The following topics are covered in this document:

  • Installation-Related Notes

  • Feature Updates

  • Driver Updates

  • Kernel-Related Updates

  • Virtualization

  • Technology Previews

  • Resolved Issues

  • Known Issues

Some updates on Red Hat Enterprise Linux 5.2 may not appear in this version of the Release Notes. An updated version may also be available at the following URL:

Installation-Related Notes

This section includes information specific to Anaconda and the installation of Red Hat Enterprise Linux 5.2.

To upgrade an already-installed Red Hat Enterprise Linux 5, you can use Red Hat Network to update those packages that have changed. Alternatively, you can also use Anaconda to perform a fresh installation of Red Hat Enterprise Linux 5.2 or to upgrade an already-installed Red Hat Enterprise Linux 5.

Note that upgrading from beta releases to GA releases is not supported. Further, Red Hat does not support in-place upgrades between major versions of Red Hat Enterprise Linux. Although Anaconda provides an option that allows an upgrade from earlier major versions of Red Hat Enterprise Linux (such as Enterprise Linux 4 to Enterprise Linux 5), there is no guarantee that the upgrade will result in a fully functional configuration. In-place upgrades across major releases do not preserve all system settings, services, and custom configurations. For this reason, Red Hat strongly recommends that you perform a fresh installation rather than a system upgrade between major versions.

  • When installing from CD-ROM or DVD-ROM on a system with an iBFT-configured network device, Anaconda will not include any iBFT-configured storage devices unless networking is configured. To enable networking for the installation, use the command linux updates=http://[any] at the installation boot prompt. Note that [any] can be replaced with any URL.

    If your system requires a static IP configuration, use the command linux updates=http://[any] ip=[IP address] netmask=[netmask] dns=[dns].

  • 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 5.2 is installed.

  • When installing Red Hat Enterprise Linux 5.2 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 5.2 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.

  • If you are using the Virtualized kernel when upgrading from Red Hat Enterprise Linux 5 to 5.2, you must reboot after completing the upgrade. You should then boot the system using the updated Virtualized kernel.

    The hypervisors of Red Hat Enterprise Linux 5 and 5.2 are not ABI-compatible. If you do not boot the system after upgrading using the updated Virtualized kernel, the upgraded Virtualization RPMs will not match the running kernel.

  • When upgrading to Red Hat Enterprise Linux 5.1 or later from Red Hat Enterprise Linux 4.6, gcc4 may cause the upgrade to fail. As such, you should manually remove the gcc4 package before upgrading.

  • The firstboot language plugin has been removed, as this plugin does not properly and completely reconfigure the system when a new language is selected.

  • The use of Challenge Handshake Authentication Protocol (CHAP) during installation is not supported. As such, CHAP should only be enabled after installation.

    If your system boots through an iFBT device, configure CHAP in the iFBT BIOS/firmware setup screen. Your CHAP settings will then be used in the next boot.

    If your system boots through PXE iSCSI, configure CHAP through iscsiadm. After configuring, use mkinitrd to ensure that your CHAP settings are used in the next boot.

Feature Updates


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.

Systemtap is now fully supported. For more information about Systemtap, refer to


Internet storage name service for Linux (isns-utils) is now supported. This allows you to register iSCSI and iFCP storage devices on the network. isns-utils allows dynamic discovery of available storage targets through storage initiators.

isns-utils provides intelligent storage discovery and management services comparable to those found in fibre-channel networks. This allows an IP network to function in a similar capacity as a storage area network.

With its ability to emulate fibre-channel fabric services, isns-utils allows seamless integration of IP and fibre-channel networks. In addition, isns-utils also provides the utilities for managing both iSCSI and fibre-channel devices within the network.

For more information about the specifications of isns-utils in this release, refer to For usage instructions, refer to /usr/share/docs/isns-utils-[version]/README and /usr/share/docs/isns-utils-[version]/README.redhat.setup.


rsyslog is an enhanced multi-threaded syslogd daemon that supports the following (among others):

  • MySQL

  • syslog/tcp

  • RFC 3195

  • permitted sender lists

  • filtering on any message part

  • more granular output format control

rsyslog is compatible with the stock sysklogd, and can be used as a replacement in most cases. Its advanced features make it suitable for enterprise-class, encrypted syslog relay chains; at the same time, its user-friendly interface is designed to make setup easy for the novice user.

