Re: [RFC PATCH 32/33] Add the Xen virtual network device driver.

From: jamal
Date: Tue Jul 18 2006 - 08:39:23 EST

On Tue, 2006-18-07 at 12:27 +0200, Arjan van de Ven wrote:

> Hmmm maybe it's me, but something bugs me if a NIC driver is going to
> send IP level ARP packets... that just feels very very wrong and is a
> blatant layering violation....

It is but the bonding driver has been setting precedence for years now
on sending ARPs from a driver;->
It does make a lot of sense to put it in user space. More interesting
policies may include sending more than just ARPs and once you hard-code
in the kernel you loose that flexibility.

> shouldn't the ifup/ifconfig scripts just
> be fixed instead if this is critical behavior?

I dont think the ifup/ifconfig provide operational status (i.e link
up/down) - or do they? If they can be made to invoke scripts in such
a case then we are set.

Note: you will get netlink events when devices are created or devices
change their admin (via ifconfig) or operational (link down/up) status.
[Try running "ip monitor" to see]

One could write a little daemon that reacts to these specific events.
The problem has been some people claiming that daemons are a bad idea
from a usability perspective. Patrick has mentioned he may be working on
a daemon in user space that does exactly that. The other alternative is
to do the udev thing and have the kernel invoke a script whenever an
event of interest happens.


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