diff mbox series

kbuild: move cc-option and cc-disable-warning after incl. arch Makefile

Message ID 1511784913-3396-1-git-send-email-yamada.masahiro@socionext.com
State Accepted
Commit cfe17c9bbe6a673fdafdab179c32b355ed447f66
Headers show
Series kbuild: move cc-option and cc-disable-warning after incl. arch Makefile | expand

Commit Message

Masahiro Yamada Nov. 27, 2017, 12:15 p.m. UTC 
Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before
incl. arch Makefile") broke cross-compilation using a cross-compiler
that supports less compiler options than the host compiler.

For example,

  cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

This problem happens on architectures that setup CROSS_COMPILE in their
arch/*/Makefile.

Move the cc-option and cc-disable-warning back to the original position,
but keep the Clang target options.

Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

---

 Makefile | 43 +++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

-- 
2.7.4

Comments

Geert Uytterhoeven Nov. 27, 2017, 12:25 p.m. UTC | #1 
Hi Yamada-san,

On Mon, Nov 27, 2017 at 1:15 PM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

> incl. arch Makefile") broke cross-compilation using a cross-compiler

> that supports less compiler options than the host compiler.

>

> For example,

>

>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

>

> This problem happens on architectures that setup CROSS_COMPILE in their

> arch/*/Makefile.

>

> Move the cc-option and cc-disable-warning back to the original position,

> but keep the Clang target options.

>

> Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")

> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>


Thanks for the quick response!

Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>


Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Masahiro Yamada Dec. 10, 2017, 5:28 a.m. UTC | #2 
2017-11-27 21:25 GMT+09:00 Geert Uytterhoeven <geert@linux-m68k.org>:
> Hi Yamada-san,

>

> On Mon, Nov 27, 2017 at 1:15 PM, Masahiro Yamada

> <yamada.masahiro@socionext.com> wrote:

>> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

>> incl. arch Makefile") broke cross-compilation using a cross-compiler

>> that supports less compiler options than the host compiler.

>>

>> For example,

>>

>>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

>>

>> This problem happens on architectures that setup CROSS_COMPILE in their

>> arch/*/Makefile.

>>

>> Move the cc-option and cc-disable-warning back to the original position,

>> but keep the Clang target options.

>>

>> Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")

>> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>

>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>

> Thanks for the quick response!

>

> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

>

> Gr{oetje,eeting}s,

>

>                         Geert



Applied to linux-kbuild/fixes.

-- 
Best Regards
Masahiro Yamada
Geert Uytterhoeven Jan. 10, 2018, 4:21 p.m. UTC | #3 
Hi Yamada-san,

On Sun, Dec 10, 2017 at 6:28 AM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> 2017-11-27 21:25 GMT+09:00 Geert Uytterhoeven <geert@linux-m68k.org>:

>> On Mon, Nov 27, 2017 at 1:15 PM, Masahiro Yamada

>> <yamada.masahiro@socionext.com> wrote:

>>> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

>>> incl. arch Makefile") broke cross-compilation using a cross-compiler

>>> that supports less compiler options than the host compiler.

>>>

>>> For example,

>>>

>>>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

>>>

>>> This problem happens on architectures that setup CROSS_COMPILE in their

>>> arch/*/Makefile.

>>>

>>> Move the cc-option and cc-disable-warning back to the original position,

>>> but keep the Clang target options.

>>>

>>> Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")

>>> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>

>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>>

>> Thanks for the quick response!

>>

>> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

>

> Applied to linux-kbuild/fixes.


Any chance this will be fixed in v4.15?
It fixes a regression introduced in v4.15-rc1.

