What follows are Red Hat's release notes, unchanged from their original.
These notes are here provided as a reference for PU_IAS Linux 5 which is built
from Red Hat provided open source rpms. In no way, form or fashion does the
presence of these notes imply any kind of support, endorsment or any other
aknowledgement by Red Hat of PU_IAS Linux 5. PU_IAS Linux 5 is not a Red Hat
supported product and any questions about it should be directed at
http://www.elders.princeton.edu/

================================================================================

---------------------------------------------------------------------------

Introduction

The following topics are covered in this document:

o Installation-Related Notes

o Technology Previews

o Known Issues

o General Information

o Driver Update Program

o Internationalization

o Kernel Notes

Some updates on Red Hat Enterprise Linux 5 may not appear in this version
of the Release Notes. An updated version of the Release Notes may also be
available at the following URL:

[2]http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/index.html

Installation-Related Notes

The following section includes information specific to the installation of
Red Hat Enterprise Linux and the Anaconda installation program.

Note

In order to upgrade an already-installed Red Hat Enterprise Linux, you
must use Red Hat Network to update those packages that have changed.

You may use Anaconda to perform a fresh installation of Red Hat Enterprise
Linux 5 or to perform an upgrade from the latest updated version of Red
Hat Enterprise Linux 4 to Red Hat Enterprise Linux 5.

If you are copying the contents of the Red Hat Enterprise Linux 5 CD-ROMs
(in preparation for a network-based installation, for example) be sure to
copy the CD-ROMs for the operating system only. Do not copy the
Supplementary CD-ROM, or any of the layered product CD-ROMs, as this will
overwrite files necessary for Anaconda's proper operation. These CD-ROMs
must be installed after Red Hat Enterprise Linux has been installed.

ISO Contents and Registration

The organization of software component packages into product-specific
variants has changed from previous versions of Red Hat Enterprise Linux.
The total number of different variants and ISO images has been reduced to
two:

o Red Hat Enterprise Linux 5 Server

o Red Hat Enterprise Linux 5 Client

The ISO images contain software packages for a number of optional
repositories that provide additional functionality over the core
distribution, such as Virtualization, Clustering or Cluster Storage. For
more information about the Server variants, Client variants and available
options, please refer to [3]http://www.redhat.com/rhel/.

With optional content in the same tree or ISO image, it is important to
avoid a mismatch between the components offered for installation and those
covered by the subscription. Such a mismatch could result in an increased
exposure to bug and vulnerability risks.

In order to ensure that the components offered are in sync with the
subscription, Red Hat Enterprise Linux 5 requires entering an Installation
Number that will be used to configure the installer to offer the right
package set. This Installation Number is included in your subscription.

If you skip entering the Installation Number, this will result in a core
Server or Desktop installation. Additional functionality can then be added
manually at a later time. For more information about Installation Numbers,
please refer to [4]http://www.redhat.com/apps/support/in.html.

The Installation Number used during the installation process will be saved
in /etc/sysconfig/rhn/install-num. When registering with Red Hat Network,
this file will be referenced by rhn_register to automatically determine
which appropriate child channels the system should be subscribed to.

New RPM GPG Signing Keys

A new release signing key is used to sign Red Hat Enterprise Linux 5
packages. When updating a system for the first time, you will be prompted
to allow this key to be installed.

Signing keys are distributed in the following files:

o /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release -- contains the public key
for the new release signing key

o /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-auxiliary -- contains the public
key for an auxiliary release signing key, currently not in use

o /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-former -- contains the public key
for the previous release signing key, used for past Red Hat Enterprise
Linux releases

Subversion

In Red Hat Enterprise Linux 5, the Subversion version control system is
linked against Berkeley DB 4.3. If you are upgrading from Red Hat
Enterprise Linux 4 and any Subversion repositories which use the Berkeley
DB backend "BDB" (rather than the pure file system-based "FSFS" backend)
have been created on the system, special care must be taken to ensure the
repositories can be accessible after the upgrade. The following process
must be performed on the Red Hat Enterprise Linux 4 system, prior to
upgrading to Red Hat Enterprise Linux 5:

1. Shut down any running processes and ensure that no processes can
access the repository (for example, httpd, svnserve or any local users
with direct access).

2. Create a backup of the repository using the following command:

svnadmin dump /path/to/repository | gzip > repository-backup.gz

3. Run the svnadmin recover command on the repository:

svnadmin recover /path/to/repository

4. Delete any unused log files in the repository:

svnadmin list-unused-dblogs /path/to/repository | xargs rm -vf

5. Delete any remaining shared-memory files in the repository:

rm -f /path/to/repository/db/__db.0*

Other Installation Notes

o If IDE/PATA (Parallel ATA) devices are configured in "100% Native"
mode, some BIOSes may prevent the Red Hat Enterprise Linux 5
installation process from completing successfully. To prevent this
from occurring, configure the IDE/PATA mode as "Legacy" in the BIOS.

o The IBM System z does not provide a traditional Unix-style physical
console. As such, Red Hat Enterprise Linux 5 for the IBM System z does
not support the firstboot functionality during initial program load.

To properly initialize setup for Red Hat Enterprise Linux 5 on the IBM
System z, run the following commands after installation:

o /usr/bin/setup -- provided by the setuptool package

o /usr/bin/rhn_register -- provided by the rhn-setup package

o When booting Anaconda with PXE using the parameter ksdevice=bootif,
you will still be prompted for the ethernet interface to use during
installation. If only one ethernet device is plugged in, use the
parameter ksdevice=link instead. Alternatively, you can also specify
the interface manually.

Technology Previews

Technology Preview features are currently not supported under Red Hat
Enterprise Linux 5 subscription services, may not be functionally
complete, and are generally not suitable for production use. However,
these features are included as a customer convenience and to provide the
feature with wider exposure.

Customers may find these features useful in a non-production environment.
Customers are also free to provide feedback and functionality suggestions
for a technology preview feature before it becomes fully supported.
Erratas will be provided for high-severity security issues.

During the development of a technology preview feature, additional
components may become available to the public for testing. It is the
intention of Red Hat to fully support technology preview features in a
future release.

Stateless Linux

Included in this release of Red Hat Enterprise Linux 5 are
enabling infrastructure pieces for Stateless Linux. Stateless
Linux is a new way of thinking about how a system is to be run and
managed, designed to simplify provisioning and management of large
numbers of systems by making them easily replaceable. This is
accomplished primarily by establishing prepared system images
which get replicated and managed across a large number of
stateless systems, running the operating system in a read-only
manner (please refer to /etc/sysconfig/readonly-root for more
details).

In its current state of development, the Stateless features are
subsets of the intended goals. As such, the capability is being
labeled as a technology preview.

The following is a list of the initial capabilities included in
Red Hat Enterprise Linux 5:

o running a stateless image over NFS

o running a stateless image via loopback over NFS

o running on iSCSI

It is highly recommended that those interested in testing
stateless code read the HOWTO at
[5]http://fedoraproject.org/wiki/StatelessLinuxHOWTO and join
[6]stateless-list@redhat.com.

