Linux: Processor Compatibility Modes Processor Compatibility Modes

IBM

Linux Processor compatibility modes

IBM

Linux Processor compatibility modes Note Before using this information and the product it supports, read the information in “Notices” on page 5.

First Edition (September 2012) © Copyright IBM Corporation 2012. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents

Processor compatibility modes..... 1 Online version...... 4 Compatibility modes on supported servers .... 1 Live partition mobility for Power Systems servers .. 1 Notices ...... 5 Compatibility modes and specific Linux distributions 2 Trademarks ...... 6 Determining processor type and compatibility mode 3

With PowerLinux™ processor compatibility modes, you can run operating system versions that use all the standard features of a previous generation of POWER® processor.

A processor compatibility mode is a value that is assigned to a logical partition by the hypervisor. It specifies the processor environment in which the logical partition can successfully operate.

You can run several versions of Power Systems™ servers. Sometimes older versions of these operating environments do not support the capabilities that are available with new processors, thus limiting your flexibility to move logical partitions between servers that have different processor types. Support for new processors is typically added only to new Linux distribution releases.

You can move logical partitions between servers that have different processor types without upgrading the operating environments that are installed in the logical partitions. When you move a logical partition to a destination server that has a different processor type from the source server, the processor compatibility mode enables that logical partition to run in a processor environment on the destination server. The processor compatibility mode enables the destination server to provide the logical partition with a subset of processor capabilities that are supported by the operating environment that is installed in the logical partition.

You can determine processor compatibility mode in advance and at run time. In addition, you can optimize applications for performance and to benefit from processing features available only on some processors.

Compatibility modes on supported servers You can run a processor in a compatibility mode on supported servers.

On an unmanaged server, a processor that is running in a compatibility mode is compatible with a previously released processor architecture. On a managed server, a processor compatibility mode specifies the processor environment in which a logical partition can successfully operate. While POWER6 and POWER6+ are distinct LPAR processor compatibility mode settings, Linux distribution kernels operate the same in these modes. However, compilers and applications can use more instructions in the POWER6+ mode that are not available in the POWER6 mode.

For more information about processor compatibility modes, see Processor compatibility modes (http://www.ibm.com/support/knowledgecenter/POWERLINUX/p7hc3l/iphc3ivmpcm.htm) in the Systems Hardware Knowledge Center. This link leads to information whose navigation suggests it pertains to only the IVM (Integrated Virtualization Manager) style of system management. However, processor compatibility modes is a concept more fundamental than system management style. This information applies equally to the HMC (Hardware Management Console) management style. In addition, the link leads to information for a specific system that contains a POWER7® processor. However, newer architecture information includes information about processor compatibility modes for previous architectures.

Live partition mobility for Power Systems servers You can use live partition mobility to move Linux logical partitions from one system to another.

For more information about live partition mobility, see the topic corresponding to your system:

© Copyright IBM Corp. 2012 1 POWER5 systems Partition mobility (http://www.ibm.com/support/knowledgecenter/POWER5/iphc3_p5/ iphc3kickoff.htm) POWER6® systems Live Partition Mobility (http://www.ibm.com/support/knowledgecenter/POWER6/iphc3/ iphc3kickoff.htm) POWER7 systems Live Partition Mobility (http://www.ibm.com/support/knowledgecenter/POWER7/p7hc3/ iphc3kickoff.htm) IBM® PowerLinux systems Live Partition Mobility (http://www.ibm.com/support/knowledgecenter/POWERLINUX/ p7hc3l/iphc3kickoff.htm) POWER8® systems Live Partition Mobility (http://www.ibm.com/support/knowledgecenter/8247-22L/p8hc3/ p8hc3_kickoff.htm)

Compatibility modes and specific Linux distributions Processor compatibility modes vary by Linux distribution and version.

The following table describes processor compatibility modes supported by specific versions of Linux distributions. By default, a distribution kernel directs the hypervisor to run the processor in the highest mode that the distribution supports. Table 1. Processor compatibility modes supported by specific versions of Linux distributions POWER6 in POWER6 in POWER7 in POWER7 in POWER5 POWER6 mode POWER5 mode POWER7 mode POWER6 mode SUSE Linux No No No No No Enterprise Server 12, and subsequent service packs SUSE Linux Yes Yes Yes Yes Yes Enterprise Server 11 SP1, and subsequent service packs SUSE Linux Yes Yes Yes No Yes Enterprise Server 11 SUSE Linux Yes Yes Yes No Yes Enterprise Server 10 SP2, and subsequent service packs Red Hat No No No Yes No Enterprise Linux 7, and subsequent updates

2 Linux: Processor compatibility modes Table 1. Processor compatibility modes supported by specific versions of Linux distributions (continued) POWER6 in POWER6 in POWER7 in POWER7 in POWER5 POWER6 mode POWER5 mode POWER7 mode POWER6 mode Red Hat No Yes No Yes Yes Enterprise Linux 6.1, and subsequent updates Red Hat Yes Yes Yes No Yes Enterprise Linux 5.2, and subsequent updates Ubuntu 14.04, No No No No No and subsequent updates

Table 2. Processor compatibility modes supported by specific versions of Linux distributions on POWER8 systems Linux distributions running in guests on a POWER8 host POWER8 in POWER8 mode POWER8 in POWER7 mode SUSE Linux Enterprise Server 12, and Yes No subsequent service packs SUSE Linux Enterprise Server 11 SP4, Yes Yes and subsequent service packs Red Hat Enterprise Linux 6.5, and No Yes subsequent updates Red Hat Enterprise Linux 7, and Yes Yes, for big endian subsequent updates (No for Red Hat No, for little endian Enterprise Linux 7.1, little endian) Ubuntu 14.04, and subsequent Yes No updates

Note: For compatibility purposes, POWER7 and POWER7+™ are the same. All entries for POWER7 listed also apply to POWER7+.

