## Qemu/KVM Virtual Machines
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Qemu (short form for Quick Emulator) is an open source hypervisor that emulates a
physical computer. From the perspective of the host system where Qemu is
running, Qemu is a user program which has access to a number of local resources
like partitions, files, network cards which are then passed to an
emulated computer which sees them as if they were real devices.
A guest operating system running in the emulated computer accesses these
devices, and runs as if it were running on real hardware. For instance, you can pass
an ISO image as a parameter to Qemu, and the OS running in the emulated computer
will see a real CD-ROM inserted into a CD drive.
Qemu can emulate a great variety of hardware from ARM to Sparc, but Proxmox VE is
only concerned with 32 and 64 bits PC clone emulation, since it represents the
overwhelming majority of server hardware. The emulation of PC clones is also one
of the fastest due to the availability of processor extensions which greatly
speed up Qemu when the emulated architecture is the same as the host
architecture.
You may sometimes encounter the term KVM (Kernel-based Virtual Machine).
It means that Qemu is running with the support of the virtualization processor
extensions, via the Linux KVM module. In the context of Proxmox VE Qemu and
KVM can be used interchangeably, as Qemu in Proxmox VE will always try to load the KVM
module.
Qemu inside Proxmox VE runs as a root process, since this is required to access block
and PCI devices.
Emulated devices and paravirtualized devices
The PC hardware emulated by Qemu includes a mainboard, network controllers,
SCSI, IDE and SATA controllers, serial ports (the complete list can be seen in
the kvm(1) man page) all of them emulated in software. All these devices
are the exact software equivalent of existing hardware devices, and if the OS
running in the guest has the proper drivers it will use the devices as if it
were running on real hardware. This allows Qemu to runs unmodified operating
systems.
This however has a performance cost, as running in software what was meant to
run in hardware involves a lot of extra work for the host CPU. To mitigate this,
Qemu can present to the guest operating system paravirtualized devices, where
the guest OS recognizes it is running inside Qemu and cooperates with the
hypervisor.
Qemu relies on the virtio virtualization standard, and is thus able to present
paravirtualized virtio devices, which includes a paravirtualized generic disk
controller, a paravirtualized network card, a paravirtualized serial port,
a paravirtualized SCSI controller, etc &#8230;
It is highly recommended to use the virtio devices whenever you can, as they
provide a big performance improvement. Using  the virtio generic disk controller
versus an emulated IDE controller will double the sequential write throughput,
as measured with bonnie++(8). Using the virtio network interface can deliver
up to three times the throughput of an emulated Intel E1000 network card, as
measured with iperf(1). [See this benchmark on the KVM wiki
https://www.linux-kvm.org/page/Using_VirtIO_NIC]
Virtual Machines Settings
Generally speaking Proxmox VE tries to choose sane defaults for virtual machines
(VM). Make sure you understand the meaning of the settings you change, as it
could incur a performance slowdown, or putting your data at risk.
General Settings
General settings of a VM include
the Node : the physical server on which the VM will run
the VM ID: a unique number in this Proxmox VE installation used to identify your VM
Name: a free form text string you can use to describe the VM
Resource Pool: a logical group of VMs
OS Settings
When creating a virtual machine (VM), setting the proper Operating System(OS)
allows Proxmox VE to optimize some low level parameters. For instance Windows OS
expect the BIOS clock to use the local time, while Unix based OS expect the
BIOS clock to have the UTC time.
System Settings
On VM creation you can change some basic system components of the new VM. You
can specify which display type you want to use.
Additionally, the SCSI controller can be changed.
If you plan to install the QEMU Guest Agent, or if your selected ISO image
already ships and installs it automatically, you may want to tick the Qemu
Agent box, which lets Proxmox VE know that it can use its features to show some
more information, and complete some actions (for example, shutdown or
snapshots) more intelligently.
Proxmox VE allows to boot VMs with different firmware and machine types, namely
SeaBIOS and OVMF. In most cases you want to switch from
the default SeaBIOS to OVMF only if you plan to use
PCIe pass through. A VMs Machine Type defines the
hardware layout of the VM&#8217;s virtual motherboard. You can choose between the
default Intel 440FX or the
Q35
chipset, which also provides a virtual PCIe bus, and thus may be desired if
one wants to pass through PCIe hardware.
Hard Disk
Bus/Controller
Qemu can emulate a number of storage controllers:
the IDE controller, has a design which goes back to the 1984 PC/AT disk
controller. Even if this controller has been superseded by recent designs,
each and every OS you can think of has support for it, making it a great choice
if you want to run an OS released before 2003. You can connect up to 4 devices
on this controller.
the SATA (Serial ATA) controller, dating from 2003, has a more modern
design, allowing higher throughput and a greater number of devices to be
connected. You can connect up to 6 devices on this controller.
the SCSI controller, designed in 1985, is commonly found on server grade
hardware, and can connect up to 14 storage devices. Proxmox VE emulates by default a
LSI 53C895A controller.
A SCSI controller of type VirtIO SCSI is the recommended setting if you aim for
performance and is automatically selected for newly created Linux VMs since
Proxmox VE 4.3. Linux distributions have support for this controller since 2012, and
FreeBSD since 2014. For Windows OSes, you need to provide an extra iso
containing the drivers during the installation.
If you aim at maximum performance, you can select a SCSI controller of type
VirtIO SCSI single which will allow you to select the IO Thread option.
When selecting VirtIO SCSI single Qemu will create a new controller for
each disk, instead of adding all disks to the same controller.
The VirtIO Block controller, often just called VirtIO or virtio-blk,
is an older type of paravirtualized controller. It has been superseded by the
VirtIO SCSI Controller, in terms of features.
Image Format
On each controller you attach a number of emulated hard disks, which are backed
by a file or a block device residing in the configured storage. The choice of
a storage type will determine the format of the hard disk image. Storages which
present block devices (LVM, ZFS, Ceph) will require the raw disk image format,
whereas files based storages (Ext4, NFS, CIFS, GlusterFS) will let you to choose
either the raw disk image format or the QEMU image format.
the QEMU image format is a copy on write format which allows snapshots, and
  thin provisioning of the disk image.
the raw disk image is a bit-to-bit image of a hard disk, similar to what
 you would get when executing the dd command on a block device in Linux. This
 format does not support thin provisioning or snapshots by itself, requiring
 cooperation from the storage layer for these tasks. It may, however, be up to
 10% faster than the QEMU image format. [See this benchmark for details
 https://events.static.linuxfound.org/sites/events/files/slides/CloudOpen2013_Khoa_Huynh_v3.pdf]
the VMware image format only makes sense if you intend to import/export the
 disk image to other hypervisors.
Cache Mode
Setting the Cache mode of the hard drive will impact how the host system will
notify the guest systems of block write completions. The No cache default
means that the guest system will be notified that a write is complete when each
block reaches the physical storage write queue, ignoring the host page cache.
This provides a good balance between safety and speed.
If you want the Proxmox VE backup manager to skip a disk when doing a backup of a VM,
you can set the No backup option on that disk.
If you want the Proxmox VE storage replication mechanism to skip a disk when starting
 a replication job, you can set the Skip replication option on that disk.
As of Proxmox VE 5.0, replication requires the disk images to be on a storage of type
zfspool, so adding a disk image to other storages when the VM has replication
configured requires to skip replication for this disk image.
Trim/Discard
If your storage supports thin provisioning (see the storage chapter in the
Proxmox VE guide), you can activate the Discard option on a drive. With Discard
set and a TRIM-enabled guest OS [TRIM, UNMAP, and discard
https://en.wikipedia.org/wiki/Trim_%28computing%29], when the VM&#8217;s filesystem
marks blocks as unused after deleting files, the controller will relay this
information to the storage, which will then shrink the disk image accordingly.
For the guest to be able to issue TRIM commands, you must enable the Discard
option on the drive. Some guest operating systems may also require the
SSD Emulation flag to be set. Note that Discard on VirtIO Block drives is
only supported on guests using Linux Kernel 5.0 or higher.
If you would like a drive to be presented to the guest as a solid-state drive
rather than a rotational hard disk, you can set the SSD emulation option on
that drive. There is no requirement that the underlying storage actually be
backed by SSDs; this feature can be used with physical media of any type.
Note that SSD emulation is not supported on VirtIO Block drives.
IO Thread
The option IO Thread can only be used when using a disk with the
VirtIO controller, or with the SCSI controller, when the emulated controller
 type is  VirtIO SCSI single.
With this enabled, Qemu creates one I/O thread per storage controller,
rather than a single thread for all I/O. This can increase performance when
multiple disks are used and each disk has its own storage controller.
CPU
A CPU socket is a physical slot on a PC motherboard where you can plug a CPU.
This CPU can then contain one or many cores, which are independent
processing units. Whether you have a single CPU socket with 4 cores, or two CPU
sockets with two cores is mostly irrelevant from a performance point of view.
However some software licenses depend on the number of sockets a machine has,
in that case it makes sense to set the number of sockets to what the license
allows you.
Increasing the number of virtual CPUs (cores and sockets) will usually provide a
performance improvement though that is heavily dependent on the use of the VM.
Multi-threaded applications will of course benefit from a large number of
virtual CPUs, as for each virtual cpu you add, Qemu will create a new thread of
execution on the host system. If you&#8217;re not sure about the workload of your VM,
it is usually a safe bet to set the number of Total cores to 2.
It is perfectly safe if the overall number of cores of all your VMs
is greater than the number of cores on the server (for example, 4 VMs each with
4 cores (= total 16) on a machine with only 8 cores). In that case the host
system will balance the QEMU execution threads between your server cores, just
like if you were running a standard multi-threaded application. However, Proxmox VE
will prevent you from starting VMs with more virtual CPU cores than physically
available, as this will only bring the performance down due to the cost of
context switches.
Resource Limits
In addition to the number of virtual cores, you can configure how much resources
a VM can get in relation to the host CPU time and also in relation to other
VMs.
With the cpulimit (&#8220;Host CPU Time&#8221;) option you can limit how much CPU time
the whole VM can use on the host. It is a floating point value representing CPU
time in percent, so 1.0 is equal to 100%, 2.5 to 250% and so on. If a
single process would fully use one single core it would have 100% CPU Time
usage. If a VM with four cores utilizes all its cores fully it would
theoretically use 400%. In reality the usage may be even a bit higher as Qemu
can have additional threads for VM peripherals besides the vCPU core ones.
This setting can be useful if a VM should have multiple vCPUs, as it runs a few
processes in parallel, but the VM as a whole should not be able to run all
vCPUs at 100% at the same time. Using a specific example: lets say we have a VM
which would profit from having 8 vCPUs, but at no time all of those 8 cores
should run at full load - as this would make the server so overloaded that
other VMs and CTs would get to less CPU. So, we set the cpulimit limit to
4.0 (=400%). If all cores do the same heavy work they would all get 50% of a
real host cores CPU time. But, if only 4 would do work they could still get
almost 100% of a real core each.
VMs can, depending on their configuration, use additional threads, such
as for networking or IO operations but also live migration. Thus a VM can show
up to use more CPU time than just its virtual CPUs could use. To ensure that a
VM never uses more CPU time than virtual CPUs assigned set the cpulimit
setting to the same value as the total core count.
The second CPU resource limiting setting, cpuunits (nowadays often called CPU
shares or CPU weight), controls how much CPU time a VM gets compared to other
running VMs. It is a relative weight which defaults to 100 (or 1024 if the
host uses legacy cgroup v1). If you increase this for a VM it will be
prioritized by the scheduler in comparison to other VMs with lower weight. For
example, if VM 100 has set the default 100 and VM 200 was changed to 200,
the latter VM 200 would receive twice the CPU bandwidth than the first VM 100.
For more information see man systemd.resource-control, here CPUQuota
corresponds to cpulimit and CPUWeight corresponds to our cpuunits
setting, visit its Notes section for references and implementation details.
The third CPU resource limiting setting, affinity, controls what host cores
the virtual machine will be permitted to execute on. E.g., if an affinity value
of 0-3,8-11 is provided, the virtual machine will be restricted to using the
host cores 0,1,2,3,8,9,10, and 11. Valid affinity values are written in
cpuset List Format. List Format is a comma-separated list of CPU numbers and
ranges of numbers, in ASCII decimal.
CPU affinity uses the taskset command to restrict virtual machines to
a given set of cores. This restriction will not take effect for some types of
processes that may be created for IO. CPU affinity is not a security feature.
For more information regarding affinity see man cpuset. Here the
List Format corresponds to valid affinity values. Visit its Formats
section for more examples.
CPU Type
Qemu can emulate a number different of CPU types from 486 to the latest Xeon
processors. Each new processor generation adds new features, like hardware
assisted 3d rendering, random number generation, memory protection, etc &#8230;
Usually you should select for your VM a processor type which closely matches the
CPU of the host system, as it means that the host CPU features (also called CPU
flags ) will be available in your VMs. If you want an exact match, you can set
the CPU type to host in which case the VM will have exactly the same CPU flags
as your host system.
This has a downside though. If you want to do a live migration of VMs between
different hosts, your VM might end up on a new system with a different CPU type.
If the CPU flags passed to the guest are missing, the qemu process will stop. To
remedy this Qemu has also its own CPU type kvm64, that Proxmox VE uses by defaults.
kvm64 is a Pentium 4 look a like CPU type, which has a reduced CPU flags set,
but is guaranteed to work everywhere.
In short, if you care about live migration and moving VMs between nodes, leave
the kvm64 default. If you donât care about live migration or have a homogeneous
cluster where all nodes have the same CPU, set the CPU type to host, as in
theory this will give your guests maximum performance.
Custom CPU Types
You can specify custom CPU types with a configurable set of features. These are
maintained in the configuration file /etc/pve/virtual-guest/cpu-models.conf by
an administrator. See man cpu-models.conf for format details.
Specified custom types can be selected by any user with the Sys.Audit
privilege on /nodes. When configuring a custom CPU type for a VM via the CLI
or API, the name needs to be prefixed with custom-.
Meltdown / Spectre related CPU flags
There are several CPU flags related to the Meltdown and Spectre vulnerabilities
[Meltdown Attack https://meltdownattack.com/] which need to be set
manually unless the selected CPU type of your VM already enables them by default.
There are two requirements that need to be fulfilled in order to use these
CPU flags:
The host CPU(s) must support the feature and propagate it to the guest&#8217;s virtual CPU(s)
The guest operating system must be updated to a version which mitigates the
  attacks and is able to utilize the CPU feature
Otherwise you need to set the desired CPU flag of the virtual CPU, either by
editing the CPU options in the WebUI, or by setting the flags property of the
cpu option in the VM configuration file.
For Spectre v1,v2,v4 fixes, your CPU or system vendor also needs to provide a
so-called &#8220;microcode update&#8221; [You can use &#8216;intel-microcode&#8217; /
&#8216;amd-microcode&#8217; from Debian non-free if your vendor does not provide such an
update. Note that not all affected CPUs can be updated to support spec-ctrl.]
for your CPU.
To check if the Proxmox VE host is vulnerable, execute the following command as root:
for f in /sys/devices/system/cpu/vulnerabilities/*; do echo "${f##*/} -" $(cat "$f"); done
A community script is also available to detect is the host is still vulnerable.
[spectre-meltdown-checker https://meltdown.ovh/]
Intel processors
pcid
This reduces the performance impact of the Meltdown (CVE-2017-5754) mitigation
called Kernel Page-Table Isolation (KPTI), which effectively hides
the Kernel memory from the user space. Without PCID, KPTI is quite an expensive
mechanism [PCID is now a critical performance/security feature on x86
https://groups.google.com/forum/m/#!topic/mechanical-sympathy/L9mHTbeQLNU].
To check if the Proxmox VE host supports PCID, execute the following command as root:
# grep ' pcid ' /proc/cpuinfo
If this does not return empty your host&#8217;s CPU has support for pcid.
spec-ctrl
Required to enable the Spectre v1 (CVE-2017-5753) and Spectre v2 (CVE-2017-5715) fix,
in cases where retpolines are not sufficient.
Included by default in Intel CPU models with -IBRS suffix.
Must be explicitly turned on for Intel CPU models without -IBRS suffix.
Requires an updated host CPU microcode (intel-microcode &gt;= 20180425).
ssbd
Required to enable the Spectre V4 (CVE-2018-3639) fix. Not included by default in any Intel CPU model.
