Announcing ethernet link state changes via route socket

[Matthew Dillon]

:Announcing link state changes to the userspace via route socket is critical
:to get routing related applications to work correctly - routing protocols
:are most important, but other applications might benefit from it as well.
:
:This code is adapted from OpenBSD and is only the first basic step in path
:to get correct support. Only em(4) is tested because I don't have hardware
:to test others, although bge(4) might get my attention as well in the
:future. 
:
:There is one fundamental problem I'd like to get feedback about from
:developers - how to make various kernel stuff react on link state changes?
:For example various interfaces which are somehow attached to the interface
:(bridges, carp, vlans etc) should react. Ideally routing table should react
:as well (yes, no BSD or Linux kernel does that yet, but they should).
:Personally I like the idea of the hooks OpenBSD uses, but as I'm not very
:familiar of DragonFlyBSD, my personal opinion might be very far from good
:solution ;).
:
:regards,
:
:-- 
:Hasso Tepper

    It won't build straight out of the box since a number of other
    drivers are still using the existing if_link_state_change() function
    call.  I kinda prefer the if_link_state_change(ifp, state) API 
    rather then the ifp->if_link_state = ...; if_link_state_change(ifp) API.

    I agree with the work, though... I'd like to see this in DragonFly
    once it gets cleaned up a bit.

    There seem to be a few other changes mixed into your patch.  What's
    the baudrate part of the patch?  (I like it, I'm just not sure how
    its related to the linkstate work).

						-Matt