64-bit Kernel Question

[Dave Jones]

On Tue, Mar 10, 2009 at 10:08:52AM -0700, Adam Williamson wrote:
 
 > Video encoding is also one of the few things that may get a boost from
 > the post-i586 instruction set enhancements (MMX, SSE, 3DNow!, all that
 > crap), which can't be used in i586 packages but are used in x86-64
 > packages, as all x86-64 CPUs support them so it's safe.
 
As long as the feature presence is tested before use, there's no
reason that they can't be used in 586 packages.

MMX was on the 586 Pentiums, AMD K6's, Cyrix, VIA..
3dnow was on 586 class VIA
sse was on 586 class VIA

Just because the default compiler flags are targetted to an instruction
set doesn't stop a package building a .so of optimised routines and
picking the right one at runtime.  (Or several other methods of accomplishing
the same thing)

	Dave

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