Re: [PATCH v9 3/3] kbuild: distributed build support for Clang ThinLTO

[Nathan Chancellor]

Hi Rong,

On Tue, Mar 31, 2026 at 03:48:27PM +0000, xur@xxxxxxxxxx wrote:
> diff --git a/Makefile b/Makefile
> index 69ccf9b8507d..26005c64016d 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1047,11 +1047,13 @@ export CC_FLAGS_SCS
>  endif
>  
>  ifdef CONFIG_LTO_CLANG
> -ifdef CONFIG_LTO_CLANG_THIN
> +ifdef CONFIG_LTO_CLANG_FULL
> +CC_FLAGS_LTO	:= -flto
> +else
>  CC_FLAGS_LTO	:= -flto=thin -fsplit-lto-unit
> +if CONFIG_LTO_CLANG_THIN

This should be an 'ifdef', not an 'if'. You copied Yonghong's mistake:

  https://lore.kernel.org/abgRRX3PH9IaExi8@xxxxxxxxxxxxx/
  https://lore.kernel.org/6db3a2f6-d61c-42f1-9b9d-0aca021cc2d7@xxxxxxxxx/

Please slow down and test build your changes before sending them. Each
revision adds four new emails to everyone's inbox, which is just noise
when there are obvious, basic problems. 'b4 diff' shows no actual
difference from v8 and v9, which should have been caught by a simple
build test right before 'git send-email'.

>  KBUILD_LDFLAGS += $(call ld-option,--lto-whole-program-visibility -mllvm -always-rename-promoted-locals=false)
> -else
> -CC_FLAGS_LTO	:= -flto
> +endif
>  endif
>  CC_FLAGS_LTO	+= -fvisibility=hidden
>  
> @@ -1657,6 +1659,7 @@ endif # CONFIG_MODULES
>  CLEAN_FILES += vmlinux.symvers modules-only.symvers \
>  	       modules.builtin modules.builtin.modinfo modules.nsdeps \
>  	       modules.builtin.ranges vmlinux.o.map vmlinux.unstripped \
> +	       vmlinux.thinlto-index builtin.order \
>  	       compile_commands.json rust/test \
>  	       rust-project.json .vmlinux.objs .vmlinux.export.c \
>                 .builtin-dtbs-list .builtin-dtb.S
> @@ -2118,7 +2121,7 @@ clean: $(clean-dirs)
>  	$(call cmd,rmfiles)
>  	@find . $(RCS_FIND_IGNORE) \
>  		\( -name '*.[aios]' -o -name '*.rsi' -o -name '*.ko' -o -name '.*.cmd' \
> -		-o -name '*.ko.*' \
> +		-o -name '*.ko.*' -o -name '*.o.thinlto.bc' \
>  		-o -name '*.dtb' -o -name '*.dtbo' \
>  		-o -name '*.dtb.S' -o -name '*.dtbo.S' \
>  		-o -name '*.dt.yaml' -o -name 'dtbs-list' \

With that addressed above, the series survives my basic LLVM 22.1.2
build test with my distribution configuration. I'll provide formal tags
on a properly tested and fixed revision.

Cheers,
Nathan