.ru Cc: hackers@freebsd.org Subject: Re: Help installing IDE CD-ROM driver Message-ID: <199509051033.UAA02568@godzilla.zeta.org.au>
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>> >There is no disklabel support in wcd driver, that's why >> >there is no /dev/wcd0a device. Is it really needed? >> >> Not really, but it simplifies the device naming scheme and all other >> cdrom drivers support it. >All CD-ROM drivers support partition A. Some of them >also support partition C, which is the same. wcd actually sort of supports 2^30 partitions, all the same (because wcdopen() doesn't check the top 30 bits in the device number :-(). There would be aliasing problems if someone created one of the other minors and used both. There are aliasing problems now between the cdev and the bdev. E.g., opening the cdev while the bdev is open invalidates the F_OPEN flag and messes up media change stuff. The `fmt' arg to wdopen() and wdclose() that is required to distinguish cdevs from bdevs is missing. dsopen() and dsclose() handle all these aliasing problems. >What about ln -s /dev/wcd0c /dev/wcd0a? :-) It should be wcd0 since there are no partitions. The slice naming scheme has this as a special (xxd0 is actually minor 2 on slice 1). Bruce
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