RFD: Rework/extending functionality of mdev

[Michael Conrad]

On 3/13/2015 3:25 AM, Harald Becker wrote:
>>    1 - kernel-spawned hotplug helpers is the traditional way,
>>    2 - netlink socket daemon is the "right way to solve the forkbomb
>> problem"
>
> ACK, but #2 blocks usage for those who like / need to stay at #1 / #0
>
>> In that case, I would offer this idea:
>
> All you do, is throwing in complex code sharing and the need to chose 
> a mechanism ahead at build time, to allow for switching to some newer 
> stuff ... but what about pre-generated binary versions, which 
> mechanism shall be used in the default options, which mechanism shall 
> be offered?

Please review it again.  My solution solves both #1 and #2 in the same 
binary, with no code duplication.

I suggested wrapping #2 in a ifdef for the people who don't have netlink 
at all, such as on BSD, and also anyone who doesn't want the extra bytes.

-Mike