For more information about rsyslog, refer to


OpenSwan is a free implementation of Internet Protocol Security (IPSEC) and IKE for Linux. IPSEC uses strong cryptography to provide authentication and encryption services. These services allow you to build secure tunnels through untrusted networks. Everything passing through the untrusted network is encrypted by the IPSEC gateway machine and decrypted by the gateway at the other end of the tunnel. The resulting tunnel is a virtual private network (VPN).

This release of OpenSwan also contains an IKE2 daemon that conforms to IETF RFCs. For more information about OpenSwan, refer to


The Evolution update for this release now features the following enhancements (among others):

  • Bogofilter compatibility for filtering junk mail.

  • An option to receive pop-up notifications for new mail.

  • Improved performance for downloading messages from a Microsoft Exchange™ server.

  • A setup assistant to guide you through the process of backing up and restoring data/settings.

Password Hashing Using SHA-256/SHA-512

Password hashing using the SHA-256 and SHA-512 hash functions is now supported.

To switch to SHA-256 or SHA-512 on an installed system, run authconfig --passalgo=sha256 --update or authconfig --passalgo=sha512 --update. To configure the hashing method through a GUI, use authconfig-gtk. Existing user accounts will not be affected until their passwords are changed.

For newly installed systems, using SHA-256 or SHA-512 can be configured only for kickstart installations. To do so, use the --passalgo=sha256 or --passalgo=sha512 options of the kickstart command auth; also, remove the --enablemd5 option if present.

If your installation does not use kickstart, use authconfig as described above, then change all passwords (including root) created after installation.

Appropriate options were also added to libuser, pam, and shadow-utils to support these password hashing algorithms. authconfig configures necessary options automatically, so it is usually not necessary to modify them manually:

  • New values of the crypt_style option and new options for both hash_rounds_min and hash_rounds_max are now supported in the [defaults] section of /etc/libuser.conf. For more information, refer to man libuser.conf.

  • New options sha256, sha512, and rounds are now supported by the pam_unix PAM module. For more information, refer to /usr/share/doc/pam-[pam version]/txts/README.pam_unix.

  • The following new options in /etc/login.defs are now supported by shadow-utils:

    • ENCRYPT_METHOD — Specifies the encryption methos to be used. Valid values are DES, MD5, SHA256, SHA512. If this option is defined, MD5_CRYPT_ENAB is ignored.

    • SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS — Specifies the number of hashing rounds to use if ENCRYPT_METHOD is set to SHA256 or SHA512. If neither option is set, a default value is chosen by glibc. If only one option is set, the encryption method specifies the number of rounds.

      If both options are used, they specify an inclusive interval from which the number of rounds is chosen randomly. The selected number of rounds is limited to the inclusive interval [1000, 999999999].


nfsroot is fully supported in this update. This allows users to run Red Hat Enterprise Linux 5.2 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:

  • Writable directories that hold system files (for example, /tmp, /var, and /etc) must be replicated for each client and mounted independently with no sharing between clients. To do so, perform the following steps:

    1. Configure the client's root file system to boot in read-only mode. To do so, replace READONLY with yes in /etc/sysconfig/readonly-root.

    2. Run cat /etc/rwtab to view a default list of directories and files mounted by each client in the format [type] [path].

      [type] can be either empty (an empty path), dirs (a directory tree that is copied, but is empty), or files (a file or directory tree copied intact).

    3. If any other files or directories need to writable but are not in /etc/rwtab, list them in the same format (i.e. [type] [path]) in a file under /etc/rwtab.d/.

  • SWAP is not supported over NFS.

  • 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.

OFED in comps.xml

The group OpenFabrics Enterprise Distribution is now included in comps.xml. This group contains components used for high-performance networking and clustering (for example, InfiniBand and Remote Direct Memory Access).

Further, the Workstation group has been removed from comps.xml in the Red Hat Enterprise Linux 5.2 Client version. This group only contained the openib package, which is now part of the OpenFabrics Enterprise Distribution group.


