Re: [PATCH] kbuild: let object files depend on recordmcount instead of its sources

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 2011-10-07 at 15:19 +0200, Uwe Kleine-König wrote:
> This has the upside that distributions only have to ship the recordmcount
> binary to allow building modules instead of recordmcount and it's sources.
> 
> Make still notices that the object files need to be rebuilt when
> recordmcount's sources change.

This doesn't work. Try it on a clean build:

  HOSTCC  scripts/basic/fixdep
  GEN     /home/rostedt/work/git/tmp/Makefile
  HOSTCC  scripts/kconfig/conf.o
  SHIPPED scripts/kconfig/zconf.tab.c
  SHIPPED scripts/kconfig/lex.zconf.c
  SHIPPED scripts/kconfig/zconf.hash.c
  HOSTCC  scripts/kconfig/zconf.tab.o
  HOSTLD  scripts/kconfig/conf
scripts/kconfig/conf --silentoldconfig Kconfig
  Using /home/rostedt/work/git/linux-rt.git as source for kernel
  GEN     /home/rostedt/work/git/tmp/Makefile
  CHK     include/linux/version.h
  UPD     include/linux/version.h
  CHK     include/generated/utsrelease.h
  UPD     include/generated/utsrelease.h
  CC      kernel/bounds.s
  GEN     include/generated/bounds.h
  CC      arch/x86/kernel/asm-offsets.s
  GEN     include/generated/asm-offsets.h
  CALL    /home/rostedt/work/git/linux-rt.git/scripts/checksyscalls.sh
make[3]: *** No rule to make target `scripts/mod/empty.o', needed by `scripts/mod/elfconfig.h'.  Stop.
make[2]: *** [scripts/mod] Error 2
make[1]: *** [scripts] Error 2
make: *** [sub-make] Error 2

-- Steve

> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  scripts/Makefile.build |    9 ++++-----
>  1 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index a0fd502..bc83e94 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -271,8 +271,7 @@ sub_cmd_record_mcount =					\
>  	if [ $(@) != "scripts/mod/empty.o" ]; then	\
>  		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
>  	fi;
> -recordmcount_source := $(srctree)/scripts/recordmcount.c \
> -		    $(srctree)/scripts/recordmcount.h
> +recordmcount_exec := $(objtree)/scripts/recordmcount
>  else
>  sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
>  	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
> @@ -280,7 +279,7 @@ sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH
>  	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
>  	"$(LD)" "$(NM)" "$(RM)" "$(MV)" \
>  	"$(if $(part-of-module),1,0)" "$(@)";
> -recordmcount_source := $(srctree)/scripts/recordmcount.pl
> +recordmcount_exec := $(srctree)/scripts/recordmcount.pl
>  endif
>  cmd_record_mcount = 						\
>  	if [ "$(findstring -pg,$(_c_flags))" = "-pg" ]; then	\
> @@ -301,13 +300,13 @@ define rule_cc_o_c
>  endef
>  
>  # Built-in and composite module parts
> -$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
> +$(obj)/%.o: $(src)/%.c $(recordmcount_exec) FORCE
>  	$(call cmd,force_checksrc)
>  	$(call if_changed_rule,cc_o_c)
>  
>  # Single-part modules are special since we need to mark them in $(MODVERDIR)
>  
> -$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
> +$(single-used-m): $(obj)/%.o: $(src)/%.c $(recordmcount_exec) FORCE
>  	$(call cmd,force_checksrc)
>  	$(call if_changed_rule,cc_o_c)
>  	@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)