Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On 2015-08-27 10:37, Michal Marek wrote:
> On 2015-08-27 03:49, Behan Webster wrote:
>> Is there any reason you renamed COMPILER? Because it breaks all the 
>> other patches we have queued up which use it for cross compiling.
>>
>> And aren't we supposed to use all caps for variable names?
> 
> It more like a function now and is consistent with the other cc-*
> definitions in scripts/Kbuild.include.
> 
> 
>> This doesn't only break powerpc, it breaks arm, aarch64 and clang work 
>> that's being done on MIPS malta.
> 
> So do a s/COMPILER/cc-name/ ? You can merge my patch into your tree to
> avoid a dependency on the kbuild tree.

Since I haven't seen any further uses of the $(CLANG) variable in
linux-next, I applied the patch to kbuild.git now.

Michal
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On 2015-08-27 10:37, Michal Marek wrote:
> On 2015-08-27 03:49, Behan Webster wrote:
>> Is there any reason you renamed COMPILER? Because it breaks all the 
>> other patches we have queued up which use it for cross compiling.
>>
>> And aren't we supposed to use all caps for variable names?
> 
> It more like a function now and is consistent with the other cc-*
> definitions in scripts/Kbuild.include.
> 
> 
>> This doesn't only break powerpc, it breaks arm, aarch64 and clang work 
>> that's being done on MIPS malta.
> 
> So do a s/COMPILER/cc-name/ ? You can merge my patch into your tree to
> avoid a dependency on the kbuild tree.

Since I haven't seen any further uses of the $(CLANG) variable in
linux-next, I applied the patch to kbuild.git now.

Michal
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On 2015-08-27 03:49, Behan Webster wrote:
> 
> On 08/19/15 08:41, Michal Marek wrote:
>>  From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
>> From: Michal Marek 
>> Date: Wed, 19 Aug 2015 17:36:41 +0200
>> Subject: [PATCH] kbuild: Fix clang detection
>>
>> We cannot detect clang before including the arch Makefile, because that
>> can set the default cross compiler. We also cannot detect clang after
>> including the arch Makefile, because powerpc wants to know about clang.
>> Solve this by using an deferred variable. This costs us a few shell
>> invocations, but this is only a constant number.
>>
>> Reported-by: Behan Webster 
>> Reported-by: Anton Blanchard 
>> Signed-off-by: Michal Marek 
>> ---
>>   Makefile   | 9 +
>>   arch/powerpc/Makefile  | 8 
>>   scripts/Kbuild.include | 4 
>>   scripts/Makefile.extrawarn | 2 +-
>>   4 files changed, 10 insertions(+), 13 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 13270c0..5ccbb58 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -661,14 +661,7 @@ endif
>>   endif
>>   KBUILD_CFLAGS += $(stackp-flag)
>>   
>> -ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
>> -COMPILER := clang
>> -else
>> -COMPILER := gcc
>> -endif
>> -export COMPILER
>> -
>> -ifeq ($(COMPILER),clang)
>> +ifeq ($(cc-name),clang)
>>   KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
>>   KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
>>   KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
>> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
>> index 05f464e..dfe88896 100644
>> --- a/arch/powerpc/Makefile
>> +++ b/arch/powerpc/Makefile
>> @@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
>>   
>>   ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
>>   override CC+= -mlittle-endian
>> -ifneq ($(COMPILER),clang)
>> +ifneq ($(cc-name),clang)
>>   override CC+= -mno-strict-align
>>   endif
>>   override AS+= -mlittle-endian
>> @@ -333,7 +333,7 @@ TOUT := .tmp_gas_check
>>   # - Require gcc 4.0 or above on 64-bit
>>   # - gcc-4.2.0 has issues compiling modules on 64-bit
>>   checkbin:
>> -@if test "${COMPILER}" != "clang" \
>> +@if test "$(cc-name)" != "clang" \
>>  && test "$(cc-version)" = "0304" ; then \
>>  if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) 
>> >/dev/null 2>&1 ; then \
>>  echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
>> build '; \
>> @@ -342,14 +342,14 @@ checkbin:
>>  false; \
>>  fi ; \
>>  fi
>> -@if test "${COMPILER}" != "clang" \
>> +@if test "$(cc-name)" != "clang" \
>>  && test "$(cc-version)" -lt "0400" \
>>  && test "x${CONFIG_PPC64}" = "xy" ; then \
>>   echo -n "Sorry, GCC v4.0 or above is required to build " ; 
>> \
>>   echo "the 64-bit powerpc kernel." ; \
>>   false ; \
>>   fi
>> -@if test "${COMPILER}" != "clang" \
>> +@if test "$(cc-name)" != "clang" \
>>  && test "$(cc-fullversion)" = "040200" \
>>  && test "x${CONFIG_MODULES}${CONFIG_PPC64}" = "xyy" ; then \
>>  echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
>> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
>> index d3437b8..3523df6 100644
>> --- a/scripts/Kbuild.include
>> +++ b/scripts/Kbuild.include
>> @@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
>>   cc-disable-warning = $(call try-run,\
>>  $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c 
>> /dev/null -o "$$TMP",-Wno-$(strip $(1)))
>>   
>> +# cc-name
>> +# Expands to either gcc or clang
>> +cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || 
>> echo gcc)
>> +
>>   # cc-version
>>   cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh 
>> $(CC))
>>   
>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
>> index f734033..4efedcb 100644
>> --- a/scripts/Makefile.extrawarn
>> +++ b/scripts/Makefile.extrawarn
>> @@ -56,7 +56,7 @@ endif
>>   KBUILD_CFLAGS += $(warning)
>>   else
>>   
>> -ifeq ($(COMPILER),clang)
>> +ifeq ($(cc-name),clang)
>>   KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
>>   KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
>>   KBUILD_CFLAGS += $(call cc-disable-warning, format)
> 
> Is there any reason you renamed COMPILER? Because it breaks all the 
> other patches we have queued up which use it for cross compiling.
> 
> And aren't we supposed to use all caps for variable names?

