sd_try_extended_inquiry for SPC-3 targets

Hello,

I am new to this forum, I tried to look up this question, but could not find any reference.

I have some trouble in with the 0xb1 VPD inquiry.
I set my device as a non-rotational device by returning 0x0001 in bytes 4-5 (MEDIUM ROTATION RATE) just as the SBC-3 demands:

"0001h Non-rotating medium (e.g., solid state)"

However, in the sysfs I see that the device is set as rotational device. I went into the kernel code to see why this happens. I found that the 0xb1 inquiry is only called if sd_try_extended_inquiry(sdp) returns a scsi version higher then SCSI_SPC_2. There is even a comment:
"
static int sd_try_extended_inquiry(struct scsi_device *sdp)

{
        /*
         * Although VPD inquiries can go to SCSI-2 type devices,
         * some USB ones crash on receiving them, and the pages
         * we currently ask for are for SPC-3 and beyond
         */
        if (sdp->scsi_level > SCSI_SPC_2)
                return 1;
        return 0;
}

"

my device supports SPC-3.
The scsi_level of my device (as I expose it in the page0 inquiry) is 0x5 according to SPC4 this means SPC-3.

This is from SPC4-revision 24 (3-6 are the same in revision 36e which is the latest I have):
"
00h The device does not claim conformance to any standard.
02h Obsolete
03h The device complies to ANSI INCITS 301-1997 (a withdrawn standard). 04h The device complies to ANSI INCITS 351-2001 (SPC-2).
05h The device complies to ANSI INCITS 408-2005 (SPC-3).
06h The device complies to this standard.
"

So it should pass the sd_try_extended_inquiry(spd).
The problem is that SCSI_SPC_2 is defined as 5 in include/scsi/scsi.h:484 (below). This causes SPC-3 devices not to be queried. and thus, they are set as rotational devices in the sysfs.

/*

 *  struct scsi_device::scsi_level values. For SCSI devices other than those
 *  prior to SCSI-2 (i.e. over 12 years old) this value is (resp[2] + 1)
 *  where "resp" is a byte array of the response to an INQUIRY. The

scsi_level
* variable is visible to the user via sysfs.
*/

#define SCSI_UNKNOWN    0
#define SCSI_1          1
#define SCSI_1_CCS      2
#define SCSI_2          3
#define SCSI_3          4        /* SPC */
#define SCSI_SPC_2      5
#define SCSI_SPC_3      6

If you read the comment it seams to me that the test (sdp->scsi_level > SCSI_SPC_2) is incorrect.
I looked at the native linux target, and it uses the scsi.h definitions, so it passes the test properly. For non native targets, this is a problem. Is this done by design (I can see that this code has been in the SCSI layer since the initial git)?

Thank you,
Ilan Steinberg

View this message in context: http://old.nabble.com/sd_try_extended_inquiry-for-SPC-3-targets-tp35421216p35421216.html
Sent from the linux-scsi mailing list archive at Nabble.com.

Ilan> If you read the comment it seams to me that the test Ilan> (sdp->scsi_level > SCSI_SPC_2) is incorrect.

scsi_device->scsi_level is not in sync with SPC-n. We set scsi_level to match the offset Linux constants at device discovery time.

Did you remember to include the Block Device Characteristics VPD page in your page 0?

Martin K. Petersen	Oracle Linux Engineering