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{{Short description|Usage of Linux operating system on IBM mainframes}}
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{{History of IBM mainframe operating systems}}
 
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Linux on IBM Z originated as two separate efforts to port Linux to IBM's [[IBM System/390|System/390]] servers. The first effort, the "Bigfoot" project, developed by [[Linas Vepstas]] in late 1998 through early 1999, was an independent distribution and has since been abandoned.<ref>{{cite web|last=Vepstas|first=Linas|title=Linux on the IBM ESA/390 Mainframe Architecture|url=http://www.linas.org/linux/i370-bigfoot.html|access-date=5 June 2013}}</ref> IBM published a collection of patches and additions to the Linux 2.2.13 [[Kernel (operating system)|kernel]] on December 18, 1999, to start today's mainline Linux on IBM Z.<ref>{{cite web|title=Linux/390 - Notes and Observations|url=http://linuxvm.org/penguinvm/notes.html|access-date=5 June 2013}}</ref> Formal product announcements quickly followed in 2000, including the [[Integrated Facility for Linux]] (IFL) engines. [[Think Blue Linux]] was an early mainframe distribution consisting mainly of [[Red Hat]] packages added to the IBM kernel.<ref>{{cite web|title=Linux for S/390|url=http://linux.s390.org/|access-date=5 June 2013}}</ref> Commercial Linux distributors introduced mainframe editions very quickly after the initial kernel work.
 
IBM manager Karl-Heinz Strassemeyer of Böblingen in Germany was the main lead to get Linux running on S/390.<ref>{{cite web|last=Lettice|first=John|title=IBM's S/390 Linux guru on the Open Source patent question|date=19 November 2002|website=[[The Register]]|url=https://www.theregister.com/2002/11/19/ibms_s_390_linux_guru/}}</ref>
 
At the start of IBM's involvement, Linux patches for IBM ZS/390 included some ''object code only'' (OCO) modules, without source code.<ref>{{cite web|title=Kernel 2.2 based|url=http://www.ibm.com/developerworks/linux/linux390/exp-2_2_20.html|work=developerWorks|publisher=IBM|access-date=5 June 2013|archive-url=https://web.archive.org/web/20140903053127/http://www.ibm.com/developerworks/linux/linux390/exp-2_2_20.html|archive-date=3 September 2014|url-status=dead}}</ref> Soon after IBM replaced the OCO modules with [[Open-source software|open source]] modules. Linux on IBM Z is [[free software]] under the [[GNU General Public License]].
 
According to IBM, by May,{{as of|2006|5|lc=y}}, over 1,700 customers were running Linux on their mainframes; some examples are [[Nomura Securities]], [[Home Depot]], and the [[University of Pittsburgh]].<ref>{{cite web|last=Milberg|first=Ken|title=The Gen Xer's Guide to the Mainframe Part III|url=http://www.ibmsystemsmag.com/mainframe/administrator/performance/The-Gen-Xer-s-Guide-to-the-Mainframe-Part-III/|work=IBM Systems Magazine|date=July 2008|access-date=5 June 2013|archive-url=https://web.archive.org/web/20151117014024/http://www.ibmsystemsmag.com/mainframe/administrator/performance/The-Gen-Xer-s-Guide-to-the-Mainframe-Part-III/|archive-date=17 November 2015|url-status=dead}}</ref>
 
==Virtualization==
[[Hardware virtualization|Virtualization]] is required by default on IBM Z; there is no option to run Linux on IBM Z without some degree of virtualization. (Only the very first 64-bit mainframe models, the z900 and z800, included a non-virtualized "basic mode.") First layer virtualization is provided by the Processor Resource and System Manager ([[logical partition#PR/SM|PR/SM]]) to deploy one or more Logical Partitions (LPARs). Each LPAR supports a variety of operating systems including Linux on IBM Z. A [[hypervisor]] called z/VM can also be run as the second layer virtualization in LPARs. This allows an LPAR to createrun as many virtual machines (VMs) as therecan arebe supported by the resources assigned to the LPARs to support themLPAR. [[Kernel-based Virtual Machine|KVM]] on IBM Z is another hypervisor option.
 
