Re: [Qemu-devel] x86 emulated hardware : which make.conf options ?

[Natalia Portillo]

Yes, there are a lot of added instructions for P3 and P4, just see the 
Intel IA-32 manual.
For example, there is CMPXCHG16B in P4, but not in P3 nor P2.

El 01/04/2005, a las 19:04, Paul Brook escribió:

> On Friday 01 April 2005 18:26, Natalia Portillo wrote:
> > Use the same optimizations you should use in a real Pentium II.
> > You can also enable SSE and SSE2 (but not Pentium III or Pentium 4), 
> > as
> > QEMU emulates them.
>
> Do you have any facts to substatiate this statement?
>
> The pentium 2, 3, and 4 all support the same core instruction set, the 
> only
> difference being sse and sse2. From the qemu point of view a 
> pentuim3/4 is
> just a pentium2 with sse/sse2.
>
> Qemu emulates the x86 instruction set. It does not implement the
> microarchitecture of a particular implementation. I haven't done any 
> tests,
> but I'd expect the performance characteristics of qemu are 
> significantly
> different to those of a real CPU.
>
> -Os optimizes for code size, not speed. This may be faster than -O2 in 
> some
> cases, but I'd be surprised if that was true in general.
>
> Paul
>
>
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