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 -- 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