When Linux applications in an LPAR access data and applications in other LPARs such as [[CICS]], [[IBM Db2]], [[IBM Information Management System|IMS]], [[Linux]], and other mainframe subsystems running on the same physical mainframe, they can utilize [[HiperSocket]]s &ndash; fast, memory-only [[Internet protocol suite|TCP/IP]] connections. As compared to TCP/IP over standard [[network interface controller|network interface cards]]s (NICs, also known as Open System Adapters (OSAs) in mainframes), HiperSockets can improve end-user responsiveness (reduce network latency and processing overhead), security (since there's no network connection to intercept), and reliability (since there's no network connection to lose).<ref>{{cite web|title=HiperSocketsIntroduction|url=httphttps://publib.boulderwww.ibm.com/infocenterdocs/zosnl/basics/index.jsplinux-on-systems?topic=/com.ibm.zos.znetwork/znetwork_85.htmfindings-introduction|work=z/OSExploiting basicHiperSockets skillsin informationa KVM Environment Using IP Routing with Linux on Z - Results and centerFindings|publisher=IBM|access-date=523 JuneJuly 20132024}}</ref>
 
With the zEC12, zBC12, and later models, the HiperSocket concept is extended beyond the physical machine boundary via an [[RDMA over Converged Ethernet]] (RoCE) adapter to facilitate a secure and high speed inter-system communication. Applications in LPAR A in system A can thus use HiperSockets to communicate with applications in LPAR B in system B to ensure the security and performance attributes.{{citation needed|date=August 2014}}
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Beginning with Linux kernel version 4.1 released in early 2015, Linux on IBM Z is only available as a [[64-bit computing|64-bit]] operating system compatible with [[z/Architecture]] mainframes. Previously Linux on IBM Z was also available as a [[32-bit computing|32-bit]] operating system, with [[31-bit computing|31-bit]] addressing, compatible with older model mainframes introduced prior to 2000's z900 model. However, the newer 64-bit Linux kernel and 64-bit Linux on IBM Z distributions are still backward compatible with applications compiled for 32-bit Linux on IBM Z. Historically the Linux kernel architecture designations were "s390" and "s390x" to distinguish between the 32-bit and 64-bit Linux on IBM Z kernels respectively, but "s390" now also refers generally to the one Linux on IBM Z kernel architecture.
 
Linux runs on standard, general purpose mainframe CPs (Central Processors) as well as IFLs ([[Integrated Facility for Linux]]). IFLs are mainframe processors dedicated to running Linux, either natively or under a hypervisor (z/VM or KVM on IBM Z). [[Microcode]] restricts IFLs from running "traditional" workloads, such as [[z/OS]], but they are physically identical to other IBM Z processors. IFLs are typically less expensive to acquire from IBM than CPs.<ref>{{cite web|title=IBM Z: Linux on IBM Z - Solutions - IFL|url=http://www-03.ibm.com/systems/z/os/linux/solutions/ifl.html|archive-url=https://web.archive.org/web/20080917051719/http://www-03.ibm.com/systems/z/os/linux/solutions/ifl.html|url-status=dead|archive-date=September 17, 2008|publisher=IBM|access-date=5 June 2013}}</ref>
 
