与安装相关的注记

性能更新

驱动程序更新

内核相关事项更新

Virtualization

技术预览

解决的问题

已知的问题

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 红帽企业 Linux 5.2 is installed.

When installing 红帽企业 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 红帽企业 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.

注意：半虚拟化客户端将不会受到这个问题的影响。半虚拟化客户端通常使用 kernel-xen 内核。

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 红帽企业 Linux 5.1 or later from 红帽企业 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.

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.

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:

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:

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:

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.

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:

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.

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 红帽网络 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 红帽企业 Linux 5.2 via 红帽网络, 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 红帽企业 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.

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.

IBM Bladecenter 的 QLogic iSCSI Expansion Card 可提供以太网和 iSCSI 功能。网卡的某些部分可由两个功能共享。但目前 qla3xxx 和 qla4xxx 驱动程序独立支持以太网和 iSCSI 功能。这两个驱动程序都不支持同时使用以太网和 iSCSI 功能。

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.

安装了 Cisco Aironet MPI-350 无线网卡的笔记本可能会在使用有线以太端口进行网络安装的过程中，不能获取 DHCP 地址。

要解决这个问题，可以使用本地介质进行安装。或者，在安装之前您可以在笔记本的 BIOS 里禁用无线网卡（完成安装后，您可以再启用它）。

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

如果 X 正在运行且使用 vesa 之外的驱动，系统可能没有成功地重启至 kexec/kdump 内核。这个问题只存在于 ATI Rage XL 图形芯片组里。

如果 X 运行在安装了 ATI Rage XL 的系统上，为了成功地重启至 kexec/kdump 内核，请确保它使用 vesa 驱动。

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

这些信息指出某些 PCI-E 端口没有请求 IRQ。而且，这些信息不会以任何方式影响机器的操作。

当您以根用户身份登录时不会自动挂载可拆卸存储设备（比如 CD 和 DVD）。因此，您将需要用图形文件管理程序手动挂载这样的设备。

另外您还可以运行以下命令将设备挂载到 /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:

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.

如果出现这种情况，请删除所有设备和 /etc/lvm/.cache 文件中指定无效 LUN 的 mpath 链接条目。

找出这些条目是什么，运行以下命令：

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

就是说 3600d0230003414f30000203a7bc41a00 与两个 mpath 链接匹配，它们是：dm-4 和 dm-5。

因此，要删除 /etc/lvm/.cache 文件中的以下各行：

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

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.

如果 X 正在运行且使用 vesa 之外的驱动，系统可能没有成功地重启至 kexec/kdump 内核。这个问题只存在于 ATI Rage XL 图形芯片组里。

如果 X 运行在安装了 ATI Rage XL 的系统上，为了成功地重启至 kexec/kdump 内核，请确保它使用 vesa 驱动。

当运行裸机（非虚拟化的）内核时，X 服务器可能无法从监视器查询 EDID 信息。发生这种情况时，图形驱动程序将无法显示高于 800x600 的分辨率。

要解决这个问题，请在 /etc/X11/xorg.conf 文件的 ServerLayout 部分添加以下这行：

Option "Int10Backend" "x86emu"

Upgrading pm-utils from a 红帽企业 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/.

对 Mellanox MT25204 进行的硬件测试证明在这样高负载的情况下会出现内部错误。当 ib_mthca 驱动程序报告在此硬件中出现灾难性错误时，它通常和完成队列不足有关，这种现象是由用户应用程序生成的大量未完成的工作请求造成的。

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 红帽企业 Linux 4.6 to 红帽企业 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.