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

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

  • monitor the use of locking primitives

  • expose deadlocks

  • gather data

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

This updated version of frysk includes the following new utilities:

  • fauxv

  • fdebuginfo

  • fdebugrpm

  • ferror

  • fexe

  • fmaps

In addition to this, ftrace can now perform signal and function symbol tracing. In previous releases, ftrace could only perform system call tracing.

frysk was introduced in Red Hat Enterprise Linux 5, and is still included in this release as a Technology Preview. For more information about frysk, refer to

Driver Updates

General Driver/Platform Updates
  • The driver that allows hot docking/undocking of laptops is now updated to eliminate specific panic situations (for example, when a laptop fails to initialize correctly). This update also adds new sysfs entries, most notably:

    • /sys/devices/platform/dock.0/docked — read-only; indicates whether the laptop is docked on a docking station.

    • /sys/devices/platform/dock.0/undock — write-only; writing to this file initiates an "undock" request to the firmware.

    • /sys/devices/platform/dock.0/uid — displays the unique ID (UID) of the docking station.

  • Added the necessary PCI IDs to support the Intel E7221 Graphic Controller.

  • Added the necessary sub-device IDs to support the PCI-Express icom WAN adapter.

  • i2c-piix4 kernel module is now enabled to support the AMD SBX00 SMBus.

  • The following kernel configuration flags are now enabled to enhance kernel panic handling for Intelligent Platform Management Interface (IPMI):

    • CONFIG_IPMI_PANIC_EVENT — when a panic occurs, the IPMI message handler generates an IPMI event describing the panic to each interface registered with the message handler.

    • CONFIG_IPMI_PANIC_STRING — when a panic occurs, OEM events containing the panic string are generated.

    In addition to this, IPMI now supports the IBM Bladecenter QS21 and QS22.

  • The tlclk driver is now included to support the Intel MPCBL0050 systems.

  • All PCI-X configuration registers (up to 4096 bytes) are now accessible.

  • The maximum length of the kernel command line is now 2,048 bytes. To use this increased maximum length, upgrade the grub package.

  • Dynamic acceleration is now supported. This allows a core to run at a higher-than-normal frequency when all CPUs (as a whole) are operating below maximum power.

  • High-Definition Multimedia Interface (HDMI) audio is now supported on AMD ATI integrated chipsets.

  • The Intel Xorg driver now provides enhanced support for i915 (and later) chips. This driver is also the default driver now for such chips.

    Basic runtime multi-head support is provided by the intel Xorg driver. Selecting a resolution with the System => Preferences => Screen Resolution tool (gnome-display-properties) will set that resolution on all connected outputs.

  • The Sony/Philips Digital Interconnect Format (S/PDIF) port on the Dell D/Dock Expansion Station is now supported by the Dell M4300 and M6300 Precision Workstations. This allows digital audio output through the S/PDIF port on the Dell D/Dock Expansion Station when either the M4300 or M6300 is docked.

  • bnx2x: driver added to provide support for bcm5710 hardware.

  • tg3: updated to version 3.86. This update enables support for BroadCom 5761 and 5784 devices.

  • lpfc: updated to version This update applies several devloss fixes, and enables support for the following:

    • 1, 2, 4, and 8GB auto-rate negotiation.

    • FC-SP DH-CHAP Authentication.

    • The latest HBAnyware configuration utility, which is also part of the driver master kit. This enables GUI-based driver configuration (including fibre channel and TCP/IP remote storage area network management), diagnostics (loopback and diagnostics dump) and FC-SP/Authentication Diffie-Hellman CHAP (DH-CHAP).

    • LPe1250, LPe1252, LPe12000 and LPe12002 (2, 4, and 8Gb capable HBAs).

    • NPIV virtual ports.

  • megaraid_sas: updated to version 3.15. This applies several upstream changes, most notably:

    • Added the following module parameters:

      • fast_load: enables the driver to load faster by skipping physical device check.

      • cmd_per_lun: sets the maximum number of commands per logical unit.

      • max_sectors: sets the maximum number of sectors per I/O command.

