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Announcing the general availability of the Unbreakable Enterprise Kernel Release 5 Update 2

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 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 any Intel-64, AMD-64 or ARM hardware.

What's New?

UEK R5 Update 2 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 the Unbreakable Enterprise Kernel (UEK) R5 for Oracle Linux. This update includes several new features, added functionality, and bug fixes across a range of subsystems.

Notable changes:

  • Pressure Stall Information (PSI) patchset implemented. PSI is designed to help system administrators maximize server resources and can be used to pinpoint and troubleshoot resource utilization issues.
  • Implementation of the ktask framework for parallelizing CPU-intensive workThe ktask framework parallelizes CPU-intensive work in the kernel. This helps improve performance by harnessing idle CPUs, to complete jobs more quickly.
  • DTrace support for libpcap packet capture. Kernel and userspace updates enable support for libpcap-based packet capture in DTrace.
  • File system and storage fixes. Fixes to btrfs, CIFS, ext4, OCFS2, and XFS file systems.
  • Virtualization features and updates. Upstream improvements from the 4.19 kernel for KVM, Xen, and Hyper-V, including major updates and security fixes for KVM; numerous security fixes and code enhancements for Hyper-V; fix for the Xen blkfront hotplug issue; and a fix for the Xen x86 guest clock scheduler.
  • Driver updates. In close cooperation with hardware and software vendors, several device drivers have been updated.
  • Kernel tuning dedicated to the Arm platform. Further kernel tuning for Arm platforms and parameters for unsupported hardware have been disabled, to improve stability and performance.
  • NVMe updates. Fixes and improvements for NVMe are included from upstream Linux kernel versions 4.18 through 4.21.

For more details on these and other new features and changes, please consult the Release Notes for the UEK R5 Update 2.

Security (CVE) Fixes

A full list of CVEs fixed in this release can be found in the Release Notes for the UEK R5 Update 2.

Supported Upgrade Path

Customers can upgrade existing Oracle Linux 7 Update 5 (and later) servers using the Unbreakable Linux Network or the Oracle Linux yum server.

Software Download

Oracle Linux can be downloaded, used, and distributed free of charge and all 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.


UEK R5 Update 2 is fully compatible with the UEK R5 GA release. The kernel ABI for UEK R5 remains unchanged in all subsequent updates to the initial release. UEK R5 includes changes to the kernel ABI relative to UEK R4 that require recompilation of third-party kernel modules.

About Oracle Linux

The Oracle Linux operating system is engineered for an open cloud infrastructure. It delivers leading performance, scalability and reliability for enterprise SaaS and PaaS workloads as well as traditional enterprise applications. Oracle Linux Support offers access to award-winning Oracle support resources and Linux support specialists; zero-downtime updates using Ksplice; additional management tools such as Oracle Enterprise Manager and Spacewalk; and lifetime support, all at a low cost. And unlike many other commercial Linux distributions, Oracle Linux is easy to download, completely free to use, distribute, and update.
Oracle tests the UEK intensively with demanding Oracle workloads, and recommends the UEK for Oracle deployments and all other enterprise deployments.

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