Red Hat Enterprise Linux 5

5.4 Release Notes

Release Notes for all architectures.

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This document details the Release Notes for Red Hat Enterprise Linux 5.4.
This document contains the Release Notes for the Red Hat Enterprise Linux 5.4 family of products including:
  • Red Hat Enterprise Linux 5 Advanced Platform for x86, AMD64/Intel® 64, Itanium Processor Family, System p and System z
  • Red Hat Enterprise Linux 5 Server for x86, AMD64/Intel® 64, Itanium Processor Family, System p and System z
  • Red Hat Enterprise Linux 5 Desktop for x86 and AMD64/Intel®
The Release Notes provide high level coverage of the improvements and additions that have been implemented in Red Hat Enterprise Linux 5.4. For detailed documentation on all changes to Red Hat Enterprise Linux for the 5.4 update, refer to the Technical Notes

1. Virtualization Updates

Red Hat Enterprise Linux 5.4 now includes full support for the Kernel-based Virtual Machine (KVM) hypervisor on x86_64 based architectures. KVM is integrated into the Linux kernel, providing a virtualization platform that takes advantage of the stability, features, and hardware support inherent in Red Hat Enterprise Linux. Virtualization using the KVM hypervisor is supported on wide variety of guest operating systems, including:
  • Red Hat Enterprise Linux 3
  • Red Hat Enterprise Linux 4
  • Red Hat Enterprise Linux 5
  • Windows XP
  • Windows Server 2003
  • Windows Server 2008


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 only install one hypervisor on a system.


Xen is the default hypervisor that is shipped with Red Hat Enterprise Linux. As such all configuration defaults are tailored for use with the Xen hypervisor. For details on configuring a system for KVM, please refer to the Virtualization Guide.
Virtualization using KVM allows both 32-bit and 64-bit versions of guest operating systems to be run without modification. Paravirtualized disk and network drivers have also been included in Red Hat Enterprise Linux 5.4 for enhanced I/O performance. All the libvirt based tools (i.e. virsh, virt-install and virt-manager) have also been updated with added support for KVM.
USB passthrough with the KVM hypervisor is considered to be a Technology Preview for the 5.4 release.
With resolution of various issues such as: save/restore, live migration and core dumps, Xen based 32 bit paravirtualized guests on x86_64 hosts are no longer classed as a Technology Preview, and are fully supported on Red Hat Enterprise Linux 5.4.
the etherboot package has been added in this update, providing the capability to boot guest virtual machines using the Preboot eXecution Environment (PXE). This process occurs before the OS is loaded and sometimes the OS has no knowledge that it was booted through PXE. Support for etherboot is limited to usage in the KVM context.
The qspice packages have been added to Red Hat Enterprise Linux 5.4 to support the spice protocol in qemu-kvm based virtual machines. qspice contains both client, server and web browser plugin components. However, only the qspice server in the qspice-libs package is fully supported. The qspice client (supplied by the qspice package) and qspice mozilla plugin (supplied by the qspice-mozilla package) are both included as Technology Previews. The qspice-libs package contains the server implementation that is used in conjunction with qemu-kvm and as such is fully supported. However, in Red Hat Enterprise Linux 5.4 there is no libvirt support for the spice protocol; the only supported use of spice in Red Hat Enterprise Linux 5.4 is through the use of the Red Hat Enterprise Virtualization product.


The virtio-win component is only available via the Red Hat Network, and is not included on the physical Supplementary CD for Red Hat Enterprise Linux 5.4. For more information, see the Red Hat Knowledgebase.