      • poll_mode_io: enables support for polling (i.e. reduced interrupt operations). When poll_mode_io is set, commands will also be completed from the I/O path.

    • Added support for hibernation.

    • SYNCHRONIZE_CACHE is now blocked by the driver.

  • aacraid: updated to version 1.1.5-2453. This applies several upstream changes, most notably:

    • Fixed a bug that caused aacraid to use an incorrect dma mapping mask during firmware assert recovery.

    • Added the capability to issue a hardware reset to the adapter via sysfs. In line with this, the following check features were also added:

      • check_interval — for checking adapter health

      • update_interval — for revising time intervals used by adapter

      • check_reset — for blocking adapter checks/resets

    • Added a SYNCHRONIZE_CACHE call to implement a more effective cache flushing schedule. This helps reduce application stalls resulting from multiple applications issuing I/O commands to the storage device.

    • Replaced all if/else packet formations with platform function calls.

    • VPD inquiry pages are now supported. This ensures that when an array is created, the metadata stored on the physical device is issued a unique serial number. This serial number remains constant throughout array morphing or migration to other controllers.

  • qla2xxx: updated to version 8.02.00-k5. This update to qla2xxx adds support for the following:

    • EHAFT, a QLogic host bus adapter mechanism that provides activity information about fibre channel devices.

    • N_Port ID Virtualization (NPIV), which allows multiple N_Port IDs to share a single physical N_Port. This allows you to tie virtualized guests to fibre-channel identifiers, allowing those guests to migrate between hosts while retaining their access in the storage area network.

    • 8GB fibre-channel devices.

    • PCI EE error handling.

    This update also applies several improvements provided from upstream.

  • mpt fusion: updated to version 3.04.05. This update provides several changes, most notably:

    • On-the-fly logging (via the sysfs shost attribute) is now supported.

    • Added new sysfs shost attributes that provide the following:

      • board_name

      • board_assembly

      • board_tracer

      • unique_id

      • version_bios

      • version_fw

      • version_product

      • version_mpi

      • version_nvdata_default

      • version_nvdata_persistent

      • debug_level

      • io_delay

      • device_delay

    • task_abort calls are no longer sent to hidden RAID components and volumes.

    • Changes related to fibre channel:

      • Brocade, a rebranded FC949E fibre channel controller, is now supported.

      • Link speeds are now displayed when the driver is loaded and whenever the link speed changes.

      • High-priority request queueing is now used instead of the handshake/doorbell system when sending management requests for SAS or fibre channel.

    • Changes related to parallel SCSI:

      • ATTO UL4D, a rebranded SPI 1030 controller, is now supported.

      • mptspi_target_destroy is now declared as static.

Kernel-Related Updates

This release applies following kernel bug fixes:

  • Executing binaries with more than 2GB of debug information no longer fails.

  • When shutting down a database, all allocated hugepages are now released upon shutdown.

  • invalidate_mapping_pages() calls no longer cause soft lockups.

  • A bug that delayed oomkill from launching in a timely fashion (on systems with large memory) is now fixed.

  • A bug that caused soft lockup warnings when allocating memory on a system with large memory is now fixed.

  • 32-bit NFS clients can now correctly process 64-bit inode numbers.

  • The kernel now asserts Data Terminal Ready (DTR) signals before printing to serial ports during boot time. DTR assertion is required by some devices. Kernel boot messages are now printed to serial consoles on such devices.

  • The kernel parameter ide0=noprobe no longer causes a kernel panic.

This kernel update also features the following enhancements:

  • Added a new kernel parameter: /proc/sys/vm/flush_mmap_pages. This parameter specifies whether or not memory-mapped file pages should be flushed to disk by kupdate while the memory map is active. Valid values for this parameter are 1 (enable memory mapping by kupdate) and 0 (disable memory mapping by kupdate). The default value for this parameter is 1.

    To configure this parameter, use echo [1 or 0] /proc/sys/vm/flush_mmap_pages. Setting this parameter to 0 does the following:

    • kupdate will not flush dirty memory-mapped file pages as long as the memory map is active.

    • All dirty file pages will be asynchronously flushed to disk only as soon as the memory map is deactivated.

