FAILED: patch "[PATCH] kbuild: hdrcheck: fix cross build with clang" failed to apply to 5.4-stable tree

FAILED: patch "[PATCH] kbuild: hdrcheck: fix cross build with clang" failed to apply to 5.4-stable tree

[gregkh]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 02e9a22ceef0227175e391902d8760425fa072c6
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025061706-stylishly-ravioli-ffa1@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 02e9a22ceef0227175e391902d8760425fa072c6 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Tue, 25 Feb 2025 11:00:31 +0100
Subject: [PATCH] kbuild: hdrcheck: fix cross build with clang

The headercheck tries to call clang with a mix of compiler arguments
that don't include the target architecture. When building e.g. x86
headers on arm64, this produces a warning like

   clang: warning: unknown platform, assuming -mfloat-abi=soft

Add in the KBUILD_CPPFLAGS, which contain the target, in order to make it
build properly.

See also 1b71c2fb04e7 ("kbuild: userprogs: fix bitsize and target
detection on clang").

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/usr/include/Makefile b/usr/include/Makefile
index 6c6de1b1622b..e3d6b03527fe 100644
--- a/usr/include/Makefile
+++ b/usr/include/Makefile
@@ -10,7 +10,7 @@ UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration
 
 # In theory, we do not care -m32 or -m64 for header compile tests.
 # It is here just because CONFIG_CC_CAN_LINK is tested with -m32 or -m64.
-UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
+UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
 
 # USERCFLAGS might contain sysroot location for CC.
 UAPI_CFLAGS += $(USERCFLAGS)

Re: FAILED: patch "[PATCH] kbuild: hdrcheck: fix cross build with clang" failed to apply to 5.4-stable tree

[Nathan Chancellor]

On Tue, Jun 17, 2025 at 05:10:06PM +0200, gregkh@linuxfoundation.org wrote:
> From 02e9a22ceef0227175e391902d8760425fa072c6 Mon Sep 17 00:00:00 2001
> From: Arnd Bergmann <arnd@arndb.de>
> Date: Tue, 25 Feb 2025 11:00:31 +0100
> Subject: [PATCH] kbuild: hdrcheck: fix cross build with clang
> 
> The headercheck tries to call clang with a mix of compiler arguments
> that don't include the target architecture. When building e.g. x86
> headers on arm64, this produces a warning like
> 
>    clang: warning: unknown platform, assuming -mfloat-abi=soft
> 
> Add in the KBUILD_CPPFLAGS, which contain the target, in order to make it
> build properly.
> 
> See also 1b71c2fb04e7 ("kbuild: userprogs: fix bitsize and target
> detection on clang").
> 
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Fixes: feb843a469fb ("kbuild: add $(CLANG_FLAGS) to KBUILD_CPPFLAGS")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> 
> diff --git a/usr/include/Makefile b/usr/include/Makefile
> index 6c6de1b1622b..e3d6b03527fe 100644
> --- a/usr/include/Makefile
> +++ b/usr/include/Makefile
> @@ -10,7 +10,7 @@ UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration
>  
>  # In theory, we do not care -m32 or -m64 for header compile tests.
>  # It is here just because CONFIG_CC_CAN_LINK is tested with -m32 or -m64.
> -UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS))
> +UAPI_CFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
>  
>  # USERCFLAGS might contain sysroot location for CC.
>  UAPI_CFLAGS += $(USERCFLAGS)
> 

Commit 9fbed27a7a11 ("kbuild: add --target to correctly cross-compile
UAPI headers with Clang") in 5.18 introduced '--target=' here; prior to
that change, feb843a469fb would have no effect, so this change is
unnecessary for 5.15, 5.10, and 5.4 (the current 5.10 and 5.15 backports
are not harmful but they do not do anything as far as I can tell).

Cheers,
Nathan