Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
On Mon, Dec 17, 2018 at 6:45 AM Paul Gortmaker wrote: > > [Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] > On 29/12/2017 (Fri 13:18) 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. > > > > > 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. > > It is nearly a year later and we still have this false positive. > > paul@sm:~/git/linux-head$ make -j12 > /dev/null > Makefile:966: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, > please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. > paul@sm:~/git/linux-head$ grep UNWINDER_ORC .config > # CONFIG_UNWINDER_ORC is not set > > We do know a bit more now -- the auto.conf issue has been independently > confirmed and "fixed" for other subsystems/issues since, like RETPOLINE: > > - > commit 25896d073d8a0403b07e6dec56f58e6c33678207 > Author: Masahiro Yamada > Date: Wed Dec 5 15:27:19 2018 +0900 > > x86/build: Fix compiler support check for CONFIG_RETPOLINE > > It is troublesome to add a diagnostic like this to the Makefile > parse stage because the top-level Makefile could be parsed with > a stale include/config/auto.conf. > > Once you are hit by the error about non-retpoline compiler, the > compilation still breaks even after disabling CONFIG_RETPOLINE. > - > > I'm not sure if we want to treat this on a per config option each time > again and again, or undertake a more global kbuild approach, but it does > warrant a mention and a re-examination before we "solve" this again. I did not notice this thread (perhaps, it fell into my crack during the holidays) but I actually tried to fix this twice in a sophisticated way in the past. The first attempt (https://patchwork.kernel.org/patch/10516049/) was rejected by Josh Poimboeuf. The second one (https://patchwork.kernel.org/patch/10643245/) turned out not working as expected. Now, I am preparing for the third attempt, but it will take time for review. What I can do now is the similar fix-up as commit 25896d073d8. I will post a cheesy fix-up patch. -- Best Regards Masahiro Yamada
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
[Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] On 29/12/2017 (Fri 13:18) 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. > > > 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. It is nearly a year later and we still have this false positive. paul@sm:~/git/linux-head$ make -j12 > /dev/null Makefile:966: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. paul@sm:~/git/linux-head$ grep UNWINDER_ORC .config # CONFIG_UNWINDER_ORC is not set We do know a bit more now -- the auto.conf issue has been independently confirmed and "fixed" for other subsystems/issues since, like RETPOLINE: - commit 25896d073d8a0403b07e6dec56f58e6c33678207 Author: Masahiro Yamada Date: Wed Dec 5 15:27:19 2018 +0900 x86/build: Fix compiler support check for CONFIG_RETPOLINE It is troublesome to add a diagnostic like this to the Makefile parse stage because the top-level Makefile could be parsed with a stale include/config/auto.conf. Once you are hit by the error about non-retpoline compiler, the compilation still breaks even after disabling CONFIG_RETPOLINE. - I'm not sure if we want to treat this on a per config option each time again and again, or undertake a more global kbuild approach, but it does warrant a mention and a re-examination before we "solve" this again. Paul. --
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
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:
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
[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. > 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:
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
On Thu, Dec 28, 2017 at 09:13:24PM -0500, Paul Gortmaker wrote: > > > There is a regression new to 4.15 that happens in a rather common > > > workflow which results in the frustrating situation where the user has > > > clearly disabled UNWINDER_ORC in their ".config" file, and yet they > > > still get the immediate false error saying they need libelf-dev since > > > "CONFIG_UNWINDER_ORC=y" is still set, and hence they can not build. > > > > > > The regression requires UNWINDER_ORC=y (now the default in commit > > > fc72ae40e303) followed by the user subsequently disabling it, which is > > > common if the user doesn't have libelf-dev and doesn't care about ORC. > > > > > > This happens because the recently added test in the top level Makefile > > > assumes that ,config data will be mapped into include/config/auto.conf > > > either by the end user running "make oldconfig" or the Makefile itself > > > detecting that "silentoldconfig" should be run. As the simple > > > reproducer below shows, this clearly does not happen as expected. 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. 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. 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:
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
[Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.] On 28/12/2017 (Thu 11:29) Randy Dunlap wrote: > On 12/25/2017 08:30 PM, Paul Gortmaker wrote: > > There is a regression new to 4.15 that happens in a rather common > > workflow which results in the frustrating situation where the user has > > clearly disabled UNWINDER_ORC in their ".config" file, and yet they > > still get the immediate false error saying they need libelf-dev since > > "CONFIG_UNWINDER_ORC=y" is still set, and hence they can not build. > > > > The regression requires UNWINDER_ORC=y (now the default in commit > > fc72ae40e303) followed by the user subsequently disabling it, which is > > common if the user doesn't have libelf-dev and doesn't care about ORC. > > > > This happens because the recently added test in the top level Makefile > > assumes that ,config data will be mapped into include/config/auto.conf > > either by the end user running "make oldconfig" or the Makefile itself > > detecting that "silentoldconfig" should be run. As the simple > > reproducer below shows, this clearly does not happen as expected. > > > > Note that the test for CONFIG_STACK_VALIDATION and libelf-dev in the > > same place in the Makefile is broken in the same way, but since it is a > > warning and not an error, nobody cared about the bogus false positives. > > Yeah, that's odd. > > > Since there is no way I'm going to debug Makefile stuff on Christmas > > Day, I figured that I should at least report it intstead. The work > > around is to save your .config and run a "make distclean" or manually > > clobber the stale include/config/auto.conf or similar. But a frustrated > > user wouldn't know that w/o the root cause... > > > > I have tried to reproduce this multiple times but cannot do so. > It remains with: > > > grep UNWINDER .config > # CONFIG_UNWINDER_ORC is not set > CONFIG_UNWINDER_FRAME_POINTER=y As it should. Please re-read the reproducer and the above. The data in the .config is exactly as it should be. The include/config/auto.conf having stale data with ORC still listed as enabled is the issue. Also note you need a machine with libelf-dev not installed, at the risk of stating the obvious. Paul. -- > > > > > - reproducer > > > > paul@gw:~/git/linux-head$ git describe > > v4.15-rc5 > > paul@gw:~/git/linux-head$ make distclean > > paul@gw:~/git/linux-head$ make defconfig > > HOSTCC scripts/basic/fixdep > > HOSTCC scripts/kconfig/conf.o > > SHIPPED scripts/kconfig/zconf.tab.c > > SHIPPED scripts/kconfig/zconf.lex.c > > HOSTCC scripts/kconfig/zconf.tab.o > > HOSTLD scripts/kconfig/conf > > *** Default configuration is based on 'x86_64_defconfig' > > # > > # configuration written to .config > > # > > paul@gw:~/git/linux-head$ make > > scripts/kconfig/conf --silentoldconfig Kconfig > > Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, > > please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. > > paul@gw:~/git/linux-head$ vi .config # disable ORC in favour of > > FRAME_POINTER > > paul@gw:~/git/linux-head$ make oldconfig > > scripts/kconfig/conf --oldconfig Kconfig > > # > > # configuration written to .config > > # > > paul@gw:~/git/linux-head$ grep UNWINDER .config > > # CONFIG_UNWINDER_ORC is not set > > CONFIG_UNWINDER_FRAME_POINTER=y > > paul@gw:~/git/linux-head$ make > > Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, > > please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. > > paul@gw:~/git/linux-head$ ls -l .config include/config/auto.conf > > -rw-rw-r-- 1 paul paul 115953 Dec 25 22:48 .config > > -rw-rw-r-- 1 paul paul 33069 Dec 25 22:46 include/config/auto.conf > > paul@gw:~/git/linux-head$ grep UNWINDER include/config/auto.conf > > CONFIG_UNWINDER_ORC=y > > paul@gw:~/git/linux-head$ > > > > - reproducer > > > -- > ~Randy
Re: [Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
On 12/25/2017 08:30 PM, Paul Gortmaker wrote: > There is a regression new to 4.15 that happens in a rather common > workflow which results in the frustrating situation where the user has > clearly disabled UNWINDER_ORC in their ".config" file, and yet they > still get the immediate false error saying they need libelf-dev since > "CONFIG_UNWINDER_ORC=y" is still set, and hence they can not build. > > The regression requires UNWINDER_ORC=y (now the default in commit > fc72ae40e303) followed by the user subsequently disabling it, which is > common if the user doesn't have libelf-dev and doesn't care about ORC. > > This happens because the recently added test in the top level Makefile > assumes that ,config data will be mapped into include/config/auto.conf > either by the end user running "make oldconfig" or the Makefile itself > detecting that "silentoldconfig" should be run. As the simple > reproducer below shows, this clearly does not happen as expected. > > Note that the test for CONFIG_STACK_VALIDATION and libelf-dev in the > same place in the Makefile is broken