Must be explicitly turned on for all Intel CPU models.
Requires an updated host CPU microcode(intel-microcode &gt;= 20180703).
AMD processors
ibpb
Required to enable the Spectre v1 (CVE-2017-5753) and Spectre v2 (CVE-2017-5715) fix,
in cases where retpolines are not sufficient.
Included by default in AMD CPU models with -IBPB suffix.
Must be explicitly turned on for AMD CPU models without -IBPB suffix.
Requires the host CPU microcode to support this feature before it can be used for guest CPUs.
virt-ssbd
Required to enable the Spectre v4 (CVE-2018-3639) fix.
Not included by default in any AMD CPU model.
Must be explicitly turned on for all AMD CPU models.
This should be provided to guests, even if amd-ssbd is also provided, for maximum guest compatibility.
Note that this must be explicitly enabled when when using the "host" cpu model,
because this is a virtual feature which does not exist in the physical CPUs.
amd-ssbd
Required to enable the Spectre v4 (CVE-2018-3639) fix.
Not included by default in any AMD CPU model. Must be explicitly turned on for all AMD CPU models.
This provides higher performance than virt-ssbd, therefore a host supporting this should always expose this to guests if possible.
virt-ssbd should none the less also be exposed for maximum guest compatibility as some kernels only know about virt-ssbd.
amd-no-ssb
Recommended to indicate the host is not vulnerable to Spectre V4 (CVE-2018-3639).
Not included by default in any AMD CPU model.
Future hardware generations of CPU will not be vulnerable to CVE-2018-3639,
and thus the guest should be told not to enable its mitigations, by exposing amd-no-ssb.
This is mutually exclusive with virt-ssbd and amd-ssbd.
NUMA
You can also optionally emulate a NUMA
[https://en.wikipedia.org/wiki/Non-uniform_memory_access] architecture
in your VMs. The basics of the NUMA architecture mean that instead of having a
global memory pool available to all your cores, the memory is spread into local
banks close to each socket.
This can bring speed improvements as the memory bus is not a bottleneck
anymore. If your system has a NUMA architecture [if the command
numactl --hardware | grep available returns more than one node, then your host
system has a NUMA architecture] we recommend to activate the option, as this
will allow proper distribution of the VM resources on the host system.
This option is also required to hot-plug cores or RAM in a VM.
If the NUMA option is used, it is recommended to set the number of sockets to
the number of nodes of the host system.
vCPU hot-plug
Modern operating systems introduced the capability to hot-plug and, to a
certain extent, hot-unplug CPUs in a running system. Virtualization allows us
to avoid a lot of the (physical) problems real hardware can cause in such
scenarios.
Still, this is a rather new and complicated feature, so its use should be
restricted to cases where its absolutely needed. Most of the functionality can
be replicated with other, well tested and less complicated, features, see
Resource Limits.
In Proxmox VE the maximal number of plugged CPUs is always cores * sockets.
To start a VM with less than this total core count of CPUs you may use the
vpus setting, it denotes how many vCPUs should be plugged in at VM start.
Currently only this feature is only supported on Linux, a kernel newer than 3.10
is needed, a kernel newer than 4.7 is recommended.
You can use a udev rule as follow to automatically set new CPUs as online in
the guest:
SUBSYSTEM=="cpu", ACTION=="add", TEST=="online", ATTR{online}=="0", ATTR{online}="1"
Save this under /etc/udev/rules.d/ as a file ending in .rules.
Note: CPU hot-remove is machine dependent and requires guest cooperation.  The
deletion command does not guarantee CPU removal to actually happen, typically
it&#8217;s a request forwarded to guest OS using target dependent mechanism, such as
ACPI on x86/amd64.
Memory
For each VM you have the option to set a fixed size memory or asking
Proxmox VE to dynamically allocate memory based on the current RAM usage of the
host.
Fixed Memory Allocation
When setting memory and minimum memory to the same amount
Proxmox VE will simply allocate what you specify to your VM.
Even when using a fixed memory size, the ballooning device gets added to the
VM, because it delivers useful information such as how much memory the guest
really uses.
In general, you should leave ballooning enabled, but if you want to disable
it (like for debugging purposes), simply uncheck Ballooning Device or set
balloon: 0
in the configuration.
Automatic Memory Allocation
When setting the minimum memory lower than memory, Proxmox VE will make sure that the
minimum amount you specified is always available to the VM, and if RAM usage on
the host is below 80%, will dynamically add memory to the guest up to the
maximum memory specified.
When the host is running low on RAM, the VM will then release some memory
back to the host, swapping running processes if needed and starting the oom
killer in last resort. The passing around of memory between host and guest is
done via a special balloon kernel driver running inside the guest, which will
grab or release memory pages from the host.
[A good explanation of the inner workings of the balloon driver can be found here https://rwmj.wordpress.com/2010/07/17/virtio-balloon/]
When multiple VMs use the autoallocate facility, it is possible to set a
Shares coefficient which indicates the relative amount of the free host memory
that each VM should take. Suppose for instance you have four VMs, three of them
running an HTTP server and the last one is a database server. To cache more
database blocks in the database server RAM, you would like to prioritize the
database VM when spare RAM is available. For this you assign a Shares property
of 3000 to the database VM, leaving the other VMs to the Shares default setting
of 1000. The host server has 32GB of RAM, and is currently using 16GB, leaving 32
* 80/100 - 16 = 9GB RAM to be allocated to the VMs. The database VM will get 9 *
3000 / (3000 + 1000 + 1000 + 1000) = 4.5 GB extra RAM and each HTTP server will
get 1.5 GB.
All Linux distributions released after 2010 have the balloon kernel driver
included. For Windows OSes, the balloon driver needs to be added manually and can
incur a slowdown of the guest, so we don&#8217;t recommend using it on critical
systems.
When allocating RAM to your VMs, a good rule of thumb is always to leave 1GB
of RAM available to the host.
Network Device
Each VM can have many Network interface controllers (NIC), of four different
types:
Intel E1000 is the default, and emulates an Intel Gigabit network card.
the VirtIO paravirtualized NIC should be used if you aim for maximum
performance. Like all VirtIO devices, the guest OS should have the proper driver
installed.
the Realtek 8139 emulates an older 100 MB/s network card, and should
only be used when emulating older operating systems ( released before 2002 )
the vmxnet3 is another paravirtualized device, which should only be used
when importing a VM from another hypervisor.
Proxmox VE will generate for each NIC a random MAC address, so that your VM is
addressable on Ethernet networks.
The NIC you added to the VM can follow one of two different models:
in the default Bridged mode each virtual NIC is backed on the host by a
tap device, ( a software loopback device simulating an Ethernet NIC ). This
tap device is added to a bridge, by default vmbr0 in Proxmox VE. In this mode, VMs
have direct access to the Ethernet LAN on which the host is located.
in the alternative NAT mode, each virtual NIC will only communicate with
the Qemu user networking stack, where a built-in router and DHCP server can
provide network access. This built-in DHCP will serve addresses in the private
10.0.2.0/24 range. The NAT mode is much slower than the bridged mode, and
should only be used for testing. This mode is only available via CLI or the API,
but not via the WebUI.
You can also skip adding a network device when creating a VM by selecting No
network device.
You can overwrite the MTU setting for each VM network device. The option
mtu=1 represents a special case, in which the MTU value will be inherited
from the underlying bridge.
This option is only available for VirtIO network devices.
Multiqueue
If you are using the VirtIO driver, you can optionally activate the
Multiqueue option. This option allows the guest OS to process networking
packets using multiple virtual CPUs, providing an increase in the total number
of packets transferred.
When using the VirtIO driver with Proxmox VE, each NIC network queue is passed to the
host kernel, where the queue will be processed by a kernel thread spawned by the
vhost driver. With this option activated, it is possible to pass multiple
network queues to the host kernel for each NIC.
When using Multiqueue, it is recommended to set it to a value equal
to the number of Total Cores of your guest. You also need to set in
the VM the number of multi-purpose channels on each VirtIO NIC with the ethtool
command:
ethtool -L ens1 combined X
where X is the number of the number of vcpus of the VM.
You should note that setting the Multiqueue parameter to a value greater
than one will increase the CPU load on the host and guest systems as the
traffic increases. We recommend to set this option only when the VM has to
process a great number of incoming connections, such as when the VM is running
as a router, reverse proxy or a busy HTTP server doing long polling.
Display
QEMU can virtualize a few types of VGA hardware. Some examples are:
std, the default, emulates a card with Bochs VBE extensions.
cirrus, this was once the default, it emulates a very old hardware module
with all its problems. This display type should only be used if really
necessary [https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/
qemu: using cirrus considered harmful], for example, if using Windows XP or
earlier
vmware, is a VMWare SVGA-II compatible adapter.
qxl, is the QXL paravirtualized graphics card. Selecting this also
enables SPICE (a remote viewer protocol) for the
VM.
virtio-gl, often named VirGL is a virtual 3D GPU for use inside VMs that
  can offload workloads to the host GPU without requiring special (expensive)
  models and drivers and neither binding the host GPU completely, allowing
  reuse between multiple guests and or the host.
VirGL support needs some extra libraries that aren&#8217;t installed by
default due to being relatively big and also not available as open source for
all GPU models/vendors. For most setups you&#8217;ll just need to do:
apt install libgl1 libegl1
You can edit the amount of memory given to the virtual GPU, by setting
the memory option. This can enable higher resolutions inside the VM,
especially with SPICE/QXL.
As the memory is reserved by display device, selecting Multi-Monitor mode
for SPICE (such as qxl2 for dual monitors) has some implications:
Windows needs a device for each monitor, so if your ostype is some
version of Windows, Proxmox VE gives the VM an extra device per monitor.
Each device gets the specified amount of memory.
Linux VMs, can always enable more virtual monitors, but selecting
a Multi-Monitor mode multiplies the memory given to the device with
the number of monitors.
Selecting serialX as display type disables the VGA output, and redirects
the Web Console to the selected serial port. A configured display memory
setting will be ignored in that case.
USB Passthrough
There are two different types of USB passthrough devices:
Host USB passthrough
SPICE USB passthrough
Host USB passthrough works by giving a VM a USB device of the host.
This can either be done via the vendor- and product-id, or
via the host bus and port.
The vendor/product-id looks like this: 0123:abcd,
where 0123 is the id of the vendor, and abcd is the id
of the product, meaning two pieces of the same usb device
have the same id.
The bus/port looks like this: 1-2.3.4, where 1 is the bus
and 2.3.4 is the port path. This represents the physical
ports of your host (depending of the internal order of the
usb controllers).
If a device is present in a VM configuration when the VM starts up,
but the device is not present in the host, the VM can boot without problems.
As soon as the device/port is available in the host, it gets passed through.
Using this kind of USB passthrough means that you cannot move
a VM online to another host, since the hardware is only available
on the host the VM is currently residing.
The second type of passthrough is SPICE USB passthrough. This is useful
if you use a SPICE client which supports it. If you add a SPICE USB port
to your VM, you can passthrough a USB device from where your SPICE client is,
directly to the VM (for example an input device or hardware dongle).
BIOS and UEFI
In order to properly emulate a computer, QEMU needs to use a firmware.
Which, on common PCs often known as BIOS or (U)EFI, is executed as one of the
first steps when booting a VM. It is responsible for doing basic hardware
initialization and for providing an interface to the firmware and hardware for
the operating system. By default QEMU uses SeaBIOS for this, which is an
open-source, x86 BIOS implementation. SeaBIOS is a good choice for most
standard setups.
Some operating systems (such as Windows 11) may require use of an UEFI
compatible implementation instead. In such cases, you must rather use OVMF,
which is an open-source UEFI implementation. [See the OVMF Project https://github.com/tianocore/tianocore.github.io/wiki/OVMF]
There are other scenarios in which the SeaBIOS may not be the ideal firmware to
boot from, for example if you want to do VGA passthrough. [Alex
Williamson has a good blog entry about this
https://vfio.blogspot.co.at/2014/08/primary-graphics-assignment-without-vga.html]
If you want to use OVMF, there are several things to consider:
In order to save things like the boot order, there needs to be an EFI Disk.
This disk will be included in backups and snapshots, and there can only be one.
You can create such a disk with the following command:
# qm set &lt;vmid&gt; -efidisk0 &lt;storage&gt;:1,format=&lt;format&gt;,efitype=4m,pre-enrolled-keys=1
Where &lt;storage&gt; is the storage where you want to have the disk, and
&lt;format&gt; is a format which the storage supports. Alternatively, you can
create such a disk through the web interface with Add &#8594; EFI Disk in the
hardware section of a VM.
The efitype option specifies which version of the OVMF firmware should be
used. For new VMs, this should always be 4m, as it supports Secure Boot and
has more space allocated to support future development (this is the default in
the GUI).
pre-enroll-keys specifies if the efidisk should come pre-loaded with
distribution-specific and Microsoft Standard Secure Boot keys. It also enables
Secure Boot by default (though it can still be disabled in the OVMF menu within
the VM).
If you want to start using Secure Boot in an existing VM (that still uses
a 2m efidisk), you need to recreate the efidisk. To do so, delete the old one
(qm set &lt;vmid&gt; -delete efidisk0) and add a new one as described above. This
will reset any custom configurations you have made in the OVMF menu!
When using OVMF with a virtual display (without VGA passthrough),
you need to set the client resolution in the OVMF menu (which you can reach
with a press of the ESC button during boot), or you have to choose
SPICE as the display type.
Trusted Platform Module (TPM)
A Trusted Platform Module is a device which stores secret data - such as
encryption keys - securely and provides tamper-resistance functions for
validating system boot.
Certain operating systems (such as Windows 11) require such a device to be
attached to a machine (be it physical or virtual).
A TPM is added by specifying a tpmstate volume. This works similar to an
efidisk, in that it cannot be changed (only removed) once created. You can add
one via the following command:
# qm set &lt;vmid&gt; -tpmstate0 &lt;storage&gt;:1,version=&lt;version&gt;
Where &lt;storage&gt; is the storage you want to put the state on, and &lt;version&gt;
is either v1.2 or v2.0. You can also add one via the web interface, by
choosing Add &#8594; TPM State in the hardware section of a VM.
The v2.0 TPM spec is newer and better supported, so unless you have a specific
implementation that requires a v1.2 TPM, it should be preferred.
Compared to a physical TPM, an emulated one does not provide any real
security benefits. The point of a TPM is that the data on it cannot be modified
easily, except via commands specified as part of the TPM spec. Since with an
emulated device the data storage happens on a regular volume, it can potentially
be edited by anyone with access to it.
Inter-VM shared memory
You can add an Inter-VM shared memory device (ivshmem), which allows one to
share memory between the host and a guest, or also between multiple guests.
To add such a device, you can use qm:
# qm set &lt;vmid&gt; -ivshmem size=32,name=foo
Where the size is in MiB. The file will be located under
/dev/shm/pve-shm-$name (the default name is the vmid).
Currently the device will get deleted as soon as any VM using it got
shutdown or stopped. Open connections will still persist, but new connections
to the exact same device cannot be made anymore.
A use case for such a device is the Looking Glass
[Looking Glass: https://looking-glass.io/] project, which enables high
performance, low-latency display mirroring between host and guest.
Audio Device
To add an audio device run the following command:
qm set &lt;vmid&gt; -audio0 device=&lt;device&gt;
Supported audio devices are:
ich9-intel-hda: Intel HD Audio Controller, emulates ICH9
intel-hda: Intel HD Audio Controller, emulates ICH6
AC97: Audio Codec '97, useful for older operating systems like Windows XP
There are two backends available:
spice
none
The spice backend can be used in combination with SPICE while
the none backend can be useful if an audio device is needed in the VM for some
software to work. To use the physical audio device of the host use device
passthrough (see PCI Passthrough and
USB Passthrough). Remote protocols like Microsoftâs RDP
have options to play sound.
VirtIO RNG
A RNG (Random Number Generator) is a device providing entropy (randomness) to
a system. A virtual hardware-RNG can be used to provide such entropy from the
host system to a guest VM. This helps to avoid entropy starvation problems in
the guest (a situation where not enough entropy is available and the system may
slow down or run into problems), especially during the guests boot process.
To add a VirtIO-based emulated RNG, run the following command:
qm set &lt;vmid&gt; -rng0 source=&lt;source&gt;[,max_bytes=X,period=Y]
source specifies where entropy is read from on the host and has to be one of
the following:
/dev/urandom: Non-blocking kernel entropy pool (preferred)
/dev/random: Blocking kernel pool (not recommended, can lead to entropy
  starvation on the host system)
