virtual-dsm/docs/environment.md

Environment Variables

This page lists all the environment variables that can be used to configure the container.

An empty default means the variable is unset and its value is determined automatically when applicable.

💽 Virtual DSM

Variable	Default	Description
URL		URL or local path to the DSM .pat installation file. Downloads the default Virtual DSM image automatically when unset.
HOST_MAC		MAC address reported to DSM.
HOST_MODEL		Synology host model reported to DSM.
HOST_SERIAL		Synology host serial number reported to DSM.
GUEST_SERIAL		Synology guest serial number reported to DSM.

🧠 CPU and Memory

Variable	Default	Description
CPU_CORES	2	Number of virtual CPU cores, such as 4, half, or max.
CPU_MODEL	host	QEMU CPU model.
CPU_FLAGS		Additional QEMU CPU flags.
HOST_CPU		CPU name reported to DSM. Selected automatically when unset.
KVM	Y	Enables KVM hardware acceleration.
RAM_SIZE	2G	Amount of RAM assigned to DSM, such as 2G, 4G, half, or max.
RAM_CHECK	Y	Checks whether enough host memory is available before starting DSM.

💾 Storage

Variable	Default	Description
DISK_SIZE	256G	Size of the main data disk.
DISK_FMT	raw	Disk image format: raw or qcow2.
DISK_TYPE	scsi	Disk device type, such as sata, scsi, nvme, or blk.
DISK_CACHE	none	Disk cache mode, such as none or writeback.
DISK_IO	native	Disk I/O mode, such as native, threads, or io_uring.
DISK_DISCARD	unmap	Discard/TRIM mode for the primary disk.
DISK_ROTATION	1	Rotation rate reported to the guest. Use 1 to identify the disk as an SSD.
DISK_FLAGS		Additional options used when creating qcow2 disks.
ALLOCATE	N	Preallocates space for the data disks.
STORAGE	/storage	Storage directory used for disks, settings, and downloads.

🌐 Networking

Variable	Default	Description
NETWORK		Network mode, such as nat, passt, slirp, or N to disable networking.
DHCP	N	Enables macvtap networking so DSM receives an address from the external LAN through DHCP.
HOST	VirtualDSM	Hostname assigned to DSM.
IP		Overrides the automatically selected guest IPv4 address.
MAC		Guest network adapter MAC address.
ADAPTER	virtio-net-pci	QEMU network adapter model.
DEV	eth0	Container network interface used as the uplink.
MTU		MTU assigned to the guest network interface.
MASK	255.255.255.0	IPv4 netmask.
TAP	dsm	TAP or macvtap interface name.
BRIDGE	docker	Bridge name used for NAT networking.
HOST_PORTS		Ports excluded from guest forwarding.
USER_PORTS		Additional ports to forward to DSM when using user-mode networking.
DNSMASQ_OPTS		Additional options passed to dnsmasq.
DNSMASQ_DEBUG	N	Enables dnsmasq debug output.
DNSMASQ_DISABLE	N	Disables the internal dnsmasq resolver.
PASST_OPTS		Additional options passed to passt.
PASST_DEBUG	N	Enables passt debug output.

🖥️ Display

Variable	Default	Description
DISPLAY	none	Display backend, such as vnc, disabled, or none.
VGA	none	QEMU video adapter model.
GPU	N	Enables Intel iGPU acceleration.
RENDERNODE	/dev/dri/renderD128	Render node used for GPU acceleration.

🔌 Shutdown

Variable	Default	Description
SHUTDOWN	Y	Enables graceful shutdown.
TIMEOUT	115	Maximum time, in seconds, to wait before forcing DSM to stop.
API_TIMEOUT	90	Maximum time, in seconds, to wait for the shutdown API call.

🐞 Debugging

Variable	Default	Description
DEBUG	N	Enables verbose debug output.
TRACE	N	Enables shell command tracing.
COM_PORT	2210	Internal communication port used by the DSM host helper.
CHR_PORT	12345	Internal character device port used by the DSM host helper.
HOST_DEBUG	N	Enables debug output for the DSM host helper.
ARGUMENTS		Additional raw arguments appended to the QEMU command line.