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SubjectRe: SCSI /dev/sg question
On Wed, Aug 25, 1999 at 06:57:23AM -0700, gokhan sozmen wrote:
> Hi folks,
>
> I was asked this question today and could not come up
> with an answer:
>
> Does a SCSI host adapter itself get mapped to a
> /dev/sgx device file? For example if you have an
> adapter (ID=7)with one SCSI disk (ID=0), after a
> SCSI bus scan do you get:
>
> /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?

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