From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1DHQm3-00042z-6B for qemu-devel@nongnu.org; Fri, 01 Apr 2005 13:21:39 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DHQlx-00040H-AG for qemu-devel@nongnu.org; Fri, 01 Apr 2005 13:21:35 -0500 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DHQlw-0003zC-Mi for qemu-devel@nongnu.org; Fri, 01 Apr 2005 13:21:32 -0500 Received: from [65.74.133.9] (helo=mail.codesourcery.com) by monty-python.gnu.org with esmtp (TLSv1:DES-CBC3-SHA:168) (Exim 4.34) id 1DHQVE-0007wL-BC for qemu-devel@nongnu.org; Fri, 01 Apr 2005 13:04:16 -0500 From: Paul Brook Subject: Re: [Qemu-devel] x86 emulated hardware : which make.conf options ? Date: Fri, 1 Apr 2005 19:04:07 +0100 References: <1110228937.3297.18.camel@penguin> <1112360704.11489.11.camel@penguin> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200504011904.12228.paul@codesourcery.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org 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