Virtualization; Known Issues - Red Hat ENTERPRISE LINUX 5.3 - RELEASE NOTES Release Note

1.4. Virtualization

• A bug in the IDE/ATA driver stack that could prevent a system using kernel-xen from booting into
the kdump environment is now fixed. In previous releases, this occurred if the system encountered
a kernel panic while an IDE device was performing I/O and the IDE device was being controlled by a
device driver other than libata.
• A softlockup may have occurred when creating a guest with a large amount of memory.
Consequently, a call trace of the error was displayed on both the dom0 and the other guest. In this
update, this issue has been resolved.
• On systems with large amounts of memory (ie 256GB or more), setting up the dom0 could exhaust
the hypervisor memory heap. To work around this, the xenheap and dom0_size command line
arguments had to be set to valid values for the system. In this update, the hypervisor has been
updated to automatically set these values to a default of 32GB, which resolves this issue.
• Due to technical problems with passing TX checksum offload information between paravirtual
domains, the use of TX checksum offload in conjunction with NAT for traffic originating from another
domain is not supported. TX checksum offload can be used together with NAT as long as the NAT
rule is applied in the domain where the traffic originates.
Note that this also applies to fully virtualised domains using paravirtual network drivers. Fully
virtualised domains using fully virtualised drivers are not affected as they do not support TX
checksum offload at all.

1.5. Known Issues

• Previous versions of the 5.3 Release Notes stated that the CD-ROM/DVD-ROM unit on Dell
PowerEdge R905 servers does not work with Red Hat Enterprise Linux 5. This note was included by
error, and does not apply to Red Hat Enterprise Linux 5.3.
• kdump now serializes drive creation registration with the rest of the kdump process. Consequently,
kdump may hang waiting for IDE drives to be initialized. In these cases, it is recommended that IDE
disks not be used with kdump.
• Improvements have been made to the 'nv' driver, enhancing suspend and resume support on some
systems equipped with nVidia GeForce 8000 and 9000 series devices. Due to technical limitations,
this will not enable suspend/resume on all hardware.
• pirut sorts some package lists using the textual representation of a package, which is inconsistent
with the textual representation method used in yum. As such, some package lists (e.g. Optional
Packages list) in pirut may not display names in alphabetical order.
• The Hypervisor outputs messages regarding attempts by any guest to write to an MSR. Such
messages contain the statement Domain attempted WRMSR. These messages can be safely
ignored; furthermore, they are rate limited and should pose no performance risk.
• When upgrading from Red Hat Enterprise Linux 4 Workstation to 5 Server, OpenOffice will no
longer work correctly with SELinux. This is because the Red Hat Enterprise Linux version of
OpenOffice is built using an incorrect library. As a result, SELinux will prevent OpenOffice from
accessing any shared libraries, causing OpenOffice to fail.
To work around this, update the SELinux context to allow OpenOffice to access shared libraries. To
do so, run the following commands:
Virtualization
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