[Buildroot] Newbie: configure: error: cannot run test program while cross compiling

[Ernest Williams]

Hi Yann,


Cheers,
Ernesto

On Fri, Jan 2, 2015 at 9:26 AM, Yann E. MORIN <yann.morin.1998 at free.fr>
wrote:

> Ernesto, All,
>
> [Note: it was hard to find your reply, since you used '>>>' to prefix
> your reply; '>' is usually used to quote the original message you are
> replying to, so it appears to me like this was quotation from a former
> message, not your actual reply. Just write your reply without prefixing
> it with anything, please ;-) ]
>

Okay, will do.


>
> On 2015-01-02 16:25 +0000, Williams Jr., Ernest L. spake thusly:
> [--SNIP--]
> > What you can do is force the result of the test, by passing the
> > appropriate value on the command line when calling configure, something
> > like the following:
> >
> >     HDF5_CONF_ENV = hdf5_cv_have_lfs=$(if $(BR2_LARGEFILE),yes,no)
> [--SNIP--]
> > >>>  This actually worked great :)
> > >>>  Can I continue with this technique?
>
> Yes, setting ac_cv_XXX is the way to go when the package wants to do
> run-time testing, because there is no other way this can be solved for
> cross-compilation.
>
> (Well, there is another way, but it involves rewriting that dmn
> configure.ac)
>
> > >>> Next error is the following:
> >
> > >>> checking for struct tm.tm_zone... yes
> > >>> checking for struct timezone... yes
> > >>> checking whether gettimeofday() gives timezone... configure:
> > >>> error: in
> `/home/ernesto/packages/buildroot-2014.11/buildroot-uclibc-x86_64/output/build/hdf5-1.8.14':
> > >>> configure: error: cannot run test program while cross compiling
> > >>> See `config.log' for more details
> >
> > >>> config.log does indeed reveal the variable name
> "ac_cv_func_gettimeofday"
> > >>> But what buildroot string must I use  "HDF5_CONF_ENV =
> hdf5_cv_have_lfs=$(if $(BR2_XXXX),yes,no) ?
> > >>> Looks like I may bump into more of this ?
>
> Yup, and you can find before hand without running, by looking for all
> instances of the AC_TRY_RUN macro, and see the conrresponding ac_cv_XXX
> variable.
>
> As for how to set ip, it really depends. Some you can always set to
> 'tes', some you can always set to 'no', some you must define depending
> on Builroot's configuration, and finally there might be some that you
> can't guess (e.g. if it has to deal with the kernel, for example), in
> which case you should be conservative, and assume the worst.
>
> As for gettimeofday returning timezone, I don't know what it means.
> Let's see at the code...
>
>     [...]
>     2180                 /* Check whether the function returned any value
> at all */
>     2181              if(tz.tz_minuteswest == 7777 && tz.tz_dsttime == 7)
>     2182                 exit(1);
>     2183              else exit (0);
>     [...]
>
> On glibc, the answer if 'yes' (I just tested natively).
>
> On uClibc and musl, gettimeofday is just a wtrapper aound the real syscall,
> so it returns whatever the kernel provides it... I'd say 'yes' too, but
> am not 100% sure...
>
> So, you'd write:
>
>     HDF5_CONF_ENV = hdf5_cv_have_lfs=yes \
>         hdf5_cv_gettimeofday_tz=yes \
>         hdf5_cv_szlib_can_encode=yes \                  [0]
>         hdf5_cv_vsnprintf_works=yes \
>         hdf5_cv_printf_ll=ll \
>         hdf5_cv_system_scope_threads=yes \              [1]
>         hdf5_cv_direct_io=yes \                         [2]
>         hdf5_cv_ldouble_to_integer_works=yes \          [3]
>         hdf5_cv_ulong_to_float_accurate=yes \
>         hdf5_cv_ulong_to_fp_bottom_bit_accurate=yes \
>         hdf5_cv_fp_to_ullong_accurate=yes \
>         hdf5_cv_fp_to_ullong_right_maximum=yes \
>         hdf5_cv_ldouble_to_uint_accurate=yes \
>         hdf5_cv_ullong_to_ldouble_precision=yes \
>         hdf5_cv_fp_to_integer_overflow_works=yes \
>         hdf5_cv_ldouble_to_long_special=no \
>         hdf5_cv_long_to_ldouble_special=no \
>         hdf5_cv_ldouble_to_llong_accurate=yes \
>         hdf5_cv_llong_to_ldouble_correct=yes
>
>
> [0] depends on what your recent szip package does, of course...
> [1] LT and NPTL have it
> [2] a proper answer would need a more thorough test, because
>     posix_memalign can be configured-out in uClibc. glibc and musl have
>     it, though...
> [3] that one and all the following are just insane test-cases for exotic
>     machines, the yes/no are just what the comments state ("should be yes
>     for all machines but XXX", or "should not be set except for YYY"...)
>


I added the new "HDF5_CONF_ENV"  that you mentioned above and now the
configure stage works :)
Thanks for your help.


>
> Note: there are AC_TRY_RUN calls that test compiler behaviour, just
> forget about those, I had a cursory look, and it tseems we don't care
> those failing.
>

Sounds good. :)


>
> Regards,
> Yann E. MORIN.
>
> --
>
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