kern/127052: Still bridge issues - with L2 protocols such as PPPoE

[Helge Oldach]

I have tested Eygenes patch and it works as expected on 6-STABLE.

However the behaviour is a little bit strange: The sysctl is of by
default. When enabling it, nothing happens. The bridge's MAC still is
the random MAC chosen upon boot. Even toggling the bridge interface
down/up doesn't change it. The bridge's MAC is inherited only when a
member interface is added or deleted. Essentially this sysctl must be
set at boot time, e.g. in /etc/sysctl.conf to make it work consistently.

Further, it is a global sysctl that applies to *all* bridge interfaces
identically. It is not possible to have one bridge with inheritance, and
another without.

Philip explained that the main rationale for MAC inheritance was to make
DHCP consistent over reboots. This can be simply achieved by a trivial

	ifconfig_bridge0="link 66:fc:df:e2:3f:f5 up"

(or similar) in /etc/rc.conf. There is no need to change code at all to
achieve the desired effect, and we still have full flexibility, even
with multiple bridges. (To simplify mass deployment, one can seed the
MAC in the above command from a file created upon initial boot.)

I would therefore mandate to back out the bridge inheritance stuff
completely.

Helge