Ryzen
Enable microcode support
Install the amd-ucode package to enable microcode updates and enable it with the help of the Microcode page. These updates provide bug fixes that can be critical to the stability of your system. It is highly recommended to use it despite it being proprietary.
Tweaking Ryzen
Power/temperature monitoring
lm_sensors should be able to monitor temperatures out of the box. However, for more detailed information such as power consumption and voltage, zenpower-dkmsAUR is needed. For GUI based monitoring tools, use zenmonitorAUR or zenmonitor3-gitAUR for Zen 3 CPUs.
Power managing
- RyzenAdj — RyzenAdj is a command-line tool that can adjust power management settings for Ryzen mobile processors.
- Ryzen Controller — Ryzen Controller is a GUI for RyzenAdj.
Overclocking
zenstates-gitAUR (CLI) is a tool made by r4m0n to adjust the clock speed and voltage. A detailed example was given in Level1Techs' forums by catsay for you to understand it.
Compiling a kernel
See Gentoo:Ryzen#Kernel on enabling Ryzen support.
Troubleshooting
Random reboots
See Gentoo:Ryzen#Random_reboots_with_mce_events if you are experiencing random reboots.
With Ryzen 5, particularly the enthusiast models of 5950X and 5900X there seem to be some slight instability issues under Linux, related possibly to the 5.11+ kernel, as shown by this kernel bug. After investigating and reading reports on the Internet I discovered that out of the box, Windows seems to run the CPUs at higher voltage and lower peak frequencies, compared to the stock linux kernel, which depending on your draw from the silicone lottery could cause a host of random application crashes or hardware errors that lead to reboots. You will recognise those by dmesg logs that look like:
kernel: mce: [Hardware Error]: Machine check events logged kernel: mce: [Hardware Error]: CPU 22: Machine Check: 0 Bank 1: bc800800060c0859 lightbringer kernel: mce: [Hardware Error]: TSC 0 ADDR 7ea8f5b00 MISC d012000000000000 IPID 100b000000000 lightbringer kernel: mce: [Hardware Error]: PROCESSOR 2:a20f10 TIME 1636645367 SOCKET 0 APIC d microcode a201016
The CPU ID and the Processor number may vary. To solve this problem you need to supply higher voltage to your CPU so that it is stable when running at peak frequencies. The easiest way to achieve this is to use the AMD curve optimiser which is accessible via your motherboard's bios. Access it and put a positive offset of 4 points, which will increase the voltage your CPU is getting at higher loads. It will limit overclocking potential due to higher heat dissipation requirements, but it will run stable. For more details check this forum post. When I did this for my 5950X, my processor stabilised and the frequency and voltage ranges were more similar to those observed under windows.
Screen-tearing (APU)
If you are using Xorg and are experiencing screen-tearing, enabling the "TearFree" option will fix the problem.
/etc/X11/xorg.conf.d/20-amdgpu.conf
Section "Device"
Identifier "AMD"
Driver "amdgpu"
Option "TearFree" "true"
EndSection
"TearFree" is not Vsync.Soft lock freezing
This bug is well known and is being discussed on bugzilla and launchpad. While the solution is not the same in all cases, this one helped some users. Add the output of this command echo rcu_nocbs=0-$(($(nproc)-1)) as a kernel parameter where the command nproc just prints your CPU's threads. For this option to be applied, you need a compiled kernel with option CONFIG_RCU_NOCB_CPU which linux is not.
A different cause for the freezes is the power saving management idicated by c-states. The maximum power saving state c6 can cause problems. Adding the kernel parameter processor.max_cstate=5 helped in some cases but other users reported that the option is not applied and the c6 state is still entered. For them, this package disable-c6-systemdAUR helped. Before using it, modeprobe msr needs to be run in order to activate that kernel module.
Some laptops with Ryzen CPUs such as the HP Envy x360 15-bq100na may experience CPU soft locks which result in a frozen system. These can be avoided with the kernel parameter "idle=nomwait" added.
Freeze on shutdown, reboot and suspend
This seems to be related to the C6 c-state, that does not seem to be well supported (if at all) in Linux.
To fix this issue, go into your BIOS settings for your motherboard and search for an option labeled something like this: "Power idle control". Change its value to "Typical current idle". Note that these names are dependent on what the motherboard manufacturer calls them, so they may be a little different in your particular case.
Other less ideal solutions include disabling c-states in the BIOS or adding processor.max_cstate=1 to your kernel command line arguments.