It more like a function now and is consistent with the other cc-*
definitions in scripts/Kbuild.include.


> This doesn't only break powerpc, it breaks arm, aarch64 and clang work 
> that's being done on MIPS malta.

So do a s/COMPILER/cc-name/ ? You can merge my patch into your tree to
avoid a dependency on the kbuild tree.


> The big reason I 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On 2015-08-27 03:49, Behan Webster wrote:
 
 On 08/19/15 08:41, Michal Marek wrote:
  From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
 From: Michal Marek mma...@suse.com
 Date: Wed, 19 Aug 2015 17:36:41 +0200
 Subject: [PATCH] kbuild: Fix clang detection

 We cannot detect clang before including the arch Makefile, because that
 can set the default cross compiler. We also cannot detect clang after
 including the arch Makefile, because powerpc wants to know about clang.
 Solve this by using an deferred variable. This costs us a few shell
 invocations, but this is only a constant number.

 Reported-by: Behan Webster beh...@converseincode.com
 Reported-by: Anton Blanchard an...@samba.org
 Signed-off-by: Michal Marek mma...@suse.com
 ---
   Makefile   | 9 +
   arch/powerpc/Makefile  | 8 
   scripts/Kbuild.include | 4 
   scripts/Makefile.extrawarn | 2 +-
   4 files changed, 10 insertions(+), 13 deletions(-)

 diff --git a/Makefile b/Makefile
 index 13270c0..5ccbb58 100644
 --- a/Makefile
 +++ b/Makefile
 @@ -661,14 +661,7 @@ endif
   endif
   KBUILD_CFLAGS += $(stackp-flag)
   
 -ifeq ($(shell $(CC) -v 21 | grep -c clang version), 1)
 -COMPILER := clang
 -else
 -COMPILER := gcc
 -endif
 -export COMPILER
 -
 -ifeq ($(COMPILER),clang)
 +ifeq ($(cc-name),clang)
   KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
   KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
   KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
 diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
 index 05f464e..dfe88896 100644
 --- a/arch/powerpc/Makefile
 +++ b/arch/powerpc/Makefile
 @@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
   
   ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
   override CC+= -mlittle-endian
 -ifneq ($(COMPILER),clang)
 +ifneq ($(cc-name),clang)
   override CC+= -mno-strict-align
   endif
   override AS+= -mlittle-endian
 @@ -333,7 +333,7 @@ TOUT := .tmp_gas_check
   # - Require gcc 4.0 or above on 64-bit
   # - gcc-4.2.0 has issues compiling modules on 64-bit
   checkbin:
 -@if test ${COMPILER} != clang \
 +@if test $(cc-name) != clang \
   test $(cc-version) = 0304 ; then \
  if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) 
 /dev/null 21 ; then \
  echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
 build '; \
 @@ -342,14 +342,14 @@ checkbin:
  false; \
  fi ; \
  fi
 -@if test ${COMPILER} != clang \
 +@if test $(cc-name) != clang \
   test $(cc-version) -lt 0400 \
   test x${CONFIG_PPC64} = xy ; then \
   echo -n Sorry, GCC v4.0 or above is required to build  ; 
 \
   echo the 64-bit powerpc kernel. ; \
   false ; \
   fi
 -@if test ${COMPILER} != clang \
 +@if test $(cc-name) != clang \
   test $(cc-fullversion) = 040200 \
   test x${CONFIG_MODULES}${CONFIG_PPC64} = xyy ; then \
  echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
 diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
 index d3437b8..3523df6 100644
 --- a/scripts/Kbuild.include
 +++ b/scripts/Kbuild.include
 @@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
   cc-disable-warning = $(call try-run,\
  $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c 
 /dev/null -o $$TMP,-Wno-$(strip $(1)))
   
