Re: [patch net-next RFC 0/4] introduce infrastructure for support of switch chip datapath

[tgraf <tgraf@suug.ch>]

On 03/25/14 at 01:00pm, Florian Fainelli wrote:
> 2014-03-25 12:40 GMT-07:00 Neil Horman <nhorman@tuxdriver.com>:
> > On Tue, Mar 25, 2014 at 11:33:22AM -0700, Florian Fainelli wrote:
> >> 2014-03-25 10:39 GMT-07:00 Neil Horman <nhorman@tuxdriver.com>:
> >> > 1) Ports on a switch chip are accessed using net_device structures, but
> >> > registered to a private list contained within the switch device, rather than to
> >> > the net namespaces device list.
> >>
> >> I think this would be a good model for simple embedded switches that
> >> only support 802.1q VLANs for instance, since we won't be able to get
> >> any actual data to be sent/received to any per-port netdevice, those
> >> per-port netdevices would only be effective for control at the L2
> >> level.
> >>
> >> For switches that do support tags, I think we do want per-port
> >> netdevices to appear in the regular netdevices namespace as those
> >> might be able to get actual data sent to/received from by using these
> >> tags, at least momentarily until a higher-level entity decides
> >> otherwise (e.g: by bridging, disabling interfaces...).
> >>
> > Well, perhaps thats the answer then  - Augment the model to allow for the
> > registration of net_devices to private lists within a switch device, but don't
> > require it.  If a given chip supports the assignment of L3 data by the cpu, the
> > use of iptables etc, let the switch driver do so, its not like we can't do that
> > already, but for the smaller devices, keeping them tightly controled via the
> > switch driver in such a way that user space can only access them with permission
> > from the switch driver.
> >
> > Does that seem reasonable?
> 
> Sure that looks good, the switch driver will know what L2/L3 features
> it has, and the higher levels will know how to utilize that
> information to construct the net_devices stacking and namespacing.


I think all it takes is to correctly apply the existing separation
which is already available but not applied right now.

We already have the L2/L3 separation in place:

net_device vs in_device/inet6_dev/....

A pure L2 device that will never do L3 on the CPU would only
need to set a flag which we check before allocating a in_device
and therefore prevent from all the L3 configs to be exposed.