GFS2

GFS2 is an evolutionary advancement based on the GFS file system.
While fully functional, GFS2 is not yet considered
production-ready. GFS2 is targeted to become fully supported in a
subsequent Red Hat Enterprise Linux 5 update. There is also an
in-place conversion utility, gfs2_convert, which can update the
metadata of the older GFS file system format, converting it to a
GFS2 file system.

FS-Cache

FS-Cache is a local caching facility for remote file systems that
allows users to cache NFS data on a locally mounted disk. To set
up the FS-Cache facility, install the cachefilesd RPM and refer to
the instructions in /usr/share/doc/cachefilesd-<version>/README.

Replace <version> with the corresponding version of the
cachefilesd package installed.

Compiz

Compiz is an OpenGL-based compositing window manager. In addition
to regular window management, compiz also acts as a compositing
manager, coordinating and synchronizing the overall desktop
redrawing to provide a smoother desktop experience with less
flicker.

Compiz uses 3D hardware acceleration to render effects such as
live thumbnail windows, window drop shadows, animated window
minimizing and transitions between virtual desktops.

Due to limitations in the current rendering architecture, compiz
cannot work correctly with direct rendering OpenGL applications or
applications using the Xv extension. Such applications will
exhibit harmless rendering artifacts; because of this, compiz is
currently a technology preview.

Enhancement for Ext3

In Red Hat Enterprise Linux 5, the EXT3 file system capacity has
been extended beyond 8TB to a maximum of 16TB. This capability is
being included as a technology preview, and is targeted for full
support in a future release of Red Hat Enterprise Linux 5.

AIGLX

AIGLX is a technology preview feature of the otherwise fully
supported X server. It aims to enable GL-accelerated effects on a
standard desktop. The project consists of the following:

o a lightly modified X server

o an updated Mesa package that adds new protocol support

By installing these components, you can have GL-accelerated
effects on your desktop with very few changes, as well as the
ability to enable and disable them at will without replacing your
X server. AIGLX also enables remote GLX applications to take
advantage of hardware GLX acceleration.

Frysk GUI

The goal of the frysk project is to create an intelligent,
distributed, always-on system monitoring and debugging tool that
allows developers and system administrators to:

o monitor running processes and threads (including creation and
destruction events)

o monitor the use of locking primitives

o expose deadlocks

o gather data

o debug any given process by choosing it from a list or
allowing frysk to open a source code (or other) window on a
process that is crashing or misbehaving

In Red Hat Enterprise Linux 5 the frysk graphical user interface
is a technology preview, whereas the frysk command line interface
is fully supported.

Systemtap

Systemtap provides free software (GPL) infrastructure to simplify
the gathering of information about the running Linux system. This
assists diagnosis of a performance or functional problem. With the
help of systemtap, developers no longer need to go through the
tedious and disruptive instrument, recompile, install, and reboot
sequence that may be otherwise required to collect data.

Dogtail

Dogtail is a GUI test tool and automation framework written in
Python that uses Accessibility technologies to communicate with
desktop applications.

Support for Indic Languages and Sinhalese

Red Hat Enterprise Linux 5 also features support for the following
languages as technology preview:

o Assamese

o Kannada

o Sinhalese

o Telugu

For more information about how to install and enable support for
these languages, refer to the Internationalization section of this
document.

Installing to dm-multipath Devices

Anaconda now has the capability to detect, create, and install to
dm-multipath devices. To enable this feature, add the parameter
mpath to the kernel boot line.

Note that the parameter mpath may cause a boot failure if a
device's major:minor number changes. This issue will be addressed
in a future update of Red Hat Enterprise Linux 5.

Installation / Boot for iSCSI software initiator (open-iscsi)

Anaconda now provides the ability to install to an iSCSI device.
Booting and installing is fully supported with the QLogic qla4xxx
hardware initiator. However, the capability to install to an iSCSI
device for the open-iscsi software initiator is currently
considered a Technology Preview, due to the following issues:

o Text mode installation does not complete. You must do a
graphical install, or an automated kickstart install.

o Media-based installations do not complete. You must do a
network-based install.

o Depending on the timing of events, Anaconda may be unable to
detect all the iSCSI targets or LUNs. When this occurs, use
the installer shell to configure the storage through iSCSI
commands.

o The iscsid daemon may not properly start. Such an occurence
will prevent the system from handling all iSCSI errors, such
as network problems, SCSI/iSCSI timeouts, and target errors.
To confirm that the iscsid daemon is running, run the command
iscsiadm -m session -i and check that the line, Internal
iscsid Session State: reports a value (it can be any value).

o On certain iSCSI target implementations, the system may hang
during shutdown.

o On certain iSCSI target implementations, the system may hang
during reboot. To avoid this, shutdown the system and boot it
up again (instead of rebooting directly from a session).

o Booting from iSCSI devices on the IBM System p does not work
reliably. While installation on an iSCSI device may appear to
succeed, the resulting installation will not boot properly.

o On the first boot after install, you may receive SELinux
errors such as the following:

kernel: audit(1169664832.270:4): avc: denied { read
} for pid=1964 comm="iscsid"

To work around this, boot the system with the kernel
parameter enforcing=0. Once the system has properly booted,
use the command setenforce 1 to restore enforcing mode.

These limitations will be addressed in a future Red Hat Enterprise
Linux 5 update.

Known Issues

o Host bus adapters that use the MegaRAID driver must be set to operate
in "Mass Storage" emulation mode, not in "I2O" emulation mode. To do
this, perform the following steps:

1. Enter the MegaRAID BIOS Set Up Utility.

2. Enter the Adapter settings menu.

3. Under Other Adapter Options, select Emulation and set it to Mass
Storage.

If the adapter is incorrectly set to "I2O" emulation, the system will
attempt to load the i2o driver. This will fail, and prevent the proper
driver from being loaded.

Previous Red Hat Enterprise Linux releases generally do not attempt to
load the I2O driver before the MegaRAID driver. Regardless of this,
the hardware should always be set to "Mass Storage" emulation mode
when used with Linux.

o When you install a fully virtualized guest configured with vcpus=2,
the fully virtualized guest may take an unreasonably long time to boot
up.

To work around this, destroy the slow-booting guest using the command
xm destroy <guest id> and then use xm create <guest id> to start the
same guest afterwards.

o Red Hat Enterprise Linux 5 includes openmpi-1.1.1-4.el5 (from the OFED
1.1 distribution), which has been discovered to eventually quit
working entirely. This happens after the openmpi stack works as
expected for a varying amount of time.

For updated versions of openmpi, please check
[7]http://people.redhat.com/dledford/Infiniband/openmpi

o Installing Windows Server 2003 as a guest on a fully virtualized Red
Hat Enterprise Linux 5 system ends unexpectedly after completing the
first stage of installation. When this happens, the graphical console
window closes, and the guest disappears from the Virtual Machine
Manager's list of machines, resulting in a Broken pipe error.

