Re: [PATCH v2] x86/boot: define CC_HAVE_ASM_GOTO

[H. Peter Anvin]

On 09/27/18 13:47, ndesaulniers@xxxxxxxxxx wrote:
> Early prototypes of Clang with asm goto support produce 6 instances of
> the following warning:
> 
> In file included from arch/x86/boot/compressed/misc.h:20:
> In file included from ./include/linux/elf.h:5:
> In file included from ./arch/x86/include/asm/elf.h:8:
> In file included from ./include/linux/thread_info.h:38:
> In file included from ./arch/x86/include/asm/thread_info.h:53:
> ./arch/x86/include/asm/cpufeature.h:150:2: warning: "Compiler lacks
> ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"
> [-W#warnings]
> your compiler arguments"
>  ^
> 
> Since 6 files under arch/x86/boot/compressed/ include
> arch/x86/boot/compressed/misc.h AND
> arch/x86/boot/compressed/Makefile happens to redefine KBUILD_CFLAGS,
> which set these variables in the top level MAKEFILE.
> 

The Right Thing[TM] would probably be to split the CFLAGS into those
that are independent of x86_64 vs i386. After all, there is no
fundamental reason we couldn't want to use asm goto in the setup or
real-mode code in the future.  In addition to BIOS entry code there is
the EFI32 code.

	-hpa