Hello. What is the difference between (LoadLibrary "") and (loadExecutable ()) calls?
2018-09-10 17:53 GMT+03:00 Phil Clayton <phil.clayton at veonix.com>:
Slight correction: using an empty string for the library has the effect of passing NULL to dlopen which means the handle passed to dlsym is the current program.
On 10/09/18 15:29, Phil Clayton wrote:
Hi Mark,
(* symbol lookup error: /usr/lib/x86_64-linux-gnu/libgsl.so: undefined symbol: cblas_dgemm *)
To avoid looking for the symbol "cblas_dgemm" in libgsl (which doesn't define it), you could let the dynamic linker look for it by using an empty string for the library which has the effect of passing RTLD_DEFAULT to dlsym.
val gsl = loadLibrary "";
To make sure these libraries are searched, you would need to start your poly session with something like
LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libgsl.so":"/usr/lib/x86_64-linux-gnu/libgslcblas.so \ poly
which could be put into a wrapper script. Or you could build an executable (which could be a poly REPL) and link to them.
Another advantage of this approach is portability. The SML code is more portable because shared object names and their paths vary across systems. Linking also avoids the problem of specifying the library names because you use flags such as -lgsl and the linker works it out. Linking can be done in an even more portable way using a utility like pkg-config to generate the linker arguments:
pkg-config --libs gsl
(This usual requires the -devel or -dev package for the library.)
Regards, Phil
On 09/09/18 21:15, Mark Clements wrote:
I am enjoying using polyml's Foreign structure.
However, in using the GNU Scientific Library (GSL), I have run into a problem with linkage. The GSL library (libgsl.so) calls standard cBLAS matrix functions with unknown symbols to allow the user to link with different cBLAS implementations (NB: GSL provides an unoptimised cBLAS implementation named libgslcblas.so). When I call a GSL function that depends on the cBLAS functions, I get a symbol not defined error.
I have tried unsuccessfully (a) loading the libgslcblas library either before or after loading libgsl, (b) changing the loadLibrary implementation to use dlopen with RTLD_LAZY | RTLD_GLOBAL, and (c) compiling the SML code to an object file and then linking against the libraries.
How could this be made to work?
Sincerely, Mark.
PS test code for (a) is:
open Foreign; val gsl = loadLibrary "/usr/lib/x86_64-linux-gnu/libgsl.so"; val gslcblas = loadLibrary "/usr/lib/x86_64-linux-gnu/libgslcblas.so"; type gsl_matrix_t = Memory.voidStar; (* for demonstration only *) local val call1 = buildCall2((getSymbol gsl "gsl_matrix_calloc"), (cInt,cInt), cPointer) val call2 = buildCall4((getSymbol gsl "gsl_matrix_set"), (cPointer,cInt,cInt,cDouble), cVoid) val call3 = buildCall3((getSymbol gsl "gsl_linalg_exponential_ss"), (cPointer, cPointer, cDouble), cVoid) in fun gsl_matrix_alloc (size1,size2) = call1(size1,size2) fun gsl_matrix_set (ptr : gsl_matrix_t, i, j, x) = call2(ptr, i, j, x) fun gsl_matrix (arr : real Array2.array) = let val size1 = Array2.nRows arr val size2 = Array2.nCols arr val ptr = gsl_matrix_alloc(size1, size2) val _ = Array2.tabulate Array2.RowMajor (size1, size2, fn (i,j) => gsl_matrix_set(ptr, i, j, Array2.sub(arr, i, j))) in ptr end fun gsl_mexp (arr : real Array2.array) = let val size1 = Array2.nRows arr val size2 = Array2.nCols arr val ptr = gsl_matrix arr val ptr2 = gsl_matrix_alloc(size1, size2) val _ = call3(ptr, ptr2, 0.01) in ptr2 end end; fun main() = let val a = Array2.fromList [[1.0,2.0],[3.0,4.0]]; val ptr = gsl_matrix(a); val m = gsl_mexp(a) (* fails *) in () end; (* symbol lookup error: /usr/lib/x86_64-linux-gnu/libgsl.so: undefined symbol: cblas_dgemm *)
For (c):
polyc -c test.sml g++ test.o -L/usr/lib/x86_64-linux-gnu -lgsl -lgslcblas `pkg-config --libs polyml` ./a.out # same error _______________________________________________ polyml mailing list polyml at inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml
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