Messages in this thread Patch in this message | | | From | Nathan Chancellor <> | Subject | [PATCH] x86/boot/compressed: Move CLANG_FLAGS to beginning of KBUILD_CFLAGS | Date | Tue, 21 Dec 2021 17:52:45 -0700 |
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When cross compiling i386_defconfig on an arm64 host with clang, there are a few instances of '-Waddress-of-packed-member' and '-Wgnu-variable-sized-type-not-at-end' in arch/x86/boot/compressed/, which should both be disabled with the cc-disable-warning calls in that directory's Makefile, which indicates that cc-disable-warning is failing at the point of testing these flags.
The cc-disable-warning calls fail because at the point that the flags are tested, KBUILD_CFLAGS has '-march=i386' without $(CLANG_FLAGS), which has the '--target=' flag to tell clang what architecture it is targeting. Without the '--target=' flag, the host architecture (arm64) is used and i386 is not a valid value for '-march=' in that case. This error can be seen by adding some logging to try-run:
clang-14: error: the clang compiler does not support '-march=i386'
Invoking the compiler has to succeed prior to calling cc-option or cc-disable-warning in order to accurately test whether or not the flag is supported; if it doesn't, the requested flag can never be added to the compiler flags. Move $(CLANG_FLAGS) to the beginning of KBUILD_FLAGS so that any new flags that might be added in the future can be accurately tested.
Fixes: d5cbd80e302d ("x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGS") Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- arch/x86/boot/compressed/Makefile | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 431bf7f846c3..169186dba1d7 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -28,7 +28,7 @@ KCOV_INSTRUMENT := n targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4 vmlinux.bin.zst -KBUILD_CFLAGS := -m$(BITS) -O2 +KBUILD_CFLAGS := -m$(BITS) -O2 $(CLANG_FLAGS) KBUILD_CFLAGS += -fno-strict-aliasing -fPIE KBUILD_CFLAGS += -Wundef KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING @@ -47,7 +47,6 @@ KBUILD_CFLAGS += -D__DISABLE_EXPORTS # Disable relocation relaxation in case the link is not PIE. KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mrelax-relocations=no) KBUILD_CFLAGS += -include $(srctree)/include/linux/hidden.h -KBUILD_CFLAGS += $(CLANG_FLAGS) # sev.c indirectly inludes inat-table.h which is generated during # compilation and stored in $(objtree). Add the directory to the includes so base-commit: 2f47a9a4dfa3674fad19a49b40c5103a9a8e1589 -- 2.34.1
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