Re:New Mac Pro Tech Specs
by vetinari on Friday September 27, 2019 @04:32AM
(#21089708)
There was breaking issue, but it didn't manifest automatically.
It happened, when the 2nd gen TR arrived. It used the same mainboards, so all the manufacturers issued BIOS updates.
Unfortunately, these updates claimed to support SEV (Secure Encrypted Virtualization). Linux of course tried to initialize it at boot/module load time and the entire thing went hanging, because TR CPUs do not support SEV, only EPYCs do.
So there were the following fixes:
1) downgrade BIOS back to pre-TR2 version,
2) blacklist the ccp module; which would make kvm_amd non-functional,
3) wait for a fix in Linux kernel, which initializes SEV with a timeout.
So it wasn't that tragic issue, if you had first gen TR.
It happened, when the 2nd gen TR arrived. It used the same mainboards, so all the manufacturers issued BIOS updates.
Unfortunately, these updates claimed to support SEV (Secure Encrypted Virtualization). Linux of course tried to initialize it at boot/module load time and the entire thing went hanging, because TR CPUs do not support SEV, only EPYCs do.
So there were the following fixes:
1) downgrade BIOS back to pre-TR2 version,
2) blacklist the ccp module; which would make kvm_amd non-functional,
3) wait for a fix in Linux kernel, which initializes SEV with a timeout.
So it wasn't that tragic issue, if you had first gen TR.