Ping: [PATCH 1/9] build: use if_changed more consistently (and correctly) for prelink*.o

[Jan Beulich <jbeulich@xxxxxxxx>]

On 14.09.2020 12:15, Jan Beulich wrote:
> Switch to $(call if_changed,ld) where possible; presumably not doing so
> in e321576f4047 ("xen/build: start using if_changed") right away was an
> oversight, as it did for Arm in (just) one case. It failed to add
> prelink.o to $(targets), though, causing - judging from the observed
> behavior on x86 - undue rebuilds of the final binary (because of
> prelink.o getting rebuild for $(cmd_prelink.o) being empty, in turn
> because of .prelink.o.cmd not getting read) during "make install-xen".
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
>  xen/arch/arm/Makefile |  4 +++-
>  xen/arch/x86/Makefile | 18 ++++++++++--------
>  2 files changed, 13 insertions(+), 9 deletions(-)

May I ask for an Arm-side ack (or otherwise) here, please?

Jan

> diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
> index 51173d97127e..296c5e68bbc3 100644
> --- a/xen/arch/arm/Makefile
> +++ b/xen/arch/arm/Makefile
> @@ -95,12 +95,14 @@ prelink_lto.o: $(ALL_OBJS)
>  
>  # Link it with all the binary objects
>  prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) 
> prelink_lto.o
> -     $(LD) $(XEN_LDFLAGS) -r -o $@ $^
> +     $(call if_changed,ld)
>  else
>  prelink.o: $(ALL_OBJS) FORCE
>       $(call if_changed,ld)
>  endif
>  
> +targets += prelink.o
> +
>  $(TARGET)-syms: prelink.o xen.lds
>       $(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o \
>           $(BASEDIR)/common/symbols-dummy.o -o $(@D)/.$(@F).0
> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> index 74152f2a0dad..9b368632fb43 100644
> --- a/xen/arch/x86/Makefile
> +++ b/xen/arch/x86/Makefile
> @@ -136,19 +136,21 @@ prelink_lto.o: $(ALL_OBJS)
>       $(LD_LTO) -r -o $@ $^
>  
>  # Link it with all the binary objects
> -prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) 
> prelink_lto.o $(EFI_OBJS-y)
> -     $(LD) $(XEN_LDFLAGS) -r -o $@ $^
> +prelink.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) 
> prelink_lto.o $(EFI_OBJS-y) FORCE
> +     $(call if_changed,ld)
>  
> -prelink-efi.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) 
> prelink_lto.o
> -     $(LD) $(XEN_LDFLAGS) -r -o $@ $^
> +prelink-efi.o: $(patsubst %/built_in.o,%/built_in_bin.o,$(ALL_OBJS)) 
> prelink_lto.o FORCE
> +     $(call if_changed,ld)
>  else
> -prelink.o: $(ALL_OBJS) $(EFI_OBJS-y)
> -     $(LD) $(XEN_LDFLAGS) -r -o $@ $^
> +prelink.o: $(ALL_OBJS) $(EFI_OBJS-y) FORCE
> +     $(call if_changed,ld)
>  
> -prelink-efi.o: $(ALL_OBJS)
> -     $(LD) $(XEN_LDFLAGS) -r -o $@ $^
> +prelink-efi.o: $(ALL_OBJS) FORCE
> +     $(call if_changed,ld)
>  endif
>  
> +targets += prelink.o prelink-efi.o
> +
>  $(TARGET)-syms: prelink.o xen.lds
>       $(LD) $(XEN_LDFLAGS) -T xen.lds -N prelink.o $(build_id_linker) \
>           $(BASEDIR)/common/symbols-dummy.o -o $(@D)/.$(@F).0
>