Proof of concept patch for device rearrangement

[walt]

Poul-Henning Kamp wrote:

> I have uploaded a proof of concept patch:
> 
> 	http://phk.freebsd.dk/patch/fd_dev.patch


> ...And with this code enabled, it is possible to go from userland to
> device driver without touching Giant underway.

I'm sorry, I can't parse that last sentence.  Could you explain in
25 words or less (or 3 lines of code) what it means?

'Giant' is the lock that Alan is trying to get rid of?

Thanks!