Linux on IBM Z gives the flexibility of running Linux with the advantages of [[Mainframe computer|fault-tolerant mainframe hardware]] capable of over 90,000 I/O operations per second<ref>{{cite web|url=https://www.ibm.com/it-infrastructure/z/capabilities/connectivity|title=IBM Z - I/O Connectivity: FICON/zHPF/CTC|date=2012-11-15|website=www.ibm.com|language=en-US|access-date=2016-06-01|archive-url=https://web.archive.org/web/20171201182203/https://www.ibm.com/it-infrastructure/z/capabilities/connectivity|archive-date=2017-12-01|url-status=dead}}</ref> and with a [[Mean time between failures|mean time between failure (MTBF)]]<ref>{{cite web|url=http://www.computerworld.com/article/2560019/computer-hardware/mtbf.html|title=MTBF|last=staff|first=Computerworld|website=Computerworld|date=31 October 2005|access-date=2016-06-01}}</ref> measured in decades.<ref name=":0">{{cite web|url=http://www.fool.com/investing/general/2015/01/24/heres-why-ibm-is-still-building-mainframes.aspx|title=Here's Why IBM Is Still Building Mainframes -- The Motley Fool|last=Green|first=Timothy|website=The Motley Fool|date=24 January 2015|access-date=2016-06-01}}</ref> Using virtualization, numerous smaller servers can be combined onto one mainframe, gaining some benefits of centralization and cost reduction, while still allowing specialized servers. Instead of [[paravirtualization]], IBM mainframes use [[full virtualization]], which permits workload density far greater than paravirtualization does.{{citation needed|reason=Provide source for definition of workload density and relationship to paravirtualization|date=October 2018}} Combining full virtualization of the hardware plus lightweight [[Z/VM|Virtual Machine]] containers that run Linux in isolation (somewhat similar in concept to [[Docker (software)|Docker]]) result in a platform that supports more virtual servers than any other in a single footprint,<ref>{{cite web|url=httphttps://www.vm.ibm.com/overview/index.html|title=IBM: About the z/VM Operating System|date=2015-01-14|website=www.vm.ibm.com|language=EN|access-date=2016-06-01}}</ref>{{failed verification|date=October 2023}} which also can lower operating costs. Additional savings can be seen from reduced need for floor space, power, cooling, networking hardware, and the other [[Data center infrastructure management|infrastructure]] needed to support a [[data center]]. IBM mainframes allow transparent use of [[Mainframe computer|redundant processor execution steps]] and [[Mainframe computer|integrity checking]], which is important for critical applications in certain industries such as banking.{{citation needed|reason=dubiouscn|date=JuneOctober 20132023}} Mainframes typically allow [[Hot swapping|hot-swapping of hardware]], such as processors and memory. IBM Z provides fault tolerance for all key components, including processors, memory, I/O Interconnect, power supply, channel paths, network cards, and others. Through internal monitoring, possible problems are detected and problem components are designed to be switched over without even failing a single transaction.<ref>{{cite web|url=https://www.ibm.com/it-infrastructure/z/capabilities/resiliency|title=IBM Z - Business resiliency: Data Driven - Server|date=2010-10-26|website=www.ibm.com|language=en-US|access-date=2016-06-01}}</ref> In the rare event of failure, firmware will automatically enable a spare component, disable the failing component, and notify IBM to dispatch a service representative. This is transparent to the operating system, allowing routine repairs to be performed without shutting down the system. Many industries continue to rely on mainframes where they are considered to be the best option in terms of reliability, security, or cost.<ref name=":0" />▼
==Advantages==
▲Linux on IBM Z gives the flexibility of running Linux with the advantages of [[Mainframe computer|fault-tolerant mainframe hardware]] capable of over 90,000 I/O operations per second<ref>{{cite web|url=https://www.ibm.com/it-infrastructure/z/capabilities/connectivity|title=IBM Z - I/O Connectivity: FICON/zHPF/CTC|date=2012-11-15|website=www.ibm.com|language=en-US|access-date=2016-06-01}}</ref> and with a [[Mean time between failures|mean time between failure (MTBF)]]<ref>{{cite web|url=http://www.computerworld.com/article/2560019/computer-hardware/mtbf.html|title=MTBF|last=staff|first=Computerworld|website=Computerworld|date=31 October 2005|access-date=2016-06-01}}</ref> measured in decades.<ref name=":0">{{cite web|url=http://www.fool.com/investing/general/2015/01/24/heres-why-ibm-is-still-building-mainframes.aspx|title=Here's Why IBM Is Still Building Mainframes -- The Motley Fool|last=Green|first=Timothy|website=The Motley Fool|date=24 January 2015|access-date=2016-06-01}}</ref> Using virtualization, numerous smaller servers can be combined onto one mainframe, gaining some benefits of centralization and cost reduction, while still allowing specialized servers. Instead of [[paravirtualization]], IBM mainframes use [[full virtualization]], which permits workload density far greater than paravirtualization does.{{citation needed|reason=Provide source for definition of workload density and relationship to paravirtualization|date=October 2018}} Combining full virtualization of the hardware plus lightweight [[Z/VM|Virtual Machine]] containers that run Linux in isolation (somewhat similar in concept to [[Docker (software)|Docker]]) result in a platform that supports more virtual servers than any other in a single footprint,<ref>{{cite web|url=http://www.vm.ibm.com/overview/index.html|title=IBM: About the z/VM Operating System|date=2015-01-14|website=www.vm.ibm.com|language=EN|access-date=2016-06-01}}</ref> which also can lower operating costs. Additional savings can be seen from reduced need for floor space, power, cooling, networking hardware, and the other [[Data center infrastructure management|infrastructure]] needed to support a [[data center]]. IBM mainframes allow transparent use of [[Mainframe computer|redundant processor execution steps]] and [[Mainframe computer|integrity checking]], which is important for critical applications in certain industries such as banking.{{citation needed|reason=dubious|date=June 2013}} Mainframes typically allow [[Hot swapping|hot-swapping of hardware]], such as processors and memory. IBM Z provides fault tolerance for all key components, including processors, memory, I/O Interconnect, power supply, channel paths, network cards, and others. Through internal monitoring, possible problems are detected and problem components are designed to be switched over without even failing a single transaction.<ref>{{cite web|url=https://www.ibm.com/it-infrastructure/z/capabilities/resiliency|title=IBM Z - Business resiliency: Data Driven - Server|date=2010-10-26|website=www.ibm.com|language=en-US|access-date=2016-06-01}}</ref> In the rare event of failure, firmware will automatically enable a spare component, disable the failing component, and notify IBM to dispatch a service representative. This is transparent to the operating system, allowing routine repairs to be performed without shutting down the system. Many industries continue to rely on mainframes where they are considered to be the best option in terms of reliability, security, or cost.<ref name=":0" />
 
