Copyright (c) 2007 Red Hat, Inc. and others ^[[1]1]

Copyright (c) 2007 Red Hat, Inc. and others ^[[1]1]

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Introduction

The following topics are covered in this document:

o Installation-Related Notes

o Feature Updates

o Driver Updates

o Kernel-Related Updates

o Other Updates

o Technology Previews

o Resolved Issues

o Known Issues

Some updates on Red Hat Enterprise Linux 5.1 may not appear in this
version of the Release Notes. An updated version may also be available at
the following URL:

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

Installation-Related Notes

This section includes information specific to Anaconda and the
installation of Red Hat Enterprise Linux 5.1.

In order to upgrade an already-installed Red Hat Enterprise Linux 5, 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 5.1 or to perform an upgrade from the latest updated version of Red
Hat Enterprise Linux 5 to Red Hat Enterprise Linux 5.1.

o 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.

The contents of the Supplementary CD-ROM and other layered product
CD-ROMs must be installed after Red Hat Enterprise Linux 5.1 has been
installed.

o When installing Red Hat Enterprise Linux 5.1 on a fully virtualized
guest, do not use the kernel-xen kernel. Using this kernel on fully
virtualized guests can cause your system to hang.

If you are using an Installation Number when installing Red Hat
Enterprise Linux 5.1 on a fully virtualized guest, be sure to deselect
the Virtualization package group during the installation. The
Virtualization package group option installs the kernel-xen kernel.

Note that paravirtualized guests are not affected by this issue.
Paravirtualized guests always use the kernel-xen kernel.

o If you are using the Virtualized kernel when upgrading from Red Hat
Enterprise Linux 5 to 5.1, you must reboot after completing the
upgrade.

The hypervisors of Red Hat Enterprise Linux 5 and 5.1 are not
ABI-compatible. If you do not reboot between upgrades, the upgraded
Virtualization RPMs will not match the running kernel.

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

iSCSI installation and boot was originally introduced in Red Hat
Enterprise Linux 5 as a Technology Preview. This feature is now fully
supported, with the restrictions described below.

This capability has three configurations depending on whether you are:

o using a hardware iSCSI initiator (such as the QLogic qla4xxx)

o using the open-iscsi initiator on a system with firmware boot support
for iSCSI (such as iSCSI Boot Firmware, or a version of Open Firmware
that features the iSCSI boot capability)

o using the open-iscsi initiator on a system with no firmware boot
support for iSCSI

Using a Hardware iSCSI Initiator

If you are using a hardware iSCSI initiator, you can use the card's BIOS
set-up utility to enter the IP address and other parameters required to
obtain access to the remote storage. The logical units of the remote
storage will be available in Anaconda as standard sd devices, with no
additional set-up required.

If you need to determine the initiator's qualified name (IQN) in order to
configure the remote storage server, follow these steps during
installation:

1. Go to the installer page where you select which disk drives to use for
the installation.

2. Click on Advanced storage configuration.

3. Click on Add iSCSI target.

4. The iSCSI IQN will be displayed on that screen.

Using open-iscsi On A System With Firmware Boot Support for iSCSI

If you are using the open-iscsi software initiator on a system with
firmware boot support for iSCSI, use the firmware's setup utility to enter
the IP address and other parameters needed to access the remote storage.
Doing this configures the system to boot from the remote iSCSI storage.

Currently, Anaconda does not access the iSCSI information held by the
firmware. Instead, you must manually enter the target IP address during
installation. To do so, determine the IQN of the initiator using the
procedure described above. Afterwards, on the same installer page where
the initiator IQN is displayed, specify the IP address of the iSCSI target
you wish to install to.

After manually specifying the IP address of the iSCSI target, the logical
units on the iSCSI targets will be available for installation. The initrd
created by Anaconda will now obtain the IQN and IP address of the iSCSI
target.

If the IQN or IP address of the iSCSI target are changed in the future,
enter the iBFT or Open Firmware set-up utility on each initiator and
change the corresponding parameters. Afterwards, modify the initrd (stored
in the iSCSI storage) for each initiator as follows:

1. Expand the initrd using gunzip.

2. Unpack it using cpio -i.

3. In the init file, search for the line containing the string
iscsistartup. This line also contains the IQN and IP address of the
iSCSI target; update this line with the new IQN and IP address.

