R SIG Debian - Dec 2023 - custom built R will not change BLAS/LAPACK with update-alternatives

On Sat, 30 Dec 2023 18:37:06 +0100
Ramon Diaz-Uriarte <rdiaz02 at gmail.com> wrote:
>  configure: searching for an external BLAS
> configure: searching for BLAS in default libraries
> checking for dgemm_... no
> configure: searching for OpenBLAS
The code implementing this logic is in m4/R.m4, starting around line
2600. If --with-blas is given without an argument, the configure script
goes searching for various BLASes. It happens to try -lopenblas before
-lblas, so that's what ends up being linked.

Does it help to use --with-blas=blas or --with-blas=-lblas so that the
configure script doesn't try to detect it automatically?

-- 
Best regards,
Ivan

On 30 December 2023 at 21:57, Ivan Krylov wrote:
| On Sat, 30 Dec 2023 18:37:06 +0100
| Ramon Diaz-Uriarte <rdiaz02 at gmail.com> wrote:
| 
| >  configure: searching for an external BLAS
| > configure: searching for BLAS in default libraries
| > checking for dgemm_... no
| > configure: searching for OpenBLAS
| 
| The code implementing this logic is in m4/R.m4, starting around line
| 2600. If --with-blas is given without an argument, the configure script
| goes searching for various BLASes. It happens to try -lopenblas before
| -lblas, so that's what ends up being linked.

Yes. My hint about the build-dependencies aimed at that.
 
| Does it help to use --with-blas=blas or --with-blas=-lblas so that the
| configure script doesn't try to detect it automatically?

I used to set it that way (still commented out in debian/rules) but it is not
needed AFAICT provided one has suitable packages to build against installed
(in the chroot, or container, or on the machine).

Dirk

-- 
dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org

On Sat, 30-December-2023, at 19:57:10, Ivan Krylov <krylov.r00t at
gmail.com> wrote:
> On Sat, 30 Dec 2023 18:37:06 +0100
> Ramon Diaz-Uriarte <rdiaz02 at gmail.com> wrote:
>
>>  configure: searching for an external BLAS
>> configure: searching for BLAS in default libraries
>> checking for dgemm_... no
>> configure: searching for OpenBLAS
>
> The code implementing this logic is in m4/R.m4, starting around line
> 2600. If --with-blas is given without an argument, the configure script
> goes searching for various BLASes. It happens to try -lopenblas before
> -lblas, so that's what ends up being linked.
>
Thanks. Yes, I just realized that (see message I just sent).
> Does it help to use --with-blas=blas or --with-blas=-lblas so that the
> configure script doesn't try to detect it automatically?
Yes, it does: if I use

--with-blas="-lblas"
--with-lapack="-llapack"

then I can later change the library used via update-alternatives.

R.


-- 
Ramon Diaz-Uriarte
Department of Biochemistry, Lab B-31
Facultad de Medicina 
Universidad Aut?noma de Madrid 
Arzobispo Morcillo, 4
28029 Madrid
Spain

Phone: +34-91-497-2412

Email: rdiaz02 at gmail.com
       r.diaz at uam.es
       ramon.diaz at iib.uam.es

https://ligarto.org/rdiaz