Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.

From: vcaputo
Date: Fri Dec 29 2017 - 13:32:52 EST


On Fri, Dec 29, 2017 at 01:18:30PM -0500, Paul Gortmaker wrote:
> [Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] On 29/12/2017 (Fri 10:47) Josh Poimboeuf wrote:
>
> > This seems to be related to a kconfig quirk where only silentoldconfig
> > updates the include/config/auto.conf file. The other config targets
> > (oldconfig, defconfig, etc) don't touch it. It seems intentional, but I
> > have no idea why.
> >
> > That causes the Makefile to get stale data for 'CONFIG_*' variables when
> > it includes auto.conf. So I don't think this is specific to the ORC
> > check. It seems like it could also cause bugs elsewhere.
>
> OK, good - you agree with my initial diagnosis of stale auto.conf then.
> Not sure what Randy was testing when he said he couldn't reproduce it.
>

FWIW just to add another data point, I tripped over this repeatedly
during a recent bisect of v4.14..v4.15-rc4.

My ad-hoc solution was to just delete the stale auto.conf and
reconfigure, IIRC. It was pretty annoying at the time, and I assumed
everyone would be tripping over it so didn't bother making noise on
lkml. Looks like I was mistaken...

Cheers,
Vito Caputo


> > The below (ugly) patch fixes it, though I'm not sure this is the best
> > way to do it. We probably need Masahiro or Michal to chime in here.
>
> Yep, that is why I intentionally put the kbuild folks on the To/Cc of
> the original report (and ran away screaming at the prospect of debugging
> Makefiles on xmas day). But with holidays and all, it might not be
> until early January before they have a chance to reply.
>
> Paul.
> --
>
> >
> > diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> > index 297c1bf35140..3a0d92040a9c 100644
> > --- a/scripts/kconfig/Makefile
> > +++ b/scripts/kconfig/Makefile
> > @@ -21,18 +21,23 @@ unexport CONFIG_
> >
> > xconfig: $(obj)/qconf
> > $< $(silent) $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > gconfig: $(obj)/gconf
> > $< $(silent) $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > menuconfig: $(obj)/mconf
> > $< $(silent) $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > config: $(obj)/conf
> > $< $(silent) --oldaskconfig $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > nconfig: $(obj)/nconf
> > $< $(silent) $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > silentoldconfig: $(obj)/conf
> > $(Q)mkdir -p include/config include/generated
> > @@ -85,6 +90,7 @@ PHONY += $(simple-targets)
> >
> > $(simple-targets): $(obj)/conf
> > $< $(silent) --$@ $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > PHONY += oldnoconfig savedefconfig defconfig
> >
> > @@ -108,9 +114,11 @@ else
> > $(Q)$(MAKE) -f $(srctree)/Makefile $(KBUILD_DEFCONFIG)
> > endif
> > endif
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > %_defconfig: $(obj)/conf
> > $(Q)$< $(silent) --defconfig=arch/$(SRCARCH)/configs/$@ $(Kconfig)
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > configfiles=$(wildcard $(srctree)/kernel/configs/$@ $(srctree)/arch/$(SRCARCH)/configs/$@)
> >
> > @@ -118,6 +126,7 @@ configfiles=$(wildcard $(srctree)/kernel/configs/$@ $(srctree)/arch/$(SRCARCH)/c
> > $(if $(call configfiles),, $(error No configuration exists for this target on this architecture))
> > $(Q)$(CONFIG_SHELL) $(srctree)/scripts/kconfig/merge_config.sh -m .config $(configfiles)
> > +$(Q)yes "" | $(MAKE) -f $(srctree)/Makefile oldconfig
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > PHONY += kvmconfig
> > kvmconfig: kvm_guest.config
> > @@ -130,6 +139,7 @@ xenconfig: xen.config
> > PHONY += tinyconfig
> > tinyconfig:
> > $(Q)$(MAKE) -f $(srctree)/Makefile allnoconfig tiny.config
> > + $(Q)$(MAKE) -f $(srctree)/Makefile silentoldconfig
> >
> > # Help text used by make help
> > help: