[PATCH pve-docs v2 2/8] qm: add reboot behavior information

[Jakob Klocker <j.klocker@proxmox.com>]

Add information about the newly created `Reboot behavior` option in PVE.

Signed-off-by: Jakob Klocker <j.klocker@proxmox.com>
---
 qm.adoc | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/qm.adoc b/qm.adoc
index 18a4fbe..04193e8 100644
--- a/qm.adoc
+++ b/qm.adoc
@@ -1558,6 +1558,46 @@ cluster-wide.
 If you require a delay between the host boot and the booting of the first VM,
 see the section on xref:first_guest_boot_delay[Proxmox VE Node Management].
 
+[[qm_reboot_behavior]]
+Reboot Behavior
+~~~~~~~~~~~~~~~
+
+When a guest reboots itself from inside the operating system, {pve} does not
+need to restart the virtual machine to service the request. By default the
+machine is reset in place: the QEMU process keeps running and only the guest
+operating system boots again.
+
+This is fast and transparent to the guest, but it means the VM keeps running
+with everything it was started with - its configuration, its machine version
+and the host resources assigned to it. Configuration changes that are marked as
+*pending* in the *Options* and hardware panels therefore stay pending, and a
+newer `pve-qemu-kvm` package installed in the meantime is not picked up. A
+reboot triggered through the web interface, `qm` or the API is not affected by
+this, as it always stops and starts the virtual machine, unless rebooting is
+disabled entirely.
+
+The `reboot` option has two properties:
+
+`enabled` (default: `1`)::
+Whether the virtual machine may reboot at all. If disabled, a reboot requested
+from inside the guest or through `qm reboot` or the API shuts the VM down
+instead, and it stays off. The exception is an explicit reset (`qm reset`, the
+API or the web interface), which still restarts the VM. Note that guests managed
+by the xref:chapter_ha_manager[HA stack] with the requested state `started` are
+started again by the HA manager.
+
+`powercycle` (default: `0`)::
+Stop and start the virtual machine on a reset instead of resetting it in place.
+A reset is what a reboot from inside the guest looks like to QEMU, and it is
+also what `qm reset` and the corresponding API call and web interface action
+trigger. Because this is a full start, pending configuration changes take
+effect and the VM is launched with the currently installed QEMU version, and
+the `post-stop` and `pre-start` hookscript phases run again. This property is
+ignored when `enabled` is `0`.
+
+----
+# qm set <vmid> --reboot 1,powercycle=1
+----
 
 [[qm_qemu_agent]]
 QEMU Guest Agent
-- 
2.47.3