This issue will be resolved in an upcoming Red Hat Enterprise Linux 5
update. To work around this, use the following command at the
terminal:

xm create /etc/xen/<name of guest machine>

Afterwards, open the virtual machine.

o When attempting to create a fully virtualized Windows Server 2003 from
a CD / DVD, the second stage of the guest install will not continue
upon reboot.

To work around this, edit /etc/xen/<name of guest machine> by properly
appending an entry for the CD / DVD device.

If an installation to a simple file is used as a virtual device, the
disk line of /etc/xen/<name of guest machine> will read like the
following:

disk = [ 'file:/PATH-OF-SIMPLE-FILE,hda,w']

A DVD-ROM device located on the host as /dev/dvd can be made available
to stage 2 of the installation as hdc by appending an entry like
'phy:/dev/dvd,hdc:cdrom,r'. As such, the disk line should now read as
follows:

disk = [ 'file:/opt/win2003-sp1-20061107,hda,w', 'phy:/dev/dvd,hdc:cdrom,r']

The precise device path to use may vary depending on your hardware.

o rmmod xennet causes domU to crash; this is caused by a grant table
issue in the Virtualization feature. Due to the current inability of
the Virtualization feature to asynchronously release grant table
operations, it is unsafe to unload the xennet module in guests. In
such situations, grant tables are used to perform backend-frontend
communication, and there is no guarantee that the backend will release
the references, leading to an inevitable memory leak.

This issue will be resolved in the next minor release of Red Hat
Enterprise Linux 5. At present, users are advised not to unload the
xennet module in guests.

o Running ethtool eth0 outputs incomplete information about the ethernet
card settings. This only occurs in systems running a virtualized
kernel, since the Virtualization feature uses a networking setup where
the physical ethernet device is identified as peth0. As such, the
correct command for retrieving information about the physical ethernet
device is ethtool peth0.

o Installing the Virtualization feature may cause a time went backwards
warning on HP systems with model numbers xw9300 and xw9400.

To work around this issue for xw9400 machines, configure the BIOS
settings to enable the HPET timer. Note that this option is not
available on xw9300 machines.

HP will notify xw9300 and xw9400 users when a new BIOS image is
available.

o When using Red Hat Enterprise Linux 5 on a machine with an nVidia
CK804 chipset installed, you may receive kernel messages similar to
the following:

kernel: assign_interrupt_mode Found MSI capability
kernel: pcie_portdrv_probe->Dev[005d:10de] has invalid IRQ. Check vendor BIOS

These messages indicate that certain PCI-E ports are not requesting
IRQs. Further, these messages do not, in any way, affect the operation
of the machine.

o Some Cisco Aironet Wireless devices prevent NetworkManager from
storing connection details for wireless networks that do not broadcast
an SSID. This is caused by a Cisco Aironet Wireless device firmware
limitation.

o Laptops that have the Cisco Aironet MPI-350 wireless card equipped may
hang trying to get a DHCP address during any network-based
installation using the wired ethernet port.

To work around this, use local media for your installation.
Alternatively, you can disable the wireless card in the laptop BIOS
prior to installation (you can re-enable the wireless card after
completing the installation).

o Currently, system-config-kickstart does not support package selection
and deselection. When using system-config-kickstart, the Package
Selection option indicates that it is disabled. This is because
system-config-kickstart uses yum to gather group information, but is
unable to configure yum to connect to Red Hat Network.

This issue is currently being investigated for resolution by the next
minor release of Red Hat Enterprise Linux 5. At present, you need to
update package sections in your kickstart files manually. When using
system-config-kickstart to open a kickstart file, it will preserve all
package information in it and write it back out when you save.

o Systems with SATA controllers may pause during the boot process,
displaying the following error message:

ata2: port is slow to respond, please be patient

Afterwards, the following error message appears:

ata2: reset failed, giving up

Note that after the second error message, the system will continue the
normal boot process. Other than the delay, there is no impact to the
system; as long as the SATA drives are physically present they will
still be detected properly.

o 4-socket AMD Sun Blade X8400 Server Module systems that do not have
memory configured in node 0 will panic during boot. Systems should be
configured with memory in node 0 to prevent the kernel panic.

o Installing to LVM mirror devices through Anaconda is currently not
supported. This capability will be added in a future update of Red Hat
Enterprise Linux 5.

o When installing Red Hat Enterprise Linux 5 from a directory on an NFS
server containing Red Hat Enterprise Linux ISO images, Anaconda may
display the following error message:

Unable to read package metadata. This may be due to a missing repodata directory.
Please ensure that your install tree has been correctly generated. Cannot
open/read repomd.xml file for repository:

This problem occurs if the directory holding the ISO images also
contains a partially unpacked installation tree (for example, the
/images directory from the first ISO). The presence of such
directories results in the error stated above.

To prevent this error, unpack trees only to directories other than the
one containing the installation ISO images.

o Boot-time logging to /var/log/boot.log is not available in this
release of Red Hat Enterprise Linux 5. An equivalent functionality
will be added in a future update of Red Hat Enterprise Linux 5.

o Neither kexec nor kdump are able to dump onto disks attached to an
accraid controller.

To work around this issue, use scp for network dumping. Alternatively,
you can also dump onto a disk through a different controller.

o Running tvtime and xawtv with the bttv kernel module causes the system
to freeze. This issue will be addressed in an upcoming minor release
of Red Hat Enterprise Linux 5.

To work around this, add the parameter mem=3000m to the kernel boot
line.

o The Supplementary CD of this release contains the Mozilla plugins
flash-plugin and acroread-plugin. Both of these plug-ins are 32-bit,
and as such it is recommended that they not be installed with the
64-bit Firefox browser.

o Installing a fully virtualized guest using split installation media --
specifically, multiple CD-ROMs -- may fail when required to switch
between installation CDs. During the guest OS installation process,
users may be prevented from mounting or ejecting installation CDs,
which prevents the installation from completing.

As such, it is recommended that you use the QEMU monitor console to
switch CD-ROM images during the guest OS installation process. The
procedure is as follows:

1. Open a graphical VNC console to the guest OS.

2. Unmount the CD-ROM device in the guest OS.

3. Switch to the QEMU monitor console by pressing Ctrl-Alt-2.

4. Run the command eject hdc.

5. Run the command change hdc <path to the CD-ROM in host system>.

6. Switch back to the guest OS console by pressing Ctrl-Alt-1.

7. Mount the CD-ROM device in the guest OS.

Note that when using a regular VNC client the host X server may
encounter some difficulty interpreting the Ctrl-Alt-2 and Ctrl-Alt-1
command. To work around this in virt-manager, use sticky keys.
Pressing Ctrl three times makes it "sticky" until the next
non-modifier is pressed. As such, to send Ctrl-Alt-1, press Ctrl twice
before pressing Ctrl-Alt-1.

o Some machines that use NVIDIA graphics cards may display corrupted
graphics or fonts when using the graphical installer or during a
graphical login. To work around this, switch to a virtual console and
back to the original X host.

o The Red Hat Enterprise Linux 5 Driver Update Model creates modified
initrd images whenever a kmod package that includes a
bootpath-modifying driver is installed. In time, the number of backup
initrd images may soon fill the /boot partition, particularly if the
system undergoes a sizeable number of driver updates.