4. Re-pack the initrd using cpio -o.

5. Re-compress the initrd using gunzip.

The ability of the operating system to obtain iSCSI information held by
the Open Firmware / iBFT firmware is planned for a future release. Such an
enhancement will remove the need to modify the initrd (stored in the iSCSI
storage) for each initiator whenever the IP address or IQN of the iSCSI
target is changed.

Using open-iscsi On A System With No Firmware Boot Support for iSCSI

If you are using the open-iscsi software initiator on a system with no
firmware boot support for iSCSI, use a network boot capability (such as
PXE/tftp). In this case, follow the same procedure described earlier to
determine the initiator IQN and specify the IP address of the iSCSI
target. Once completed, copy the initrd to the network boot server and set
up the system for network boot.

Similarly, if the IP address or IQN of the iSCSI target is changed, the
initrd should be modified accordingly as well. To do so, use the same
procedure described earlier to modify the initrd for each initiator.

Feature Updates

EXT3 Enhancement

The maximum capacity of the EXT3 is now 16TB (increased from 8TB).
This enhancement was originally included in Red Hat Enterprise
Linux 5 as a Technology Preview, and is now fully supported in
this update.

yum-security

It is now possible to limit yum to install security updates only.
To do so, simply install the yum-security plugin and run the
following command:

yum update --security

Anaconda layer 2 Mode Enhancement

Restarting a Resource Independently

It is now possible to restart a resource in a cluster without
interrupting its parent service. This can be configured in
/etc/cluster/cluster.conf on a running node using the
__independent_subtree="1" attribute to tag a resource as
independent.

For example:

<service name="example">
<fs name="One" __independent_subtree="1" ...>
<nfsexport ...>
<nfsclient .../>
</nfsexport>
</fs>
<fs name="Two" ...>
<nfsexport ...>
<nfsclient .../>
</nfsexport>
<script name="Database" .../>
</fs>
<ip/>
</service>

Here, two file system resources are used: One and Two. If One
fails, it is restarted without interrupting Two. If Two fails, all
components (One, children of One and children of Two) are
restarted. At no given time are Two and its children dependent on
any resource provided by One.

Note that Samba requires a specific service structure, and as such
it cannot be used in a service with independent subtrees. This is
also true for several other resources, so use the
__independent_subtree="1" attribute with caution.

Virtualization

The following Virtualization updates are also included in this
release:

o The virtualized kernel can now use the kdump function.

o AMD-V is now supported in this release. This enables live
domain migration for fully virtualized guests.

o The virtualized kernel can now support up to 256GB of RAM.

o The in-kernel socket API is now expanded. This was done to
fix a bug that occurs when running sctp between guests.

o Virtual networking is now part of libvirt, the virtualization
library. libvirt has a set of commands that sets up a virtual
NAT/router and private network for all local guests on a
machine. This is especially useful for guests that do not
need to be routable from the outside. It is also useful for
developers who use Virtualization on laptops.

Note that the virtual networking capability adds a dependency
on dnsmasq, which handles dhcp for the virtual network.

For more information about libvirt, refer to
[3]http://libvirt.org.

o libvirt can now manage inactive virtual machines. libvirt
does this by defining and undefining domains without stopping
or starting them. This functionality is similar to the virsh
define and virsh undefine commands.

This enhancement allows the Red Hat Virtual Machine Manager
to display all available guests. This allows you to start
these guests directly from the GUI.

o Installing the kernel-xen package no longer leads to the
creation of incorrect / incomplete elilo.conf entries.

o Fully virtualized guests now support hot-migration.

o The xm create command now has a graphical equivalent in
virt-manager.

o Nested Paging (NP) is now supported. This feature reduces the
complexity of memory management in virtualized environments.
In addition, NP also reduces CPU utilization in
memory-intensive guests.

At present, NP is not enabled by default. If your system
supports NP, it is recommended that you enable NP by booting
the hypervisor with the parameter hap=1.

This update to the Virtualization feature also includes the
capability to install and run paravirtualized 32-bit guests on
64-bit hosts. However, this capability is provided as a Technology
Preview; as such, it is not supported for production use.

Shared Page Tables

Shared page tables are now supported for hugetlb memory. This
enables page table entries to be shared among multiple processes.

Sharing page table entries among multiple processes consumes less
cache space. This improves application cache hit ratio, resulting
in better application performance.

tick_divider

The tick_divider=<value> option is a sysfs parameter that allows
you to adjust the system clock rate while maintaining the same
visible HZ timing value to user space applications.

Using the tick_divider= option allows you to reduce CPU overhead
and increase efficiency at the cost of lowering the accuracy of
timing operations and profiling.

Useful <values> for the standard 1000Hz clock are:

o 2 = 500Hz

o 4 = 250Hz

o 5 = 200Hz

o 8 = 125Hz

o 10 = 100Hz (value used by previous releases of Red Hat
Enterprise Linux)

Note that the virtualized kernel does not support multiple timer
rates on guests. dom0 uses a fixed timing rate set across all
guests; this reduces the load that multiple tick rates could
cause.

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.

This feature was originally introduced in Red Hat Enterprise Linux
5 as a Technology Preview, and is now fully supported in this
release.

Note that dm-multipath also features inbox support for the Dell
MD3000. However, multiple nodes that use dm-multipath to access
the MD3000 cannot perform immediate failback.

Further, it is recommended that you use the Custom Partitioning
interface in Anaconda if your system has both multipath and
non-multipath devices. Using Automatic Partitioning in such cases
may create both types of devices in the same logical volume
groups.

At present, the following restrictions apply to this feature:

o If there is only one path to the boot Logical Unit Number
(LUN), Anaconda installs to the SCSI device even if mpath is
specified. Even after you enable multiple paths to the boot
LUN and recreate the initrd, the operating system will boot
from the SCSI device instead of the dm-multipath device.

However, if there are multiple paths to the boot LUN to begin
with, Anaconda will correctly install to the corresponding
dm-multipath device after mpath is specified in the kernel
boot line.

o By default, user_friendly_names is set to yes in
multipath.conf. This is a required setting in the support
implementation of the dm-multipath root device. As such,
setting user_friendly_names to no and recreating the initrd
will result in a boot failure with the following error:

Checking filesystems
fsck.ext3: No such file or directory while trying to open /dev/mapper/mpath0p1

Booting from Storage Area Network (SAN)

The ability to boot from a SAN disk device is now supported. In
this case, SAN refers to a Fibre Channel or iSCSI interface. This
capability also features support for system-to-storage connection
through multiple paths using dm-multipath.

In configurations that use multiple host bus adapters (HBA), you
may need to set the system BIOS to boot from another adapter if
all paths through the current adapter fail.

nfsroot

nfsroot is fully supported in this update. This allows users to
run Red Hat Enterprise Linux 5.1 with its root file system (/)
mounted via NFS.

nfsroot was originally introduced in Red Hat Enterprise Linux 5 as
a subset of the Technology Preview feature Stateless Linux. The
full implementation of Stateless Linux remains a Technology
Preview.

At present, nfsroot has the following restrictions:

o Each client must have its own separate root file system over
the NFS server. This restriction applies even when read-only
root is in use.

o SWAP is not supported over NFS.

o SELinux cannot be enabled on nfsroot clients. In general, Red
Hat does not recommend disabling SELinux. As such, customers
must carefully consider the security implications of this
action.

Refer to the following procedure on how to set up nfsroot. This
procedure assumes that your network device is eth0 and the
associated network driver is tg3. You may need to adjust according
to your system configuration:

1. Create the initrd in your home directory using the following
command:

mkinitrd --with=tg3 --rootfs=nfs --net-dev=eth0
--rootdev=<nfs server ip>:/<path to nfsroot>
~/initrd-<kernel-version>.img <kernel-version>

This initrd must be created using the Red Hat Enterprise
Linux 5.1 kernel.

2. Next, create a zImage.initrd image from the initrd generated
earlier. zImage.initrd is a compressed kernel and initrd in
one image. Use the following command:

mkzimage /boot/System.map-<kernel-version>
~/initrd-<kernel-version>.img
/usr/share/ppc64-utils/zImage.stub
~/zImage.initrd-<kernel-version>

3. Copy the created zImage.initrd-<kernel-version> to an
exportable location on your tftp server.

4. Ensure that the exported nfsroot file system on the nfs
server contains the necessary binaries and modules. These
binaries and modules must correspond to the version of the
kernel used to create the initrd in the first step.

