OSx86 (a portmanteau of OS X and x86) is a collaborative hacking project to run the Mac OS X computer operating system on non-Apple personal computers with x86 architecture processors. The effort started soon after the June 2005 Worldwide Developers Conference announcement that Apple would be transferring their personal computers from PowerPC to Intel microprocessors. Such operation is not permitted by the software license that Mac OS X is distributed under.

A computer built to run this type of Mac OS X is sometimes known as a Hackintosh, which is a recycled term originally denoting the modified Lisa 2/10 running Mac System, or Macintosh.

Developer Transition Kit

Initial efforts to run Mac OS X on non-Apple hardware revolved around leaked copies of the Development DVD released by Apple. This Developer Transition Kit was made available to registered developers at a cost of $999. Being beta software, many updates followed its release. The first patches centered around circumventing the Trusted Platform Module (TPM) that was included on the motherboard of the Developer Transition Kits. The TPM was required by the Rosetta technology that allowed software compiled for the PowerPC architecture to run on Intel-based architecture. Removing this requirement allowed Mac OS X to be installed on non-Apple computers. Rosetta also required microprocessors that included SSE3 instructions. Patches were released to the community which emulated these instructions with SSE2 equivalents and allowed the installation on machines without SSE3 support, although this produced a performance penalty.

In October 2005 Apple released a 10.4.3 update to developers that required NX bit microprocessor support. Patches were released to circumvent this.

Mac OS X on Intel

On January 10 2006, Apple released Mac OS X 10.4.4 with the first generation of Intel-based Macs, the iMac and the MacBook Pro. These machines used Extensible Firmware Interface (EFI) platform firmware instead of the legacy BIOS found on most x86 motherboards. On February 14, 2006 an initial "crack" of Mac OS X v10.4.4 was released on the Internet by a hacker using the pseudonym Maxxuss. Within hours Apple released the 10.4.5 update, which was patched again by Maxxuss in less than two weeks. On April 3 2006 Apple released their 10.4.6 update and again patches were released within two weeks that allowed users to install most of this update on non-Apple computers, although this did not include the updated kernel in 10.4.6. These patches were released by SemjaZa and compiled by JaS. In June, JaS released the 10.4.7 Mac OS X update for non-Apple computers using the 10.4.4 kernel.

Up to the release of the 10.4.8 update, all OSx86 patches used the 10.4.4 kernel with the rest of the operating system at version 10.4.8. However, the newer frameworks relied on the newer kernels and this led to users of 10.4.8 encountering many problems. Apple also started making more use of SSE3 instructions on their hardware making it even more difficult for users with CPUs supporting only SSE2 to get a fully compatible system running.

A eletronics company called Psystar is using OSx86 developments to offer computers with Mac OS preinstalled

XNU kernel patch

Two programmers, working under the pseudonyms Mifki or Vitaliy and Semthex released new kernels by starting with the open source XNU tree and applying patches necessary to run the kernel on non-apple hardware. Mifki's goal was to release the kernel with as few patches as possible, able to run on close-to-Apple hardware. Semthex's goal was to make his kernel more compatible with legacy hardware with the omission of some crucial features.

Both kernels allowed most of the updated kernel extensions/frameworks to work, making properly configured beige-box PCs operate more like genuine Apple computers. While Mifki has only updated his kernel once, Semthex updates it regularly and added AMD, VMware and SSE2-support in later versions. Semthex released his hacked kernel source code on his webpage. On December 24, 2006 he also released the latest patches for the SSE3 kernel as a diff file for his original source tree as a Christmas present to the community. Special attention should be given to the SSE2 emulation which Semthex developed together with Rufus. This emulation was the first fully complete emulation of all SSE3 instructions to be presented to the OSx86 community. The previous SSE2 emulation was incomplete, only emulating 3 of the available SSE3 instructions, and very inefficient compared to the new emulator. The new emulator enabled even SSE2 OSx86 users to run SSE3 based applications such as iTunes 7 and most 3D programs.

