[ovs-dev] [PATCH 1/3] odp-util: Refactor ovs_u128 handling functions.

[Jarno Rajahalme]

> On Jun 6, 2015, at 2:13 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> On Fri, May 29, 2015 at 03:09:05PM -0700, Joe Stringer wrote:
>> Thanks for review,
>> 
>> On 29 May 2015 at 13:22, Ben Pfaff <blp at nicira.com> wrote:
>>> On Mon, Apr 13, 2015 at 05:56:15PM -0700, Joe Stringer wrote:
>>>> Signed-off-by: Joe Stringer <joestringer at nicira.com>
>>> 
>>> The code in scan_u128() looks wrong to me: I don't see anything that
>>> makes the second call to ovs_scan(), to get the mask, skip past the
>>> value, e.g. by passing s + n to the second ovs_scan() or by advancing s
>>> with s += n.
>> 
>> You're right, I also used this for conn_label but I didn't attempt to
>> mask the connlabel. Also, mask doesn't make sense for UFID so it
>> wasn't tested there.
>> 
>>> I have another idea too: these issues for ovs_u128 are quite similar to
>>> the issues for UUIDs, which are also exactly 128 bits long and already
>>> have support for parsing, formatting, and so on, and furthermore have a
>>> distinctive format that is easily identifiable.  Have you considered
>>> using UUIDs as the representation for ufids?
>> 
>> I don't think I'd recognized that UUID was even present. I think it
>> makes sense to reuse the same for UUID and UFID.
>> 
>> My other aim was to make this usable by conn_label, which also implies
>> optional mask. Perhaps it's appropriate to morph this function into a
>> wrapper for the UUID parsing/formatting, with support for masks.
>> (Should *all* 128-bit values be printed like UUIDs, or just ID-like
>> information?)
> 
> Sorry about my delayed response.
> 
> Hmm.  I see a useful likeness between UUIDs and UFIDs, because they're
> both essentially random numbers (although a hash is somewhat different
> from a random UUID).  I don't know enough about conn_labels to know
> whether they're also the same kind of thing.  Do they contain structured
> data (e.g. extracted from a flow) or are they like UUIDs and UFIDs?  If
> conn_labels qualitatively different, then maybe they should not be
> formatted the same way.

Conn labels is a set of typically individual bits, meaning of which depends on the system/controller configuration.

  Jarno

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