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Message-ID: <53B2679F.10009@ozlabs.ru>
Date: Tue, 01 Jul 2014 17:47:43 +1000
From: Alexey Kardashevskiy <aik@ozlabs.ru>
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Subject: Re: [Qemu-devel] [PATCH fix for 2.1 v2] makefile: Fix tools compile
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To: Paolo Bonzini <pbonzini@redhat.com>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>

On 07/01/2014 05:41 PM, Paolo Bonzini wrote:
> Il 01/07/2014 09:30, Alexey Kardashevskiy ha scritto:
>> The existing test whether "-lm" needs to be included or not is
>> insufficient as it reports false negative on Fedora20/ppc64.
>> This happens because sin(0.0) is a constant value which compiler
>> can safely throw away and therefore there is no need to add "-lm".
>> As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.
>>
>> This adds a global variable and uses it in the test to prevent
>> from optimization.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>>
>> ---
>> Changes:
>> v2:
>> * previous s/sin/log/ replacement removed, a global variable is
>> used instead
>> ---
>>  configure | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/configure b/configure
>> index 23ecb37..6dd44a9 100755
>> --- a/configure
>> +++ b/configure
>> @@ -3453,7 +3453,7 @@ fi
>>  # Do we need libm
>>  cat > $TMPC << EOF
>>  #include <math.h>
>> -int main(void) { return isnan(sin(0.0)); }
>> +double x; int main(void) {return isnan(sin(x));}
>>  EOF
>>  if compile_prog "" "" ; then
>>    :
>>
> 
> Can you please test with this hunk on top:
> 
> diff --git a/Makefile.target b/Makefile.target
> index 6089d29..137d0b0 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -163,10 +163,6 @@ dummy := $(call unnest-vars,.., \
>  all-obj-y += $(common-obj-y)
>  all-obj-$(CONFIG_SOFTMMU) += $(block-obj-y)
> 
> -ifndef CONFIG_HAIKU
> -LIBS+=-lm
> -endif
> -
>  # build either PROG or PROGW
>  $(QEMU_PROG_BUILD): $(all-obj-y) ../libqemuutil.a ../libqemustub.a
>      $(call LINK,$^)
> 
> It should now be unnecessary.


Tried, all good.


-- 
Alexey