Is 00:00:00:00:00:00 special?

Is the all-zero MAC address special?  Thanks to an unusual hardware
situation, I just booted a SPARC such that le0 thinks its MAC is
all-0-bits.  (Booted from disk, not netboot, to be sure.)

But IPv6 failed to attach at boot time, saying it failed to get EUI64,
which is why I'm asking.  I can't recall hearing of any way in which
the all-0 MAC would be invalid, but _something_ seems to think it is;
it looks to me like a perfectly good globally-administered unicast
address.  It seems to work fine for IPv4, though of course (like any
MAC) there can be at most one such in any broadcast domain unless
you're doing something fancy.

Anybody happen to know?

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