Wednesday, February 7, 2018

Nested virtualization on AMD ThreadRipper on Fedora 27

After much testing different kernel parameters and many emails between me and one of the kernel devs at Red Hat (I work there), I found a very simple solution to implementing nested virtualization on AMD ThreadRipper on Fedora 27.

Just run the 4.13 kernel for now. Everything works fine on 4.13. It turns out that 4.14 is broken for nested virt. That's all :/

Friday, January 12, 2018

Using a AMD Ryzen ThreadRipper with Fedora 27

Here's a collection of things that are useful to know if you are using a Ryzen ThreadRipper processor with Fedora.

  • SVM works fine, nSVM currently does not. However, virt-manager on Fedora 27 wants to use the EPYC processor type. This gives me odd warnings in dmesg, like

    smpboot: do_boot_cpu failed(-1) to wakeup CPU#1

    To get rid of these, I use Opteron_G2 as my processor type, which seems to work fine.
  • on the MSI x399 mainboard, if you want to read out your hardware sensors, you have to:

modprobe nct6775 force_id=0xd352

If you want to keep this after a reboot, do:

echo "options nct6775 force_id=0xd352" > /etc/modprobe.d/nct6775.conf
echo "nct6775" > /etc/modules-load.d/nct6775.conf

More to come :)