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Accepted
Belmin Fernandez
Asked: 2011-09-21 16:37:36 +0800 CST

Changing boot device for a QEMU-KVM virtual machine

  • 772

I am trying to change the boot device for a VM. I go to the VM's XML file in /etc/libvirt/qemu and set <boot dev='cdrom' />. Still, it attempts to boot from the harddrive instead of the cdrom.

I know I have an ISO image loaded on the CD-ROM virtual device.

Am I not doing this correctly? I tried shutting down the VM completely and starting it back up to no avail. Perhaps I need to reload the settings somehow?

Edit:

By request of @Selivanov:

$ libvirtd --version
libvirtd (libvirt) 0.8.7

And XML file:

<domain type='kvm'>
  <name>nimmy.example.com</name>
  <uuid>(SNIP)</uuid>
  <memory>524288</memory>
  <currentMemory>524288</currentMemory>
  <vcpu>1</vcpu>
  <os>
    <type arch='x86_64' machine='rhel6.1.0'>hvm</type>
    <boot dev='cdrom'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clock offset='utc'/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='none'/>
      <source file='/var/lib/libvirt/images/nimmy.img'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' unit='0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/home/nimmy/CentOS-6.0-x86_64-netinstall.iso'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' unit='0'/>
    </disk>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <interface type='network'>
      <mac address='(SNIP)'/>
      <source network='default'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='mouse' bus='ps2'/>
    <graphics type='vnc' port='-1' autoport='yes'/>
    <sound model='ac97'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='9216' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </memballoon>
  </devices>
</domain>
virtualization redhat kvm-virtualization libvirt qemu

2 Answers

  1. Best Answer

    If libvirt doesn't reload VM settings on start/stop, virsh edit command may help. And please write entire XML file and libvirt version

    Hmm... everything seems OK. Try adding

    <boot dev='hd'/>
<boot dev='cdrom'/>
<bootmenu enable='yes'/>

    to <os> section and look if cdrom appears in boot menu. Also try removing all <boot> records from <os> and adding 

    <boot order='1'/>

    to <disk> section

    • 9

  2. If the VM is down, look for a stored saved image under /var/lib/libvirt/qemu/save - it will keep the old parameters alive, despite changes made via virsh edit. I deleted such image in a similar case where it kept looking for an non-existent network interface (and failing to boot due to this).

    • 1