Re: Specifying names for tap interfaces

[Roger Pau Monne <roger.pau%citrix.com@localhost>]

Darren Reed wrote:
> On 6/07/2012 12:05 AM, Roger Pau Monne wrote:
> > Christos Zoulas wrote:
> > > On Jul 5,  9:37am, roger.pau%citrix.com@localhost (Roger Pau Monne) wrote:
> > > -- Subject: Re: Specifying names for tap interfaces
> > >
> > > ...
> > > | I haven't tried yet, but I assume passing the fd to Qemu will work, and
> > > | I plan on using that to fix the Qemu problem. Anyway I had this half
> > > | done, because I think it's an interesting feature, not only as a fix to
> > > | the Qemu issue.
> > >
> > > Yes, but it is a solution looking for a problem. Until we actually have
> > > a use that makes this feature necessary, we should not add it just to avoid
> > > creeping featurism and complexity.
> > >
> > > | For example being able to name Xen virtual interfaces in
> > > | the Dom0 with a user defined name (both tap and vif), but I'm sure other
> > > | users will come up with other uses.
> > >
> > > Yes, that's nice, but purely cosmetic.
> > It allows users to have persistent interfaces, even after Dom0/DomU reboot, so 
> > you can for example graph the traffic a single guest is using, which is not 
> > possible now.
>
> Being able to specify the name of a network interface is
> useful but I don't think the qemu case is the killer example.
>
> The Virtual Network Stacks project that's listed the NetBSD
> wiki would benefit greatly from this because it will allow
> each network stack to have its own "lo0" (for example) whilst
> the underlying system sees lo0, lo1, etc.
>
> Being able to rename a network device into the name of another
> also has advantages. For example, if you replace your fxp0 with
> a wm0, it may be easier to tell the system to use a different
> name than to adjust the myriad of things in /etc/rc.conf that
> use fxp0.
>
> One of the big beneficiaries of being able to rename network
> interfaces is when you have a system policy to name everything
> as "ethX" or "netX" or "lanX" because then your PXE image that
> you install doesn't need to do any tricks to work out which NIC
> is the primary one, it is always the same on all hardware. On
> top of that, if the automatic naming policy does not follow the
> mac id then replacing the first network interface with something
> else does not cause disruption if a different driver is used.

So you want to push this forward, and create an automatic naming policy? 
If I understand this right, you will no longer get bnxX or fxpX, but all 
network interfaces will be named as ethX, lanX or whatever?

> But all of these use cases require a solution that is much more
> substantial than what has currently being put forward but by
> the same token, properly solving this will enable the Xen
> problem to be addressed. I think there is more to gain by doing
> this once and doing it properly than by allowing a partial
> solution.

Yes, I don't have any objection in working on a better solution.

> As a related issue, if the output of ifconfig is going to
> contain names that do not directly relate to physical devices
> then it needs to be easier to discover them all that by doing
> "drvctl -p<nic>" on each of them.

Should the output from ifconfig include something like?

driver: bnx
device index: 0