Re: [Starpu-devel] hwloc detection problem when configuring starpu-svn-trunk and starpu-1.2.0rc5

[Brice Goglin <Brice.Goglin@inria.fr>]

Le 18/08/2016 05:21, Lucas M. Schnorr a écrit :
> Hello Nathalie,
>
> On 08/18/2016 01:55 AM, Nathalie Furmento wrote:
>> Ok, it seems that hwloc has been compiled with OpenCL. Here the error
>> when configure checks the availability of the hwloc library.
>>
>> configure:35295: /home/lschnorr/spack-orion/lib/spack/env/gcc/gcc -o
>> conftest -O3 -g -O2 -gdwarf-2 -g3    -D_GNU_SOURCE 
>> -I/home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/include
>>  
>> -gdwarf-2 -g3 
>> -L/home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib
>> conftest.c -lhwloc  -lrt -lm -lpthread  >&5
>> /home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib/libhwloc.so:
>> undefined reference to `clGetPlatformIDs@OPENCL_1.0'
>> /home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib/libhwloc.so:
>> undefined reference to `clGetDeviceIDs@OPENCL_1.0'
>> /home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib/libhwloc.so:
>> undefined reference to `clGetPlatformInfo@OPENCL_1.0'
>> /home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib/libhwloc.so:
>> undefined reference to `clGetDeviceInfo@OPENCL_1.0'
>>
>> The dirty fix would be to modify configure.ac and add the proper -l
>> and -L options for OpenCL. Or better, set LDFLAGS with the
>> appropriate value.
>>
>> A better way would be to use pkgconfig to get the correct flags to
>> use when compiling/linking with hwloc. Could you please send me the
>> contents of the file
>> /home/lschnorr/spack-orion/opt/spack/linux-x86_64/gcc-6.1.0/hwloc-1.11.3-j3wlufl4afo5kvid3vv4rutn55ljz2nx/lib/pkgconfig/hwloc.pc
>>
>
> Sure, here it goes (hwloc.pc).
>
> Let me know (on which version/trunk) when it is done so I can test again.

Hello

You're not supposed to add -lOpenCL since it's private to hwloc, your
program does not use OpenCL directly. Just linking with -lhwloc should
be enough as long as the linker finds the OpenCL library in the back
(same for libnuma).

So the question is whether your linker didn't auto-add libOpenCL.so
(why? "objdump -x /path/to/libhwloc.so | grep NEEDED" should show
libOpenCL.so, and "ldd /path/to/libhwloc.so" should find libOpenCL too)
or whether it tries to add it but failed to find libOpenCL.so (it is
installed in a standard directory? need LIBRARY_PATH and LD_LIBRARY_PATH?).

I get the same errors when I move libOpenCL to another location, but ld
first complains "libOpenCL.so.1, needed by libhwloc.so, not found". Your
linker did not complain the same.

Brice