/dev/hwrng: To pass through a hardware RNG attached to the host (if multiple
  are available, the one selected in
  /sys/devices/virtual/misc/hw_random/rng_current will be used)
A limit can be specified via the max_bytes and period parameters, they are
read as max_bytes per period in milliseconds. However, it does not represent
a linear relationship: 1024B/1000ms would mean that up to 1 KiB of data becomes
available on a 1 second timer, not that 1 KiB is streamed to the guest over the
course of one second. Reducing the period can thus be used to inject entropy
into the guest at a faster rate.
By default, the limit is set to 1024 bytes per 1000 ms (1 KiB/s). It is
recommended to always use a limiter to avoid guests using too many host
resources. If desired, a value of 0 for max_bytes can be used to disable
all limits.
Device Boot Order
QEMU can tell the guest which devices it should boot from, and in which order.
This can be specified in the config via the boot property, for example:
boot: order=scsi0;net0;hostpci0
This way, the guest would first attempt to boot from the disk scsi0, if that
fails, it would go on to attempt network boot from net0, and in case that
fails too, finally attempt to boot from a passed through PCIe device (seen as
disk in case of NVMe, otherwise tries to launch into an option ROM).
On the GUI you can use a drag-and-drop editor to specify the boot order, and use
the checkbox to enable or disable certain devices for booting altogether.
If your guest uses multiple disks to boot the OS or load the bootloader,
all of them must be marked as bootable (that is, they must have the checkbox
enabled or appear in the list in the config) for the guest to be able to boot.
This is because recent SeaBIOS and OVMF versions only initialize disks if they
are marked bootable.
In any case, even devices not appearing in the list or having the checkmark
disabled will still be available to the guest, once it&#8217;s operating system has
booted and initialized them. The bootable flag only affects the guest BIOS and
bootloader.
Automatic Start and Shutdown of Virtual Machines
After creating your VMs, you probably want them to start automatically
when the host system boots. For this you need to select the option Start at
boot from the Options Tab of your VM in the web interface, or set it with
the following command:
# qm set &lt;vmid&gt; -onboot 1
Start and Shutdown Order
In some case you want to be able to fine tune the boot order of your
VMs, for instance if one of your VM is providing firewalling or DHCP
to other guest systems.  For this you can use the following
parameters:
Start/Shutdown order: Defines the start order priority. For example, set it
to 1 if
you want the VM to be the first to be started. (We use the reverse startup
order for shutdown, so a machine with a start order of 1 would be the last to
be shut down). If multiple VMs have the same order defined on a host, they will
additionally be ordered by VMID in ascending order.
Startup delay: Defines the interval between this VM start and subsequent
VMs starts. For example, set it to 240 if you want to wait 240 seconds before
starting other VMs.
Shutdown timeout: Defines the duration in seconds Proxmox VE should wait
for the VM to be offline after issuing a shutdown command. By default this
value is set to 180, which means that Proxmox VE will issue a shutdown request and
wait 180 seconds for the machine to be offline. If the machine is still online
after the timeout it will be stopped forcefully.
VMs managed by the HA stack do not follow the start on boot and
boot order options currently. Those VMs will be skipped by the startup and
shutdown algorithm as the HA manager itself ensures that VMs get started and
stopped.
Please note that machines without a Start/Shutdown order parameter will always
start after those where the parameter is set. Further, this parameter can only
be enforced between virtual machines running on the same host, not
cluster-wide.
If you require a delay between the host boot and the booting of the first VM,
see the section on Proxmox VE Node Management.
Qemu Guest Agent
The Qemu Guest Agent is a service which runs inside the VM, providing a
communication channel between the host and the guest. It is used to exchange
information and allows the host to issue commands to the guest.
For example, the IP addresses in the VM summary panel are fetched via the guest
agent.
Or when starting a backup, the guest is told via the guest agent to sync
outstanding writes via the fs-freeze and fs-thaw commands.
For the guest agent to work properly the following steps must be taken:
install the agent in the guest and make sure it is running
enable the communication via the agent in Proxmox VE
Install Guest Agent
For most Linux distributions, the guest agent is available. The package is
usually named qemu-guest-agent.
For Windows, it can be installed from the
Fedora
VirtIO driver ISO.
Enable Guest Agent Communication
Communication from Proxmox VE with the guest agent can be enabled in the VM&#8217;s
Options panel. A fresh start of the VM is necessary for the changes to take
effect.
It is possible to enable the Run guest-trim option. With this enabled,
Proxmox VE will issue a trim command to the guest after the following
operations that have the potential to write out zeros to the storage:
moving a disk to another storage
live migrating a VM to another node with local storage
On a thin provisioned storage, this can help to free up unused space.
Troubleshooting
VM does not shut down
Make sure the guest agent is installed and running.
Once the guest agent is enabled, Proxmox VE will send power commands like
shutdown via the guest agent. If the guest agent is not running, commands
cannot get executed properly and the shutdown command will run into a timeout.
SPICE Enhancements
SPICE Enhancements are optional features that can improve the remote viewer
experience.
To enable them via the GUI go to the Options panel of the virtual machine. Run
the following command to enable them via the CLI:
qm set &lt;vmid&gt; -spice_enhancements foldersharing=1,videostreaming=all
To use these features the Display of the virtual machine
must be set to SPICE (qxl).
Folder Sharing
Share a local folder with the guest. The spice-webdavd daemon needs to be
installed in the guest. It makes the shared folder available through a local
WebDAV server located at http://localhost:9843.
For Windows guests the installer for the Spice WebDAV daemon can be downloaded
from the
official SPICE website.
Most Linux distributions have a package called spice-webdavd that can be
installed.
To share a folder in Virt-Viewer (Remote Viewer) go to File &#8594; Preferences.
Select the folder to share and then enable the checkbox.
Folder sharing currently only works in the Linux version of Virt-Viewer.
Experimental! Currently this feature does not work reliably.
Video Streaming
Fast refreshing areas are encoded into a video stream. Two options exist:
all: Any fast refreshing area will be encoded into a video stream.
filter: Additional filters are used to decide if video streaming should be
  used (currently only small window surfaces are skipped).
A general recommendation if video streaming should be enabled and which option
to choose from cannot be given. Your mileage may vary depending on the specific
circumstances.
Troubleshooting
Shared folder does not show up
Make sure the WebDAV service is enabled and running in the guest. On Windows it
is called Spice webdav proxy. In Linux the name is spice-webdavd but can be
different depending on the distribution.
If the service is running, check the WebDAV server by opening
http://localhost:9843 in a browser in the guest.
It can help to restart the SPICE session.
Migration
If you have a cluster, you can migrate your VM to another host with
# qm migrate &lt;vmid&gt; &lt;target&gt;
There are generally two mechanisms for this
Online Migration (aka Live Migration)
Offline Migration
Online Migration
If your VM is running and no locally bound resources are configured (such as
passed-through devices), you can initiate a live migration with the --online
flag in the qm migration command evocation. The web-interface defaults to
live migration when the VM is running.
How it works
Online migration first starts a new QEMU process on the target host with the
incoming flag, which performs only basic initialization with the guest vCPUs
still paused and then waits for the guest memory and device state data streams
of the source Virtual Machine.
All other resources, such as disks, are either shared or got already sent
before runtime state migration of the VMs begins; so only the memory content
and device state remain to be transferred.
Once this connection is established, the source begins asynchronously sending
the memory content to the target. If the guest memory on the source changes,
those sections are marked dirty and another pass is made to send the guest
memory data.
This loop is repeated until the data difference between running source VM
and incoming target VM is small enough to be sent in a few milliseconds,
because then the source VM can be paused completely, without a user or program
noticing the pause, so that the remaining data can be sent to the target, and
then unpause the targets VM&#8217;s CPU to make it the new running VM in well under a
second.
Requirements
For Live Migration to work, there are some things required:
The VM has no local resources that cannot be migrated. For example,
  PCI or USB devices that are passed through currently block live-migration.
  Local Disks, on the other hand, can be migrated by sending them to the target
  just fine.
The hosts are located in the same Proxmox VE cluster.
The hosts have a working (and reliable) network connection between them.
The target host must have the same, or higher versions of the
  Proxmox VE packages. Although it can sometimes work the other way around, this
  cannot be guaranteed.
The hosts have CPUs from the same vendor with similar capabilities. Different
  vendor  might work depending on the actual models and VMs CPU type
  configured, but it cannot be guaranteed - so please test before deploying
  such a setup in production.
Offline Migration
If you have local resources, you can still migrate your VMs offline as long as
all disk are on storage defined on both hosts.
Migration then copies the disks to the target host over the network, as with
online migration. Note that any hardware pass-through configuration may need to
be adapted to the device location on the target host.
Copies and Clones
VM installation is usually done using an installation media (CD-ROM)
from the operating system vendor. Depending on the OS, this can be a
time consuming task one might want to avoid.
An easy way to deploy many VMs of the same type is to copy an existing
VM. We use the term clone for such copies, and distinguish between
linked and full clones.
Full Clone
The result of such copy is an independent VM. The
new VM does not share any storage resources with the original.
It is possible to select a Target Storage, so one can use this to
migrate a VM to a totally different storage. You can also change the
disk image Format if the storage driver supports several formats.
A full clone needs to read and copy all VM image data. This is
usually much slower than creating a linked clone.
Some storage types allows to copy a specific Snapshot, which
defaults to the current VM data. This also means that the final copy
never includes any additional snapshots from the original VM.
Linked Clone
Modern storage drivers support a way to generate fast linked
clones. Such a clone is a writable copy whose initial contents are the
same as the original data. Creating a linked clone is nearly
instantaneous, and initially consumes no additional space.
They are called linked because the new image still refers to the
original. Unmodified data blocks are read from the original image, but
modification are written (and afterwards read) from a new
location. This technique is called Copy-on-write.
This requires that the original volume is read-only. With Proxmox VE one
can convert any VM into a read-only  Template). Such
templates can later be used to create linked clones efficiently.
You cannot delete an original template while linked clones
exist.
It is not possible to change the Target storage for linked clones,
because this is a storage internal feature.
The Target node option allows you to create the new VM on a
different node. The only restriction is that the VM is on shared
storage, and that storage is also available on the target node.
To avoid resource conflicts, all network interface MAC addresses get
randomized, and we generate a new UUID for the VM BIOS (smbios1)
setting.
Virtual Machine Templates
One can convert a VM into a Template. Such templates are read-only,
and you can use them to create linked clones.
It is not possible to start templates, because this would modify
the disk images. If you want to change the template, create a linked
clone and modify that.
VM Generation ID
Proxmox VE supports Virtual Machine Generation ID (vmgenid) [Official
vmgenid Specification
https://docs.microsoft.com/en-us/windows/desktop/hyperv_v2/virtual-machine-generation-identifier]
for virtual machines.
This can be used by the guest operating system to detect any event resulting
in a time shift event, for example, restoring a backup or a snapshot rollback.
When creating new VMs, a vmgenid will be automatically generated and saved
in its configuration file.
To create and add a vmgenid to an already existing VM one can pass the
special value &#8216;1&#8217; to let Proxmox VE autogenerate one or manually set the UUID
[Online GUID generator http://guid.one/] by using it as value, for
example:
# qm set VMID -vmgenid 1
# qm set VMID -vmgenid 00000000-0000-0000-0000-000000000000
The initial addition of a vmgenid device to an existing VM, may result
in the same effects as a change on snapshot rollback, backup restore, etc., has
as the VM can interpret this as generation change.
In the rare case the vmgenid mechanism is not wanted one can pass &#8216;0&#8217; for
its value on VM creation, or retroactively delete the property in the
configuration with:
# qm set VMID -delete vmgenid
The most prominent use case for vmgenid are newer Microsoft Windows
operating systems, which use it to avoid problems in time sensitive or
replicate services (such as databases or domain controller
[https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/get-started/virtual-dc/virtualized-domain-controller-architecture])
on snapshot rollback, backup restore or a whole VM clone operation.
Importing Virtual Machines and disk images
A VM export from a foreign hypervisor takes usually the form of one or more disk
 images, with a configuration file describing the settings of the VM (RAM,
 number of cores).
The disk images can be in the vmdk format, if the disks come from
VMware or VirtualBox, or qcow2 if the disks come from a KVM hypervisor.
The most popular configuration format for VM exports is the OVF standard, but in
practice interoperation is limited because many settings are not implemented in
the standard itself, and hypervisors export the supplementary information
in non-standard extensions.
Besides the problem of format, importing disk images from other hypervisors
may fail if the emulated hardware changes too much from one hypervisor to
another. Windows VMs are particularly concerned by this, as the OS is very
picky about any changes of hardware. This problem may be solved by
installing the MergeIDE.zip utility available from the Internet before exporting
and choosing a hard disk type of IDE before booting the imported Windows VM.
Finally there is the question of paravirtualized drivers, which improve the
speed of the emulated system and are specific to the hypervisor.
GNU/Linux and other free Unix OSes have all the necessary drivers installed by
default and you can switch to the paravirtualized drivers right after importing
the VM. For Windows VMs, you need to install the Windows paravirtualized
drivers by yourself.
GNU/Linux and other free Unix can usually be imported without hassle. Note
that we cannot guarantee a successful import/export of Windows VMs in all
cases due to the problems above.
Step-by-step example of a Windows OVF import
Microsoft provides
Virtual Machines downloads
 to get started with Windows development.We are going to use one of these
to demonstrate the OVF import feature.
Download the Virtual Machine zip
After getting informed about the user agreement, choose the Windows 10
Enterprise (Evaluation - Build) for the VMware platform, and download the zip.
Extract the disk image from the zip
Using the unzip utility or any archiver of your choice, unpack the zip,
and copy via ssh/scp the ovf and vmdk files to your Proxmox VE host.
Import the Virtual Machine
This will create a new virtual machine, using cores, memory and
VM name as read from the OVF manifest, and import the disks to the local-lvm
 storage. You have to configure the network manually.
# qm importovf 999 WinDev1709Eval.ovf local-lvm
The VM is ready to be started.
Adding an external disk image to a Virtual Machine
You can also add an existing disk image to a VM, either coming from a
foreign hypervisor, or one that you created yourself.
Suppose you created a Debian/Ubuntu disk image with the vmdebootstrap tool:
vmdebootstrap --verbose \
 --size 10GiB --serial-console \
 --grub --no-extlinux \
 --package openssh-server \
 --package avahi-daemon \
 --package qemu-guest-agent \
 --hostname vm600 --enable-dhcp \
 --customize=./copy_pub_ssh.sh \
 --sparse --image vm600.raw
You can now create a new target VM, importing the image to the storage pvedir
and attaching it to the VM&#8217;s SCSI controller:
# qm create 600 --net0 virtio,bridge=vmbr0 --name vm600 --serial0 socket \
   --boot order=scsi0 --scsihw virtio-scsi-pci --ostype l26 \
   --scsi0 pvedir:0,import-from=/path/to/dir/vm600.raw
The VM is ready to be started.
Hookscripts
You can add a hook script to VMs with the config property hookscript.
# qm set 100 --hookscript local:snippets/hookscript.pl
It will be called during various phases of the guests lifetime.
For an example and documentation see the example script under
/usr/share/pve-docs/examples/guest-example-hookscript.pl.
Hibernation
You can suspend a VM to disk with the GUI option Hibernate or with
# qm suspend ID --todisk
That means that the current content of the memory will be saved onto disk
and the VM gets stopped. On the next start, the memory content will be
loaded and the VM can continue where it was left off.
State storage selection
If no target storage for the memory is given, it will be automatically
chosen, the first of:
The storage vmstatestorage from the VM config.
The first shared storage from any VM disk.
The first non-shared storage from any VM disk.
The storage local as a fallback.
Managing Virtual Machines with qm
qm is the tool to manage Qemu/Kvm virtual machines on Proxmox VE. You can
