[garloff@suse.de: Re: [linux-usb-devel] Re: /proc/scsi/map]

From: Kurt Garloff (kurt@garloff.de)
Date: Sun Jun 16 2002 - 20:24:00 EST

Hi,

forgot to Cc: the other recipients.
I did not want to turn this into a private discussion.

----- Forwarded message from Kurt Garloff <garloff@suse.de> -----

Date: Mon, 17 Jun 2002 02:46:24 +0200
From: Kurt Garloff <garloff@suse.de>
To: James Bottomley <James.Bottomley@steeleye.com>
Subject: Re: [linux-usb-devel] Re: /proc/scsi/map
In-Reply-To: <200206162314.g5GNEYf03058@localhost.localdomain>
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Hi,

On Sun, Jun 16, 2002 at 06:14:33PM -0500, James Bottomley wrote:
> oliver@neukum.name said:
> > But the drivers already know, or would have to be taught to know about
> > it. Somewhence that information has to come. You cannot avoid that
> > effort.
>
> Not necessarily: consider the SCSI WWN, which is supported by most modern SCSI
> devices. The driver never probes for or asks for this. Nowhere in the
> current SCSI code do we ask for this. However user level commands (like
> sg_inq) can formulate the 0x83 page inquiry to get this and return the output.
> This works today with the current driver.

This may work for your disks. You just can't open the device node for a
tape, if there is no medium inserted. If you know the mapping between
to a sg device you can use it.
That's the second piece of information that /proc/scsi/map provides.

The first piece is that the kernel tells kernel tells you the way it is
attached by reporting CBTU, which is a good identifier for good old parallel
SCSI that most of our SCSI code still is assuming.

That will change one day ...

Regards, 

-- 
Kurt Garloff                   <kurt@garloff.de>         [Eindhoven, NL]
Physics: Plasma simulations    <K.Garloff@TUE.NL>     [TU Eindhoven, NL]
Linux: SCSI, Security          <garloff@suse.de>    [SuSE Nuernberg, DE]
 (See mail header or public key servers for PGP2 and GPG public keys.)

----- End forwarded message -----

-- 
Kurt Garloff                   <kurt@garloff.de>         [Eindhoven, NL]
Physics: Plasma simulations    <K.Garloff@TUE.NL>     [TU Eindhoven, NL]
Linux: SCSI, Security          <garloff@suse.de>    [SuSE Nuernberg, DE]
 (See mail header or public key servers for PGP2 and GPG public keys.)
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