Date: Mon, 19 May 1997 11:05:33 -0400 From: Charles Henrich <henrich@crh.cl.msu.edu> To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de> Cc: freebsd-scsi@FreeBSD.ORG Subject: Re: scsi library interface Message-ID: <19970519110533.07999@crh.cl.msu.edu> In-Reply-To: <19970519103618.LH45116@uriah.heep.sax.de>; from J Wunsch on Mon, May 19, 1997 at 10:36:18AM %2B0200 References: <19970518184034.10726@crh.cl.msu.edu> <19970519103618.LH45116@uriah.heep.sax.de>
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On the subject of Re: scsi library interface, J Wunsch stated:
> As Charles Henrich wrote:
>
> > Who wrote the scsi interface commands? (e.g. scsi_open, scsi_build
> > ..) I need to bang on them with some questions.
>
> Peter Dufault. He's also got a revamped library which he was asking
> people to test. It's on hub's anon ftp area, if i'm not mistaken.
Cool.
> > Also, in general when do you use raw mode devices vs. block mode vs
> > the .ctl devices?
>
> Buffered (`block') devices: to mount a filesystem over them. Nothing
> else. (Well, swapon(8) is in the same boat.)
>
> Raw (`character') devices: any other regular (i.e. read(2)/write(2))
> IO.
>
> Control devices: raw SCSI commands. State of the device doesn't
> matter then, e.g. you can open a control device for an unformatted
> disk, but you can't open the raw or buffered device.
Then why is it when you start sending raw SCSI read commands to rcd0.ctl
behind which lives a Toshiba, you explode the SCSI bus, yet if you send them
to /dev/cd0c things appear to work? (And with a plextor, both work!) Im
confused..
-Crh
Charles Henrich Michigan State University henrich@msu.edu
http://pilot.msu.edu/~henrich
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