For more information about Linux distribution support of specific hardware, see Supported Linux distributions for PowerLinux servers (http://publib.boulder.ibm.com/infocenter/lnxinfo/v3r0m0/topic/ liaam/liaamdistros.htm).

Determining processor type and compatibility mode You can determine the actual processor type and processor compatibility mode.

PowerLinux servers have processors that can run either to the full extent of their capabilities, or with capabilities compatible with a previously released processor. When a processor runs with capabilities compatible with a previous processor architecture, it is said to be running in compatibility mode.

To display the actual processor type and processor compatibility mode, run the following command: LD_SHOW_AUXV=1 /bin/true | grep _PLATFORM

The following is an example of output from this command:

Processor compatibility modes 3 AT_BASE_PLATFORM:power7 AT_PLATFORM: power6

The following fields are shown: AT_BASE_PLATFORM Actual processor type AT_PLATFORM Processor compatibility mode

The output in the example indicates that the processor is a POWER7 processor that is running in POWER6 compatibility mode. The AT_PLATFORM and AT_BASE_PLATFORM fields provide information relevant to Live partition mobility for specific systems. For more information about how this information is obtained and its significance to library optimization, see Optimized Libraries.

Online version You can view the online version of this document in the IBM Information Center for Linux.

To view the online version, click Processor compatibility modes (http://www.ibm.com/support/ knowledgecenter/linuxonibm/liacd/liacd-kickoff.htm).

4 Linux: Processor compatibility modes Notices

This information was developed for products and services offered in the U.S.A.

IBM may not offer the products, services, or features discussed in this document in other countries. Consult your local IBM representative for information on the products and services currently available in your area. Any reference to an IBM product, program, or service is not intended to state or imply that only that IBM product, program, or service may be used. Any functionally equivalent product, program, or service that does not infringe any IBM intellectual property right may be used instead. However, it is the user's responsibility to evaluate and verify the operation of any non-IBM product, program, or service.

IBM may have patents or pending patent applications covering subject matter described in this document. The furnishing of this document does not grant you any license to these patents. You can send license inquiries, in writing, to:

IBM Director of Licensing IBM Corporation North Castle Drive Armonk, NY 10504-1785 U.S.A.

The following paragraph does not apply to the United Kingdom or any other country where such provisions are inconsistent with local law: INTERNATIONAL BUSINESS MACHINES CORPORATION PROVIDES THIS PUBLICATION "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Some states do not allow disclaimer of express or implied warranties in certain transactions, therefore, this statement may not apply to you.

This information could include technical inaccuracies or typographical errors. Changes are periodically made to the information herein; these changes will be incorporated in new editions of the publication. IBM may make improvements and/or changes in the product(s) and/or the program(s) described in this publication at any time without notice.

Licensees of this program who wish to have information about it for the purpose of enabling: (i) the exchange of information between independently created programs and other programs (including this one) and (ii) the mutual use of the information which has been exchanged, should contact:

IBM Corporation Dept. LRAS/Bldg. 903 11501 Burnet Road Austin, TX 78758-3400 U.S.A.

Such information may be available, subject to appropriate terms and conditions, including in some cases, payment of a fee.

The licensed program described in this document and all licensed material available for it are provided by IBM under terms of the IBM Customer Agreement, IBM International Program License Agreement or any equivalent agreement between us.

IBM World Trade Asia Corporation Licensing 2-31 Roppongi 3-chome, Minato-ku Tokyo 106-0032, Japan

IBM may use or distribute any of the information you supply in any way it believes appropriate without incurring any obligation to you.

Information concerning non-IBM products was obtained from the suppliers of those products, their published announcements or other publicly available sources. IBM has not tested those products and cannot confirm the accuracy of performance, compatibility or any other claims related to non-IBM products. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products.

Any references in this information to non-IBM Web sites are provided for convenience only and do not in any manner serve as an endorsement of those Web sites. The materials at those Web sites are not part of the materials for this IBM product and use of those Web sites is at your own risk.

This information contains examples of data and reports used in daily business operations. To illustrate them as completely as possible, the examples include the names of individuals, companies, brands, and products. All of these names are fictitious and any similarity to the names and addresses used by an actual business enterprise is entirely coincidental.

Trademarks IBM, the IBM logo, and ibm.com are trademarks or registered trademarks of International Business Machines Corp., registered in many jurisdictions worldwide. Other product and service names might be trademarks of IBM or other companies. A current list of IBM trademarks is available on the Web at “Copyright and trademark information” at www.ibm.com/legal/copytrade.shtml.

Adobe, the Adobe logo, PostScript, and the PostScript logo are either registered trademarks or trademarks of Adobe Systems Incorporated in the United States, and/or other countries.

Linux is a registered trademark of Linus Torvalds in the United States, other countries, or both.

Microsoft, Windows, Windows NT, and the Windows logo are trademarks of Microsoft Corporation in the United States, other countries, or both.

Other product and service names might be trademarks of IBM or other companies.

6 Linux: Processor compatibility modes Notices 7 IBM®

Printed in USA