From 02b07de141b931e48a1dd2e6e0cd735bee6b3daa Mon Sep 17 00:00:00 2001 From: Pranav Dwivedi Date: Thu, 27 Aug 2026 10:02:46 +0530 Subject: [PATCH] OSDOCS-20054: Remove invalid amd_iommu=on kernel argument AMD IOMMU does not accept 'on' and is enabled by default when AMD-Vi is enabled in BIOS. Keep intel_iommu=on for Intel CPUs. --- .../virt-adding-kernel-arguments-enable-iommu.adoc | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/modules/virt-adding-kernel-arguments-enable-iommu.adoc b/modules/virt-adding-kernel-arguments-enable-iommu.adoc index a899213f477..753395d85aa 100644 --- a/modules/virt-adding-kernel-arguments-enable-iommu.adoc +++ b/modules/virt-adding-kernel-arguments-enable-iommu.adoc @@ -44,8 +44,15 @@ spec: # ... ---- ** `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. +** `metadata.name` specifies the ranking of this kernel argument (100) among the machine configs and its purpose. +** `spec.kernelArguments` specifies the kernel argument as `intel_iommu=on` for an Intel CPU. ++ +[NOTE] +==== +Do not specify `amd_iommu=on`. That value is not valid for the AMD IOMMU driver. The kernel ignores it and logs `AMD-Vi: Unknown option - 'on'`. +On AMD CPUs, IOMMU is enabled by default when AMD-Vi is enabled in the BIOS. You do not need an `amd_iommu=` kernel argument unless you require a supported option such as `off` or `force_enable`. +For PCI passthrough, you can optionally add `iommu=pt` to reduce DMA overhead. +==== . Create the new `MachineConfig` object: +