Red Hat ENTERPRISE 5.4 RELEASE NOTES Instruction Manual

1
Red Hat Enterprise
Linux 5.4
Release Notes
Release Notes for all architectures.
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Abstract
This document details the Release Notes for Red Hat Enterprise Linux 5.4.
1. Virtualization Updates .............................................................................................................. 2
2. Clustering Updates ................................................................................................................. 3
2.1. Fencing Improvements ................................................................................................. 4
3. Networking Updates ................................................................................................................ 5
4. Filesystems and Storage updates ............................................................................................ 5
5. Desktop Updates .................................................................................................................... 6
5.1. Advanced Linux Sound Architecture .............................................................................. 6
5.2. Graphics Drivers .......................................................................................................... 6
5.3. Laptop Support ............................................................................................................ 7
6. Tools Updates ......................................................................................................................... 7
7. Architecture Specific Support ................................................................................................... 8
7.1. i386 ............................................................................................................................. 8
7.2. x86_64 ........................................................................................................................ 9
7.3. PPC ............................................................................................................................ 9
7.4. s390 ............................................................................................................................ 9
8. Kernel Updates ..................................................................................................................... 11
8.1. General Kernel Feature Support .................................................................................. 11
8.2. General Platform Support ........................................................................................... 13

Release Notes
2
8.3. Driver Updates ........................................................................................................... 13
9. Technology Previews ............................................................................................................. 18
A. Revision History 19
This document contains the Release Notes for the Red Hat Enterprise Linux 5.4 family of products
including:
• Red Hat Enterprise Linux 5 Advanced Platform for x86, AMD64/Intel® 64, Itanium Processor Family,
System p and System z
• Red Hat Enterprise Linux 5 Server for x86, AMD64/Intel® 64, Itanium Processor Family, System p
and System z
• Red Hat Enterprise Linux 5 Desktop for x86 and AMD64/Intel®
The Release Notes provide high level coverage of the improvements and additions that have been
implemented in Red Hat Enterprise Linux 5.4. For detailed documentation on all changes to Red Hat
Enterprise Linux for the 5.4 update, refer to the Technical Notes1
1. Virtualization Updates
Red Hat Enterprise Linux 5.4 now includes full support for the Kernel-based Virtual Machine (KVM)
hypervisor on x86_64 based architectures. KVM is integrated into the Linux kernel, providing a
virtualization platform that takes advantage of the stability, features, and hardware support inherent
in Red Hat Enterprise Linux. Virtualization using the KVM hypervisor is supported on wide variety of
guest operating systems, including:
• Red Hat Enterprise Linux 3
• Red Hat Enterprise Linux 4
• Red Hat Enterprise Linux 5
• Windows XP
• Windows Server 2003
• Windows Server 2008
Important
Xen based virtualization is fully supported. However, Xen-based virtualization requires a
different version of the kernel to function. The KVM hypervisor can only be used with the
regular (non-Xen) kernel.
Warning
While Xen and KVM may be installed on the same system, the default networking
configuration for these are different. Users are strongly recommended to only install one
hypervisor on a system.
1 http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.4/html/Technical_Notes/

Clustering Updates
3
Note
Xen is the default hypervisor that is shipped with Red Hat Enterprise Linux. As such
all configuration defaults are tailored for use with the Xen hypervisor. For details on
configuring a system for KVM, please refer to the Virtualization Guide.
Virtualization using KVM allows both 32-bit and 64-bit versions of guest operating systems to be run
without modification. Paravirtualized disk and network drivers have also been included in Red Hat
Enterprise Linux 5.4 for enhanced I/O performance. All the libvirt based tools (i.e. virsh, virt-
install and virt-manager) have also been updated with added support for KVM.
USB passthrough with the KVM hypervisor is considered to be a Technology Preview for the 5.4
release.
With resolution of various issues such as: save/restore, live migration and core dumps, Xen based 32
bit paravirtualized guests on x86_64 hosts are no longer classed as a Technology Preview, and are
fully supported on Red Hat Enterprise Linux 5.4.
the etherboot package has been added in this update, providing the capability to boot guest virtual
machines using the Preboot eXecution Environment (PXE). This process occurs before the OS
is loaded and sometimes the OS has no knowledge that it was booted through PXE. Support for
etherboot is limited to usage in the KVM context.
The qspice packages have been added to Red Hat Enterprise Linux 5.4 to support the spice protocol
in qemu-kvm based virtual machines. qspice contains both client, server and web browser plugin
components. However, only the qspice server in the qspice-libs package is fully supported.
The qspice client (supplied by the qspice package) and qspice mozilla plugin (supplied by the qspice-
mozilla package) are both included as Technology Previews. The qspice-libs package contains
the server implementation that is used in conjunction with qemu-kvm and as such is fully supported.
However, in Red Hat Enterprise Linux 5.4 there is no libvirt support for the spice protocol; the only
supported use of spice in Red Hat Enterprise Linux 5.4 is through the use of the Red Hat Enterprise
Virtualization product.
Important
The virtio-win component is only available via the Red Hat Network, and is not included on
the physical Supplementary CD for Red Hat Enterprise Linux 5.4. For more information,
see the Red Hat Knowledgebase2.
2. Clustering Updates
Clusters are multiple computers (nodes) working in concert to increase reliability, scalability, and
availability to critical production services.
All updates to clustering in Red Hat Enterprise Linux 5.4 are detailed in the Technical Notes. Further
information on clustering in Red Hat Enterprise Linux is available in the Cluster Suite Overview3 and
the Cluster Administration4 documents.
3 http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Suite_Overview/index.html
4 http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Cluster_Administration/index.html

