Re: [XEN PATCH v7 12/51] build: avoid building arm/arm/*/head.o twice

[Julien Grall <julien@xxxxxxx>]

Hi Anthony,

On 24/08/2021 11:49, Anthony PERARD wrote:
> head.o is been built twice, once because it is in $(ALL_OBJS) and a
> second time because it is in $(extra-y) and thus it is rebuilt when
> building "arch/arm/built_in.o".
>
> Fix this by adding a dependency of "head.o" on the directory
> "arch/arm/".
>
> Also, we should avoid building object that are in subdirectories, so
> move the declaration in there. This doesn't change anything as
> "arch/arm/built_in.o" depends on "arch/arm/$subarch/built_in.o" which
> depends on $(extra-y), so we still need to depend on
> "arch/arm/built_in.o".
head.o as to be right at the beginning of the binary. Will this still be 
guaranteed with this change?
Cheers,

> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>   xen/arch/arm/Makefile       | 7 ++++++-
>   xen/arch/arm/arm32/Makefile | 1 +
>   xen/arch/arm/arm64/Makefile | 2 ++
>   3 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 3d0af8ebc93c..cc90d9796e6e 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -64,7 +64,6 @@ obj-$(CONFIG_SBSA_VUART_CONSOLE) += vpl011.o
>   obj-y += vsmc.o
>   obj-y += vpsci.o
>   obj-y += vuart.o
> -extra-y += $(TARGET_SUBARCH)/head.o
>   
>   extra-y += xen.lds
>   
> @@ -76,6 +75,12 @@ endif
>   
>   ALL_OBJS := $(TARGET_SUBARCH)/head.o $(ALL_OBJS)
>   
> +# head.o is built by descending into the sub-directory, depends on the part of
> +# $(ALL_OBJS) that will eventually recurse into $(TARGET_SUBARCH)/ and build
> +# head.o
> +$(TARGET_SUBARCH)/head.o: $(BASEDIR)/arch/arm/built_in.o
> +$(TARGET_SUBARCH)/head.o: ;
> +
>   ifdef CONFIG_LIVEPATCH
>   all_symbols = --all-symbols
>   ifdef CONFIG_FAST_SYMBOL_LOOKUP
> diff --git a/xen/arch/arm/arm32/Makefile b/xen/arch/arm/arm32/Makefile
> index 96105d238307..3040eabce3ad 100644
> --- a/xen/arch/arm/arm32/Makefile
> +++ b/xen/arch/arm/arm32/Makefile
> @@ -11,3 +11,4 @@ obj-y += smpboot.o
>   obj-y += traps.o
>   obj-y += vfp.o
>   
> +extra-y += head.o
> diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
> index 40642ff57494..0bb284dedab2 100644
> --- a/xen/arch/arm/arm64/Makefile
> +++ b/xen/arch/arm/arm64/Makefile
> @@ -13,3 +13,5 @@ obj-y += smpboot.o
>   obj-y += traps.o
>   obj-y += vfp.o
>   obj-y += vsysreg.o
> +
> +extra-y += head.o
--
Julien Grall