-march specifies which ISA to use. -mtune specifies which cpu-type to optimize instruction ordering for, but not which ISA to use. There are times when it may make sense to specify mtune=generic and use a more specific march, such as core2, but the opposite makes little sense at all: use cpu-type specific ISA, but order the instructions generically. While the -mtune is implied by -march, gcc does not verify it is using -mtune=core2 with:
gcc -Q -march=core2 --help=target Explicitly specify -mtune=core2 to be sure. Add a comment header describing the CPUs targeted by this tune file. Signed-off-by: Darren Hart <dvh...@linux.intel.com> Cc: Richard Purdie <richard.pur...@linuxfoundation.org> Cc: Paul Eggleton <paul.eggle...@intel.com> Cc: Tom Zanussi <tom.zanu...@intel.com> Cc: Nitin Kamble <nitin.a.kam...@intel.com> Cc: Mark Hatle <mark.ha...@windriver.com> Cc: Bruce Ashfield <bruce.ashfi...@windriver.com> Cc: Martin Jansa <martin.ja...@gmail.com> --- meta/conf/machine/include/tune-core2.inc | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/meta/conf/machine/include/tune-core2.inc b/meta/conf/machine/include/tune-core2.inc index 85b6924..3b25197 100644 --- a/meta/conf/machine/include/tune-core2.inc +++ b/meta/conf/machine/include/tune-core2.inc @@ -1,10 +1,18 @@ +# Settings for the GCC(1) cpu-type "core2": +# +# Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3 +# instruction set support. +# +# This tune is recommended for the Intel Core 2 CPU family, including Conroe, +# Merom and beyond, as well as the first Atom CPUs, Diamondville, and beyond. +# DEFAULTTUNE ?= "core2" require conf/machine/include/tune-i586.inc # Extra tune features TUNEVALID[core2] = "Enable core2 specific processor optimizations" -TUNE_CCARGS .= "${@bb.utils.contains("TUNE_FEATURES", "core2", " -march=core2 -msse3 -mtune=generic -mfpmath=sse", "", d)}" +TUNE_CCARGS .= "${@bb.utils.contains("TUNE_FEATURES", "core2", " -march=core2 -mtune=core2 -msse3 -mfpmath=sse", "", d)}" # Extra tune selections AVAILTUNES += "core2" -- 1.7.9.5 _______________________________________________ Openembedded-core mailing list Openembedded-core@lists.openembedded.org http://lists.openembedded.org/mailman/listinfo/openembedded-core