GUESTFS-RELEASE-NOTES-1.38(1)

📦
version 1.61.3 · 14 versions
, in centos-stream 10

💖 NAME 💖

Okay bestie, this is guestfs-release-notes — the libguestfs Release Notes, and you’re looking at the guestfs-rel...-notes-1.38(1) page from the Virtualization Support section. It’s giving official docs but make it make sense. 🫶

🌈 RELEASE NOTES FOR LIBGUESTFS 1.38 🌈

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 — a brand-new tool allowing end users to create and update virt-builder repositories (Cédric Bosdonnat). Obsessed.
  • virt-rescue — okay so it’s not a new tool, but it has been substantially rewritten, implementing job control, -m and -i options, escape keys, etc. Literally a glow-up.

🧰 New features in existing tools

  • Virt-builder planner — 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, they’re now installed under multi-user.target instead of default.target, 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

  • Fixed multiple memory leaks and other data corruption problems in the Java bindings (Pino Toscano).
  • Perl %guestfs_introspection has been dropped. RIP.

🔍 Inspection

  • 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.

🌟 Other

  • 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.

🔒 Security

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. 💀

🧩 API

🆕 New APIs

  • hivex_value_string — this replaces the deprecated hivex_value_utf8 API, but does the same thing.
  • part_get_gpt_attributes, part_set_gpt_attributes — read and write GPT partition attribute flags (Cédric Bosdonnat).
  • part_resize — enlarge or shrink an existing partition (Nikos Skalkotos).
  • yara_destroy, yara_load, yara_scan — 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).

🧚 Internals

  • 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).

okay so, all OCaml modules (*.ml files) are now required to have an interface file (*.mli). If a module doesn’t export anything, that interface file will be empty except for comments — and honestly, sometimes that’s the whole vibe. 💅

Certain OCaml features in OCaml ≥ 4.01 are used throughout the code, including replacing { field = field } with { field }. the way that little shortcut ate, no cap. ✨

Virt-builder make-template utility now uses the virt-install --transient option, so 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. archival queen behavior, fr fr. 🎀

/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. lowkey a debugging glow-up. 🔥

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

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). generous icon behavior. 🌸

💀 Bugs fixed 💀

okay bestie, this is the bug-fix roll call and every single link is staying. periodt. 🐞

👀 SEE ALSO 👀

like, go read these next, bestie — they’re the companion lore:

✍️ AUTHOR ✍️

the one and only Richard W.M. Jones 👑💖

Copyright (C) 2009-2025 Red Hat Inc.

📜 LICENSE 📜

okay legal bestie, here’s the exact license text and we are not touching the words:

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.

🐞 BUGS 🐞

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

https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools

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

https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools

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.

💅 that’s the end — this page is libguestfs-1.61.3, dated 2026-09-16. now go be iconic and file those bugs with receipts. 💖

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