[Buildroot] [PATCH v2] package/armadillo: allows to select between clapack, lapack or openblas

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Mon, 24 Aug 2020 15:22:15 +0200
Gwenhael Goavec-Merou <gwenj@trabucayre.com> wrote:

> diff --git a/package/armadillo/Config.in b/package/armadillo/Config.in
> index b2b61a3233..0a65f5b966 100644
> --- a/package/armadillo/Config.in
> +++ b/package/armadillo/Config.in
> @@ -1,3 +1,12 @@
> +config BR2_PACKAGE_ARMADILLO_CLAPACK_SUPPORTS
> +	bool
> +	default y if (!BR2_m68k_cf && (!BR2_powerpc || BR2_TOOLCHAIN_USES_GLIBC))

Can we write this like this:

	default y
	depends on !BR2_m68k
	depends on !BR2_powerpc || BR2_TOOLCHAIN_USES_GLIBC

> +config BR2_PACKAGE_ARMADILLO_LAPACK_SUPPORTS
> +	bool
> +	default y if BR2_TOOLCHAIN_HAS_FORTRAN && \
> +		BR2_PACKAGE_OPENBLAS_ARCH_SUPPORTS

I am a bit confused here, why does it require
BR2_PACKAGE_OPENBLAS_ARCH_SUPPORTS ? What is the relationship between
lapack support and openblas ?

Also, the lapack package has a "depends on !CLAPACK" so if the user has
clapack enabled, it should not be possible to enable the lapack "usage"
in armadillo.

Also, don't you need to take into account the following dependency from
lapack:

        # _fpu_control is used on PowerPC, but not available with uClibc
        depends on !(BR2_powerpc && BR2_TOOLCHAIN_USES_UCLIBC)

> +
>  comment "armadillo needs a toolchain w/ C++"
>  	depends on !BR2_INSTALL_LIBSTDCPP
>  	depends on !BR2_powerpc
> @@ -10,11 +19,46 @@ comment "armadillo needs a glibc toolchain w/ C++"
>  config BR2_PACKAGE_ARMADILLO
>  	bool "armadillo"
>  	depends on BR2_INSTALL_LIBSTDCPP
> -	depends on !BR2_powerpc || BR2_TOOLCHAIN_USES_GLIBC # clapack
> -	depends on !BR2_m68k_cf # clapack
> -	select BR2_PACKAGE_CLAPACK
> +	depends on BR2_PACKAGE_ARMADILLO_CLAPACK_SUPPORTS || \
> +		BR2_PACKAGE_ARMADILLO_LAPACK_SUPPORTS || \
> +		BR2_PACKAGE_OPENBLAS_ARCH_SUPPORTS
>  	help
>  	  Armadillo: An Open Source C++ Linear Algebra Library for
>  	  Fast Prototyping and Computationally Intensive Experiments.
>  
>  	  http://arma.sourceforge.net/
> +
> +if BR2_PACKAGE_ARMADILLO
> +
> +choice

Do we really need this choice ? Isn't it possible in the .mk to prefer
one solution if available, then another, and finally another ?

This is really an open question: if there are good reason to showing
this choice to the user, we can keep it.

> +	prompt "blas library"
> +	default BR2_PACKAGE_ARMADILLO_CLAPACK if \
> +		BR2_PACKAGE_ARMADILLO_CLAPACK_SUPPORTS
> +	default BR2_PACKAGE_ARMADILLO_LAPACK if \
> +		BR2_PACKAGE_ARMADILLO_LAPACK_SUPPORTS && \
> +		!BR2_PACKAGE_ARMADILLO_CLAPACK_SUPPORTS

I think you can drop the !BR2_PACKAGE_ARMADILLO_CLAPACK_SUPPORTS,
Kconfig will pickup the first "default" that has its dependencies met.
In fact, you could simply drop all those default statements, and
Kconfig would pick the first choice entry that has its dependencies met.

> diff --git a/package/armadillo/armadillo.mk b/package/armadillo/armadillo.mk
> index 624b842ef6..1cc3d0c968 100644
> --- a/package/armadillo/armadillo.mk
> +++ b/package/armadillo/armadillo.mk
> @@ -7,11 +7,20 @@
>  ARMADILLO_VERSION = 9.900.2
>  ARMADILLO_SOURCE = armadillo-$(ARMADILLO_VERSION).tar.xz
>  ARMADILLO_SITE = https://downloads.sourceforge.net/project/arma
> -ARMADILLO_DEPENDENCIES = clapack
>  ARMADILLO_INSTALL_STAGING = YES
>  ARMADILLO_LICENSE = Apache-2.0
>  ARMADILLO_LICENSE_FILES = LICENSE.txt
>  
> +ifeq ($(BR2_PACKAGE_ARMADILLO_OPENBLAS),y)
> +ARMADILLO_DEPENDENCIES = openblas
> +else
> +ifeq ($(BR2_PACKAGE_ARMADILLO_CLAPACK), y)

put the "else" and following "ifeq" on the same line, so that you don't
need an additional "endif".

I.e:

ifeq ...
...
else ifeq ...
...
else
...
endif

> +ARMADILLO_DEPENDENCIES = clapack
> +else
> +ARMADILLO_DEPENDENCIES = lapack
> +endif
> +endif

With this logic, there is in fact nothing that guarantees which blas
library will be used. If both openblas and clapack are available on the
system, even if you select BR2_PACKAGE_ARMADILLO_CLAPACK, openblas
might be used by armadillo...

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com