Saturday, April 21, 2012

How to enable/disable Intel VT-d on XEN

Usually, you just need 'iommu=1' to enable VT-d. At the same time, most of VT-d features (DMA remapping, snoop control, queued invalidation and interrupt remapping) are enabled by default if they are available. You can use 'no-xxx' to disable a feature, for example, 'iommu=no-snoop' disable snoop control.
When RMRR address range is not in reserved memory (BIOS issue), can use 'iommu_inclusive_mapping=1' to work around it.
The grub configuration is like:
title Xen-Linux (2.6.18-xen)
        root (hd0,0)
        kernel /boot/xen.gz iommu=1
        module /boot/vmlinuz- root=LABEL=/
        module /boot/initrd-2.6.18-xen.img

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