Re: [PATCH] /proc/scsi/map

Nick Bellinger
2002-06-27T00:44:48Z

On Tue, 2002-06-25 at 11:49, David Brownell wrote:
> >>Why shouldn't there be a $DRIVERFS/net/ipv4@10.42.135.99/... style
> >>hookup for iSCSI devices? Using whatever physical addressing the
> >>kernel uses there, which I assume wouldn't necessarily be restricted
> >>to ipv4. (And not exposing physical network topology -- routing! --
> >>in driverfs.)
> >
> >
> > You can very well use driverfs to expose those attributes, and is one of
> > the things that we've been discussing at the kernel summit. driverfs will
> > take over the world. But, I still think the device is best represented as
> > a child of the phsysical network device.
>
> Which one? I'd certainly hope that drivers wouldn't have to choose which
> of the various network interfaces to register under, or register under
> every network interface concurrently. (Or only the ones they might
> conceivably be routed to go out on...) Given a bonded network link (going
> out over multiple physical drivers) that'd get hairy. And what about
> devices that host several logical interfaces? Or when the interfaces get
> moved to some other device?

I hate to kick the already deceased horse but..

This appears to be one of the larger problems that nobody (aside from
this thread :) seems to be raising. I understand Pat's logic of wanting
to keep the logical device a child of the network card, but in many
situations (espically the enterprise ones with regard multipathed IP
storage, along with David's examples above) I just dont see how that can
be done correctly in keeping all the prementioned virtual devices part
of the network device's directory in the tree.

>
> That's why I think a "non-physical" tree (not under $DRIVERFS/root) is more
> sensible in such cases. Which is not to say it's without additional issues
> (like how to establish/maintain driver linkages that are DAGs not single
> parent trees) but it wouldn't require drivers to dig as deeply into lower
> levels of their stack. (And some network interfaces might well live in
> such a non-physical tree, not just iSCSI...)
>

I am in complete agreement, from my little view of where driverfs
currently stands a non-physical tree is going to have to happen sooner
or later, why not now?

> I think that problem wouldn't quite be isomorphic to multipath access to
> devices, though it seems to be related. "Driver stacking" is an area
> that "driverfs" doesn't seem to address quite yet ... not needed in the
> simpler driver scenarios, so that's what I'd expect at this stage.
>
> - Dave
>
Thanks!
Nicholas Bellinger