add ivshmem documentation

[pve-docs.git] / qm.adoc

diff --git a/qm.adoc b/qm.adoc
index 4fc83718bdaa47504acde1e234e12802851f2b05..77fec9871b5927444f439f035ed4065e1bcc24e0 100644 (file)
--- a/qm.adoc
+++ b/qm.adoc
@@ -193,11 +193,21 @@ As of {pve} 5.0, replication requires the disk images to be on a storage of type
 configured requires to skip replication for this disk image.
 
 If your storage supports _thin provisioning_ (see the storage chapter in the
 configured requires to skip replication for this disk image.
 
 If your storage supports _thin provisioning_ (see the storage chapter in the

-{pve} guide), and your VM has a *SCSI* controller you can activate the *Discard*
-option on the hard disks connected to that controller. With *Discard* enabled,
-when the filesystem of a VM marks blocks as unused after removing files, the
-emulated SCSI controller will relay this information to the storage, which will
-then shrink the disk image accordingly.
+{pve} guide), you can activate the *Discard* option on a drive. With *Discard*
+set and a _TRIM_-enabled guest OS footnote:[TRIM, UNMAP, and discard
+https://en.wikipedia.org/wiki/Trim_%28computing%29], when the VM'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 either use a
+*VirtIO SCSI* (or *VirtIO SCSI Single*) controller or set the *SSD emulation*
+option on the drive. Note that *Discard* is not supported on *VirtIO Block*
+drives.
+
+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
 
 .IO Thread
 The option *IO Thread* can only be used when using a disk with the


@@ -427,7 +437,7 @@ 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
 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 sockets of the host system.
+the number of nodes of the host system.

 
 vCPU hot-plug
 ^^^^^^^^^^^^^
 
 vCPU hot-plug
 ^^^^^^^^^^^^^


@@ -590,6 +600,39 @@ 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.
 
 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.
 

+[[qm_display]]
+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 footnote:[https://www.kraxel.org/blog/2014/10/qemu-using-cirrus-considered-harmful/
+qemu: using cirrus considered harmful], e.g., 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 for the VM.
+
+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 (e.g., `qxl2` for dual monitors) has some implications:
+
+* Windows needs a device for each monitor, so if your 'ostype' is some
+version of Windows, {pve} 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.

 
 [[qm_usb_passthrough]]
 USB Passthrough
 
 [[qm_usb_passthrough]]
 USB Passthrough


@@ -660,6 +703,25 @@ 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.
 
 with a press of the ESC button during boot), or you have to choose
 SPICE as the display type.
 

+[[qm_ivshmem]]
+Inter-VM shared memory
+~~~~~~~~~~~~~~~~~~~~~~
+
+You can add a Inter-VM shared memory device (`ivshmem`) to be able to
+share memory between the host and a guest, or between multiple guests.
+
+To add such a device, you can use `qm`:
+
+  qm set <vmid> -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).
+
+A usecase for such a device is Looking Glass
+footnote:[Looking Glass: https://looking-glass.hostfission.com/]
+which enables high performance, low-latency display mirroring between
+host and guest.
+

 [[qm_startup_and_shutdown]]
 Automatic Start and Shutdown of Virtual Machines
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 [[qm_startup_and_shutdown]]
 Automatic Start and Shutdown of Virtual Machines
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


@@ -786,7 +848,7 @@ migrate a VM to a totally different storage. You can also change the
 disk image *Format* if the storage driver supports several formats.
 +
 
 disk image *Format* if the storage driver supports several formats.
 +
 

-NOTE: A full clone need to read and copy all VM image data. This is
+NOTE: A full clone needs to read and copy all VM image data. This is

 usually much slower than creating a linked clone.
 +
 
 usually much slower than creating a linked clone.
 +
 


@@ -797,7 +859,7 @@ never includes any additional snapshots from the original VM.
 
 Linked Clone::
 
 
 Linked Clone::
 

-Modern storage drivers supports a way to generate fast linked
+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.
 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.


@@ -814,8 +876,8 @@ can convert any VM into a read-only <<qm_templates, Template>>). Such
 templates can later be used to create linked clones efficiently.
 +
 
 templates can later be used to create linked clones efficiently.
 +
 

-NOTE: You cannot delete the original template while linked clones
-exists.
+NOTE: You cannot delete an original template while linked clones
+exist.

 +
 
 It is not possible to change the *Target storage* for linked clones,
 +
 
 It is not possible to change the *Target storage* for linked clones,


@@ -826,7 +888,7 @@ 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.
 
 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 gets
+To avoid resource conflicts, all network interface MAC addresses get

 randomized, and we generate a new 'UUID' for the VM BIOS (smbios1)
 setting.
 
 randomized, and we generate a new 'UUID' for the VM BIOS (smbios1)
 setting.
 


@@ -845,7 +907,7 @@ clone and modify that.
 VM Generation ID
 ----------------
 
 VM Generation ID
 ----------------
 

-{pve} supports Virtual Machine Generation ID ('vmgedid') footnote:[Official
+{pve} supports Virtual Machine Generation ID ('vmgenid') footnote:[Official

 'vmgenid' Specification
 https://docs.microsoft.com/en-us/windows/desktop/hyperv_v2/virtual-machine-generation-identifier]
 for virtual machines.
 'vmgenid' Specification
 https://docs.microsoft.com/en-us/windows/desktop/hyperv_v2/virtual-machine-generation-identifier]
 for virtual machines.


@@ -983,7 +1045,20 @@ ifndef::wiki[]
 include::qm-cloud-init.adoc[]
 endif::wiki[]
 
 include::qm-cloud-init.adoc[]
 endif::wiki[]
 

+ifndef::wiki[]
+include::qm-pci-passthrough.adoc[]
+endif::wiki[]
+
+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`.

 
 Managing Virtual Machines with `qm`
 ------------------------------------
 
 Managing Virtual Machines with `qm`
 ------------------------------------