As such, it is recommended that you monitor the free space on the
/boot partition if you regularly perform driver updates. You can free
up more space in /boot by removing older initrd images; these files
end in .img0, .img1, .img2, and so on.

o The Red Hat Enterprise Linux virtualization kernel may not work
correctly with more than 64GB of memory. To boot the virtualization
kernel on machines that have more than 64GB of physical memory
installed, you may need to add dom0_mem=4G mem=64G to the kernel
command-line. For example:

title Red Hat Enterprise Linux Server (2.6.18-4.el5xen)
root (hd0,0)
kernel /xen.gz-2.6.18-4.el5 dom0_mem=4G mem=64G
module /vmlinuz-2.6.18-4.el5xen ro root=LABEL=/
module /initrd-2.6.18-4.el5xen.img

o Autorun on removable media is currently disabled. To install packages
from the Red Hat Enterprise Linux Supplementary CD, launch the CD
installer manually using the following command:

system-cdinstall-helper /media/path-to-mounted-drive

o When upgrading from Red Hat Enterprise Linux 4 to Red Hat Enterprise
Linux 5, the Deployment Guide is not automatically installed. You need
to use pirut to manually install it after completing the upgrade.

o An autofs bug prevents multi-mounts from working properly.

During an expiry, if the last multi-mount component to be checked does
not have a mount associated with it while other components are busy,
autofs erroneously determines the multi-mount to be expirable. This
causes the multi-mount to be partially expired, resulting in the
multi-mount becoming unresponsive to further mount requests and expire
runs.

To permanently resolve this problem, update autofs using the command
yum update autofs.

o The system may not successfully reboot into a kexec/kdump kernel if X
is running and using a driver other than vesa. This problem only
exists with ATI Rage XL graphics chipsets.

If X is running on a system equipped with ATI Rage XL, ensure that it
is using the vesa driver in order to successfully reboot into a
kexec/kdump kernel.

o Creating a fully virtualized guest using a boot.iso on an NFS share
mounted as read-write will not complete correctly. To work around this
problem, mount the NFS share as read-only.

If you are unable to mount the NFS share as read-only, copy the
boot.iso to the local /var/lib/xen/images/ directory.

General Information

This section contains general information not specific to any other
section of this document.

Red Hat Enterprise Linux Deployment Guide

This release of Red Hat Enterprise Linux includes a fairly
comprehensive Deployment Guide. To access it, go to System (on the
top panel) => Documentation => Red Hat Enterprise Linux Deployment
Guide.

It is the intention of Red Hat to provide fully localized versions
of the Deployment Guide for all supported languages. If you have
installed a localized version of the Deployment Guide, it is
recommended that you update it when a new version becomes
available through Red Hat Network.

Virtualization

Red Hat Enterprise Linux 5 features Xen-based virtualization
capabilities for i686 and x86-64, as well as the software
infrastructure needed to manage a virtualized environment.

The implementation of Virtualization in Red Hat Enterprise Linux 5
is based on the hypervisor, which facilitates extremely low
overhead virtualization through paravirtualization. With Intel
Virtualization Technology or AMD AMD-V capable processors,
virtualization in Red Hat Enterprise Linux 5 also allows operating
systems to run unmodified in fully virtualized mode.

Virtualization on Red Hat Enterprise Linux 5 also features the
following:

o Libvirt, a library that provides a consistent, portable API
for managing virtual machines.

o Virtual Machine Manager, a graphical utility for monitoring
and managing virtual machines.

o Virtual machine support in the installer, including the
ability to kickstart virtual machines.

Red Hat Network also supports virtual machines.

At present, the Virtualization feature has the following
limitations:

o When Virtualization is enabled, neither suspend to RAM nor
suspend to disk are supported, and CPU frequency scaling
cannot be performed.

o Hardware-virtualized guests cannot have more than 4GB of
virtual memory.

o Fully virtualized guests cannot be saved, restored or
migrated.

o The xm create command does not have a graphical equivalent in
Virtual Machine Manager.

o Virtualization only supports the bridged networking
component. All corresponding tools used by guests
automatically choose this as the default.

o The default Red Hat SELinux policy for Virtualization only
allows configuration files to be written to /etc/xen, log
files to be written to /var/log/xen/, and disk files
(including core dumps) to be written to /var/lib/xen. These
defaults can be changed using the semanage tool.

o The hypervisor included in this release of Virtualization is
not NUMA-aware; as such, its performance on NUMA machines may
be sub-optimal. This will be addressed in a future update of
Red Hat Enterprise Linux 5.

To work around this, enable memory node interleaving in the
NUMA machine's BIOS. This ensures a more consistent
performance.

o Paravirtualized domains currently do not support keymaps
other than en-US. As such, other keyboards may not be able to
type certain keystrokes. This will be addressed in a future
update of Red Hat Enterprise Linux 5.

o The virtualized kernel cannot use the kdump function.

o qcow and vmdk images are not supported. When manually
configuring guests, images backed by a physical or logical
device should use the phy: type. For file-backed images, set
the image type to tap:aio: for paravirtualized guests and
file: for fully virtualized guests.

o Paravirtualized domains can only auto-detect relative mouse
movement, and pointer movement is rather erratic. This will
be addressed in a future update of Red Hat Enterprise Linux
5.

o In order to have a working console for a paravirtualized
guest, you need to specify console=xvc0 in the kernel command
line.

o When guest operating systems are configured to use sparse
files, dom0 can run out of disk space. Such occurences
prevent guest disk writes from completing, and can cause data
loss in guests. Further, guests that use sparse files do not
synchronize I/O safely.

As such, it is recommended that you use non-sparse files
instead. To configure guests to use non-sparse files, use the
option --nonsparse when conducting a virt-install.

Web Server Packaging Changes

Red Hat Enterprise Linux 5 now includes version 2.2 of the Apache
HTTP Server. This release brings a number of improvements over the
2.0 series, including:

o improved caching modules (mod_cache, mod_disk_cache,
mod_mem_cache)

o a new structure for authentication and authorization support,
replacing the authentication modules provided in previous
versions

o support for proxy load balancing (mod_proxy_balancer)

o support for handling large files (namely, greater than 2GB)
on 32-bit platforms

The following changes have been made to the default httpd
configuration:

o The mod_cern_meta and mod_asis modules are no longer loaded
by default.

o The mod_ext_filter module is now loaded by default.

If you are upgrading from a previous release of Red Hat Enterprise
Linux, the httpd configuration will need to be updated for httpd
2.2. For more information, refer to
[8]http://httpd.apache.org/docs/2.2/upgrading.html.

