Re: [Xen-devel] odd configure warnings on ARM

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2012-03-16 at 09:22 +0000, Roger Pau Monnà wrote:
> 2012/3/16 Ian Campbell <Ian.Campbell@xxxxxxxxxx>:
> > On Fri, 2012-03-16 at 09:01 +0000, Roger Pau Monnà wrote:
> >> 2012/3/15 Ian Campbell <Ian.Campbell@xxxxxxxxxx>:
> >> > Hi Roger,
> >> >
> >> > I'm seeing:
> >> >        checking for python version >= 2.3 ... yes
> >> >        configure: WARNING: Strange ldflag found in python-config output: 
> >> > -Xlinker
> >> >        configure: WARNING: Strange ldflag found in python-config output: 
> >> > -export-dynamic
> >> >        configure: WARNING: Strange ldflag found in python-config output: 
> >> > -Wl,-O1
> >> >        configure: WARNING: Strange ldflag found in python-config output: 
> >> > -Wl,-Bsymbolic-functions
> >> >
> >> > This seems to be tools/m4/python_devel.m4. Is there any reason to print
> >> > hte unknown flags?
> >>
> >> Ian Jackson requested for this, as it was not originally part of my patch:
> >>
> >> http://lists.xen.org/archives/html/xen-devel/2012-03/msg00762.html
> >>
> >> But I don't really think it's necessary/useful for the end user.
> >
> > (adding Ian)
> >
> > I don't think that configure should be concerning itself with whatever
> > random stuff the python developers feel it necessary to include in their
> > LDFLAGS other than the one we need to look at.
> >
> > I'm not sure why we are filtering the result of python-config though.
> > Shouldn't a test compile using Python.h be using the full set of
> > whatever python-config says we should use?
> 
> I'm filtering python-config output to detect which python library to
> use, since python libraries have the version number attached
> (-lpython2.6 or -lpython2.7 ...), so I need to know the exact name of
> the library we are using to perform the correct AC_CHECK_LIB call,
> which can only test a library at a time, so I can not use "-lpython2.6
> -Xlinker -export-dynamic ..." as an argument to AC_CHECK_LIB.

Will -lpython2.6 work without these other things though?

What about setting LDFLAGS to include the pythohn-config output while
testing -lpython2.6. Perhaps filtering only python2.6 from the flags?

This doesn't seem like the sort of problem we would be the first to
encounter. Google found
http://www.gnu.org/software/autoconf-archive/ax_python.html 
The second hit was
http://git.savannah.gnu.org/gitweb/?p=autoconf-archive.git;a=blob_plain;f=m4/ax_python_devel.m4

What about just using one of those?

> On the other hand, we could craft our own test, using all
> python-config flags, but I would prefer to keep using provided
> autoconf macros.

Using autoconf macros or well known macros from elsewhere in preference
to rolling our own seems like a good idea to me.

> 
> >>
> >> > I would guess that python-config could produce
> >> > whatever is necessary for the platform and that the above are totally
> >> > reasonable.
> >> >
> >> > At most this should be a message which ends up in config.log but not on
> >> > stdout/err, is there a macro for that? If not I think the *) case should
> >> > just be silent.
> >> >
> >> > What do you think?
> >>
> >> Autoconf does not provide a macro to write to config.log only, but
> >> there's a little trick:
> >>
> >> http://ac-archive.sourceforge.net/doc/tricks.html
> >
> > What a strange way to provide that interface!
> >
> >> I'm going to change those messages so that they are only written to
> >> config.log but not the screen.
> >>
> >> Is the configure script working correctly under ARM? I haven't been
> >> able to get my hands on any ARM board, but I have a rpi reserved that
> >> I hope doesn't take long (I could also use Qemu I know...).
> >
> > It works fine apart from that little niggle. Or at least I haven't
> > noticed anything else.
> >
> > Ian.
> >
> >



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