In the early days of 10.4.8, an Intel-SSE3 only install DVD was released by JaS, which included Vitaliy's and Semthex's kernel. A few weeks later, a hacker calling themselves tubgirl released an AMD-SSE3 install DVD. With Semthex's successful completion of the SSE2 Kernel, JaS released an SSE2-SSE3 universal DVD and announced his retirement from hacking Mac OS X after seven successful DVD releases. However, on August 9, 2008, JaS released yet another distribution featuring both a client and server version of Mac OS 10.5.4.

In March 2007 the OSx86 community made some significant progress with the development of a Live DVD. The Live DVD allows booting to a working system with Mac OS X v10.4.8. Several movies appeared on the web demonstrating this.

A popular resource for users trying to setup their own Hackintosh machines was at At the end of March 2007, the InsanelyMac website was sold to a UK based company called Fubra Limited. Some people objected to the "commercialization" of the website, including kernel hacker Semthex and other developers, which was followed by a major split of the community.

Mac OS X v10.5

The following Leopard 10.5 builds: 9A466, 9A499, 9A527, 9A559 (all pre-release developer builds, the earliest from the WWDC); 9A581 (the 10.5.0 release build), 9B13 (developer), and 9B18 (10.5.1 release build) were successfully installed onto conventional PC hardware. The only known prepatched DVDs, such as JaS or Goatsecx, are the Kalyway (developer build 9a527 from August 2007) and ToH RC2 (build 9A581) DVDs. These patches were created by a hacker with the alias "The Mad Hatter," but the kernels were made by Lorem (build 9A466), SynthetiX (builds 9A499, 9A527 and 9A559), ToH (builds 9A581, 9B13 and 9B18) and more recently a group calling them selves StageXNU(Darwin 9.4.0). Their contributions trickled down into various Mac OSx86 installers, readily available on the internet.

BrazilMac created one of the first patching processes which made it convenient for users to install Mac OS X onto 3rd party hardware by using a legally obtained, retail version of Apple Mac OS X. It was utilizing the BrazilMac patch that many effortless distros of Mac OSx86 came to fruition.

A hacker by the alias of "Uphuck" working with a team called "osx86.turk" created series of DVD images "Codename: iATKOS", which include a full install of Mac OS X Leopard. Distributed over the internet, these installers violate the terms of Apple's license agreement. A team of hackers called "Kalyway" created another standalone 10.5.1 installer DVD image (or iso), also distributed via peer to peer filesharing systems, such as LimeWire and BitTorrent, also against Apple's terms. A hacker called "Zephyroth" released 10.5.2 for the AMD based PC's. There continue to be refined and updated builds released.

The OSx86 community has been quick to make the necessary modifications to enable Apple's latest releases to run on non-Apple hardware. Within hours of Leopard's release, an AMD/Intel SSE2/3 Kernel Patcher was created to remove the HPET requirement from an original untouched mach_kernel file, a core component of the Mac OS.

EFI emulation

Extensible Firmware Interface (EFI) is a specification that defines a software interface between an operating system and platform firmware.

In early November 2007, a group of hackers (fronted by a Russian hacker known as Netkas), using an already modified boot-132 source root from David Elliot (also known as dfe), developed a method of emulating an EFI environment using a specially modified Darwin bootloader. In practical terms, this meant that regular PCs meeting a minimum set of hardware requirements could now be "seen" as real Macintosh computers by the OS, allowing the use of unmodified, "stock" Apple kernels and thus giving a more transparent and reliable operation. Several methods for real world deployment of this innovative solution have arisen all around the net. An explanation of this achievement along with a usage guide was provided by the website

True EFI emulation was a highly sought after asset for the OSx86 community. Previous efforts based upon Apple’s open source Darwin Project and Hackintosh gurus allowed users to enjoy OS X on normal PCs, with patched kernels/kernel modules which simply bypassed EFI. Using the EFI patch, a Hackintosh could boot off "vanilla" (unmodified) OS X kernels and use vanilla kernel extensions. This not only allowed the system to be compatible with future system updates, but also offered increased stability. This method also circumvents Apple's End User License Agreement, which states that the modification of non-Open-Source components of the OS is forbidden.

Recently a new commercial product, EFi-X, was released that claims to allow full, simple booting off official Leopard install disks, and a subsequent install, without any patching required.


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