create and destroy virtual machines, and control execution
(start/stop/suspend/resume). Besides that, you can use qm to set
parameters in the associated config file. It is also possible to
create and delete virtual disks.
CLI Usage Examples
Using an iso file uploaded on the local storage, create a VM
with a 4 GB IDE disk on the local-lvm storage
# qm create 300 -ide0 local-lvm:4 -net0 e1000 -cdrom local:iso/proxmox-mailgateway_2.1.iso
Start the new VM
# qm start 300
Send a shutdown request, then wait until the VM is stopped.
# qm shutdown 300 &amp;&amp; qm wait 300
Same as above, but only wait for 40 seconds.
# qm shutdown 300 &amp;&amp; qm wait 300 -timeout 40
Destroying a VM always removes it from Access Control Lists and it always
removes the firewall configuration of the VM. You have to activate
--purge, if you want to additionally remove the VM from replication jobs,
backup jobs and HA resource configurations.
# qm destroy 300 --purge
Move a disk image to a different storage.
# qm move-disk 300 scsi0 other-storage
Reassign a disk image to a different VM. This will remove the disk scsi1 from
the source VM and attaches it as scsi3 to the target VM. In the background
the disk image is being renamed so that the name matches the new owner.
# qm move-disk 300 scsi1 --target-vmid 400 --target-disk scsi3
Configuration
VM configuration files are stored inside the Proxmox cluster file
system, and can be accessed at /etc/pve/qemu-server/&lt;VMID&gt;.conf.
Like other files stored inside /etc/pve/, they get automatically
replicated to all other cluster nodes.
VMIDs &lt; 100 are reserved for internal purposes, and VMIDs need to be
unique cluster wide.
Example VM Configuration
boot: order=virtio0;net0
cores: 1
sockets: 1
memory: 512
name: webmail
ostype: l26
net0: e1000=EE:D2:28:5F:B6:3E,bridge=vmbr0
virtio0: local:vm-100-disk-1,size=32G
Those configuration files are simple text files, and you can edit them
using a normal text editor (vi, nano, &#8230;). This is sometimes
useful to do small corrections, but keep in mind that you need to
restart the VM to apply such changes.
For that reason, it is usually better to use the qm command to
generate and modify those files, or do the whole thing using the GUI.
Our toolkit is smart enough to instantaneously apply most changes to
running VM. This feature is called "hot plug", and there is no
need to restart the VM in that case.
File Format
VM configuration files use a simple colon separated key/value
format. Each line has the following format:
# this is a comment
OPTION: value
Blank lines in those files are ignored, and lines starting with a #
character are treated as comments and are also ignored.
Snapshots
When you create a snapshot, qm stores the configuration at snapshot
time into a separate snapshot section within the same configuration
file. For example, after creating a snapshot called &#8220;testsnapshot&#8221;,
your configuration file will look like this:
VM configuration with snapshot
memory: 512
swap: 512
parent: testsnaphot
...
[testsnaphot]
memory: 512
swap: 512
snaptime: 1457170803
...
There are a few snapshot related properties like parent and
snaptime. The parent property is used to store the parent/child
relationship between snapshots. snaptime is the snapshot creation
time stamp (Unix epoch).
You can optionally save the memory of a running VM with the option vmstate.
For details about how the target storage gets chosen for the VM state, see
State storage selection in the chapter
Hibernation.
Options
acpi: &lt;boolean&gt; (default = 1)
Enable/disable ACPI.
affinity: &lt;string&gt;
List of host cores used to execute guest processes, for example: 0,5,8-11
agent: [enabled=]&lt;1|0&gt; [,fstrim_cloned_disks=&lt;1|0&gt;] [,type=&lt;virtio|isa&gt;]
Enable/disable communication with the Qemu Guest Agent and its properties.
enabled=&lt;boolean&gt; (default = 0)
Enable/disable communication with a Qemu Guest Agent (QGA) running in the VM.
fstrim_cloned_disks=&lt;boolean&gt; (default = 0)
Run fstrim after moving a disk or migrating the VM.
type=&lt;isa | virtio&gt; (default = virtio)
Select the agent type
arch: &lt;aarch64 | x86_64&gt;
Virtual processor architecture. Defaults to the host.
args: &lt;string&gt;
Arbitrary arguments passed to kvm, for example:
args: -no-reboot -no-hpet
this option is for experts only.
audio0: device=&lt;ich9-intel-hda|intel-hda|AC97&gt; [,driver=&lt;spice|none&gt;]
Configure a audio device, useful in combination with QXL/Spice.
device=&lt;AC97 | ich9-intel-hda | intel-hda&gt;
Configure an audio device.
driver=&lt;none | spice&gt; (default = spice)
Driver backend for the audio device.
autostart: &lt;boolean&gt; (default = 0)
Automatic restart after crash (currently ignored).
balloon: &lt;integer&gt; (0 - N)
Amount of target RAM for the VM in MB. Using zero disables the ballon driver.
bios: &lt;ovmf | seabios&gt; (default = seabios)
Select BIOS implementation.
boot: [[legacy=]&lt;[acdn]{1,4}&gt;] [,order=&lt;device[;device...]&gt;]
Specify guest boot order. Use the order= sub-property as usage with no key or legacy= is deprecated.
legacy=&lt;[acdn]{1,4}&gt; (default = cdn)
Boot on floppy (a), hard disk (c), CD-ROM (d), or network (n). Deprecated, use order= instead.
order=&lt;device[;device...]&gt;
The guest will attempt to boot from devices in the order they appear here.
Disks, optical drives and passed-through storage USB devices will be directly
booted from, NICs will load PXE, and PCIe devices will either behave like disks
(e.g. NVMe) or load an option ROM (e.g. RAID controller, hardware NIC).
Note that only devices in this list will be marked as bootable and thus loaded
by the guest firmware (BIOS/UEFI). If you require multiple disks for booting
(e.g. software-raid), you need to specify all of them here.
Overrides the deprecated legacy=[acdn]* value when given.
bootdisk: (ide|sata|scsi|virtio)\d+
Enable booting from specified disk. Deprecated: Use boot: order=foo;bar instead.
cdrom: &lt;volume&gt;
This is an alias for option -ide2
cicustom: [meta=&lt;volume&gt;] [,network=&lt;volume&gt;] [,user=&lt;volume&gt;] [,vendor=&lt;volume&gt;]
cloud-init: Specify custom files to replace the automatically generated ones at start.
meta=&lt;volume&gt;
Specify a custom file containing all meta data passed to the VM via"
            ." cloud-init. This is provider specific meaning configdrive2 and nocloud differ.
network=&lt;volume&gt;
Specify a custom file containing all network data passed to the VM via cloud-init.
user=&lt;volume&gt;
Specify a custom file containing all user data passed to the VM via cloud-init.
vendor=&lt;volume&gt;
Specify a custom file containing all vendor data passed to the VM via cloud-init.
cipassword: &lt;string&gt;
cloud-init: Password to assign the user. Using this is generally not recommended. Use ssh keys instead. Also note that older cloud-init versions do not support hashed passwords.
citype: &lt;configdrive2 | nocloud | opennebula&gt;
Specifies the cloud-init configuration format. The default depends on the configured operating system type (ostype. We use the nocloud format for Linux, and configdrive2 for windows.
ciuser: &lt;string&gt;
cloud-init: User name to change ssh keys and password for instead of the image&#8217;s configured default user.
cores: &lt;integer&gt; (1 - N) (default = 1)
The number of cores per socket.
cpu: [[cputype=]&lt;string&gt;] [,flags=&lt;+FLAG[;-FLAG...]&gt;] [,hidden=&lt;1|0&gt;] [,hv-vendor-id=&lt;vendor-id&gt;] [,phys-bits=&lt;8-64|host&gt;] [,reported-model=&lt;enum&gt;]
Emulated CPU type.
cputype=&lt;string&gt; (default = kvm64)
Emulated CPU type. Can be default or custom name (custom model names must be prefixed with custom-).
flags=&lt;+FLAG[;-FLAG...]&gt;
List of additional CPU flags separated by ;. Use +FLAG to enable, -FLAG to disable a flag. Custom CPU models can specify any flag supported by QEMU/KVM, VM-specific flags must be from the following set for security reasons: pcid, spec-ctrl, ibpb, ssbd, virt-ssbd, amd-ssbd, amd-no-ssb, pdpe1gb, md-clear, hv-tlbflush, hv-evmcs, aes
hidden=&lt;boolean&gt; (default = 0)
Do not identify as a KVM virtual machine.
hv-vendor-id=&lt;vendor-id&gt;
The Hyper-V vendor ID. Some drivers or programs inside Windows guests need a specific ID.
phys-bits=&lt;8-64|host&gt;
The physical memory address bits that are reported to the guest OS. Should be smaller or equal to the host&#8217;s. Set to host to use value from host CPU, but note that doing so will break live migration to CPUs with other values.
reported-model=&lt;486 | Broadwell | Broadwell-IBRS | Broadwell-noTSX | Broadwell-noTSX-IBRS | Cascadelake-Server | Cascadelake-Server-noTSX | Conroe | EPYC | EPYC-IBPB | EPYC-Milan | EPYC-Rome | Haswell | Haswell-IBRS | Haswell-noTSX | Haswell-noTSX-IBRS | Icelake-Client | Icelake-Client-noTSX | Icelake-Server | Icelake-Server-noTSX | IvyBridge | IvyBridge-IBRS | KnightsMill | Nehalem | Nehalem-IBRS | Opteron_G1 | Opteron_G2 | Opteron_G3 | Opteron_G4 | Opteron_G5 | Penryn | SandyBridge | SandyBridge-IBRS | Skylake-Client | Skylake-Client-IBRS | Skylake-Client-noTSX-IBRS | Skylake-Server | Skylake-Server-IBRS | Skylake-Server-noTSX-IBRS | Westmere | Westmere-IBRS | athlon | core2duo | coreduo | host | kvm32 | kvm64 | max | pentium | pentium2 | pentium3 | phenom | qemu32 | qemu64&gt; (default = kvm64)
CPU model and vendor to report to the guest. Must be a QEMU/KVM supported model. Only valid for custom CPU model definitions, default models will always report themselves to the guest OS.
cpulimit: &lt;number&gt; (0 - 128) (default = 0)
Limit of CPU usage.
If the computer has 2 CPUs, it has total of 2 CPU time. Value 0 indicates no CPU limit.
cpuunits: &lt;integer&gt; (1 - 262144) (default = cgroup v1: 1024, cgroup v2: 100)
CPU weight for a VM. Argument is used in the kernel fair scheduler. The larger the number is, the more CPU time this VM gets. Number is relative to weights of all the other running VMs.
description: &lt;string&gt;
Description for the VM. Shown in the web-interface VM&#8217;s summary. This is saved as comment inside the configuration file.
efidisk0: [file=]&lt;volume&gt; [,efitype=&lt;2m|4m&gt;] [,format=&lt;enum&gt;] [,pre-enrolled-keys=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;]
Configure a Disk for storing EFI vars.
efitype=&lt;2m | 4m&gt; (default = 2m)
Size and type of the OVMF EFI vars. 4m is newer and recommended, and required for Secure Boot. For backwards compatibility, 2m is used if not otherwise specified.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
pre-enrolled-keys=&lt;boolean&gt; (default = 0)
Use am EFI vars template with distribution-specific and Microsoft Standard keys enrolled, if used with efitype=4m. Note that this will enable Secure Boot by default, though it can still be turned off from within the VM.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
freeze: &lt;boolean&gt;
Freeze CPU at startup (use c monitor command to start execution).
hookscript: &lt;string&gt;
Script that will be executed during various steps in the vms lifetime.
hostpci[n]: [host=]&lt;HOSTPCIID[;HOSTPCIID2...]&gt; [,device-id=&lt;hex id&gt;] [,legacy-igd=&lt;1|0&gt;] [,mdev=&lt;string&gt;] [,pcie=&lt;1|0&gt;] [,rombar=&lt;1|0&gt;] [,romfile=&lt;string&gt;] [,sub-device-id=&lt;hex id&gt;] [,sub-vendor-id=&lt;hex id&gt;] [,vendor-id=&lt;hex id&gt;] [,x-vga=&lt;1|0&gt;]
Map host PCI devices into guest.
This option allows direct access to host hardware. So it is no longer
possible to migrate such machines - use with special care.
Experimental! User reported problems with this option.
device-id=&lt;hex id&gt;
Override PCI device ID visible to guest
host=&lt;HOSTPCIID[;HOSTPCIID2...]&gt;
Host PCI device pass through. The PCI ID of a host&#8217;s PCI device or a list
of PCI virtual functions of the host. HOSTPCIID syntax is:
bus:dev.func (hexadecimal numbers)
You can us the lspci command to list existing PCI devices.
legacy-igd=&lt;boolean&gt; (default = 0)
Pass this device in legacy IGD mode, making it the primary and exclusive graphics device in the VM. Requires pc-i440fx machine type and VGA set to none.
mdev=&lt;string&gt;
The type of mediated device to use.
An instance of this type will be created on startup of the VM and
will be cleaned up when the VM stops.
pcie=&lt;boolean&gt; (default = 0)
Choose the PCI-express bus (needs the q35 machine model).
rombar=&lt;boolean&gt; (default = 1)
Specify whether or not the device&#8217;s ROM will be visible in the guest&#8217;s memory map.
romfile=&lt;string&gt;
Custom pci device rom filename (must be located in /usr/share/kvm/).
sub-device-id=&lt;hex id&gt;
Override PCI subsystem device ID visible to guest
sub-vendor-id=&lt;hex id&gt;
Override PCI subsystem vendor ID visible to guest
vendor-id=&lt;hex id&gt;
Override PCI vendor ID visible to guest
x-vga=&lt;boolean&gt; (default = 0)
Enable vfio-vga device support.
hotplug: &lt;string&gt; (default = network,disk,usb)
Selectively enable hotplug features. This is a comma separated list of hotplug features: network, disk, cpu, memory, usb and cloudinit. Use 0 to disable hotplug completely. Using 1 as value is an alias for the default network,disk,usb. USB hotplugging is possible for guests with machine version &gt;= 7.1 and ostype l26 or windows &gt; 7.
hugepages: &lt;1024 | 2 | any&gt;
Enable/disable hugepages memory.
ide[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads|io_uring&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_max_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_max_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_rd_max_length=&lt;seconds&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_max=&lt;iops&gt;] [,iops_wr_max_length=&lt;seconds&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,model=&lt;model&gt;] [,replicate=&lt;1|0&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,ssd=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;] [,wwn=&lt;wwn&gt;]
Use volume as IDE hard disk or CD-ROM (n is 0 to 3).
aio=&lt;io_uring | native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iops_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
model=&lt;model&gt;
The drive&#8217;s reported model name, url-encoded, up to 40 bytes long.
replicate=&lt;boolean&gt; (default = 1)
Whether the drive should considered for replication jobs.
rerror=&lt;ignore | report | stop&gt;
Read error action.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
shared=&lt;boolean&gt; (default = 0)
Mark this locally-managed volume as available on all nodes.
This option does not share the volume automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Controls qemu&#8217;s snapshot mode feature. If activated, changes made to the disk are temporary and will be discarded when the VM is shutdown.
ssd=&lt;boolean&gt;
Whether to expose this drive as an SSD, rather than a rotational hard disk.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
wwn=&lt;wwn&gt;
The drive&#8217;s worldwide name, encoded as 16 bytes hex string, prefixed by 0x.
ipconfig[n]: [gw=&lt;GatewayIPv4&gt;] [,gw6=&lt;GatewayIPv6&gt;] [,ip=&lt;IPv4Format/CIDR&gt;] [,ip6=&lt;IPv6Format/CIDR&gt;]
cloud-init: Specify IP addresses and gateways for the corresponding interface.
IP addresses use CIDR notation, gateways are optional but need an IP of the same type specified.
The special string dhcp can be used for IP addresses to use DHCP, in which case no explicit
gateway should be provided.
For IPv6 the special string auto can be used to use stateless autoconfiguration. This requires
cloud-init 19.4 or newer.
If cloud-init is enabled and neither an IPv4 nor an IPv6 address is specified, it defaults to using
dhcp on IPv4.
gw=&lt;GatewayIPv4&gt;
Default gateway for IPv4 traffic.
Requires option(s): ip
gw6=&lt;GatewayIPv6&gt;
Default gateway for IPv6 traffic.
Requires option(s): ip6
ip=&lt;IPv4Format/CIDR&gt; (default = dhcp)
IPv4 address in CIDR format.
ip6=&lt;IPv6Format/CIDR&gt; (default = dhcp)
IPv6 address in CIDR format.
ivshmem: size=&lt;integer&gt; [,name=&lt;string&gt;]
Inter-VM shared memory. Useful for direct communication between VMs, or to the host.
name=&lt;string&gt;
The name of the file. Will be prefixed with pve-shm-. Default is the VMID. Will be deleted when the VM is stopped.
size=&lt;integer&gt; (1 - N)
The size of the file in MB.
keephugepages: &lt;boolean&gt; (default = 0)
Use together with hugepages. If enabled, hugepages will not not be deleted after VM shutdown and can be used for subsequent starts.
keyboard: &lt;da | de | de-ch | en-gb | en-us | es | fi | fr | fr-be | fr-ca | fr-ch | hu | is | it | ja | lt | mk | nl | no | pl | pt | pt-br | sl | sv | tr&gt;
Keyboard layout for VNC server. This option is generally not required and is often better handled from within the guest OS.
kvm: &lt;boolean&gt; (default = 1)
Enable/disable KVM hardware virtualization.
localtime: &lt;boolean&gt;
Set the real time clock (RTC) to local time. This is enabled by default if the ostype indicates a Microsoft Windows OS.
lock: &lt;backup | clone | create | migrate | rollback | snapshot | snapshot-delete | suspended | suspending&gt;
Lock/unlock the VM.
machine: (pc|pc(-i440fx)?-\d+(\.\d+)+(\+pve\d+)?(\.pxe)?|q35|pc-q35-\d+(\.\d+)+(\+pve\d+)?(\.pxe)?|virt(?:-\d+(\.\d+)+)?(\+pve\d+)?)
Specifies the Qemu machine type.
memory: &lt;integer&gt; (16 - N) (default = 512)
Amount of RAM for the VM in MB. This is the maximum available memory when you use the balloon device.
migrate_downtime: &lt;number&gt; (0 - N) (default = 0.1)
Set maximum tolerated downtime (in seconds) for migrations.
migrate_speed: &lt;integer&gt; (0 - N) (default = 0)
Set maximum speed (in MB/s) for migrations. Value 0 is no limit.
name: &lt;string&gt;
Set a name for the VM. Only used on the configuration web interface.
nameserver: &lt;string&gt;
cloud-init: Sets DNS server IP address for a container. Create will automatically use the setting from the host if neither searchdomain nor nameserver are set.
net[n]: [model=]&lt;enum&gt; [,bridge=&lt;bridge&gt;] [,firewall=&lt;1|0&gt;] [,link_down=&lt;1|0&gt;] [,macaddr=&lt;XX:XX:XX:XX:XX:XX&gt;] [,mtu=&lt;integer&gt;] [,queues=&lt;integer&gt;] [,rate=&lt;number&gt;] [,tag=&lt;integer&gt;] [,trunks=&lt;vlanid[;vlanid...]&gt;] [,&lt;model&gt;=&lt;macaddr&gt;]
Specify network devices.
bridge=&lt;bridge&gt;
Bridge to attach the network device to. The Proxmox VE standard bridge
is called vmbr0.
If you do not specify a bridge, we create a kvm user (NATed) network
device, which provides DHCP and DNS services. The following addresses
are used:
10.0.2.2   Gateway
10.0.2.3   DNS Server
10.0.2.4   SMB Server
The DHCP server assign addresses to the guest starting from 10.0.2.15.
firewall=&lt;boolean&gt;
Whether this interface should be protected by the firewall.
link_down=&lt;boolean&gt;
Whether this interface should be disconnected (like pulling the plug).
macaddr=&lt;XX:XX:XX:XX:XX:XX&gt;
A common MAC address with the I/G (Individual/Group) bit not set.
model=&lt;e1000 | e1000-82540em | e1000-82544gc | e1000-82545em | e1000e | i82551 | i82557b | i82559er | ne2k_isa | ne2k_pci | pcnet | rtl8139 | virtio | vmxnet3&gt;
