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Save and restore (also known as suspend and resume) permits a snapshot to be taken of a guest's state that can later be resumed. In the current implementation, bhyve(8) creates a UNIX domain socket that is used by bhyvectl(8) to send a request to save a snapshot (and optionally exit after the snapshot has been taken). A snapshot currently consists of two files: the first holds a copy of guest RAM, and the second file holds other guest state such as vCPU register values and device model state. To resume a guest, bhyve(8) must be started with a matching pair of command line arguments to instantiate the same set of device models as well as a pointer to the saved snapshot. While the current implementation is useful for several uses cases, it has a few limitations. The file format for saving the guest state is tied to the ABI of internal bhyve structures and is not self-describing (in that it does not communicate the set of device models present in the system). In addition, the state saved for some device models closely matches the internal data structures which might prove a challenge for compatibility of snapshot files across a range of bhyve versions. The file format also does not currently support versioning of individual chunks of state. As a result, the current file format is not a fixed binary format and future revisions to save and restore will break binary compatiblity of snapshot files. The goal is to move to a more flexible format that adds versioning, etc. and at that point to commit to providing a reasonable level of compatibility. As a result, the current implementation is not enabled by default. It can be enabled via the WITH_BHYVE_SNAPSHOT=yes option for userland builds, and the kernel option BHYVE_SHAPSHOT. Submitted by: Mihai Tiganus, Flavius Anton, Darius Mihai Submitted by: Elena Mihailescu, Mihai Carabas, Sergiu Weisz Relnotes: yes Sponsored by: University Politehnica of Bucharest Sponsored by: Matthew Grooms (student scholarships) Sponsored by: iXsystems Differential Revision: https://reviews.freebsd.org/D19495
115 lines
3.4 KiB
Groff
115 lines
3.4 KiB
Groff
.\" Copyright (c) 2015 Christian Brueffer
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd May 04, 2020
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.Dt BHYVECTL 8
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.Os
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.Sh NAME
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.Nm bhyvectl
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.Nd "control utility for bhyve instances"
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.Sh SYNOPSIS
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.Nm
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.Fl -vm= Ns Ar <vmname>
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.Op Fl -create
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.Op Fl -destroy
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.Op Fl -get-stats
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.Op Fl -inject-nmi
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.Op Fl -force-reset
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.Op Fl -force-poweroff
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.Op Fl -checkpoint= Ns Ar <filename>
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.Op Fl -suspend= Ns Ar <filename>
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.Sh DESCRIPTION
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The
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.Nm
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command is a control utility for active
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.Xr bhyve 8
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virtual machine instances.
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.Pp
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.Em Note :
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Most
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.Nm
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flags are intended for querying and setting the state of an active instance.
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These commands are intended for development purposes, and are not documented here.
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A complete list can be obtained by executing
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.Nm
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without any arguments.
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.Pp
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The user-facing options are as follows:
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.Bl -tag -width ".Fl d Ar argument"
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.It Fl -vm= Ns Ar <vmname>
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Operate on the virtual machine
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.Ar <vmname> .
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.It Fl -create
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Create the specified VM.
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.It Fl -destroy
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Destroy the specified VM.
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.It Fl -get-stats
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Retrieve statistics for the specified VM.
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.It Fl -inject-nmi
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Inject a non-maskable interrupt (NMI) into the VM.
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.It Fl -force-reset
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Force the VM to reset.
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.It Fl -force-poweroff
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Force the VM to power off.
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.It Fl -checkpoint= Ns Ar <filename>
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Save a snapshot of a virtual machine.
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The guest memory contents are saved in the file given in
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.Ar <filename> .
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The guest device and vCPU state are saved in the file
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.Ar <filename>.kern .
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.It Fl -suspend= Ns Ar <filename>
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Save a snapshot of a virtual machine similar to
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.Fl -checkpoint .
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The virtual machine will terminate after the snapshot has been
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saved.
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.El
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.Sh EXIT STATUS
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.Ex -std
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.Sh EXAMPLES
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Destroy the VM called fbsd10:
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.Pp
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.Dl "bhyvectl --vm=fbsd10 --destroy"
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.Sh COMPATIBILITY
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The snapshot file format is not yet stable and is subject to future changes.
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Backwards compatibility support for the current snapshot file format is not
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guaranteed when future changes are made.
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.Sh SEE ALSO
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.Xr bhyve 8 ,
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.Xr bhyveload 8
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.Sh HISTORY
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The
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.Nm
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command first appeared in
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.Fx 10.1 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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utility was written by
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.An Peter Grehan
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and
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.An Neel Natu .
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