    If you set /proc/sys/vm/flush_mmap_pages to 0, it is advisable that you use another application to manually sync memory-mapped pages to disk.

  • Added a new kernel parameter: /proc/sys/kernel/sched_interactivity. This parameter allows you to tune the CPU scheduler's interactivity estimator. The interactivity estimator allows interactive processes to acquire more CPU time without causing CPU starvation in other processes.

    To configure this parameter, use echo [interactivity_level] > /proc/sys/kernel/sched_interactivity, where [interactivity_level] can be any of the following:

    • 2 — interactivity estimator is fully activated.

    • 1 — provides a weaker affinity to interactive processes than 2, but avoids CPU starvation under certain scheduling patterns.

    • 0 — any bias or affinity towards interactive processes is disabled.

  • kprobe now supports kretprobe_blacklist[].

  • Core dump masking is now supported. This allows a core dump process to skip the shared memory segments of a process when creating a core dump file. This feature also allows you to select whether or not to dump anonymous shared memory for each process.

    When a process is dumped, all anonymous memory is written to a core file as long as the size of the core file isn't limited. In some cases, you may want to prevent some memory segments (such as huge shared memory) from being dumped. Conversely, you may also want to save file-backed memory segments into a core file, in addition to individual files.

    For these purposes, you can use /proc/[pid]/coredump_filter to specify which memory segments of the [pid] process is dumped. coredump_filter is a bitmask of memory types. If a bitmask is set, memory segments of the corresponding memory type are dumped.

    The following memory types are supported:

    • 0x0 — anonymous private memory

    • 0x1 — anonymous shared memory

    • 0x2 — file-backed private memory

    • 0x3 — file-backed shared memory

    To set a bitmask for [pid], simply echo the corresponding bitmask to /proc/[pid]/coredump_filter. For example, to prevent a dump of all shared memory segments attached to process 1111, use:

    echo 0x1 > /proc/1111/coredump_filter

    The default value of coredump_filter is 0x3, which specifies that all anonymous memory segments are dumped. Also, note that regardless of the bitmask status, MMIO pages (such as frame buffers) are never dumped and vDSO pages are always dumped

    When a new process is created, the process inherits the bitmask status from its parent. As such, it is recommended that you set up coredump_filter before the program runs. To do so, echo the desired bitmask to /proc/self/coredump_filter before running the program.

  • audit can now trace and display per-session user activity.

  • REV UDF file sizes larger than 1GB are now supported.

  • Lock contention tracing and lockdep are now supported. These features provide in-depth information about spinlocks held in the kernel, which in turn help developers in driver debugging.

In addition to these, this release also features the following kernel updates:

  • The enumeration order of PCI devices has changed on several platforms to have NICs appear in the order they are labeled on the chassis and how the BIOS numbers them. The affected platforms are as follows:

    • Dell PowerEdge R900

    • HP ProLiant DL385 G2

    • HP ProLiant DL585 G2

    • HP Proliant DL580 G5

    Note that this change affects new installations only. If you prefer the old enumeration order, use the kernel parameter pci=nobfsort.

  • You can now determine the resource limit (rlimit) of a process. To do so, run cat /proc/[pid]/limits.

  • The maximum soft lockup timeout is now increased from 60 seconds to 300 seconds for systems that have a large number of CPUs. A soft lockup occurs when a CPU reports a memory starvation while it is unable to access a memory node accessed by other CPUs.

    In this release, you can also adjust the trigger limit for soft lockup warnings. To do so, use the following command (as root):

    echo [time] > /proc/sys/kernel/softlockup_thresh

    Replace [time] with the desired number of seconds before a soft lockup warning should be triggered. By default, this value is set to 10 (seconds).

  • show_mem() output now includes the total number of pagecache pages.

  • MSI-X is no longer enabled by default. To enable MSI-X, use the kernel module parameter ql2xenablemsix.


This section contains information about updates made to Red Hat Enterprise Linux suite of Virtualization tools.

  • When entering the second stage of a Windows™ Server 2003 installation, you no longer need to manually edit /etc/xen/[name of guest machine] to continue. The current user interface now allows you to change media on CD-ROMs attached to the guest.

  • The Virtual Machine Manager (virt-manager) included in this release now allows users to specify kernel boot parameters to the paravirtualized guest installer.

  • A wrong address translation (which can lead to a crashed guest) no longer occurs if a guest is running a PAE kernel with more than 3,840MB of RAM. As such, you no longer need to use the 64-bit kernel if you intend to run guests with more than 4GB of physical RAM under Rapid Virtualization Indexing (RVI).

  • During the lifetime of dom0, you can now create guests (i.e. xm create) more than 32,750 times.

  • When using virt-manager to add disks to an existing guest, duplicate entries are no longer created in the guest's /etc/xen/[domain name] configuration file.

Known Issues
  • Migrating paravirtualized guests through xm migrate [domain] [dom0 IP address] does not work.

  • Repeated live migration of paravirtualized guests between two hosts may cause one host to panic. If a host is rebooted after migrating a guest out of the system and before migrating the same guest back, the panic will not occur.

  • Running 16 cores or more using AMD Rev F processors may result in system resets when performing fully-virtualized guest installations.

  • When installing Red Hat Enterprise Linux 5 on a fully virtualized SMP guest, the installation may freeze. This can occur when the host (dom0) is running Red Hat Enterprise Linux 5.2.

    To prevent this, set the guest to use a single processor using the install. You can do this by using the --vcpus=1 option in virt-install. Once the installation is completed, you can set the guest to SMP by modifying the allocated vcpus in virt-manager.

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.

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.

ALUA Mode on EMC Clariion

Explicit active-passive failover (ALUA) mode using dm-multipath on EMC Clariion storage is now available. This mode is provided as per T10 specifications, but is provided in this release only as a technology preview.

For more information about T10, refer to


The radeon_tp driver is now included in this release as a Technology Preview. This driver enables the ATI R500/R600 chipsets.

This driver also features the following capabilities:

  • Modesetting on R500/R600 chipsets

  • 2D acceleration on R500 chipsets

  • Shadow framebuffer acceleration on R600 chipsets


FreeIPMI is now included in this update as a Technology Preview. FreeIPMI is a collection of Intelligent Platform Management IPMI system software. It provides in-band and out-of-band software, along with a development library conforming to the Intelligent Platform Management Interface (IPMI v1.5 and v2.0) standards.

For more information about FreeIPMI, refer to

TrouSerS and tpm-tools

TrouSerS and tpm-tools are included in this release to enable use of Trusted Platform Module (TPM) hardware.TPM hardware features include (among others):

  • Creation, storage, and use of RSA keys securely (without being exposed in memory)

  • Verification of a platform's software state using cryptographic hashes

TrouSerS is an implementation of the Trusted Computing Group's Software Stack (TSS) specification. You can use TrouSerS to write applications that make use of TPM hardware. tpm-tools is a suite of tools used to manage and utilize TPM hardware.

For more information about TrouSerS, refer to


eCryptfs is a stacked cryptographic file system for Linux. It mounts on individual directories in existing mounted lower file systems such as EXT3; there is no need to change existing partitions or file systems in order to start using eCryptfs.

eCryptfs stores cryptographic metadata in the header of each file written to the lower file system. This enables you to copy encrypted files between hosts or directly onto backup media. Files encrypted and copied in this manner can be decrypted with the proper key.

This release's version of eCryptfs provides several key management options, including protection based on passphrases and public keys. Below is a list of other fully functional features:

  • Interactive and non-interactive mounting.

  • Compatibility with SELinux.

  • Cryptographic metadata storage in both xattrs and file headers.

At present, the following issues still exist with eCryptfs:

  • direct_IO is not implemented.

  • Complex I/O patterns within the mmap implementation in eCryptfs may cause data corruption in some cases.

  • eCryptfs cannot be used for root file systems.

For more information about eCryptfs, refer to You can also refer to and for basic setup information.


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.

While much improved since its introduction in Red Hat Enterprise Linux 5, GFS2 remains a Technology Preview. Benchmark tests indicate faster performance on the following:

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

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

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

  • direct I/O to preallocated files

  • NFS file handle lookups

  • df, as allocation information is now cached

In addition, GFS2 also features the following changes:

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

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

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

  • nanosecond timestamps are now supported

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

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

  • file system sizes above 16TB are now supported

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

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.

