Scroll to navigation

guestfs-release-notes-1.38(1) Virtualization Support guestfs-release-notes-1.38(1)


guestfs-release-notes - libguestfs Release Notes


These release notes only cover the differences from the previous stable/dev branch split (1.36.0). For detailed changelogs, please see the git repository, or the ChangeLog file distributed in the tarball.

New features

New tools

Virt-builder-repository is a new tool allowing end users to create and update virt-builder repositories (Cédric Bosdonnat).

Virt-rescue (while not a new tool) has been substantially rewritten, implementing job control, -m and -i options, escape keys, etc.

New features in existing tools

Virt-builder planner has been improved so that faster and more efficient build plans are chosen for complex cases, especially when either the tmpdir or output is on networked storage.

New virt-builder Fedora templates (starting with Fedora 26) will have plain partition layout and use GPT for partitions.

Virt-customize "firstboot" scripts in guests using systemd are now installed under the "" instead of "" so they will only run when the system is booted normally.

Virt-customize now sets a random /etc/machine-id for Linux guests, if one is not already set.

Virt-df now works correctly on filesystems with block sizes smaller than 1K (Nikolay Ivanets).

Virt-dib has further compatibility enhancements with diskimage-builder (Pino Toscano).

Virt-sysprep removes "DHCP_HOSTNAME" from ifcfg-* files.

Virt-sysprep now works on Oracle Linux (Jamie Iles).

Virt-resize now correctly copies GPT partition attributes from the source to the destination (Cédric Bosdonnat).

Bash tab completion implemented or enhanced for: virt-win-reg, virt-v2v-copy-to-local.

virt-v2v and virt-p2v

Virt-v2v can now read VMware VMX files directly, either from local disk, NFS storage, or over SSH from an ESXi hypervisor.

Virt-v2v can now use VDDK as an input source.

Both virt-v2v and virt-p2v are now able to pass through the source CPU vendor, model and topology. However unfortunately not all source and target hypervisors are able to provide or consume this data at present (Tomáš Golembiovský).

Virt-v2v now supports encrypted guests (Pino Toscano).

Virt-v2v can now handle VMware snapshots. Note that the snapshots are collapsed — it does not convert the chain of snapshots into a chain of snapshots.

Virt-v2v now installs Windows 10 / Windows Server 2016 virtio block drivers correctly (Pavel Butsykin, Kun Wei).

Virt-v2v now installs virtio-rng, balloon and pvpanic drivers, and correctly sets this in the target hypervisor metadata for hypervisors which support that (Tomáš Golembiovský).

Virt-v2v now installs both legacy and modern virtio keys in the Windows registry (Ladi Prosek).

Virt-p2v can now preserve (in some cases) the offset of the Real Time Clock from UTC.

Virt-p2v now combines several scp commands to the conversion server into a single command, improving conversion times.

Virt-v2v now detects the special Linux Xen PV-only kernels correctly (Laszlo Ersek).

Virt-v2v -o glance now generates the right properties for UEFI guests (Pino Toscano).

Virt-v2v -o null now avoids spooling the guest to a temporary file, instead it writes to the qemu "null block device". This makes it faster and use almost no disk space.

Virt-v2v -o rhv now supports Windows 2016 Server guest type.

Virt-v2v -i libvirtxml can now open network disks over http or https.

Virt-v2v will now give a warning about host passthrough devices (Pino Toscano).

The virt-v2v --machine-readable output has been enhanced so it includes "vcenter-https", "xen-ssh" and "in-place" facts (Pino Toscano).

Language bindings

Fix multiple memory leaks and other data corruption problems in the Java bindings (Pino Toscano).

Perl %guestfs_introspection has been dropped.


Inspection support was rewritten in OCaml and included inside the daemon. This makes inspection considerably faster, more robust and more easily extensible in future.

Better icon support for ALT Linux guests (Pino Toscano).

Better support for NeoKylin (Qingzheng Zhang).

