Unable to link to libgfortran.a [duplicate]

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Why does the order in which libraries are linked sometimes cause errors in GCC? (9 answers)

Closed 5 years ago.

I have gfortran installed on my system and the file libgfortran.a can be found at /usr/lib/gcc/x86_64-linux-gnu/4.6/. Using nm I made sure that the function _gfortran_compare_string is defined in there:

$ nm /usr/lib/gcc/x86_64-linux-gnu/4.6/libgfortran.a | grep _gfortran_compare_string

Returns

0000000000000000 T _gfortran_compare_string
0000000000000000 T _gfortran_compare_string_char4

But, the linker of my CUDA-C program throws errors:

/usr/local/cuda-6.0/bin/nvcc --cudart static -L/usr/lib/gcc/x86_64-linux-gnu/4.6 -L/home/chung/lapack-3.5.0 -link -o  "pQP"  ./src/pQP.o   -lgfortran -llapacke -llapack -lcublas -lblas -lcurand
nvcc warning : The 'compute_10' and 'sm_10' architectures are deprecated, and may be removed in a future release.
/home/chung/lapack-3.5.0/liblapack.a(ilaenv.o): In function `ilaenv_':
ilaenv.f:(.text+0x81): undefined reference to `_gfortran_compare_string'

and later on another error, again related to libgfortran:

/home/chung/lapack-3.5.0/liblapack.a(xerbla.o): In function `xerbla_':
xerbla.f:(.text+0x49): undefined reference to `_gfortran_st_write'
xerbla.f:(.text+0x54): undefined reference to `_gfortran_string_len_trim'
xerbla.f:(.text+0x66): undefined reference to `_gfortran_transfer_character_write'
xerbla.f:(.text+0x76): undefined reference to `_gfortran_transfer_integer_write'
xerbla.f:(.text+0x7e): undefined reference to `_gfortran_st_write_done'
xerbla.f:(.text+0x87): undefined reference to `_gfortran_stop_string'

But, again using nm, I found that _gfortran_st_write, etc are defined in libgfortran.a.

Links: Complete log and source code.

Note: Lapack makes use of libgfortran. I recently installed lapack and ran all the tests and they all passed.

Answer 1

You need to change the order in which you specify static libraries to the linker. If you do something like this:

nvcc --cudart static -L/usr/lib/gcc/x86_64-linux-gnu/4.6 \
-L/home/chung/lapack-3.5.0 -link -o  "pQP"  ./src/pQP.o  \ 
-llapacke -llapack -lcublas -lblas -lcurand -lgfortran 

You should find it will work.

The underlying reason (and this is a trait of the gcc/gnu toolchain and not anything to do with nvcc) is that linking dependency lists for static libraries are parsed from left to right by the gnu linker. If you specify a static library before any library which depends on it, it will be skipped because it has no dependencies in the link list at the point in processing when it is first encountered.