On 03/31/2015 06:02 AM, Masahiro Yamada wrote:
Since the Kconfig conversion, some developers have reported that Kbuild sometimes fails completely at random. According to the error reports, it seems to occur for any target board, but only on very fast computers.
The log message for the fail case is like this:
make[1]: *** No rule to make target `../arch//cpu/u-boot.lds', needed by `u-boot.lds'. Stop.
It looks like the top config.mk has not been included for *some* reason, and $(ARCH) has been left blank.
I suspect "autoconf_is_current" is not working in some situation.
That's certainly true. The following code doesn't end up including config.mk in the bad case:
# We want to include arch/$(ARCH)/config.mk only when include/config/auto.conf # is up-to-date. When we switch to a different board configuration, old CONFIG # macros are still remaining in include/config/auto.conf. Without the following # gimmick, wrong config.mk would be included leading nasty warnings/errors. autoconf_is_current := $(if $(wildcard $(KCONFIG_CONFIG)),$(shell find . \ -path ./include/config/auto.conf -newer $(KCONFIG_CONFIG))) ifneq ($(autoconf_is_current),) include $(srctree)/config.mk include $(srctree)/arch/$(ARCH)/Makefile endif
That's because:
[swarren@swarren-lx1 tegra-uboot-flasher]$ ls -l --full-time u-boot-*/{.config,include/config/auto.conf}|cat -rw-rw-r-- 1 swarren swarren 9219 2015-04-01 15:50:08.000000000 -0600 u-boot-bad/.config -rw-rw-r-- 1 swarren swarren 928 2015-04-01 15:50:08.000000000 -0600 u-boot-bad/include/config/auto.conf -rw-rw-r-- 1 swarren swarren 9219 2015-04-01 15:51:25.000000000 -0600 u-boot-ok/.config -rw-rw-r-- 1 swarren swarren 928 2015-04-01 15:51:26.000000000 -0600 u-boot-ok/include/config/auto.conf
In the bad case, the timestamps are equal (and hence the -newer check fails), whereas in the good case they're different. Recall ext* filesystems have a 1s timestamp resolution.
Note that this is state left over from "make xxx_defconfig"; If I just manually run "make all" in a tree in this state, it'll stay in this state forever, and vice-versa for a working tree.
I expect that simulating this condition with some judicious manually executed touch commands would be extremely easy.
Possible solutions are:
Is there a -newer-or-equal that could be used in the find command rather than -newer?
When running "make xxx_defconfig", can the code there compare the timestamp of those two files, and keep looping and touching the auto.conf file until the timestamps differ.
Something else entirely? I couldn't see anything relating to autoconf_is_current in the kernel's makefiles.