[ovs-dev] [PATCH 3/3] [RFC] Add oxm_mf_fields

[Simon Horman]

On Mon, Apr 23, 2012 at 08:34:45AM +0900, Simon Horman wrote:
> On Fri, Apr 20, 2012 at 08:36:57AM -0700, Ben Pfaff wrote:
> > On Fri, Apr 20, 2012 at 09:24:05AM +0900, Simon Horman wrote:
> > > This may be used in a similar way to nxm_mf_fields
> > > to handle parsing and serialisation of OXM TLVs.
> > > 
> > > Signed-off-by: Simon Horman <horms at verge.net.au>
> > 
> > My own thought for how to do OXM was to just add a new 'oxm_header'
> > member (and possibly 'oxm_name') to struct mf_field.  Do you really
> > think we need a whole new mostly redundant array?  I hope not.
> 
> Hi Ben,
> 
> I hadn't thought about that, but it does seem like a reasonable approach.
> I'll see about implementing it.

One problem that I see arising here is that some fields are maskable in OXM
but not in NXM and vice versa. When reading the spec I made the following
notes.

+ OXM_OF_ETH_SRC, OXM_OF_ARP_SHA, OXM_OF_ARP_THA, OXM_OF_IPV6_FLABEL
  - Maskable in OXM basic class but not in NXM
+ OXM_OF_TCP_SRC, OXM_OF_TCP_DST, OXM_OF_UDP_SRC, OXM_OF_UDP_DST
  - Maskable in NXM but not in OXM basic class

Do you think an oxm_maskable field is in order?

> > I'd be inclined to omit the new field types introduced by OF1.1/OF1.2,
> > such as MPLS, until we have an implementation.
> 
> Sure, that also sounds reasonable.