From: Duan Jiong <redacted>
Date: Thu, 31 Oct 2013 19:09:56 +0800

Removing CONFIG_IPV6_ROUTER_PREF means that the Router Preference is
always on, is this understanding right?

If that's is correct, i think compatibility issues will arise. For
example, when the CONFIG_IPV6_ROUTER_PREF option is on, the kernel
should not do round-robin during default router selection, but when
the CONFIG_IPV6_ROUTER_PREF option is off, the kernel should do it.

Everyone is essentially getting it enabled right now anyways, since
%99.999999 of users run distribution kernels.  Nobody has asked
for a run-time knob for this, which therefore means that %99.999999
of users simply do not care.

Yes there are people who build their own kernels, but to tell you
the truth I doubt anyone really turns this off explicitly to turn
off router preference handling.

But I'm willing to cater to them _iff_ the RFC tells us we should
provide should a capability.