Installation guide

Release Notes

• Fully virtualized Red Hat Enterprise Linux 5 guests encountered suboptimal performance when

using emulated disk and network devices. In this update, the kmod-xenpv package has been

included to simplify the use of paravirtualized disks and networks in fully virtualized guests.

Using these drivers in fully virtualized guests can significantly improve the performance and

functionality of fully virtualized guests. Bug fixes made for netfront and block front drivers are

immediately realized and synchronized with the kernel package.

• Guests now have the ability to utilize 2MB backing page memory tables, which can improve system

performance.

6.2. Resolved Issues

6.2.1. All Architectures

• Shutting down a paravirtualized guest may have caused the dom0 to stop responding for a

period of time. Delays of several seconds were experienced on guests with large amounts of

memory (ie 12GB and above.) In this update, the virtualized kernel allows the shutdown of a large

paravirtualized guest to be pre-emptible, which resolves this issue.

• crash was unable to read the relocation address of the hypervisor from a vmcore file.

Consequently, opening a Virtualized kernel vmcore file with crash would fail, resulting in the error:

crash: cannot resolve "idle_pg_table_4"

In this update, the hypervisor now saves the address correctly, which resolves this issue.

• Previously, paravirtualized guests could only have a maximum of 16 disk devices. In this update,

this limit has been increased to a maximum of 256 disk devices.

• Memory reserved for the kdump kernel was incorrect, resulting in unusable crash dumps. In this

update, the memory reservation is now correct, allowing proper crash dumps to be generated.

• Attaching a disk with a specific name (ie. /dev/xvdaa, /dev/xvdab, /dev/xvdbc etc.) to a

paravirtualized guest resulted in a corrupted /dev device inside the guest. This update resolves the

issue so that attaching disks with these names to a paravirtualized guest creates the proper /dev

device inside the guest.

• Previously, the number of loopback devices was limited to 4. Consequently, this limited the ability to

create bridges on systems with more than 4 network interfaces. In this update, the netloop driver

now creates additional loopback devices as required.

• A race condition could occur when creating and destroying virtual network devices. In some

circumstances — especially high load situations — this would cause the virtual device to not

respond. In this update, the state of the virtual device is checked to prevent the race condition from

occurring.

• a memory leak in virt-manager would be encountered if the application was left running.

Consequently, the application would constantly consume more resources, which may have led to

memory starvation. In this update, the leak has been fixed, which resolves this issue.