From: Linus Torvalds <torvalds@linux-foundation.org>Date: Thu, 24 Apr 2008 08:39:37 -0700 (PDT)> Heh. This is what x86 has done since day#1. I wonder why other > architectures wouldn't have copied that part..I passed it around in a register because nothing outside of the trapreturn and signal handling path needed access to it :-)