use only one core of dual core system

[Bill Rees]

    I'm trying to isolate a driver problem that appears to be smp 
related so I would like to take the system with the smp kernel and boot 
it so that only one cpu is used.  Ideally, I'll be able to tell if 
running off of two cores is causing problems with the usb driver.
So the only thing I've found that I can pass to the kernel during boot 
is maxprocs which doesn't seem to actually deal with the number of cpus 
but rather the number of processes. 

    Is there any boot variable that will prevent the second cpu from 
coming up?

bill