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Asked: 2012-03-27 02:14:17 +0800 CST

How to connect a cdrom device to a kvm/qemu domain (using command-line tools)?

  • 772

I have set up a virtual machine running Windows XP on my Ubuntu laptop. Using the virt-manager GUI application, I can insert a CD in my drive and go to Details→IDE CDROM 1 and click on the Connect button. Then the CD becomes available in my virtual machine.

How can I do the same through the command line? Obviously, I'd like to be able to disconnect from the command line too.

Note: I can start the VM from the command line using virsh start testbed (testbed being the name of the domain/VM).

kvm-virtualization optical-media virsh

5 Answers

  1. Best Answer

    If you defined no CDROM when you created your virtual machine, you can attach the device even to a running domain (virtual machine) by running the following command:

    virsh attach-disk testbed /dev/sr0 hdc --type cdrom

    If you already defined a CDROM, but it pointed to an ISO image, in my experience, you can still run the same command. The hdcpart needs to match the block device you have in the testbed virtual machine.

    When you want to point to an ISO image again, you replace /dev/sr0 to the filename on the host, something like

    virsh attach-disk testbed ~/virtio-win-0.1-22.iso hdc --type cdrom

    The documentation suggests using virsh update-device, but it is more labour to create an XML definition something like:

    <disk type='block' device='cdrom'>
  <driver name='qemu' type='raw'/>
  <source dev='/dev/sr0'/>
  <target dev='hdc' bus='ide'/>
  <readonly/>
</disk>

    If you are into this way, save something like that into a file (say ~/cdrom-real.xml) and then fire:

    virsh update-device testbed ~/cdrom-real.xml
    • 28

  2. Use virsh's qemu-monitor-command to pass the eject and change commands down to qemu.

    First use "info block" to get qemu's device name for your cdrom.

    virsh # qemu-monitor-command mirage --hmp --cmd "info block"
drive-virtio-disk0: type=hd removable=0 file=/home/daoist/mirage/mirage.qcow2 ro=0 drv=raw encrypted=0
drive-ide0-0-0: type=cdrom removable=1 locked=0 file=/home/daoist/iso/en_windows_7_ultimate_with_sp1_x64_dvd_u_677332.iso ro=1 drv=raw encrypted=0

    So in my case I'm interested in drive-ide0-0-0. So to change the disk, do this:

    virsh # qemu-monitor-command mirage --hmp --cmd "eject drive-ide0-0-0"
virsh # qemu-monitor-command mirage --hmp --cmd "change drive-ide0-0-0 /path/to/new.iso"
virsh #
    • 6

  3. Regarding the "info block" command above, the correct way to call it is like this:

     virsh qemu-monitor-command <domain> --hmp --cmd "info block"

    ie

     virsh qemu-monitor-command windows44407 --hmp --cmd "info block"
    • 2

  4. I was passing through a BluRay player that didn't work correctly unless I passed it through another way. Here is how I did it based on this article.

    https://lime-technology.com/forums/topic/33851-blu-ray-dvd-rom-passthrough/

    Find SCSI #:

    lsscsi

[root@kvmatrix ~]# lsscsi
[#:0:0:0]    cd/dvd  HL-DT-ST BD-RE  WH14NS40  1.03  /dev/sr0

    Edit Domain XML and add this:

    Note: Replace scsi_host# with the # found in lssci

    <controller type='scsi' index='0' model='virtio-scsi'/>
    <hostdev mode='subsystem' type='scsi'>
      <source>
        <adapter name='scsi_host#'/>
        <address type='scsi' bus='0' target='0' unit='0'/>
      </source>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </hostdev>

    I had to force the XML to be accepted as virsh edit gave errors, just press i and then reboot vm to test.

    • 0

  5. mount -t iso9660 /dev/sr0 /media

    You can use whatever device is set for your cdrom in /dev directory. Also /dev/cdrom is a link to the proper device on most Linux systems. The -t is for type of device you are mounting and iso9660 is the universal type for cdrom media.

    The mount point can be whatever you want obviously, just make sure it exists.

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