Can handle OSes like Void Linux which do not include "VERSION_ID" in /etc/os-release (Pino Toscano).

Add support for Microsoft MS-DOS (Daniel Berrangé).

Architectures and platforms

Multiple fixes for S/390 architecture. Libguestfs and all the tools should now compile and run on this architecture.


The libguestfs API is now thread-safe (although not parallel). You can call APIs on the same handle from multiple threads without needing to take a lock.


There were multiple vulnerabilities in the icoutils "wrestool" program which is run by libguestfs to create icons for Windows guests. Using the latest "wrestool" is recommended.


New APIs

This replaces the deprecated "hivex_value_utf8" API, but does the same thing.
Read and write GPT partition attribute flags (Cédric Bosdonnat).
Enlarge or shrink an existing partition (Nikos Skalkotos).
Support for the Yara malware scanning engine (Matteo Cafasso).

Other API changes

APIs implemented in the daemon can now be written in either C or OCaml. Several APIs were rewritten in OCaml, although we are not planning to rewrite all of them.

You will now get a clear error message if you try to add too many disks to the appliance, instead of getting a peculiar failure from qemu.

Certain APIs accidentally allowed you to use "/dev/urandom" as an input "device", eg. "g.copy_device_to_device("/dev/urandom", "/dev/sda")". The code has been modified to forbid this usage.

All APIs for inspecting installer CDs have been deprecated. Use libosinfo for this task.

Build changes

A working OCaml compiler ≥ 4.01 is now required for building libguestfs. The "./configure --disable-ocaml" option remains but is only used to disable the OCaml language bindings.

Add "RELEASES" file which lists release dates for each version of libguestfs. You must update this file when making a new release.

Documentation generated by "gtk-doc" has been removed. "./configure --enable-gtk-doc" now does nothing.

Libtirpc is now used for XDR functions and rpcgen. Note that glibc has deprecated and in most Linux distros dropped these, so for most people this will be an extra dependency (Martin Kletzander).

Libxcrypt is now used for crypt(3). This is required if using glibc ≥ 2.27.

"ocaml-hivex" is now required.

Libvirt ≥ 1.2.20 is now required.

There is now a "make check-root" target for tests which need to be run as root (analogous to "make check-slow").

"./configure"-time check for "__attribute__((cleanup))" now works in the cross-compilation case (Yann E. Morin).

The "AUTHORS" and "p2v/about-authors.c" files are now generated from a single place.

Either GnuPG v1 or v2 can be used.

"./configure --with-guestfs-path" may be used to set the default "LIBGUESTFS_PATH". In addition the way that the path is searched has changed slightly so that all types of appliances are searched in each path element separately (Pavel Butsykin).

"GUESTFSD_EXT_CMD" which was used to mark external commands in the daemon has been removed. It was originally used by SUSE builds, but they have not been using it for a while.

The output from "./configure" is now visually grouped under headings related to what it is doing, making it much easier to scan (Pino Toscano).

OCaml dependencies are now generated from a single script instead of multiple not-quite-the-same Makefile fragments.

"./configure --with-distro=ID" can be used to override automatic Linux distro detection at build time (Pino Toscano).

qemu ≥ 2.10 is supported (but not required). This adds mandatory locking to disks and libguestfs turns this off in certain circumstances when it is known to be safe (Lars Seipel, Peter Krempa, Daniel Berrangé, Pino Toscano, Fam Zheng, Yongkui Guo, Václav Kadlčík).


Most common code has been moved to the common/ subdirectory, with OCaml common code being in common/ml* directories (eg. common/visit and common/mlvisit contain the visitor library in C and OCaml respectively). The mllib directory has been deleted and replaced by common/mltools.

There is now a lightweight OCaml binding for PCRE, see common/mlpcre. Use of OCaml "Str" library has been mostly replaced with PCRE.

Add more calls to "udev_settle" to improve stability of partition code (Dawid Zamirski).