 +# cc-name
 +# Expands to either gcc or clang
 +cc-name = $(shell $(CC) -v 21 | grep -q clang version  echo clang || 
 echo gcc)
 +
   # cc-version
   cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh 
 $(CC))
   
 diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
 index f734033..4efedcb 100644
 --- a/scripts/Makefile.extrawarn
 +++ b/scripts/Makefile.extrawarn
 @@ -56,7 +56,7 @@ endif
   KBUILD_CFLAGS += $(warning)
   else
   
 -ifeq ($(COMPILER),clang)
 +ifeq ($(cc-name),clang)
   KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
   KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
   KBUILD_CFLAGS += $(call cc-disable-warning, format)
 
 Is there any reason you renamed COMPILER? Because it breaks all the 
 other patches we have queued up which use it for cross compiling.
 
 And aren't we supposed to use all caps for variable names?

It more like a function now and is consistent with the other cc-*
definitions in scripts/Kbuild.include.


 This doesn't only break powerpc, it breaks arm, aarch64 and clang work 
 that's being done on MIPS malta.

So do a s/COMPILER/cc-name/ ? You can merge my patch into your tree to
avoid a dependency on the kbuild tree.


 The big reason I wrote it the way I did was so other compilers could be 
 added as well (as if-then-else stanzas).
 
 I understand that the initial issue was that if /usr/bin/cc was clang 
 things broke for MIPS, but that's just a temporal problem as we 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Behan Webster]

On 08/19/15 08:41, Michal Marek wrote:

On Mon, Jul 13, 2015 at 08:59:33PM +1000, Anton Blanchard wrote:

Hi,


  > When the host's C compiler is clang, and when attempting to
  > cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
  > Makefile would incorrectly detect the use of clang, which
  > resulted in clang-specific flags being passed to
  > mipsel-linux-gcc.
  >
  > This can be verified under Debian by installing the "clang"
  > package, and then using it as the default compiler with:
  > sudo update-alternatives --config cc
  >
  > This patch moves the detection of clang after the $(CC)
  > variable is initialized to the name of the cross-compiler, so
  > that the check applies
  > to the cross-compiler and not the host's C compiler.
  >
  > v2: Move the detection of clang after the inclusion of the
  > arch/*/Makefile (as they might set $(CROSS_COMPILE))
  >
  > Signed-off-by: Paul Cercueil mailto:p...@crapouillou.net>>

 Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
 becomes available, though.

Drat. I wish I saw this earlier.

This breaks patches which check for the value of COMPILER in
arch/*/Makefile. This detection must be performed before the
inclusion of the arch Makefile.

Can I move this to after the initialization of CC but before the
include?

I'm not sure that being able to define the default compiler per arch
is necessary. But I know I need to be able to add arch specific flags
for clang.

I can confirm the patch breaks ppc64le clang builds.

Can you try the (untested) patch below?


 From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
From: Michal Marek 
Date: Wed, 19 Aug 2015 17:36:41 +0200
Subject: [PATCH] kbuild: Fix clang detection

We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.

Reported-by: Behan Webster 
Reported-by: Anton Blanchard 
Signed-off-by: Michal Marek 
---
  Makefile   | 9 +
  arch/powerpc/Makefile  | 8 
  scripts/Kbuild.include | 4 
  scripts/Makefile.extrawarn | 2 +-
  4 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index 13270c0..5ccbb58 100644
--- a/Makefile
+++ b/Makefile
@@ -661,14 +661,7 @@ endif
  endif
  KBUILD_CFLAGS += $(stackp-flag)
  
-ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)

-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-
-ifeq ($(COMPILER),clang)
+ifeq ($(cc-name),clang)
  KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
  KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
  KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 05f464e..dfe88896 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
  
  ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)

  override CC   += -mlittle-endian
-ifneq ($(COMPILER),clang)
+ifneq ($(cc-name),clang)
  override CC   += -mno-strict-align
  endif
  override AS   += -mlittle-endian
@@ -333,7 +333,7 @@ TOUT:= .tmp_gas_check
  # - Require gcc 4.0 or above on 64-bit
  # - gcc-4.2.0 has issues compiling modules on 64-bit
  checkbin:
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" = "0304" ; then \
if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) >/dev/null 
2>&1 ; then \
echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
build '; \
@@ -342,14 +342,14 @@ checkbin:
false; \
fi ; \
fi
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" -lt "0400" \
&& test "x${CONFIG_PPC64}" = "xy" ; then \
  echo -n "Sorry, GCC v4.0 or above is required to build " ; \
  echo "the 64-bit powerpc kernel." ; \
  false ; \
  fi
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-fullversion)" = "040200" \
&& test "x${CONFIG_MODULES}${CONFIG_PPC64}" = "xyy" ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d3437b8..3523df6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
  cc-disable-warning = $(call try-run,\
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o 
"$$TMP",-Wno-$(strip 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Behan Webster]

On 08/19/15 08:41, Michal Marek wrote:

On Mon, Jul 13, 2015 at 08:59:33PM +1000, Anton Blanchard wrote:

Hi,


   When the host's C compiler is clang, and when attempting to
   cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
   Makefile would incorrectly detect the use of clang, which
   resulted in clang-specific flags being passed to
   mipsel-linux-gcc.
  
   This can be verified under Debian by installing the clang
   package, and then using it as the default compiler with:
   sudo update-alternatives --config cc
  
   This patch moves the detection of clang after the $(CC)
   variable is initialized to the name of the cross-compiler, so
   that the check applies
   to the cross-compiler and not the host's C compiler.
  
   v2: Move the detection of clang after the inclusion of the
   arch/*/Makefile (as they might set $(CROSS_COMPILE))
  
   Signed-off-by: Paul Cercueil p...@crapouillou.net
 mailto:p...@crapouillou.net

 Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
 becomes available, though.

Drat. I wish I saw this earlier.

This breaks patches which check for the value of COMPILER in
arch/*/Makefile. This detection must be performed before the
inclusion of the arch Makefile.

Can I move this to after the initialization of CC but before the
include?

I'm not sure that being able to define the default compiler per arch
is necessary. But I know I need to be able to add arch specific flags
for clang.

I can confirm the patch breaks ppc64le clang builds.

Can you try the (untested) patch below?


 From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
From: Michal Marek mma...@suse.com
Date: Wed, 19 Aug 2015 17:36:41 +0200
Subject: [PATCH] kbuild: Fix clang detection

We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.

Reported-by: Behan Webster beh...@converseincode.com
Reported-by: Anton Blanchard an...@samba.org
Signed-off-by: Michal Marek mma...@suse.com
---
  Makefile   | 9 +
  arch/powerpc/Makefile  | 8 
  scripts/Kbuild.include | 4 
  scripts/Makefile.extrawarn | 2 +-
  4 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index 13270c0..5ccbb58 100644
--- a/Makefile
+++ b/Makefile
@@ -661,14 +661,7 @@ endif
  endif
  KBUILD_CFLAGS += $(stackp-flag)
  
-ifeq ($(shell $(CC) -v 21 | grep -c clang version), 1)

-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-
-ifeq ($(COMPILER),clang)
+ifeq ($(cc-name),clang)
  KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
  KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
  KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 05f464e..dfe88896 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
  
  ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)