Release Notes
4
Cluster Suite tools have been upgraded to support automatic hypervisor detection. However, running
the cluster suite in conjunction with KVM hypervisor is considered to be a Technology Preview.
OpenAIS now provides broadcast network communication in addition to multicast. This functionality
is considered Technology Preview for standalone usage of OpenAIS and for usage with the Cluster
Suite. Note, however, that the functionality for configuring OpenAIS to use broadcast is not integrated
into the cluster management tools and must be configured manually.
Note
SELinux in Enforcing mode is not supported with the Cluster Suite; Permissive or
Disabled modes must be used. Using Cluster Suite on bare metal PPC systems is not
supported. Guests running Cluster Suite on VMWare ESX hosts and using fence_vmware
is considered a Technology Preview. Running Cluster Suite in guests on VMWare ESX
hosts that are managed by Virtual Center is not supported.
Mixed architecture clusters using Cluster Suite are not supported. All Nodes in the cluster
must be of the same architecture. For the purposes of Cluster Suite, x86_64, x86 and
ia64 are considered to be the same architecture, so running clusters with combinations of
these architectures is supported.
2.1. Fencing Improvements
Fencing is the disconnection of a node from the cluster's shared storage. Fencing cuts off I/O from
shared storage, thus ensuring data integrity.
In Red Hat Enterprise Linux 5.4, fencing support on Power Systems has been added, as a
Technology Preview, for IBM Logical Partition (LPAR) instances that are managed using the Hardware
Management Console (HMC) (BZ#485700)5. Fencing support has also been added, as a Technology
Preview for Cisco MDS 9124 & Cisco MDS 9134 Multilayer Fabric Switches (BZ#480836).6
The fence_virsh fence agent is provided in this release of Red Hat Enterprise Linux as a
Technology Preview. fence_virsh provides the ability for one guest (running as a domU) to fence
another using the libvirt protocol. However, as fence_virsh is not integrated with cluster-suite it is
not supported as a fence agent in that environment.
The fence_scsi man page has been updated, detailing the following limitations:
The fence_scsi fencing agent requires a minimum of three nodes in the cluster to operate. For
an FC connected SAN devices, these must be physical nodes. SAN devices connected via iSCSI
may use virtual or physical nodes. In addition, fence_scsi cannot be used in conjunction
with qdisk.
Additionally, the following new articles on fencing have been published on the Red Hat Knowledge
Base:
• SCSI Fencing (Persistent Reservations) with Red Hat Enterprise Linux 5 Advanced Platform Cluster
Suite: http://kbase.redhat.com/faq/docs/DOC-17809
• Using fence_vmware with Red Hat Enterprise Linux 5 Advanced Platform Cluster Suite: http://
kbase.redhat.com/faq/docs/DOC-17345
5 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=485700
6 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=480836

Networking Updates
5
3. Networking Updates
With this update, Generic Receive Offload (GRO) support has been implemented in both the kernel
and the userspace application, ethtool.((BZ#499347)7) The GRO system increases the performance
of inbound network connections by reducing the amount of processing done by the Central Processing
Unit (CPU). GRO implements the same technique as the Large Receive Offload (LRO) system, but
can be applied to a wider range of transport layer protocols. GRO support has also been added to a
several network device drivers, including the igb driver for Intel® Gigabit Ethernet Adapters and the
ixgbe driver for Intel 10 Gigabit PCI Express network devices.
The Netfilter framework (the portion of the kernel resposible for network packet filtering) has been
updated with added support for Differentiated Services Code Point (DSCP) values
the bind (Berkeley Internet Name Domain) package provides an implementation of the DNS (Domain
Name System) protocols. Previously, bind did not offer a mechanism to easily distinguish between
requests that will receive authoritative and non-authoritative replies. Consequently, an incorrectly
configured server may have replied to requests that should have been denied. With this update,
bind has been updated, providing the new option allow-query-cache that controls access
to non-authoritative data on a server (for example: cached recursive results and root zone hits).
(BZ#483708)8
4. Filesystems and Storage updates
In the 5.4 update, several significant additions have been made to file systems support. Base Red Hat
Enterprise Linux now includes the Filesystem in Userspace (FUSE) kernel modules and user
space utilities, allowing users to install and run their own FUSE file systems on an unmodified Red Hat
Enterprise Linux kernel (BZ#457975)9. Support for the XFS file system has also been added to the
kernel for future product enablement (BZ#470845)10. The FIEMAP input/output control (ioctl) interface
has been implemented, allowing the physical layout of files to be mapped efficiently. The FIEMAP ioctl
can be used by applications to check for fragmentation of a specific file or to create an optimized copy
of a sparsely allocated file (BZ#296951)11.
Additionally, the Common Internet File System (CIFS) has been updated in the kernel (BZ#465143)12.
The ext4 file system (included in Red Hat Enterprise Linux as a Technology Preview) has also been
updated (BZ#485315)13.
In Red Hat Enterprise Linux 5.4, the use of the Global File System 2 (GFS2) as a single server file
system (i.e. not in a clustered environment) is deprecated. Users of GFS2 that do not need high
availability clustering are encouraged to look at migrating to other file systems like the ext3 or xfs
offerings. The xfs file system is specifically targeted at very large file systems (16 TB and above).
Existing users will continue to be supported.
The required semantics indicate that a process which completes a stat, write, stat, should
see a different mtime (time of last modification) on the file in the results from the second stat call
compared to the mtime in the results from the first stat call. File times in NFS are maintained strictly
by the server, so the file mtime will not be updated until the data has been transmitted to the server
7 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=499347
8 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=483708
9 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=457975
10 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=470845
11 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=296951
12 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=465143
13 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=485315

