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03h The device complies to ANSI INCITS 301-1997 (a withdrawn standard).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
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