  override CC   += -mlittle-endian
-ifneq ($(COMPILER),clang)
+ifneq ($(cc-name),clang)
  override CC   += -mno-strict-align
  endif
  override AS   += -mlittle-endian
@@ -333,7 +333,7 @@ TOUT:= .tmp_gas_check
  # - Require gcc 4.0 or above on 64-bit
  # - gcc-4.2.0 has issues compiling modules on 64-bit
  checkbin:
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-version) = 0304 ; then \
if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) /dev/null 
21 ; then \
echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
build '; \
@@ -342,14 +342,14 @@ checkbin:
false; \
fi ; \
fi
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-version) -lt 0400 \
 test x${CONFIG_PPC64} = xy ; then \
  echo -n Sorry, GCC v4.0 or above is required to build  ; \
  echo the 64-bit powerpc kernel. ; \
  false ; \
  fi
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-fullversion) = 040200 \
 test x${CONFIG_MODULES}${CONFIG_PPC64} = xyy ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d3437b8..3523df6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
  cc-disable-warning = $(call try-run,\
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On Mon, Jul 13, 2015 at 08:59:33PM +1000, Anton Blanchard wrote:
> Hi,
> 
> >  > When the host's C compiler is clang, and when attempting to
> >  > cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
> >  > Makefile would incorrectly detect the use of clang, which
> >  > resulted in clang-specific flags being passed to
> >  > mipsel-linux-gcc.
> >  >
> >  > This can be verified under Debian by installing the "clang"
> >  > package, and then using it as the default compiler with:
> >  > sudo update-alternatives --config cc
> >  >
> >  > This patch moves the detection of clang after the $(CC)
> >  > variable is initialized to the name of the cross-compiler, so
> >  > that the check applies
> >  > to the cross-compiler and not the host's C compiler.
> >  >
> >  > v2: Move the detection of clang after the inclusion of the
> >  > arch/*/Makefile (as they might set $(CROSS_COMPILE))
> >  >
> >  > Signed-off-by: Paul Cercueil  > >
> > 
> > Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
> > becomes available, though.
> > 
> > Drat. I wish I saw this earlier.
> > 
> > This breaks patches which check for the value of COMPILER in 
> > arch/*/Makefile. This detection must be performed before the
> > inclusion of the arch Makefile.
> > 
> > Can I move this to after the initialization of CC but before the
> > include?
> > 
> > I'm not sure that being able to define the default compiler per arch
> > is necessary. But I know I need to be able to add arch specific flags
> > for clang.
> 
> I can confirm the patch breaks ppc64le clang builds.

Can you try the (untested) patch below?


>From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
From: Michal Marek 
Date: Wed, 19 Aug 2015 17:36:41 +0200
Subject: [PATCH] kbuild: Fix clang detection

We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.

Reported-by: Behan Webster 
Reported-by: Anton Blanchard 
Signed-off-by: Michal Marek 
---
 Makefile   | 9 +
 arch/powerpc/Makefile  | 8 
 scripts/Kbuild.include | 4 
 scripts/Makefile.extrawarn | 2 +-
 4 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index 13270c0..5ccbb58 100644
--- a/Makefile
+++ b/Makefile
@@ -661,14 +661,7 @@ endif
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
-ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-
-ifeq ($(COMPILER),clang)
+ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 05f464e..dfe88896 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
 
 ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
 override CC+= -mlittle-endian
-ifneq ($(COMPILER),clang)
+ifneq ($(cc-name),clang)
 override CC+= -mno-strict-align
 endif
 override AS+= -mlittle-endian
@@ -333,7 +333,7 @@ TOUT:= .tmp_gas_check
 # - Require gcc 4.0 or above on 64-bit
 # - gcc-4.2.0 has issues compiling modules on 64-bit
 checkbin:
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" = "0304" ; then \
if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) 
>/dev/null 2>&1 ; then \
echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
build '; \
@@ -342,14 +342,14 @@ checkbin:
false; \
fi ; \
fi
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-version)" -lt "0400" \
&& test "x${CONFIG_PPC64}" = "xy" ; then \
 echo -n "Sorry, GCC v4.0 or above is required to build " ; \
 echo "the 64-bit powerpc kernel." ; \
 false ; \
 fi
-   @if test "${COMPILER}" != "clang" \
+   @if test "$(cc-name)" != "clang" \
&& test "$(cc-fullversion)" = "040200" \
&& test "x${CONFIG_MODULES}${CONFIG_PPC64}" = "xyy" ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d3437b8..3523df6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
 cc-disable-warning = $(call try-run,\
$(CC) $(KBUILD_CPPFLAGS) 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On Mon, Jul 13, 2015 at 08:59:33PM +1000, Anton Blanchard wrote:
 Hi,
 
When the host's C compiler is clang, and when attempting to
cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
Makefile would incorrectly detect the use of clang, which
resulted in clang-specific flags being passed to
mipsel-linux-gcc.
   
This can be verified under Debian by installing the clang
package, and then using it as the default compiler with:
sudo update-alternatives --config cc
   
This patch moves the detection of clang after the $(CC)
variable is initialized to the name of the cross-compiler, so
that the check applies
to the cross-compiler and not the host's C compiler.
   
v2: Move the detection of clang after the inclusion of the
arch/*/Makefile (as they might set $(CROSS_COMPILE))
   
Signed-off-by: Paul Cercueil p...@crapouillou.net
  mailto:p...@crapouillou.net
  
  Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
  becomes available, though.
  
  Drat. I wish I saw this earlier.
  
  This breaks patches which check for the value of COMPILER in 
  arch/*/Makefile. This detection must be performed before the
  inclusion of the arch Makefile.
  
  Can I move this to after the initialization of CC but before the
  include?
  
  I'm not sure that being able to define the default compiler per arch
  is necessary. But I know I need to be able to add arch specific flags
  for clang.
 
