How to enable NX GZIP support in Red Hat Enterprise Linux 8

Solution In Progress - Updated -

Environment

  • Red Hat Enterprise Linux 8 and above
  • PowerPC architecture

Issue

  • How do I enable NX GZIP acceleration in Red Hat Enterprise Linux 8?
  • The nx-crypto kernel module is missing Red Hat Enterprise Linux 8

Resolution

  • For physical systems running on Power 9, make sure the kernel is updated to at least kernel-4.18.0-240.el8 or above as per errata RHSA-2020:4431
  • For Red Hat Enterprise Linux 8 virtual machines hosted on PowerPC 0 via PowerVM, please follow this knowledge-base article or engage your respective Red Hat support representative for updates on a private bugzilla report tracking the progress of this feature inclusion.

Root Cause

  • Access to IBM Nest Acceleration (NX) cryptography was reworked between Red Hat Enterprise Linux 7 and 8 in an effort to take advantage of Power9's new Virtual Accelerator Switchboard (VAS).
  • NX engines, which provide cryptographic capabilities and decompression/compression capabilities within the CPU itself, has been in Power processors since Power7+, but access to the NX engines was through the icswx instruction which is only available to the kernel/hypervisor. This means cryptographic and compression/decompression accelerations provided via NX was still limited in performance by context switching from userspace to kernelspace.
  • Starting with Power9, access to the NX engines is provided to both kernel and user space processes directly through VAS. In Red Hat Enterprise Linux 7 and below, access to the NX accelerators were handled via a variety of kernel modules such as nx-crypto via the icswx instruction.
  • For more information on VAS and the Linux patches in question, please refer to the following external links;

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