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Configuring VMDirectPath I/O pass-through devices on an ESX host

Purpose

This article provides steps for configuring VMDirectPath I/O direct PCI device connections for virtual machines running on Intel Weybridge and Stoakley platforms.

Resolution

About VMDirectPath I/O pass-through devices

You can connect up to two passthrough (ESX 4.0) and up to four passthrough (ESX 4.1) devices to a virtual machine.When selecting the devices, keep in mind these restrictions:
  • Devices cannot be plugged in after a PCI Bridge.

  • Device must be behind a PCI Switch that supports ACS. For more information, see PCI Passthrough with PCIe devices behind a non-ACS switch in vSphere (1036811).

  • Devices cannot be plugged in after a non-ACS switch. For more information, see PCI Passthrough with PCIe devices behind a non-ACS switch in vSphere (1036811).

  • You cannot have two devices in two different contexts -- such as one used by VMkernel and one in pass-through -- using the same PCI slot. For example, the dual head NIC is dedicated to the VMkernel OR is available for pass-through. If you select one, the other is automatically selected as well. A dialog informs you why this occurred.

Configuring pass-through devices

To configure pass-through devices on an ESX host:
  1. Select an ESX host from the Inventory of VMware vSphere Client.

    Note: If you have a chipset with VT-d, when you click Advanced Settings in vSphere Client, you can select the devices that are dedicated to the VMDirectPath I/O.

  2. In the Configuration tab, click Advanced SettingsThe Pass-through Configuration page lists all available pass-through devices.

    Note
    A green icon indicates that a device is enabled and active. An orange icon indicates that the state of the device has changed and the host must be rebooted before the device can be used.

  3. Click Edit.
  4. Select the devices and click OK.
  5. When the devices are selected, they are marked with an orange icon. Reboot for the change to take effect. After rebooting, the devices are marked with a green icon and are enabled.

    Note: The configuration changes are saved in the /etc/vmware/esx.conf file. The parent PCI bridge, and if two devices are under the same PCI bridge, only one entry is recorded. 

    The PCI slot number where the device was connected is 00:0b:0. It is recorded as:

    /device/000:11.0/owner = "passthru"

    Note:
     11 is the decimal equivalent of the hexadecimal
     0b.
To configure a PCI device on a virtual machine:
  1. From the Inventory in vSphere Client, right-click the virtual machine and choose Edit Settings.
  2. Click the Hardware tab.
  3. Click Add.
  4. Choose the PCI Device.
  5. Click Next.

    Note: When the device is assigned, the virtual machine must have a memory reservation for the full configured memory size.
Based on VMware KB 1010789

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