 I can confirm the patch breaks ppc64le clang builds.

Can you try the (untested) patch below?


From 49bb3e66a9a7fc3685fb070bdfd31f2c3d78cc87 Mon Sep 17 00:00:00 2001
From: Michal Marek mma...@suse.com
Date: Wed, 19 Aug 2015 17:36:41 +0200
Subject: [PATCH] kbuild: Fix clang detection

We cannot detect clang before including the arch Makefile, because that
can set the default cross compiler. We also cannot detect clang after
including the arch Makefile, because powerpc wants to know about clang.
Solve this by using an deferred variable. This costs us a few shell
invocations, but this is only a constant number.

Reported-by: Behan Webster beh...@converseincode.com
Reported-by: Anton Blanchard an...@samba.org
Signed-off-by: Michal Marek mma...@suse.com
---
 Makefile   | 9 +
 arch/powerpc/Makefile  | 8 
 scripts/Kbuild.include | 4 
 scripts/Makefile.extrawarn | 2 +-
 4 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/Makefile b/Makefile
index 13270c0..5ccbb58 100644
--- a/Makefile
+++ b/Makefile
@@ -661,14 +661,7 @@ endif
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
-ifeq ($(shell $(CC) -v 21 | grep -c clang version), 1)
-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-
-ifeq ($(COMPILER),clang)
+ifeq ($(cc-name),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 05f464e..dfe88896 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,7 @@ UTS_MACHINE := $(OLDARCH)
 
 ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
 override CC+= -mlittle-endian
-ifneq ($(COMPILER),clang)
+ifneq ($(cc-name),clang)
 override CC+= -mno-strict-align
 endif
 override AS+= -mlittle-endian
@@ -333,7 +333,7 @@ TOUT:= .tmp_gas_check
 # - Require gcc 4.0 or above on 64-bit
 # - gcc-4.2.0 has issues compiling modules on 64-bit
 checkbin:
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-version) = 0304 ; then \
if ! /bin/echo mftb 5 | $(AS) -v -mppc -many -o $(TOUT) 
/dev/null 21 ; then \
echo -n '*** ${VERSION}.${PATCHLEVEL} kernels no longer 
build '; \
@@ -342,14 +342,14 @@ checkbin:
false; \
fi ; \
fi
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-version) -lt 0400 \
 test x${CONFIG_PPC64} = xy ; then \
 echo -n Sorry, GCC v4.0 or above is required to build  ; \
 echo the 64-bit powerpc kernel. ; \
 false ; \
 fi
-   @if test ${COMPILER} != clang \
+   @if test $(cc-name) != clang \
 test $(cc-fullversion) = 040200 \
 test x${CONFIG_MODULES}${CONFIG_PPC64} = xyy ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index d3437b8..3523df6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -128,6 +128,10 @@ cc-option-align = $(subst -functions=0,,\
 cc-disable-warning = $(call try-run,\
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c 
/dev/null -o $$TMP,-Wno-$(strip $(1)))
 

Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Anton Blanchard]

Hi,

>  > When the host's C compiler is clang, and when attempting to
>  > cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
>  > Makefile would incorrectly detect the use of clang, which
>  > resulted in clang-specific flags being passed to
>  > mipsel-linux-gcc.
>  >
>  > This can be verified under Debian by installing the "clang"
>  > package, and then using it as the default compiler with:
>  > sudo update-alternatives --config cc
>  >
>  > This patch moves the detection of clang after the $(CC)
>  > variable is initialized to the name of the cross-compiler, so
>  > that the check applies
>  > to the cross-compiler and not the host's C compiler.
>  >
>  > v2: Move the detection of clang after the inclusion of the
>  > arch/*/Makefile (as they might set $(CROSS_COMPILE))
>  >
>  > Signed-off-by: Paul Cercueil  >
> 
> Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
> becomes available, though.
> 
> Drat. I wish I saw this earlier.
> 
> This breaks patches which check for the value of COMPILER in 
> arch/*/Makefile. This detection must be performed before the
> inclusion of the arch Makefile.
> 
> Can I move this to after the initialization of CC but before the
> include?
> 
> I'm not sure that being able to define the default compiler per arch
> is necessary. But I know I need to be able to add arch specific flags
> for clang.

I can confirm the patch breaks ppc64le clang builds.

Anton
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Anton Blanchard]

Hi,

   When the host's C compiler is clang, and when attempting to
   cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the
   Makefile would incorrectly detect the use of clang, which
   resulted in clang-specific flags being passed to
   mipsel-linux-gcc.
  