Run "udev_settle" with --exit-if-exists option, which improves the speed of this command (Pavel Butsykin).

Detect new locations of major(3), minor(3), makedev(3).

Actions can now be deprecated with no suggested replacement, for APIs such as "guestfs_wait_ready" that should simply be removed from client code.

Use gnulib "set_nonblocking_flag" wrapper instead of calling fcntl(2) with "O_NONBLOCK" (Eric Blake). Similarly "set_cloexec_flag".

Fix memory leak in XFS version of "guestfs_vfs_minimum_size" (Pino Toscano).

Valgrind checks now run on the virt-p2v binary.

Unicode single quotes ("‘’") and now used in place of '' or `' throughout the code and documentation. Similarly for "’s" instead of "'s".

The "is_zero" function has been reimplemented for greater speed (Eric Blake).

In the direct backend, virtio-blk support has been removed. Virtio-scsi is now the only supported way to add disks.

Generator string parameter and return types have been rationalised so there are only two types ("String", "StringList") with many subtypes eg. "FileIn" becomes "String (FileIn, ...)".

The appliance disk image can now be in formats other than raw (Pavel Butsykin).

Multiple improvements to how we automatically build Debian templates for virt-builder (Pino Toscano). Enable serial console for these templates (Florian Klink).

In the daemon, instead of making a private copy of lvm.conf and modifying it (eg for filters), start with an empty file since LVM understands that to mean "all defaults" (Alasdair Kergon, Zdenek Kabelac).

The "direct" backend can now run QMP queries against the QEMU binary, enhancing the kinds of information we can detect. In addition the code to query QEMU has been made more robust for handling multiple parallel queries of different versions of QEMU.

OCaml Augeas bindings are bundled under common/mlaugeas. The long term plan is to remove this and use system ocaml-augeas when it is more widely available in distros (Pino Toscano).

All OCaml modules ("*.ml" files) are now required to have an interface file ("*.mli"). If they don't export anything then the interface will be empty except for comments.

Certain OCaml features in OCaml ≥ 4.01 are used throughout the code, including replacing ‘{ field = field }’ with ‘{ field }’.

Virt-builder "make-template" utility now uses the "virt-install --transient" option so that we should never need to clean up left over domains after a crash. It also saves kickstarts and virt-install commands, which are committed to git for future reference.

/dev/shm is now created in the appliance (Nicolas Hicher).

In verbose mode on Fedora guests, virt-customize will now use "dnf --verbose" enabling better debugging output.

Virt-v2v input and output classes now contain a "#precheck" method which is used to perform environmental checks before conversion starts.

Virt-p2v enables miniexpect debugging. It is written to stderr (of virt-p2v).

Virt-v2v free space checks are more liberal especially for smaller guests (Pino Toscano).

