Chapter 40. Virtualization

When using the serial console through KVM, holding down an arrow key for an extended period of time to navigate in the GRUB 2 menu results in erratic behavior. To work around this problem, avoid the rapid input caused by holding an arrow key down for a longer time.

The Hyper-V manager supports shrinking a GPT-partitioned disk on a guest if there is free space after the last partition, by allowing the user to drop the unused last part of the disk. However, this operation will silently delete the secondary GPT header on the disk, which may trigger error messages when guest examines the partition table (for example, with parted(8)). This is a known limit of Hyper-V.

To work around this, it is possible to manually restore the secondary GPT header with the gdisk(8) expert command e, after shrinking the GPT disk. This also occurs when using Hyper-V's Expand option, but can also be fixed with the parted(8) tool.

When installing Red Hat Enterprise Linux 7 from other sources than the network, network device names are not specified by default in the interface configuration files (this is done with a DEVICE= line). As a consequence, creating a network bridge by using the virsh iface-bridge command fails with an error message. To work around the problem, add DEVICE= lines into the /etc/sysconfig/network-scripts/ifcfg-* files.

Currently, Common Access Card (CAC) smart cards emulated with QEMU are not accepted by ActivClient software. To work around this problem, disable the pcscd daemon, provision a Windows KVM guest, preconfigure it in the virt-viewer tool and select the USB redirection option, install the ActivClient software, and reboot the KVM guest. With this setup, ActivClient accepts the emulated CAC card.

Due to limitations on floppy file size, the virtual floppy disk (VFD) files in the virtio-win packages do not contain a Windows 10 folder. If a user needs to install Windows 10 drivers from a VFD, they can use the Windows 8 or Windows 8.1 drivers instead. Alternatively, the Windows 10 drivers can be installed from the ISO file in the /usr/share/virtio-win/ directory.

Virtual machines (VMs) created on Red Hat Enterprise Linux 6 that have no graphics card (such as VMs created using the virt-install utility with the --graphics none option) do not show the boot menu on the serial console anymore after migrating to Red Hat Enterprise Linux 7 hosts. To work around this problem, add the <bios useserial='yes'/> line to the domain.xml file, which allows the boot menu to display as expected.

Note that if the XML file is modified this way, it should not be used on Red Hat Enterprise Linux 6.6 or earlier, as these do not benefit from changes introduced for BZ#1162759.