IBM mainframes allow transparent use of [[Mainframe computer|redundant processor execution steps]] and [[Mainframe computer|integrity checking]], which is important for critical applications in certain industries such as banking.{{citation needed|reason=dubious|date=June 2013}} Mainframes typically allow [[Hot swapping|hot-swapping of hardware]], such as processors and memory. IBM Z provides fault tolerance for all key components, including processors, memory, I/O Interconnect, power supply, channel paths, network cards, and others. Through internal monitoring, possible problems are detected and problem components are designed to be switched over without failing a transaction.<ref>{{cite web|url=https://www.ibm.com/it-infrastructure/z/capabilities/resiliency|title=IBM Z - Business resiliency: Data Driven - Server|date=2010-10-26|website=www.ibm.com|language=en-US|access-date=2016-06-01}}</ref> In the rare event of failure, firmware will automatically enable a spare component, disable the failing component, and notify IBM to dispatch a service representative. This is transparent to the operating system, allowing routine repairs to be performed without shutting down the system. Many industries continue to rely on mainframes where they are considered to be the best option in terms of reliability, security, or cost.<ref name=":0" />
==Pricing and costs==
Linux on IBM Z is not generally appropriate on-premises for small businesses that would have fewer than about 10 distributed Linux servers, although some expensive per-processor licensed software can quickly reduce that [[rule of thumb]]. Most software vendors, including IBM, treat the highly virtualized IFLs just like non-virtualized processors on other platforms for licensing purposes. In other words, a single IFL running scores of Linux instances still typically counts as one "ordinary" CPU, at the same CPU price, for software licensing. Test, development, quality assurance, training, and redundant production server instances can all run on one IFL (or more IFLs, but only if needed for peak demand performance capacity). Thus, beyond some minimum threshold, Linux on IBM Z can quickly become cost-advantageous when factoring in labor and software costs.
 
The cost equation for Linux on IBM Z is not always well understood and is controversial, and many businesses and governments have difficulty measuring, much less basing decisions on, software, labor, and other costs (such as the costs of outage and security breaches). Acquisition costs are often more visible, and small, non-scalable servers are "cheap." Nonetheless, non-acquisition costs are no less real and are usually far greater than hardware acquisition prices.{{citation needed|reason=dubious|date=June 2013}} Also, individual users and departments within larger businesses and governments sometimes have difficulty sharing computing infrastructure (or any other resources, for that matter), citing a loss of control. Server centralization, as Linux on IBM Z provides, might reward cooperation with better service and lower costs, but that's not to say that cooperation is always easily accomplished within a corporate bureaucracy.
 
