Red Hat ENTERPRISE 5.4 RELEASE NOTES, Manual

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• Fully virtualized guests cannot correct for time lost due to the domain being paused and unpaused.
Being able to correctly track the time across pause and unpause events is one of the advantages
of paravirtualized kernels. This issue is being addressed upstream with replaceable timers, so
fully virtualized guests will have paravirtualized timers. Currently, this code is under development
upstream and should be available in later versions of Red Hat Enterprise Linux.
(BZ#422531)
38
The following note applies to x86_64 Architectures:
• Upgrading a host (
dom0
) system to Red Hat Enterprise Linux 5.2 may render existing Red Hat
Enterprise Linux 4.5 SMP paravirtualized guests unbootable. This is more likely to occur when the
host system has more than 4GB of RAM.
To work around this, boot each Red Hat Enterprise Linux 4.5 guest in single CPU mode and
upgrade its kernel to the latest version (for Red Hat Enterprise Linux 4.5.z).
(BZ#253087
39
,
BZ#251013)
40
The following note applies to the ia64 Architecture:
• On some
Itanium
systems configured for console output to VGA, the
dom0
virtualized kernel may
fail to boot. This is because the virtualized kernel failed to properly detect the default console device
from the
Extensible Firmware Interface
(EFI) settings.
When this occurs, add the boot parameter
console=tty
to the kernel boot options in
/boot/efi/
elilo.conf
.
(BZ#249076)
41
• On some
Itanium
systems (such as the
Hitachi Cold Fusion 3e
), the serial port cannot be detected
in
dom0
when VGA is enabled by the EFI Maintenance Manager. As such, you need to supply the
following serial port information to the
dom0
kernel:
• Speed in bits/second
• Number of data bits
• Parity
•
io_base
address
These details must be specified in the
append=
line of the
dom0
kernel in
/boot/efi/
elilo.conf
. For example:
append="com1=19200,8n1,0x3f8 -- quiet rhgb console=tty0
console=ttyS0,19200n8"
In this example,
com1
is the serial port,
19200
is the speed (in bits/second),
8n1
specifies the
number of data bits/parity settings, and
0x3f8
is the
io_base
address.
(BZ#433771)
42
• Virtualization does not work on some architectures that use Non-Uniform Memory Access (NUMA).
As such, installing the virtualized kernel on systems that use NUMA will result in a boot failure.
Some installation numbers install the virtualized kernel by default. If you have such an installation
number and your system uses NUMA and does not work with kernel-xen, deselect the Virtualization
option during installation.
(BZ#293071)
43