Probable Stupid Question: Using 64-bit Code on 64-bit Processors running 32-bit Windows... #2

Hi,

Does anyone know if it is possible to do 64-bit processing (probably by
writing some assembly language code) when running on a 64-bit CPU under
32-bit Windows?

As near as I can tell, one has to develop all 64-bit code on a 64-bit
machine running 64-bit windows and the target machines for 64-bit code have
to be 64-bit machines running 64-bit windows.

What might be useful, if it is possible, would be being able to detect a
64-bit processor when running 32-bit windows and take advantage of that to
speed up some calculations.

DanH



0
Dan
3/21/2008 6:45:06 PM
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Dan Hale wrote:

> Does anyone know if it is possible to do 64-bit processing (probably by
> writing some assembly language code) when running on a 64-bit CPU under
> 32-bit Windows?
> 


Very difficult, probably im-pos-sible ("impossible" is not French, said
Napoleon). It may look analogous to, but alas! is quite different from the
situation where you need to do 32-bit calculations (and addressing) on a
processor running in 16_bit mode. Switching an X86-64 capable processor to
64-bit "long mode" prerequires setting special virtual and paging modes,
which are incompatible with the operation of Win 32 IMHO.



-- 
Ninho
0
Ninho
3/21/2008 7:14:53 PM
Thanks!

So the hardware design is the problem. It makes sense that I couldn't find 
anything about it in searching the Internet a while back.

I guess the best we might be able to do would be to detect when a 32-bit 
application is running under WOW32 on 64-bit windows and maybe do something 
under those circumstances. I suspect that it isn't worth the trouble, and 
that it would be easier to just have a separate 64-bit version.

DanH


"Ninho" <don't.use.this!@example.net> wrote in message 
news:fs11fc$2o84$1@news.grc.com...
> Dan Hale wrote:
>
>> Does anyone know if it is possible to do 64-bit processing (probably by
>> writing some assembly language code) when running on a 64-bit CPU under
>> 32-bit Windows?
>>
>
> Very difficult, probably im-pos-sible ("impossible" is not French, said
> Napoleon). It may look analogous to, but alas! is quite different from the
> situation where you need to do 32-bit calculations (and addressing) on a
> processor running in 16_bit mode. Switching an X86-64 capable processor to
> 64-bit "long mode" prerequires setting special virtual and paging modes,
> which are incompatible with the operation of Win 32 IMHO.
> -- 

> Ninho


0
Dan
3/21/2008 7:37:16 PM
While Dan Hale dreams of electric sheep...:
> Thanks!
> 
> So the hardware design is the problem. It makes sense that I couldn't find 
> anything about it in searching the Internet a while back.
> 
> I guess the best we might be able to do would be to detect when a 32-bit 
> application is running under WOW32 on 64-bit windows and maybe do something 
> under those circumstances. I suspect that it isn't worth the trouble, and 
> that it would be easier to just have a separate 64-bit version.

It's not really a hardware problem, the problem is that you are
coding 64 bit in a 32 bit platform. You have a 32 bit middleman
between the 64 bit code you want to build and the 64 bit architecture.

For instance, I had tried to install 64bit software in the factory
installed Vista on my AMD64 machine, only to find I couldn't because
it was a 32 bit Vista.

-- 
Where's there's smoke
There are mirrors.
0
DarkWolf
3/22/2008 4:04:59 AM
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