[t13] Fwd: why not H = C = D ModeSense6 for just the header

Thomas Colligan tcolligan at apple.com
Wed Feb 12 11:41:21 PST 2003


This message is from the T13 list server.


Jim;

I see the same thing while doing firmware updaters for optical drives. Some
drives use 10 bytes and other use 12 bytes. There are a number of issues
forcing this direction.

Tom Colligan

> From: "Eschmann, Michael K" <michael.k.eschmann at intel.com>
> Date: Wed, 12 Feb 2003 10:52:36 -0800
> To: forum at t13.org, t10 at t10.org
> Subject: RE: [t13] Fwd: why not H = C = D ModeSense6 for just the header
> 
> This message is from the T13 list server.
> 
> 
> Hi Jim,
> 
> I'll leave the tape domain to you, but I've seen many CD-ROM's fail on the
> 6-byte format.  It may not fail on all, which may be why you see them working
> fine.
> 
> 6-byte mode sense:
>   struct _MODE_SENSE {
>       UCHAR OperationCode;
>       UCHAR Reserved1 : 3;
>       UCHAR Dbd : 1;
>       UCHAR Reserved2 : 1;
>       UCHAR LogicalUnitNumber : 3;
>       UCHAR PageCode : 6;
>       UCHAR Pc : 2;
>       UCHAR Reserved3;
>       UCHAR AllocationLength;
>       UCHAR Control;
>   } MODE_SENSE, *PMODE_SENSE;
> 
> 10-byte mode sense:
>   struct _MODE_SENSE10 {
>       UCHAR OperationCode;
>       UCHAR Reserved1 : 3;
>       UCHAR Dbd : 1;
>       UCHAR Reserved2 : 1;
>       UCHAR LogicalUnitNumber : 3;
>       UCHAR PageCode : 6;
>       UCHAR Pc : 2;
>       UCHAR Reserved3[4];
>       UCHAR AllocationLength[2];
>       UCHAR Control;
>   } MODE_SENSE10, *PMODE_SENSE10;
> 
> You'll see that the allocation length (or Parameter List Length)data doesn't
> line up, so good drivers will convert from 6-to-10 and pad the CDB out (with
> zeros) to a 12 or 16 byte CDB so bad drives (many, I suppose) will function.
> 
> 
> 
> -----Original Message-----
> From: James.C.Hatfield at seagate.com [mailto:James.C.Hatfield at seagate.com]
> Sent: Tuesday, February 11, 2003 3:32 PM
> Cc: forum at t13.org; t10 at t10.org
> Subject: RE: [t13] Fwd: why not H = C = D ModeSense6 for just the header
> 
> 
> This message is from the T13 list server.
> 
> 
> 
> Most ATAPI tape drives understand the 6-byte CDB.
> Some support the 10-byte format, as well.
> 
> ATAPI CD-ROM  drives support 6- and 10-byte forms.
> 
> The act of supporting the 10-byte CDB implies to <some> drivers that the
> device
> is a CD-ROM type of device.... leading to the driver getting confused.
> 
> Halve Phun !!!
> -----------------------------------------------------------------
> Jim Hatfield
> ATA Interface Firmware & T13 (ATA/ATAPI) Standards Representative
> Seagate Technology - PSG
>  e-mail:  James.C.Hatfield at seagate.com
>  s-mail:  389 Disc Drive;  Longmont, CO 80501 USA
>  voice:   720-684-2120
>  fax    :    720-684-2711
> ====================================================
> 
> 
>                  
>                   "Eschmann, Michael
>                   K"                          To:     <t10 at t10.org>,
> <forum at t13.org>  
>                   <michael.k.eschmann@        cc:
>                   intel.com>                  Subject:     RE: [t13] Fwd: why
> not H = C = D ModeSense6 for just the header
>                   Sent by:
>                   owner-forum at t13.org
>                   No Phone Info
>                   Available
>                  
>                   02/11/2003 04:19 PM
>                  
>                  
> 
> 
> 
> 
> This message is from the T13 list server.
> 
> 
> FYI, this is an issue with the Microsoft driver (supplied with their
> Windows 2000 OS) is not converting the SCSI 6-byte CDB to the 10-byte CDB
> format.  ATAPI drives don't understand the 6-byte format of "Mode Sense"
> (am I wrong?), so I believe this issue that MS reported has nothing to do
> with odd "byte" issues that you've been, er, peddling.  MKE.
> 
> 
> 
> -----Original Message-----
> From: Pat LaVarre [mailto:LAVARRE at iomega.com]
> Sent: Monday, February 10, 2003 8:22 AM
> To: t10 at t10.org; forum at t13.org
> Subject: [t13] Fwd: why not H = C = D ModeSense6 for just the header
> 
> 
> This message is from the T13 list server.
> 
> 
> Newsgroups: microsoft.public.vc
> Date: 2003-02-07 13:39:51 PST
> ...
> http://support.microsoft.com/default.aspx?scid=kb;en-us;Q813908
> SCSI Pass-Through Mode Sense Command May Crash the Computer
> ...
> If a SCSI Mode Sense command (operation code 0x1A) is
> sent by using SCSI pass-through to an ATAPI CD-ROM
> device, you may receive a "Stop" error message on a
> blue screen and the computer may then stop responding
> or may restart.  This may occur if the value of the
> Data Length field in the Mode Sense command is less
> than 8.  Note that this problem occurs only with the
> 6-byte Mode Sense command (operation code 0x1A), not
> with the 10-byte Mode Sense command (operation code
> 0x5A).
> ...
> 
> 




More information about the T10 mailing list