Release Notes
6
via the WRITE NFS protocol operation. Simply copying data into the pagecache is not sufficient
to cause the mtime to be updated. This is one place where NFS differs from local file systems.
Therefore, an NFS filesystem which is under a heavy write workload may result in stat calls having a
high latency.(BZ#469848)14
The ext4 filesystem Technology Preview has been refreshed with updated userspace tools. Ext4 is an
incremental improvement on the ext3 file system developed by Red Hat and the Linux community.
Note
In previous versions of Red Hat Enterprise Linux utilizing the ext4 Technology Preview,
ext4 filesystems were labeled as ext4dev. With this update, ext4 filesystems are now
tagged as ext4.
With this update, the dmraid logwatch-based email reporting feature has been moved from the
dmraid-events package into the new dmraid-events-logwatch package. Consequently,
systems that use this dmraid feature will need to complete the following manual procedure:
1. ensure the new 'dmraid-events-logwatch' package is installed.
2. un-comment the functional portion of the /etc/cron.d/dmeventd-logwatch crontab file.
(BZ#512833)15
samba3x and ctdb are provided as a Technology Preview on the x86_64 platform. Samba3x package
provides Samba 3.3 and ctdb provide a clustered TDB backend. Running samba3x and ctdb on a set
of cluster nodes with GFS file system will allow the export of a clustered CIFS filesystem.
Important
the samba3x packages conflict with the samba-3.0 packages shipped with Red Hat
Enterprise Linux 5. To use the Technology Preview, it is recommended to perform a fresh
install that does not include the samba-3.0 packages, and then to install the samba3x
packages from the Supplementary media.
5. Desktop Updates
5.1. Advanced Linux Sound Architecture
In Red Hat Enterprise Linux 5.4, the Advanced Linux Sound Architecture (ALSA) has been updated —
providing enhanced support for High Definition Audio (HDA).
5.2. Graphics Drivers
The ati driver for ATI video devices has been updated.
The i810 and intel drivers for Intel integrated display devices have been updated.
The mga driver for Matrox video devices has been updated.
14 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=469848
15 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=512833

Laptop Support
7
The nv driver for nVidia video devices has been updated.
5.3. Laptop Support
Previously, when undocking and docking some laptops with docking stations containing integrated CD/
DVD drives, the drive would no longer be recognized. The system would need to be rebooted for the
drive to be accessible. With this update, the ACPI docking drivers have been updated in the kernel,
resolving this issue. (BZ#485181).16
6. Tools Updates
Important
All the IBM Java components are available online due to a late detection of missing
COPYRIGHT notice. This applies to the Supplementary CD contents for Red Hat
Enterprise Linux 5 on all architectures and releases. For more information, see the Red
Hat Knowledgebase17.
•SystemTap is now fully supported, and has been re-based to the latest upstream version. This
update features improved user-space probing through shared libraries, experimental DWARF
unwinding, and a new <sys/sdt.h> header file which provides dtrace-compatible markers.
This re-base also enhances support for debuginfo-less operations. Typecasting (through the
@cast operator) is now supported, along with kernel tracepoint probing. Several 'kprobe.*'
probe bugs that hampered debuginfo-less operations are also now resolved.
SystemTap also features several documentation improvements. A new '3stap' feature provides
users with useful man pages on most SystemTap probes and functions. The systemtap-
testsuite package also features a larger library of sample scripts.
For more information about the SystemTap re-base, please refer to the SystemTap section Package
Updates chapter of the Technical Notes.
• Systemtap tracepoints are placed in important sections of the kernel, allowing system administrators
to analyze the performance of, and debug portions of code. In Red Hat Enterprise Linux 5.4,
tracepoints have been added to the following sections of the kernel subsystem as a Technology
Preview:
• Memory Management (mm) (BZ#493444)18
• Block Device I/O (blktrace)(Bugzilla #493454)19
• Network File System (NFS) (BZ#499008)20
• Page Cache and Networking stacks (BZ#475719)21
• Scheduler (BZ#497414)22
• The Gnu Compiler Collection version 4.4 (GCC4.4) is now included in this release as a Technology
Preview. This collection of compilers include C, C++, and Fortran compilers along with support
libraries.
16 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=485181

Release Notes
8
•glibc new MALLOC behaviour: The upstream glibc has been changed recently to enable
higher scalability across many sockets and cores. This is done by assigning threads their
own memory pools and by avoiding locking in some situations. The amount of additional
memory used for the memory pools (if any) can be controlled using the environment variables
MALLOC_ARENA_TEST and MALLOC_ARENA_MAX.
MALLOC_ARENA_TEST specifies that a test for the number of cores is performed once the number
of memory pools reaches this value. MALLOC_ARENA_MAX sets the maximum number of memory
pools used, regardless of the number of cores.
The glibc in the RHEL 5.4 release has this functionality integrated as a Technology Preview
of the upstream malloc. To enable the per-thread memory pools the environment variable
MALLOC_PER_THREAD needs to be set in the environment. This environment variable will
become obsolete when this new malloc behaviour becomes default in future releases. Users
experiencing contention for the malloc resources could try enabling this option.
7. Architecture Specific Support
7.1. i386
• In a virtual environment, timekeeping for Red Hat Enterprise Linux 64-bit kernels can be
problematic, since time is kept by counting timer interrupts. De- and re-scheduling the virtual
machine can cause a delay in these interrupts, resulting in a timekeeping discrepancy. This kernel
release reconfigures the timekeeping algorithm to keep time based on a time-elapsed counter.
(Bugzilla #46357323)
• It was found that, if their stacks exceed the combined size of ~4GB, 64-bit threaded applications
slowed down drastically in pthread_create(). This is because glibc uses MAP_32BIT to
allocate those stacks. As the use of MAP_32BIT is a legacy implementation, this update adds a new
flag (MAP_STACK mmap) to the kernel to avoid constraining 64-bit applications. (Bugzilla #45932124)
• The update includes a feature bit that encourages TSCs to keep running in deep-C states. This bit
NONSTOP_TSC acts in conjunction with CONSTANT_TSC. CONSTANT_TSC indicates that the TSC
runs at constant frequency irrespective of P/T- states, and NONSTOP_TSC indicates that TSC does
not stop in deep C-states. (Bugzilla #47409125)
• This update includes a patch to include asm-x86_64 headers in kernel-devel packages built on or
for i386, i486, i586 and i686 architectures. (Bugzilla #49177526)
• This update includes a fix to ensure that specifying memmap=X$Y as a boot parameter on i386
architectures yields a new BIOS map. (Bugzilla #46450027)
• This update adds a patch to correct a problem with the Non-Maskable Interrupt (NMI) that appeared
in previous kernel releases. The problem appeared to affect various Intel processors and caused the
system to report the NMI watchdog was 'stuck'. New parameters in the NMI code correct this issue.
(Bugzilla #50089228)
• This release re-introduces PCI Domain support for HP xw9400 and xw9300 systems. (Bugzilla
#47489129)
• Functionality has been corrected to export module powernow-k8 parameters to /sys/modules. This
information was previously not exported.(Bugzilla #49201030)

