[cfarm-users] gcc67/68 back online, please test

[Laurent GUERBY]

Hi,

We just upgraded gcc67/68 to the latest BIOS/AGESA, added some 
settings to BIOS and kernel (see below) and restored ssh access 
to all accounts.

Please test to see if the ryzen machines are at last stable
under cfarm usage patterns.

Note: we had to blacklist ccp kernel module on gcc68
so no kvm there. We'll restore it when new kernel is available
with the proper fix for gcc68 processor.

Sincerely,

Laurent

PS: here are the instructions we followed:
https://utcc.utoronto.ca/~cks/space/blog/linux/RyzenApparentlyStable
For a long time these magic kernel command line parameters and similar
tricks were the only workarounds available, at least to me. However
there had long been rumors of a magic AMD provided magic firmware
option that could work around the problem, generally exposed to you and
me in a BIOS setting called 'Power Supply Idle Control', which you
allegedly wanted to set to 'Typical current idle'. This apparently
became available starting with AGESA 1.0.0.2a, which various
motherboard vendors rolled into their overall BIOS at very different
times. For bonus fun, apparently not all BIOS vendors even expose these
AMD firmware settings, although enthusiast motherboards usually do.

https://utcc.utoronto.ca/~cks/space/blog/linux/KernelRcuNocbsMeaning
rcu_nocbs=0-N processor.max_cstate=1
(where N is the number of CPUs you have minus one.)