Note that any third-party modules compiled for httpd 2.0 must be
rebuilt for httpd 2.2.

php

Version 5.1 of PHP is now included in Red Hat Enterprise Linux 5,
which includes a number of changes to the language along with
significant performance improvements. Some scripts might need to
be edited for use with the new version; please refer to the link
below for more information on migrating from PHP 4.3 to PHP 5.1:

[9]http://www.php.net/manual/en/migration5.php

The /usr/bin/php executable is now built using the CLI
command-line SAPI, rather than the CGI SAPI. Use /usr/bin/php-cgi
for CGI SAPI. The php-cgi executable also includes FastCGI
support.

The following extension modules have been added:

o the mysqli extension, a new interface designed specifically
for MySQL 4.1 (included in the php-mysql package)

o date, hash, Reflection, SPL and SimpleXML (built-in with the
php package)

o pdo and pdo_psqlite (in the php-pdo package)

o pdo_mysql (in the php-mysql package)

o pdo_pgsql (in the php-pgsql package)

o pdo_odbc (in the php-odbc package)

o soap (in the php-soap package)

o xmlreader and xmlwriter (in the php-xml package)

o dom (replacing the domxml extension in the php-xml package)

The following extension modules are no longer included:

o dbx

o dio

o yp

o overload

o domxml

The PEAR Framework

The PEAR framework is now packaged in the php-pear package. Only
the following PEAR components are included in Red Hat Enterprise
Linux 5:

o Archive_Tar

o Console_Getopt

o XML_RPC

Encrypted Swap Partitions and Non-root File Systems

Red Hat Enterprise Linux 5 now provides basic support for
encrypted swap partitions and non-root file systems. To use these
features, add the appropriate entries to /etc/crypttab and
reference the created devices in /etc/fstab.

Below is a sample /etc/crypttab entry:

my_swap /dev/hdb1 /dev/urandom swap,cipher=aes-cbc-essiv:sha256

This creates the encrypted block device /dev/mapper/my_swap, which
can be referenced in /etc/fstab.

Below is a sample /etc/crypttab entry for a file system volume:

my_volume /dev/hda5 /etc/volume_key cipher=aes-cbc-essiv:sha256

The /etc/volume_key file contains a plaintext encryption key. You
can also specify none as the key file name; this configures the
system to ask for the encryption key during boot instead.

It is recommended to use LUKS (Linux Unified Key Setup) for
setting up file system volumes. To do this, follow these steps:

1. Create the encrypted volume using cryptsetup luksFormat.

2. Add the necessary entry to /etc/crypttab.

3. Set up the volume manually using cryptsetup luksOpen (or
reboot).

4. Create a file system on the encrypted volume.

5. Add the necessary entry to /etc/fstab.

mount and umount

The mount and umount commands no longer directly support NFS; a
built-in NFS client no longer exists. A separate nfs-utils
package, which provides /sbin/mount.nfs and /sbin/umount.nfs
helpers, must be installed for this.

CUPS Printer Browsing

CUPS printer browsing over a local subnet can be configured using
the graphical tool system-config-printer. It can also be done
using the CUPS web interface, [10]http://localhost:631/.

To use directed broadcasts for printer browsing between subnets,
open /etc/cups/cupsd.conf on the clients and replace BrowseAllow
@LOCAL with BrowseAllow ALL.

ATI and R500 Support

ATI graphics cards based on the R500 chipset are supported for the
vesa driver only, and are not supported by Red Hat Enterprise
Linux 5 on external monitors, LCD projectors or accelerated 3D
support.

up2date and yum

up2date is being deprecated in favor of yum (Yellowdog Updater
Modified). As such, it is advisable that you revise any
up2date-dependent scripts your system is using accordingly. For
more information about yum, consult its man page with the command
man yum; you can also consult the installed documentation under
the directories /usr/share/doc/yum-<version> and
/usr/share/doc/yum-metadata-parser-<version> (replace <version>
with the corresponding version of yum and yum-metadata-parser
installed).

OpenLDAP Server and Red Hat Directory Server

Red Hat Directory Server is an LDAP-based server that centralizes
enterprise and network data into an OS-independent, network-based
registry. It is set to replace OpenLDAP server components, which
will be deprecated after Red Hat Enterprise Linux 5. For more
information about Red Hat Directory Server, refer to
[11]http://www.redhat.com/software/rha/directory/.

i810 Driver and i830 Support

The i810 driver supports all integrated Intel graphics chipsets,
from i810 to i965. However, the support for i830 (and newer)
chipsets is limited; the i810 driver can only set modes listed in
the video BIOS. If your machine has an i830 or newer chipset
installed, run the following command to determine what the
available modes are:

grep Mode: /var/log/Xorg.0.log

Modes marked with an asterisk (*) are available for selection.

Many laptop video BIOSes do not supply a mode that matches the
native panel size. Therefore the chosen mode may appear stretched,
distorted, or with black borders. As such, if your chosen mode
does not display properly, you need a BIOS update from your
hardware vendor for the native panel size to work correctly.

Smart Card Login

Red Hat Enterprise Linux 5 includes support for Smart Cards, which
provide secure storage for your key pair and an associated public
key certificate. These keys are protected through a PIN that you
need to input when a key or certificate on the Smart Card is
required.

Deploying Smart Cards in a Red Hat Enterprise Linux 5 environment
allows you to leverage features such as Kerberos and S/MIME to
increase security in relation to authentication. Red Hat
Enterprise Linux 5 supports the following:

o Axalto Cyberflex 32K e-Gate

o DoD CAC Cards

To set up Smart Card authentication, your network will need to be
equipped with Red Hat Directory Server and Red Hat Certificate
System. For more information regarding Smart Cards, refer to the
Red Hat Enterprise Linux Deployment Guide Chapter on Single
Sign-On.

Intel PRO/Wireless 3945ABG Network Connection Support

This release of Red Hat Enterprise Linux 5 includes support for
the ipw3945 (Intel PRO/Wireless 3945ABG Network Connection)
adapter. The Red Hat Enterprise Linux 5 Supplementary disc
contains the driver, regulatory daemon and firmware needed to
support this adapter.

To enable support for the ipw3945 wireless adapter, search the Red
Hat Enterprise Linux 5 Supplementary disc for packages with
filenames containing "3945" and install them.

rawio

rawio is a deprecated interface; however, Red Hat Enterprise Linux
5 still includes support for it. If you have an application that
performs device access using rawio, it is highly recommended that
you modify your application to open the block device with the
O_DIRECT flag. The rawio interface will remain throughout the life
of Red Hat Enterprise Linux 5, but is a candidate for removal in a
future release.

Currently, AIO (Asynchronous I/O) on file systems is only
supported in O_DIRECT or non-buffered mode. Further, note that the
asynchronous poll interface is no longer present, and that AIO on
pipes is no longer supported.

ctmpc

ctmpc is a deprecated driver; however, it will still be included
throughout the life of Red Hat Enterprise Linux 5. Note that it is
a candidate for removal from future releases.

