[Buildroot] [PATCH 1/3] package/pkg-golang: add support for host target

[Thomas Petazzoni]

Hello Mirza,

On Sun, 26 Aug 2018 23:41:44 +0200, Mirza Krak wrote:
> With this you can add:
> 
>     $(eval $(host-golang-package))
> 
> to a package .mk file to build for host.
> 
> Signed-off-by: Mirza Krak <mirza.krak at northern.tech>

Thanks for this contribution! I believe the title should be improved,
because "host target" is a bit confusion. Perhaps:

package/pkg-golang: add support for building host packages

This commit also needs a small update to the Buildroot manual, to add
something like "The ability to build host packages is also available,
with the host-golang-package macro."

> ---
>  package/pkg-golang.mk | 38 +++++++++++++++++++++++++++++++++-----
>  1 file changed, 33 insertions(+), 5 deletions(-)
> 
> diff --git a/package/pkg-golang.mk b/package/pkg-golang.mk
> index 6eacd14180..7d9956378f 100644
> --- a/package/pkg-golang.mk
> +++ b/package/pkg-golang.mk
> @@ -23,10 +23,13 @@
>  
>  GO_BIN = $(HOST_DIR)/bin/go
>  
> -# We pass an empty GOBIN, otherwise "go install: cannot install
> -# cross-compiled binaries when GOBIN is set"
>  GO_TARGET_ENV = \
>  	$(HOST_GO_TARGET_ENV) \
> +	$(GO_HOST_ENV)

I think it's a bit weird and dangerous to re-use GO_HOST_ENV in
GO_TARGET_ENV. Indeed, there is the risk that we add something
host-specific, and it will be re-used for both target and host.

So either your duplicate the definitions (which is reasonable if they
aren't a lot of them), or you add something like GO_COMMON_ENV, re-used
between target and host.

>  define inner-golang-package
> @@ -96,6 +98,9 @@ endif
>  # Build step. Only define it if not already defined by the package .mk
>  # file.
>  ifndef $(2)_BUILD_CMDS
> +ifeq ($(4),target)
> +

Drop this empty line.

> +# Build package for target
>  define $(2)_BUILD_CMDS
>  	$$(foreach d,$$($(2)_BUILD_TARGETS),\
>  		cd $$($(2)_SRC_PATH); \
> @@ -107,10 +112,23 @@ define $(2)_BUILD_CMDS
>  			./$$(d)
>  	)
>  endef
> +else
> +	# Build package for host

Don't indent this comment.

> +define $(2)_BUILD_CMDS
> +	$$(foreach d,$$($(2)_BUILD_TARGETS),\
> +		cd $$($(2)_SRC_PATH); \
> +		$$(GO_HOST_ENV) \
> +			GOPATH="$$(@D)/$$($(2)_WORKSPACE)" \
> +			$$($(2)_GO_ENV) \
> +			$$(GO_BIN) build -v $$($(2)_BUILD_OPTS) \
> +			-o $$(@D)/bin/$$(or $$($(2)_BIN_NAME),$$(notdir $$(d))) \
> +			./$$(d)
> +	)
> +endef
> +endif
>  endif
>  
> -# Target installation step. Only define it if not already defined by the
> -# package .mk file.

Why are you changing this comment ?

> +# Target installation step
>  ifndef $(2)_INSTALL_TARGET_CMDS
>  define $(2)_INSTALL_TARGET_CMDS
>  	$$(foreach d,$$($(2)_INSTALL_BINS),\
> @@ -119,6 +137,15 @@ define $(2)_INSTALL_TARGET_CMDS
>  endef
>  endif
>  
> +# Host installation step
> +ifndef $(2)_INSTALL_CMDS
> +define $(2)_INSTALL_CMDS
> +	$$(foreach d,$$($(2)_INSTALL_BINS),\
> +		$(INSTALL) -D -m 0755 $$(@D)/bin/$$(d) $(HOST_DIR)/usr/bin/$$(d)


Install in $(HOST_DIR)/bin, not $(HOST_DIR)/usr/bin. We no longer use
$(HOST_DIR)/usr/bin in fact, and $(HOST_DIR)/usr is a symlink to
$(HOST_DIR).

Thanks!

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