Linux on IBM Z also supports less expensive disk storage devices than z/OS because Linux does not require FICON or ESCON attachment, although z/OS may use disk space more efficiently, on balance, due to hardware-assisted database compression common on z/OS and the smaller number of operating system instances z/OS typically requires. There are also some operational advantages using some FICON-attached storage with Linux on IBM Z, for example support for z/VM Live Guest Relocation.
 
==Appropriate workloads==
Mainframe characteristics are designed for such business workloads as transaction processing (especially in conjunction with concurrent, high volume batch processing) and large database management. Mainframe design traditionally emphasizes "balanced" performance for all computing elements including input/output, implemented via [[channel I/O]]. Mainframes offload I/O, system accounting, and other non-core computing tasks from the main CPUs as much as possible, and z/Architecture additionally offloads cryptographic calculations. For example, in a single IBM z13 machine up to 141 processor cores are available to configure as IFLs. However, every such machine also has 27 additional main cores: 2 as spares, 1 for firmware support, and the remainder running system accounting and I/O support tasks. In addition, each I/O adapter typically has two [[PowerPC]] processors, and a z13 supports hundreds of I/O adapters. There are also separate processors handling memory and cache control tasks, environmental monitoring, and internal interconnections, as examples.
 
Historically, mainframes in general, and Linux on IBM Z in particular, did not execute "CPU-intensive" single task computations with notably high performance compared to certain other platforms with a few notable exceptions such as cryptographic calculations. Examples included most scientific simulations, [[weather forecasting]], and [[computational chemistry|molecular modeling]]. [[Supercomputer]]s, including Linux-based supercomputers, excel at these workloads. This bifurcation between mainframes and other platforms has significantly blurred in recent years, starting with the introduction of 2008's System z10, a machine based on quad-core 4.4&nbsp;GHz processors with [[IBM System z10#Decimal floating point|hardware decimal floating point]]. As mainframe processor technology has continued to evolve, and especially with the introduction of the IBM LinuxONE and IBM z13 models in 2015, IBM has started promoting its mainframes as ideal platforms to run real-time analytics and other computationally intensive tasks that mainframes did not historically run well.
 
Mainframes do not provide graphics or sound adapters, and are as such ill-suited for [[digital media]] editing or [[computer-aided design]] (CAD) except perhaps in support roles (e.g. content storage, parts inventories, metadata management, security services, etc.)
 
==Support==
Like all other versions of Linux, Linux on IBM Z is governed by the GPL [[free software]] license. Complete Linux on IBM Z [[source code]] is available from numerous parties on a free and equal basis, and architectural support is part of the main Linux kernel effort. IBM assigns several of its programmers to the community effort, but IBM is by no means the only participant.
 
