Date: Tue, 15 Dec 1998 20:45:50 -0800 From: Julian Elischer <julian@whistle.com> To: mjacob@feral.com Cc: freebsd-current@FreeBSD.ORG Subject: Re: Tape Driver Changes Proposed: Variable Mode as default Message-ID: <36773AFE.4487EB71@whistle.com> References: <Pine.LNX.4.04.9812151916440.8814-100000@feral-gw>
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Matthew Jacob wrote: > > I'm still processing and munching on the responses from the last call on > this- but closure is pretty close- in the interim, here's one that should > be less controversial: > > + forcing variable mode for tape devices unless quirked otherwise > > Do people have an opinion on this? In my original tape driver the default was not fixed, but rather, depended on a heuristic.. Most formats (e.g. QIC) in those days used a fixed mode, though variable mode was becoming more common. (as it had been originally in the 1/2 inch days) If you look in st.c (in 2.2) you should still see the heuristic code that decides which is the most likely default to use. Certainly it depended on the reported format of the drive. Ultimatly if there is a quirk for the drive you allow that to over-ride the default and a user can over-ride the quirk. You should ask the drive immediatly when asked to set a density, and return an error if the drive is not co-operative. I selected 4 sub devices for the tape driver to allow 4 easily available preselected modes and formats. I found this a great thing when presented with a drive that could do several formats or densities. I just used different subdevices to write the density I required. I presume you have looked at st.c in the old scsi system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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