Matt,
A 32-bit alignment constraint means
that TTL (Tag/Type/Length) can be 8 or 12 bytes, and Value a multiple of
4 bytes.
A 64-bit alignment constraint means
that TTL is 8 bytes (or even a multiple thereof), and Value a multiple
of 8 bytes.
Hence, the decisions on the TTL and
Value do not seem to be completely independent.
I'd suggest that:
1) we decide first which alignment to
follow first: 32-bit or 64-bit, and
2) we decide next the size of the TTL,
in accordance with the alignment, as explained above.
Regards,
-Robert
Matthew.Ball@Sun.COM wrote on 05/06/2009 11:29:47
PM:
> Hi Scott,
>
> I was trying to reduce permutations, but maybe it makes sense to
> have the following breakdown of independent decisions tomorrow:
>
> Shall the Tag/Type/Length fields occupy 8 bytes (as described in the
> 64-bit proposal) or 12 bytes (as described in the 32-bit proposal)?
> Shall the Value field be aligned to 4 byte or
8 byte boundaries?
>
> I suspect the preference may be to use 8 bytes for the Tag/Type/
> Length fields, and align the Value field to 4 byte boundaries --
> essentially a hybrid of the 32-bit and 64-bit proposals. Do
folks agree?
>
> Thanks!
> -Matt
>
> Scott Kipp wrote:
> Matt,
> Thanks for putting this together. It is
clearer when you have
> diagrams like this. It seems like we ought to reserve bits/octets
> if we aren't going to use them in a field. It's kind of odd
that
> the 32-bit proposal header takes up 3 words and the 64 bit proposal
> header takes up 2 words. The TTLV format should be a different
> discussion than the bit alignment. I prefer the TTLV format
of the
> 64 bit alignment proposal, but either will do.
> One thing your diagram doesn't show is that padding
in the 32-bit
> proposal is either 1 to 3 bytes while the padding in the 64 bit
> proposal is 1 to 7 bytes to get the alignment. Your examples
in the
> other proposals clearly show this.
> Thanks for clearing this up,
> Scott
>
> From: Matthew.Ball@Sun.COM [mailto:Matthew.Ball@Sun.COM]
> Sent: Wednesday, May 06, 2009 3:41 PM
> To: kmip@lists.oasis-open.org
> Subject: [kmip] Diagram showing difference between
32-bit and 64-bit
> binary alignment proposals
>
> Hi Folks,
>
> I've put together a diagram that shows the difference between the
> 32-bit and 64-bit proposals in graphic detail. For these types
of
> comparisons, words don't quite express the idea as well as pictures
do.
>
> As the poll showed, the group is about halfway split between 32-bit
> and 64-bit, and I'm hoping that this diagram will show that the 64-
> bit proposal works just as well for 32-bit applications.
:)
>
> With any luck we'll reach a conclusion via e-mail and will be able
> to have a quick vote in tomorrow's meeting to pick one of these
> proposals. I do prefer the 64-bit option as more useful, but
would
> be happy to approve the 32-bit version if that's the group's favorite.
>
> Let me know if you have any comments or questions!
>
> Cheers,
> -Matt
>
> [attachment "matthew_ball.vcf" deleted by Robert Haas/Zurich/IBM]
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