Re: SCSI /dev/sg question

Kurt Garloff (garloff@suse.de)
Sun, 29 Aug 1999 23:42:16 +0200


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On Wed, Aug 25, 1999 at 06:57:23AM -0700, gokhan sozmen wrote:
> Hi folks,
>=20
> I was asked this question today and could not come up
> with an answer:
>=20
> Does a SCSI host adapter itself get mapped to a
> /dev/sgx device file? For example if you have an
> adapter (ID=3D7)with one SCSI disk (ID=3D0), after a
> SCSI bus scan do you get:
>=20
> /dev/sga -> disk
> /dev/sgb -> adapter ??

This is not possible. The Linux SCSI drivers that I know don't allcoate an
entry in the list of SCSI devices, not in /proc/scsi/scsi, nor in /dev/sg?.

But what do you want to achieve by sending SCSI commands via sg to the
adapter?=20

The adapters don't support target mode by the way, so you can't communicate
between two SCSI adapters. I believe, Marc SCHAEFER is working on it.

> If not, how can you talk to an adapter driver if
> there are no SCSI devices are attached to it?

Normally, you don't want to tal to the adpater, but to devices attached to =
it.
This is just handled the normal way: Use one of the high level interfaces,
Linux provides: sd, sr, st, sg.

If you want to change SCSI adapter configuration, some adapters provide
kernel/module parameters. Some are even configurable dynamically via the
/proc interface.

> All responses appreciated.

Hope this helps.
--=20
Kurt Garloff <garloff@suse.de> Wuppertal, FRG
PGP2 key: See mail header, key servers Linux kernel development
SuSE GmbH, N=FCrnberg, FRG SCSI drivers: tmscsim(DC390), DC395

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