Installing KVM and QEMU No ACPI DMAR table found, IOMMU either disabled or not supported by this hardware platform

General system Applications
1

Hi there been using this guide ( https://sysguides.com/install-kvm-on-linux) to install. Everything went fine until point 6. Validate Host Virtualization Setup using

$ virt-host-validate qemu

QEMU: Checking for device assignment IOMMU support

WARN (No ACPI DMAR table found, IOMMU either disabled in BIOS or not supported by this hardware platform)

As I am using systemdboot I created a file /etc/dracut.conf.d/vfio.conf as I will use the VFIO driver for Windows images possibly with this content:

hostonly=" yes " hostonly_cmdline=" intel_iommu=on iommu=pt " force_drivers+=" vfio_pci vfio vfio_iommu_type1 "

then I ran
$ reinstall-kernels
$ reboot

Still the same issue:
WARN (No ACPI DMAR table found, IOMMU either disabled in BIOS or not supported by this hardware platform)

$ dmesg | grep DMAR result DMAR: IOMMU enabled
$ lscpu | grep Virtualization
Virtualization: VT-x

I had no issues when using Oracle VM VirtualBox or VMWare but I am trying to get away from proprietary software.

Any guidance will be appreciated

2

Perhaps your issue:

Your Intel processor only supports the VT-x (vmx) feature and not VT-d.

To enable VT-d…

3

@dirkduplooy

https://discovery.endeavouros.com/applications/how-to-install-virt-manager-complete-edition/2021/09/

4

VT-d, which provides IOMMU services, is a very important feature for realizing the security promises of Qubes OS.

As indicated above ran $ dmesg | grep DMAR and the result
DMAR: IOMMU enabled
So VT-d is enabled

5

Hi @ricklinux did use that guide before using the first mentioned and still got the same message when validating qemu
QEMU: Checking for device assignment IOMMU support : WARN (No ACPI DMAR table found, IOMMU either disabled in BIOS or not supported by this hardware platform)

6

I reallly don’t know what the issue is. I’m not using virt-manager currently although i have in the past. I am using vmware workstation pro. I’ve also never used pci passthrough on kvm.

Edit: Also never ran Windows on vm.

7

@ricklinux Thanks, I will install VMWare Workstation Pro

8

If you dump that question into an AI engine you will get an answer something like this.

The warning message you received from QEMU indicates that the system could not find an ACPI DMAR table, which is necessary for IOMMU (Input-Output Memory Management Unit) support. This could be due to the IOMMU being disabled in the BIOS/UEFI settings or the hardware platform not supporting IOMMU.

Your system’s motherboard needs to support, if it does you might need to enable it in your uefi settings.

Check the status of IOMMU, the output should return that iommu is enabled or supported.
dmesg | grep -e DMAR -e IOMMU

Check the status of DMARC, you should see output of DMAR table being present.
dmesg | grep DMAR

This last one on my Proxmox system doesn’t have it enabled but iommu works so I don’t think this is necessary

You need to enable it in your bootloader.
intel_iommu=on or amd_iommu=on
Then reboot.

If you hardware doesn’t support IOMMU I doubt it will work on vmware unless vmware implented those features differently.

9

Thanks it does support it, actually gave the output in the first post. No harm done, I researched thoroughly before I asked the question here. Both VMWare and VirtualBox work without issues. Thanks for replying

1 Like
10

@Cphusion

11

Just thought I’d drop my thoughts. I’ve never setup IOMMU on Arch Linux only on my Proxmox system where I run a vm that runs my Mediaserver where I use an Nvidia gpu for transcoding if needed.

1 Like
12

This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.