SAS 2 - bit ordering for SNW-3 settings
Tim_Symons at pmc-sierra.com
Thu Mar 22 16:59:22 PDT 2007
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The examples in SAS2r08 Table 85, Table 86 and Table 87 each indicate that
the bit ordering in Table 84 is: Bit 0 (MSB), Bit 31 (LSB).
The example given in table 87 (row 5) expands out like this:
C9FC0001h : 1100 1001 1111 1100 0000 0000 0000 0001
MSB 1: START bit T
1: Tx SSC Centre spread
1001 : REQUESTED LOGICAL LINK RATE : 9h (3Gbps)
1: G1 without SSC supported
1: G2 without SSC supported
1: G3 without SSC supported
1: G1 with SSC supported
1: G2 with SSC supported
1: G2 with SSC supported
LSB 1: PARITY bit
I hope this clarifies the ordering.
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E-mail Tim_Symons at pmc-sierra.com
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Sheffield,
Sent: Thursday, March 22, 2007 10:17 AM
To: Day, Brian; T10 Reflector
Subject: RE: SAS 2 - bit ordering for SNW-3 settings
Intel has assumed the opposite.
Question - is the bit numbering in table-84 correct? In every other instance
where bits in a field are transmitted across the wire, the first bit
transmitted is the highest numbered bit in the field and is the highest
order. Why is the start bit numbered "0" and not "31"? I think there's a 100%
chance that breaking convention here will result in non-interoperable
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Day, Brian
Sent: Wednesday, March 21, 2007 1:39 PM
To: T10 Reflector
Subject: SAS 2 - bit ordering for SNW-3 settings
Any opinions to the contrary?
From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com]
Sent: Wednesday, March 21, 2007 12:10 PM
To: Day, Brian
Cc: Stephen FINCH; Tim Symons; Amr Wassal; Alvin.Cox at seagate.com
Subject: RE: bit ordering for SNW-3 settings
Based on the bit layout proposed in 07-091 for the SMP functions, I think bit
4 should be the MSB and bit 7 should be the LSB. That way, in the SMP
functions, it will have its natural encoding.
I suggest you post this Q&A to the T10 reflector to make sure nobody else has
assumed the opposite.
Rob Elliott, elliott at hp.com
Hewlett-Packard Industry Standard Server Storage Advanced Technology
From: Day, Brian [mailto:Brian.Day at lsi.com]
Sent: Wednesday, March 21, 2007 11:55 AM
To: Elliott, Robert (Server Storage)
Subject: bit ordering for SNW-3 settings
Can you clarify for me the bit ordering for the REQUESTED LOGICAL LINK RATE
in the SNW-3 settings?
The example uses "9", which is the same bit flipped or not.
Would be great to get a 1.5 example added to spec too since that would show
correct bit positions.
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