Date: Fri, 10 Nov 2006 14:24:34 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: "Jason C. Wells" <jcw@highperformance.net> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Compiler Options Message-ID: <20061110222434.GA76724@icarus.home.lan> In-Reply-To: <4554D43E.5010700@highperformance.net> References: <4554D43E.5010700@highperformance.net>
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On Fri, Nov 10, 2006 at 11:34:22AM -0800, Jason C. Wells wrote: > I have set CPUTYPE=p3 in make.conf. When I compile my kernel I see > -march=pentium3 as I expect. I also see -mno-mmx and -mno-sse are set > which I do not expect given that -march=pentium3 is used. I presume > that I want MMX and SSE since my processor supports it. What options do > I set and where do I set them to get a kernel properly tuned for pentium3? The kernel will "support" MMX and SSE -- that is, any programs (root or userland) which use MMX/SSE will work just fine. That is: any programs built with gcc can indeed support MMX and SSE operations. The kernel itself _will not_ use any SSE or MMX operations when built. This is because these optimisations are known to break the FreeBSD kernel. This applies to all i386 architectures, and probably 64-bit architectures too (not sure). CPUTYPE=p3 (or pentium4, or any other type) will not change this behaviour. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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