How to compile a kernel for Ryzen processors

catweazel · Post by **catweazel** » Fri Oct 20, 2017 9:41 pm

Warning
Newcomers to linux are warned that this procedure may b0rk proprietary drivers and some third-party non-free software. Before proceeding to build your own kernel you should be proficient in searching google for solutions. If you b0rk your machine with this procedure then you're basically on your own because you've installed an unsupported kernel. You have been warned. If you have a spare hard disk, you are urged to perform a full backup before proceeding.

I use the NVIDIA proprietary driver and don't need to make any adjustments for it in the steps below. I cannot tell you if the same applies to the AMD proprietary driver.

Important
These instructions are for Linux Mint 18.2. They should work on other editions but if you're not using 18.2 then you'll need to make any adjustments without my help.

Introduction
For high-end machines it is highly recommended to install a low-latency kernel. A low-latency kernel is fractionally (imperceptibly) slower than a generic kernel, but it offers fantastic support for high-end multi-core CPUs and load sharing. The difference a low-latency kernel makes is very much noticeable when playing videos, doing video transcoding and performing other CPU intensive tasks. Additionally Mint 18.2 uses gcc version 5.4, which is capable of implementing CPU optimisations for Ryzen processors. Unfortunately these optimisations are not enabled by default in the kernel, so we must build our own kernel to activate them.

The reason for compiling a Ryzen-specific kernel is to deal with (for example)
certain bugs with the Ryzen processor, which, funnily enough, aren't found in the newer ThreadRipper series, and to obtain the benefits of CPU optimisations specific to the Ryzen CPU. The goal is increased stability.

Prerequisites

DO NOT overclock. Compiling while overclocking triggers one of the Ryzen bugs this
procedure is intended to defeat. If you find that all userland applications, keyboard,
mouse and desktop environment suddenly switch off but the computer remains on,
congratulations, you've triggered the bug.
Pack a lunch box and a flagon of ice water. One of the steps takes quite some time. The
download size is over 1.1GB so be aware of that if you're on a metered connection.
In case you do b0rk your machine, be aware that you can enter GrUB and select a
previous kernel. Usually you hold down the left shift key during boot if you don't
normally see the GrUB menu.
In case you do b0rk your machine and can't recover using a previous kernel, make sure
you have access to a spare device that can access the internet so you can search
Go-ogle[1] for solutions, but it shouldn't come to this.
If you've had to do anything to your system to get it running properly, make sure that
you have sufficient notes to recreate the steps. For example, you may have to reinstall
wifi drivers.

[1] ogle : verb : to stare at in a lecherous manner.

First, if one is using select proprietary or out-of-tree modules (ex. vitualbox, nvidia, fglrx, bcmwl, etc.) unless there is an extra package available for the version you are testing, you will need to uninstall the module first, in order to test the mainline kernel. If you do not uninstall these modules first, then the upstream kernel more than likely will not boot.

Source: Ubuntu Mainline builds wiki

The kernel will boot, but you may have to reinstall "out-of-tree modules", possibly including wifi drivers, from a terminal. Use Ctrl-Alt-F1 if X won't start and issue the appropriate commands to reinstall your video drivers. Alternatively you can boot the new kernel in recovery mode from the GrUB menu. Virtualbox should be ok because newer versions no longer rely on dkms.

Step 1: Install development tools
Start a terminal and stay in your home directory. If you prefer to build your kernel in /usr/src then make the necessary adjustments, otherwise just issue these commands: