[openib-general] ib_gid_is_link_local

[Hal Rosenstock]

Hi Jason,

On Tue, 2007-01-02 at 18:00, Jason Gunthorpe wrote:
> On Tue, Jan 02, 2007 at 04:42:23PM -0500, Hal Rosenstock wrote:
> 
> > > I propose changing the routine name to ib_gid_is_default_prefix so as
> > > not to be misleading. Comments ? Patch to follow for this.
> > 
> > What is confusing is the link local unicast GID definition in Figure 39.
> > It says 54 bits of and is green (which I think means 0 as in Figure 40)
> > on p. 144-145.
> 
> I think you are right about the 0s (see definition of GID Prefix).
> Based on the definition of GID Prefix (and the IPv6 addressing
> architecture this section is clearly derived from) I'd also change
> ib_gid_is_link_local to check only the scope bits (ie compare a /10
> not a /64..)

I was wondering about that too and was about to go there. So you are
saying that any link local scope GID is fine (and doesn't need complete
64 bit matching but only the first 10 bits), right ?

> BTW, I think ib_gid_is_link_local is a fine name for the function as
> is and matches the various specifications. The test you described:

Agreed. I came back around to that conclusion once I became
unconfused...

> > > > Shouldn't it be either the default subnet prefix or the one supplied in
> > > > PortInfo:GidPrefix (which might not be the default one) ?
> 
> Would be better described as ib_gid_is_on_link. on-link being a term
> used to refer to an address where a routing table says it is present
> on the local link rather than reachable through a router.

Yes, that is better terminology but I can't use this yet as there is no
routing table (at least yet)...

> It looks like you are making alot of progress here on router support -
> I'm looking forward to trying it!

Thanks and I look forward to getting feedback from real routers :-)

-- Hal

> Jason