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Re: [Qemu-devel] x86 emulated hardware : which make.conf options ?
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] x86 emulated hardware : which make.conf options ? |
Date: |
Fri, 1 Apr 2005 19:04:07 +0100 |
User-agent: |
KMail/1.7.2 |
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