On 07/06/16(Tue) 22:02, Stuart Henderson wrote:
> On 2016/06/07 21:49, Vincent Gross wrote:
> > 
> > It's how henning@ set things up when integrating the new queuing mechanism.
> > http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/kern/uipc_mbuf.c#rev1.160
> > 
> > > Is there any use for this apart for vlan(4) interfaces?
> > 
> > AFAICT, no. 

In this case I'd suggest to make this a vlan(4) specific configuration,
is there a problem with that?

> My understanding is that it is also meant to be used for interface
> output queues. So you could use this to prioritize ARP over IP
> traffic if you wanted. (Well..you could anyway, but you don't
> have as many options - many switches map the priorities 0-7
> onto 4 queues so there is only lower-priority than the default
> 'prio=3').
> 
> > > Should it
> > > really be part of "struct ifnet" ?
> > > 
> > 
> > sthen@ pointed out that struct if_data was heavily used by our ports, and
> > that such a change would require a version bump. Now, I may have overlooked
> > a better place for it.
>
> I think it could go at the end of struct if_data without causing
> trouble, though since it doesn't need to be exported to userland
> isn't it better directly in ifnet rather than if_data? (if_data
> is included in RTM_IFINFO's if_msghdr, whereas you need an ioctl
> to see the non-if_data parts of struct ifnet from userland).

"struct ifnet" would be better.

> > I don't think we should make a special case for vlan(4), this kind of detail
> > do not belong to the arp(4) or bpf(4) layer.

Which kind detail are you talking about?  I still don't understand how
the scope if this problem is beyond vlan(4).  Are you also interested in
queue priority?

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