Policy Modules and semanage Support

Red Hat Enterprise Linux 5 now supports policy modules and
semanage. Policy modules simplify the creation and distribution of
policy customizations and third-party policies through the use of
the semodule and checkmodule tools.

The semanage tool is a policy management tool that modifies the
SELinux configuration. It also allows you to configure file
contexts, networking component labeling, and user mappings for
Linux-to-SELinux.

raw Device Mapping

The raw devices interface has been deprecated in Red Hat
Enterprise Linux 5; raw device mapping is now configured via udev
rules.

To configure raw device mapping, add the appropriate entries to
/etc/udev/rules.d/60-raw.rules in the following formats:

o For device names:

ACTION=="add", KERNEL="<device name>", RUN+="raw /dev/raw/rawX %N"

o For major / minor numbers:

ACTION=="add", ENV{MAJOR}="A", ENV{MINOR}="B", RUN+="raw /dev/raw/rawX %M %m"

Replace <device name> with the name of the device you need to bind
(for example, /dev/sda1). "A" and "B" are the major / minor
numbers of the device you need to bind, and X is the raw device
number that you want the system to use.

If you have a large, pre-existing /etc/sysconfig/rawdevices file,
convert it with the following script:

#!/bin/sh

grep -v "^ *#" /etc/sysconfig/rawdevices | grep -v "^$" | while read dev major minor ; do
if [ -z "$minor" ]; then
echo "ACTION==\"add\", KERNEL==\"${major##/dev/}\", RUN+=\"/usr/bin/raw $dev %N\""
else
echo "ACTION==\"add\", ENV{MAJOR}==\"$major\", ENV{MINOR}==\"$minor\", RUN+=\"/usr/bin/raw $dev %M %m\""
fi
done

QLogic Support

Red Hat Enterprise Linux 5 supports the QLogic family of iSCSI HBA
(Host Bus Adapters). At present, only the iSCSI interface to these
boards are supported (using the qla4xxx driver).

In addition, Red Hat does not currently support these boards as
Ethernet NIC, as this capability requires the qla3xxx driver. This
issue will be addressed in an upcoming minor release of Red Hat
Enterprise Linux 5.

IBM System z Instruction Set

In order to optimally exploit the IBM System z instruction set for
31-bit applications, it is recommended that you use the gcc option
-march=z900. For 64-bit applications, the gcc will exploit the IBM
System z instruction set by default.

iSeries Access for Linux

The iSeries ODBC Driver for Linux has been replaced by the iSeries
Access for Linux, which can be downloaded at the following link:

[12]http://www.ibm.com/eserver/iseries/access/linux/

The iSeries Access for Linux offers Linux-based access to iSeries
servers, and allows you to:

o Access the DB2 UDB (Universal Database) for iSeries using its
ODBC Driver

o Establish a 5250 session to an iSeries server from a Linux
client

o Access the DB2 UDB via the EDRS (Extended Dynamic Remote SQL)
driver

o Support 32-bit (i386 and PowerPC) and 64-bit (x86-64 and
PowerPC) platforms

IBM Power4 iSeries

Red Hat Enterprise Linux no longer supports the IBM Power4
iSeries.

Driver Update Program

This section includes information on the implementation of the Red Hat
Enterprise Linux 5 Driver Update Program.

Kernel Module Packages

On Red Hat Enterprise Linux 5, it is possible to build updated
kernel module packages that depend upon the current kernel ABI
version and not on a specific kernel release number. This
facilitates building kernel modules that can be used against a
range of Red Hat Enterprise Linux 5 kernels, rather than a single
release. The project website at [13]http://www.kerneldrivers.org/
contains more information about the packaging process, as well as
several examples.

Note that the following issues have also been identified:

o Bootpath drivers distributed as kmod packages are not
officially supported.

o Overriding existing in-kernel drivers are not currently
supported.

These issues will be addressed in a future update of Red Hat
Enterprise Linux 5.

Kernel Module Loading

The module loading behavior on Red Hat Enterprise Linux 5 has
changed from previous releases of Red Hat Enterprise Linux. The
modules shipped in the Red Hat Enterprise Linux 5 kernel package
are signed, as was the case in Red Hat Enterprise Linux 4. On Red
Hat Enterprise Linux 5 kernels, however, it is no longer possible
to load a signed module from another kernel build.

This means that a module shipped with the initial Red Hat
Enterprise Linux 5 distribution cannot be loaded in future updated
kernels. This helps prevent users from loading unsupported modules
on a system. Red Hat only supports modules that are signed and
included in a distribution.

If you want to load an older module, you can try rebuilding it
without a signature. Alternatively, you can remove the signature
from the binary file using the following command:

objcopy -R .module_sig <module name>-mod.ko <module name>-nosig.ko

It is recommended that you consult with a designated Red Hat
Global Support Representative before attempting to load unsigned
modules.

Internationalization

This section includes information on language support under Red Hat
Enterprise Linux 5.

Input Methods

SCIM (Smart Common Input Method) has replaced IIIMF as the input
method system for Asian and other languages in this release. The
default GTK Input Method Module for SCIM is provided by
scim-bridge; in Qt, it is provided by scim-qtimm.

Below are the default trigger hotkeys for different languages:

o All languages: Ctrl-Space

o Japanese: Zenkaku-Hankaku or Alt-`

o Korean: Shift-Space

If SCIM is installed, it runs by default for all users.

After installing or removing SCIM engine packages, it is
recommended to start a new desktop session in order for the
changes to be reflected in the SCIM language menu.

Language Installation

To enable additional language support for some Asian languages,
you need to install the necessary language support packages. Below
is a list of these languages and the command you need to run (as
root) to install their corresponding language support packages:

o Assamese -- yum install fonts-bengali m17n-db-assamese
scim-m17n

o Bengali -- yum install fonts-bengali m17n-db-bengali
scim-m17n

o Chinese -- yum install fonts-chinese scim-chewing scim-pinyin
scim-tables-chinese

o Gujarati -- yum install fonts-gujarati m17n-db-gujarati
scim-m17n

o Hindi -- yum install fonts-hindi m17n-db-hindi scim-m17n

o Japanese -- yum install fonts-japanese scim-anthy

o Kannada -- yum install fonts-kannada m17n-db-kannada
scim-m17n

o Korean -- yum install fonts-korean scim-hangul

o Malayalam -- yum install fonts-malayalam m17n-db-malayalam
scim-m17n

o Marathi -- yum install fonts-hindi m17n-db-marathi scim-m17n

o Oriya -- yum install fonts-oriya m17n-db-oriya scim-m17n

o Punjabi -- yum install fonts-punjabi m17n-db-punjabi
scim-m17n

o Sinhala -- yum install fonts-sinhala m17n-db-sinhala
scim-m17n

o Tamil -- yum install fonts-tamil m17n-db-tamil scim-m17n

o Telugu -- yum install fonts-telugu m17n-db-telugu scim-m17n

It is also recommended that you install scim-bridge-gtk and
scim-qtimm when enabling additional language support. The
scim-bridge-gtk package prevents possible binary conflicts with
third-party applications linked against older versions of
libstdc++.