Network Card Model. The virtio model provides the best performance with very low CPU overhead. If your guest does not support this driver, it is usually best to use e1000.
mtu=&lt;integer&gt; (1 - 65520)
Force MTU, for VirtIO only. Set to 1 to use the bridge MTU
queues=&lt;integer&gt; (0 - 64)
Number of packet queues to be used on the device.
rate=&lt;number&gt; (0 - N)
Rate limit in mbps (megabytes per second) as floating point number.
tag=&lt;integer&gt; (1 - 4094)
VLAN tag to apply to packets on this interface.
trunks=&lt;vlanid[;vlanid...]&gt;
VLAN trunks to pass through this interface.
numa: &lt;boolean&gt; (default = 0)
Enable/disable NUMA.
numa[n]: cpus=&lt;id[-id];...&gt; [,hostnodes=&lt;id[-id];...&gt;] [,memory=&lt;number&gt;] [,policy=&lt;preferred|bind|interleave&gt;]
NUMA topology.
cpus=&lt;id[-id];...&gt;
CPUs accessing this NUMA node.
hostnodes=&lt;id[-id];...&gt;
Host NUMA nodes to use.
memory=&lt;number&gt;
Amount of memory this NUMA node provides.
policy=&lt;bind | interleave | preferred&gt;
NUMA allocation policy.
onboot: &lt;boolean&gt; (default = 0)
Specifies whether a VM will be started during system bootup.
ostype: &lt;l24 | l26 | other | solaris | w2k | w2k3 | w2k8 | win10 | win11 | win7 | win8 | wvista | wxp&gt;
Specify guest operating system. This is used to enable special
optimization/features for specific operating systems:
other
unspecified OS
wxp
Microsoft Windows XP
w2k
Microsoft Windows 2000
w2k3
Microsoft Windows 2003
w2k8
Microsoft Windows 2008
wvista
Microsoft Windows Vista
win7
Microsoft Windows 7
win8
Microsoft Windows 8/2012/2012r2
win10
Microsoft Windows 10/2016/2019
win11
Microsoft Windows 11/2022
l24
Linux 2.4 Kernel
l26
Linux 2.6 - 5.X Kernel
solaris
Solaris/OpenSolaris/OpenIndiania kernel
parallel[n]: /dev/parport\d+|/dev/usb/lp\d+
Map host parallel devices (n is 0 to 2).
This option allows direct access to host hardware. So it is no longer possible to migrate such
machines - use with special care.
Experimental! User reported problems with this option.
protection: &lt;boolean&gt; (default = 0)
Sets the protection flag of the VM. This will disable the remove VM and remove disk operations.
reboot: &lt;boolean&gt; (default = 1)
Allow reboot. If set to 0 the VM exit on reboot.
rng0: [source=]&lt;/dev/urandom|/dev/random|/dev/hwrng&gt; [,max_bytes=&lt;integer&gt;] [,period=&lt;integer&gt;]
Configure a VirtIO-based Random Number Generator.
max_bytes=&lt;integer&gt; (default = 1024)
Maximum bytes of entropy allowed to get injected into the guest every period milliseconds. Prefer a lower value when using /dev/random as source. Use 0 to disable limiting (potentially dangerous!).
period=&lt;integer&gt; (default = 1000)
Every period milliseconds the entropy-injection quota is reset, allowing the guest to retrieve another max_bytes of entropy.
source=&lt;/dev/hwrng | /dev/random | /dev/urandom&gt;
The file on the host to gather entropy from. In most cases /dev/urandom should be preferred over /dev/random to avoid entropy-starvation issues on the host. Using urandom does not decrease security in any meaningful way, as it&#8217;s still seeded from real entropy, and the bytes provided will most likely be mixed with real entropy on the guest as well. /dev/hwrng can be used to pass through a hardware RNG from the host.
sata[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads|io_uring&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_max_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_max_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_rd_max_length=&lt;seconds&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_max=&lt;iops&gt;] [,iops_wr_max_length=&lt;seconds&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,replicate=&lt;1|0&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,ssd=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;] [,wwn=&lt;wwn&gt;]
Use volume as SATA hard disk or CD-ROM (n is 0 to 5).
aio=&lt;io_uring | native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iops_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
replicate=&lt;boolean&gt; (default = 1)
Whether the drive should considered for replication jobs.
rerror=&lt;ignore | report | stop&gt;
Read error action.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
shared=&lt;boolean&gt; (default = 0)
Mark this locally-managed volume as available on all nodes.
This option does not share the volume automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Controls qemu&#8217;s snapshot mode feature. If activated, changes made to the disk are temporary and will be discarded when the VM is shutdown.
ssd=&lt;boolean&gt;
Whether to expose this drive as an SSD, rather than a rotational hard disk.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
wwn=&lt;wwn&gt;
The drive&#8217;s worldwide name, encoded as 16 bytes hex string, prefixed by 0x.
scsi[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads|io_uring&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_max_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_max_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_rd_max_length=&lt;seconds&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_max=&lt;iops&gt;] [,iops_wr_max_length=&lt;seconds&gt;] [,iothread=&lt;1|0&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,queues=&lt;integer&gt;] [,replicate=&lt;1|0&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,ro=&lt;1|0&gt;] [,scsiblock=&lt;1|0&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,ssd=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;] [,wwn=&lt;wwn&gt;]
Use volume as SCSI hard disk or CD-ROM (n is 0 to 30).
aio=&lt;io_uring | native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iops_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iothread=&lt;boolean&gt;
Whether to use iothreads for this drive
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
queues=&lt;integer&gt; (2 - N)
Number of queues.
replicate=&lt;boolean&gt; (default = 1)
Whether the drive should considered for replication jobs.
rerror=&lt;ignore | report | stop&gt;
Read error action.
ro=&lt;boolean&gt;
Whether the drive is read-only.
scsiblock=&lt;boolean&gt; (default = 0)
whether to use scsi-block for full passthrough of host block device
can lead to I/O errors in combination with low memory or high memory fragmentation on host
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
shared=&lt;boolean&gt; (default = 0)
Mark this locally-managed volume as available on all nodes.
This option does not share the volume automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Controls qemu&#8217;s snapshot mode feature. If activated, changes made to the disk are temporary and will be discarded when the VM is shutdown.
ssd=&lt;boolean&gt;
Whether to expose this drive as an SSD, rather than a rotational hard disk.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
wwn=&lt;wwn&gt;
The drive&#8217;s worldwide name, encoded as 16 bytes hex string, prefixed by 0x.
scsihw: &lt;lsi | lsi53c810 | megasas | pvscsi | virtio-scsi-pci | virtio-scsi-single&gt; (default = lsi)
SCSI controller model
searchdomain: &lt;string&gt;
cloud-init: Sets DNS search domains for a container. Create will automatically use the setting from the host if neither searchdomain nor nameserver are set.
serial[n]: (/dev/.+|socket)
Create a serial device inside the VM (n is 0 to 3), and pass through a
host serial device (i.e. /dev/ttyS0), or create a unix socket on the
host side (use qm terminal to open a terminal connection).
If you pass through a host serial device, it is no longer possible to migrate such machines -
use with special care.
Experimental! User reported problems with this option.
shares: &lt;integer&gt; (0 - 50000) (default = 1000)
Amount of memory shares for auto-ballooning. The larger the number is, the more memory this VM gets. Number is relative to weights of all other running VMs. Using zero disables auto-ballooning. Auto-ballooning is done by pvestatd.
smbios1: [base64=&lt;1|0&gt;] [,family=&lt;Base64 encoded string&gt;] [,manufacturer=&lt;Base64 encoded string&gt;] [,product=&lt;Base64 encoded string&gt;] [,serial=&lt;Base64 encoded string&gt;] [,sku=&lt;Base64 encoded string&gt;] [,uuid=&lt;UUID&gt;] [,version=&lt;Base64 encoded string&gt;]
Specify SMBIOS type 1 fields.
base64=&lt;boolean&gt;
Flag to indicate that the SMBIOS values are base64 encoded
family=&lt;Base64 encoded string&gt;
Set SMBIOS1 family string.
manufacturer=&lt;Base64 encoded string&gt;
Set SMBIOS1 manufacturer.
product=&lt;Base64 encoded string&gt;
Set SMBIOS1 product ID.
serial=&lt;Base64 encoded string&gt;
Set SMBIOS1 serial number.
sku=&lt;Base64 encoded string&gt;
Set SMBIOS1 SKU string.
uuid=&lt;UUID&gt;
Set SMBIOS1 UUID.
version=&lt;Base64 encoded string&gt;
Set SMBIOS1 version.
smp: &lt;integer&gt; (1 - N) (default = 1)
The number of CPUs. Please use option -sockets instead.
sockets: &lt;integer&gt; (1 - N) (default = 1)
The number of CPU sockets.
spice_enhancements: [foldersharing=&lt;1|0&gt;] [,videostreaming=&lt;off|all|filter&gt;]
Configure additional enhancements for SPICE.
foldersharing=&lt;boolean&gt; (default = 0)
Enable folder sharing via SPICE. Needs Spice-WebDAV daemon installed in the VM.
videostreaming=&lt;all | filter | off&gt; (default = off)
Enable video streaming. Uses compression for detected video streams.
sshkeys: &lt;string&gt;
cloud-init: Setup public SSH keys (one key per line, OpenSSH format).
startdate: (now | YYYY-MM-DD | YYYY-MM-DDTHH:MM:SS) (default = now)
Set the initial date of the real time clock. Valid format for date are:'now' or 2006-06-17T16:01:21 or 2006-06-17.
startup: `[[order=]\d+] [,up=\d+] [,down=\d+] `
Startup and shutdown behavior. Order is a non-negative number defining the general startup order. Shutdown in done with reverse ordering. Additionally you can set the up or down delay in seconds, which specifies a delay to wait before the next VM is started or stopped.
tablet: &lt;boolean&gt; (default = 1)
Enable/disable the USB tablet device. This device is usually needed to allow absolute mouse positioning with VNC. Else the mouse runs out of sync with normal VNC clients. If you&#8217;re running lots of console-only guests on one host, you may consider disabling this to save some context switches. This is turned off by default if you use spice (qm set &lt;vmid&gt; --vga qxl).
tags: &lt;string&gt;
Tags of the VM. This is only meta information.
tdf: &lt;boolean&gt; (default = 0)
Enable/disable time drift fix.
template: &lt;boolean&gt; (default = 0)
Enable/disable Template.
tpmstate0: [file=]&lt;volume&gt; [,size=&lt;DiskSize&gt;] [,version=&lt;v1.2|v2.0&gt;]
Configure a Disk for storing TPM state. The format is fixed to raw.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
version=&lt;v1.2 | v2.0&gt; (default = v2.0)
The TPM interface version. v2.0 is newer and should be preferred. Note that this cannot be changed later on.
unused[n]: [file=]&lt;volume&gt;
Reference to unused volumes. This is used internally, and should not be modified manually.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
usb[n]: [host=]&lt;HOSTUSBDEVICE|spice&gt; [,usb3=&lt;1|0&gt;]
Configure an USB device (n is 0 to 4, for machine version &gt;= 7.1 and ostype l26 or windows &gt; 7, n can be up to 14).
host=&lt;HOSTUSBDEVICE|spice&gt;
The Host USB device or port or the value spice. HOSTUSBDEVICE syntax is:
'bus-port(.port)*' (decimal numbers) or
'vendor_id:product_id' (hexadeciaml numbers) or
'spice'
You can use the lsusb -t command to list existing usb devices.
This option allows direct access to host hardware. So it is no longer possible to migrate such
machines - use with special care.
The value spice can be used to add a usb redirection devices for spice.
usb3=&lt;boolean&gt; (default = 0)
Specifies whether if given host option is a USB3 device or port. For modern guests (machine version &gt;= 7.1 and ostype l26 and windows &gt; 7), this flag is irrelevant (all devices are plugged into a xhci controller).
vcpus: &lt;integer&gt; (1 - N) (default = 0)
Number of hotplugged vcpus.
vga: [[type=]&lt;enum&gt;] [,memory=&lt;integer&gt;]
Configure the VGA Hardware. If you want to use high resolution modes (&gt;= 1280x1024x16) you may need to increase the vga memory option. Since QEMU 2.9 the default VGA display type is std for all OS types besides some Windows versions (XP and older) which use cirrus. The qxl option enables the SPICE display server. For win* OS you can select how many independent displays you want, Linux guests can add displays them self.
You can also run without any graphic card, using a serial device as terminal.
memory=&lt;integer&gt; (4 - 512)
Sets the VGA memory (in MiB). Has no effect with serial display.
type=&lt;cirrus | none | qxl | qxl2 | qxl3 | qxl4 | serial0 | serial1 | serial2 | serial3 | std | virtio | virtio-gl | vmware&gt; (default = std)
Select the VGA type.
virtio[n]: [file=]&lt;volume&gt; [,aio=&lt;native|threads|io_uring&gt;] [,backup=&lt;1|0&gt;] [,bps=&lt;bps&gt;] [,bps_max_length=&lt;seconds&gt;] [,bps_rd=&lt;bps&gt;] [,bps_rd_max_length=&lt;seconds&gt;] [,bps_wr=&lt;bps&gt;] [,bps_wr_max_length=&lt;seconds&gt;] [,cache=&lt;enum&gt;] [,cyls=&lt;integer&gt;] [,detect_zeroes=&lt;1|0&gt;] [,discard=&lt;ignore|on&gt;] [,format=&lt;enum&gt;] [,heads=&lt;integer&gt;] [,iops=&lt;iops&gt;] [,iops_max=&lt;iops&gt;] [,iops_max_length=&lt;seconds&gt;] [,iops_rd=&lt;iops&gt;] [,iops_rd_max=&lt;iops&gt;] [,iops_rd_max_length=&lt;seconds&gt;] [,iops_wr=&lt;iops&gt;] [,iops_wr_max=&lt;iops&gt;] [,iops_wr_max_length=&lt;seconds&gt;] [,iothread=&lt;1|0&gt;] [,mbps=&lt;mbps&gt;] [,mbps_max=&lt;mbps&gt;] [,mbps_rd=&lt;mbps&gt;] [,mbps_rd_max=&lt;mbps&gt;] [,mbps_wr=&lt;mbps&gt;] [,mbps_wr_max=&lt;mbps&gt;] [,media=&lt;cdrom|disk&gt;] [,replicate=&lt;1|0&gt;] [,rerror=&lt;ignore|report|stop&gt;] [,ro=&lt;1|0&gt;] [,secs=&lt;integer&gt;] [,serial=&lt;serial&gt;] [,shared=&lt;1|0&gt;] [,size=&lt;DiskSize&gt;] [,snapshot=&lt;1|0&gt;] [,trans=&lt;none|lba|auto&gt;] [,werror=&lt;enum&gt;]
Use volume as VIRTIO hard disk (n is 0 to 15).
aio=&lt;io_uring | native | threads&gt;
AIO type to use.
backup=&lt;boolean&gt;
Whether the drive should be included when making backups.
bps=&lt;bps&gt;
Maximum r/w speed in bytes per second.
bps_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
bps_rd=&lt;bps&gt;
Maximum read speed in bytes per second.
bps_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
bps_wr=&lt;bps&gt;
Maximum write speed in bytes per second.
bps_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
cache=&lt;directsync | none | unsafe | writeback | writethrough&gt;
The drive&#8217;s cache mode
cyls=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific cylinder count.
detect_zeroes=&lt;boolean&gt;
Controls whether to detect and try to optimize writes of zeroes.
discard=&lt;ignore | on&gt;
Controls whether to pass discard/trim requests to the underlying storage.
file=&lt;volume&gt;
The drive&#8217;s backing volume.
format=&lt;cloop | cow | qcow | qcow2 | qed | raw | vmdk&gt;
The drive&#8217;s backing file&#8217;s data format.
heads=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific head count.
iops=&lt;iops&gt;
Maximum r/w I/O in operations per second.
iops_max=&lt;iops&gt;
Maximum unthrottled r/w I/O pool in operations per second.
iops_max_length=&lt;seconds&gt;
Maximum length of I/O bursts in seconds.
iops_rd=&lt;iops&gt;
Maximum read I/O in operations per second.
iops_rd_max=&lt;iops&gt;
Maximum unthrottled read I/O pool in operations per second.
iops_rd_max_length=&lt;seconds&gt;
Maximum length of read I/O bursts in seconds.
iops_wr=&lt;iops&gt;
Maximum write I/O in operations per second.
iops_wr_max=&lt;iops&gt;
Maximum unthrottled write I/O pool in operations per second.
iops_wr_max_length=&lt;seconds&gt;
Maximum length of write I/O bursts in seconds.
iothread=&lt;boolean&gt;
Whether to use iothreads for this drive
mbps=&lt;mbps&gt;
Maximum r/w speed in megabytes per second.
mbps_max=&lt;mbps&gt;
Maximum unthrottled r/w pool in megabytes per second.
mbps_rd=&lt;mbps&gt;
Maximum read speed in megabytes per second.
mbps_rd_max=&lt;mbps&gt;
Maximum unthrottled read pool in megabytes per second.
mbps_wr=&lt;mbps&gt;
Maximum write speed in megabytes per second.
mbps_wr_max=&lt;mbps&gt;
Maximum unthrottled write pool in megabytes per second.
media=&lt;cdrom | disk&gt; (default = disk)
The drive&#8217;s media type.
replicate=&lt;boolean&gt; (default = 1)
Whether the drive should considered for replication jobs.
rerror=&lt;ignore | report | stop&gt;
Read error action.
ro=&lt;boolean&gt;
Whether the drive is read-only.
secs=&lt;integer&gt;
Force the drive&#8217;s physical geometry to have a specific sector count.
serial=&lt;serial&gt;
The drive&#8217;s reported serial number, url-encoded, up to 20 bytes long.
shared=&lt;boolean&gt; (default = 0)
Mark this locally-managed volume as available on all nodes.
This option does not share the volume automatically, it assumes it is shared already!
size=&lt;DiskSize&gt;
Disk size. This is purely informational and has no effect.
snapshot=&lt;boolean&gt;
Controls qemu&#8217;s snapshot mode feature. If activated, changes made to the disk are temporary and will be discarded when the VM is shutdown.
trans=&lt;auto | lba | none&gt;
Force disk geometry bios translation mode.
werror=&lt;enospc | ignore | report | stop&gt;
Write error action.
vmgenid: &lt;UUID&gt; (default = 1 (autogenerated))
The VM generation ID (vmgenid) device exposes a 128-bit integer value identifier to the guest OS. This allows to notify the guest operating system when the virtual machine is executed with a different configuration (e.g. snapshot execution or creation from a template). The guest operating system notices the change, and is then able to react as appropriate by marking its copies of distributed databases as dirty, re-initializing its random number generator, etc.
Note that auto-creation only works when done through API/CLI create or update methods, but not when manually editing the config file.
vmstatestorage: &lt;string&gt;
Default storage for VM state volumes/files.
watchdog: [[model=]&lt;i6300esb|ib700&gt;] [,action=&lt;enum&gt;]
Create a virtual hardware watchdog device. Once enabled (by a guest action), the watchdog must be periodically polled by an agent inside the guest or else the watchdog will reset the guest (or execute the respective action specified)
action=&lt;debug | none | pause | poweroff | reset | shutdown&gt;
The action to perform if after activation the guest fails to poll the watchdog in time.
model=&lt;i6300esb | ib700&gt; (default = i6300esb)
Watchdog type to emulate.
Locks
Online migrations, snapshots and backups (vzdump) set a lock to prevent
incompatible concurrent actions on the affected VMs. Sometimes you need to
remove such a lock manually (for example after a power failure).
# qm unlock &lt;vmid&gt;
Only do that if you are sure the action which set the lock is
no longer running.
See Also
Cloud-Init Support
</pvehide>
<!--PVE_IMPORT_END_MARKER-->
```

## PCI Passthrough

