SUSE Linux Enterprise Real Time 15 SP6

Release Notes

Abstract

SUSE Linux Enterprise Real Time is an integrated suite of robust open source
real-time technologies that enable enterprises to implement solutions with
controlled response times. This document gives an overview of features of SUSE
Linux Enterprise Real Time and their limitations.

These release notes will be updated periodically, and the latest version of
these release notes is always available at https://www.suse.com/releasenotes.

General documentation can be found at https://documentation.suse.com/sle-rt/
15-SP6/.

Publication Date: 2024-02-28, Version: 15.6.20240228

1 About the release notes
2 SUSE Linux Enterprise Real Time
3 Installation
4 Obtaining source code
5 Legal notices

1 About the release notes

These Release Notes are identical across all architectures, and the most recent
version is always available online at https://www.suse.com/releasenotes.

Entries are only listed once but they can be referenced in several places if
they are important and belong to more than one section.

Release notes usually only list changes that happened between two subsequent
releases. Certain important entries from the release notes of previous product
versions are repeated. To make these entries easier to identify, they contain a
note to that effect.

However, repeated entries are provided as a courtesy only. Therefore, if you
are skipping one or more service packs, check the release notes of the skipped
service packs as well. If you are only reading the release notes of the current
release, you could miss important changes.

2 SUSE Linux Enterprise Real Time

SUSE Linux Enterprise Real Time is an integrated suite of robust open source
real-time technologies that enable enterprises to implement solutions with
controlled response times. SUSE Linux Enterprise Real Time enables usage of
SUSE Linux Enterprise Server based technologies in environments where having
control over latencies is a critical requirement. Its open source license
minimizes the risk of vendor lock-in, and its adherence to open standards
encourages interoperability with industry standard tools and technologies.

2.1 What is new?

SUSE Linux Enterprise Real Time 15 SP6 introduces changes compared to SUSE
Linux Enterprise Real Time SP5. The most important changes are listed below:

  o The kernel has inherited hardware enablement and part of new features of
    SUSE Linux Enterprise Server 15 SP6 kernel.

  o The latest stable 6.4 PREEMPT_RT has been incorporated into the service
    pack.

  o Certifications Module and Containers Module have been enabled and become an
    option in SUSE Linux Enterprise Real Time 15 SP6.

  o Live Patching Extension has been enabled and become an option in SUSE Linux
    Enterprise Real Time 15 SP6.

  o Package Hub Module has been enabled and become an option in SUSE Linux
    Enterprise Real Time 15 SP6.

  o LTTng tools package has been updated to version 2.13.11 and moved to the
    Development Tools Module 15 SP6. SUSE Linux Enterprise Real Time 15 SP6
    carries kernel module packages needed for operation of LTTng, and LTTng
    Userspace Tracing has been fully enabled in the product.

  o Support for Precision Time Protocol version 2 continues to be available
    through the base SUSE Linux Enterprise Server 15 SP6 product.

  o RT-Tests suite has been updated to version 2.5, and contains programs to
    test various real time Linux features.

  o Cpuset has been updated to version 1.6.1. It allows manipulation of cpusets
    on the system and provides higher level functions such as implementation
    and control of a basic CPU shielding setup.

  o Previously, SUSE Linux Enterprise Real Time only disabled lower C-states in
    the kernel config. However, starting from SUSE Linux Enterprise Real Time
    15 SP6 all C-states are now disabled.

2.1.1 Enriched system visibility in the SUSE Customer Center (SCC)

SUSE is committed to helping provide better insights into the consumption of
SUSE subscriptions regardless of where they are running or how they are
managed; physical or virtual, on-prem or in the cloud, connected to SCC or
Repository Mirroring Tool (RMT), or managed by SUSE Manager. To help you
identify or filter out systems in SCC that are no longer running or
decommissioned, SUSEConnect now features a daily "ping", which will update
system information automatically.

For more details see the documentation at https://documentation.suse.com/
subscription/suseconnect/single-html/SLE-suseconnect-visibility/.

2.2 Hardware Platform Support

SUSE Linux Enterprise Real Time 15 SP6 only supports Intel 64/AMD64 (x86-64)
platform.

2.3 Technology Previews

Technology previews are packages, stacks, or features delivered by SUSE which
are not supported. They may be functionally incomplete, unstable or in other
ways not suitable for production use. They are included for your convenience
and give you a chance to test new technologies within an enterprise
environment.

Whether a technology preview becomes a fully supported technology later depends
on customer and market feedback. Technology previews can be dropped at any time
and SUSE does not commit to providing a supported version of such technologies
in the future.

Give your SUSE representative feedback about technology previews, including
your experience and use case.

2.3.1 Technology Previews for scheduling

  o SUSE Linux Enterprise Real Time 15 SP6 enables the SCHED_DEADLINE
    scheduling class as a Technology Preview (best-effort support). This
    scheduler predicts task scheduling based on application deadlines, which is
    particularly useful for realtime workload.

2.3.2 Technology Previews for Virtualization Support

  o Guests for non-realtime sensitive workloads.

  o Docker containers and real-time capabilities.

  o Realtime-sensitive workloads guests. This means that you can install both
    RT and non-RT VM on a single machine. With proper system settings and
    application analysis, RT and non-RT guests can co-exist without affecting
    each other.