Though there are no obstacles to running any Linux on IBM Z distribution on an IBM z System, IBM routinely tests three particular Linux on IBM Z distributions: [[Red Hat Enterprise Linux|Red Hat]],<ref>{{cite web|title=Linux on IBM Z/IBM LinuxONE tested platforms|date=7 June 2024 |url=https://www.ibm.com/support/pages/node/6191619|publisher=IBM|access-date=223 NovJuly 20212024}}</ref> [[SUSE Linux Enterprise Server|SUSE]],<ref>{{cite web|title=IBM Z: Linux on IBM Z - Resources - Tested platforms|url=https://www.ibm.com/it-infrastructure/z/os/linux-tested-platforms|publisher=IBM|access-date=5 June 2013}}</ref> and starting in 2015, [[Canonical (company)|Canonical]]'s [[Ubuntu|Ubuntu Linux]].<ref>{{cite web|title=Linux on IBM Z tested platforms|url=https://www.ibm.com/support/pages/node/6191619|publisher=IBM|access-date=2 Nov 2021}}</ref> Other notable Linux on IBM Z distributions include [[Debian]] (upstream for Ubuntu),<ref>{{cite web|title=S/390 Port|url=http://www.debian.org/ports/s390/|publisher=Debian|access-date=5 June 2013}}</ref> [[Fedora Linux|Fedora]] (upstream for RHEL),<ref>{{cite web|title=Architectures/s390x|url=http://fedoraproject.org/wiki/Architectures/s390x|publisher=Fedora Project|access-date=5 June 2013}}</ref> [[Slackware]],<ref>{{cite web|title=The Slack/390 Linux Project|url=http://www.slack390.org/|publisher=Slackware Inc.|access-date=25 November 2018|archive-url=https://web.archive.org/web/20190223154310/http://www.slack390.org/|archive-date=23 February 2019|url-status=dead}}</ref> [[CentOS]], [[Alpine Linux]]<ref>{{Cite web|title=downloads {{!}} Alpine Linux|url=https://alpinelinux.org/downloads/|access-date=2021-06-20|website=alpinelinux.org}}</ref> and [[Gentoo Linux|Gentoo]].<ref>{{cite web|title=Project:S390|url=https://wiki.gentoo.org/wiki/Project:S390|publisher=Gentoo|access-date=16 October 2014}}</ref>
 
Nearly every free or open-source software package available for Linux generally is available for Linux on IBM Z, including [[Apache HTTP Server]], [[Samba (software)|Samba]], [[JBoss]], [[PostgreSQL]], [[MySQL]], [[PHP]], [[Python (programming language)|Python programming language]], [[Concurrent Versions System]] (CVS), [[GNU Compiler Collection]] (GCC), [[LLVM]], and [[Perl]], and [[Rust (programming language)|Rust]],<ref>{{Cite web|url=https://github.com/rust-lang/rust/pull/36369|title = Add s390x support by uweigand · Pull Request #36369 · rust-lang/Rust|website = [[GitHub]]}}</ref> among many others.<ref>{{cite web|title=Debian autobuilder status for s390, 29 April 2013|url=https://buildd.debian.org/stats/s390.txt|archive-url=https://archive.today/20130624195211/https://buildd.debian.org/stats/s390.txt|url-status=dead|archive-date=24 June 2013|publisher=Debian|access-date=5 June 2013}}</ref>
 
Red Hat and SUSE offer mainline support for their distributions running Linux on IBM Z.<ref>{{cite web|title=Red Hat Enterprise Linux for IBM Z|url=http://www.redhat.com/products/enterprise-linux/for-ibm-system-z/|publisher=Red Hat|access-date=5 June 2013}}</ref><ref>{{cite web|title=SUSE Linux Enterprise Server for Z|url=https://www.suse.com/products/systemz/|publisher=SUSE|access-date=5 June 2013}}</ref> In 2015 Canonical announced plans to offer official support for its distribution starting in early 2016. [[IBM Global Services]] also offers support contracts, including 24x7 coverage.<ref>{{cite web|title=IBM Services and Support for Linux|url=http://www-03.ibm.com/linux/services.html|publisher=IBM|access-date=5 June 2013|archive-url=https://web.archive.org/web/20131213233247/http://www-03.ibm.com/linux/services.html|archive-date=2013-12-13|url-status=dead}}</ref> Some standard Linux software applications are readily available pre-compiled, including popular closed-source enterprise software packages such as [[IBM WebSphere|WebSphere]],<ref>{{cite web|title=WebSphere MQ for Linux for System z |url=http://www-01.ibm.com/software/integration/wmq/linux_systemZ/ |publisher=IBM |access-date=5 June 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130102035347/http://www-01.ibm.com/software/integration/wmq/linux_systemZ/ |archive-date= 2 January 2013}}</ref> [[IBM Db2]]<ref>{{cite web|title=Installation requirements for DB2 servers and IBM data server clients (Linux)|url=httphttps://pic.dhewww.ibm.com/infocenterdocs/db2luwen/v10r1dscp/index10.1.jsp0?topic=%2Fcom.ibm.db2.luw.qb.server.doc%2Fdoc%2Fr0008865.htmlinstallation-linux|work=Installing IBM DB2Data VersionServer 10.1drivers Informationand clients| date=13 March 2014 Center|publisher=IBM|access-date=523 JuneJuly 20132024}}</ref> and [[Oracle database|Oracle]]<ref>{{cite web|title=IBM System z: Linux on System z - Solutions - zSolution Oracle - Overview|url=https://www.ibm.com/it-infrastructure/z/os/linux|publisher=IBM|access-date=5 June 2013}}</ref> databases and applications, [[SAP R/3]], [[SAP ERP]],<ref>{{cite web|title=SAP Applications Empower Business|url=http://public.dhe.ibm.com/common/ssi/ecm/en/zss03019usen/ZSS03019USEN.PDF|access-date=5 June 2013}}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes}}</ref> and IBM's [[Java (programming language)|Java]] Developer's Kit (JDK),<ref>{{cite web|title=developerWorks : Technical Topics : Java technology : IBM Developer kits : Linux : Download information|website=[[IBM]] |url=http://www.ibm.com/developerworks/java/jdk/linux/download.html|access-date=5 June 2013|archive-url=https://web.archive.org/web/20130728144501/http://www.ibm.com/developerworks/java/jdk/linux/download.html|archive-date=28 July 2013|url-status=dead}}</ref> to name only a few.
 
