SMP frame - issue with maximum number of valid data bytes

Rich Deglin richd at serverengines.com
Thu Jan 24 17:32:03 PST 2008


Formatted message: <A HREF="r0801240_f.htm">HTML-formatted message</A>

SAS 2 (r13) section 9.4.3, I think, clearly shows that a maximum length SMP
RESPONSE frame consists of the following:
1 byte FRAME TYPE
1024 bytes RESPONSE BYTES
3 fill bytes
4 bytes CRC
In my reading of this section, this means that an SMP RESPONSE frame with a
maximum length RESPONSE BYTES field has NO MORE THAN 1025 valid data bytes
plus 3 fill bytes plus 4 CRC bytes = 1032 total bytes. The "header"
mentioned in section 10.4.3.2 is not shown here.
Section 10.4.3.2 conflicts with this. It states that a maximum length SMP
RESPONSE frame consists of the following:
1 byte FRAME TYPE
1 byte FUNCTION
1 byte FUNCTION RESULT
1 byte RESPONSE LENGTH
1024 bytes RESPONSE BYTES
0 fill bytes
4 bytes CRC
In my reading of this section, this means that an SMP RESPONSE frame with a
maximum length RESPONSE BYTES field has EXACTLY 1028 valid data bytes plus 0
fill bytes plus 4 CRC bytes = 1032 total bytes. A 4 byte "header" is
mentioned in the text of this section but is not explicitly defined, which I
would contend is an oversight in the document.
The SMP REQUEST frame descriptions demonstrate the same issue.
Please explain the apparent conflict. If there is a real problem here in the
spec, is a proposal necessary to correct it?
Also note that the same issues exist in the SAS 1.1 spec, but I am guessing
that no problems occurred in practice, due to the fact that the lengths of
the SAS 1.1 defined SMP REQUESTs and RESPONSEs do not get anywhere near the
limits.
_____________________________________________________________________________
______
This message, together with any attachment(s), contains confidential and
proprietary information of
ServerEngines LLC and is intended only for the designated recipient(s) named
above. Any unauthorized
review, printing, retention, copying, disclosure or distribution is strictly
prohibited.  If you are not the
intended recipient of this message, please immediately advise the sender by
reply email message and



More information about the T10 mailing list