Thanks again!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Masahiro Yamada Jan. 10, 2018, 4:39 p.m. UTC | #4 
2018-01-11 1:21 GMT+09:00 Geert Uytterhoeven <geert@linux-m68k.org>:
> Hi Yamada-san,

>

> On Sun, Dec 10, 2017 at 6:28 AM, Masahiro Yamada

> <yamada.masahiro@socionext.com> wrote:

>> 2017-11-27 21:25 GMT+09:00 Geert Uytterhoeven <geert@linux-m68k.org>:

>>> On Mon, Nov 27, 2017 at 1:15 PM, Masahiro Yamada

>>> <yamada.masahiro@socionext.com> wrote:

>>>> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

>>>> incl. arch Makefile") broke cross-compilation using a cross-compiler

>>>> that supports less compiler options than the host compiler.

>>>>

>>>> For example,

>>>>

>>>>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

>>>>

>>>> This problem happens on architectures that setup CROSS_COMPILE in their

>>>> arch/*/Makefile.

>>>>

>>>> Move the cc-option and cc-disable-warning back to the original position,

>>>> but keep the Clang target options.

>>>>

>>>> Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")

>>>> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>

>>>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

>>>

>>> Thanks for the quick response!

>>>

>>> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

>>

>> Applied to linux-kbuild/fixes.

>

> Any chance this will be fixed in v4.15?

> It fixes a regression introduced in v4.15-rc1.

>


Yes, of course.

I have queued up just two patches to the fixes branch.
I am expecting a little more fixes for make-cache issues,
but otherwise, I will send a pull request in a few days.


-- 
Best Regards
Masahiro Yamada
Stefan Agner March 19, 2018, 12:41 a.m. UTC | #5 
Hi Masahiro,

On 27.11.2017 13:15, Masahiro Yamada wrote:
> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

> incl. arch Makefile") broke cross-compilation using a cross-compiler

> that supports less compiler options than the host compiler.

> 

> For example,

> 

>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

> 

> This problem happens on architectures that setup CROSS_COMPILE in their

> arch/*/Makefile.

> 

> Move the cc-option and cc-disable-warning back to the original position,

> but keep the Clang target options.


This seems to break arm (32-bit) clang support for me. It seems to break
correct compiler flag detection in some way.

Just moving no-integrated-as back to before including the arch Makefile
seems to fix the issue:

--- a/Makefile
+++ b/Makefile
@@ -487,6 +487,7 @@ CLANG_GCC_TC        :=
--gcc-toolchain=$(GCC_TOOLCHAIN)
 endif
 KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
 KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
+KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
 endif
 
 RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern
-mindirect-branch-register
@@ -744,7 +745,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning,
tautological-compare)
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
 KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
-KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
 KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
 else

Does that sound like a reasonable fix?

Note that arm support is not completely upstream yet, but only few
patches are necessary currently:
http://git.agner.ch/gitweb/?p=linux.git;a=shortlog;h=refs/heads/v4.16-rc5-clang-arm-no-revert

--
Stefan


> 

> Fixes: ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before incl. arch Makefile")

> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>

> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>

> ---

> 

>  Makefile | 43 +++++++++++++++++++++++--------------------

>  1 file changed, 23 insertions(+), 20 deletions(-)

> 

> diff --git a/Makefile b/Makefile

> index aa67428..ac2d4e1 100644

> --- a/Makefile

> +++ b/Makefile

> @@ -484,26 +484,6 @@ CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)

>  endif

>  KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)

>  KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)

> -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)

> -KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)

> -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)

> -KBUILD_CFLAGS += $(call cc-disable-warning, gnu)

> -KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)

> -# Quiet clang warning: comparison of unsigned expression < 0 is always false

> -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)

> -# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the

> -# source of a reference will be _MergedGlobals and not on of the

> whitelisted names.

> -# See modpost pattern 2

> -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)

> -KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)

> -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

> -KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

> -else

> -

> -# These warnings generated too much noise in a regular build.