   This can be verified under Debian by installing the clang
   package, and then using it as the default compiler with:
   sudo update-alternatives --config cc
  
   This patch moves the detection of clang after the $(CC)
   variable is initialized to the name of the cross-compiler, so
   that the check applies
   to the cross-compiler and not the host's C compiler.
  
   v2: Move the detection of clang after the inclusion of the
   arch/*/Makefile (as they might set $(CROSS_COMPILE))
  
   Signed-off-by: Paul Cercueil p...@crapouillou.net
 mailto:p...@crapouillou.net
 
 Applied to kbuild.git#kbuild. I will push it after v4.1-rc1
 becomes available, though.
 
 Drat. I wish I saw this earlier.
 
 This breaks patches which check for the value of COMPILER in 
 arch/*/Makefile. This detection must be performed before the
 inclusion of the arch Makefile.
 
 Can I move this to after the initialization of CC but before the
 include?
 
 I'm not sure that being able to define the default compiler per arch
 is necessary. But I know I need to be able to add arch specific flags
 for clang.

I can confirm the patch breaks ppc64le clang builds.

Anton
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Behan Webster]

Resent since gmail HTML-ified my previous email...

On Wed, Apr 22, 2015 at 7:33 AM, Michal Marek > wrote:


   On Fri, Apr 17, 2015 at 11:35:04PM +0200, Paul Cercueil wrote:
> When the host's C compiler is clang, and when attempting to
> cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
> would incorrectly detect the use of clang, which resulted in
> clang-specific flags being passed to mipsel-linux-gcc.
>
> This can be verified under Debian by installing the "clang" package,
> and then using it as the default compiler with:
> sudo update-alternatives --config cc
>
> This patch moves the detection of clang after the $(CC) variable is
> initialized to the name of the cross-compiler, so that the check
   applies
> to the cross-compiler and not the host's C compiler.
>
> v2: Move the detection of clang after the inclusion of the
> arch/*/Makefile (as they might set $(CROSS_COMPILE))
>
> Signed-off-by: Paul Cercueil mailto:p...@crapouillou.net>>

   Applied to kbuild.git#kbuild. I will push it after v4.1-rc1 becomes
   available, though.


Drat. I wish I saw this earlier.

This breaks patches which check for the value of COMPILER in 
arch/*/Makefile. This detection must be performed before the inclusion 
of the arch Makefile.


Can I move this to after the initialization of CC but before the include?

I'm not sure that being able to define the default compiler per arch is 
necessary. But I know I need to be able to add arch specific flags for 
clang.


Behan

--
Behan Webster
beh...@converseincode.com 
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Behan Webster]

Resent since gmail HTML-ified my previous email...

On Wed, Apr 22, 2015 at 7:33 AM, Michal Marek mma...@suse.cz 
mailto:mma...@suse.cz wrote:


   On Fri, Apr 17, 2015 at 11:35:04PM +0200, Paul Cercueil wrote:
 When the host's C compiler is clang, and when attempting to
 cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
 would incorrectly detect the use of clang, which resulted in
 clang-specific flags being passed to mipsel-linux-gcc.

 This can be verified under Debian by installing the clang package,
 and then using it as the default compiler with:
 sudo update-alternatives --config cc

 This patch moves the detection of clang after the $(CC) variable is
 initialized to the name of the cross-compiler, so that the check
   applies
 to the cross-compiler and not the host's C compiler.

 v2: Move the detection of clang after the inclusion of the
 arch/*/Makefile (as they might set $(CROSS_COMPILE))

 Signed-off-by: Paul Cercueil p...@crapouillou.net
   mailto:p...@crapouillou.net

   Applied to kbuild.git#kbuild. I will push it after v4.1-rc1 becomes
   available, though.


Drat. I wish I saw this earlier.

This breaks patches which check for the value of COMPILER in 
arch/*/Makefile. This detection must be performed before the inclusion 
of the arch Makefile.


Can I move this to after the initialization of CC but before the include?

I'm not sure that being able to define the default compiler per arch is 
necessary. But I know I need to be able to add arch specific flags for 
clang.


Behan

--
Behan Webster
beh...@converseincode.com mailto:beh...@converseincode.com
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On Fri, Apr 17, 2015 at 11:35:04PM +0200, Paul Cercueil wrote:
> When the host's C compiler is clang, and when attempting to
> cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
> would incorrectly detect the use of clang, which resulted in
> clang-specific flags being passed to mipsel-linux-gcc.
> 
> This can be verified under Debian by installing the "clang" package,
> and then using it as the default compiler with:
> sudo update-alternatives --config cc
> 
> This patch moves the detection of clang after the $(CC) variable is
> initialized to the name of the cross-compiler, so that the check applies
> to the cross-compiler and not the host's C compiler.
> 
> v2: Move the detection of clang after the inclusion of the
> arch/*/Makefile (as they might set $(CROSS_COMPILE))
> 
> Signed-off-by: Paul Cercueil 

Applied to kbuild.git#kbuild. I will push it after v4.1-rc1 becomes
available, though.

