kernel/built-in.o: In function `update_wall_time': (.text+0x697a4): undefined reference to `____ilog2_NaN' http://package18.nyi.freebsd.org/data/103amd64-default-PR222542/2017-10-11_07h07m20s/logs/errors/linux-kernel-4.9.5_1.log http://package18.nyi.freebsd.org/data/103i386-default-PR222542/2017-10-10_18h48m24s/logs/errors/linux-kernel-4.9.5_1.log
To reproduce before build do: $ echo "DEFAULT_VERSIONS += gcc=7" >>${__MAKE_CONF:-/etc/make.conf}
Apparently this commit resolves it: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=474c90156c8dcc2fa815e6716cc9394d7930cb9c Will test later.
A commit references this bug: Author: tobik Date: Fri Oct 13 14:39:18 UTC 2017 New revision: 452006 URL: https://svnweb.freebsd.org/changeset/ports/452006 Log: devel/linux-kernel: Fix build with lang/gcc7 or later PR: 222961 Reported by: jbeich Obtained from: upstream Changes: head/devel/linux-kernel/Makefile head/devel/linux-kernel/files/patch-gcc7