extreme mem usage under amd64 arch ?

[John-Mark Gurney]

Astrodog wrote this message on Sat, Apr 08, 2006 at 13:36 +0800:
> On 4/8/06, Oliver Fromme <olli at lurza.secnetix.de> wrote:
> > I guess this is the most important reason:  If ints were 64
> > bits, there would be no easy way to handle 32 bit entities.
> > Not being able to handle 32 bit objects with a native data
> > type whould be a major problem, especially for an OS kernel,
> > I think.
> >
> Can an AMD64 processor actually handle 32 bits of data natively, or
> does it just knock off the last 32 bits of a 64-bit version, when its
> not in long mode?

yes, it can...  infact it defaults to 32bits unless a prefix is
provided to access 64bit registers...  (assuming a mode that 64bit
registers are accessable)..  Though as w/ most processors, the upper
32bits are still around, just on 32bit operations they are ignored...

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."