It is highly recommended that those interested in testing stateless code read the HOWTO at and join

The enabling infrastructure pieces for Stateless Linux were originally introduced in Red Hat Enterprise Linux 5.


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:

  • A lightly modified X server.

  • 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.

mac80211 802.11a/b/g WiFi protocol stack (mac80211)

The mac80211 stack (formerly known as the devicescape/d80211 stack) enables the iwlwifi 4965GN wireless driver for Intel Wifi Link 4965 hardware. This stack allows certain wireless devices to connect to any Wi-Fi network.

Although the stack is already accepted upstream, the stability of this stack is yet to be verified through testing. As such, this stack is included in this release as a Technology Preview.


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.

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:

  • /usr/share/doc/scsi-target-utils-[version]/README

  • /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.


The firewire-sbp2 module is still 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:

  • IPv4

  • pcilynx host controllers

  • multi-LUN storage devices

  • non-exclusive access to storage devices

In addition, the following issues still exist in FireWire:

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

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

Resolved Issues

  • Netapp devices can now complete failback (after a previously-failed path is restored) within a reasonable time with the default dm-multipath configuration.

  • system-config-kickstart now supports package selection through the Red Hat Network plugin.

  • kudzu can now properly parse ifcfg-* files that contain quotes around the HWADDR or SUBCHANNELS parameters. In addition, kudzu no longer modifies network configurations on device change if the device's HWADDR is not specified.

  • Running netstat with the -A inet or -A inet6 option (on a system where sctp was not added to the kernel) no longer terminates abnormally. Note, however, that netstat will display the following warning message when invoked with the -s option:

    netstat: no support for `AF INET (sctp)' on this system.
  • The nohide export option is no longer required on referral exports (i.e. exports that specify a referral server). For more information on bound mounts, refer to man 5 exports.

  • The priority callouts of dm-multipath are now statically compiled. This fixes a problem that occurs when running dm-multipath on devices containing the root file system, which caused such devices to freeze during fibre-channel path faults.

  • parted can now understand and correctly print out Xen Virtual Device (XVD) partition labels. This enables paravirtualized guests to now use the parted utility. As such, you no longer need to use parted within dom0 to configure disk partitions on paravirtualized guests.

  • When upgrading to Red Hat Enterprise Linux 5.2 via Red Hat Network, you no longer need to manually import the redhat-beta key prior to upgrading.

  • It is no longer necessary to use the kernel parameter pci=nommconf for systems that use the AMD 8132 or HT 1000 chipsets.

    Note that the system will still restrict such bridges to using the PortIO CF8/CFC mechanism. However, bridges (including those on the same platform) that respond correctly to MMCONFIG cycles will use MMCONFIG, provided that the platform's BIOS correctly supports MMCONFIG.

  • Previous versions of Red Hat Enterprise Linux 5 on HP BL860c blade systems could hang during the IP information request stage of installation. When this occurred, you were required to reboot and perform the installation with Ethernet autonegotiation disabled.

    This issue is now fixed in this update.

  • Gemalto 64K smart cards now use readers compliant with Chip/Smart Card Interface Devices (CCID). Previously, this smart card used the built-in e-gate reader, which essentially meant that the card and reader were being inserted at the same time. As a result, coolkey did not consistently recognize Gemalto 64K smart cards.

    In this update, coolkey now works correctly with Gemalto 64k smart cards.

Known Issues

  • A bug in the updated /etc/udev/rules.d/50-udev.rules file prevents the creation of persistent names for tape devices with numbers higher than 9 in their names. For example, a persistent name will not be created for a tape device with a name of nst12.

    To work around this, add an asterisk (*) after each occurrence of the string nst[0-9] in /etc/udev/rules.d/50-udev.rules.

  • Nested paging can only translate 32-bit guest virtual addresses. This is because of a hardware feature that exists only in 32-bit physical address extensions (PAE).

    Also, note that on an AMD NPT system used as a PAE host, guests cannot have more than 4GB of memory.

  • The smartctl tool cannot properly read SMART parameters from SATA devices.

