linux-kernel - Re: [PATCH] kbuild, x86: drop unnecessary prefix map configuration

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Message-ID: <CAK7LNATEn2n9Brt6oKnywuUh_Hyu8xhsW04fdp=3yevpwXY5=g@mail.gmail.com>
Date: Sat, 22 Mar 2025 23:13:39 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Nicolas Schier <nicolas@...sle.eu>, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>, 
	Ben Hutchings <ben@...adent.org.uk>
Subject: Re: [PATCH] kbuild, x86: drop unnecessary prefix map configuration

On Sat, Mar 22, 2025 at 6:03 PM Thomas Weißschuh <linux@...ssschuh.net> wrote:
>
> The toplevel Makefile already provides -ffile-prefix-map as part of

I replaced -ffile-prefix-map with -fmacro-prefix-map

> KBUILD_CPPFLAGS. In contrast to the KBUILD_CFLAGS and KBUILD_AFLAGS
> variables, KBUILD_CPPFLAGS is not redefined in the architecture specific
> Makefiles. Therefore the toplevel KBUILD_CPPFLAGS do apply just fine, to
> both C and ASM sources.
>
> The custom configuration was necessary when it was added in
> commit 9e2276fa6eb3 ("arch/x86/boot: Use prefix map to avoid embedded paths")
> but has since become unnecessary in
> commit a716bd743210 ("kbuild: use -fmacro-prefix-map for .S sources")
>
> Drop the now unnecessary custom prefix map configuration.
>
> Link: https://lore.kernel.org/lkml/d250e864d6d81cc02e2599f710872f72d58a3c29.camel@decadent.org.uk/
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
> Intended to go through the kbuild tree.
>
> It would have been nice to have this before
> "kbuild: make all file references relative to source root",
> but I guess it's really not worth a rebase and the complexity.

OK, I inserted this before the previous patch.
Thanks.





> ---
>  arch/x86/boot/Makefile            | 1 -
>  arch/x86/boot/compressed/Makefile | 1 -
>  2 files changed, 2 deletions(-)
>
> diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
> index f500f82864aae80deb74faa3df9a8b6333d6c4ca..75e7a76deee1541ffed05953eb0574f14fe193a9 100644
> --- a/arch/x86/boot/Makefile
> +++ b/arch/x86/boot/Makefile
> @@ -54,7 +54,6 @@ targets += cpustr.h
>
>  KBUILD_CFLAGS  := $(REALMODE_CFLAGS) -D_SETUP
>  KBUILD_AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
> -KBUILD_CFLAGS  += $(call cc-option,-ffile-prefix-map=$(srctree)/=)
>  KBUILD_CFLAGS  += -fno-asynchronous-unwind-tables
>  KBUILD_CFLAGS  += $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index ad324978b2e5b1b6f8be82647769c99db8257ac7..4d3f714ad8717db2235a707269d26565a9671187 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -38,7 +38,6 @@ KBUILD_CFLAGS += -fno-stack-protector
>  KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
>  KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
>  KBUILD_CFLAGS += -Wno-pointer-sign
> -KBUILD_CFLAGS += $(call cc-option,-ffile-prefix-map=$(srctree)/=)
>  KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
>  KBUILD_CFLAGS += -D__DISABLE_EXPORTS
>  # Disable relocation relaxation in case the link is not PIE.
>
> ---
> base-commit: 1a78774bb35068bb143d2299da3f8a0b87807cdb
> change-id: 20250322-asm-prefix-map-028f044d87b3
>
> Best regards,
> --
> Thomas Weißschuh <linux@...ssschuh.net>
>


--
Best Regards
Masahiro Yamada