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05 Advanced quickemu configuration

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Martin Wimpress edited this page May 2, 2024 · 18 revisions

Command-line arguments

Here are the command line arguments for quickemu.

Usage
  quickemu --vm ubuntu.conf [optional params]

List of optional parameters:
  --access                          : Enable remote spice access support. 'local' (default), 'remote', 'clientipaddress'
  --braille                         : Enable braille support. Requires SDL.
  --delete-disk                     : Delete the disk image and EFI variables
  --delete-vm                       : Delete the entire VM and it's configuration
  --display                         : Select display backend. 'sdl' (default), 'gtk', 'none', 'spice' or 'spice-app'
  --fullscreen                      : Starts VM in full screen mode (Ctl+Alt+f to exit)
  --ignore-msrs-always              : Configure KVM to always ignore unhandled machine-specific registers
  --screen <screen>                 : Use specified screen to determine the window size.
  --screenpct <percent>             : Percent of fullscreen for VM if --fullscreen is not specified.
  --shortcut                        : Create a desktop shortcut
  --snapshot apply <tag>            : Apply/restore a snapshot.
  --snapshot create <tag>           : Create a snapshot.
  --snapshot delete <tag>           : Delete a snapshot.
  --snapshot info                   : Show disk/snapshot info.
  --status-quo                      : Do not commit any changes to disk/snapshot.
  --viewer <viewer>                 : Choose an alternative viewer. @Options: 'spicy' (default), 'remote-viewer', 'none'
  --width <width>                   : Set VM screen width. Does nothing without --height
  --height <height>                 : Set VM screen height. Does nothing without --width
  --ssh-port <port>                 : Set ssh-port manually
  --spice-port <port>               : Set spice-port manually
  --public-dir <path>               : Expose share directory. @Options: '' (default: xdg-user-dir PUBLICSHARE), '<directory>', 'none'
  --monitor <type>                  : Set monitor connection type. @Options: 'socket' (default), 'telnet', 'none'
  --monitor-telnet-host <ip/host>   : Set telnet host for monitor. (default: 'localhost')
  --monitor-telnet-port <port>      : Set telnet port for monitor. (default: '4440')
  --monitor-cmd <cmd>               : Send command to monitor if available. (Example: system_powerdown)
  --serial <type>                   : Set serial connection type. @Options: 'socket' (default), 'telnet', 'none'
  --serial-telnet-host <ip/host>    : Set telnet host for serial. (default: 'localhost')
  --serial-telnet-port <port>       : Set telnet port for serial. (default: '6660')
  --keyboard <type>                 : Set keyboard. @Options: 'usb' (default), 'ps2', 'virtio'
  --keyboard_layout <layout>        : Set keyboard layout.
  --mouse <type>                    : Set mouse. @Options: 'tablet' (default), 'ps2', 'usb', 'virtio'
  --usb-controller <type>           : Set usb-controller. @Options: 'ehci' (default), 'xhci', 'none'
  --sound-card <type>               : Set sound card. @Options: 'intel-hda' (default), 'ac97', 'es1370', 'sb16', 'none'
  --extra_args <arguments>          : Pass additional arguments to qemu
  --version                         : Print version

Connecting to your VM

SPICE

The following features are available while using the SPICE protocol:

  • Copy/paste between the guest and host
  • Host file sharing to the guest
  • USB device redirection

To use SPICE add --display spice to the Quickemu invocation, this requires that the spicy client is installed, available from the spice-client-gtk package in Debian/Ubuntu.

quickemu --vm ubuntu-22.04.conf --display spice

To enable copy/paste with a Windows guest, install SPICE Windows guest tools in the guest VM.

Headless

To start a VM with SPICE enabled, but no display attached use --display none. This requires that the spicy client is installed, available from the spice-client-gtk package in Debian/Ubuntu to connect to the running VM

quickemu --vm ubuntu-22.04.conf --display none

You can also use the .ports file in the VM directory to lookup what SSH and SPICE ports the VM is connected to.

cat ubuntu-22.04/ubuntu-22.04.ports

If, for example, the SSH port is set to 22220, and assuming your VM has a started SSH service (details vary by OS), you can typically SSH into it from the host as follows:

ssh -p 22220 your_vm_user@localhost

Accessibility

Qemu provides support for using BrlAPI to display braille output on a real or fake device.

quickemu --vm ubuntu-22.04.conf --braille --display sdl

BIOS and EFI

Since Quickemu 2.1.0 efi is the default boot option. If you want to override this behaviour then add the following line to the VM configuration to enable legacy BIOS.

boot="legacy"

CPU, RAM & Disks

By default, Quickemu will calculate the number of CPUs cores and RAM to allocate to a VM based on the specifications of your host computer. You can override this default behaviour and tune the VM configuration to your liking.

Add additional lines to your virtual machine configuration:

  • cpu_cores="4" - Specify the number of CPU cores allocated to the VM
  • ram="4G" - Specify the amount of RAM to allocate to the VM
  • disk_size="16G" - Specify the size of the virtual disk allocated to the VM

Disk preallocation

Preallocation mode (allowed values: off (default), metadata, falloc, full). An image with preallocated metadata is initially larger but can improve performance when the image needs to grow.

