Part of CachyOS Wiki Notes. From the official CachyOS wiki (last updated 2025-11-24).
QEMU User Session
Why run a VM in a user session instead of a root session: networking and 3D acceleration via translation.
Networking
A root session forbids the VM from forwarding ports and uses NAT instead — the VM can see the world, but the world cannot see the VM, it sees your PC. Fine in general, but you cannot connect into the VM from outside the machine (e.g. over ssh), because there is nothing to connect to.
3D acceleration
A root session forbids VMM from using the render node /dev/dri/renderD128, and cripples qemu-cli — a regular user can barely make use of root qemu.
How to enable it
- In the main VMM window,
File -> Add Connection.... - In the
Hypervisor:dropdown, selectQEMU/KVM user session. - Create VMs as described in QEMU and VMM Setup, in User mode rather than Root mode.
No packages, services, group changes, or config edits — the whole change is that one VMM connection setting.