Red Hat ENTERPRISE 5.4 RELEASE NOTES, Manual

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Chapter 4. Known Issues
312
4.31. udev
udev provides a user-space API and implements a dynamic device directory, providing only the
devices present on the system. udev replaces devfs in order to provide greater hot plug functionality.
Netlink is a datagram oriented service, used to transfer information between kernel modules and user-
space processes.
• 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
.
(BZ#231990)
107
4.32. virt-manager
• Fully virtualized guests created through
virt-manager
may sometimes prevent the mouse from
moving freely throughout the screen. To work around this, use
virt-manager
to configure a USB
tablet device for the guest.
(BZ#223805)
108
4.33. virtio-win
VirtIO para-virtualized Windows(R) drivers for 32-bit and 64-bit Windows (R) guests.
• Low performance with UDP messages larger than 1024 is a known Microsoft issue:
http://
support.microsoft.com/default.aspx/kb/235257
. For the message larger than 1024 bytes follow the
workaround procedure detailed in the above Microsoft knowledgebase article.
(BZ#496592)
109
• Installation of Windows XP with the floppy containing guest drivers (in order to get the virtio-net
drivers installed as part of the installation), will return messages stating that the viostor.sys file could
not be found. viostor.sys is not part of the network drivers, but is on the same floppy as portions of
the virtio-blk drivers. These messages can be safely ignored, simply accept the installation's offer to
reboot, and the installation will continue normally.
BZ#513160
110
4.34. xen
• As of Red Hat Enterprise Linux 5.4, PCI devices connected to a single PCI-PCI bridge can no longer
be assigned to different PV guests. If the old, unsafe behaviour is required, disable pci-dev-assign-
strict-check in /etc/xen/xend-config.sxp.
(BZ#508310)
111
• Save operations should not be attempted on paused Xen domains. This will cause Xend to hang.
(BZ#504910)
112
• In live migrations of paravirtualized guests, time-dependent guest processes may function
improperly if the corresponding hosts' (dom0) times are not synchronized. Use NTP to synchronize
system times for all corresponding hosts before migration.
(BZ#426861)
113
• The Red Hat Enterprise Linux 3 kernel does not include SWIOTLB support. SWIOTLB support
is required for Red Hat Enterprise Linux 3 guests to support more than 4GB of memory on AMD
Opteron and Athlon-64 processors. Consequently, Red Hat Enterprise Linux 3 guests are limited to
4GB of memory on AMD processors.
(BZ#504187)
114