On 2/7/11 1:33 PM, Khem Raj wrote: > On Mon, Feb 7, 2011 at 7:53 AM, Enrico Scholz > <[email protected]> wrote: >> Explicit '-mthumb' is required because Cortex-M3 does not support ARM >> instructions and actual flags cause gcc to fail with 'error: target CPU >> does not support ARM mode'. >> >> The '-mcpu=cortex-m3' is shorter than '-march=armv7-m -mtune=cortex-m3' >> and enables workarounds like '-mfix-cortex-m3-ldrd'. > > Does -mcpu=cortex-m3 also cause gcc to tune for cortex-m3 ?
-mcpu=cortex-m3 is equivalent to -march=cortex-m3 -mtune=cortex-m3 So in this instance, it will have a side effect of potentially changing the available set of instructions.. The existing command says the only available instructions are those defined as "armv7-m", but I want to tune the instruction scheduler for execution on "cortex-m3". (I'm not an ARM expert, so I'm not sure what is reasonable in this case.. but the arguments do have slightly different meanings.) --Mark >> >> Signed-off-by: Enrico Scholz <[email protected]> >> --- >> conf/machine/include/tune-cortexm3.inc | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/conf/machine/include/tune-cortexm3.inc >> b/conf/machine/include/tune-cortexm3.inc >> index 6da9aee..a66a33c 100644 >> --- a/conf/machine/include/tune-cortexm3.inc >> +++ b/conf/machine/include/tune-cortexm3.inc >> @@ -1,4 +1,4 @@ >> # valid options for -march: `armv7', `armv7-m' >> -TARGET_CC_ARCH = "-march=armv7-m -mtune=cortex-m3 -mfpu=vfp >> -mfloat-abi=softfp" >> +TARGET_CC_ARCH = "-mthumb -mcpu=cortex-m3 -mfpu=vfp -mfloat-abi=softfp" >> FEED_ARCH = "armv7" >> BASE_PACKAGE_ARCH = "armv7" >> -- >> 1.7.4 >> >> >> _______________________________________________ >> Openembedded-devel mailing list >> [email protected] >> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel >> > > _______________________________________________ > Openembedded-devel mailing list > [email protected] > http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel _______________________________________________ Openembedded-devel mailing list [email protected] http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel
