Spice agent for Linux

The spice agent for Linux consists of 2 parts, a daemon spice-vdagentd and a per X-session process spice-vdagent. The daemon gets started in Spice guests through a Sys-V initscript or a systemd unit. The per X-session gets automatically started in desktop environments which honor /etc/xdg/autostart, and under gdm.

The main daemon needs to know which X-session daemon is in the currently active X-session (think switch user functionality) for this console kit or systemd-logind (compile time option) is used. If no session info is available only one X-session agent is allowed.

Features:

• Client mouse mode (no need to grab mouse by client, no mouse lag) this is handled by the daemon by feeding mouse events into the kernel via uinput. This will only work if the active X-session is running a spice-vdagent process so that its resolution can be determined.
• Automatic adjustment of the X-session resolution to the client resolution
• Support of copy and paste (text and images) between the active X-session and the client. This supports both the primary selection and the clipboard.
• Support for transferring files from the client to the agent
• Full support for multiple displays using Xrandr, this requires a new enough xorg-x11-drv-qxl driver, as well as a new enough host.
• Limited support for multiple displays using Xinerama.
• Limited support for setups with multiple Screens (multiple qxl devices each mapped to their own screen)

Install

From inside your virtual machine (e.g., GNOME Boxes), use your guest system’s package manager to install.

For example, if you’re running a Debian/Ubuntu derivative in a VM, use:

sudo apt install spice-vdagent

How it works

All vdagent communications on the guest side run over a single pipe which gets presented to the guest os as a virtio serial port.

Under windows this virtio serial port has the following name:

\\\\.\\Global\\com.redhat.spice.0

Under Linux this virtio serial port has the following name:

/dev/virtio-ports/com.redhat.spice.0

To enable the virtio serial port you need to pass the following params on the qemu cmdline:

-device virtio-serial-pci,id=virtio-serial0,max_ports=16,bus=pci.0,addr=0x5 \
-chardev spicevmc,name=vdagent,id=vdagent \
-device virtserialport,nr=1,bus=virtio-serial0.0,chardev=vdagent,name=com.redhat.spice.0