kern/131571: Running with APIC enabled crashes a Supermicro server running 7.0/7.1

[Matt Hempel]

I received the following feedback from the freebsd-smp list:

Look for a BIOS update. The last time I saw this, some weird interaction 
with SMM was interfering with the delivery of the INIT and/or STARTUP 
IPIs. A BIOS update that included newer microcode for the CPUs in 
question fixed the issue. For the boxes I was testing, if I disabled USB 
legacy compat (which would result in fewer SMM traps during boot), then 
the machines would fail to boot every time. With USB legacy compat 
enabled, they would fail occasionally.

-- John Baldwin


Updating the BIOS sounds like a good idea to me.  That's going to take 
some time to accomplish.  I'll update the PR when I get it done; 
anything else you can suggest in the meantime would be much appreciated.

Thanks

M