2009/9/26 Jason Swails <jason.swails.gmail.com>:
> Snow Leopard
> will compile with either -m32, -m64, or neither (though I have no idea what
> it does by default).
On a 64-bit CPU, without an -mXX flag, it will generate 64-bit code,
without regard to the kernel. On a 32-bit CPU, 32-bit code.
> And one other curiosity, how can a 32-bit kernel support 64-bit memory
> addressing? Wouldn't that be the very definition of a 64-bit kernel, or am I
> missing something? I've never had this issue before Snow Leopard. (Or
> perhaps it's a 32-bit OS using a 64-bit kernel? But again, wouldn't that be
> a 64-bit OS? This is a bit too confusing.)
The kernel itself can be 32-bit, with small amounts of 64-bit code to
manage the 64-bit processes. Supporting multiple addressing schemes
for user processes in a single kernel is actually pretty common -
Windows does it for example. Most 64-bit Macs run a 32-bit kernel by
default because many device drivers are 32-bit-only.
--Tom
_______________________________________________
AMBER-Developers mailing list
AMBER-Developers.ambermd.org
http://lists.ambermd.org/mailman/listinfo/amber-developers
Received on Sun Sep 27 2009 - 09:30:02 PDT
