Arch Linux

manjack

Member

Registered: 2014-05-11

Posts: 9

Problem with intel_iommu

Hi

When i set intel_iommu=on in the /etc/default/grub.cfg, the screen freeze and hang after loading initramfs.

Does anyone know what problem is that? Thanks!

Buddlespit

Member

From: Chesapeake, Va.

Registered: 2014-02-07

Posts: 501

Re: Problem with intel_iommu

Some motherboards have an issue with the linux kernel and dma/memory mapping. If you change that to iommu=soft (intel_iommu=soft defaults to 'on') or turn off your iommu in the bios, you *SHOULDN'T* be plagued with iommu errors anymore.

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Hw-Probe

manjack

Member

Registered: 2014-05-11

Posts: 9

Re: Problem with intel_iommu

Some motherboards have an issue with the linux kernel and dma/memory mapping. If you change that to iommu=soft (intel_iommu=soft defaults to 'on') or turn off your iommu in the bios, you *SHOULDN'T* be plagued with iommu errors anymore.

Hi, thanks for your reply. Im trying to setup following the guide on this forum using kvm + vfio. What is the different if i set iommu=soft and iommu=on + turn off iommu in bios?

btw, my motherboard is asrock z87 extreme6.

Last edited by manjack (2014-05-19 03:57:06)

Buddlespit

Member

From: Chesapeake, Va.

Registered: 2014-02-07

Posts: 501

Re: Problem with intel_iommu

iommu=on + turn off in bios isn't going to do anything but turn off iommu, iommu=on will be a  wasted command. iommu=soft+iommu on in bios will turn on iommu and control it via software

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Hw-Probe

manjack

Member

Registered: 2014-05-11

Posts: 9

Re: Problem with intel_iommu

iommu=on + turn off in bios isn't going to do anything but turn off iommu, iommu=on will be a  wasted command. iommu=soft+iommu on in bios will turn on iommu and control it via software

Great, thank you for your answer

snovik

Member

Registered: 2012-05-06

Posts: 140

Re: Problem with intel_iommu

Sorry to revive this topic but after a veeeery long google I got here. I seem to have a video problem and for instance cannot play any youtube. The system gets really stuck after a couple of seconds/minutes. And sometimes even regular browsing blocks the system. But to the point...

Booting with iommu=soft seem to make the problem smaller. I can more or less play youtube without cpu going to 100%. More or less means that sometimes even with iommu=soft I am falling back into the old problem. I tried intel_soft as well but iommu seems to have the best results.

Would you have any additional suggestion as to what I could do to fully resolve it?

leonax

Member

Registered: 2014-10-20

Posts: 47

Re: Problem with intel_iommu

hi just to pipe in I have a gigabyte fxa-ud3 motherboard and I had to turn on iommu in bios and also to put iommu=pt in grub.cfg.  Otherwise if i did not put it on in bios I could not boot and if iommu=pt was not in grub I lost all usb drives.