Messages in this thread Patch in this message | | | Subject | [PATCH v2] arch/x86: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS) | From | John Millikin <> | Date | Sat, 26 Dec 2020 17:41:25 +0900 |
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When cross-compiling with Clang, the `$(CLANG_FLAGS)' variable contains additional flags needed to build C and assembly sources for the target platform. Normally this variable is automatically included in `$(KBUILD_CFLAGS)' by via the top-level Makefile.
The x86 real-mode makefile builds `$(REALMODE_CFLAGS)' from a plain assignment and therefore drops the Clang flags. This causes Clang to not recognize x86-specific assembler directives:
arch/x86/realmode/rm/header.S:36:1: error: unknown directive .type real_mode_header STT_OBJECT ; .size real_mode_header, .-real_mode_header ^
Explicit propagation of `$(CLANG_FLAGS)' to `$(REALMODE_CFLAGS)', which is inherited by real-mode make rules, fixes cross-compilation with Clang for x86 targets.
Relevant flags:
* `--target' sets the target architecture when cross-compiling. This flag must be set for both compilation and assembly (`KBUILD_AFLAGS') to support architecture-specific assembler directives.
* `-no-integrated-as' tells clang to assemble with GNU Assembler instead of its built-in LLVM assembler. This flag is set by default unless `LLVM_IAS=1' is set, because the LLVM assembler can't yet parse certain GNU extensions.
Signed-off-by: John Millikin <john@john-millikin.com> --- Changes in v2: - Reworded the commit message to highlight that this is for cross-compilation. - Removed the `ifdef CONFIG_CC_IS_CLANG' guard.
arch/x86/Makefile | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 7116da3980be..412b849063ec 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -33,6 +33,7 @@ REALMODE_CFLAGS += -ffreestanding REALMODE_CFLAGS += -fno-stack-protector REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4)) +REALMODE_CFLAGS += $(CLANG_FLAGS) export REALMODE_CFLAGS # BITS is used as extension for files which are available in a 32 bit -- 2.29.2
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