```wiki
== Introduction ==

{{Note|This is a collection of examples, workarounds, hacks, and specific issues for PCI(e) passthrough. For a step-by-step guide on how and what to do to pass through PCI(e) devices, see [https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_pci_passthrough the docs] or  [[PCI(e)_Passthrough|the wiki page generated from the docs]]}}

PCI passthrough allows you to use a physical PCI device (graphics card, network card) inside a VM (KVM virtualization only).

If you "PCI passthrough" a device, the device is not available to the host anymore. Note that VMs with passed-through devices cannot be migrated.

== Requirements ==

This is a list of basic requirements adapted from [https://wiki.archlinux.org/title/PCI_passthrough_via_OVMF#Prerequisites the Arch wiki]

; CPU requirements:
: Your CPU has to support hardware virtualization and IOMMU. Most new CPUs support this.
* AMD: CPUs from the Bulldozer generation and newer, CPUs from the K10 generation need a 890FX or 990FX motherboard.
* Intel: [https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&0_VTD=True list of VT-d capable Intel CPUs]

; Motherboard requirements:
: Your motherboard needs to support IOMMU. Lists can be found on [https://wiki.xenproject.org/wiki/VTd_HowTo the Xen wiki] and [https://en.wikipedia.org/wiki/List_of_IOMMU-supporting_hardware Wikipedia]. Note that, as of writing, both these lists are incomplete and very out-of-date and most newer motherboards support IOMMU.

; GPU requirements:
: The ROM of your GPU does not necessarily need to support UEFI, however, most modern GPUs do. If you GPU ROM supports UEFI, it is recommended to use OVMF (UEFI) instead of SeaBIOS. For a list of GPU ROMs, see [https://www.techpowerup.com/vgabios/?architecture=&manufacturer=&model=&version=&interface=&memType=&memSize=&since= Techpowerup's collection of GPU ROMs]

== Verifying IOMMU parameters ==
=== Verify IOMMU is enabled ===

Reboot, then run:
 dmesg | grep -e DMAR -e IOMMU

There should be a line that looks like "DMAR: IOMMU enabled". If there is no output, something is wrong.

=== Verify IOMMU interrupt remapping is enabled ===

It is not possible to use PCI passthrough without interrupt remapping. Device assignment will fail with 'Failed to assign device "[device name]": Operation not permitted' or 'Interrupt Remapping hardware not found, passing devices to unprivileged domains is insecure.'.

All systems using an Intel processor and chipset that have support for Intel Virtualization Technology for Directed I/O (VT-d), but do not have support for interrupt remapping will see such an error. Interrupt remapping support is provided in newer processors and chipsets (both AMD and Intel).

To identify if your system has support for interrupt remapping:

<pre>
dmesg | grep 'remapping'
</pre>

If you see one of the following lines:

* <code>AMD-Vi: Interrupt remapping enabled</code>
* <code>DMAR-IR: Enabled IRQ remapping in x2apic mode</code> ('x2apic' can be different on old CPUs, but should still work)

then remapping is supported.

If your system doesn't support interrupt remapping, you can allow unsafe interrupts with:

<pre>
echo "options vfio_iommu_type1 allow_unsafe_interrupts=1" > /etc/modprobe.d/iommu_unsafe_interrupts.conf
</pre>

=== Verify IOMMU isolation ===

For working PCI passthrough, you need a dedicated IOMMU group for all PCI devices you want to assign to a VM.

When executing 

 # pvesh get /nodes/{nodename}/hardware/pci --pci-class-blacklist ""

replacing {nodename} with the name of your node.

You should get a list similar to:

<pre>
┌──────────┬────────┬──────────────┬────────────┬────────┬───────────────────────────────────────────────────────────────────┬...
│ class    │ device │ id           │ iommugroup │ vendor │ device_name                                                       │
╞══════════╪════════╪══════════════╪════════════╪════════╪═══════════════════════════════════════════════════════════════════╪
│ 0x010601 │ 0xa282 │ 0000:00:17.0 │          5 │ 0x8086 │ 200 Series PCH SATA controller [AHCI mode]                        │
├──────────┼────────┼──────────────┼────────────┼────────┼───────────────────────────────────────────────────────────────────┼
│ 0x010802 │ 0xa808 │ 0000:02:00.0 │         12 │ 0x144d │ NVMe SSD Controller SM981/PM981/PM983                             │
├──────────┼────────┼──────────────┼────────────┼────────┼───────────────────────────────────────────────────────────────────┼
│ 0x020000 │ 0x15b8 │ 0000:00:1f.6 │         11 │ 0x8086 │ Ethernet Connection (2) I219-V                                    │
├──────────┼────────┼──────────────┼────────────┼────────┼───────────────────────────────────────────────────────────────────┼
│ 0x030000 │ 0x5912 │ 0000:00:02.0 │          2 │ 0x8086 │ HD Graphics 630                                                   │
├──────────┼────────┼──────────────┼────────────┼────────┼───────────────────────────────────────────────────────────────────┼
│ 0x030000 │ 0x1d01 │ 0000:01:00.0 │          1 │ 0x10de │ GP108 [GeForce GT 1030]                                           │
├──────────┼────────┼──────────────┼────────────┼────────┼───────────────────────────────────────────────────────────────────┼
.
.
.
</pre>

To have separate IOMMU groups, your processor needs to have support for a feature called ACS (Access Control Services). Make sure you enable the corresponding setting in your BIOS for this.

If you don't have dedicated IOMMU groups, you can try moving the card to another PCI slot.

Should that not work, you can try using [https://lkml.org/lkml/2013/5/30/513 Alex Williamson's ACS override patch]. However, this should be seen as a last option
and is [http://vfio.blogspot.be/2014/08/iommu-groups-inside-and-out.html not without risks].

As of writing, the ACS patch is part of the Proxmox VE kernel and can be invoked via [https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysboot_edit_kernel_cmdline Editing the kernel command line]. Add 
 pcie_acs_override=downstream
to the kernel boot command line (grub or systemd-boot) options.

More information can be found at [http://vfio.blogspot.com/ Alex Williamson's blog].

== GPU passthrough ==

{{Note|See http://blog.quindorian.org/2018/03/building-a-2u-amd-ryzen-server-proxmox-gpu-passthrough.html/ if you like an article with a How-To approach. (NOTE: you usually do not need the ROM-file dumping mentioned at the end!)}}

* AMD RADEON 5xxx, 6xxx, 7xxx, NVIDIA GeForce 7, 8, GTX 4xx, 5xx, 6xx, 7xx, 9xx, 10xx, 15xx, 16xx, and RTX 20xx have been reported working. Anything newer should work as well.
* AMD Navi (5xxx(XT)/6xxx(XT)) suffer from the reset bug (see https://github.com/gnif/vendor-reset), and while dedicated users have managed to get them to run, they require a lot more effort and will probably not work entirely stable (see the [[PCI_Passthrough#AMD_specific_issues|AMD specific issues]] for workarounds).
* You might need to load some specific options in grub.cfg or other tuning values to get your configuration specifically working/stable
* Here's a good forum thread of Arch Linux: https://bbs.archlinux.org/viewtopic.php?id=162768

For starters, it's often helpful if the host doesn't try to use the GPU, which avoids issues with the host driver unbinding and re-binding to the device. Sometimes making sure the host BIOS POST messages are displayed on a different GPU is helpful too. This can sometimes be acomplished via BIOS settings, moving the card to a different slot or enabling/disabling legacy boot support.

=== Blacklisting drivers ===

The following is a list of common drivers and how to blacklist them:

* AMD GPUs
<pre>
echo "blacklist amdgpu" >> /etc/modprobe.d/blacklist.conf
echo "blacklist radeon" >> /etc/modprobe.d/blacklist.conf
</pre>
* NVIDIA GPUs
<pre>
echo "blacklist nouveau" >> /etc/modprobe.d/blacklist.conf 
echo "blacklist nvidia*" >> /etc/modprobe.d/blacklist.conf 
</pre>
* Intel GPUs
<pre>
echo "blacklist i915" >> /etc/modprobe.d/blacklist.conf
</pre>
{{Note | If you are using an Intel iGPU and an Intel discrete GPU, blacklisting the Intel 'i915' drivers that the discrete GPU uses means the iGPU won't be able to use those drivers either.}}

After blacklisting, you will need to reboot.

=== How to know if a graphics card is UEFI (OVMF) compatible ===
Have a look at [[PCI passthrough#Requirements|the requirements section]]. Chances are you are using the BIOS listed for your device on the Techpowerup GPU ROM list, which will say if it is UEFI compatible or not.

Alternatively, you can dump your ROM and use Alex Williams rom-parser tool:

{{ Note | You will want to run the following commands logged in as root user (by running <code>su -</code>) or by wrapping them with <code>sudo sh -c "<code-snippet>"</code>, otherwise the bash-redirects in the code-snippets below won't work}}

Get and compile the software "rom-parser":
 git clone https://github.com/awilliam/rom-parser
 cd rom-parser
 make

Then dump the rom of you vga card:
 cd /sys/bus/pci/devices/0000:01:00.0/
 echo 1 > rom
 cat rom > /tmp/image.rom
 echo 0 > rom

and test it with:
 ./rom-parser /tmp/image.rom

The output should look like this:

 Valid ROM signature found @0h, PCIR offset 190h
  PCIR: type 0, vendor: 10de, device: 1280, class: 030000
  PCIR: revision 0, vendor revision: 1
 Valid ROM signature found @f400h, PCIR offset 1ch
  PCIR: type 3, vendor: 10de, device: 1280, class: 030000
  PCIR: revision 3, vendor revision: 0
   EFI: Signature Valid
  Last image

To be UEFI compatible, you need a "type 3" in the result.

