Date: Mon, 1 Mar 2010 13:24:54 -0800 (PST) From: James Phillips <anti_spam256@yahoo.ca> To: freebsd-questions@freebsd.org Subject: Re: Compiler Flags problem with core2 CPU Message-ID: <997836.8570.qm@web65512.mail.ac4.yahoo.com> In-Reply-To: <20100301100655.B3D801065676@hub.freebsd.org>
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> Date: Sun, 28 Feb 2010 22:37:27 +0800 > From: Aaron Lewis <aaron.lewis1989@gmail.com> > Subject: Re: Compiler Flags problem with core2 CPU > To: Paul B Mahol <onemda@gmail.com> > Cc: freebsd-questions@freebsd.org > Message-ID: <4B8A7FA7.1070200@gmail.com> > Content-Type: text/plain; charset=3DISO-8859-1; > format=3Dflowed >=20 > Really ? It's bad to use custom flags to compile kernel , > why do you=20 > think so ? > I'd like to know more about this : ) >=20 > So setting optimize compiler flags is only useful for > userland stuff ? >=20 I laughed at your question because I remember reading somewhere that using = aggressive optimization options is a good way to find compiler bugs. I thin= k that extends of optimizations for "new" CPU architectures as well.=20 I also heard kernel code avoids MMX instructions for some reason: it may ha= ve to do with interrupt handling (fewer registers=3Dfaster?). x86 (and AMD6= 4) processors are backwards compatible, so you don't strictly need the late= st instructions. Regards, James Phillips =0A=0A=0A ____________________________________________________________= ______=0AThe new Internet Explorer=AE 8 - Faster, safer, easier. Optimized= for Yahoo! Get it Now for Free! at http://downloads.yahoo.com/ca/internet= explorer/
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