[ovs-dev] [mcgroup 2/4] datapath: Hardcode vport multicast group ID on older kernels.

[Jesse Gross]

Not really, I don't have any particular opinion on the actual number.
The only thing that I was concerned about is what it would look like
if we want to do this with the multicast groups for other families.

On Thu, Sep 15, 2011 at 4:40 PM, Ethan Jackson <ethan at nicira.com> wrote:
> Based on my offline discussions with Jesse I arrived, rather
> arbitrarily, at the number 214.  I don't know enough about the kernel
> to judge what a good number choice would be.  Jesse seemed to think
> larger was better.  I'll use whatever the two of you think is best.
>
> Ethan
>
>
> On Thu, Sep 15, 2011 at 16:31, Ben Pfaff <blp at nicira.com> wrote:
>> On Thu, Sep 15, 2011 at 04:10:55PM -0700, Ethan Jackson wrote:
>>> > Where does the number 214 come from?
>>>
>>> Experimentally I found that the number had to be fairly small.  I
>>> wanted it to be large enough to be unlikely conflict to values the
>>> proper way.  I also wanted a number which was arbitrary to avoid
>>> conflicting with other people who may be improperly hardcoding values
>>> like this.
>>
>> We already use genetlink groups 16 through 31 (see
>> datapath/linux/compat/genetlink-openvswitch.c) and group 32 (see
>> datapath/linux/compat/genetlink-brcompat.c).  I don't think it makes
>> sense to skip all the way to 214.  Even in 2.6.37 I only see a total
>> of 11 defined genetlink multicast groups, so I doubt that anyone's
>> going to backport a bunch of them to RHEL 5.
>>
>