=== The 'romfile' option ===

Some motherboards can't pass through GPUs on the first PCI(e) slot by default, because its vBIOS is shadowed during boot up. You need to capture its vBIOS when it is working "normally" (i.e. installed in a different slot), then you can move the card to slot 1 and start the vm using the dumped vBIOS.

To dump the bios:
<pre>
cd /sys/bus/pci/devices/0000:01:00.0/
echo 1 > rom
cat rom > /usr/share/kvm/vbios.bin
echo 0 > rom
</pre>

Then you can pass the vbios file (must be located in /usr/share/kvm/) with:
<pre>
hostpci0: 01:00,x-vga=on,romfile=vbios.bin
</pre>

=== Tips ===

Some Windows applications like GeForce Experience, Passmark Performance Test and SiSoftware Sandra can crash the VM.
You need to add:
<pre>
echo "options kvm ignore_msrs=1" > /etc/modprobe.d/kvm.conf
</pre>

If you see a lot of warning messages in your 'dmesg' system log, add the following instead:
<pre>
echo "options kvm ignore_msrs=1 report_ignored_msrs=0" > /etc/modprobe.d/kvm.conf
</pre>

==== Nvidia Tips ====
User have reported that NVIDIA Kepler K80 GPUs need this in vmid.conf:
<pre>
args: -machine pc,max-ram-below-4g=1G
</pre>

==  Troubleshooting ==

=== "BAR 3: can't reserve [mem]" error ===

If you have this error when you try to use the card for a VM:
<pre>
vfio-pci 0000:04:00.0: BAR 3: can't reserve [mem 0xca000000-0xcbffffff 64bit]
</pre>

you can try to add the following kernel command line option:
<pre>
video=efifb:off
</pre>

Check out the documentation about [https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysboot_edit_kernel_cmdline editing the kernel command line].

=== WSLg (Windows Subsystem for Linux GUI)===
If GUI apps don't open in WSLg, see [https://pve.proxmox.com/wiki/Windows_2022_guest_best_practices#Installing_WSL.28g.29 Windows 2022 guest best practices].

=== Black display in NoVNC/Spice ===

If you are passing through a GPU and are getting a black screen, you might need to change your display settings in the Guest OS. On Windows, this can be done by pressing the "Super/Windows" and "P" key. Alternatively, if you are using the GPU for hardware accelerated computing and need no graphical output from it, you can deselect the "primary GPU" option and physically disconnect your GPU.

=== Spice ===

Spice may give trouble when passing through a GPU as it presents a "virtual" PCI graphic card to the guest and some drivers have problems with that, even when both cards show up.
It's always worth a try to disable SPICE and check again if something fails.

=== HDMI audio crackling/broken ===

Some digital audio devices (usually added via GPU functions) may require MSI (Message Signaled Interrupts) to be enabled to function correctly. If you experience any issues, try changing MSI settings in the guest and rebooting the guest.

Linux guests usually enable MSI by themselves. To force use of MSI for GPU audio devices, use the following command and reboot:

<pre>
echo "options snd-hda-intel enable_msi=1" >> /etc/modprobe.d/snd-hda-intel.conf
</pre>

Use 'lspci -vv' and check for the following line on your device to see if MSI is enabled:

<pre>
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
</pre>

If it says 'Enable+', MSI is working, 'Enable-' means it is supported but disabled, and if the line is missing, MSI is not supported by the PCIe hardware.

This can potentially also improve performance for other passthrough devices, including GPUs, but that depends on the hardware being used.

=== BIOS options ===

Make sure you are using the most recent BIOS version for you motherboard. Often IOMMU groupings or passthrough support in general is improved in later versions.

Some general BIOS options that might need changing to allow passthrough to work:

* IOMMU or VT-d: Set to 'Enabled' or equivalent, often 'Auto' is not the same
* 'Legacy boot' or CSM: For GPU passthrough it can help to disable this, but keep in mind that PVE has to be installed in UEFI mode, as it will not boot in BIOS mode without this enabled. The reason for disabling this is that it avoids legacy VGA initialization of installed GPUs, making them able to be re-initialized later, as required for passthrough. Most useful when trying to use passthrough in single GPU systems.
* 'Resizable BAR'/'Smart Access Memory': Some AMD GPUs (Vega and up) experience 'Code 43' in Windows guests if this is enabled on the host. It's not supported in VMs either way (yet), so the recommended setting is 'off'.

=== Error 43 ===
[https://support.microsoft.com/en-us/windows/fix-graphics-device-problems-with-error-code-43-6f6ae1ec-0bbe-a848-142e-0c6190502842 Error code 43] is a generic Windows driver error and can occur for a wide number of reasons. Things you can try troubleshooting include:

==== Finding out if the PCI device has a hardware fault ====
* Try passing the PCI device to a Linux VM
* Try plugging the PCI device into a different PCI slot or into a different machine

==== Finding software issues ====
* Check the security event logs of your Windows VM
* Check the dmesg logs of your host machine
* [[PCI Passthrough#How_to_know_if_a_Graphics_Card_is_UEFI_.28OVMF.29_compatible|Dump your vBIOS]] and check if it is working correctly.
* Try a different vbios (see [[PCI_passthrough#Requirements| the GPU requirements section]])
* If your GPU supports resizable BAR/SAM and you have this option set in your BIOS, you might need to deactivate it or manually tweak your BAR using an udev rule (see [https://wiki.archlinux.org/title/PCI_passthrough_via_OVMF#Code_43_while_Resizable_Bar_is_turned_on_in_the_bios Code 43 while Resizable Bar is turned on in the bios] in the Arch wiki)
* Sometimes the issue is very hardware-dependent. You might find someone else who found a solution who has the same hardware. Try searching the internet with keywords containing your hardware, together with keywords like "Proxmox", "KVM", or "Qemu".

==== Nvidia specific issues ====

When passing through mobile- or vGPUs, it might be necessary to spoof the Vendor ID and Hardware ID as if the passed-through GPU were the desktop variant. Changing the IDs might also be needed to remove manufacturer-specific vendor ID variants that are not recognized otherwise.

The Vendor and Device ID can be added in the web interface under "Hardware" -> "PCI Device (hostpciX)" and then clicking on the "Advanced" checkbox.

Some software will also refuse to run when it detects that it is running in a VM. This should no longer be an issue with Nvidia drivers 465 and newer.

To find the Vendor ID and Device ID of the card installed on your host, run:
 lspci -nn
which will give you something similar to
 01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GP108 [GeForce GT 1030] [10de:1d01] (rev a1)
Here, <code>0x10de</code> is the Vendor ID and <code>0x1d01</code> the Device ID.

==== AMD specific issues ====
Some AMD cards suffer from the "AMD reset bug" where the GPU does not correctly reset after power cycling. This can be remedied with the [https://github.com/gnif/vendor-reset/ vendor-reset patch]. See also [https://www.nicksherlock.com/2020/11/working-around-the-amd-gpu-reset-bug-on-proxmox/ Nick Sherlock's writeup] on the issue.

== USB passthrough ==
If you need to pass through USB devices (keyboard, mouse), please follow the [[USB Physical Port Mapping]] wiki article.

== vGPU ==
If you want to split up one GPU into multiple vGPUs, see:
* [https://pve.proxmox.com/wiki/MxGPU_with_AMD_S7150_under_Proxmox_VE_5.x MxGPU with AMD S7150]
* [https://pve.proxmox.com/wiki/NVIDIA_vGPU_on_Proxmox_VE_7.x NVIDIA vGPU]

[[Category:Staging]]
```
## vGPUs

```wiki
== Introduction ==

This is a Testing Report and How-To for using the MxGPU feature of an AMD S7150 Graphics card under PVE 5.x.
These cards can provide hardware-accelerated 3D graphics to multiple VMs with a single card instead of using one card per VM (normal PCI passthrough) or using a software 3D graphics card (QXL/Spice).

AMDs open source GIM driver<ref name="gim">GIM Open Source Driver. https://github.com/GPUOpen-LibrariesAndSDKs/MxGPU-Virtualization</ref> is needed on the host.

'''WARNING: Our tests showed that this may be unstable and experimental, please see the 'Notes' section below for more details.'''

== Hardware Notes ==

We tested the card in the following configurations:
{| class="wikitable"
|-
! Works !! Hardware Type !! Mainboard !! CPU !! Memory !! Errors !! Notes
|-
| No || Consumer || ASUS Z170-A || Intel 6700k || 32GB DDR4 Memory || Loading GIM failed with a PCI Bus Error that it did not have sufficient resources. || The firmware of the Mainboard is not suited for this use.
|-
| No || Low-end Server || Supermicro X10SDV-6C-TLN4F || Intel Xeon D-1528 || 32GB DDR4 Memory || PCI Bus Errors during use resulting in guest and host crashes. || The Platform is not suited for this use.
|-
| Yes || High-end Server || Supermicro H11SSL-i || AMD Epyc 7351P 16-Core Processor || 64 GB DDR4 Memory || Linux guest instability || OPROM for this card has to be set to Legacy.
|}

== Host Configuration ==

Make sure that the 'amdgpu' module is blacklisted before installing the card.
This can be done via a file in /etc/modprobe.d/. For example put

 blacklist amdgpu

into /etc/modprobe.d/blacklist-amdgpu.conf

Do not forget to update the initramfs<ref name="initramfs">https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_pci_passthrough_update_initramfs</ref> afterwards.

After that, you have to compile and install GIM<ref name="gim" />. For this, you need at least the packages 'git', 'pve-headers', 'gcc' and 'make'.

See their documentation about how you can compile and configure the module.

You can install the module via DKMS<ref>Debian DKMS documentation. https://wiki.debian.org/KernelDKMS</ref> (dynamic kernel module support),
then the module gets automatically recompiled on every kernel upgrade.

After installing the module, you can do

 modprobe gim

and now you should see the virtual functions via 'lspci'.
Example output:
  ...
  41:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] TongaXT GL [FirePro S7150]                                                                        
  41:02.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] TongaXTV GL [FirePro S7150V]
  41:02.1 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] TongaXTV GL [FirePro S7150V]
  ...

Those Devices (FirePro S7150V) can now be passed through via the standard PCI passthrough mechanism<ref name="passthrough">PCI Passthrough Documentation https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_pci_passthrough</ref>.

== Client Configuration ==

=== Windows 10 ===

Create a new VM, pass through a Virtual GPU, and install Windows 10.

After that, enable Remote Desktop and install the Radeon Pro Drivers<ref name="drivers">AMD Radeon Pro Drivers for S7150 https://www.amd.com/en/support/professional-graphics/firepro/firepro-s-series/firepro-s7150-active-cooling</ref>.

After a reboot of the VM, you can now connect via Remote Desktop to the VM and use the graphics card.

<gallery>
File:Windows 10 Blender.png|Rendering with OpenCL in Blender in Windows 10
File:Windows 10 Unigine Valley.png|Running Unigine Valley Benchmark in Windows 10
</gallery>

=== Ubuntu 18.04 ===

Create a new VM without passing through the Virtual GPU yet, and install Ubuntu 18.04.

After that, install the amdgpu-pro driver from AMDs homepage<ref name="drivers" />.

While testing, we found that the AMDGPU Pro driver Version 18.40<ref>AMDGPU Pro Driver 18.40. https://www.amd.com/en/support/kb/release-notes/rn-prorad-lin-18-40</ref> works most of the time. (18.30 did load but produced many guest kernel errors and prevented the use of it; 18.50 resulted in guest kernel oopses).

Install a desktop environment (for example XFCE with the meta-package xubuntu-desktop) and a display manager (for instance lightdm).

Install a VNC Server<ref>https://help.ubuntu.com/community/VNC/Servers
</ref> (or similar) to be able to access a local X server and configure it to start automatically.

Now power off the VM, add the virtual function and start the VM again.

Note: Depending on the exact guest kernel and driver version, there may be some kernel errors and warning even if it is working.

At this point, you should be able to connect via VNC (or another protocol) and use the virtual GPU.

<gallery>
File:Valley ubuntu 18.04.png|Unigine Valley on Ubuntu 18.04
File:Ubuntu supertuxkart.png||Super Tux Kart on Ubuntu 18.04
</gallery>

== Notes ==

=== Stability ===

In our tests the Linux guest drivers were very unstable. It worked with a single Ubuntu guest, but led to chrashes/hangs (of the guests and the host) after another guest was started, regardless of the client OS of the other guests.

The Windows guest drivers worked more stable, but there were occasional resets/crashes and sometimes blue screens in the guest after starting multiple Windows guests, this only occurred when at least one Linux guest was started since boot, so only starting and using Windows guests should work. (The relevant bug report is here: https://github.com/GPUOpen-LibrariesAndSDKs/MxGPU-Virtualization/issues/16)

=== Debugging ===

For debugging purposes, AMD includes the useful tool 'GRU' with the sources of GIM<ref name="gim" />. This is found in the 'utils/gru' folder and can simply be built with
'make'.

You can use this Tool to see which functions are in use and how much resources are used. Also, it provides a mechanism to reset the card and its functions.
Here is an example output:

 GRU
 Copyright (C) 2017~2018  Advanced Micro Devices, Inc.
 
 Type 'help' for help. Optional launch parameter is index of card to use.
 GRU> status
 
 +-----+--------------+----------+------------+-----------+--------------------+
 | GPU | Name         | Cur Volt | GFX EngClk | Mem Usage | Current DPM Level  |
 |     | BusId        | Temp     | Avail VF   | GFX Usage | Power Usage        |
 +=====+==============+==========+============+===========+====================+
 |   0 | S7150        | 0.5750 V | 313.10 MHz | 49.79 %   | 1                  |
 |     | 0000:41:00.0 | 57.00 C  | 2          | 45.17 %   | 33.37 W            |
 +-----+--------------+----------+------------+-----------+--------------------+
 GRU> list
 
 +-----+--------------+---------+------------+--------+------------+-----------+
 | GPU | Name         | DPM Cap | FB Size    | Max VF | GFX Engine | PL Speed  |
 |     | BusId        | PWR Cap | Encoder    | ECC    | MAX Clock  | PL Width  |
 +=====+==============+=========+============+========+============+===========+
 |   0 | S7150        | 8       | 8190 M     | 4      | GFX8       | 8 GT/s    |
 |     | 0000:41:00.0 | 109 W   | None       | No     | 1000 MHz   | x16       |
 +-----+--------------+---------+------------+--------+------------+-----------+
 GRU> open 0000:41:00.0
 GRU>GPU:41:00.0> list
 
 +----+--------+--------------+------------+-----------+---------+-------------+
 | VF | Type   | BusId        | Name       | VF State  | VF Size | GFX EngPart |
 +====+========+==============+============+===========+=========+=============+
 |  0 | S7150  | 0000:41:02.0 | MxGPU_V1_4 | Active    | 1968 M  | 25%         |
 +----+--------+--------------+------------+-----------+---------+-------------+
 |  1 | S7150  | 0000:41:02.1 | MxGPU_V1_4 | Active    | 1968 M  | 25%         |
 +----+--------+--------------+------------+-----------+---------+-------------+
 |  2 | S7150  | 0000:41:02.2 | MxGPU_V1_4 | Available | 1968 M  | 25%         |
 +----+--------+--------------+------------+-----------+---------+-------------+
 |  3 | S7150  | 0000:41:02.3 | MxGPU_V1_4 | Available | 1968 M  | 25%         |
 +----+--------+--------------+------------+-----------+---------+-------------+
 GRU>GPU:41:00.0> status 
 
 +----+-------------+--------------+--------------+--------------+-------------+
 | VF | Type        | BusId        | Active Time  | Running Time | Reset Times |
 +====+=============+==============+==============+==============+=============+
 |  0 | S7150       | 0000:41:02.0 | 0:41:48      | 0:59:29      | 0           |
 +----+-------------+--------------+--------------+--------------+-------------+
 |  1 | S7150       | 0000:41:02.1 | 0:14:13      | 0:31:50      | 0           |
 +----+-------------+--------------+--------------+--------------+-------------+
 |  2 | S7150       | 0000:41:02.2 | 0:0:0        | 0:0:0        | 0           |
 +----+-------------+--------------+--------------+--------------+-------------+
 |  3 | S7150       | 0000:41:02.3 | 0:0:0        | 0:0:0        | 0           |
 +----+-------------+--------------+--------------+--------------+-------------+
 GRU>GPU:41:00.0> 

==References==
<references />

[[Category: HOWTO]]
[[Category: Qemu/KVM]]
```

## NVIDIA vGPU on Proxmox VE

```wiki== Introduction ==

NVIDIA vGPU technology enables multiple virtual machines to use a single supported<ref name="supported-gpus">NVIDIA GPUs supported by vGPU https://docs.nvidia.com/grid/gpus-supported-by-vgpu.html</ref> physical GPU.