Note that additional language support packs are also available for
OpenOffice (openoffice.org-langpack-<language code>_<locale>) and
KDE (kde-i18n-<language>). These packages can also be installed
through yum.

im-chooser

A new user configuration tool called im-chooser has been added,
which allows you to easily disable or enable the usage of input
methods on your desktop. So if SCIM is installed but you do not
wish to run it on your desktop, you can disable it using
im-chooser.

xinputrc

At X startup, xinput.sh now sources ~/.xinputrc or
/etc/X11/xinit/xinputrc instead of searching config files under
~/.xinput.d/ or /etc/xinit/xinput.d/.

Pango Support in Firefox

Firefox in Red Hat Enterprise Linux 5 is built with Pango, which
provides better support for certain scripts, such as Indic and
some CJK scripts.

To disable the use of Pango, set MOZ_DISABLE_PANGO=1 in your
environment before launching Firefox.

Fonts

Support is now available for synthetic emboldening of fonts that
do not have a bold face.

New fonts for Chinese have been added: AR PL ShanHeiSun Uni
(uming.ttf) and AR PL ZenKai Uni (ukai.ttf). The default font is
AR PL ShanHeiSun Uni, which contains embedded bitmaps. If you
prefer outline glyphs, add the following section to your
~/.font.conf file:

<fontconfig>
<match target="font">
<test name="family" compare="eq">
<string>AR PL ShanHeiSun Uni</string>
</test>
<edit name="embeddedbitmap" mode="assign">
<bool>false</bool>
</edit>
</match>
</fontconfig>

gtk2 IM submenu

The Gtk2 context menu IM submenu no longer appears by default. You
can enable it on the command line with the following command:

gconftool-2 --type bool --set
'/desktop/gnome/interface/show_input_method_menu' true

Support for text installation on CJK

CJK (Chinese, Japanese, and Korean) rendering support has been
removed from the Anaconda text installation. The text installation
method is being deprecated in the long term, as the GUI
installation, VNC and kickstart methods are preferred.

gtk+ deprecation

The following packages are deprecated and scheduled for removal in
Red Hat Enterprise Linux:

o gtk+

o gdk-pixbuf

o glib

These packages are being deprecated in favor of the gtk2 stack,
which offers better functionality particularly in terms of
internationalization and font handling.

CJK input on console

If you need to display Chinese, Japanese, or Korean text on the
console, you need to set up a framebuffer; afterwards, install
bogl-bterm, and run bterm on the framebuffer.

Kernel Notes

This section notes the differences between 2.6.9 (on which Red Hat
Enterprise Linux 4 is based) and 2.6.18 (which Red Hat Enterprise Linux 5
will inherit) as of July 12, 2006. Additional features which we are
currently working on upstream (for example, virtualization) that will
appear late in 2.6.18 or 2.6.19 are not highlighted here. In other words,
this list only shows what is already included in the upstream Linus tree;
not what is currently in development. Consequently, this list is not a
final, or complete list of the new Red Hat Enterprise Linux 5 features,
although it does give a good overview of what can be expected. Also, note
that this section only picks out highlights of upstream changes, and as
such it is not fully comprehensive. It does not include mention of several
low-level hardware support enhancements and device driver info.

The following is a good source for a next level-of-detail view:

[14]http://kernelnewbies.org/LinuxChanges

Performance / Scalability

o Big Kernel Lock preemption (2.6.10)

o Voluntary preemption patches (2.6.13) (subset in Red Hat
Enterprise Linux 4)

o Lightweight user-space priority inheritance (PI) support for
futexes, useful for real-time applications (2.6.18)

o ref: [15]http://lwn.net/Articles/178253/

o New 'mutex' locking primitive (2.6.16)

o High resolution timers (2.6.16)

o In contrast to the low-resolution timeout API
implemented in kernel/timer.c, hrtimers provide finer
resolution and accuracy depending on system
configuration and capabilities. These timers are
currently used for itimers, POSIX timers, nanosleep and
precise in-kernel timing.

o Modular, on-the-fly switchable I/O schedulers (2.6.10)

o This was adjustable only by boot option in Red Hat
Enterprise Linux 4 (also system-wide instead of
per-queue).

o Conversion to 4-level page tables (2.6.11)

o allows x86-64 to increase from 512G to 128TB of memory

o New Pipe implementation (2.6.11)

o 30-90% performance improvement in pipe bandwidth

o circular buffer allows more buffering than blocking
writers

o "Big Kernel Semaphore": turns the Big Kernel Lock into a
semaphore

o reduces latency by breaking up long lock hold times and
adding voluntary preemption

o X86 "SMP alternatives"

o optimizes a single kernel image at runtime according to
the available platform

o ref: [16]http://lwn.net/Articles/164121/

o libhugetlbfs

o allows applications to use the huge page support in
Linux with no need for source code modification

o kernel-headers package

o replaces the glibc-kernheaders package

o provides better suitability with the new headers_install
feature of the 2.6.18 kernel

o notable kernel header-related changes:

o removed <linux/compiler.h> header file, as it is no
longer useful

o removed _syscallX() macros; user-space should use
syscall() from the C library instead

o removed <asm/atomic.h> and <asm/bitops.h> header
files; C compiler provides its own atomic built-in
functions better suitable for user-space programs

o content previously protected with #ifdef __KERNEL__
is now removed completely with the unifdef tool;
defining __KERNEL__ in order to view parts which
should not be visible to user-space is no longer
effective

o removed the PAGE_SIZE macro from some
architectures, due to variance in page sizes;
user-space should be using sysconf (_SC_PAGE_SIZE)
or getpagesize()

o to provide better suitability for user-space, removed
several header files and header content

Generic Feature Additions

o kexec and kdump (2.6.13)

o diskdump and netdump have been replaced by kexec and
kdump, which ensure faster boot-up and creation of
reliable kernel vmcores for diagnostic purposes. For
more information and configuration instructions, please
refer to
/usr/share/doc/kexec-tools-<version>/kexec-kdump-howto.txt
(replace <version> with the corresponding version of the
kexec-tools package installed).

o Note that at present, virtualized kernels cannot use the
kdump function.

o inotify (2.6.13)

o user interface for this is through the following
syscalls: sys_inotify_init, sys_inotify_add_watch, and
sys_inotify_rm_watch.

o Process Events Connector (2.6.15)

o reports fork, exec, id change, and exit events for all
processes to user-space.

o Applications that may find these events useful include
accounting / auditing (for example, ELSA), system
activity monitoring (for example, top), security, and
resource management (for example, CKRM). Semantics
provide the building blocks for features like
per-user-namespace, "files as directories" and versioned
file systems.

