[luau] make oldconfig - what does it do?

[Charles Lockhart]

I've been looking through the Configure script in the linux/scripts 
directory trying to figure out what exactly "make oldconfig" does, but 
I'm missing something.  I'm trying to figure out the source for the way 
the script makes its decisions.  Is it basing it off some other config 
file, is it looking at what's in the current kernel, the kernel that's 
listed in the makefile, what?

Sorry, it's a lame question.
-Charles