diff mbox

Relinking zImage when nothing changes

Message ID 20110812180209.GA28520@merkur.ravnborg.org (mailing list archive)
State New, archived
Headers show

Commit Message

Sam Ravnborg Aug. 12, 2011, 6:02 p.m. UTC
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:

(cut'n'pasted ...)

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.

	Sam
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Comments

Arnaud Lacombe Aug. 12, 2011, 8:20 p.m. UTC | #1
Hi,

On Fri, Aug 12, 2011 at 2:02 PM, Sam Ravnborg <sam@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.

 - Arnaud

>  # We need to prevent any GOTOFF relocs being used with references
>
> (cut'n'pasted ...)
>
> 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.
>
>        Sam
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Sam Ravnborg Aug. 12, 2011, 8:24 p.m. UTC | #2
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@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
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Arnaud Lacombe Aug. 12, 2011, 8:31 p.m. UTC | #3
Hi,

On Fri, Aug 12, 2011 at 4:24 PM, Sam Ravnborg <sam@ravnborg.org> wrote:
> 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@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.
>
oh, indeed. I see your point.

 - Arnaud
--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
diff mbox

Patch

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)

 # We need to prevent any GOTOFF relocs being used with references