Re: [PATCH 7/7] kbuild: read *.mod to get objects passed to $(LD) or $(AR)

[Jeff Johnson]

On 4/6/2022 8:30 AM, Masahiro Yamada wrote:
> ld and ar support @file, which command-line options are read from.
>
> Now that *.mod lists the member objects in the correct order, without
> duplication, it is ready to be passed to ld and ar.
>
> By using the @file syntax, people will not be worried about the pitfall
> described in the NOTE.
>
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> ---
>
>   scripts/Makefile.build | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 3da731cf6978..f6a506318795 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -450,22 +450,18 @@ quiet_cmd_ar_lib = AR      $@
>   $(obj)/lib.a: $(lib-y) FORCE
>   	$(call if_changed,ar_lib)
>   
> -# NOTE:
> -# Do not replace $(filter %.o,^) with $(real-prereqs). When a single object
> -# module is turned into a multi object module, $^ will contain header file
> -# dependencies recorded in the .*.cmd file.
>   ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),)
>   quiet_cmd_link_multi-m = AR [M]  $@
>   cmd_link_multi-m =						\
>   	$(cmd_update_lto_symversions);				\
>   	rm -f $@; 						\
> -	$(AR) cDPrsT $@ $(filter %.o,$^)
> +	$(AR) cDPrsT $@ @$(patsubst %.o,%.mod,$@)
>   else
>   quiet_cmd_link_multi-m = LD [M]  $@
> -      cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(filter %.o,$^)
> +      cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@)
>   endif
>   
> -$(multi-obj-m): FORCE
> +$(multi-obj-m): %.o: %.mod FORCE
>   	$(call if_changed,link_multi-m)
>   $(call multi_depend, $(multi-obj-m), .o, -objs -y -m)
>   

Looks like this also addresses the out-of-tree issue described in 
<https://lore.kernel.org/linux-kbuild/1610500731-30960-2-git-send-email-jjohnson@xxxxxxxxxxxxxx/>

:)

/jeff