Bug#921267: systemd fails to reach shutdown.target when rebooting or shutting down the system after resuming from suspend

[Michael Biebl]

Control: tags -1 - moreinfo

There has been progress in tracking down the root cause of this issue:
https://github.com/systemd/systemd/issues/11810#issuecomment-489727505

Turns out, RDRAND, which is used to generate uuid's is not stable on
certain AMD processor models after a resume.
This is arguably a firmware/hardware issue and should best be fixed in
the kernel by blacklisting affected CPU models.
https://github.com/systemd/systemd/issues/11810#issuecomment-490275562
suggests that this is specific to AMD CPU family 22, but needs verification.

A fixed kernel for buster seems unlikely at this point, so I wonder
whether we should revert
https://github.com/systemd/systemd/commit/cc83d5197ca08d68fa78167b6a64e9f28da3cc96
i.e. systemd will use getrandom() for uuid generation.

The Debian kernel uses CONFIG_RANDOM_TRUST_CPU=y and it is my
understanding that with CONFIG_RANDOM_TRUST_CPU=y it is less likely that
getrandom() will stall during boot due to missing entropy.

Would welcome input from other team members and Ben, how we should
proceed here for buster.

Regards,
Michael
-- 
Why is it that all of the instruments seeking intelligent life in the
universe are pointed away from Earth?

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