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selftests: Fix clang cross compilation

PATCH In review Mark Brown 2 participants 2 messages Jun 14, 2022 Kselftest

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Mark Brown

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#0 lore raw

PATCH 1/1 selftests: Fix clang cross compilation

Unlike GCC clang uses a single compiler image to support multiple target architectures meaning that we can't simply rely on CROSS_COMPILE to select the output architecture. Instead we must pass --target to the compiler to tell it what to output, kselftest was not doing this so cross compilation of kselftest using clang resulted in kselftest being built for the host architecture.

More work is required to fix tests using custom rules but this gets the bulk of things building.

Signed-off-by Mark Brown <[email protected]>
---
 tools/testing/selftests/lib.mk | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)
tools/testing/selftests/lib.mk +23 -2
index 2a2d240cdc1b..1a5cc3cd97ec 100644
@@ -7,10 +7,31 @@ else ifneq ($(filter -%,$(LLVM)),)
 LLVM_SUFFIX := $(LLVM)
 endif
 
-CC := $(LLVM_PREFIX)clang$(LLVM_SUFFIX)
+CLANG_TARGET_FLAGS_arm          := arm-linux-gnueabi
+CLANG_TARGET_FLAGS_arm64        := aarch64-linux-gnu
+CLANG_TARGET_FLAGS_hexagon      := hexagon-linux-musl
+CLANG_TARGET_FLAGS_m68k         := m68k-linux-gnu
+CLANG_TARGET_FLAGS_mips         := mipsel-linux-gnu
+CLANG_TARGET_FLAGS_powerpc      := powerpc64le-linux-gnu
+CLANG_TARGET_FLAGS_riscv        := riscv64-linux-gnu
+CLANG_TARGET_FLAGS_s390         := s390x-linux-gnu
+CLANG_TARGET_FLAGS_x86          := x86_64-linux-gnu
+CLANG_TARGET_FLAGS              := $(CLANG_TARGET_FLAGS_$(ARCH))
+
+ifeq ($(CROSS_COMPILE),)
+ifeq ($(CLANG_TARGET_FLAGS),)
+$(error Specify CROSS_COMPILE or add '--target=' option to lib.mk
+else
+CLANG_FLAGS     += --target=$(CLANG_TARGET_FLAGS)
+endif # CLANG_TARGET_FLAGS
+else
+CLANG_FLAGS     += --target=$(notdir $(CROSS_COMPILE:%-=%))
+endif # CROSS_COMPILE
+
+CC := $(LLVM_PREFIX)clang$(LLVM_SUFFIX) $(CLANG_FLAGS) -fintegrated-as
 else
 CC := $(CROSS_COMPILE)gcc
-endif
+endif # LLVM
 
 ifeq (0,$(MAKELEVEL))
     ifeq ($(OUTPUT),)
Signature · 1 line
2.30.2
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#1 lore raw
Quoted 7 lines · Mark Brown

Unlike GCC clang uses a single compiler image to support multiple target architectures meaning that we can't simply rely on CROSS_COMPILE to select the output architecture. Instead we must pass --target to the compiler to tell it what to output, kselftest was not doing this so cross compilation of kselftest using clang resulted in kselftest being built for the host architecture.

Quoted 8 lines

More work is required to fix tests using custom rules but this gets the bulk of things building.

Signed-off-by Mark Brown <[email protected]>
---
  tools/testing/selftests/lib.mk | 25 +++++++++++++++++++++++--
  1 file changed, 23 insertions(+), 2 deletions(-)

Thank you. I will apply this for the next rc.

thanks,
-- Shuah