igb(4) and VLAN issue?

From: Kevin Bowling <kevin.bowling_at_kev009.com>
Date: Mon, 02 Aug 2021 17:51:46 UTC

I caught wind that an igb(4) commit I've done to main and that has
been in stable/12 for a few months seems to be causing a regression on
opnsense.  The commit in question is

The report is at:

I haven't heard of this issue elsewhere and cannot replicate it on my
I210s running main.  I've gone over the code changes line by line
several times and verified all the logic and register writes and it
all looks correct to my understanding.  The only hypothesis I have at
the moment is it may be some subtle timing issue since VLAN changes
unnecessarily restart the interface on e1000 until I push in a work in
progress to stop doing that.

I'd like to see the output of all the processes or at least the
process configuring the VLANs to see where it is stuck.  Franco, do
you have the ability to 'control+t' there or otherwise set up a break
into a debugger?  Stacktraces would be a great start but a core and a
kernel may be necessary if it isn't obvious.