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SubjectRe: [PATCH RFC] iw_cxgb3: Support "iwarp-only" interfaces to avoid 4-tuple conflicts with the host stack.

Roland Dreier wrote:
> > > What's wrong with my suggestion of having the iwarp driver create an
> > > "iwX" interface to go with the normal "ethX" interface? It seems
> > > simpler to me, and there's a somewhat similar precedent with how
> > > mac80211 devices create both wlan0 and wmaster0 interfaces.
> > > - R.
> >
> > It seemed much more painful for me to implement. :-)
> >
> > I'll look into this, but I think for this to be done, the changes must
> > be in the cxgb3 driver, not the rdma driver, because the guts of the
> > netdev struct are all private to cxgb3. Remember that this interface
> > needs to still do non TCP traffic (like ARP and UDP)...
> >
> > Maybe you have something in mind here that I'm not thinking about?
> No, I was just spouting off.

At least someone is looking at my patch. ;-)

> But the whole "create a magic alias" seems kind of unfriendly to the
> user. Maybe as you said, the cxgb3 net driver could create the alias
> for the iw_cxgb3 driver?

I agree that it is not very user friendly.

My current patch just utilizes the IP address alias logic in the IP
stack. So when you do 'ifconfig ethxx:blah ipaddr up' it creates a
struct in_ifaddr which contains a ptr to the real struct net_device that
services this alias. However, from what I can tell, I cannot just
create one of these without binding an address. So the driver cannot
create the alias interface until it knows the ipaddr/netmask/etc. IE:
if you say 'ifconfig ethxx:blah up' it fails... You must supply an
address to get one of these created.

To have the cxgb3 driver create something like 'iw0', I think it would
need to create a full net_device struct. This makes the change much
more complex. But perhaps its the right thing to do...


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