Re: [Qemu-devel] precompiled qemu-system-x86_64 is 32 bit instead of 64bit

[Andrew Warkentin]

Laurent Desnogues wrote:

> On 2/21/08, Andrew Warkentin <address@hidden> wrote:
>  
>
> > Why does it matter if it is 64-bit or not? Most programs at the moment
> > don't benefit from being compiled 64-bit. I don't get the obsession with
> > 64-bitness that most Linux and BSD people seem to have.
> >    
>
> I have programs that run significantly faster when targetting x86_64
> (Othello back-end solver, various prime sieves, interpreted simulator,
> MAME [cf. http://aarongiles.com/pix/benchmarks.png])., where
> significantly means >10%.  I agree I can't qualify my list as "most
> programs", but on the other hand I have yet to see one of my
> programs running slower as x86_64 bit mode (though I guess some
> programs with heavy usage of pointers could be in trouble).
>
> Did anyone compare qemu ia32 vs x86_64?
>
>
> Laurent
>
>
>
>  
I guess on x86, there is somewhat of a benefit, because of the extra 
registers. On any decent architecture, 32- and 64-bit programs would run 
at the same speed. Still, I don't think that it's worth having separate 
32- and 64-bit versions of operating systems over, even on x86.