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# Installing QEMU Guest Agent on CachyOS
- URL: https://dees.co/qemu-guest-agent/
- Published: 2026-08-31T21:51:18.000Z
- Updated: 2026-09-10T13:01:20.000Z
- Description: Install the QEMU Guest Agent on a CachyOS virtual machine to enable graceful shutdown, disk freezing during backups, and clock resync on an Unraid host with passthrough.
- Author: Garrett Dees
- Tags: CachyOS

The QEMU Guest Agent is a helper daemon that runs inside a virtual machine to allow direct communication and command execution between the hypervisor host and the guest operating system.

On Unraid, the required virtio channel (`org.qemu.guest_agent.0`) is added to the VM's XML automatically, so no host-side configuration is needed. Just install the agent in the guest.

```
sudo pacman -S qemu-guest-agent

sudo systemctl enable --now qemu-guest-agent.service
sudo systemctl status qemu-guest-agent.service

```

To verify the host can actually communicate with the guest, run this from the Unraid terminal:  
`virsh qemu-agent-command <vm-name> '{"execute":"guest-ping"}'`

A return of `{"return":{}}` confirms the channel is working end to end. Note that `systemctl status` alone only proves the daemon is running inside the guest; the ping proves the host can reach it.

Why this matters on a passthrough VM:

- **Graceful shutdown** \- Unraid's stop button issues a proper `guest-shutdown` instead of relying on ACPI, which a CachyOS VM with GPU passthrough may not handle cleanly.
- **Consistent disk state** \- with a passed-through SSD, the agent's `fsfreeze` support lets the host quiesce the filesystem during backups instead of catching it mid-write.
- **Clock resync after S3 sleep** \- when the host wakes from S3, the guest clock typically drifts. The agent lets the host correct it with `guest-set-time`.

The agent is a host-to-guest command channel by design, but it only listens on the virtio socket; it is not exposed to the network.