Re: [PATCH][SCS] sd: Read Capacity if (16) fails

Douglas Gilbert <dougg@xxxxxxxxxx> · Wed, 06 Aug 2008 18:44:15 +0200

Hugh Dickins wrote:

On Wed, 6 Aug 2008, Martin K. Petersen wrote:

"Hugh" == Hugh Dickins <hugh@xxxxxxxxxxx> writes:

Hugh> Commit e0597d70012c82e16ee152270a55d89d8bf66693 (sd: Identify
Hugh> DIF protection type and application tag ownership) says that if
Hugh> a disk is formatted with Inquiry bit PROTECT=1, it is required
Hugh> to support Read Capacity(16).  But my SD cards, accessed by
Hugh> builtin cardreader and generic USB storage, disagree.

Argh.  That's really broken.  USB storage has no business setting
PROTECT.

Can you send me the sg_inq output so I can see what else they are
returning?

sg_inq?  I assume that's the same as the inquiry_len bytes at inquiry:

00000000: 00 8d 00 01 1f 01 00 00 47 65 6e 65 72 69 63 2d  ........Generic-

00000010: 4d 75 6c 74 69 2d 43 61 72 64 20 20 20 20 20 20  Multi-Card      

00000020: 31 2e 30 30                                      1.00

Ah, sg_inq is a command which spells that out, here you go:

standard INQUIRY:
  PQual=0  Device_type=0  RMB=1  version=0x00  [no conformance claimed]
  [AERC=0]  [TrmTsk=0]  NormACA=0  HiSUP=0  Resp_data_format=1
  SCCS=0  ACC=0  TGPS=0  3PC=0  Protect=1  BQue=0
  EncServ=0  MultiP=0  [MChngr=0]  [ACKREQQ=0]  Addr16=0
  [RelAdr=0]  WBus16=0  Sync=0  Linked=0  [TranDis=0]  CmdQue=0
    length=36 (0x24)   Peripheral device type: disk
 Vendor identification: Generic-

 Product identification: Multi-Card      

 Product revision level: 1.00

Classic, USB strikes again! One needs to go back to SCSI-1
(1985 ?) to find when byte 5 bit 0 of an INQUIRY response
could be used for anything other than PROTECT.
So that bit is reserved in SCSI-2, SPC and SPC-2 then
has its current meaning in SPC-3 and SPC-4.

Doug Gilbert

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