A key piece of this offering of course is Red Hat Enterprise Linux which was expected to drop Xen in favor of KVM as the default virtualization engine.
The release notes of the just announced beta of RHEL 5.4 confirm this.
The KVM version included in RHEL 5.4 will support RHEL 3.x, 4.x and 5.x guest OSes along with Windows XP, Server 2003 and Server 2008.
All of them are supported in 32 and 64bits, and each OS will be able to run without installing any para-virtualized (PV) driver, despite these components will be available as part of the distribution.
No mention of Windows Server 2008 R2 and Windows 7 which will hit the RTM next week.
The Red Hat customers using Xen are not entirely left in the cold but their life will be much harder now:
Xen based virtualization is fully supported. However, Xen-based virtualization requires a different version of the kernel to function. The KVM hypervisor can only be used with the regular (non-Xen) kernel.
While Xen and KVM may be installed on the same system, the default networking configuration for these are different. Users are strongly recommended to use one hypervisor at a time.
This beta shouldn’t run more than a couple of months as Red Hat plans to release the new products on September 1, according to LeMagIT.