AMD Ryzen 7 3700X + Ryzen 9 3900X Offer Incredible Linux Performance But With A Big Caveat

To jump straight to the new stuff (Linux support and performance)... On the likes of Ubuntu 18.04 LTS, these new AMD Ryzen 7/9 series 7nm processors deliver incredible performance with the newest AMD X570 motherboards. The support on the likes of Ubuntu 18.04 LTS is great except for possible compatibility issues depending upon the particular motherboard/ASICs employed.

So what's the problem? On newer Linux distributions, there's a hard regression either within the kernel but more likely some cross-kernel/user-space interaction issue leaving newer Linux distributions unbootable.

While Ubuntu 18.04 LTS and older Linux distributions boot Zen 2, to date I have not been able to successfully boot the likes of Ubuntu 19.04, Manjaro Linux, and Fedora Workstation 31. On all newer Linux distributions I've tried on two different systems built around the Ryzen 7 3700X and Ryzen 9 3900X, each time early in the boot process as soon as trying to start systemd services, all systemd services fail to start.

I've confirmed with AMD they do have an open issue surrounding "5.0.9" (the stock kernel of Ubuntu 19.04) but as of writing hadn't shed any light into the issue. AMD has said their testing has been mostly focused on Ubuntu 18.04 given its LTS status. I've also confirmed the same behavior with some other Windows reviewers who occasionally dabble with Linux.

So unfortunately not being able to boot newer Linux distributions is a huge pain. I've spent days trying different BIOS versions/options, different kernel command line parameters, and other options to no avail. On some Linux distributions after roughly 20~30 minutes of waiting after all systemd services fail to start, sometimes there will be a kernel panic but that hadn't occurred on all systems at least not within that time-frame.

Complicating this issue further is that when trying Linux 5.0/5.1/5.2 kernels on Ubuntu 18.04 LTS, they all booted up fine! Hence it doesn't appear to simply be a kernel regression but either some kernel+systemd interaction issue happening just on AMD Ryzen 3000 series processors or some awkward thing happening with the X570 chipset. When asking AMD again on the day prior to launch, they were still investigating the issue and apparently unsure of the root cause at this time.

I've spent much time trying to figure out this issue and hoping some BIOS upgrade or settings adjustment or kernel command-line parameter exists to workaround this problem but so far have been unsuccessful in the time available. Otherwise basically all recent/new Linux distributions appear affected, at least those using systemd, appear impacted,

I'll update when receiving any further information or have discovered any other workaround, but for now at least be prepared to use Ubuntu 18.04 LTS or an older enterprise Linux distribution if concerned about Linux support/compatibility. This is unfortunate as going into this it looked like the AMD Zen 2 support for Linux was all lined-up and would be trouble-free, but hopefully this issue can be quickly resolved assuming it can be worked around with existing Linux distribution release ISOs.