in the same way, but since it is a > warning and not an error, nobody cared about the bogus false positives. Yeah, that's odd. > Since there is no way I'm going to debug Makefile stuff on Christmas > Day, I figured that I should at least report it intstead. The work > around is to save your .config and run a "make distclean" or manually > clobber the stale include/config/auto.conf or similar. But a frustrated > user wouldn't know that w/o the root cause... > I have tried to reproduce this multiple times but cannot do so. It remains with: > grep UNWINDER .config # CONFIG_UNWINDER_ORC is not set CONFIG_UNWINDER_FRAME_POINTER=y > > - reproducer > > paul@gw:~/git/linux-head$ git describe > v4.15-rc5 > paul@gw:~/git/linux-head$ make distclean > paul@gw:~/git/linux-head$ make defconfig > HOSTCC scripts/basic/fixdep > HOSTCC scripts/kconfig/conf.o > SHIPPED scripts/kconfig/zconf.tab.c > SHIPPED scripts/kconfig/zconf.lex.c > HOSTCC scripts/kconfig/zconf.tab.o > HOSTLD scripts/kconfig/conf > *** Default configuration is based on 'x86_64_defconfig' > # > # configuration written to .config > # > paul@gw:~/git/linux-head$ make > scripts/kconfig/conf --silentoldconfig Kconfig > Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, > please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. > paul@gw:~/git/linux-head$ vi .config # disable ORC in favour of FRAME_POINTER > paul@gw:~/git/linux-head$ make oldconfig > scripts/kconfig/conf --oldconfig Kconfig > # > # configuration written to .config > # > paul@gw:~/git/linux-head$ grep UNWINDER .config > # CONFIG_UNWINDER_ORC is not set > CONFIG_UNWINDER_FRAME_POINTER=y > paul@gw:~/git/linux-head$ make > Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, > please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. > paul@gw:~/git/linux-head$ ls -l .config include/config/auto.conf > -rw-rw-r-- 1 paul paul 115953 Dec 25 22:48 .config > -rw-rw-r-- 1 paul paul 33069 Dec 25 22:46 include/config/auto.conf > paul@gw:~/git/linux-head$ grep UNWINDER include/config/auto.conf > CONFIG_UNWINDER_ORC=y > paul@gw:~/git/linux-head$ > > - reproducer -- ~Randy
[Regression 4.15] Can't kill CONFIG_UNWINDER_ORC with fire or plague.
There is a regression new to 4.15 that happens in a rather common workflow which results in the frustrating situation where the user has clearly disabled UNWINDER_ORC in their ".config" file, and yet they still get the immediate false error saying they need libelf-dev since "CONFIG_UNWINDER_ORC=y" is still set, and hence they can not build. The regression requires UNWINDER_ORC=y (now the default in commit fc72ae40e303) followed by the user subsequently disabling it, which is common if the user doesn't have libelf-dev and doesn't care about ORC. This happens because the recently added test in the top level Makefile assumes that ,config data will be mapped into include/config/auto.conf either by the end user running "make oldconfig" or the Makefile itself detecting that "silentoldconfig" should be run. As the simple reproducer below shows, this clearly does not happen as expected. Note that the test for CONFIG_STACK_VALIDATION and libelf-dev in the same place in the Makefile is broken in the same way, but since it is a warning and not an error, nobody cared about the bogus false positives. Since there is no way I'm going to debug Makefile stuff on Christmas Day, I figured that I should at least report it intstead. The work around is to save your .config and run a "make distclean" or manually clobber the stale include/config/auto.conf or similar. But a frustrated user wouldn't know that w/o the root cause... - reproducer paul@gw:~/git/linux-head$ git describe v4.15-rc5 paul@gw:~/git/linux-head$ make distclean paul@gw:~/git/linux-head$ make defconfig HOSTCC scripts/basic/fixdep HOSTCC scripts/kconfig/conf.o SHIPPED scripts/kconfig/zconf.tab.c SHIPPED scripts/kconfig/zconf.lex.c HOSTCC scripts/kconfig/zconf.tab.o HOSTLD scripts/kconfig/conf *** Default configuration is based on 'x86_64_defconfig' # # configuration written to .config # paul@gw:~/git/linux-head$ make scripts/kconfig/conf --silentoldconfig Kconfig Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. paul@gw:~/git/linux-head$ vi .config # disable ORC in favour of FRAME_POINTER paul@gw:~/git/linux-head$ make oldconfig scripts/kconfig/conf --oldconfig Kconfig # # configuration written to .config # paul@gw:~/git/linux-head$ grep UNWINDER .config # CONFIG_UNWINDER_ORC is not set CONFIG_UNWINDER_FRAME_POINTER=y paul@gw:~/git/linux-head$ make Makefile:926: *** "Cannot generate ORC metadata for CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or elfutils-libelf-devel". Stop. paul@gw:~/git/linux-head$ ls -l .config include/config/auto.conf -rw-rw-r-- 1 paul paul 115953 Dec 25 22:48 .config -rw-rw-r-- 1 paul paul 33069 Dec 25 22:46 include/config/auto.conf paul@gw:~/git/linux-head$ grep UNWINDER include/config/auto.conf CONFIG_UNWINDER_ORC=y paul@gw:~/git/linux-head$ - reproducer