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Re: Multiarch crazyiness



On Mon, 2007-10-22 at 12:20 -0400, Jesse Keating wrote:
> On Mon, 22 Oct 2007 12:03:05 -0400
> Matthew Saltzman <mjs CLEMSON EDU> wrote:
> 
> > 32-bit runtime in general?  Why?  (Not a critical "why", a genuinely
> > curious "why"...)
> 
> On those arches, running 64bit code comes at a penalty.  In fact, even
> on x86_64 there is a penalty.  Larger memory overhead.  However on
> x86_64 the extra CPU registers gained by running in x86_64 mode
> outweigh the memory overhead.  Not the case on ppc/sparc where there
> are no 'extra registers' to gain.  Very little software in very few
> situations need 64bit.

So on those archs one would want a 64-bit kernel and 32-bit apps, except
for large-memory programs or those needing 64/128-bit numerical types
(self-developed code, for example)?

Is that how it's actually handled by the installer?
-- 
                Matthew Saltzman

Clemson University Math Sciences
mjs AT clemson DOT edu
http://www.math.clemson.edu/~mjs


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