Hardware

Hardware configuration commands expose focused updates rather than requiring a complete VM request. Most hardware changes require a powered-off VM because Sylve must update the persistent libvirt domain definition.

Know which changes require shutdown

Command	May run while VM is active	Update behavior
config name	Yes	Replaces the name.
config description	Yes	Replaces the description.
config cpu	No	Replaces the complete CPU topology and pinning.
config memory	No	Replaces RAM size.
config vnc	No	Patches only supplied fields.
config serial	No	Replaces enabled state.
config pci	No	Replaces the complete PCI assignment list.
config tpm	No	Replaces TPM emulation state.

Wait for a shutdown or stop task to finish before using a command marked as requiring power-off.

Set name and description

Name and description may be changed while the VM is running:

doas sylve vms config name \
  --rid 301 \
  --name docs-alpine-configured \
  --json

doas sylve vms config description \
  --rid 301 \
  --description "Configured through the VM CLI" \
  --json

Each response identifies the configuration that was updated:

{
  "updated": true,
  "rid": 301,
  "configuration": "name"
}

An explicit empty description clears it. A VM name must satisfy the service’s normal name validation.

Replace CPU topology and pinning

CPU configuration is a full replacement. Supply sockets, cores per socket, threads per core, and an explicit pinning decision:

doas sylve vms config cpu \
  --rid 301 \
  --sockets 1 \
  --cores 2 \
  --threads 1 \
  --clear-pinning \
  --json

The resulting vCPU count is sockets multiplied by cores multiplied by threads. All topology values must be positive.

To pin virtual sockets to host CPU cores, repeat --pin using socket:core,core syntax:

doas sylve vms config cpu \
  --rid 301 \
  --sockets 2 \
  --cores 2 \
  --threads 1 \
  --pin 0:0,1 \
  --pin 1:2,3

--clear-pinning and --pin cannot be combined. Pinning is never removed merely because the option was omitted.

Change memory

RAM accepts human-readable byte sizes:

doas sylve vms config memory \
  --rid 301 \
  --ram 2GiB \
  --json

Loki accepted the change and returned "configuration": "memory". The complete VM inspection reports RAM in bytes when JSON output is requested.

Patch VNC settings

VNC is a partial update. Omitted settings, including the password, remain unchanged:

doas sylve vms config vnc \
  --rid 301 \
  --resolution 1280x720 \
  --wait=true \
  --json

Supported changes are:

• --enabled=true|false
• --port <1-65535>
• --bind <address>
• --resolution <width>x<height>
• --wait=true|false
• --password-file <host-path>
• --clear-password

--password-file and --clear-password are mutually exclusive. The file is read on the Sylve host, and ordinary inspection never returns the VNC password.

Review the VNC bind address

Binding VNC to a non-loopback address can expose the console to the network. Use authentication and host firewall controls appropriate to the environment.

Enable the serial console

Set serial state explicitly:

doas sylve vms config serial \
  --rid 301 \
  --enabled=true \
  --json

This enables bhyve serial plumbing. The guest must still configure its bootloader and operating system to use the serial console. The access guide covers preflight and connection commands.

Replace PCI passthrough assignments

PCI configuration replaces the complete assignment. Repeat --device-id for every passthrough record that should remain assigned:

doas sylve vms config pci \
  --rid 301 \
  --device-id 4 \
  --device-id 7 \
  --json

Clear all assignments explicitly:

doas sylve vms config pci --rid 301 --clear --json

On Loki, clearing an already-empty assignment returned "updated": false. This is a successful no-op, not an error.

PCI lists are not patches

Omitting an existing device from the repeated --device-id values removes that assignment. Confirm the complete intended list before submitting the command.

Configure TPM emulation

Enable or disable the emulated TPM:

doas sylve vms config tpm --rid 301 --enabled=true --json

Enabling TPM updates the VM definition and causes Sylve to manage the swtpm runtime and state files when the VM starts. Disabling it stops the associated TPM runtime when necessary.

Real CPU, memory, VNC, serial, PCI, and TPM configuration responses from Loki.

Use the interactive console

Place the RID immediately after the configuration leaf command:

vms config name 301 --name docs-alpine
vms config cpu 301 --sockets 1 --cores 2 --threads 1 --clear-pinning
vms config memory 301 --ram 2GiB
vms config vnc 301 --resolution 1280x720 --wait=true
vms config serial 301 --enabled=true
vms config pci 301 --clear
vms config tpm 301 --enabled=true

Use vms get 301 --json afterward to verify the resulting persistent configuration.