cgroup_bpf patch is applied towards kernel 4.10 and up https://github.com/systemd/systemd/issues/7188 kernel 4.9 doesn't have this functionality, therefore >=systemd-235 should require kernel >=4.10 or backport the cgroup_bpf patch to lts kernels
cgroup bpf support is not a requirement; it's just a warning. Lennart has already fixed the log spam issue on master.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=663c5cf752b24425fa93c8f9a0fbf22077314520 commit 663c5cf752b24425fa93c8f9a0fbf22077314520 Author: Mike Gilbert <floppym@gentoo.org> AuthorDate: 2017-11-27 22:03:07 +0000 Commit: Mike Gilbert <floppym@gentoo.org> CommitDate: 2017-11-27 22:03:59 +0000 sys-apps/systemd: add kernel check for CGROUP_BPF Closes: https://bugs.gentoo.org/638860 Package-Manager: Portage-2.3.15, Repoman-2.3.6_p7 sys-apps/systemd/systemd-235-r1.ebuild | 1 + sys-apps/systemd/systemd-9999.ebuild | 1 + 2 files changed, 2 insertions(+)