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I'm setting up a vm box and I've enabled IOMMU.

Works great, except I get PTE Read access is not set errors flooding my dmesg.

In particular it is for one device, a USB 1.1 controller, that just doesn't want to play ball. If I detach the device (using virsh) the errors stop.

So my question is, is there a way to enable IOMMU on a address basis (or disable), or how do I detach a device from the host automatically?

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You can pass the device off to pci-back with kernel arguments; some messages may still leak into dmesg, but the device will get yanked pretty early.

If you have pciback as part of your kernel, it's just pciback.hide=(03:00.0) for example.

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