There are two solutions or workarounds that have been reliable for me, one of which I now trust more than the other.
First, if your BIOS has the option for 'Power Supply Idle Control' hiding somewhere in its settings (generally in a sub-menu off an 'advanced' menu), setting it to 'Typical current idle' seems to work. I trust this workaround more than the next one, but it requires a BIOS that has been updated to include AGESA 1.0.0.2a (AGESA is apparently a magic blob that AMD supplies to vendors). Before I had the BIOS option available, I also had a stable system by using the kernel command line parameters 'rcu_nocbs=1-15 processor.max_cstate=5' (some people use 1 as the maximum cstate). This requires a kernel that supports rcu_nocbs, which not all kernels are built to do, and is more magical than the BIOS setting; it's clear that these settings are stabilizing the system through some side effects, not their direct operation. (I experimentally determined that on my hardware and setup, merely using 'processor.max_cstate=5' wasn't enough; my machine still locked up.) My machine runs Fedora 27, using Fedora 4.16.x and 4.17.x kernels on a Ryzen 1800X on an ASUS Prime X370-PRO motherboard with ECC RAM, currently using BIOS 4011. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1690085 Title: Ryzen 1800X freeze - rcu_sched detected stalls on CPUs/tasks To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1690085/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