x86_64
9
7.2. x86_64
• An optimization error was found in linux-2.6-misc-utrace-update.patch. When running 32-
bit processes on a 64-bit machine systems didn't return ENOSYS on missing (out of table range)
system calls. This kernel release includes a patch to correct this. (Bugzilla #48168231)
• Some cluster systems were found to boot with an unstable time source. It was determined that this
was a result of kernel code not checking for a free performance counter (PERFCTR) when calibrating
the TSC (Time Stamp Clock) during the boot process. This resulted, in a small percentage of cases,
in the system defaulting to a busy PERFCTR and getting unreliable calibrations.
A fix was implemented to correct this by ensuring the system checked for a free PERFCTR before
defaulting (Bugzilla #46778232). This fix, however, cannot satisfy all possible contingencies as it is
possible that all PERFCTRs will be busy when required for TSC calibration. Another patch has been
included to initiate a kernel panic in the unlikely event (fewer than 1% of cases) that this scenario
occurs. (Bugzilla #47252333).
7.3. PPC
• This kernel release includes various patches to update the spufs (Synergistic Processing Units file
system) for Cell processors. (Bugzilla #47562034)
• An issue was identified wherein /proc/cpuinfo would list logical PVR Power7 processor
architecture as "unknown" when show_cpuinfo() was run. This update adds a patch to have
show_cpuinfo() identify Power7 architectures as Power6. (Bugzilla #48664935)
• This update includes several patches that are required to add/improve MSI-X (Message Signaled
Interrupts) support on machines using System P processors. (Bugzilla #49258036)
• A patch has been added to this release to enable the functionality of the previously problematic
power button on Cell Blades machines. (Bugzilla #47565837)
7.4. s390
Red Hat Enterprise Linux introduces a wide range of new features for IBM System z machines, most
notably:
• Utilizing Named Saved Segments (NSS), the z/VM hypervisor makes operating system code in
shared real memory pages available to z/VM guest virtual machines. With this update, multiple Red
Hat Enterprise Linux guest operating systems on the z/VM can boot from the NSS and be run from a
single copy of the Linux kernel in memory. (BZ#474646)38
• Device driver support has been added in this update for the new IBM System z PCI cryptography
accelerators, utilizing the same interfaces as prior versions. (BZ#488496)39
• Red Hat Enterprise Linux 5.4 adds support for processor degradation, which allows processor
speed to be reduced in some circumstances (i.e. system overheating). (BZ#474664)40 This new
feature allows automation software to observe the machine state and act based on defined policies.
Note
Processor degradation is supported on z990, z890 and later systems and is observed
through SCLP system service event type 4 event qualifier 3. STSI will report the

Release Notes
10
new capacity of the processor in the file: /sys/devices/system/cpu/cpuN/
capability.
• Control Program Identification (CPI) descriptive data is used to identify individual systems on the
Hardware Management Console (HMC). With this update, CPI data can now be associated with a
Red Hat Enterprise Linux instance. (BZ#475820)41
For more information on CPI refer to the Device Drivers, Features, and Commands document42
• Fibre Channel Protocol (FCP) performance data can now be measured on Red Hat Enterprise Linux
instances on the IBM System z platform. (BZ#475334)43 Metrics that are collected and reported on
include:
• Performance relevant data on stack components such as Linux devices, Small Computer System
Interface (SCSI) Logical Unit Numbers (LUNs) and Host Bus Adapter (HBA) storage controller
information.
• Per stack component: current values of relevant measurements as throughput, utilization and
other applicable measurements.
• Statistical aggregations (minimum, maximum, averages and histogram) of data associated with I/
O requests including size, latency per component and totals.
• Support has been added to the kernel to issue EMC Symmetrix Control I/O. This update provides
the ability to manage EMC Symmetrix storage arrays with Red Hat Enterprise Linux on the IBM
System z platform. (BZ#461288)44
• A new feature has been implemented in the kernel to perform an Initial Program Load (IPL)
on a Red Hat Enterprise Linux virtual machine immediately following a kernel panic and
dump.(BZ#474688)45
• Hardware that supports the configuration topology facility passes the system CPU topology
information to the scheduler, allowing it to make load balancing decisions. On machines where I/O
interrupts are unevenly distributed, CPUs that are grouped together and get more I/O interrupts than
others will tend to have a higher average load, creating performance issues in some cases.
Previously, CPU topology support was enabled by default. With this update, CPU topology support
is disabled by default, and the kernel parameter "topology=on" has been added to allow this feature
to be enabled. (BZ#475797)46
• New kernel options can now be added using the IPL command without modifying the content of the
CMS parmfile, allowing for temporary overwriting of kernel options that are already provided by the
parmfile. The entire boot command line can be replaced with the VM parameter string, bypassing
any kernel options from the parmfile. Furthermore, customers can create new Linux Named Saved
Systems (NSS) on the CP/CMS command line. (BZ#475530)47
• The qeth driver has been updated with HiperSockets Layer3 support for IPv6. (BZ#475572)48
For further details on this feature, refer to the "qeth device driver for OSA-Express (QDIO) and
HiperSockets" chapter in IBM's "Device Drivers, Features, and Commands" book located at: http://
www.ibm.com/developerworks/linux/linux390/october2005_documentation.html
• Starting with z9 HiperSocket firmware returns the version string in a different format. This change
resulted in missing mcl_level information in the qeth status message issued during online setting

