Re: [PATCH v2 1/4] build: add make macro for making file from file.in

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 14/11/2025 11:32 am, Juergen Gross wrote:
> diff --git a/Config.mk b/Config.mk
> index e1556dfbfa..d21d67945a 100644
> --- a/Config.mk
> +++ b/Config.mk
> @@ -159,6 +159,19 @@ define move-if-changed
>  	if ! cmp -s $(1) $(2); then mv -f $(1) $(2); else rm -f $(1); fi
>  endef
>  
> +PATH_FILES := Paths
> +INC_FILES := $(foreach f, $(PATH_FILES), $(XEN_ROOT)/config/$(f).mk)
> +
> +include $(INC_FILES)
> +
> +BUILD_MAKE_VARS := $(foreach f, $(PATH_FILES), $(shell awk '$$2 == ":=" { print $$1; }' $(XEN_ROOT)/config/$(f).mk.in))
> +
> +# Replace @xxx@ markers in $(1).in with $(xxx) variable contents, write to $(1)
> +define apply-build-vars
> + $(1): $(1).in
> +	sed $$(foreach v, $$(BUILD_MAKE_VARS), -e 's#@$$(v)@#$$($$(v))#g') <$$< >$$@
> +endef

Shouldn't this write to a tmp file, and use move-if-changed?  Most of
the time the markers won't have changed, and we'll want to short circuit
dependent rules.

~Andrew