network-related deadlock

[Maxime Villard <max%m00nbsd.net@localhost>]

There appears to be a network deadlock somewhere in the kernel. I've narrowed
the issue down to the following situation: if you have a NetBSD vm on
VirtualBox, with one CPU, and one enabled network card that is not attached
(Settings->Network->Adapter_1->Attached_To = Not attached), the kernel freezes
~ten seconds after booting.

I can log in, type a few commands, and then the keyboard does not answer anymore
and system deadlocks (no pings either).

I've disassembled %rip, it points to x86_pause(). So there must be a deadlock.

If the card settings are switched to "Bridged Adapter" there is no deadlock.

A kernel from December 27 works fine.

Maxime