undefined reference to `__offload_target_acquire' and `__offload_offload'

[Chris_N_]

The following program compiles fine and runs on the MIC:

#include <stdlib.h>
#include <stdio.h>
main() {
float micret=1.001;
int mici;
#pragma offload target (mic:0) inout(micret, mici)
for(mici=0;mici<=1000; mici++){
micret*=1.001;
}
fprintf(stderr,"FOUND %g\n",micret);
}

## output from the executable (subsequent to "export OFFLOAD_REPORT=2") is:

[Offload] [MIC 0] [File] prog.c
[Offload] [MIC 0] [Line] 9
[Offload] [MIC 0] [Tag] Tag0
[Offload] [MIC 0] [CPU Time] 0.000000 (seconds)
[Offload] [MIC 0] [CPU->MIC Data] 8 (bytes)
[Offload] [MIC 0] [MIC Time] 0.000100 (seconds)
[Offload] [MIC 0] [MIC->CPU Data] 8 (bytes)

FOUND 2.72235

However, when I try to add that code into the body of a function in a large executable, I get the following errors:

undefined reference to `__offload_target_acquire'
undefined reference to `__offload_offload'

While the small test program was compiled with icc directly, for the large program I am using cmake; make.

Can anybody suggest why I am getting these errors?

Thank you, Chris.

[Chris_N_]

I should clarify that those errors were obtained during compilation and I was unable to obtain a working executable.

[Frances_R_Intel]

When you compiled your small test case, you ran the compilervars script. I'm not sure how your makefile is written, and I am certainly no expert on cmake, but you need to make sure the LD_LIBRARY_PATH and MIC_LD_LIBRARY_PATH variables are getting properly set. The routines you are missing in this case are in /opt/intel/composerxe/lib/intel64. 

[Chris_N_]

Thank you very much Frances.

Turns out that I can avoid the errors and get it to compile when I omit the gromacs compilation cmake flag -DGMX_PREFER_STATIC_LIBS=ON

Without knowing exactly what that does in the gromacs cmake call, does it make sense that a mic offload doesn't work with static libraries? If not, then I guess that I should look into the routines that you mention.

Thank you,

Chris.

[Frances_R_Intel]

The libraries you need exist as .so but not as .a files. If I understand what I read when I searched for GMX_PREFER_STATIC_LIBS on the web, cmake should have gone ahead and used the .so files when it couldn't find any .a files. So I really don't know why it had trouble. Sorry.

[Chris_N_]

Thank you Frances, this will be useful information once we get the offloading done and want to reenable the GMX_PREFER_STATIC_LIBS setting for use with CPU+MIC.

[Chris_N_]

Thank you Frances, this will be useful information once we get the offloading done and want to reenable the GMX_PREFER_STATIC_LIBS setting for use with CPU+MIC.