Re: [XEN PATCH v5 03/16] xen/build: use new $(c_flags) and $(a_flags) instead of $(CFLAGS)

From: Julien Grall <julien@xen.org>
To: Anthony PERARD <anthony.perard@citrix.com>,
	xen-devel@lists.xenproject.org
Cc: "Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wl@xen.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Ian Jackson" <ian.jackson@eu.citrix.com>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Tim Deegan" <tim@xen.org>, "Jan Beulich" <jbeulich@suse.com>,
	"Volodymyr Babchuk" <Volodymyr_Babchuk@epam.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [XEN PATCH v5 03/16] xen/build: use new $(c_flags) and $(a_flags) instead of $(CFLAGS)
Date: Fri, 24 Apr 2020 10:20:17 +0100	[thread overview]
Message-ID: <91b44d25-a10e-fdd2-2fbc-84f5ae3e5a36@xen.org> (raw)
In-Reply-To: <20200421161208.2429539-4-anthony.perard@citrix.com>

Hi,

On 21/04/2020 17:11, Anthony PERARD wrote:
> In a later patch ("xen/build: have the root Makefile generates the
> CFLAGS), we want to generate the CFLAGS in xen/Makefile, then export
> it and have Rules.mk use a CFLAGS from the environment variables. That
> changes the flavor of the CFLAGS and flags intended for one target
> (like -D__OBJECT_FILE__ and -M%) gets propagated and duplicated. So we
> start by moving such flags out of $(CFLAGS) and into $(c_flags) which
> is to be modified by only Rules.mk.
> 
> __OBJECT_FILE__ is only used by arch/x86/mm/*.c files, so having it in
> $(c_flags) is enough, we don't need it in $(a_flags).
> 
> For include/Makefile and as-insn we can keep using CFLAGS, but since
> it doesn't have -M* flags anymore there is no need to filter them out.
> 
> The XEN_BUILD_EFI tests in arch/x86/Makefile was filtering out
> CFLAGS-y, but according to dd40177c1bc8 ("x86-64/EFI: add CFLAGS to
> check compile"), it was done to filter out -MF. CFLAGS doesn't
> have those flags anymore, so no filtering is needed.
> 
> This is inspired by the way Kbuild generates CFLAGS for each targets.
> 
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>

For the Arm bits:

Acked-by: Julien Grall <jgrall@amazon.com>

Cheers,

-- 
Julien Grall