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Announcing the Unbreakable Enterprise Kernel Release 5 Update 5 for Oracle Linux

Simon Coter
Senior Manager, Oracle Linux and Virtualization Product Management

The Unbreakable Enterprise Kernel (UEK) for Oracle Linux provides the latest open source innovations and key optimizations and security to enterprise cloud and on-premises workloads. It is the Linux kernel that powers Oracle Cloud and Oracle Engineered Systems such as Oracle Exadata Database Machine as well as Oracle Linux on 64-bit Intel and AMD or 64-bit Arm platforms.

UEK Release 5 does not disable any features that are enabled in RHCK. Additional features are enabled to provide support for key functional requirements and patches are applied to improve performance and optimize the kernel.

What's New?

UEK R5 Update 5 can be recognized with a release number starting with 4.14.35-2047.500.9.1.

Notable changes:

  • Page clearing optimizations. Optimizations to the code that handles page cache clearance can improve performance in KVM for large guests, which can result in much quicker start-up times; the changes are localized to Intel's next-generation Icelake server hardware platform.

  • File systems and storage include different security and bug fixes and back-ports for btrfs, CIFS, ext4, NFS, OCFS2 and XFS.

  • RDMA
    • Improvements to RDS failover/failback performance. RDS handling of failover or failback is improved, to boost performance.

    • Improved tracing on RDS for debugging. Tracepoints have been added to RDS code for support within eBPF and DTrace, to replace legacy debugging mechanisms.

    • RDMA bug fixes and optimizations. General bug fixes and optimizations from RDMA are also included in this update, including the resolution of a bug to properly handle RDMA cancel requests.

  • Security
    • securityfs interface for Secure Boot lockdown mode added. The lockdown file for the securityfs interface (/sys/kernel/security/lockdown) now allows for reading and setting the Secure Boot lockdown state.
  • Driver updates. Working in close cooperation with hardware and storage vendors, Oracle has updated several device drivers from the versions in mainline Linux 4.14.35. Further details are available on section "1.2.1 Notable Driver Features and Updates" of the Release Notes.

The Unbreakable Enterprise Kernel Release 5 Update 5 (UEK R5U5) is based on the mainline kernel version 4.14.35. Through actively monitoring upstream check-ins and collaboration with partners and customers, Oracle continues to improve and apply critical bug and security fixes to UEK R5 for Oracle Linux. This update includes several new features, added functionality, and bug fixes across a range of subsystems.

For more details on these and other new features and changes, please consult the Release Notes for the UEK R5 Update 5.

Security (CVE) Fixes

A full list of CVEs fixed in this release can be found in the Release Notes for the UEK R5 Update 5.

Supported Upgrade Path

Customers can upgrade existing Oracle Linux 7 servers using the Unbreakable Linux Network or the Oracle Linux yum server by pointing to "UEK Release 5" Yum Channel.

Software Download

Oracle Linux can be downloaded, used, and distributed free of charge and updates and errata are freely available. This allows organizations to decide which systems require a support subscription and makes Oracle Linux an ideal choice for development, testing, and production systems. The user decides which support coverage is the best for each system individually, while keeping all systems up-to-date and secure. Customers with Oracle Linux Premier Support also receive access to zero-downtime kernel updates using Oracle Ksplice.


To minimize impact on interoperability during releases, the Oracle Linux team works closely with third-party vendors that have hardware and software dependencies on kernel modules. The kernel ABI for UEK R5 will remain unchanged in all subsequent updates to the initial release.

Oracle Linux maintains full user-space compatibility with Red Hat Enterprise Linux (RHEL), which is independent of the kernel version that s running underneath the operating system. Existing applications in userspace will continue to run unmodified on the Unbreakable Enterprise Kernel Release 5 and no re-certifications are needed for RHEL certified applications.

About Oracle Linux

Oracle Linux is an open and complete operating environment that helps accelerate digital transformation. It delivers leading performance and security for hybrid and multi cloud deployments. Oracle Linux is 100% application binary compatible with Red Hat Enterprise Linux. And, with an Oracle Linux Support subscription, customers have access to award-winning Oracle support resources and Linux support specialists, zero-downtime patching with Ksplice, cloud native tools such as Kubernetes and Kata Containers, KVM virtualization and Oracle Linux Virtualization Manager, DTrace, clustering tools, Oracle Linux Manager, Oracle Enterprise Manager, and lifetime support. All this and more is included in a single cost-effective support offering. Unlike many other commercial Linux distributions, Oracle Linux is easy to download and completely free to use, distribute, and update.

Further information available at oracle.com/linux .

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