Re: [Xen-devel] [Xen-users] configure.ac not correct with test about libm ? (patch included)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-07-23 at 12:59 +0100, Ian Campbell wrote:
> On Mon, 2012-07-23 at 12:49 +0100, Dieter Bloms wrote:
> > Hi,
> > 
> > I want to compile xen-unstable (last commit 25622:3c426da4788e) on
> > alpinelinux.
> > 
> > During the run of configure there is an error message like:
> > 
> > "checking for isnan in -lm... no"
> > 
> > I discussed this with the maintainer of the alpinelinux distribution
> > and he told me, that the macro in configure.ac is wrong.
> > 
> > I found out, that isnan is a macro not a function, so we have to use
> > AC_CHECK_DECLS instead of AC_CHECK_LIB.
> 
> Is isnan always macro, or just in this particular libc implementation?
> 
> Or does AC_CHECK_DECLS work right whether it is a macro or a function?
> 
> > So made this little patch to get it work:
> > 
> > --snip--
> > diff -r 3c426da4788e tools/configure.ac
> > --- a/tools/configure.ac        Sun Jul 22 16:37:25 2012 +0100
> > +++ b/tools/configure.ac        Mon Jul 23 13:43:16 2012 +0200
> > @@ -133,7 +133,7 @@
> >  AC_SUBST(zlib)
> >  AC_CHECK_LIB([aio], [io_setup], [system_aio="y"], [system_aio="n"])
> >  AC_SUBST(system_aio)
> > -AC_CHECK_LIB([m], [isnan], [], [AC_MSG_ERROR([Could not find libm])])
> > +AC_CHECK_DECLS([isnan], [], [AC_MSG_ERROR([Could not find libm])], 
> > [[#include <math.h>]])
> >  AC_CHECK_LIB([crypto], [MD5], [], [AC_MSG_ERROR([Could not find 
> > libcrypto])])
> >  AC_CHECK_LIB([ext2fs], [ext2fs_open2], [libext2fs="y"], [libext2fs="n"])
> >  AC_SUBST(libext2fs)
> > --snip--
> > 
> > maybe someone of the developers is willing to add this little patch.
> 
> Please submit patches to xen-devel according to the procedure in
> http://wiki.xen.org/wiki/SubmittingXenPatches , I've CC'd it this time
> for you
> 
> In particular it will need a Signed off by line.

Actually don't worry about this -- it turns out we didn't need libm
anyway and Dario has posted a patch to remove the check altogether.



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