5. Configure the DHCP server to point the client to the target
zImage.initrd-<kernel-version>.

To do this, add the following entries to the /etc/dhcpd.conf
file of the DHCP server:

next-server <tftp hostname/IP address>;
filename "<tftp-path>/zImage.initrd";

Note that <tftp-path> should specify the path to the
zImage.initrd from within the tftp-exported directory. For
example, if the absolute path to the zImage.initrd is
/tftpboot/mykernels/zImage.initrd and /tftpboot/ is the
tftp-exported directory, then <tftp-path> should be
mykernels/zImage.initrd.

6. Finally, set your system's boot configuration parameters to
make it boot first from the network device (in this example,
the network device is eth0).

GFS2

GFS2 is an incremental advancement of GFS. This update applies
several significant improvements that require a change to the
on-disk file system format. GFS file systems can be converted to
GFS2 using the utility gfs2_convert, which updates the metadata of
a GFS file system accordingly.

GFS2 was originally released in Red Hat Enterprise Linux 5 as a
Technology Preview, and is now fully supported in this update.
Benchmark tests indicate faster performance on the following:

o heavy usage in a single directory and faster directory scans
(Postmark benchmark)

o synchronous I/O operations (fstest benchmark test indicates
improved performance for messaging applications like TIBCO)

o cached reads, as there is no longer any locking overhead

o direct I/O to preallocated files

o NFS file handle lookups

o df, as allocation information is now cached

In addition, GFS2 also features the following changes:

o journals are now plain (though hidden) files instead of
metadata. Journals can now be dynamically added as additional
servers mount a file system.

o quotas are now enabled and disabled by the mount option
quota=<on|off|account>

o quiesce is no longer needed on a cluster to replay journals
for failure recovery

o nanosecond timestamps are now supported

o similar to ext3, GFS2 now supports the data=ordered mode

o attribute settings lsattr() and chattr() are now supported
via standard ioctl()

o file system sizes above 16TB are now supported

o GFS2 is a standard file system, and can be used in
non-clustered configurations

Driver Update Program

The Driver Update Program (DUP) was designed to allow third-party
vendors (such as OEMs) to add their own device drivers and other
Linux Kernel Modules to Red Hat Enterprise Linux 5 systems using
regular RPM packages as the distribution containers.

Red Hat Enterprise Linux 5.1 applies several updates to the DUP,
most notably:

o install-time Driver Update RPMs through Driver Update Disks
is now supported

o bootpath Driver Updates affecting the system bootpath are now
supported

o support for third-party packaging of Advanced Linux Sound
Architecture (ALSA) is now deprecated

Further, various updates were applied to the approved kernel ABI
symbol whitelists. These whitelists are used by packaging drivers
to determine which symbols and data structures provided by the
kernel can be used in a third-party driver.

For more information, refer to
[4]http://www.kerneldrivers.org/RedHatKernelModulePackages.

Driver Updates

General Driver Updates

o acpi: updated ibm_acpi module to address several ACPI and
docking station issues with Lenovo laptops.

o ipmi: Polling kthread no longer runs when hardware interrupt
is assigned to a Baseboard Management Controller.

o sata: SATA/SAS upgraded to version 2.6.22-rc3.

o openib and openmpi: upgraded to OFED (OpenFabrics Enterprise
Distribution) version 1.2.

o powernow-k8: upgraded to version 2.0.0 to fully support
Greyhound.

o xinput: added to enable full RSA support.

o aic94xx: upgraded to version 1.0.2-1, in line with an upgrade
of the embedded sequencer firmware to v17. These updates
apply the following changes:

o fixed ascb race condition on platforms with expanders

o added REQ_TASK_ABORT and DEVICE_RESET handlers

o physical ports are now cleaned up properly after a
discovery error

o phys can now be enabled and disabled through sysfs

o extended use of DDB lock to prevent race condition of
DDB

Audio

ALSA updated to version 1.0.14. This update applies the following
fixes:

o fixed noise problem on the IBM Taroko (M50)

o Realtek ALC861 is now supported

o fixed a muting problem on xw8600 and xw6600

o ADI 1884 Audio is now supported

o fixed an audio configuration problem on xw4600

PCI

o added function calls to set maximum read request size for
PCIX and PCI-Express

o IBM System P machines now support PCI-Express hotplugging

o added necessary drivers and PCI ID to support SB600 SMBus

Network

o e1000 driver: updated to version 7.3.20-k2 to support
I/OAT-enabled chipsets.

