32-bit stuff on an x86-64 box???

[Walter Dnes]

On Thu, Jun 09, 2005 at 10:40:28PM -0400, William Park wrote
> On Wed, Jun 08, 2005 at 02:40:23PM +0800, JM wrote:
> > hi,
> > 
> > 	we will be buying a 64-bit box, i was wondering if i need to
> > 	recompile my kernel for this?
> 
> Answer is "No".  Speaking from i386 vs. i686 experience, I barely
> noticed the difference.  Screen updates were faster, but not by that
> much.

  A 64-bit cpu running in 32-bit compatability mode makes as much sense
as buying a Mac, and using an emulator to run nothing but Windows apps.
Save yourself some money, and buy the real thing.

  If you can compile most or all of your apps to run in 64-bit mode,
then you can expect genuine improvement in cpu-constrained apps.  Any
compile-from-source distro (Gentoo, LFS, Slack, etc) should benefit.
See the article at http://www.devx.com/amd/Article/16018 for details.
To summarize...

  - general-purpose registers (GPRs) increased from 8 in x86-32 to 16
    and, of course, their size is now 64 bits

  - 128-bit XMM registers (used for Streaming SIMD instructions)
    increased from 8 to 16.

  One big complaint about X86/32bit cpus has been the limited number of
registers.  The extra registers on the AMD64 reduce the need for memory
accesses, and a compiler that knows about them can speed up calculations
significantly.

  Now let's talk about 32-bit stuff on an x86-64 box (which is why I
changed the thread subject).  The AMD64 has 32-bit compatability in
64-bit userland.  Is anybody running in 64-bit mode and have binary-only
stuff like Macromedia/Adobe's Schlockwave-Trash, Sun's Java, and
OpenOffice (depends on Sun's Java) working in 64-bit userland?

  What about parts of *KERNEL MODE* code being 32-bits in a 64-bit
environment?  I'm talking about nVidia's proprietary video-card drivers.
And let's not forget nVidia's mother boards, which are often the base
for AMD64 cpus.  Anybody got the motherboard's built-in video/sound/nic
working whilst running the cpu in 64-bit mode?

-- 
Walter Dnes <waltdnes-SLHPyeZ9y/tg9hUCZPvPmw at public.gmane.org>
My musings on technology and security at http://tech_sec.blog.ca
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