[t13] SCSI ATA f/w revision bytes how many
p.lavarre at IEEE.org
Tue May 25 17:34:10 PDT 2004
* From the T10 Reflector (t10 at t10.org), posted by:
* Pat LaVarre <p.lavarre at ieee.org>
> "CDBs of arbitrary sizes up to a generous limit".
Yes. The FireWire CDB length limit of x3E8 = 1000 is the largest I've
seen anywhere in SCSI pass thru, almost 4X the common limit of xFF =
> the ORB_size field in the Unit_Characteristics entry
> in configuration ROM specifies a target's ORB size
> as a multiple of quadlets. Since it's an 8-bit field,
> ORBs are constrained to be less than
> or equal to 1020 bytes in length.
Ah, that fits.
x3FC = xFF * 4 = 1020 = 255 * 4 bytes. That leaves 1000 max for the
CDB once we lose the x14 = 20 = 5 * 4 bytes to the rest of the ORB that
is the wrapper around the CDB. We end with 1000 = x3E8 that looks like
a decimal limit, but is actually a hex limit i.e. x400 - x18.
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