On Wed, Jul 25, 2007 at 11:02:46AM -0400, Stephen M. Rumble wrote:

> I don't know if it's worth having. I guess it depends on how many  
> binary blobs we expect to encounter (and I assume this is a very low  
> number). On the other hand, I'm sure it was not just changed for the  
> heck of it.
> 
> Andrew, what was the reason for this change? Performance? Code  
> simplicity? Is this just a common thing to do? I'm simply curious.

A lot of this is in the archives, but in short:

It's the most commonly used variable in the kernel, and the frequency of its
use is increasing significantly. If we get around to making system calls use
the standard C calling convention (this is actually of real benefit) then we
grow a whole new set of uses. For SMP, it's also the most convenient way to
identify the running CPU.

Andrew