Subject: Re: Regarding offloading IPv6 addrconf and ndisc

From: Jamal Hadi Salim <[email-masked]>
Date: Fri, 28 Jul 2006 08:45:37 -0400

On Fri, 2006-28-07 at 09:34 +0100, Hugo Santos wrote:

> > 2. What if user process dies? or gets overwhelmed?
> >    One of the assumptions of the any well designed kernel is that the system should never
> >    hang because some user application died or waited for ever.
> 
>    Of course that this is a real problem. However, if the control daemon
>  dies the kernel won't die. Depending on the implementation -- you might
>  temporarily get out of addresses, if the addresses are flushed when the
>  control daemon dies, etc. But, just like a routing daemon is critical
>  to a router, this control application would also be critical to the
>  host's connectivity. And if it dies, it needs to be restarted. The
>  application might be itself complex, but in the end we moved this
>  complexity away from the kernel.
> 

Hugo,

The biggest challenge you will face is the view that people hate daemons
- mostly from a usability perspective (is the gist of the arguements i
have seen) but also because of concerns such as the one Stephen mentions
above. 
I hold the same views as you do on the separation of control from the
datapath and to respond to Stephens assertion on well designed kernel
above: It is good kernel abstraction to separate policy management from
mechanisms.

The certificate issue only validates further this pov: that control
tends to be feature-rich, swiss-army knife i.e more moving target than
datapath. Such things typically belong to user-space.
I have also seen talk of secure ARP; i wonder if there may be
certificates involved there as well? If you look at the archives on
netdev you may notice such discussions. Summary: I violently agree with
you and i think if you address the "daemon" concerns, you will get other
folks to agree as well.

cheers,
jamal