virt-manager 2.2 released

virt-manager v2.2 was released a while ago. One feature we contributed is the ability to choose a temporary boot device. Here is a quick write-up on how to use that feature.

virt-xml is a simple command line tool for editing domain definitions. It can be used interactively or for batch processing. Starting with virt-manager v2.2, virt-xml allows to boot a guest with a temporarily changed domain definition. This allows us to specify a boot configuration other than the guest's current domain definition. This is especially useful as the IBM Z architecture allows for only a single boot device, and therefore the boot order settings do not work the way they do on other platforms: If the first boot device fails to boot, there is no attempt made to boot from the next boot device. In addition, the architecture/BIOS has no support for interactively changing the boot device during the boot/IPL process.
Therefore, two new command line options were introduced:

• --no-define makes any changes to the domain definition transient (i.e. the guest's persistent domain XML will not be modified)
• --start allows the user to start the domain after the changes to the domain XML were applied

Here is a simple example illustrating the usage:

1. First, select the device which should be changed by a selector. In this example, the unique target name of the disk is used. See man virt-xml for a list of further possibilities.
2. Temporarily modify the boot order, assign the first slot to device vdc, and start the guest right away:
   
     $ virt-xml --edit target='vdc' --disk='boot_order=1' --start \
                --no-define sample_domain
   Note: If there was another device that already had boot_order=1, its boot order would be incremented.

As soon the guest is stopped, the changes will vanish.