Subject: Re: [PATCH] Fix linking modules against crtsavres.o

From: Grant Likely <[email-masked]>
Date: Thu, 16 Oct 2008 09:24:02 -0600

On Thu, Oct 09, 2008 at 09:51:25PM +0200, Bernhard Reutner-Fischer wrote:
> Hi,
> 
> [ http://bugzilla.kernel.org/show_bug.cgi?id=11143 has it all]
> 
> targeting ppc(32), e.g. 405 (!fp), previously i got:
>   CC      drivers/char/hw_random/rng-core.mod.o
>   LD [M]  drivers/char/hw_random/rng-core.ko
> /there/src/buildroot.git.ppc/build_powerpc_nofpu/staging_dir/usr/bin/powerpc-linux-uclibc-ld:
> arch/powerpc/lib/crtsavres.o: No such file: No such file or directory
> 
> 	* Makefile (LDFLAGS_MODULE_PREREQ): New variable to hold prerequisite
> 	files for modules.
> 	* arch/powerpc/Makefile: add crtsavres.o to LDFLAGS_MODULE_PREREQ.
> 	* scripts/Makefile.modpost (cmd_as_o_S): Copy from Makefile.build.
> 	(cmd_ld_ko_o): Also link LDFLAGS_MODULE_PREREQ.
> 	Provide rule to build objects from assembler.
> 
> The attached patch (same as attached to abovementioned bug) fixes this.
> I'm asking the ppc maintainers or you, Sam, to consider something to
> that effect for inclusing in the stable series.
> thanks,

This patch solves the problem for me.  Without it building modules
before the kernel proper fails to find crtsavres.o when linking.

Ben, Paul or Sam, could you please look at this and make comment
if it is the right approach?

I also agree that this should be back ported to the stable series

(Note: for some reason this patch did *not* show up in patchwork).

Cheers,
g.

> Fix linking modules against crtsavres.o
> 
> Previously we got
>   CC      drivers/char/hw_random/rng-core.mod.o
>   LD [M]  drivers/char/hw_random/rng-core.ko
> /there/src/buildroot.git.ppc/build_powerpc_nofpu/staging_dir/usr/bin/powerpc-linux-uclibc-ld: arch/powerpc/lib/crtsavres.o: No such file: No such file or directory
> 
> 	* Makefile (LDFLAGS_MODULE_PREREQ): New variable to hold prerequisite
> 	files for modules.
> 	* arch/powerpc/Makefile: add crtsavres.o to LDFLAGS_MODULE_PREREQ.
> 	* scripts/Makefile.modpost (cmd_as_o_S): Copy from Makefile.build.
> 	(cmd_ld_ko_o): Also link LDFLAGS_MODULE_PREREQ.
> 	Provide rule to build objects from assembler.
> 
> Signed-off-by:  Bernhard Reutner-Fischer  <[email-masked]>
> 
> diff -rup ../../x/linux-2.6.26.5.old/arch/powerpc/Makefile linux-2.6.26.5/arch/powerpc/Makefile
> --- ../../x/linux-2.6.26.5.old/arch/powerpc/Makefile	2008-09-08 19:40:20.000000000 +0200
> +++ linux-2.6.26.5/arch/powerpc/Makefile	2008-10-07 14:28:08.000000000 +0200
> @@ -97,7 +97,7 @@ else
>  	KBUILD_CFLAGS += $(call cc-option,-mtune=power4)
>  endif
>  else
> -LDFLAGS_MODULE	+= arch/powerpc/lib/crtsavres.o
> +LDFLAGS_MODULE_PREREQ += arch/powerpc/lib/crtsavres.o
>  endif
>  
>  ifeq ($(CONFIG_TUNE_CELL),y)
> diff -rup ../../x/linux-2.6.26.5.old/Makefile linux-2.6.26.5/Makefile
> --- ../../x/linux-2.6.26.5.old/Makefile	2008-09-08 19:40:20.000000000 +0200
> +++ linux-2.6.26.5/Makefile	2008-10-07 14:15:59.000000000 +0200
> @@ -318,6 +318,7 @@ MODFLAGS	= -DMODULE
>  CFLAGS_MODULE   = $(MODFLAGS)
>  AFLAGS_MODULE   = $(MODFLAGS)
>  LDFLAGS_MODULE  =
> +LDFLAGS_MODULE_PREREQ  =
>  CFLAGS_KERNEL	=
>  AFLAGS_KERNEL	=
>  
> @@ -342,7 +343,7 @@ KERNELVERSION = $(VERSION).$(PATCHLEVEL)
>  export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
>  export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
>  export CPP AR NM STRIP OBJCOPY OBJDUMP MAKE AWK GENKSYMS PERL UTS_MACHINE
> -export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
> +export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE LDFLAGS_MODULE_PREREQ CHECK CHECKFLAGS
>  
>  export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
>  export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
> diff -rup ../../x/linux-2.6.26.5.old/scripts/Makefile.modpost linux-2.6.26.5/scripts/Makefile.modpost
> --- ../../x/linux-2.6.26.5.old/scripts/Makefile.modpost	2008-09-08 19:40:20.000000000 +0200
> +++ linux-2.6.26.5/scripts/Makefile.modpost	2008-10-07 14:24:34.000000000 +0200
> @@ -122,14 +122,21 @@ quiet_cmd_cc_o_c = CC      $@
>        cmd_cc_o_c = $(CC) $(c_flags) $(CFLAGS_MODULE)	\
>  		   -c -o $@ $<
>  
> -$(modules:.ko=.mod.o): %.mod.o: %.mod.c FORCE
> +quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
> +cmd_as_o_S       = $(CC) $(a_flags) $(AFLAGS_MODULE) -c -o $@ $<
> +
> +$(LDFLAGS_MODULE_PREREQ): %.o: %.S FORCE
> +	$(call if_changed_dep,as_o_S)
> +
> +$(modules:.ko=.mod.o): %.mod.o: %.mod.c $(LDFLAGS_MODULE_PREREQ) FORCE
>  	$(call if_changed_dep,cc_o_c)
>  
>  targets += $(modules:.ko=.mod.o)
>  
>  # Step 6), final link of the modules
>  quiet_cmd_ld_ko_o = LD [M]  $@
> -      cmd_ld_ko_o = $(LD) -r $(LDFLAGS) $(LDFLAGS_MODULE) -o $@		\
> +      cmd_ld_ko_o = $(LD) -r $(LDFLAGS) $(LDFLAGS_MODULE_PREREQ)	\
> +			  $(LDFLAGS_MODULE) -o $@		\
>  			  $(filter-out FORCE,$^)
>  
>  $(modules): %.ko :%.o %.mod.o FORCE

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