Bugs fixed
Example URI of "Convert from ESXi hypervisor over SSH to local libvirt" is incorrect in v2v man page
virt-customize segfaults after upgrading to 1.37.35-3
Libguestfs Perl bindings can leak a small amount of memory on error
libguestfs Lua bindings use strerror(), which isn’t thread safe
man page makes no mention of using '--' when trying to change exit on error behavior
virt-df displays zeros for filesystems with block size =512
v2v should improve the result when convert a rhel7.4 guest with no available kernels found in the bootloader
virt-v2v fails with "unsupported configuration: shared access for disk 'sdb' requires use of supported storage format"
Mere presence of QEMU file locking options breaks NBD (Block protocol 'nbd' doesn't support the option 'locking')
./configure --disable-ocaml breaks building common/mlpcre which breaks building daemon
[RFE]Should update some vddk info in v2v man page
virt-v2v: warning: ova disk has an unknown VMware controller type (20)
virt-v2v '-i ova' is not parsing the MAC address from the source OVF
virt-builder fails to parse repo file if it has blank space after the repository identifier
Failed to convert the rhel5 guest with kmod-xenpv installed from xen server by virt-v2v
qemu-kvm fails to open qcow2 files in read-only mode with qemu-kvm 1.5.3
Error info shows wrong sometimes when ssh to conversion server using non-root user with sudo on p2v client
/dev/shm does not exist in the appliance environment
guestfish cannot list commands from interactive mode
Unbound constructor Hivex.OPEN_UNSAFE
bump debian images to use single-partition layout
virt-resize failed to expand swap partition for RHEL5.11 guest image with "parsing UUID failed"
Running file API on a special chardev may hang forever
inspect-os report error: could not parse integer in version number: V7Update2
[RFE]Add warning in process of v2v converting guest which has pci passthrough device
virt-v2v fails on opensuse 13.2 guest with error: statns: statns_stub: path must start with a / character
firstboot scripts are not correctly installed in Fedora 26
Libguestfs should pass copyonread flag through to the libvirt XML
1.36.x build failure: gtkdocize fails using newer autotools due to missing GTK_DOC_CHECK in
guestfs_shutdown hangs if main process sets signal handlers
guestfs_add_domain_argv fails with readonly option when vdi/vhd disk is attached to libvirt domain
RFE: Virt-v2v can't convert the guest which has encrypted partition
document URI format for -a parameters of tools
RFE: Support multicore decompression for OVA files using pigz and pxz
Win 2016 guest is described as Win 10 after imported to RHEVM
RFE: ability to convert VMware virtual machines via vmx
Please drop or update GnuPG (1.4.x) dependency
[RFE] Install Windows virtio-rng drivers on VMs imported
virt-inspector can't get icon info from altlinux-centaurus
policycoreutils setfiles >= 2.6 does .. nothing
Windows 8 UEFI from VMware to KVM fails to boot after conversion
There is error info about "No such file or directory" when convert a guest from ova file by v2v
virt-dib should generate sha256 checksum instead of sha512
RFE: OVMF should be detected on conversion server to prevent failed conversion
Should rename network name of rhv in virt-v2v man page
virt-sysprep should remove DHCP_HOSTNAME
QEMU image file locking (libguestfs)
[Debian] Missing db_dump abort inspection
Segmentation fault when reading corrupted path with Python 3 bindings
RFE: virt-p2v should support mnemonic operations
There is virt-v2v warning about <listen type='none'> during converting a guest which has listen type='none' in XML
qemu-system-s390x: -device isa-serial,chardev=charserial0,id=serial0: 'isa-serial' is not a valid device model name
selinux relabel fails on RHEL 6.2 guests with "libguestfs error: selinux_relabel: : Success"
Missing bash completion scripts for: virt-diff guestunmount virt-copy-in virt-copy-out virt-customize virt-get-kernel virt-p2v-make-disk virt-p2v-make-kickstart virt-tar-in virt-tar-out virt-v2v-copy-to-local virt-win-reg
RFE: virt-sysprep does not utilize libguestfs encryption support
[RFE]virt-v2v failed to convert VMware ESX VM with snapshot
Modify a file in virt-rescue with vi on some linux terminal such as yakuake, can lead to abnormal display in virt-rescue shell
Remove "If reporting bugs, run virt-v2v with debugging enabled .." message when running virt-p2v
Can not end a running command in virt-rescue by press ^C or other keys, the only way is to exit virt-rescue


guestfs-examples(1), guestfs-faq(1), guestfs-performance(1), guestfs-recipes(1), guestfs-testing(1), guestfs(3), guestfish(1),


Richard W.M. Jones


Copyright (C) 2009-2023 Red Hat Inc.


This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


To get a list of bugs against libguestfs, use this link:

To report a new bug against libguestfs, use this link:

When reporting a bug, please supply:

  • The version of libguestfs.
  • Where you got libguestfs (eg. which Linux distro, compiled from source, etc)
  • Describe the bug accurately and give a way to reproduce it.
  • Run libguestfs-test-tool(1) and paste the complete, unedited output into the bug report.
2023-02-21 libguestfs-1.50.1