o bnx2 driver: updated to version 1.5.11 to support 5709
hardware.

o B44 ethernet driver: backported from upstream version
2.6.22-rc4 to apply the following changes:

o several endianness fixes were made

o DMA_30BIT_MASK constant is now used

o skb_copy_from_linear_data_offset() is now used

o spin_lock_irqsave() now features safer interrupt
disabling

o simple error checking is performed during resume

o several fixes to multicast were applied

o chip reset now takes longer than previously anticipated

o Marvell sky2 driver: updated to version 1.14 to fix a bug
that causes a kernel panic if the ifup/ifdown commands are
executed repeatedly.

o forcedeth-0.60 driver: now included in this release. This
applies several critical bug fixes for customers using
NVIDIA's MCP55 motherboard chipsets and corresponding onboard
NIC.

o ixgb driver: updated to the latest upstream version
(1.0.126).

o netxen_nic driver: version 3.4.2-2 added to enable support
for NetXen 10GbE network cards.

o Chelsio 10G Ethernet Network Controller is now supported.

o added support for PCI error recovery to the s2io device.

o Broadcomm wireless ethernet driver now supports PCI ID for
nx6325 card.

o fixed a bug that caused an ASSERTION FAILED error when
attempting to start a BCM4306 via ifup.

o ixgb driver: updated to add EEH PCI error recovery support
for the Intel 10-gigabit ethernet card. For more information,
refer to /usr/share/doc/kernel-doc-<kernel
version>/Documentation/pci-error-recovery.txt.

o qla3xxx driver: re-enabled and updated to version 2.03.00-k3
to provide networking support for QLogic iSCSI adapters
without using iSCSI.

o Intel PRO/Wireless 3945ABG network driver: updated to version
1.2.0. This update resolves several issues, including a soft
lockup bug that could occur under certain circumstances on
some laptops.

o qla2xxx: driver upgraded to version 8.01.07-k6. This applies
several changes, most notably:

o iIDMA is now supported

o the following Fibre Channel attributes are now
supported:

o symbolic nodename

o system hostname

o fabric name

o host port state

o trace-control async events are no longer logged

o reset handling logic has been corrected

o MSI-X is now supported

o IRQ-0 assignments are now handled per system

o NVRAM updates immediately go into effect

IPMI

This release includes an update of the IPMI driver set to include
the upstream changes as of version 2.6.21.3, with some patches
included from 2.6.22-rc-4. This update features the following
changes (among others):

o fixed uninitialized data bug in ipmi_si_intf

o kipmid is no longer started if another driver supports
interrupts

o users are now allowed to override the kernel daemon enable
through force_kipmid

o per-channel command registration is now supported

o MAX_IPMI_INTERFACES is no longer used

o hot system interface removal is now supported

o added a Maintenance Mode to support firmware updates

o added poweroff support for the pigeonpoint IPMC

o BT subdriver can now survive long timeouts

o added pci_remove handling for proper cleanup on a hot remove

For information about new module parameters, refer to
/usr/share/doc/kernel-doc-<kernel version>/Documentation/IPMI.txt.

SCSI

o ported SCSI blacklist from Red Hat Enterprise Linux 4 to this
release.

o added PCI IDs for aic79xx driver.

o aacraid driver: updated to version 1.1.5-2437 to support
PRIMERGY RX800S2 and RX800S3.

o megaraid_sas driver: updated to version 3.10. This update
defines the entry point for bios_param, adds an IOCTL memory
pool, and applies several minor bug fixes.

