During migration kvm: warning: global PIIX4_PM.disable_s3=1 not used

[eugenefvdm]

Hello, can anyone please shed some light on these messages that seems to occur during every migration between say `hv02` and `hv05`:

2026-04-04 15:13:23 [hv05] kvm: warning: global PIIX4_PM.disable_s3=1 not used
2026-04-04 15:13:23 [hv05] kvm: warning: global PIIX4_PM.disable_s4=1 not used

 

[psalkiewicz]

These warnings are harmless but worth understanding. Here's what's going on:

PIIX4_PM is the emulated Intel PIIX4 Power Management controller that QEMU provides for older-style (i440FX/PIIX) VMs. The disable_s3 and disable_s4 properties control whether ACPI sleep states S3 (suspend-to-RAM) and S4 (hibernate) are advertised to the guest OS. The warning "not used" means those properties were set in the VM's configuration (or the migration packet), but the version of QEMU running on hv05 no longer accepts them as top-level global properties — they've been moved or renamed in newer QEMU versions.

- Check the VM's raw config on the source node:

cat /etc/pve/nodes/hv02/qemu-server/<VMID>.conf

Look for an args: line containing disable_s3 or disable_s4. If found, remove or update it.

- Check QEMU versions across your cluster — they should ideally be identical:

pvesh get /nodes/hv02/version
pvesh get /nodes/hv05/version

Or directly: qemu-system-x86_64 --version on each node.

- Check machine type — if the VM is using an old pinned machine type (e.g. pc-i440fx-2.x), upgrading it to a newer one may resolve the property mismatch. In the Proxmox GUI: VM → Hardware → Machine.