On Thu, 7 Feb 2002, Matthew Dharm wrote:
> If you need 56 bytes for SCSI-4, then why not get 36 bytes, see if the
> device is SCSI 4, then ask for the 56 bytes if it is.
Nobody disagreed with this proposal.
> Look, this issue is going to continue to haunt us as more and more
> "emulated SCSI" devices and busses appear. And, no version of windows will
> make an initial INQUIRY request for more than 36 bytes. Ever. Which means
> that more and more devices will behave that way.
>
> Doesn't the SCSI-II spec call for doing things this way, anyway?
Not at all. Only 36 bytes were _required_ to be returned and bytes 56 to
95 was reserved for future use but could be returned. They just weren't
allowed to contain relevant information. Even SCSI-1 didn't limit INQUIRY
data to 36 bytes (5 bytes followed by vendor unique).
> Ask for
> 36, determine how much is available, and then ask for it all? I know they
> call out that procedure explicitly for mode pages...
> Gerard (I hope that's an acceptable way to spell your name, given that I
> don't know how to type the character after the 'G'), I just don't quite
> understand your objection here... my concern was that I've been told that
> some low-level drivers snoop the data (for some unknown reason), but that's
> really my only concern.
The sym drivers snoops the INQUIRY under Linux SCSI but does not under
FreeBSD CAM. If Linux SCSI gets ever up-to-date about the device
characteristics got from INQUIRY available to low-level drivers, the snoop
will obviously go away.
Gérard.
> Matt
>
> On Wed, Feb 06, 2002 at 11:07:48PM +0100, Gérard Roudier wrote:
> >
> >
> > On Thu, 7 Feb 2002, Alan Cox wrote:
> >
> > > > A SCSI device that is broken for INQUIRY is definitely broken for SCSI.
> > > > FYI, we need at least 56 bytes of INQUIRY data to be possible for SPC2
> > > > (SCSI 4).
> > >
> > > Possible, but not required for the initial INQUIRY
> >
> > The Linux SCSI layer performs a single INQUIRY for the device discovery
> > process. It was proposed to shorten this INQUIRY to 36 bytes.
> >
> > For now, all SCSI access methods I have ever seen perform a single
> > INQUIRY for this scan.
> >
> > Gérard.
> >
> > PS:
> > Btw, if what you want to say does not fit in your usual 2 lines of text,
> > then you should take time to elaborate or just not to post or post later
> > when you will have time enough.
>
> --
> Matthew Dharm Home: [EMAIL PROTECTED]
> Maintainer, Linux USB Mass Storage Driver
>
> My mother not mind to die for stoppink Windows NT! She is rememberink
> Stalin!
> -- Pitr
> User Friendly, 9/6/1998
>
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