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.