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