1.1.1 64-bit Arm (aarch64) architecture

With Unbreakable Enterprise Kernel Release 5, Oracle delivers kernel modifications to enable support for 64-bit Arm (aarch64) architecture. These changes are built and tested against existing Arm hardware and provide support for Oracle Linux for Arm. Features described in this document are available for Arm insofar as the hardware is capable of supporting the feature that is described. Limitations and items beyond the scope of current development work for Arm are described in more detail in Section 3.1, “Unusable or Unavailable Features for Arm”.

Other notable Arm-specific changes that have been made in UEK R5 include:

  • 64 KB Base Page Size.  During testing the use of a 64 KB base page size resulted in significant performance gains for workloads that stress memory, such as MySQL and Java middleware, where THP (Transparent Huge Pages) are not used or the application is not configured to use huge pages. This change results in better overall performance and removes complex configuration requirements to configure huge pages manually.

  • Arm port of DTrace code.  Kernel code has been patched to facilitate an Arm (aarch64) port of DTrace on UEK R5. This includes changes to add support for aarch64 in the SDT collection process and to allow SDT to be disabled even when DTrace is enabled. Profile and systrace providers have been updated and tested to be functional on aarch64.

  • Kdump modifications.  Changes were made to kexec to ensure that the crashdump kernel runs at exception level 2 (EL2)

  • KVM patches for Arm.  A large number of Arm-related backports are included to help to enable KVM for Arm.

  • CPU topology workaround to resolve missing cache information in ACPI.  Due to lack of an official cache property for Arm64 in ACPI, the CPU cache information is not present in sysfs. To resolve this issue, a patch has been applied to display default cache information until such time that ACPI provides better information.