  • When using dm-multipath, if features "1 queue_if_no_path" is specified in /etc/multipath.conf then any process that issues I/O will hang until one or more paths are restored.

    To avoid this, set no_path_retry [N] in /etc/multipath.conf (where [N] is the number of times the system should retry a path). When you do, remove the features "1 queue_if_no_path" option from /etc/multipath.conf as well.

  • Enabling multiple installed versions of the same kernel module is not supported. In addition to this, a bug in the way kernel module versions are parsed can sometimes result in enabling an older version of the same kernel module.

    It is recommended that when you install a newer version of an installed kernel module, you should delete the older one first.

  • Executing kdump on an IBM Bladecenter QS21 or QS22 configured with NFS root will fail. To avoid this, specify an NFS dump target in /etc/kdump.conf.

  • IBM T60 laptops will power off completely when suspended and plugged into a docking station. To avoid this, boot the system with the argument acpi_sleep=s3_bios.

  • The QLogic iSCSI Expansion Card for the IBM Bladecenter provides both ethernet and iSCSI functions. Some parts on the card are shared by both functions. However, the current qla3xxx and qla4xxx drivers support ethernet and iSCSI functions individually. Both drivers do not support the use of ethernet and iSCSI functions simultaneously.

    Because of this limitation, successive resets (via consecutive ifdown/ifup commands) may hang the device. To avoid this, allow a 10-second interval after an ifup before issuing an ifdown. Also, allow the same 10-second interval after an ifdown before issuing an ifup. This interval allows ample time to stabilize and re-initialize all functions when an ifup is issued.

  • 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).

  • Boot-time logging to /var/log/boot.log is not available in Red Hat Enterprise Linux 5.2.

  • 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.

  • When using Red Hat Enterprise Linux 5.2 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.

  • 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
  • The IBM System z does not provide a traditional Unix-style physical console. As such, Red Hat Enterprise Linux 5.2 for the IBM System z does not support the firstboot functionality during initial program load.

    To properly initialize setup for Red Hat Enterprise Linux 5.2 on the IBM System z, run the following commands after installation:

    • /usr/bin/setup — provided by the setuptool package.

    • /usr/bin/rhn_register — provided by the rhn-setup package.

  • When a LUN is deleted on a configured storage system, 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:

  • Running the multipath command with the -ll option can cause the command to hang if one of the paths is on a blocking device. Note that the driver does not fail a request after some time if the device does not respond.

    This is caused by the cleanup code, which waits until the path checker request either completes or fails. To display the current multipath state without hanging the command, use multipath -l instead.

  • 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.

  • When running the bare-metal (non-Virtualized) kernel, the X server may not be able to retrieve EDID information from the monitor. When this occurs, the graphics driver will be unable to display resolutions highers than 800x600.

    To work around this, add the following line to the ServerLayout section of /etc/X11/xorg.conf:

    Option "Int10Backend" "x86emu"
  • Upgrading pm-utils from a Red Hat Enterprise Linux 5.2 Beta version of pm-utils will fail, resulting in the following error:

    error: unpacking of archive failed on file /etc/pm/sleep.d: cpio: rename

    To prevent this from occurring, delete the /etc/pm/sleep.d/ directory prior to upgrading. If /etc/pm/sleep.d contains any files, move those files to /etc/pm/hooks/.

  • Hardware testing for the Mellanox MT25204 has revealed that an internal error occurs under certain high-load conditions. When the ib_mthca driver reports a catastrophic error on this hardware, it is usually related to an insufficient completion queue depth relative to the number of outstanding work requests generated by the user application.

    Although the driver will reset the hardware and recover from such an event, all existing connections at the time of the error will be lost. This generally results in a segmentation fault in the user application. Further, if opensm is running at the time the error occurs, then you need to manually restart it in order to resume proper operation.

  • When upgrading from Red Hat Enterprise Linux 4.6 to Red Hat Enterprise Linux 5.1 (or later), a warning error will appear stating that the kernel module mptscsi was not found. To prevent this, edit /etc/modprobe.conf by changing mptscsi to mptscsih before upgrading.

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[1] This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0, available at