o Emulex lpfc driver: updated to version 8.1.10.9. This update
applies several changes, most notably:

o fixed host_lock management in the ioctl paths

o the AMD chipset is now automatically detected, and
reduced the DMA length to 1024 bytes

o nodes are no longer removed during dev_loss_tmo if
discovery is active

o 8GB link speeds are now enabled

o qla4xxx driver updated to apply the following changes:

o added support for IPV6, QLE406x and ioctl module

o fixed a mutex_lock bug that could cause lockups

o resolved lockup issues of qla4xxx and qla3xxx when
attempting to load/unload either interface

o mpt fusion drivers: updated to version 3.04.04. This update
applies several changes, most notably:

o fixed several error handling bugs

o mptsas now serializes target resets

o mptsas and mptfc now support LUNs and targets greater
than 255

o fixed an LSI mptspi driver regression that resulted in
extremely slow DVD driver performance

o when an LSI SCSI device returns a BUSY status, I/O
attempts no longer fail after several retries

o RAID arrays are no longer unavailable after auto-rebuild

o arcmsr driver: included to provide support for Areca RAID
controllers.

o 3w-9xxx module: updated to correctly support 3ware 9650SE.

Kernel-Related Updates

o The CIFS client has been updated to version 1.48aRH. This is based
upon the 1.48a release, with patches that apply the following changes:

o the mount option sec=none results in an anonymous mount

o CIFS now honors the umask when POSIX extensions are enabled

o fixed sec= mount options that request packet signing

Note that for users of the EMC Celerra product (NAS Code 5.5.26.x and
below), the CIFS client hangs when accessing shares on EMC NAS. This
issue is characterized by the following kernel messages:

kernel: CIFS VFS: server not responding
kernel: CIFS VFS: No response for cmd 162 mid 380
kernel: CIFS VFS: RFC1001 size 135 bigger than SMB for Mid=384

After a CIFS mount, it becomes impossible to read/write any file on it
and any application that attempts an I/O on the mountpoint will hang.
To resolve this issue, upgrade to NAS Code 5.5.27.5 or later (use EMC
Primus case number emc165978).

o MODULE_FIRMWARE tags are now supported.

o ICH9 controllers are now supported.

o Greyhound processors are now supported in CPUID calls.

o Oprofile now supports new Greyhound performance counter events.

o Directed DIAG is now supported to improve z/VM utilization.

o The Intel graphics chipset is now supported through the DRM kernel
module. Further, the DRM API has been upgraded to version 1.3 to
support direct rendering.

o Updates to ACPI power management have improved S3 suspend-to-RAM and
S4 hibernate.

Other Updates

o gaim is now called pidgin.

o Intel microcode updated to version 1.17. This adds support for new
Intel processors.

o Implicit active-active failover using dm-multipath on EMC Clariion
storage is now supported.

o The Chinese font Zysong is no longer installed as part of the
fonts-chinese package. Zysong is now packaged separately as
fonts-chinese-zysong. The fonts-chinese-zysong package is located in
the Supplementary CD.

Note that the fonts-chinese-zysong package is needed to support the
Chinese National Standard GB18030.

o The Challenge Handshake Authentication Protocol (CHAP) username and
password have a character limit of 256 each.

o pump is deprecated in this update. As such, configuring your network
interface through netconfig may result in broken ifcfg scripts.

To properly configure your network interface, use
system-config-network instead. Installing the updated
system-config-network package removes netconfig.

o rpm --aid is no longer supported. It is recommended that you use yum
when updating and installing packages.

Technology Previews

Technology Preview features are currently not supported under Red Hat
Enterprise Linux 5.1 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

Stateless Linux is a new way of thinking about how a system should
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 (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 remains as
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][email protected].

The enabling infrastructure pieces for Stateless Linux were
originally introduced in 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.

devicescape (d80211)

The devicescape stack enables the iwlwifi 4965GN wireless driver.
This stack allows certain wireless devices to connect to any Wi-Fi
network.

This stack has a code base that is yet to be accepted upstream. In
addition, the stability of this stack is yet to be conclusively
verified through testing. As such, this stack is included in this
release as a Technology Preview.

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.

Systemtap

Systemtap provides free software (GPL) infrastructure to simplify
the gathering of information about the running Linux system. This
assists the 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.

iSCSI Target

The Linux target (tgt) framework allows a system to serve
block-level SCSI storage to other systems that have a SCSI
initiator. This capability is being initially deployed as a Linux
iSCSI target, serving storage over a network to any iSCSI
initiator.