2.4 Limitations

Normally, the RT deadlines and constraints are defined by the application, not
the OS itself. If an application cannot tolerate any interference or if it's
just barely making it's deadlines, then live patching may cause the deadline to
be missed. It doesn't matter if live patching takes 1 microsecond or 1 second
to complete if it causes the application to exceed its time budget.

At least the below three situations have to be taken into an account:

  o Live patching of a process that is not running in the kernel right now.

  o Overhead of the patched function

  o Impact to a task running within the kernel at the time of patching

2.5 Documentation and other information

2.5.1 Available on the product media

  o Read the READMEs on the media.

  o Get the detailed change log information about a particular package from the
    RPM (where FILENAME.rpm is the name of the RPM):

    rpm --changelog -qp FILENAME.rpm

  o Check the ChangeLog file in the top level of the installation medium for a
    chronological log of all changes made to the updated packages.

  o Find more information in the docu directory of the installation medium of
    SUSE Linux Enterprise Real Time 15 SP6. This directory includes PDF
    versions of the SUSE Linux Enterprise Real Time 15 SP6 Installation Quick
    Start Guide.

  o Get list of manual pages with usage information about a particular package
    from the RPM (where FILENAME.rpm is the name of the RPM):

    rpm --docfiles -qp FILENAME.rpm | grep man

2.5.2 Online documentation

  o For the most up-to-date version of the documentation for SUSE Linux
    Enterprise Real Time 15 SP6, see https://documentation.suse.com/sle-rt/
    15-SP6/.

  o Find a collection of White Papers in the SUSE Linux Enterprise Real Time
    Resource Library at https://www.suse.com/products/realtime/.

For more information, check our Support Policy page https://www.suse.com/
support/policy.html or the Long Term Service Pack Support Page https://
www.suse.com/support/programs/long-term-service-pack-support.html.

2.6 Support statement for SUSE Linux Enterprise Real Time

To receive support, you need an appropriate subscription with SUSE. For more
information, see https://www.suse.com/support/programs/subscriptions/?id=
SUSE_Linux_Enterprise_Server.

The following definitions apply:

L1

    Problem determination, which means technical support designed to provide
    compatibility information, usage support, ongoing maintenance, information
    gathering and basic troubleshooting using available documentation.

L2

    Problem isolation, which means technical support designed to analyze data,
    reproduce customer problems, isolate problem area and provide a resolution
    for problems not resolved by Level 1 or prepare for Level 3.

L3

    Problem resolution, which means technical support designed to resolve
    problems by engaging engineering to resolve product defects which have been
    identified by Level 2 Support.

For contracted customers and partners, SUSE Linux Enterprise Real Time is
delivered with L3 support for all packages, except for the following:

  o Technology Previews, see Section 2.3, "Technology Previews"

  o Sound, graphics, fonts and artwork

  o Packages that require an additional customer contract, see Section 2.6.2,
    "Software requiring specific contracts"

  o Some packages shipped as part of the module Workstation Extension are
    L2-supported only

  o Packages with names ending in -devel (containing header files and similar
    developer resources) will only be supported together with their main
    packages.

SUSE will only support the usage of original packages. That is, packages that
are unchanged and not recompiled.

2.6.1 General support

To learn about supported features and limitations, refer to the following
sections in this document:

  o Section 2.2, "Hardware Platform Support"

2.6.2 Software requiring specific contracts

Certain software delivered as part of SUSE Linux Enterprise Real Time may
require an external contract. Check the support status of individual packages
using the RPM metadata that can be viewed with rpm, zypper, or YaST.

Major packages and groups of packages affected by this are:

  o PostgreSQL (all versions, including all subpackages)

2.6.3 Software under GNU AGPL

SUSE Linux Enterprise Real Time 15 SP6 (and the SUSE Linux Enterprise modules)
includes the following software that is shipped only under a GNU AGPL software
license:

  o Ghostscript (including subpackages)

SUSE Linux Enterprise Real Time 15 SP6 (and the SUSE Linux Enterprise modules)
includes the following software that is shipped under multiple licenses that
include a GNU AGPL software license:

  o MySpell dictionaries and LightProof

3 Installation

This section includes information related to the initial installation of SUSE
Linux Enterprise Real Time 15 SP6.

For installation documentation, see section 2 of the Setup Guide at https://
documentation.suse.com/sle-rt/15-SP6/single-html/SLE-RT-setup/#article-setup

3.1 Real Time kernel not selected as default

Due to the way kernels are sorted, the Real Time kernel might not be selected
as the default one after installation. You can use YaST to select the default
kernel.

4 Obtaining source code

This SUSE product includes materials licensed to SUSE under the GNU General
Public License (GPL). The GPL requires SUSE to provide the source code that
corresponds to the GPL-licensed material. The source code is available for
download at https://www.suse.com/download/sle-rt/ on Medium 2. For up to three
years after distribution of the SUSE product, upon request, SUSE will mail a
copy of the source code. Send requests by e-mail to sle_source_request@suse.com
. SUSE may charge a reasonable fee to recover distribution costs.

5 Legal notices

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