This article explains how to use NVIDIA vGPU on Proxmox VE. The instructions were tested using an RTX A5000.

== Disclaimer ==

At the time of writing, Proxmox VE is not an officially supported platform for NVIDIA vGPU. This means that even with valid vGPU licenses, you may not be eligible for NVIDIA enterprise support for this use-case.
However, Proxmox VE's kernel is derived from the Ubuntu kernel, which is a supported platform for NVIDIA vGPU as of 2024.

Note that although we are using some consumer hardware in this article, for optimal performance in production workloads, we recommend using appropriate enterprise-grade hardware.
Please refer to NVIDIA's support page to verify hardware compatibility
<ref>NVIDIA vGPU Certified Servers https://www.nvidia.com/en-us/data-center/resources/vgpu-certified-servers/</ref>
<ref name="supported-gpus">NVIDIA GPUs supported by vGPU https://docs.nvidia.com/grid/gpus-supported-by-vgpu.html</ref>.

== Hardware Setup ==

We're using the following hardware configuration for our test:

{| class="wikitable"
|+ Test System
|-
| CPU || Intel Core i7-12700K
|-
| Motherboard || ASUS PRIME Z690-A
|-
| Memory || 128 GB DDR5 Memory: 4x Crucial CT32G48C40U5
|-
| GPU || PNY NVIDIA RTX A5000
|}

Some NVIDIA GPUs do not have vGPU enabled by default, even though they support vGPU, like the RTX A5000 we tested. To enable vGPU there, switch the display using the NVIDIA Display Mode Selector Tool<ref>NVIDIA Display Mode Selector Tool https://developer.nvidia.com/displaymodeselector</ref>.
This will disable the display ports.

For a list of GPUs where this is necessary check their documentation<ref>Latest NVIDIA vGPU user guide: Switching the Mode of a GPU that Supports Multiple Display Modes https://docs.nvidia.com/grid/latest/grid-vgpu-user-guide/index.html#displaymodeselector</ref>.

The installation was tested on the following versions of Proxmox VE, Linux kernel, and NVIDIA drivers:

{| class="wikitable"
|-
! pve-manager !! kernel !! vGPU Software Branch !! NVIDIA Host drivers
|-
| 7.2-7 || 5.15.39-2-pve || 14.1 || 510.73.06
|-
| 7.2-7 || 5.15.39-2-pve || 14.2 || 510.85.03
|-
| 7.4-3 || 5.15.107-2-pve || 15.2 || 525.105.14
|-
| 7.4-17 || 6.2.16-20-bpo11-pve || 16.0 || 535.54.06
|-
| 8.1.4 || 6.5.11-8-pve || 16.3 || 535.154.02
|-
| 8.1.4 || 6.5.13-1-pve || 16.3 || 535.154.02
|}

It is recommended to use the latest stable and supported version of Proxmox VE and NVIDIA drivers.
However, newer versions in one vGPU Software Branch should also work for the same or older kernel version.

Since version 16.0, certain cards are no longer supported by the NVIDIA vGPU driver, but are supported by the Enterprise AI driver
<ref name="supported-gpus">NVIDIA GPUs supported by vGPU https://docs.nvidia.com/grid/gpus-supported-by-vgpu.html</ref>
<ref name="supported-gpus-ai">NVIDIA GPUs supported by AI Enterprise https://docs.nvidia.com/ai-enterprise/latest/product-support-matrix/index.html</ref>.
We have tested the Enterprise AI driver with an A16 and vGPU technology and found that it behaves similarly to the old vGPU driver. Therefore, the following steps also apply.

== Preparation ==

Before actually installing the host drivers, there are a few steps to be done on the Proxmox VE host.

'''Tip''': If you need to use a root shell, you can, for example, open one by connecting via SSH or using the node shell on the Proxmox VE web interface.

=== Enable PCIe Passthrough ===

Make sure that your system is compatible with PCIe passthrough. See the [https://pve.proxmox.com/wiki/PCI(e)_Passthrough PCI(e) Passthrough] documentation.

Additionally, confirm that the following features are enabled in your firmware settings (BIOS/UEFI):

* VT-d for Intel, or AMD-v for AMD (sometimes named IOMMU)
* SR-IOV (this may not be necessary for older pre-Ampere GPU generations)
* Above 4G decoding
* PCI AER (Advanced Error Reporting)
* PCI ASPM (Active State Power Management)

The firmware of your host might use different naming. If you are unable to locate some of these options, refer to the documentation provided by your firmware or motherboard manufacturer.

'''Note''': It is crucial to ensure that both the IOMMU options are enabled in your firmware and the kernel.

=== Setup Proxmox VE Repositories ===

Proxmox VE's comes with the enterprise repository set up by default as this repository provides better tested software and is recommended for production use.
The enterprise repository needs a valid subscription per node. For evaluation or non-production use cases you can simply switch to the public <code>no-subscription</code> repository. This provides the same feature-set but with a higher frequency of updates.

You can use the <code>Repositories</code> management panel in the Proxmox VE web UI for managing package repositories, see the [https://pve.proxmox.com/wiki/Package_Repositories documentation] for details.

=== Update to Latest Package Versions ===

Proxmox VE uses a rolling release model and should be updated frequently to ensure that your Proxmox VE installation has the latest bug and security fixes, and features available.

You can update your Proxmox VE node using the <code>update</code> panel on the web UI.

=== Blacklist the Nouveau Driver  ===

Next, you want to blacklist the open source <code>nouveau</code> kernel module to avoid it from interfering with the one from NVIDIA.

To do that, add a line with <code>blacklist nouveau</code> to a file in the <code>/etc/modprobe.d/</code> directory.
For example, open a root shell and execute:
 echo "blacklist nouveau" >> /etc/modprobe.d/blacklist.conf

Then, [https://pve.proxmox.com/wiki/PCI(e)_Passthrough#qm_pci_passthrough_update_initramfs update your initramfs], to ensure that the module is blocked from loading at early boot, and then reboot your host.

=== Setup DKMS ===

Because the NVIDIA module is separate from the kernel, it must be rebuilt with Dynamic Kernel Module Support (DKMS) for each new kernel update.

To set up DKMS, you must install the headers package for the kernel and the DKMS helper package. In a root shell, run

 apt update
 apt install dkms libc6-dev proxmox-default-headers --no-install-recommends

'''Note''': If you do not have the default kernel version installed, but for example an opt-in kernel, you must install the appropriate <code>proxmox-headers-X.Y</code> package instead of <code>proxmox-default-headers</code>.

== Host Driver Installation ==

'''Note''': The driver/file versions shown in this section are examples only; use the correct file names for the selected driver you're installing.

To get started, you will need the appropriate host and guest drivers; see the NVIDIA Virtual GPU Software Quick Start Guide<ref>Getting your NVIDIA GRID Software: https://docs.nvidia.com/grid/latest/grid-software-quick-start-guide/index.html#getting-your-nvidia-grid-software</ref> for instructions on how to obtain them.
Choose <code>Linux KVM</code> as target hypervisor when downloading.

In our case we got the following host driver file:
 NVIDIA-Linux-x86_64-525.105.14-vgpu-kvm.run
Copy this file over to your Proxmox VE node.

To start the installation, you need to make the installer executable first, and then pass the <code>--dkms</code> option when running it, to ensure that the module is rebuilt after a kernel upgrade:
 chmod +x NVIDIA-Linux-x86_64-525.105.14-vgpu-kvm.run
 ./NVIDIA-Linux-x86_64-525.105.14-vgpu-kvm.run --dkms
Follow the steps of the installer.

After the installer has finished successfully, you will need to reboot your system, either using the web interface or by executing <code>reboot</code>.

=== Enabling SR-IOV ===

On some NVIDIA GPUs (for example, those based on the Ampere architecture), you must first enable SR-IOV before being able to use vGPUs.
You can do that with the <code>sriov-manage</code> script from NVIDIA.

 /usr/lib/nvidia/sriov-manage -e <pciid|ALL>
<!-- TODO: describe what <pci-id|ALL> is and why not always all, ...  -->

Since that setting gets lost on reboot, it might be a good idea to write a cronjob or systemd service to enable it on reboot.

Here is an example systemd service for enabling SR-IOV on all found NVIDIA GPUs:

<pre>
[Unit]
Description=Enable NVIDIA SR-IOV
After=network.target nvidia-vgpud.service nvidia-vgpu-mgr.service
Before=pve-guests.service

[Service]
Type=oneshot
ExecStart=/usr/lib/nvidia/sriov-manage -e ALL

[Install]
WantedBy=multi-user.target
</pre>

Depending on the actual hardware, it might be necessary to give the <code>nvidia-vgpud.service</code> a bit more time to start, you can do that by adding
 ExecStartPre=/bin/sleep 5
just before the <code>ExecStart</code> line in the service file (replace '5' by an appropriate amount of seconds).

You can save this in <code>/usr/local/lib/systemd/system/nvidia-sriov.service</code>. Then enable and start it with:

 systemctl daemon-reload
 systemctl enable --now nvidia-sriov.service

This will then run after the <code>nvidia-daemons</code> got started, but before the Proxmox VE virtual guest auto start-up.

Verify that there are multiple virtual functions for your device with:

 # lspci -d 10de:

In our case there are now 24 virtual functions in addition to the physical card (01:00.0):

 01:00.0 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:00.4 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:00.5 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:00.6 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:00.7 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.0 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.1 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.2 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.3 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.4 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.5 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.6 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:01.7 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.0 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.1 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.2 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.3 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.4 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.5 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.6 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:02.7 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:03.0 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:03.1 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:03.2 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)
 01:03.3 3D controller: NVIDIA Corporation GA102GL [RTX A5000] (rev a1)

== Guest Configuration ==

=== General Setup ===

First, set up a VM as you normally would, without adding a vGPU.

After configuring the VM to your liking, shut down the VM and add a vGPU by selecting one of the virtual functions and selecting the appropriate mediated device type.

For example:

Via the CLI:

 qm set VMID -hostpci0 01:00.4,mdev=nvidia-660

Via the web interface:

[[File:Pve select vgpu.png|500px|none|Selecting a vGPU model]]

To find the correct mediated device type, you can use <code>sysfs</code>.
Here is a sample shell script that prints the type, then the name (which corresponds to the NVIDIA documentation) and the description, which contains helpful information (such as the maximum number of instances available).
Adjust the PCI path to your needs:

<pre>
#!/bin/sh
set -e

for i in /sys/bus/pci/devices/0000:01:00.4/mdev_supported_types/*; do
    basename "$i"
    cat "$i/name"
    cat "$i/description"
    echo
done
</pre>

Since pve-manager version 7.2-8 and libpve-common-perl version 7.2-3, the GUI shows the correct name for the type.

If your qemu-server version is below 7.2-4, you must add an additional parameter
to the vm:

 # qm set VMID -args '-uuid <UUID-OF-THE-MDEV>'

The UUID of the mediated device is automatically generated from the VMID and the <code>hostpciX</code> index of the config, where the host PCI index is used as the first part and the VMID as the last part.
For example, if you configure <code>hostpci2</code> for VM with VMID <code>12345</code>, the generated UUID will be

 00000002-0000-0000-0000-000000012345

You can now start the VM and continue configuring the guest from within.

We tested a Windows 10 and Ubuntu 22.04 installation, but the setup will be similar for other supported operating systems.

=== Windows 10 ===

First install and configure a desktop sharing software that matches your requirements. Some
examples of such software include:

* '''VNC'''<br />many different options, some free, some commercial
* '''Remote Desktop'''<br />built into Windows itself
* '''Parsec'''<br />Costs money for commercial use, allows using hardware accelerated encoding
* '''RustDesk'''<br />free and open source, but relatively new as of 2022

We used simple Windows built-in remote desktop for testing.

[[File:Windows rdp.png|thumb|Enabling Remote Desktop in Windows 10]]

Then you can install the Windows guest driver that is published by NVIDIA.
Refer to their documentation<ref name="gpu-mapping">NVIDIA Virtual GPU (vGPU) Software Documentation https://docs.nvidia.com/grid/</ref>to find a compatible guest driver to host driver mapping.
In our case this was the file

 528.89_grid_win10_win11_server2019_server2022_dch_64bit_international.exe

Start the installer and follow the instructions, then, after it finished restart the guest as prompted.

<gallery>
Windows nv install01.png|Starting NVIDIA driver installation
Windows nv install02.png|Accepting the license agreement
Windows nv install03.png|Finishing the installation
</gallery>

From this point on, the integrated noVNC console of PVE will not be usable anymore, so use
your desktop sharing software to connect to the guest. Now you can use the vGPU for starting
3D applications such as Blender, 3D games, etc.

<gallery>
Windows valley.png|Unigine Valley
Windows supertuxkart.png|SuperTuxKart
Windows blender.png|Blender
</gallery>

=== Ubuntu 22.04 Desktop ===

Before installing the guest driver, install and configure a desktop sharing software, for example:

* '''VNC'''<br />many options. We use x11vnc here, which is free and open source, but does not currently provide hardware accelerated encoding
* '''NoMachine'''</br>provides hardware accelerated encoding, but is not open source and costs money for business use
* '''RustDesk'''<br />free and open source, but relatively new as of 2022

We installed x11vnc in this example. While we're showing how to install and configure it, this is not the only way to achieve the goal of having properly configured desktop sharing.

Since Ubuntu 22.04 ships GDM3 + Gnome + Wayland per default, you first need to switch the login manager to one that uses X.org.
We successfully tested LightDM here, but others may work as well.

 # apt install lightdm

Select 'LightDM' as default login manager when prompted. After that install <code>x11vnc</code> with

 # apt install x11vnc

We then added a systemd service that starts the VNC server on the x.org server provided by LightDM in <code>/etc/systemd/system/x11vnc.service</code>

<pre>
[Unit]
Description=Start x11vnc
After=multi-user.target

[Service]
Type=simple
ExecStart=/usr/bin/x11vnc -display :0 -auth /var/run/lightdm/root/:0 -forever -loop -repeat -rfbauth /etc/x11vnc.passwd -rfbport 5900 -shared -noxdamage

[Install]
WantedBy=multi-user.target
</pre>

You can set the password by executing:

 # x11vnc -storepasswd /etc/x11vnc.passwd
 # chmod 0400 /etc/x11vnc.passwd

After setting up LightDM and x11vnc and restarting the VM, you can connect via VNC.

Now, install the .deb package that NVIDIA provides for Ubuntu.
Check the NVIDIA documentation<ref name="gpu-mapping" /> for a compatible guest driver to host driver mapping.

In our case this was <code>nvidia-linux-grid-525_525.105.17_amd64.deb</code>, and we directly installed from the local file using apt.
For that to work you must prefix the relative path, for example <code>./</code> if the <code>.deb</code> file is located in the current directory.

 # apt install ./nvidia-linux-grid-525_525.105.17_amd64.deb

Then you must use NVIDIA's tools to configure the x.org configuration with:

 # nvidia-xconfig

Now you can reboot and use a VNC client to connect and use the vGPU for 3D applications.

<gallery>
Ubuntu valley.png|Unigine Valley
Nv Ubuntu supertuxkart.png|SuperTuxKart
Ubuntu blender.png|Blender
</gallery>

{{Note| If you want to use CUDA on a Linux Guest, you must install the CUDA Toolkit manually<ref>NVIDIA CUDA Toolkit Download https://developer.nvidia.com/cuda-downloads</ref>.
Check the NVIDIA documentation which version of CUDA is supported for your vGPU drivers.

In our case we needed to install CUDA 11.6 (only the toolkit, not the driver) with the file:

 cuda_11.6.2_510.47.03_linux.run 
|warn}}

=== Guest vGPU Licensing ===

To use the vGPU without restriction, you must adhere to NVIDIA's licensing.
Check the NVIDIA vGPU documentation<ref>NVIDIA GRID Licensing User Guide: https://docs.nvidia.com/grid/latest/grid-licensing-user-guide/index.html</ref> for instructions on how to do so.

'''Tip''': Ensure that the guest system time is properly synchronized using NTP, otherwise the guest will be unable to request a license for the vGPU.

== Notes ==
<references />

[[Category: HOWTO]]
[[Category: Qemu/KVM]]
```