[Buildroot] [PATCH next v2] package/pkg-meson: support per-package directories

[Thomas Petazzoni]

Hello Peter,

Could you provide some feedback on the below patch, so that we can move
forward with merging it ?

Thanks a lot!

Thomas

On Fri, 30 Nov 2018 11:40:03 +0100, Thomas Petazzoni wrote:
> From: Peter Seiderer <ps.report at gmx.net>
> 
> Currently, package/meson/meson.mk generates a single global
> cross-compilation.conf file, with the path to the compiler, cflags,
> ldflags, and various other details. This file is then used when
> building all meson-based packages.
> 
> This causes two problems:
> 
>  - It is not compatible with per-package directories, because with
>    per-package folders, we need to use a different compiler, and
>    possibly CFLAGS/LDFLAGS for each package.
> 
>  - It is not possible to define per package CFLAGS. Indeed, when
>    cross-compiling, meson doesn't support passing CFLAGS through the
>    environment, only the CFLAGS from cross-compilation.conf are taken
>    into account.
> 
> For this reason, this commit:
> 
>  - Introduces a per-package cross-compilation.conf, which is generated
>    by the pkg-meson infrastructure in the "configure" step right
>    before calling meson. The file is generated in $(@D)/build/, and
>    because it is generated within a given package "configure" step,
>    the compiler path is the one of this package.
> 
>  - Keeps the global cross-compilation.conf in $(HOST_DIR)/etc/meson/,
>    for the SDK use-case of Buildroot. Since we want the final and
>    global values of the compiler path, CFLAGS and LDFLAGS, generating
>    this global cross-compilation.conf is moved to a
>    TARGET_FINALIZE_HOOKS. If we were keeping this as a
>    HOST_MESON_POST_INSTALL_HOOKS, it would contain values specific to
>    the host-meson package.
> 
> For now, we don't yet support per-package CFLAGS/LDFLAGS, but having
> such per-package cross-compilation.conf is a necessary preparation to
> achieve this goal.
> 
> This commit has been tested by building all Buildroot packages that
> use meson: json-glib, systemd, enlightenment, at-spi2-core, ncmpc,
> libmpdclient and ncmpc.
> 
> Signed-off-by: Peter Seiderer <ps.report at gmx.net>
> [Thomas:
>  - add extended commit log
>  - in pkg-meson.mk, re-use variables defined in meson.mk to do the
>    replacement of CFLAGS/LDFLAGS/CXXFLAGS
>  - move the generation of the global cross-compilation.conf to a
>    TARGET_FINALIZE_HOOKS
>  - testing with per-package folders]
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> ---
> Changes since v1:
>  - Rework commit title and commit log. Indeed, we don't implement
>    per-package CFLAGS as part of this commit, contrary to what the
>    previous commit log was saying. However, having a per-package
>    cross-compilation.conf is a necessary preparation step to implement
>    per-package CFLAGS in the future.
> ---
>  package/meson/meson.mk |  4 +++-
>  package/pkg-meson.mk   | 12 +++++++++++-
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/package/meson/meson.mk b/package/meson/meson.mk
> index e1675c21b8..7d33e0f0d6 100644
> --- a/package/meson/meson.mk
> +++ b/package/meson/meson.mk
> @@ -20,6 +20,8 @@ HOST_MESON_SED_CFLAGS = $(if $(TARGET_CFLAGS),`printf '"%s"$(comma) ' $(TARGET_C
>  HOST_MESON_SED_LDFLAGS = $(if $(TARGET_LDFLAGS),`printf '"%s"$(comma) ' $(TARGET_LDFLAGS)`)
>  HOST_MESON_SED_CXXFLAGS = $(if $(TARGET_CXXFLAGS),`printf '"%s"$(comma) ' $(TARGET_CXXFLAGS)`)
>  
> +# Generate a Meson cross-compilation.conf suitable for use with the
> +# SDK
>  define HOST_MESON_INSTALL_CROSS_CONF
>  	mkdir -p $(HOST_DIR)/etc/meson
>  	sed -e "s%@TARGET_CROSS@%$(TARGET_CROSS)%g" \
> @@ -34,6 +36,6 @@ define HOST_MESON_INSTALL_CROSS_CONF
>  	    > $(HOST_DIR)/etc/meson/cross-compilation.conf  
>  endef
>  
> -HOST_MESON_POST_INSTALL_HOOKS += HOST_MESON_INSTALL_CROSS_CONF
> +TARGET_FINALIZE_HOOKS += HOST_MESON_INSTALL_CROSS_CONF
>  
>  $(eval $(host-python-package))
> diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
> index 507e686068..6c883041d0 100644
> --- a/package/pkg-meson.mk
> +++ b/package/pkg-meson.mk
> @@ -64,12 +64,22 @@ ifeq ($(4),target)
>  define $(2)_CONFIGURE_CMDS
>  	rm -rf $$($$(PKG)_SRCDIR)/build
>  	mkdir -p $$($$(PKG)_SRCDIR)/build
> +	sed -e "s%@TARGET_CROSS@%$$(TARGET_CROSS)%g" \
> +	    -e "s%@TARGET_ARCH@%$$(ARCH)%g" \
> +	    -e "s%@TARGET_CPU@%$$(GCC_TARGET_CPU)%g" \
> +	    -e "s%@TARGET_ENDIAN@%$$(call LOWERCASE,$$(BR2_ENDIAN))%g" \
> +	    -e "s%@TARGET_CFLAGS@%$$(HOST_MESON_SED_CFLAGS)%g" \
> +	    -e "s%@TARGET_LDFLAGS@%$$(HOST_MESON_SED_LDFLAGS)%g" \
> +	    -e "s%@TARGET_CXXFLAGS@%$$(HOST_MESON_SED_CXXFLAGS)%g" \
> +	    -e "s%@HOST_DIR@%$$(HOST_DIR)%g" \
> +	    package/meson/cross-compilation.conf.in \
> +	    > $$($$(PKG)_SRCDIR)/build/cross-compilation.conf
>  	PATH=$$(BR_PATH) $$($$(PKG)_CONF_ENV) $$(MESON) \
>  		--prefix=/usr \
>  		--libdir=lib \
>  		--default-library=$(if $(BR2_STATIC_LIBS),static,shared) \
>  		--buildtype=$(if $(BR2_ENABLE_DEBUG),debug,release) \
> -		--cross-file=$(HOST_DIR)/etc/meson/cross-compilation.conf \
> +		--cross-file=$$($$(PKG)_SRCDIR)/build/cross-compilation.conf \
>  		$$($$(PKG)_CONF_OPTS) \
>  		$$($$(PKG)_SRCDIR) $$($$(PKG)_SRCDIR)/build
>  endef



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