Re: [Xen-devel] [RFC v2] xen/arm: build: add missed dependency for head.S

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Jun 07, 2016 at 12:34:43PM +0800, Wei Chen wrote:
> In current Xen build rules, the build system will only check the
> dependencies in current folder and obj-y generated dependencies
> in other folder.
> 
> But Makefile may add some objects to ALL_OBJS. These objects may
> be not in the same folder as Makefile. Use arch/arm/Makefile as
> an example:
>     ALL_OBJS := $(TARGET_SUBARCH)/head.o
> 
> The head.o is not in the same folder as Makefile and is not listed
> in obj-y. So, when we update the header files that had been included
> in head.S. The build system would not check the dependency of head.S.
> The head.S would not be re-compiled.
> 
> In this patch, we will get objects added by Makefile and add their
> dependencies to check list.
> 
> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxxxxx>
> ---
> v1 -> v2:
> - Use a generic method instead of changing Makefiles
> ---
>  xen/Rules.mk | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/Rules.mk b/xen/Rules.mk
> index 961d533..fb3087c 100644
> --- a/xen/Rules.mk
> +++ b/xen/Rules.mk
> @@ -95,12 +95,21 @@ include $(BASEDIR)/arch/$(TARGET_ARCH)/Rules.mk
>  include Makefile
>  
>  DEPS = .*.d
> +
> +# In obj-y and ALL_OBJS, there may have some objects are not in the

You are missing a verb here.

I think you mean to say 'there may be some objects which are not in the'
> +# same folder as Makefile, so we have to use gendep to generate
> +# dependencies for them.
> +DEP_OBJS = $(obj-y)
> +
> +# Extract objects from ALL_OBJS added by Makefile.
> +DEP_OBJS += $(filter-out %built_in.o,$(ALL_OBJS))
> +
>  define gendep
>      ifneq ($(1),$(subst /,:,$(1)))
>          DEPS += $(dir $(1)).$(notdir $(1)).d
>      endif
>  endef
> -$(foreach o,$(filter-out %/,$(obj-y)),$(eval $(call gendep,$(o))))
> +$(foreach o,$(filter-out %/,$(DEP_OBJS)),$(eval $(call gendep,$(o))))
>  
>  # Ensure each subdirectory has exactly one trailing slash.
>  subdir-n := $(patsubst %,%/,$(patsubst %/,%,$(subdir-n) $(subdir-)))
> -- 
> 2.7.4
> 
> 
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