Build break on SPU (and other non-mmap systems?) (Re: [patch,libgfortran,toplevel] Use libbacktrace in libgfortran)

[Jeff Law]

On 08/24/2015 06:55 AM, Ulrich Weigand wrote:
> FX Coudert wrote:
>
>> The idea is that libbacktrace should be able to build on all targets, at
>> least in a minimally-functional form:
>> https://gcc.gnu.org/ml/gcc/2015-08/msg00038.html
>> libgfortran should continue to build on all targets, even those that
>> don't have an mmap().
>>
>> I see that there is a test in libbacktrace/configure.ac for mmap(), but
>> apparently it fails on your system:
>
> Ah, I see.  On the SPU, we do have an sys/mman.h header file, which provides
> a "mmap_eaddr" routine used to map files into the DMA address space, and
> associated mmap flags.  That's why the test gets confused.
>
>> So this should be the place to patch things up. Relying on the presence of
>> <sys/mman.h> is apparently not restrictive enough. Maybe we could use a
>> AC_EGREP_HEADER test, as is currently done for dl_interate_phdr()?
>
> Hmm, that seems tricky, since the SPU sys/mman.h file contains the prototype
> for mmap_eaddr, and the string "mmap" in various comments ...
>
> I guess we can always just hard-code that SPU does not have mmap, similar
> to how Solaris is hard-coded to not have dl_iterate_phdr.
>
> Would something like the below be OK (if it passes testing)?
Yes.

Jeff