Subject: Re: [PATCH RFC 0/5] net: L2 only interfaces

From: Florian Fainelli <[email-masked]>
Date: Tue, 25 Aug 2015 16:24:36 -0700

On 25/08/15 16:20, Alexei Starovoitov wrote:
> On Tue, Aug 25, 2015 at 03:50:10PM -0700, Florian Fainelli wrote:
>> Hi all,
>>
>> This patch series implements a L2 only interface concept which basically denies
>> any kind of IP address configuration on these interfaces, but still allows them
>> to be used as configuration end-points to keep using ethtool and friends.
>>
>> A cleaner approach might be to finally come up with the concept of net_port
>> which a net_device would be a superset of, but this still raises tons of
>> questions as to whether we should be modifying userland tools to be able to
>> configure/query these interfaces. During all the switch talks/discussions last
>> year, it seemed to me like th L2-only interface is closest we have to a
>> "network port".
>>
>> Comments, flames, flying tomatoes welcome!
>>
>> Florian Fainelli (5):
>>   net: add IFF_L2_ONLY flag
>>   net: ipv4: Skip in_dev initialization for IFF_L2_ONLY interfaces
>>   net: ipv6: Skip in6_dev initialization for IFF_L2_ONLY interfaces
> 
> interesting idea! Do you know how kernel/iproute2 will react to lack of in_dev?

Surprisingly pretty good so far, have not found a way to make the kernel
crash ;)

> No crashes I'm assuming, but what kind of errors are thrown?

If you try to assign an IP address to such an interface, you get:

# ifconfig gphy 192.168.1.1
ifconfig: SIOCSIFADDR: No buffer space available

> imo great first step to have lightweight netdevs. +1 for 'net_port' in the future.

Thanks!
-- 
Florian