Date: Fri, 10 Nov 2006 17:09:11 -0500 From: Michael Proto <mproto@secureworks.com> To: "Jason C. Wells" <jcw@highperformance.net> Cc: freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: Compiler Options Message-ID: <4554F887.5000806@secureworks.com> In-Reply-To: <4554D43E.5010700@highperformance.net> References: <4554D43E.5010700@highperformance.net>
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>From /usr/src/sys/conf/kern.mk:
# On the i386, do not align the stack to 16-byte boundaries. Otherwise GCC
# 2.95 adds code to the entry and exit point of every function to align the
# stack to 16-byte boundaries -- thus wasting approximately 12 bytes of
stack
# per function call. While the 16-byte alignment may benefit micro
benchmarks,
# it is probably an overall loss as it makes the code bigger (less efficient
# use of code cache tag lines) and uses more stack (less efficient use
of data
# cache tag lines). Explicitly prohibit the use of SSE and other SIMD
# operations inside the kernel itself. These operations are exclusively
# reserved for user applications.
#
.if ${MACHINE_ARCH} == "i386" && ${CC} != "icc"
CFLAGS+= -mno-align-long-strings -mpreferred-stack-boundary=2 \
-mno-mmx -mno-3dnow -mno-sse -mno-sse2
INLINE_LIMIT?= 8000
.endif
-Proto
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?
>
> Thanks,
> Jason C. Wells
> _______________________________________________
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--
Michael Proto | SecureWorks
Unix Administrator |
PGP ID: 5D575BBE | mproto@secureworks.com
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