Re: [Xen-devel] [RFC v2 1/4] bridge: enable interfaces to opt out from becoming the root bridge

[Luis R. Rodriguez]

On Wed, Feb 19, 2014 at 9:08 AM, Stephen Hemminger
<stephen@xxxxxxxxxxxxxxxxxx> wrote:
> On Wed, 19 Feb 2014 09:02:06 -0800
> "Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx> wrote:
>
>> Folks, what if I repurpose my patch to use the IFF_BRIDGE_NON_ROOT (or
>> relabel to IFF_ROOT_BLOCK_DEF) flag for a default driver preference
>> upon initialization so that root block will be used once the device
>> gets added to a bridge. The purpose would be to avoid drivers from
>> using the high MAC address hack, streamline to use a random MAC
>> address thereby avoiding the possible duplicate address situation for
>> IPv6. In the STP use case for these interfaces we'd just require
>> userspace to unset the root block. I'd consider the STP use case the
>> most odd of all. The caveat to this approach is 3.8 would be needed
>> (or its the root block patches cherry picked) for base kernels older
>> than 3.8.
>>
>> Stephen?
>>
>>   Luis
>
> Don't add IFF_ flags that adds yet another API hook into bridge.

The goal was not to add a userspace API, but rather consider a driver
initialization preference.

> Please only use the netlink/sysfs flags fields that already exist
> for new features.

Sure, but what if we know a driver in most cases wants the root block
and we'd want to make it the default, thereby only requiring userspace
for toggling it off.

  Luis
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