9.18.8.2.2. Adding kernel arguments to enable the IOMMU driver

Procedure

1. Create a MachineConfig object that identifies the kernel argument. The following example shows a kernel argument for an Intel CPU.

   apiVersion: machineconfiguration.openshift.io/v1
   kind: MachineConfig
   metadata:
     labels:
       machineconfiguration.openshift.io/role: worker
     name: 100-worker-iommu
   spec:
     config:
       ignition:
         version: 3.2.0
     kernelArguments:
         - intel_iommu=on
   # ...

   • metadata.labels.machineconfiguration.openshift.io/role specifies that the new kernel argument is applied only to worker nodes.
   • metadata.name specifies the ranking of this kernel argument (100) among the machine configs and its purpose. If you have an AMD CPU, specify the kernel argument as amd_iommu=on.
   • spec.kernelArguments specifies the kernel argument as intel_iommu for an Intel CPU.

2. Create the new MachineConfig object:

   $ oc create -f 100-worker-kernel-arg-iommu.yaml

Verification

1. Verify that the new MachineConfig object was added by entering the following command and observing the output:

   $ oc get MachineConfig

   Example output:

   NAME                                       IGNITIONVERSION                    AGE
   00-master                                   3.5.0                             164m
   00-worker                                   3.5.0                             164m
   01-master-container-runtime                 3.5.0                             164m
   01-master-kubelet                           3.5.0                             164m
   01-worker-container-runtime                 3.5.0                             164m
   01-worker-kubelet                           3.5.0                             164m
   100-master-chrony-configuration             3.5.0                             169m
   100-master-set-core-user-password           3.5.0                             169m
   100-worker-chrony-configuration             3.5.0                             169m
   100-worker-iommu                            3.5.0                             14s

2. Verify that IOMMU is enabled at the operating system (OS) level by entering the following command:

   $ dmesg | grep -i iommu

   • If IOMMU is enabled, output is displayed as shown in the following example:

     Example output:

     Intel: [ 0.000000] DMAR: Intel(R) IOMMU Driver
     AMD: [ 0.000000] AMD-Vi: IOMMU Initialized