Apple–Intel architecture

This article is about the architecture of Intel-based Apple computers. For information about the transition to this architecture, see Apple's transition to Intel processors.

The Apple–Intel architecture, or Mactel, is an unofficial name used for Apple Macintosh personal computers developed and manufactured by Apple Inc. that use Intel x86 processors, rather than the PowerPC and Motorola 68000 ("68k") series processors used in their predecessors. With the change in architecture, a change in firmware became necessary; Apple selected the Intel-designed Extensible Firmware Interface (EFI) as its comparable component to the Open Firmware used on its PowerPC architectures, and as the firmware-based replacement for the PC BIOS from Intel. With the change in processor to the Intel x86 and its support of Intel VT-x, users were given access to high performance, near-native virtualization, allowing them to run and switch between two or more operating systems simultaneously.

Background

Apple–Intel architecture (Mactel) is an unofficial name used for Apple Macintosh personal computers developed and manufactured by Apple Inc. that use Intel x86 processors. As the name implies, it refers to chances in the architecture over the earlier PowerPC, Apple 68k, and other preceding processors.

Technologies

Background

Apple uses a subset of the standard PC architecture, which provides support for Mac OS X and support for other operating systems. Hardware and firmware components that must be supported to run an operating system on Apple-Intel hardware include the Extensible Firmware Interface.

The EFI and GUID Partition Table

Main article: Extensible Firmware Interface

Main article: GUID Partition Table

With the change in architecture, a change in firmware became necessary. Extensible Firmware Interface (EFI) is the firmware-based replacement for the PC BIOS from Intel. Designed by Intel, it was chosen by Apple to replace Open Firmware, used on PowerPC architectures. Since many operating systems, such as Windows XP and many versions of Windows Vista, are incompatible with EFI, Apple has released a firmware upgrade with a compatibility support module that provides a subset of traditional BIOS support with their Boot Camp product.

GUID Partition Table (GPT) is a standard for the layout of the partition table on a physical hard disk. It is a part of the Extensible Firmware Interface (EFI) standard proposed by Intel as a substitute for the more common PC BIOS. The GPT replaces the Master Boot Record (MBR) used with BIOS.

Booting

To Mac operating systems

Intel Macs can boot in two ways: directly via EFI, or in a "legacy" BIOS compatibility mode. For multibooting, holding down "Option" gives a choice of bootable devices, while the rEFInd bootloader is commonly used for added configurability.

Standard Live USBs cannot be used on IntelMacs; the EFI firmware can recognize and boot from USB drives, but it can only do this in EFI mode–when the firmware switches to BIOS mode, it no longer recognizes USB drives, due to lack of a BIOS-mode USB driver. Many operating systems, such as Windows and Linux, can only be booted in BIOS mode, or are more easily booted or perform better when booted in BIOS mode, and thus USB booting on IntelMacs is largely limited to Mac OS X, which can easily be booted via EFI. This limitation could be fixed by either patching the Apple firmware to include a USB driver in BIOS mode, or the operating systems to remove the dependency on the BIOS.

To non-Mac operating systems

Main article: Boot Camp (software)

File:Mac mini Intel Core.jpg

Mac Mini with Intel Core

On April 5, 2006, Apple made available for download a public beta version of Boot Camp, a collection of technologies which allows users of Intel-based Macs to boot Windows XP Service Pack 2. On March 28, 2007, Boot Camp 1.2 Beta was released which supports Windows Vista. The final version of Boot Camp is included in Mac OS X v10.5, "Leopard." Prior to Boot Camp, which provides most hardware drivers for Windows XP, drivers for XP were difficult to find.

Linux can also be booted with Boot Camp.

Digital Rights Management

Digital Rights Management in the Apple-Intel architecture is accomplished via the Dont Steal Mac OS X.kext, sometimes referred to as DSMOS or DSMOSX, a file present in Intel-capable versions of the Mac OS X operating system. Its presence enforces a form of Digital Rights Management, preventing Mac OS X being installed on stock PCs. The name of the kext is a reference to the Mac OS X license conditions, which allow installation on one piece of Apple hardware only. According to Apple, anything else is stealing Mac OS X. The kext is located at /System/Library/Extensions on the volume containing the operating system. The extension contains a kernel function called page_transform() which performs AES decryption of "apple-protected" programs. A Mac OS X system which is missing this extension, or a system where the extension has determined it's not running on Apple hardware, will be missing this decryption capability, and as a result will not be able to run the Apple-restricted binaries Dock, Finder, loginwindow, SystemUIServer, mds, ATSServer, backupd, fontd, translate, or translated.

Virtualization

The Intel Core Duo, Core 2 Duo, Core i5, Core i7, and Xeon processors found in Intel Macs support Intel VT-x, which allows for high performance (near native) virtualization, which gives the user the ability to run and switch between two or more operating systems simultaneously, rather than having to dual-boot and run only one operating system at a time.

The first software to take advantage of this technology was Parallels Desktop for Mac, which was released in June 2006. The Parallels virtualization products allow users to use installations of Windows XP, Windows Vista, or Windows 7 in a virtualized mode while running OS X. VirtualBox is virtualization software from Oracle Corporation, which was released January 2007. Available for Mac OS X as well as other host operating systems, it supports Intel VT-x and can run multiple other guest operating systems, including Windows XP, Vista, and 7; it is available free of charge under either a proprietary license or the GPL free software license. VMware offers a product similar to Parallels called Fusion, which was released August 2007. VMware's virtualization product also allows users to use installations of Windows XP, Vista, or 7 in a virtualized mode while running OS X.

There are, however, many subtle differences between these products; Regardless of the product used, there are always limitations and inconveniences in using a virtualized guest OS versus the native Mac OS or an alternative OS solution offered by Boot Camp.

See also

• Apple's transition to Intel processors

External links

• Intel EFI Open-source implementation, code-name 'Tiano'

• Note, Linux and X.org rely on BIOS mode to initialize the video hardware, and hence under EFI-booting, Linux and X do not have hardware accelerated video.
• Anon. (2012). "Linux netticasinon asentaminen MacBook Pro tietokoneeseen" [Finnish language organizational blog entry], Mactel (May 29), see [1], accessed 11 October 2015.