[Qemu-devel] [PATCH fix for 2.1] makefile: Fix tools compile

[Alexey Kardashevskiy <aik@ozlabs.ru>]

The existing test whether "-lm" needs to be included or not is
insufficient as it reports false negative on Fedora20/ppc64.
As the result, qemu-nbd/qemu-io/qemu-img tools cannot compile.

This replaces sin() with log() in the test.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

---

The bug was triggered by efc6de0d0eb21bbd8fbc90da1faf7dd8ed9f5321
"block/iscsi: handle BUSY condition" which does not anything wrong :)

It compiled well on Fedora19 though what is weird.

Is log() good enough or we need to test for both?

Thanks.


ps. this is my test on the system upgraded from fc19 yesterday:

[aik@vpl2 ~]$ cat b.c
#include <math.h>
int main(void) { return isnan(log(0.0)); }

[aik@vpl2 ~]$ gcc b.c -o b
/tmp/ccqp1EI4.o: In function `main':
b.c:(.text+0x20): undefined reference to `log'
collect2: error: ld returned 1 exit status
[aik@vpl2 ~]$ gcc b.c -o b -lm
[aik@vpl2 ~]$ cat /etc/issue
Fedora release 20 (Heisenbug)
Kernel \r on an \m (\l)


---
 configure | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure b/configure
index 23ecb37..c7a2922 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)); }
+int main(void) { return isnan(log(0.0)); }
 EOF
 if compile_prog "" "" ; then
   :
-- 
2.0.0