MacBook users: possible fix for the SMP problem

[Mark Tinguely]

>  I don't really like the fact that it has to be turned on manually. Is it 
>  possible to make this automatic based on BIOS Id or something like this?
>
>  -Maxim

(Thread summary because of text removal - "On some systems, namely MacBooks
 we need to disallow the legacy USB circuit to generate an SMI# because this
 can  cause several problems, namely: incorrect CPU frequency detection and
 failure to start the APs." - taken from patch explaination).

This sounds like a great compiler option / C code definition. It can be
compiled into kernel and left as the default if you need it. It should
not go into GENERIC.

--Mark Tinguely.