/etc/init.d/rngd and /etc/conf.d/rngd both refer to and may use the no-tpm and no-drng options. In version 6 of rngd, those 2 options are no longer available. Thus setting NO_TPM=1 or NO_DRNG=1 in /etc/conf.d/rngd will cause /etc/init.d/rngd to fail to start.
I've hit the same issue with sys-apps/rng-tools-6.1 (the most recent version currently in the Portage tree).
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=2a5ab18f1a74b1d1e59e5d45ee425da8808eb289 commit 2a5ab18f1a74b1d1e59e5d45ee425da8808eb289 Author: Göktürk Yüksek <gokturk@gentoo.org> AuthorDate: 2017-10-26 01:05:05 +0000 Commit: Göktürk Yüksek <gokturk@gentoo.org> CommitDate: 2017-10-26 01:05:37 +0000 sys-apps/rng-tools: add support for NP_TPM and NO_DRNG options in v6 rng-tools-6 removes the command line options '--no-tpm' and '--no-drng'. Instead, it allows the inclusion and exclusion of a particular entropy source using the command line options '-n' and 'x' respectively. Maintain backwards compatibility by translating the NP_TPM and NO_DRNG options in the conf file to exclusion options. Closes: https://bugs.gentoo.org/630798 Package-Manager: Portage-2.3.8, Repoman-2.3.2 sys-apps/rng-tools/files/rngd-initd-6 | 16 ++++++++++++++++ .../{rng-tools-6.ebuild => rng-tools-6-r1.ebuild} | 2 +- .../{rng-tools-6.1.ebuild => rng-tools-6.1-r1.ebuild} | 2 +- 3 files changed, 18 insertions(+), 2 deletions(-)