Date: Fri, 04 Sep 2009 14:17:33 -0400 From: Michael Powell <nightrecon@hotmail.com> To: freebsd-questions@freebsd.org Subject: Re: cc -march questions Message-ID: <h7rlj0$se9$1@ger.gmane.org> References: <200909040510.n845AsPU024402@mp.cs.niu.edu>
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Scott Bennett wrote: > On Thu, 3 Sep 2009 10:28:09 -0400 Daniel Molina Wegener > <dmw@coder.cl> > wrote: >>2009/9/3 Scott Bennett <bennett@cs.niu.edu> >> >>> What exactly does "cc -march=prescott" enable cc to do? Does it >>> include >>> instruction scheduling for the pipeline structure of the Prescott CPUs? >>> Does >>> it include other options, e.g., "-mmmx -msse -msse2 -msse3"? >>> Thanks in advance for any information on the above! >>> >> >>According to the GCC manual page, it enables MMX, SSE, SSE2 and SSE3 >>instruction set support. >> >>Try: >>$ man 1 gcc >>/prescott >> > Thanks much for your reply. This is very bizarre. I think I've > looked > at that page at least 50 times in the past few years and somehow never saw > those lines. Sigh. :-} > I've had CPUTYPE=prescott in my /etc/make.conf for a long time now, > and I recently installed math/atlas-devel. I wonder if specifying > CPUTYPE=prescott may have caused it to choose the wrong components to > include in the final version of libalapack. If so, then I should rebuild > it without CPUTYPE=prescott. > If you do: dmesg | grep Features you will get a list of what the processor supports. You may then examine the /usr/src/share/mk/bsd.cpu.mk file looking for a match. Yes it is somewhat arcane to read, but it does list all. Notice it refers to CPUTYPE. I usually use a line such as CPUTYPE?= athlon in my make.conf. Been doing it like this for years and never had any problem. And, of course, let's not forget the MAN pages :-) YMMV -Mike
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