R build BLAS/LAPACK debugging ('dgemmtr_' undefined)
Possibly related, ever since that change to R, I found I have to build OpenBLAS *with* Lapack because of the change in where OpenBLAS "stores" some functions. See issue 4684 in the OpenBLAS Github repo [1]. As a result, you will see a much larger .a file. However, the processor-named and unnamed (just libopenblas.a) should now be the same after 4692 [2]. Either one works, at least for me, Hope that helps, Avi [1] https://github.com/OpenMathLib/OpenBLAS/issues/4684 [2] https://github.com/OpenMathLib/OpenBLAS/discussions/4692
On Mon, Jan 26, 2026 at 12:45?PM Ben Bolker <bbolker at gmail.com> wrote:
I'm sure I'm doing something dumb, but having trouble building R from source on PopOS! 22.04 LTS (debian/Ubuntu 'jammy' derivative): "undefined symbol: dgemmtr_" when trying to load stuff from LAPACK. R appears to find stuff at the configure step (FWIW I get the same error below if I take out "with-blas=-lopenblas") $ ../r-devel/configure --enable-R-shlib --enable-memory-profiling --with-blas=-lopenblas | grep blas configure: WARNING: C23 support is unavailable checking for dgemm_ in -lopenblas... yes config.status: creating src/extra/blas/Makefile Then `make` fails with: byte-compiling package 'grDevices' Warning in solve.default(rgb) : unable to load shared object '/home/bolker/R/r-build/modules//lapack.so': /home/bolker/R/r-build/lib/libRlapack.so: undefined symbol: dgemmtr_ Error in solve.default(rgb) : LAPACK routines cannot be loaded I do see a NEWS item from R 4.5.0 https://github.com/r-devel/r-svn/blob/42e81d981a540f4afc01d1002a64ab347eb5dc15/doc/NEWS.Rd#L956-L961 (I thought things were working until recently, but I haven't re-built from scratch in a while ...) \item This update was mainly bug fixes but contained a barely documented major change. The set of BLAS routines had been unchanged since 1988, so throughout \R's history. This update introduced new BLAS routines \code{dgemmtr} and \code{zgemmtr} which are now used by LAPACK routines. This means that BLAS implementations are no longer interchangeable. Section A.3.1 https://rstudio.github.io/r-manuals/r-admin/Essential-and-useful-other-programs-under-a-Unix-alike.html:
> The configure code checks that the external BLAS is complete (as of
LAPACK 3.9.1: it must include all double precision and double complex
routines, as well as LSAME), and appears to be usable. However, an
external BLAS has to be usable from a shared object (so must contain
position-independent code), and that is not checked.
I'd be surprised if by BLAS libraries *didn't* contain PIC, but ... ??
Suggestions for diagnostics/debugging welcome ...
cheers
Ben Bolker
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