Kernel Updates
11
of the device. The updated qeth driver now correctly reads the new version string format of
HiperSockets, allowing for a standardization of output format. (BZ#479881)49
• In Red Hat Enterprise Linux 5.4, the s390utils package has been rebased to version 1.8.1. For
a full list of features that this rebase provides, please refer to the Package Updates section of the
Technical Notes50. (BZ#477189)51
• In the kernel, a sysfs interface has been implemented to associate actions to shutdown triggers.
For more details on this feature, refer to the "Shutdown actions" chapter in IBM's "Device Drivers,
Features, and Commands" book located at: http://www.ibm.com/developerworks/linux/linux390/
development_documentation.html
8. Kernel Updates
8.1. General Kernel Feature Support
• Asymmetric Logical Unit Access (ALUA) support in device-mapper-multipath has been updated,
adding explicit ALUA support for Clariion storage. Earlier versions of Red Hat Enterprise Linux 5
added support for implicit ALUA (i.e. the operating system is not aware of which storage device
paths have optimized performance and which have non-optimized performance). If the operating
system consistently sends I/O on a non-optimized path, then the storage device may transparently
make that path optimized, improving performance and causing idle paths to become non-optimized.
Red Hat Enterprise Linux 5.4 introduces explicit ALUA support for Clariion storage (i.e. the operating
system exchanges information with the storage device and is able to select the paths that have
optimized performance). (BZ#482737)52
• Previously, support for raw devices in the upstream kernel was deprecated. However, this support
has been returned to the kernel. Consequently, in Red Hat Enterprise Linux 5.4, support for raw
devices has also been returned. Additionally, the initscripts packages have been updated, adding
the previously dropped functionality of raw devices.(BZ#472891)53
• KVM guest-smp tlb flushing without mmu-notifiers could corrupt memory as a KVM may add
pages to the kernel freelist while another vcpu may still be writing to them through guest mode. This
update adds mmu-notifier support to the kernel and also corrects a bug found in an earlier patch
wherein mm_struct was grown by existing drivers and caused a failed kABI check. This bug has
been corrected by using an index that resides in an unused padding hole to avoid expanding the
structure size.(Bugzilla #48571854)
• Pointer and signed arithmetic overflow wrapping has not previously been defined in the Linux kernel.
This could cause GCC (GNU C Compiler) to assume that wrapping does not occur and attempt
to optimize the arithmetic that the kernel may require for overflow testing. This update adds the -
fwrapv variable to GCC CFLAGS in order to define wrapping behavior.(Bugzilla #49126655)
• An issue of contention between processes vying for the same memory space in high end
systems was recently identified by TPC-C (Transaction Processing Council) benchmarking. This
update includes fast-gup patches which use direct IO and provide a significant (up to 9-10%)
performance improvement. This update has been tested thoroughly and is used in the 5.4 kernel to
improve scalability. For further information, see this article56. (Bugzilla #47491357)
• A new tunable parameter has been added to this kernel, allowing system administrators to change
the maximum number of modified pages kupdate writes to disk per iteration each time it runs.

Release Notes
12
This new tunable /proc/sys/vm/max_writeback_pages defaults to 1024 or 4MB so that a
maximum of 1024 pages get written out by each iteration of kupdate. (Bugzilla #47907958).
• A new option (CONFIG_TASK_IO_ACCOUNTING=y) has been added to kernel to assist in
monitoring IO statistics per process. This assists with troubleshooting in a production environment.
(Bugzilla #46163659)
• In previous kernels, back-up processes were deteriorating DB2 server responsiveness. This was
caused by /proc/sys/vm/dirty_ratio preventing processes writing to pagecache memory
when more than half of the unmapped pagecache memory was dirty (even if dirty_ratio was
set to 100%). A change made in this kernel update overrides this limiting behavior. Now, when the
dirty_ratio is set to 100%, the system will no longer limit writing to pagecache memory. (Bugzilla
#29529160)
• The rd_blocksize option found in the previous kernel's ramdisk driver was causing data
corruption when using large ramdisks under a reasonable system load. This update removes the
unnecessary option and resolves the data corruption issues. (Bugzilla #48066361)
• The function getrusage is used to examine the resource usage of a process. It is useful in
diagnosing problems and gathering data on resource usage. In instances where a process
interrogated by getrusage was spawning child process threads, however, the results would be in
incorrect as getrusage would examine only the parent process and not interrogate its children.
This update implements rusadge_thread to allow for accurate resource usage results in these
instances. (Bugzilla #45106362)
• The header /usr/include/linux/futex.h would previously interfere with compiling C source
code files, resulting in an error. This update includes a patch which corrects problematic kernel only
definitions and resolves the compiling error. (Bugzilla #47579063)
• In previous kernels the kernel version was not identified in panic or oops output messages. This
update adds the kernel version details to oops and panic output. (Bugzilla #48440364)
• During release 2.6.18, the kernel was configured to provide kernel-headers for the package glibc.
That process caused various files to be improperly marked for inclusion. The serial_reg.h
file was incorrectly marked and not included in the kernel_headers rpm. This, in turn, caused
problems with building other rpms. This update adds the serial_reg.h file and corrects the
problem. (Bugzilla #46353865)
• In some circumstances upcrund, the process manager in the HP Unified Parallel C (UPC)
product, returned an ESRCH result and failed when calling setpgid() for a child process forked by
a sub-thread. This update includes a patch to fix for this problem. (Bugzilla #47243366)
• Functionality has been added to sysrq-t to display backtrace information about running
processes. This will assist in debugging hung systems. (Bugzilla #45658867)
8.1.1. Debugging
In Red Hat Enterprise Linux 5.4, debugging the kernel has been improved with added features for
generating core dumps. Core dumps (memory snapshots) are useful for debugging system and
kernel crashes. With this update, it is now possible to perform a core dump on systems that utilize
hugepages.(BZ#470411)68 Additionally, kernel panic messages can now be extracted from a core
dump file (vmcore) using the makedumpfile command. (BZ#485308)69
68 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=470411

