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Date:   Wed, 11 Sep 2019 11:20:49 -0700
From:   Nathan Chancellor <>
To:     Benjamin Herrenschmidt <>,
        Paul Mackerras <>,
        Michael Ellerman <>
        Nick Desaulniers <>,
        Nathan Chancellor <>,
        Daniel Axtens <>
Subject: [PATCH v3 1/3] powerpc: Don't add -mabi= flags when building with Clang

When building pseries_defconfig, building vdso32 errors out:

  error: unknown target ABI 'elfv1'

This happens because -m32 in clang changes the target to 32-bit,
which does not allow the ABI to be changed, as the setABI virtual
function is not overridden:

Commit 4dc831aa8813 ("powerpc: Fix compiling a BE kernel with a
powerpc64le toolchain") added these flags to fix building big endian
kernels with a little endian GCC.

Clang doesn't need -mabi because the target triple controls the default
value. -mlittle-endian and -mbig-endian manipulate the triple into
either powerpc64-* or powerpc64le-*, which properly sets the default

Adding a debug print out in the PPC64TargetInfo constructor after line
383 above shows this:

$ echo | ./clang -E --target=powerpc64-linux -mbig-endian -o /dev/null -
Default ABI: elfv1

$ echo | ./clang -E --target=powerpc64-linux -mlittle-endian -o /dev/null -
Default ABI: elfv2

$ echo | ./clang -E --target=powerpc64le-linux -mbig-endian -o /dev/null -
Default ABI: elfv1

$ echo | ./clang -E --target=powerpc64le-linux -mlittle-endian -o /dev/null -
Default ABI: elfv2

Don't specify -mabi when building with clang to avoid the build error
with -m32 and not change any code generation.

-mcall-aixdesc is not an implemented flag in clang so it can be
safely excluded as well, see commit 238abecde8ad ("powerpc: Don't
use gcc specific options on clang").

pseries_defconfig successfully builds after this patch and
powernv_defconfig and ppc44x_defconfig don't regress.

Reviewed-by: Daniel Axtens <>
Signed-off-by: Nathan Chancellor <>

v1 -> v2:

* Improve commit message

v2 -> v3:

* Rebase and merge into a single series.

 arch/powerpc/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 46ed198a3aa3..150925a2e06e 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -93,11 +93,13 @@ MULTIPLEWORD	:= -mmultiple
 ifdef CONFIG_PPC64
 cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
 cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mcall-aixdesc)
 aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mabi=elfv2
   cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mno-strict-align
@@ -143,6 +145,7 @@ endif
 CFLAGS-$(CONFIG_PPC64)	:= $(call cc-option,-mtraceback=no)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2,$(call cc-option,-mcall-aixdesc))
 AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2)
@@ -151,6 +154,7 @@ CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcall-aixdesc)
 AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcmodel=medium,$(call cc-option,-mminimal-toc))
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mno-pointers-to-nested-functions)

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