Re: [XEN PATCH v4 07/18] build: Introduce documentation for xen Makefiles

[Jan Beulich <jbeulich@xxxxxxxx>]

On 31.03.2020 12:30, Anthony PERARD wrote:
> This start explainning the variables that can be used in the many
> Makefiles in xen/.
> 
> Most of the document copies and modifies text from Linux v5.4 document
> linux.git/Documentation/kbuild/makefiles.rst. Modification are mostly
> to avoid mentioning kbuild. Thus I've added the SPDX tag which was
> only in index.rst in linux.git.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
with one question:

> +Compilation flags
> +-----------------
> +
> +    CFLAGS-y and AFLAGS-y
> +     These two flags apply only to the makefile in which they
> +     are assigned. They are used for all the normal cc, as and ld
> +     invocations happening during a recursive build.
> +
> +     $(CFLAGS-y) is necessary because the top Makefile owns the
> +     variable $(XEN_CFLAGS) and uses it for compilation flags for the
> +     entire tree. And the variable $(CFLAGS) is modified by Config.mk
> +     which evaluated in every subdirs.
> +
> +     CFLAGS-y specifies options for compiling with $(CC).
> +     AFLAGS-y specifies assembler options.

Is it perhaps worth mentioning that c_flags and a_flags should
not be fiddled with by individual Makefile-s?

Jan