General Platform Support
13
8.1.2. Security
• This update increases the maximum length of the kernel key field from the arbitrary 32 character
length set in previous kernels to 255 characters. (Bugzilla #47514570)
• This kernel update addresses the security concern arising from non-root users being able to create
device nodes on filesystems exported using NFSD (Network File System daemon). This update
returns the CAP_MKNOD and CAP_LINUX_IMMUTABLE) capabilities to the user with the FSUID of 0
in the file system mask. (Bugzilla #49727271 and Bugzilla #49907672)
• In keeping with Federal Information Processing Standardization 140 (FIPS140) certification
requirements, this update includes:
• Self-testing for; ansi_cprng (Bugzilla #49789173), ctr(aes) mode (Bugzilla #49788874), Hmac-
sha512 (Bugzilla #49946375), rfc4309(ccm(aes)). (Bugzilla #47238676), .
• Code to produce a signature file that GRUB performs a checksum against during the boot
process. (Bugzilla #44463277)
• Code to change the DSA key from 512 bit to 1024 bit for module signing. (Bugzilla #41324178)
8.2. General Platform Support
Throttling State (T-State) notification support has been added to the Advanced Configuration
and Power Interface (ACPI) implementation in the kernel. Adding T-State notification enhances
the use of Intel® Intelligent Power Node Manager technology for power management in data
centers.(BZ#487567).79
8.3. Driver Updates
8.3.1. Open Fabrics Enterprise Distribution (OFED) Drivers
The OpenFabrics Alliance Enterprise Distribution (OFED) is a collection of Infiniband and iWARP
hardware diagnostic utilities, the Infiniband fabric management daemon, Infiniband/iWARP kernel
module loader, and libraries and development packages for writing applications that use Remote
Direct Memory Access (RDMA) technology. Red Hat Enterprise Linux uses the OFED software stack
as its complete stack for Infiniband/iWARP/RDMA hardware support.
In Red Hat Enterprise Linux 5.4, the following portions of OFED have been updated to the upstream
version 1.4.1-rc3
• Remote Direct Memory Access (RDMA) headers (BZ#476301)80
• Reliable Datagram Sockets (RDS) protocol (BZ#47706581, BZ#506907)82
• Sockets Direct Protocol (SDP) (BZ#476301)83
• SCSI RDMA Protocol (SRP) (BZ#476301)84
• IP over InfiniBand (IPoIB) (BZ#43477985, BZ#46608686, BZ#50690787)
69 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=485308
79 https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=487567

Release Notes
14
Additionally, the following OFED drivers have been updated to the upstream version 1.4.1-rc3:
• The cxgb3 and iw_cxgb3 drivers for the Chelsio T3 Family of network devices (BZ#476301, 88
BZ#504906)89
• The driver for mthca-based InfiniBand HCA (Host Channel Adapter) (BZ#476301, 90 BZ#506097)91
• qlgc_vnic driver (BZ#476301)92
Note
Red Hat closely tracks the upstream OFED code base in order to provide a maximal level
of enablement for this still evolving technology. As a consequence, Red Hat can only
preserve API/ABI compatibility across minor releases to the degree that the upstream
project does. This is an exception from the general practice in the development of Red Hat
Enterprise Linux.
8.3.2. General Driver Updates
• The i5400 driver for Intel 5400 class Memory Controllers has been updated with added support for
Error Detection And Correction (EDAC). (BZ#462895)93
• the i2c driver for the iic-bus interface has been updated, adding support for the AMD SB800 Family
of products.
• The i2c-piix4 driver has been updated with support for the Broadcom HT1100 chipset.
(BZ#474240)94
• The hpilo driver has been updated.(BZ#488964)95.
• The dm9601 for Davicom Ethernet Adaptors has been updated.
8.3.3. Network Driver Updates
• Red Hat is no longer able to responsibly support the ipw3945 wireless laptop network driver to
the full levels of service, as the upstream company responsible for that driver has suspended
maintenance efforts on the driver.
Red Hat, following the guidance of the company responsible for the driver has migrated over to the
iwl3945 driver (first introduced in Red Hat Enterprise Linux 5.3). Ongoing maintenance of driver
issues associated with the 3945 hardware will be provided on the iwl3945 driver. All fresh/full
installations of Red Hat Enterprise Linux 5.4 on systems with 3945 hardware will install the iwl3945
driver.
Red Hat continues to provide the ipw3945 driver in Red Hat Enterprise Linux 5.4 as a migration
convenience. It is recommended that customers transition to the iwl3945 driver. Refer to the
Red Hat Knowledgebase96 for details on how to transition if you are doing an update install from a
system that had its full installation prior to Red Hat Enterprise Linux 5.4.
Customers who report issues with the ipw3945 driver may be referred to migrate to the iwl3945
driver for resolution. For example, there are known issues connecting to VPN concentrators present
in the ipw3945 driver which are resolved in the iwl3945 driver.

