Table of Contents

Initial debugging of VMs created with best practices

The following tips may be useful if you have created a VM via this article.

Proxmox VE - common dmesg Warnings in KVM/q35 VMs

These warnings appear in the guest dmesg of a properly configured Proxmox VM (q35, OVMF/UEFI, VirtIO SCSI as per the above “modern best practices”) and can safely be ignored.

ata1: SATA link down
ata3: SATA link down
ata4: SATA link down
ata5: SATA link down
ata6: SATA link down

The q35 chipset always emulates an AHCI SATA controller with 6 ports — even when only VirtIO SCSI is used. The unused ports simply report “no device found”. This is completely normal and harmless.

ata2 shows link up because the emulated CD/DVD-ROM drive is attached there.

Verdict: Safe to ignore.

shpchp: Slot Initialization Failed

shpchp 0000:05:01.0: pci_hp_register failed with error -16
shpchp 0000:05:01.0: Slot initialization failed

The Linux Standard Hot-Plug PCI driver tries to register itself on bridges that QEMU/q35 only partially emulates. This causes no functional problems and is a well-known cosmetic issue in KVM virtual machines.

Verdict: Safe to ignore.

powernow-k8: Power State Transitions Not Supported

powernow-k8: Power state transitions not supported (×12)

The guest kernel identifies the CPU as “AMD QEMU Virtual CPU” and loads the legacy powernow-k8 driver, which then discovers that CPU frequency scaling is not supported inside the VM. This is expected behavior when not using the host CPU type — the VM has no real CPU frequency management.

Verdict: Safe to ignore.

snd_hda_intel: No Codecs Found

snd_hda_intel 0000:00:1b.0: no codecs found!

No audio device is configured in the VM. The driver loads anyway but finds nothing to attach to. Either ignore this, or disable the audio device in the VM configuration to suppress the message.

Verdict: Safe to ignore, or remove the audio device in VM config.

What you should also see

Summary

Warning Cause Action
ata1-6: SATA link down Unused ports of q35 AHCI emulation Ignore
shpchp: Slot initialization failed Partial PCI bridge emulation in QEMU Ignore
powernow-k8: transitions not supported Legacy CPU freq driver, no scaling in VM Ignore
snd_hda_intel: no codecs found No audio device configured Ignore or remove audio