I am trying to build a .so that dynamically links against lapack and blas at runtime. When building, the linker complains that it cannot find lapack and blas, but I am pointing right to them (I think). What else might I be missing?
I am on a Rocky 9 Linux system (pretty fresh install). Among other things, I have done yum install gcc-gfortran lapack-3.9.0-8.el9.x86_64 compat-libgfortran-48-4.8.5-36.5.el9.x86_64 openblas-serial lapack scalapack-common and also yum groupinstall "Development tools". Some of these were done to (successfully) get old binaries working again, but I include them in case they might be interfering now. With yum list, I don't see anything else promising to install.
In /usr/lib64/ I see (among other things):
lrwxrwxrwx. 1 root root 18 May 25 2022 liblapack.so.3.9 -> liblapack.so.3.9.0*
lrwxrwxrwx. 1 root root 19 May 25 2022 liblapacke.so.3.9 -> liblapacke.so.3.9.0*
lrwxrwxrwx. 1 root root 19 May 25 2022 liblapacke.so.3 -> liblapacke.so.3.9.0*
-rwxr-xr-x. 1 root root 7496688 May 25 2022 liblapack.so.3.9.0*
-rwxr-xr-x. 1 root root 2908088 May 25 2022 liblapacke.so.3.9.0*
lrwxrwxrwx. 1 root root 18 Jan 18 16:18 liblapack.so.3 -> liblapack.so.3.9.0*
lrwxrwxrwx. 1 root root 22 May 16 2022 libopenblas.so.0 -> libopenblas-r0.3.15.so*
lrwxrwxrwx. 1 root root 23 May 16 2022 libopenblaso.so.0 -> libopenblaso-r0.3.15.so*
-rwxr-xr-x. 1 root root 38111888 May 16 2022 libopenblas-r0.3.15.so*
-rwxr-xr-x. 1 root root 39653512 May 16 2022 libopenblaso-r0.3.15.so*
lrwxrwxrwx. 1 root root 17 May 25 2022 libcblas.so.3.9 -> libcblas.so.3.9.0*
lrwxrwxrwx. 1 root root 16 May 25 2022 libblas.so.3.9 -> libblas.so.3.9.0*
-rwxr-xr-x. 1 root root 119640 May 25 2022 libcblas.so.3.9.0*
-rwxr-xr-x. 1 root root 583120 May 25 2022 libblas.so.3.9.0*
lrwxrwxrwx. 1 root root 19 Jun 2 2022 libflexiblas.so.3 -> libflexiblas.so.3.0*
lrwxrwxrwx. 1 root root 24 Jun 2 2022 libflexiblas_mgmt.so.3 -> libflexiblas_mgmt.so.3.0*
lrwxrwxrwx. 1 root root 23 Jun 2 2022 libflexiblas_api.so.3 -> libflexiblas_api.so.3.0*
-rwxr-xr-x. 1 root root 3870704 Jun 2 2022 libflexiblas.so.3.0*
-rwxr-xr-x. 1 root root 53256 Jun 2 2022 libflexiblas_mgmt.so.3.0*
-rwxr-xr-x. 1 root root 15912 Jun 2 2022 libflexiblas_api.so.3.0*
lrwxrwxrwx. 1 root root 17 Jan 18 16:18 libcblas.so.3 -> libcblas.so.3.9.0*
lrwxrwxrwx. 1 root root 16 Jan 18 16:18 libblas.so.3 -> libblas.so.3.9.0*
In addition, whereis liblapack.so and whereis libblas.so both come up empty-handed.
Following what I see here, I have done:
gcc -Wall -fPIC -O -g -fopenmp mylib.c -c -o mylib.pic.o
gcc -shared -fopenmp mylib.pic.o -L/usr/lib64 -lblas -llapack -lm -o mylib.so
but I get
/usr/bin/ld: cannot find -lblas
/usr/bin/ld: cannot find -llapack
collect2: error: ld returned 1 exit status
I know about this, but it seems wrong that I would have to get into system directories and manually make soft links in order to use standard infrastructure. There must be a "right" solution I am missing.
Thanks for any help.
I am pointing right to them (I think).
No, you are not. You need libblas.so, which is not the same as libblas.so.3.
The libblas.so is needed to link new binaries against libblas. The libblas.so.3 is needed to run already linked binaries.
Usually the .so libraries are installed as part of libblas-devel or a similar package.