4.34. xen

As of Red Hat Enterprise Linux 5.4, PCI devices connected to a single PCI-PCI bridge can no longer be assigned to different PV guests. If the old, unsafe behaviour is required, disable pci-dev-assign-strict-check in /etc/xen/xend-config.sxp. (BZ#508310)

Save operations should not be attempted on paused Xen domains. This will cause Xend to hang. (BZ#504910)

In live migrations of paravirtualized guests, time-dependent guest processes may function improperly if the corresponding hosts' (dom0) times are not synchronized. Use NTP to synchronize system times for all corresponding hosts before migration. (BZ#426861)

The Red Hat Enterprise Linux 3 kernel does not include SWIOTLB support. SWIOTLB support is required for Red Hat Enterprise Linux 3 guests to support more than 4GB of memory on AMD Opteron and Athlon-64 processors. Consequently, Red Hat Enterprise Linux 3 guests are limited to 4GB of memory on AMD processors. (BZ#504187)

When setting up interface bonding on dom0, the default network-bridge script may cause bonded network interfaces to alternately switch between unavailable and available. This occurrence is commonly known as flapping.

To prevent this, replace the standard network-script line in /etc/xen/xend-config.sxp with the following line:

			
(network-script network-bridge-bonding netdev=bond0)

			
(network-script network-bridge-bonding netdev=bond0)

Doing so will disable the netloop device, which prevents Address Resolution Protocol (ARP) monitoring from failing during the address transfer process. (BZ#429154)(BZ#429154)

The Hypervisor outputs messages regarding attempts by any guest to write to an MSR. Such messages contain the statement Domain attempted WRMSR. These messages can be safely ignored; furthermore, they are rate limited and should pose no performance risk. (BZ#477647)

Red Hat advises that you avoid removing a block device from a guest while the device is in use. Doing so causes Xend to lose domain information for the guest. (BZ#476164)

Installing Red Hat Enterprise Linux 3.9 on a fully virtualized guest may be extremely slow. In addition, booting up the guest after installation may result in hda: lost interrupt errors.

To avoid this bootup error, configure the guest to use the SMP kernel. (BZ#249521)