To set up the iSCSI target, install the scsi-target-utils RPM and
refer to the instructions in:

o /usr/share/doc/scsi-target-utils-<version>/README

o /usr/share/doc/scsi-target-utils-<version>/README.iscsi

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

For more information, refer to man tgtadm.

FireWire

The firewire-sbp2 module is included in this update as a
Technology Preview. This module enables connectivity with FireWire
storage devices and scanners.

At present, FireWire does not support the following:

o IPv4

o pcilynx host controllers

o multi-LUN storage devices

o non-exclusive access to storage devices

In addition, the following issues still exist in this version of
FireWire:

o a memory leak in the SBP2 driver may cause the machine to
become unresponsive.

o a code in this version does not work properly in big-endian
machines. This could lead to unexpected behavior in PowerPC.

Resolved Issues

o A SATA bug that caused SATA-equipped systems to pause during the boot
process and display an error before resuming is now fixed.

o In multi-boot systems, parted now preserves the starting sector of the
first primary partition where Windows Vista(TM) is installed. As such,
when setting up a multi-boot system with both Red Hat Enterprise Linux
5.1 and Windows Vista(TM), the latter is no longer rendered
unbootable.

o rmmod xennet no longer causes domU to crash.

o 4-socket AMD Sun Blade X8400 Server Module systems that do not have
memory configured in node 0 no longer panic during boot.

o conga and luci can now be used to create and configure failover
domains.

o When installing the Cluster Storage group through yum, the transaction
no longer fails.

o During installation, incorrect SELinux contexts are no longer assigned
to /var/log/faillog and /var/log/tallylog.

o Installing Red Hat Enterprise Linux 5.1 using split installation media
(for example, CD or NFSISO) no longer causes an error in the
installation of amanda-server.

o EDAC now reports the correct amount of memory on the latest k8
processors.

o Logging in remotely to a Gnome desktop via gdm no longer causes the
login screen to hang.

o A bug in autofs that prevented multi-mounts from working properly is
now fixed.

o Running tvtime and xawtv with the bttv kernel module no longer causes
the system to freeze.

o Several patches to utrace apply the following fixes:

o fixed a bug that causes a crash in race condition when using
ptrace

o fixed a regression that resulted in erroneous EIO returns from
some PTRACE_PEEKUSR calls

o fixed a regression that prevented some wait4 calls from waking up
when a child exited under certain circumstances

o fixed a regression that sometimes prevented SIGKILL from
terminating a process. This occurred if ptrace was performed on a
process under certain cirtumstances.

o A RealTime Clock (RTC) bug that prevented alarms and periodic RTC
interrupts from working properly is now fixed.

Known Issues

o The first time the Release Notes button is clicked in Anaconda, a
delay occurs while the window renders the Release Notes. During this
delay, a seemingly empty list appears in the window. The rendering
normally completes quickly, so most users may not notice this.

This delay is mostly due to the fact that the package installation
phase is the most CPU-intensive phase of installation.

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 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 Laptops equipped with the Cisco Aironet MPI-350 wireless 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.

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

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 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 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.

This will be resolved in an upcoming BIOS update by HP.

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

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 Removable storage devices (such as CDs and DVDs) do not automatically
mount when you are logged in as root. As such, you will need to
manually mount the device through the graphical file manager.

Alternatively, you can run the following command to mount a device to
/media:

mount /dev/<device name> /media

o The Calgary IOMMU chip is not supported by default in this update. To
enable support for this chip, use the kernel command line option
iommu=calgary.

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 upgrading from Red Hat Enterprise Linux 5 to Red Hat Enterprise
Linux 5.1 via Red Hat Network, yum may not prompt you to import the
redhat-beta key. As such, it is advised that you import the
redhat-beta key manually prior to upgrading. To do this, run the
following command:

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-beta

o When a LUN is deleted on a configured filer, the change is not
reflected on the host. In such cases, lvm commands will hang
indefinitely when dm-multipath is used, as the LUN has now become
stale.

To work around this, delete all device and mpath link entries in
/etc/lvm/.cache specific to the stale LUN.