> -# Use make W=1 to enable them (see scripts/Makefile.extrawarn)

> -KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)

> -KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)

>  endif

>  

>  ifeq ($(config-targets),1)

> @@ -715,6 +695,29 @@ ifdef CONFIG_CC_STACKPROTECTOR

>  endif

>  KBUILD_CFLAGS += $(stackp-flag)

>  

> +ifeq ($(cc-name),clang)

> +KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)

> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)

> +KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)

> +KBUILD_CFLAGS += $(call cc-disable-warning, gnu)

> +KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)

> +# Quiet clang warning: comparison of unsigned expression < 0 is always false

> +KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)

> +# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the

> +# source of a reference will be _MergedGlobals and not on of the

> whitelisted names.

> +# See modpost pattern 2

> +KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)

> +KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)

> +KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

> +KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

> +else

> +

> +# These warnings generated too much noise in a regular build.

> +# Use make W=1 to enable them (see scripts/Makefile.extrawarn)

> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)

> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)

> +endif

> +

>  ifdef CONFIG_FRAME_POINTER

>  KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls

>  else
Masahiro Yamada March 19, 2018, 2:37 a.m. UTC | #6 
2018-03-19 9:41 GMT+09:00 Stefan Agner <stefan@agner.ch>:
> Hi Masahiro,

>

> On 27.11.2017 13:15, Masahiro Yamada wrote:

>> Geert reported commit ae6b289a3789 ("kbuild: Set KBUILD_CFLAGS before

>> incl. arch Makefile") broke cross-compilation using a cross-compiler

>> that supports less compiler options than the host compiler.

>>

>> For example,

>>

>>   cc1: error: unrecognized command line option "-Wno-unused-but-set-variable"

>>

>> This problem happens on architectures that setup CROSS_COMPILE in their

>> arch/*/Makefile.

>>

>> Move the cc-option and cc-disable-warning back to the original position,

>> but keep the Clang target options.

>

> This seems to break arm (32-bit) clang support for me. It seems to break

> correct compiler flag detection in some way.

>

> Just moving no-integrated-as back to before including the arch Makefile

> seems to fix the issue:


Sorry, looks like I broke it.



> --- a/Makefile

> +++ b/Makefile

> @@ -487,6 +487,7 @@ CLANG_GCC_TC        :=

> --gcc-toolchain=$(GCC_TOOLCHAIN)

>  endif

>  KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)

>  KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)

> +KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

>  endif

>

>  RETPOLINE_CFLAGS_GCC := -mindirect-branch=thunk-extern

> -mindirect-branch-register

> @@ -744,7 +745,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning,

> tautological-compare)

>  # See modpost pattern 2

>  KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)

>  KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)

> -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)

>  KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)

>  else

>

> Does that sound like a reasonable fix?



Yes, I think so.


For consistency, please move
KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
as well.




-- 
Best Regards
Masahiro Yamada
diff mbox series

Patch

diff --git a/Makefile b/Makefile
index aa67428..ac2d4e1 100644
--- a/Makefile
+++ b/Makefile
@@ -484,26 +484,6 @@  CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)
 endif
 KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
 KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC)
-KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
-KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
-KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
-KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
-# Quiet clang warning: comparison of unsigned expression < 0 is always false
-KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
-# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
-# source of a reference will be _MergedGlobals and not on of the whitelisted names.
-# See modpost pattern 2
-KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
-KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
-KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
-KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
-else
-
-# These warnings generated too much noise in a regular build.
-# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
-KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 endif
 
 ifeq ($(config-targets),1)
@@ -715,6 +695,29 @@  ifdef CONFIG_CC_STACKPROTECTOR
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
+ifeq ($(cc-name),clang)
+KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
+KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
+KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
+# Quiet clang warning: comparison of unsigned expression < 0 is always false
+KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
+# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
+# source of a reference will be _MergedGlobals and not on of the whitelisted names.
+# See modpost pattern 2
+KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
+KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
+KBUILD_CFLAGS += $(call cc-option, -no-integrated-as)
+KBUILD_AFLAGS += $(call cc-option, -no-integrated-as)
+else
+
+# These warnings generated too much noise in a regular build.
+# Use make W=1 to enable them (see scripts/Makefile.extrawarn)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
+endif
+
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 else