Driver Updates
15
Note
the use of the iwl3945 driver requires installing the iwl3945-firmware package from
the supplementary RHN channel. Package version 15.28.2.8-2 or later is required. (ie
iwl3945-firmware-15.28.2.8-2 or later)
Additionally, the device name, for example as it appears in the output of the
`ifconfig` command appears as eth0 (or eth1) when using the ipw3945 driver,
when using the iwl3945 driver it is identified as wlan0.
• the bonding driver has been updated to the latest upstream version. This update, however has
introduced symbol/ipv6 module dependency capabilities. Therefore, if IPv6 has been previously
disabled (by inserting the install ipv6 /bin/false line in the /etc/modprobe.conf file)
an upgrade to the bonding driver in 5.4 will result in the bonding kernel module failing to load. The
install ipv6 /bin/false line needs to be replaced with options ipv6 "disable=1 for
the module to load properly.
• The drivers in the kernel for Intel® I/O Acceleration Technology (Intel® I/OAT) have been updated to
version 2.6.24.(BZ#436048)97.
• the igb driver for Intel® Gigabit Ethernet Adapters has been updated to version 1.3.16-k2. This
update also enables GRO support for the igb driver. (BZ#484102, 98 BZ#474881, 99BZ#499347).100
• The igbvf driver has been updated, providing Virtual Function support for Intel 82576 Gigabit
Ethernet Controllers. (BZ#480524)101
• the ixgbe driver for Intel 10 Gigabit PBetaCI Express network devices has been updated to
version 2.0.8-k2. This update also enables GRO support for the ixgbe driver. (BZ#472547,
102BZ#499347).103
• The bnx2 driver for Broadcom NetXtreme II network devices has been updated to version 1.9.3
(BZ#475567104 BZ#476897105 BZ#489519)106
• The tg3 driver for Broadcom Tigon3 ethernet devices has been updated to version 3.96.
(BZ#481715, 107 BZ#469772).108 This driver update adds support for 5785F and 50610M devices.
(BZ#506205)109
• The cnic driver has been added, providing Internet Small Computer System Interface (iSCSI)
support for bnx2 network devices. (BZ#441979)110.
• The bnx2x driver for Broadcom Everest network devices has been updated to version
1.48.105.(BZ#475481)111.
• The bnx2i driver has been added, providing iSCSI support for bnx2x network devices.
(BZ#441979)112.
• The cxgb3 driver for the Chelsio T3 Family of network devices has been updated, enabling
iSCSI TCP Offload Engines (TOE) and Generic Receive Offload (GRO) support. (BZ#439518113,
BZ#499347)114
• The forcedeth ethernet driver for NVIDIA nForce devices has been updated to version 0.62.
(BZ#479740).115

Release Notes
16
• The sky2 driver for ethernet controllers using the Marvell Yukon 2 chipset has been updated.
(BZ#484712).116
• The enic driver for Cisco 10G ethernet devices has been updated to version 1.0.0.933.
(BZ#484824)117
• The e1000e driver for Intel PRO/1000 ethernet devices has been updated to the upstream version
1.0.2-k2. (BZ#480241)118
• The be2net driver for Emulex Tiger Shark converged network adapters has been added as a
Technology Preview.
8.3.4. Storage Driver Updates
• The bnx2 driver now supports iSCSI. The bnx2i driver will access the bnx2 driver through the
cnic module to provide iSCSI offload support. To manage bnx2i, use the iscsi-initiator-
utils package. For instructions on bnx2i configuration, please refer to section 5.1.2 of the /
usr/share/docs/iscsi-initiator-utils-<version>/README file. (BZ#441979119 and
BZ#441979120)
Note that the bnx2i version included in this release does not support IPv6.
• The md driver has been updated to provide support for bitmap merging. This feature eliminates the
need for full resync when performing data replication. (BZ#481226121)
• The scsi layer in this release features the following updates:
• The scsi driver now includes the upstream scsi_dh_alua module. This adds explicit
asymmetric logical unit access (ALUA) support with this release. To utilize the scsi_dh_alua
module when using dm-multipath, specify alua as the hardware_handler type in
multipah.conf. (BZ#482737122)
Note that for EMC Clariion devices, using only scsi_dh_alua or dm-emc alone is supported.
Using both scsi_dh_alua and dm-emc is not supported.
• The rdac_dev_list structure now includes md3000 and md3000i entries. This allows users to
benefit from the advantages provided by the iscsi_dh_rdac module. (BZ#487293123)
• A bug that caused iSCSI iBFT installations to panic during disk formatting is now fixed.
(BZ#436791124)
• A bug in the iscsi_r2t_rsp struct that caused kernel panics during iSCSI failovers in some
multipathed environments is now fixed. (BZ#484455125)
• The cxgb3 driver has been updated to apply several upstream fixes and provide support for iSCSI
TOE devices. (BZ#439518126)
Note that the cxgb3i version included in this release does not support IPv6.
• This release includes the new mpt2sas driver. This driver supports the SAS-2 family of adapters
from LSI Logic. SAS-2 increases the maximum data transfer rate from 3Gb/s to 6Gb/s.
The mpt2sas driver is located in the drivers/scsi/mpt2sas directory, as opposed to the older
mpt drivers that are located in drivers/message/fusion directory. (BZ#475665127)