To find out what these entries are, run the following command:

ls -l /dev/mpath | grep <stale LUN>

For example, if <stale LUN> is 3600d0230003414f30000203a7bc41a00, the
following results may appear:

lrwxrwxrwx 1 root root 7 Aug 2 10:33 /3600d0230003414f30000203a7bc41a00 -> ../dm-4
lrwxrwxrwx 1 root root 7 Aug 2 10:33 /3600d0230003414f30000203a7bc41a00p1 -> ../dm-5

This means that 3600d0230003414f30000203a7bc41a00 is mapped to two
mpath links: dm-4 and dm-5.

As such, the following lines should be deleted from /etc/lvm/.cache:

/dev/dm-4
/dev/dm-5
/dev/mapper/3600d0230003414f30000203a7bc41a00
/dev/mapper/3600d0230003414f30000203a7bc41a00p1
/dev/mpath/3600d0230003414f30000203a7bc41a00
/dev/mpath/3600d0230003414f30000203a7bc41a00p1

o When attempting to create a fully virtualized Windows(TM) guest from a
CD or DVD, the second stage of the guest install might 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 If the sctp module is not added to the kernel, running netstat with
the -A inet or -A inet6 option abnormally terminates with the
following message:

netstat: no support for `AF INET (sctp)' on this system.

To avoid this, install the sctp kernel module.

o 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.

o Current kernels do not assert Data Terminal Ready (DTR) signals before
printing to serial ports during boot time. DTR assertion is required
by some devices; as a result, kernel boot messages are not printed to
serial consoles on such devices.

o Upgrading a host (dom0) system to Red Hat Enterprise Linux 5.1 may
render existing Red Hat Enterprise Linux 4.5 SMP paravirtualized
guests unbootable. This is more likely to occur when the host system
has more than 4GB of RAM.

To work around this, boot each Red Hat Enterprise Linux 4.5 guest in
single CPU mode and upgrade its kernel to the latest version (for Red
Hat Enterprise Linux 4.5.z).

o The AMD 8132 and HP BroadCom HT100 used on some platforms (such as the
HP dc7700) do not support MMCONFIG cycles. If your system uses either
chipset, your PCI configuration should use the legacy PortIO CF8/CFC
mechanism. To configure this, boot the system with the kernel
parameter -pci nommconfig during installation and add pci=nommconf to
GRUB after rebooting.

Further, the AMD 8132 chipset does not support Message Signaled
Interrupts (MSI). If your system uses this chipset, you should also
disable MSI. To do this, use the kernel parameter -pci nomsi during
installation and add pci=nomsi to GRUB after rebooting.

However, if your specific platform is already blacklisted by the
kernel, your system does not require the aforementioned pci kernel
parameters. The following HP platforms are already blacklisted by the
kernel:

o DL585g2

o dc7500

o xw9300

o xw9400

o The Virtual Machine Manager (virt-manager) included in this release
does not allow users to specify additional boot arguments to the
paravirtualized guest installer. This is true even when such arguments
are required to install certain types of paravirtualized guests on
specific types of hardware.

This issue will be addressed in a future release of virt-manager. To
specify arbitrary kernel arguments in installing paravirtualized
guests from the command line, use virt-install.

o With the default dm-multipath configuration, Netapp devices may take
several minutes to complete failback after a previously failed path is
restored. To resolve this problem, add the following Netapp device
configuration to the devices section of the multipath.conf file:

devices {
device {
vendor "NETAPP"
product "LUN"
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_netapp /dev/%n"
features "1 queue_if_no_path"
hardware_handler "0"
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
rr_min_io 128
path_checker directio
}

( amd64 )

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

^[[7]1] This material may be distributed only subject to the terms and
conditions set forth in the Open Publication License, v1.0, available at
[8]http://www.opencontent.org/openpub/.

References

Visible links
1. file:///NotBackedUp/docs-stuff/readmes/RHEL5/RELEASE-NOTES-U1-x86_64-en.html#ftn.id3631995
2. http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/index.html
3. http://libvirt.org/
4. http://www.kerneldrivers.org/RedHatKernelModulePackages
5. http://fedoraproject.org/wiki/StatelessLinuxHOWTO
6. mailto:[email protected]
7. file:///NotBackedUp/docs-stuff/readmes/RHEL5/RELEASE-NOTES-U1-x86_64-en.html#id3631995
8. http://www.opencontent.org/openpub/