Specify what disk preallocation should be used, if any, when creating the system disk image by adding a line like this to your VM configuration.

preallocation="metadata"

CD-ROM disks

If you want to expose an ISO image from the host to guest add the following line to the VM configuration:

fixed_iso="/path/to/image.iso"

Floppy disks

If you're like Alan Pope you'll probably want to mount a floppy disk image in the guest. To do so add the following line to the VM configuration:

floppy="/path/to/floppy.img"

File Sharing

All File Sharing options will only expose ~/Public (or localised variations) for the current user to the guest VMs.

Samba

Supported on Linux, macOS and Windows guests. If smbd is available on the host, Quickemu will automatically enable the built-in QEMU support for exposing a Samba share from the host to the guest.

You can install the minimal Samba components on Ubuntu using:

sudo apt-get install --no-install-recommends samba

If everything is set up correctly, the smbd address will be printed when the virtual machine is started. For example:

     - smbd:     On guest: smb://10.0.2.4/qemu

If using a Windows guest, right-click on "This PC", click "Add a network location", and paste this address, removing smb: and replacing forward slashes with backslashes (in this example \\10.0.2.4\qemu).

SPICE WebDAV

Supported on Linux and Windows guests.

  • TBD

VirtIO-9P

Supported on Linux and macOS guests

  • TBD

Networking

Port forwarding

Add an additional line to the virtual machine configuration. For example:

port_forwards=("8123:8123" "8888:80")

In the example above:

  • Port 8123 on the host is forwarded to port 8123 on the guest.
  • Port 8888 on the host is forwarded to port 80 on the guest.

Disable networking

To completely disable all network interfaces in a guest VM add this additional line to your virtual machine configuration:

network="none"

Restricted networking

You can isolate the guest from the host (and broader network) using the restrict option, which will restrict networking to just the guest and any virtual devices.

This can be used to prevent software running inside the guest from phoning home while still providing a network inside the guest. Add this additional line to your virtual machine configuration:

network="restrict"

Bridged networking

To connect your virtual machine to a preconfigured network bridge, add an additional line to your virtual machine configuration:

network="br0"

If you want to have a persistent MAC address for your bridged network interface in the guest VM you can add macaddr to the virtual machine configuration. QEMU requires that the MAC address is in the range: 52:54:00:AB:00:00 - 52:54:00:AB:FF:FF

So you can specify a MAC addresses with something like this in the VM configuration:

macaddr="52:54:00:AB:51:AE"

USB redirection

Quickemu supports USB redirection via SPICE pass-through and host pass-through.

SPICE redirection (recommended)

Using SPICE for USB pass-through is easiest as it doesn't require any elevated permission:

  • Start Quickemu with --display spice and then
  • Select Input -> Select USB Device for redirection from the menu to choose which device(s) you want to attach to the guest.

Enabling SPICE redirection on NixOS

If you encounter this error when using NixOS as the host:

Error setting facl: Operation not permitted

Try setting the following option:

virtualisation.spiceUSBRedirection.enable = true;

Host redirection (NOT recommended)

USB host redirection is not recommended, it is provided purely for backwards compatibility for older versions of Quickemu. Using SPICE is preferred, see above.

Add an additional line to your virtual machine configuration. For example:

usb_devices=("046d:082d" "046d:085e")

In the example above:

  • The USB device with vendor_id 046d and product_id 082d will be exposed to the guest.
  • The USB device with vendor_id 046d and product_id 085e will be exposed to the guest.

If the USB devices are not writable, quickemu will display the appropriate commands to modify the USB device(s) access permissions, like this:

     - USB:      Host pass-through requested:
                  - Sennheiser Communications EPOS GTW 270 on bus 001 device 005 needs permission changes:
                    sudo chown -v root:user /dev/bus/usb/001/005
                    ERROR! USB permission changes are required 👆

TPM

Since Quickemu 2.2.0 a software emulated TPM device can be added to guest virtual machines. Just add tpm="on" to your VM configuration.

  • NOTE! quickget will automatically add this line to Windows 11 virtual machines.

Desktop shortcuts

Desktop shortcuts can be created for a VM, the shortcuts are saved in ~/.local/share/applications. Here is an example of how to create a shortcut.

quickemu --vm ubuntu-22.04-desktop.conf --shortcut

Screen and window size (Linux guests only)

qemu will always default to the primary monitor to display the VM's window.

Without the --screen option, quickemu will look for the size of the smallest monitor, and use a size that fits on said monitor.

The --screen option forces quickemu to use the size of the given monitor to compute the size of the window. It won't use that monitor to display the VM's window if it's not the primary monitor. This is useful if the primary monitor if not the smallest one, and if the VM's window doesn't need to be moved around.

The --screen option is also useful with the --fullscreen option, again because qemu will always use the primary monitor. In order for the fullscreen mode to work properly, the resolution of the VM's window must match the resolution of the screen.

To know which screen to use, type:

xrandr --listmonitors | grep -v Monitors

The command will output something like this:

 0: +*HDMI-0 2560/597x1440/336+1920+0  HDMI-0
 1: +DVI-D-0 1920/527x1080/296+0+0  DVI-D-0

The first number is what needs to be passed to the --screen option. For example:

quickemu --vm vm.conf --screen 0

The above uses the 2560x1440 screen to compute the window size, which Quickemu sizes to 2048x1152. Without the --screen option, Quickemu would have used the 1920x1080 monitor, resulting in a window size 1664x936.

The '--screenpct' is an optional integer value between 25 <= pct < 100 which will override system default screen sizes. The VM size will be pct of the chosen screen. If --fullscreen is chosen screen will be fullsize instead of being scaled down by --screenpct value.

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