XCAT_2.18_Release_Notes

xCAT 2.18 Release Notes (June 22, 2026)

xCAT 2.18.0 was released on June 22, 2026. This release brings full support for Enterprise Linux 10 (RHEL 10 / AlmaLinux 10) on x86_64, along with a large set of provisioning, networking, and BMC reliability fixes.

Operating System Support

This release adds support for EL10

• RHEL/Alma 10.1 (x86_64)

Complete OS support details are available in the xCAT2 Release Information and the Compute node support matrix documentation.

Only EL10 packages are being provided as part of this release but this was a major update the underlying depencies xCAT uses, our goal is to support the following targets

Platform	Arch
EL9	x86_64, ppc64le
EL10	x86_64, ppc64le
Ubuntu 22.04 LTS	x86_64, ppc64el
Ubuntu 24.04 LTS	x86_64, ppc64el
Ubuntu 26.04 LTS	x86_64, ppc64el

Highlighted Changes

Modernizing the dependencies

xCAT 2.18 is a large modernization pass to bring xCAT onto current Enterprise Linux 10 toolchains and runtime components:

• OpenSSL 3.0 — certificate and host-key generation updated for OpenSSL 3.x.
• systemd — replace SysV init scripts/calls with their systemd counterparts.
• NetworkManager / nmcli — replace legacy network-scripts (ifcfg-*) handling with NetworkManager/nmcli.
• Net::DNS ≥ 1.36 and bind ≥ 9.18 — makedns/DDNS reworked for the TSIG signing API change introduced in Net::DNS 1.36 and for modern bind.
• DHCP backend split — Kea vs ISC — site.dhcpbackend=auto now selects the backend per platform:
  • Kea on EL ≥ 10, Ubuntu 22.04 LTS, and newer releases
  • ISC DHCP on EL ≤ 9, Ubuntu 20.04 LTS, and older releases
  • explicit isc / kea overrides remain for development and troubleshooting; Kea config rendering is version-aware (Kea 2.4 vs 3.x).
  • dhcp-* packages are still available in xcat-dep repository in case we need to fallback to ISC implementation. They should be removed in the next releases. xcat-core packages do not depend on they anymore, they were using during the start of the EL10 porting, but now are completely replaced by Kea DHPC server.
• Dracut 105 module format — genesis dracut modules upgraded to the dracut 105+ module-setup.sh format (new dracut_105/ module set for EL and Ubuntu; the legacy install.ubuntu script is deprecated).
• mock for RPM builds — RPMs are now built in clean mock chroots across multiple EL targets via the new buildrpms flow (with local-repo mode and automated dependency installation).
• dnf — use dnf for EL8+ Red Hat genimage installroot and detect dnf as the package manager in ospkgs/otherpkgs postscripts.
• grub2 — replace yaboot with grub2 for genesis and node discovery (x86_64 and ppc64le).
• xcat-dep — Built automated and modernized
  • perl-Sys-Virt — Update to allow linking with libvirt 11, this enable mkvm in EL10.

Provisioning & networking

• EL10 stateless netboot profiles and clone-distro symlinks for AlmaLinux 10, RHEL 10, and Oracle Linux 10 (including ppc64le); copycds copies aarch64 EFI bootloaders for cross-arch netboot.
• confignetwork: add -r to remove undefined NICs; fix the SETINSTALLNIC typo; harden handling of NetworkManager profile names containing spaces.
• Fix nicutils IPv4 address validation; add a networkd fallback for the netplan static-IP probe.
• makedhcp: remove a dead check that skipped all remote networks; error when a node IP overlaps the DHCP dynamic range.
• Configurable ISC OMAPI TSIG policy and xCAT TLS policy selection; configurable sudoerpolicy with modern credential fetch.
• Restore legacy SLES provisioning paths; guard Ubuntu live-media package sources and stop the public-mirror fallback during genimage.

BMC / IPMI / OpenBMC reliability

• Fall back from sha256 to sha1 on RAKP2 auth rejection; set the IPMI name-only lookup bit in RAKP1 to match ipmitool.
• Accept RMCP message tag 0 from OpenBMC with session-ID correlation.
• Reject IPMI packets with invalid CBC padding instead of crashing.
• Retry on HTTP 503 from the OpenBMC REST API instead of failing.
• Skip disabled IPMI user slots in bmcsetup.
• rspconfig: allow disabling VLAN on IPMI BMCs; improve SET readback and fix the backupgateway SET target.

Other fixes

• Prevent mkdef partial writes on validation errors.
• Fix xcatprobe TFTP check failure under a restrictive umask.
• Fix the csh syntax error in /etc/profile.d/xcat.csh.
• Move the kernel quiet flag from hardcoded to an osimage default.

Download xCAT

xCAT 2.18.0 for Enterprise Linux 10 is distributed as signed yum repositories:

• xcat-core: https://xcat.org/files/xcat/repos/yum/2.18/rc1/
• xcat-dep: https://xcat.org/files/xcat/repos/yum/devel/xcat-dep/rh10/x86_64/

Example /etc/yum.repos.d/xcat-core.repo:

[xcat-core]
name=xCAT 2.18 Core
baseurl=https://xcat.org/files/xcat/repos/yum/2.18/rc1/
enabled=1
gpgcheck=1
gpgkey=https://xcat.org/files/xcat/repos/yum/2.18/rc1/repodata/repomd.xml.key

Then:

dnf clean all
dnf install xCAT

Offline tarball bundles

For air-gapped installs, downloadable bundles for Enterprise Linux 10 (x86_64) are also available:

• xcat-core: https://xcat.org/files/xcat/xcat-core/2.18.x_Linux/xcat-core/xcat-core-2.18.0-linux.tar.bz2
• xcat-dep: https://xcat.org/files/xcat/xcat-dep/2.x_Linux/xcat-dep-2.18.0-linux.tar.bz2

Unpack each and run its mklocalrepo.sh to register a local repository, then dnf install xCAT.

Full Hierarchical Test

A full hierarchical cluster — management node, service node, and compute nodes — was validated end to end:

Platform	Arch	Node	Deployment
Alma 10.1	x86_64	Management	n/a
Alma 10.1	x86_64	Service	stateful
Alma 10.1	x86_64	Compute	stateful, stateless, stateless (squashfs)

DHCP Backend Tests

The DHCP backend selection (Kea vs ISC) and the PXE / UEFI / POWER boot handoff were validated across Enterprise Linux and Ubuntu releases on x86_64 and ppc64le (KVM), covering BIOS and UEFI, stateless and stateful:

Platform	Arch	DHCP backend
EL9	x86_64, ppc64le	ISC
EL10	x86_64, ppc64le	Kea 3.0.1
Ubuntu 18.04 LTS	x86_64	ISC
Ubuntu 20.04 LTS	x86_64	ISC
Ubuntu 22.04 LTS	x86_64	Kea 2.0.2
Ubuntu 24.04 LTS	x86_64, ppc64le	Kea 2.4.1
Ubuntu 26.04 LTS	x86_64	Kea 3.0.3

Documentation

Complete documentation is hosted at https://xcat-docs.readthedocs.io/.