==Developer resources==
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* The Linux Remote Development Program, a fee-based extended developer support program.<ref>{{cite web|title=Linux Remote Development Program|url=https://www.ibm.com/partnerworld/wps/servlet/ContentHandler/stg_com_sys_linux_rdp|publisher=IBM|access-date=5 June 2013}}</ref>
 
Linux on IBM Z supports [[Unicode]] and [[ASCII]] just like any other Linux distribution&mdash;it is not an [[EBCDIC]]-based operating system.<ref>{{cite web|title=Mainframe operating system: Linux for System z|url=httphttps://publib.boulderwww.ibm.com/infocenterdocs/en/zos/basics/index.jsp-basic-skills?topic=/com.ibm.zos.zmainframe/zconc_opsyslinuxintro.htmsystems-mainframe-operating-system-linux-system-z|work=z/OS basic skills informationMainframe centerconcepts|publisher=IBM|access-date=523 JuneJuly 20132024}}</ref> However, for convenience Linux is able to read kernel parameters in EBCDIC. z/VM takes advantage of this capability.
 
Porting Linux applications to Linux on IBM Z is fairly straightforward. Potential issues include [[endianness]] (Linux on IBM Z is big-endian) and reliance on non-portable libraries particularly if source code is not available.<ref>{{cite web|last=Gellerich|first=Wolfgang|title=Porting applications to Linux for Z|url=http://www.ibm.com/developerworks/library/l-systemz/|work=IBM developerWorks|publisher=IBM|access-date=23 October 2013}}</ref> Programs can be easily [[cross compiler|cross compiled]] to z/Architecture binaries on non-mainframe Linux systems.<ref>{{cite web|title=How to|url=http://www.ibm.com/developerworks/linux/linux390/howto.html#how_to_3|work=IBM developerWorks|access-date=23 October 2013}}</ref>
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==External links==
* [https://www.ibm.com/it-infrastructure/z/os/linux Linux on IBM Z]
* [https://www.ibm.com/it-infrastructure/linuxone IBM LinuxONE servers]
* [http://www.openmainframeproject.org/ Open Mainframe Project]
* [http://www.vm.ibm.com/linux/ Linux on z/VM]
* [httphttps://wwwdeveloper.ibm.com/developerworkstechnologies/linux/linux390/ Linux on IBM Z] developer site
* [http://linuxvm.org/ Linux for S/390 and zSeries] web site
* [http://wiki.linuxvm.org/ Linux for S/390 and zSeries] {{Webarchive|url=https://web.archive.org/web/20160304071339/http://wiki.linuxvm.org/ |date=2016-03-04 }} community wiki
* [http://www2.marist.edu/htbin/wlvindex?LINUX-390 linux-390], users mailing list
* [http://vger.kernel.org/vger-lists.html#linux-s390 linux-s390], kernel devel mailing list
Retrieved from "https://en.wikipedia.org/wiki/Linux_on_IBM_Z"