From: Mark Hatle <mark.hatle@windriver.com>
To: openembedded-devel@lists.openembedded.org
Cc: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
Subject: Re: [PATCH] cortex-m3: adjusted target cflags
Date: Mon, 07 Feb 2011 13:39:42 -0600 [thread overview]
Message-ID: <4D504A7E.4030809@windriver.com> (raw)
In-Reply-To: <AANLkTinsSoak9h=B+TQEzoUvWSP+MVELZQkTFRu3PTOQ@mail.gmail.com>
On 2/7/11 1:33 PM, Khem Raj wrote:
> On Mon, Feb 7, 2011 at 7:53 AM, Enrico Scholz
> <enrico.scholz@sigma-chemnitz.de> 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 <enrico.scholz@sigma-chemnitz.de>
>> ---
>> 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
>> Openembedded-devel@lists.openembedded.org
>> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel
>>
>
> _______________________________________________
> Openembedded-devel mailing list
> Openembedded-devel@lists.openembedded.org
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next prev parent reply other threads:[~2011-02-07 19:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-07 15:53 [PATCH] cortex-m3: adjusted target cflags Enrico Scholz
2011-02-07 15:53 ` [PATCH] gcc-4.5: added thumb2 build patch Enrico Scholz
2011-02-07 16:35 ` Koen Kooi
2011-02-07 17:25 ` [PATCH, v2] " Enrico Scholz
2011-02-07 18:30 ` Khem Raj
2011-02-07 19:33 ` [PATCH] cortex-m3: adjusted target cflags Khem Raj
2011-02-07 19:39 ` Mark Hatle [this message]
2011-02-07 20:19 ` Khem Raj
2011-02-07 20:42 ` Mark Hatle
2011-02-07 20:59 ` Enrico Scholz
2011-02-07 21:35 ` Khem Raj
2011-02-07 22:27 ` Enrico Scholz
2011-02-07 22:35 ` Khem Raj
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