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Date: Tue, 01 Jul 2014 09:54:50 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH fix for 2.1 v2] makefile: Fix tools compile
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To: Alexey Kardashevskiy <aik@ozlabs.ru>, qemu-devel@nongnu.org
Cc: Peter Maydell <peter.maydell@linaro.org>

Il 01/07/2014 09:47, Alexey Kardashevskiy ha scritto:
> 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.

Thanks, applied to scsi-next.

Paolo