Relinking zImage when nothing changes

[Sam Ravnborg]

On Fri, Aug 12, 2011 at 04:20:15PM -0400, Arnaud Lacombe wrote:
> Hi,
> 
> On Fri, Aug 12, 2011 at 2:02 PM, Sam Ravnborg <sam at ravnborg.org> wrote:
> > On Fri, Aug 12, 2011 at 10:46:24AM -0700, Stephen Boyd wrote:
> >> I was hoping with the recent patch e78e8f2 (kernel: prevent unnecessary
> >> rebuilding due to config_data.gz, 2011-07-05) compiling ARM linux a
> >> second time would amount to no more linking. This doesn't seem to be the
> >> case though. Doing a make V=2 I see that lib1funcs.S is shipped and thus
> >> we have to recompile it although nothing actually changed. This in turn
> >> requires us to relink the compressed vmlinux and then recreate the zImage.
> >>
> >>   Kernel: arch/arm/boot/Image is ready
> >>   SHIPPED arch/arm/boot/compressed/lib1funcs.S - due to missing .cmd file
> >>   AS      arch/arm/boot/compressed/lib1funcs.o - due to: arch/arm/boot/compressed/lib1funcs.S
> >>   LD      arch/arm/boot/compressed/vmlinux - due to: arch/arm/boot/compressed/lib1funcs.o
> >>   OBJCOPY arch/arm/boot/zImage - due to: arch/arm/boot/compressed/vmlinux
> >>   Kernel: arch/arm/boot/zImage is ready
> >>
> >>
> >> Is there any way to avoid this? Perhaps the shipped command could become
> >> a bit wiser?
> >
> > Following patch will likely fix it:
> > diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
> > index 0c74a6f..80b6b6e 100644
> > --- a/arch/arm/boot/compressed/Makefile
> > +++ b/arch/arm/boot/compressed/Makefile
> > @@ -123,7 +123,7 @@ 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)
> >
> AFAIK, we have a generic rule to handle shipped files:
> 
> from scripts/Makefile.lib:
> 
> $(obj)/%: $(src)/%_shipped
>         $(call cmd,shipped)
> 
> so, that rule should not be needed at all.

In this case the cmd_shipped is misused to make a copy of a file.
So the generic rule does not apply.

	Sam