64-bit CPU

[Lennart Sorensen]

On Wed, Sep 15, 2004 at 04:14:14AM -0700, Frank Peng wrote:
> Anybody has played with 64-bit CPU?
> How about the motherboard and other hardware?
> How Windows support 64-bit and how about other
> applications support 64-bit environment?

My wife's laptop has an athlon 64 which so far has 32bit debian i386,
32bit windows xp and 64bit windows xp on it.  So far no problems with
any of them, other than a lack of broadcom wireless drivers for 64bit xp.
We haven't tried the 64bit debian on it yet, although sometime soon we
will.  Debian has about 97% of the packages built native 64bit for it,
and the support for mixed 32/64bit is getting close to ready.  Of course
memory wise most applications don't need to be 64bit, while some do gain
in speed by running 64bit (apparently from what I have read, up to 50%
speed gain on the athlon 64 in some cases when running 64bit mode.  I
guess some code really likes being run in 64bit mode.)

Basically the athlon 64 is a very good cpu for 32bit x86 code, and an
even better cpu for 64bit x86 code.  Better than anything else currently
avaialble for x86.  intel's em64t extensions for 64bit memory space
(copying amd's instructions) provide binary compatibility, but
unfortunately none of the performance gains (often a small loss of
performance actually, except for programs that really need the extra
memory to perform well.)  It seems they tacked the instruction set on
top of the same 32bit design the chips have been all along.

Lennart Sorensen
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