[PATCH] ARM: zImage: Skip relinking if nothing changes

[Arnaud Lacombe]

Hi,

On Fri, Aug 12, 2011 at 3:00 PM, Stephen Boyd <sboyd at codeaurora.org> wrote:
> lib1funcs.S is reshipped even though the file hasn't changed
> because the make rule is marked with FORCE. According to Sam
> Ravnborg:
>
>        The FORCE prerequisite will tell make to always execute
>        the command.
>        But we only want to execute the command if:
>        1) $(obj)/lib1funcs.S is missing
>        2) or $(srctree)/arch/$(SRCARCH)/lib/lib1funcs.S is not
>        older then $(obj)/lib1funcs.S
>
>        So dropping FORCE should be a safe thing to do.
>
> This fixes the shipped problem, but we still have to reassemble
> lib1funcs.S because it isn't part of $targets. Add
> lib1funcs.{S,o} to $targets to avoid relinking the compressed
> vmlinux if nothing changes.
>
> Signed-off-by: Stephen Boyd <sboyd at codeaurora.org>
> Acked-by: Sam Ravnborg <sam at ravnborg.org>
> ---
>  arch/arm/boot/compressed/Makefile |    8 +++-----
>  1 files changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
> index 0c74a6f..937fd26 100644
> --- a/arch/arm/boot/compressed/Makefile
> +++ b/arch/arm/boot/compressed/Makefile
> @@ -91,7 +91,7 @@ suffix_$(CONFIG_KERNEL_LZMA) = lzma
>
>  targets       := vmlinux vmlinux.lds \
>                 piggy.$(suffix_y) piggy.$(suffix_y).o \
> -                font.o font.c head.o misc.o $(OBJS)
> +                font.o font.c head.o misc.o lib1funcs.o lib1funcs.S $(OBJS)
>
>  # Make sure files are removed during clean
>  extra-y       += piggy.gzip piggy.lzo piggy.lzma lib1funcs.S
> @@ -121,9 +121,7 @@ LDFLAGS_vmlinux += -X
>  LDFLAGS_vmlinux += -T
>
>  # For __aeabi_uidivmod
> -lib1funcs = $(obj)/lib1funcs.o
> -
> -$(obj)/lib1funcs.S: $(srctree)/arch/$(SRCARCH)/lib/lib1funcs.S FORCE
> +$(obj)/lib1funcs.S: $(srctree)/arch/$(SRCARCH)/lib/lib1funcs.S
>        $(call cmd,shipped)
>
You should be able to avoid the extra copy altogether by doing something ala:

$(obj)/lib1funcs.o: $(srctree)/arch/arm/lib/lib1funcs.S
        $(call cmd,as_o_S)

note that I also remove the $(SRCARCH), as there is no other
`arch/*/lib/lib1funcs.S' than `arch/arm/lib/lib1funcs.S'

 - Arnaud

>  # We need to prevent any GOTOFF relocs being used with references
> @@ -140,7 +138,7 @@ bad_syms=$$($(CROSS_COMPILE)nm $@ | sed -n 's/^.\{8\} [bc] \(.*\)/\1/p') && \
>     echo "$$bad_syms" >&2; rm -f $@; false )
>
>  $(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/$(HEAD) $(obj)/piggy.$(suffix_y).o \
> -               $(addprefix $(obj)/, $(OBJS)) $(lib1funcs) FORCE
> +               $(addprefix $(obj)/, $(OBJS)) $(obj)/lib1funcs.o FORCE
>        $(call if_changed,ld)
>        @$(check_for_bad_syms)
>
> --
> Sent by an employee of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
>
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