Querying XML File Configuration with libvirt Shell

Yes, you can query an XML configuration file for a libvirt domain (virtual machine) using the virsh command-line tool, which is the libvirt shell. Specifically, you can check for the presence of <kernel> and <initrd> elements in the domain’s XML configuration.

1. Dump the XML Configuration

Use the virsh dumpxml command to output the XML configuration of a specific domain. Replace <domain-name> with the name or UUID of your virtual machine.

virsh dumpxml <domain-name>

This will output the entire XML configuration of the domain to the terminal.

2. Search for `<kernel>` and `<initrd>` Elements

You can either manually inspect the output for the <kernel> and <initrd> elements, or you can use tools like grep to filter the output.

For example, to check if <kernel> and <initrd> are defined:

virsh dumpxml <domain-name> | grep -E '<kernel>|<initrd>'

This will display any lines containing <kernel> or <initrd> if they exist in the XML configuration.

3. Example XML Configuration

If the domain is configured to use a custom kernel and initrd, the relevant part of the XML might look like this:

<os>
  <type arch='x86_64' machine='pc-i440fx-2.9'>hvm</type>
  <kernel>/path/to/kernel</kernel>
  <initrd>/path/to/initrd</initrd>
  <cmdline>root=/dev/sda1 console=ttyS0</cmdline>
</os>

In this example, the <kernel> and <initrd> elements are defined with paths to the kernel and initrd files.

4. Edit the XML Configuration (Optional)

If you need to modify the <kernel> or <initrd> elements, you can edit the XML configuration using:

virsh edit <domain-name>

This will open the XML configuration in your default text editor, allowing you to make changes.

5. Check for Direct Kernel Boot

If the domain is configured for direct kernel boot, the <kernel> and <initrd> elements will be present. If not, these elements will be absent, and the domain will typically boot from a BIOS or UEFI configuration.

Summary

Use virsh dumpxml <domain-name> to view the XML configuration.
Use grep to filter for <kernel> and <initrd> elements.
Use virsh edit <domain-name> to modify the configuration if needed.

This approach allows you to query and inspect the XML configuration of a libvirt domain to determine if <kernel> and <initrd> elements are defined.