If you decided to move to AMD RYZEN or EPYC CPUs you probably experienced issues running PF_RING ZC, this is because application memory is provided to the network card (for directly moving packets with DMA) translating virtual addresses into physical addresses, and the IOMMU does not like it. In order to run PF_RING ZC on those processors you need to disable IOMMU support, you can do this following the steps below:
1. Set ‘IOMMU’ to ‘Disabled’ in your BIOS. Note: on Dell systems the ‘x2APIC Mode’ should be disabled in order to disable the ‘IOMMU’.
2. Disable amd_iommu in your GRUB boot parameters by appending ‘amd_iommu=off’ to GRUB_CMDLINE_LINUX /etc/default/grub and running ‘update-grub’ on Ubuntu or ‘grub2-mkconfig -o /boot/grub2/grub.cfg’ on CentOS.
Now you are ready to run ZC.
If you are running a UEFI-based system with CentOS/RHEL please note that the steps for configuring grub are a bit different. In that case you should run ‘grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg’ to update the boot laoder.