Installation guide

En able AMD IO MMU ext en sio n s
The AMD IOMMU extensions are required for PCI passthrough with Red Hat Enterprise Linux. The
extensions must be enabled in the BIOS. Some system manufacturers disable these extensions by
default.
AMD systems only require that the IOMMU is enabled in the BIOS. The system is ready for PCI
passthrough once the IOMMU is enabled.
Important
Xen and KVM require different kernel arguments to enable PCI passthrough. The previous
instructions are for KVM. For both AMD and Intel systems, PCI passthrough on Xen requires
the iommu=on parameter to the hypervisor command line. Modify the
/boot/grub/grub.conf file as follows to enable PCI passthrough:
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title Red Hat Enterprise Linux Server (2.6.18-192.el5)
root (hd0,0)
kernel /xen.gz-2.6.18-192.el5 iommu=on
module /vmlinuz-2.6.18-192.el5xen ro root=/dev/VolGroup00/LogVol00
module /initrd-2.6.18-190.el5xen.img
15.1. Adding a PCI device wit h virsh
These steps cover adding a PCI device to a fully virtualized guest under the Xen or KVM hypervisors
using hardware-assisted PCI passthrough. See Section 15.5, “ PCI passthrough for para-virtualized
Xen guests on Red Hat Enterprise Linux” for details on adding a PCI device to a para-virtualized Xen
guest.
Important
The VT-d or AMD IOMMU extensions must be enabled in BIOS.
This example uses a USB controller device with the PCI identifier code, pci_8086_3a6c, and a fully
virtualized guest named win2k3.
1. Id en t if y t h e d evice
Identify the PCI device designated for passthrough to the guest. The virsh nodedev-list
command lists all devices attached to the system. The --tree option is useful for identifying
devices attached to the PCI device (for example, disk controllers and USB controllers).
# virsh nodedev-list --tree
For a list of only PCI devices, run the following command:
# virsh nodedev-list | grep pci
⁠Chapt er 1 5. PCI passt hrough
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