Michal
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Re: [PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Michal Marek]

On Fri, Apr 17, 2015 at 11:35:04PM +0200, Paul Cercueil wrote:
 When the host's C compiler is clang, and when attempting to
 cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
 would incorrectly detect the use of clang, which resulted in
 clang-specific flags being passed to mipsel-linux-gcc.
 
 This can be verified under Debian by installing the clang package,
 and then using it as the default compiler with:
 sudo update-alternatives --config cc
 
 This patch moves the detection of clang after the $(CC) variable is
 initialized to the name of the cross-compiler, so that the check applies
 to the cross-compiler and not the host's C compiler.
 
 v2: Move the detection of clang after the inclusion of the
 arch/*/Makefile (as they might set $(CROSS_COMPILE))
 
 Signed-off-by: Paul Cercueil p...@crapouillou.net

Applied to kbuild.git#kbuild. I will push it after v4.1-rc1 becomes
available, though.

Michal
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Please read the FAQ at  http://www.tux.org/lkml/

[PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Paul Cercueil]

When the host's C compiler is clang, and when attempting to
cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
would incorrectly detect the use of clang, which resulted in
clang-specific flags being passed to mipsel-linux-gcc.

This can be verified under Debian by installing the "clang" package,
and then using it as the default compiler with:
sudo update-alternatives --config cc

This patch moves the detection of clang after the $(CC) variable is
initialized to the name of the cross-compiler, so that the check applies
to the cross-compiler and not the host's C compiler.

v2: Move the detection of clang after the inclusion of the
arch/*/Makefile (as they might set $(CROSS_COMPILE))

Signed-off-by: Paul Cercueil 
---
 Makefile | 16 +++-
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index fbd43bf..e1e8c7e 100644
--- a/Makefile
+++ b/Makefile
@@ -335,15 +335,6 @@ endif
 export KBUILD_MODULES KBUILD_BUILTIN
 export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD
 
-ifneq ($(CC),)
-ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-endif
-
 # Look for make include files relative to root of kernel src
 MAKEFLAGS += --include-dir=$(srctree)
 
@@ -673,6 +664,13 @@ endif
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
+ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
+COMPILER := clang
+else
+COMPILER := gcc
+endif
+export COMPILER
+
 ifeq ($(COMPILER),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
-- 
2.1.4

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[PATCH v2] Makefile: Fix detection of clang when cross-compiling

[Paul Cercueil]

When the host's C compiler is clang, and when attempting to
cross-compile Linux e.g. to MIPS with mipsel-linux-gcc, the Makefile
would incorrectly detect the use of clang, which resulted in
clang-specific flags being passed to mipsel-linux-gcc.

This can be verified under Debian by installing the clang package,
and then using it as the default compiler with:
sudo update-alternatives --config cc

This patch moves the detection of clang after the $(CC) variable is
initialized to the name of the cross-compiler, so that the check applies
to the cross-compiler and not the host's C compiler.

v2: Move the detection of clang after the inclusion of the
arch/*/Makefile (as they might set $(CROSS_COMPILE))

Signed-off-by: Paul Cercueil p...@crapouillou.net
---
 Makefile | 16 +++-
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index fbd43bf..e1e8c7e 100644
--- a/Makefile
+++ b/Makefile
@@ -335,15 +335,6 @@ endif
 export KBUILD_MODULES KBUILD_BUILTIN
 export KBUILD_CHECKSRC KBUILD_SRC KBUILD_EXTMOD
 
-ifneq ($(CC),)
-ifeq ($(shell $(CC) -v 21 | grep -c clang version), 1)
-COMPILER := clang
-else
-COMPILER := gcc
-endif
-export COMPILER
-endif
-
 # Look for make include files relative to root of kernel src
 MAKEFLAGS += --include-dir=$(srctree)
 
@@ -673,6 +664,13 @@ endif
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
+ifeq ($(shell $(CC) -v 21 | grep -c clang version), 1)
+COMPILER := clang
+else
+COMPILER := gcc
+endif
+export COMPILER
+
 ifeq ($(COMPILER),clang)
 KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
 KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
-- 
2.1.4

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