o Generic RTC (RealTime Clock) subsystem (2.6.17)

o splice (2.6.17)

o new IO mechanism which avoids data copies when
transferring data between applications

o ref: [17]http://lwn.net/Articles/178199/

File System / LVM

o EXT3

o support for Extended Attributes in the body of large
inode in ext3: saves space and improves performance in
some cases (2.6.11)

o Device mapper multipath support

o ACL support for NFSv3 and NFSv4 (2.6.13)

o NFS: supports large reads and writes on the wire (2.6.16)

o The Linux NFS client now supports transfer sizes of up
to 1MB.

o VFS changes

o The "shared subtree" patches have been merged. (2.6.15)

o ref: [18]http://lwn.net/Articles/159077/

o Big CIFS update (2.6.15)

o features several performance improvements as well as
support for Kerberos and CIFS ACL

o autofs4: updated to provide direct mount support for
user-space autofs (2.6.18)

o cachefs core enablers (2.6.18)

Security

o Multilevel security implementation for SELinux (2.6.12)

o Audit subsystem

o support for process-context based filtering (2.6.17)

o more filter rule comparators (2.6.17)

o TCP/UDP getpeercon: enabled security-aware applications to
retrieve the entire security context of a process on the
other side of a socket using an IPSec security association.
If only MLS-level information is needed or interoperability
with legacy unix system is required, NetLabel can be used in
place of IPSec.

Networking

o Added several TCP congestion modules (2.6.13)

o IPv6: supports several new sockopt / ancillary data in
Advanced API (2.6.14)

o IPv4/IPv6: UFO (UDP Fragmentation Offload) Scatter-gather
approach (2.6.15)

o UFO is a feature wherein the Linux kernel network stack
will offload the IP fragmentation functionality of large
UDP datagram to hardware. This will reduce the overhead
of stack in fragmenting the large UDP datagram to
MTU-sized packets.

o Added nf_conntrack subsystem (2.6.15)

o The existing connection tracking subsystem in netfilter
can only handle ipv4. There were two choices present to
add connection tracking support for ipv6; either
duplicate all of the ipv4 connection tracking code into
an ipv6 counterpart, or (the choice taken by these
patches) design a generic layer that could handle both
ipv4 and ipv6 and thus requiring only one sub-protocol
(TCP, UDP, etc.) connection tracking helper module to be
written. In fact, nf_conntrack is capable of working
with any layer 3 protocol.

o IPV6

o RFC 3484-compliant source address selection (2.6.15)

o added support for Router Preference (RFC4191) (2.6.17)

o added Router Reachability Probing (RFC4191) (2.6.17)

o added support for Multiple Routing Tables and Policy
Routing

o Wireless updates

o hardware crypto and fragmentation offload support

o QoS (WME) support, "wireless spy support"

o mixed PTK/GTK

o CCMP/TKIP support and WE-19 HostAP support

o BCM43xx wireless driver

o ZD1211 wireless driver

o WE-20, version 20 of the Wireless Extensions (2.6.17)

o added the hardware-independent software MAC layer, "Soft
MAC" (2.6.17)

o added LEAP authentication type

o Added generic segmentation offload (GSO) (2.6.18)

o can improve performance in some cases, though it needs
to be enabled through ethtool

o DCCPv6 (2.6.16)

Added Hardware Support

Note

This section only enumerates the most generic features among many.

o x86-64 clustered APIC support (2.6.10)

o Infiniband support (2.6.11)

o Hot plug

o added generic memory add/remove and supporting functions
for memory hotplug (2.6.15)

o SATA/libata enhancements, additional hardware support

o A completely reworked libata error handler; the result
of all this work should be a more robust SATA subsystem
which can recover from a wider range of errors.

o Native Command Queuing (NCQ), the SATA version of tagged
command queuing - the ability to have several I/O
requests to the same drive outstanding at the same time.
(2.6.18)

o Hotplug support (2.6.18)

o EDAC support (2.6.16)

o The EDAC goal is to detect and report errors that occur
within the system.

o Added a new ioatdma driver for the Intel(R) I/OAT DMA engine
(2.6.18)

NUMA (Non-Uniform Memory Access) / Multi-core

o Cpusets (2.6.12)

o Cpusets now provide a mechanism for assigning a set of
CPUs and Memory Nodes to a set of tasks. Cpusets
constrain the CPU and memory placement of tasks only to
the resources within a task's current cpuset. These are
essential in managing dynamic job placement on large
systems.

o NUMA-aware slab allocator (2.6.14)

o This creates slabs on multiple nodes and manages slabs
in such a way that locality of allocations is optimized.
Each node has its own list of partial, free and full
slabs. All object allocations for a node occur from
node-specific slab lists.

o Swap migration (2.6.16)

o Swap migration allows the moving of physical location of
pages between nodes in a NUMA system while the process
is running.

o Huge pages (2.6.16)

o Added NUMA policy support for huge pages: the
huge_zonelist() function in the memory policy layer
provides a list of zones ordered by NUMA distance. The
hugetlb layer will walk that list looking for a zone
that has available huge pages but is also in the nodeset
of the current cpuset.

o Huge pages now obey cpusets.

o Per-zone VM counters

o provide zone-based VM statistics, which are necessary in
determining what state of memory a zone is in

o Netfilter ip_tables: NUMA-aware allocation. (2.6.16)

o Multi-core

o Added a new scheduler domain for representing multi-core
with shared caches between cores. This makes it possible
to make smarter cpu scheduling decisions on such
systems, improving performance greatly for some cases.
(2.6.17)

o Power saving policy for the CPU scheduler: with
multicore/smt cpus, the power consumption can be
improved by leaving some packages idle while others do
all the work, instead of spreading the tasks over all
CPUs.

( amd64 )

--------------

^[[19]1] This material may be distributed only subject to the terms and
conditions set forth in the Open Publication License, v1.0, available at
[20]http://www.opencontent.org/openpub/.

References

Visible links
1. file:///home/ddomingo/cvs/docs-stuff/readmes/RHEL5/RELEASE-NOTES-x86_64-en.html#ftn.id3408157
2. http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/index.html
3. http://www.redhat.com/rhel/
4. http://www.redhat.com/apps/support/in.html
5. http://fedoraproject.org/wiki/StatelessLinuxHOWTO
6. mailto:stateless-list@redhat.com
7. http://people.redhat.com/dledford/Infiniband/openmpi
8. http://httpd.apache.org/docs/2.2/upgrading.html
9. http://www.php.net/manual/en/migration5.php
10. http://localhost:631/
11. http://www.redhat.com/software/rha/directory/
12. http://www.ibm.com/eserver/iseries/access/linux/
13. http://www.kerneldrivers.org/
14. http://kernelnewbies.org/LinuxChanges
15. http://lwn.net/Articles/178253/
16. http://lwn.net/Articles/164121/
17. http://lwn.net/Articles/178199/
18. http://lwn.net/Articles/159077/
19. file:///home/ddomingo/cvs/docs-stuff/readmes/RHEL5/RELEASE-NOTES-x86_64-en.html#id3408157
20. http://www.opencontent.org/openpub/