[t10] SPC of MMC obsolete or different

keiji_katata at post.pioneer.co.jp keiji_katata at post.pioneer.co.jp
Thu Jan 9 18:40:45 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* keiji_katata at post.pioneer.co.jp
*

Hi Pat,

SFF INF-8090 describes DBD shall be set to 1. This means host software
shall not use block descriptor. Obsoleted SFF-8020 had wrong description.
But it has been gone.
For MMC device, Mode Sense 10, Mode Select 10 is mandatory by the MMC. By
the SPC, Mode Sense 6, Mode Select 6 is mandatory for all devices. I think
it could be allowed.

By the old story of the very famous ATA/ATAPI device driver bug, CD-ROM
devices could not support Mode Sense 6, Mode Select 6. It seems that this
manner of MMC device is continued still now. This is the big problem of MMC
devices that PC manufactures always request FW change to escape from bug of
OS or device driver. Then devices can not support specifications in ANSI
documents. PC manufactures said "the problem is fixed by FW change" always.
Because OS and device driver are not repairable. Furthermore, device
manufactures can not discuss bugs of OS or device driver between
manufactures. Because it is covered by NDA. (nice!)

Best regards,

Keiji Katata
PIONEER CORP.







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subject:    [t10] SPC of MMC obsolete or different


* From the T10 Reflector (t10 at t10.org), posted by:
* "Pat LaVarre" <LAVARRE at iomega.com>
*
> From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com]
> I notice that mmc4r01f includes sections defining
> commands that have a home in other standards
> (especially SPC-3 ...

Me, offline, I heard that the SPC in MMC is not merely obsolete, but
substantively different in small details, when compared with the ANSI idea
of SPC.

Untrue?

If true, this would be a pernicious binary incompatibility analogous to the
SFF idea of ModeSense, in which DBD zeroed meant no block descriptor, in
contrast with the ANSI idea of ModeSense, in which DBD zeroed meant yes
block descriptor.  Also analogous to SFF making ModeSense10 required, while
leaving ModeSense6 unmentioned, in contrast with ANSI requiring ModeSense6,
but leaving ModeSense10 optional.

I've also heard rumours of an SPC vs. RBC conflict over ModeSense, dunno if
those are true either.

Curiously yours in essentially irredeemable ignorance, Pat LaVarre

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