So there's really nothing to worry anymore :)

Thanks.

stefano


On Friday 28 November 2003 16:47, you wrote:
> On Fri, 28 Nov 2003, Stefano Barbato wrote:
> > > That's not an error.  36 bytes is the normal length of an INQUIRY
> > > response.  I'm not quite sure why the driver asks for 255 bytes; under
> > > 2.6 it only asks for 36.  The FIX_INQUIRY flag isn't needed.
> >
> > INQUIRY len seems to be (errouneously?) hardcoded into scsi layer:
> >
> > 2.4.22 [scsi_scan.c:589]
> > ---------
> > scsi_cmd[0] = INQUIRY;
> >  [.....]
> > scsi_cmd[4] = 255;
> > ---------
> >
> > 2.6 [scsi_scan.c:333]
> > ---------
> > scsi_cmd[0] = INQUIRY;
> > scsi_cmd[4] = 36;       /* issue conservative alloc_length */
> > ---------
>
> That's not an error either.  An INQUIRY command is allowed to use a very
> big buffer.  If the device doesn't have that much data, it only sends what
> it has.
>
> > So the problem is this other reader that successfully (but not correctly
> > if the INQ is only 36 bytes long!) transfer all 255 bytes:
> > =============================
> > Nov 26 17:16:06 epia kernel: usb-storage: *** thread awakened.
> > Nov 26 17:16:06 epia kernel: usb-storage: Command INQUIRY (6 bytes)
> > Nov 26 17:16:06 epia kernel: usb-storage: 12 00 00 00 ff 00 1b c0 84 67
> > 5e c5 Nov 26 17:16:06 epia kernel: usb-storage: Bulk command S 0x43425355
> > T 0x1 Trg 0 LUN 0 L 255 F 128 CL 6
> > Nov 26 17:16:06 epia kernel: usb-storage: Bulk command transfer result=0
> > Nov 26 17:16:06 epia kernel: usb-storage: usb_stor_transfer_partial():
> > xfer 255 bytes
> > Nov 26 17:16:06 epia kernel: usb-storage: usb_stor_bulk_msg() returned 0
> > xferred 255/255
> > Nov 26 17:16:06 epia kernel: usb-storage: usb_stor_transfer_partial():
> > transfer complete
> > Nov 26 17:16:06 epia kernel: usb-storage: Bulk data transfer result 0x0
> > Nov 26 17:16:06 epia kernel: usb-storage: Attempting to get CSW...
> > Nov 26 17:16:06 epia kernel: usb-storage: Bulk status result = 0
> > Nov 26 17:16:06 epia kernel: usb-storage: Bulk status Sig 0x53425355 T
> > 0x1 R 0 Stat 0x0
> > Nov 26 17:16:06 epia kernel: usb-storage: Fixing INQUIRY data to show
> > SCSI rev 2 - was 0
> > Nov 26 17:16:06 epia kernel: usb-storage: scsi cmd done, result=0x0
> > Nov 26 17:16:06 epia kernel: usb-storage: *** thread sleeping.
> >
> > =============================k
> >
> > stefano
>
> Even that isn't a problem.  The SCSI layer ignores everything after the
> first 36 bytes of the INQUIRY response.
>
> Alan Stern



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