Driver Updates
17
• The aacraid driver has now been updated to version 1.1.5-2461. This update applies several
upstream fixes for bugs affecting queued scans, controller boot problems, and other issues.
(BZ#475559128)
• The aic7xxx driver now features an increased maximum I/O size. This allows supported devices
(such as SCSI tape devices) to perform writes with larger buffers.
• The cciss driver has been updated to apply upstream fixes for bugs affecting memory BAR
discovery, the rebuild_lun_table and the MSA2012 scan thread. This update also applies
several configuration changes to cciss.
• The fnic driver has been updated to version 1.0.0.1039. This applies several upstream bug fixes,
updates the libfc and fcoe modules, and adds a new module parameter that controls debug
logging at runtime. (BZ#484438129)
• The ipr driver now supports MSI-X interrupts. (BZ#475717130)
• The lpfc driver has been updated to version 8.2.0.48. This enables hardware support for upcoming
OEM programs. In addition, this update also applies the following bug fixes (among others):
(BZ#476738131 and BZ#509010132)
• Virtualized fibre-channel switches are now supported.
• Polling for error attention interrupts are now available.
• A bug that caused memory leaks in vport create and delete loop is now resolved.
With this update, the lpfc driver now also supports HBAnyware 4.1 and OneConnect UCNA.
(BZ#498524133)
• The MPT fusion driver is now updated to version 3.04.07rh v2. This applies several bug fixes,
including: (BZ#475455134)
• An MPT fusion driver bug that prevented the system from booting with the PAE kernel is now
fixed.
• Controllers are now set to READY_STATE when the driver unloads.
• The mptsas driver now issues TUR (Test Unit Ready) and Report LUN commands before
adding a device to the transport layer.
In addition, a patch that unexpectedly caused mptctl_ioctl() to issue numerous yet benign
kernel error messages is now reverted. With this release, mptctl_ioctl() no longer issues these
kernel error messages.
• The megaraid_sas driver is now updated to version 4.08-RH1. This update applies the following
upstream enhancements and fixes (among others):(BZ#475574135)
• This upate adds a polling mode to the driver.
• A bug affecting supported tape drives is now fixed. With this release, the pthru timeout value is
now set to the O/S layer timeout value for commands sent to tape drives.

Release Notes
18
• The mvsas driver is now updated to version 0.5.4. This applies several fixes and enhancements
from upstream, and adds support for Marvell RAID bus controllers MV64460, MV64461, and
MV64462. (BZ#485126136)
• The qla2xxx driver has been updated to version 8.03.00.10.05.04-k, and now supports Fibre
Channel over Convergence Enhanced Ethernet adapters. With this release, qla2xxx also applies
several bug fixes from upstream, including: (BZ#471900137, BZ#480204138, BZ#495092139, and
BZ#495094140)
• Discrepancies detected during OVERRUN handling on 4GB and 8GB adapters are now corrected.
• All vports are now alerted of any asynchronous events.
• A bug that caused kernel panics with the QLogic 2472 card is now fixed.
• The stop_firmware command is no longer retried if the first attempt results in a times out.
• The sector mask value is no longer based on the fixed optrom size.
• A bug that caused frequent path failures during I/O on multipathed devices is now fixed.
(BZ#244967141)
• The driver source code is now kABI-compliant.
•dcbx pointers are now set to NULL after freeing memory.
In addition to these updates, the qla24xx and qla25xx firmwares included in the qla2xxx driver
are now updated to version 4.04.09.
• The qla4xxx driver now features improved driver fault recovery. This update fixes a bug in the
driver that prevented adapter recovery if there were outstanding commands detected on the host
adapter. (BZ#497478142)
• This release includes the new qlge driver. This driver adds ethernet support for QLogic FCoE 10GB
adapters. (BZ#479288143)
9. Technology Previews
Technology Preview features are currently not supported under Red Hat Enterprise Linux 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.
The following Technology Previews are new or enhanced in Red Hat Enterprise Linux 5.4. For detailed
information on the Technology Previews in Red Hat Enterprise Linux 5.4, refer to the Technology
Previews section of the 5.4 Technical Notes located at http://www.redhat.com/docs/manuals/
enterprise/
• New Emulex Tiger Shark converged network adapter driver. Refer to Section 8.3.3, “Network Driver
Updates” for more information.
• New Systemtap Tracepoints. Refer to Section 8.1.1, “Debugging” for more information.
• New Gnu Compiler Collection version 4.4. Refer to Section 6, “Tools Updates” for more information.

Revision History
19
• Updated ext4 support. Refer to Section 4, “Filesystems and Storage updates” for more information.
• glibc new MALLOC behaviour. Refer to Section 6, “Tools Updates” for more information.
• samba3x and ctdb on the x86_64 platform. Refer to Section 4, “Filesystems and Storage updates”
for more information.
• Clustering with KVM hypervisor. Refer to Section 2, “Clustering Updates” for more information.
• The fence_virsh fence agent is provided in this release of Red Hat Enterprise Linux as a
Technology Preview. Refer to Section 2.1, “Fencing Improvements” for more information.
• Stream Control Transmission Protocol (SCTP) support for the Cluster Suite and the redundant
ring configuration of clusters are considered Technology Previews in Red Hat Enterprise Linux 5.4.
(BZ#457956)144
• USB passthough with the KVM hypervisor is considered to be a Technology Preview for the 5.4
release.
• In Red Hat Enterprise Linux 5.4, Logical Partition (LPAR) support for the cluster-suite is considered
a Technology Preview. (BZ#480662145, BZ#498083)146
• The xorg-x11-qxl-drv X11 video driver for the qemu QXL video accelerator has been added to
5.4 as a Technology Preview. (BZ#489806)147
A. Revision History
Revision 1.0 Wed Sep 02 2009 Ryan Lerch [email protected]
Initial version of the online version of the Red Hat Enterprise Linux 5.4 Release Notes

20