FreeBSD Platforms

The FreeBSD Unix operating system supports a number of processor architectures, or platforms. The FreeBSD development team classifies the level of support as a tier, with Tier-1 being most compatible and supported on a certain architecture and Tier-2 (and beyond) being varying degrees of compatibility and support.

The most obvious, and some might say ubiquitous, of the processor architectures is the i386 from Intel and the various clones from AMD, IBM / Cyrix and others. This architecture is widely used in all computers commonly referred to as 'PCs' and as such many of the World's operating systems support it, particularly Microsoft's range of Windows operating systems.

The following is a list of FreeBSD supported processor architectures:

i386

This is the architecture that will work on almost all Intel and AMD processors, both 32bit and 64bit though it will only use the 32bit mode of these processors. The i386 pre-dates the ubiquitous Pentium range of processors by two generations with the i486 processor existing between them. Therefore the backwards compatibility of the newer Intel and AMD processors ensures this architecture remains available.

i486

This is simply the next generation of processor architecture from Intel, with other manufacturers making compatible clones of it. FreeBSD does not have a specific i486 release to run on this processor instead the i386 version is used for this specific architecture using the in-built backwards compatibility.

Pentium (i586)

The Pentium was simply a branding of next generation processors from Intel which moved away from the numerical naming of processors up until that point. The original processor in this generation is technically the i586 architecture with later Pentium processors, namely the Pentium II and Pentium III et al, being the i686 architecture.

FreeBSD has no specific Pentium (either i586 or i686) release to run on this processor instead the i386 version is used for this specific architecture using the in-built backwards compatibility.

Intel x86-64

This is another generation of processor architecture from Intel that featured 64bit processing. Intel moved away from the Pentium brand with this generation instead using the brand names Intel Core2 Duo amongst others.

FreeBSD uses the AMD64 name for the specific release for this architecture (refer to the AMD64 section).

Note: this processor architecture is different from the ia64 architecture used in the Itanium and Itanium 2 branded Intel processors (refer to the ia64 section).

Itanium / Itanium 2 (ia64)

The Itanium and the second generation Itanium 2 architecture was a radical change from the original Intel i386 generation of processors which saw a brand-new redesign of the processor core. As such they have no backwards-compatibility with any of the Intel i386 later generation of processor architecture.

FreeBSD has a specific release for this architecture but is limited by specific supported systems. As such this is a Tier-2 platform.

PC98

The PC98 was not specifically a processor but rather a standard for describing the hardware of a 'PC98' branded system. These PC98 branded systems were technically i386-compatible in architecture and were made by the large Japanese manufacturers such as EPSON and NEC. Therefore PC98 systems were typically found in Japan and neighbouring areas.

All but newer PC98 systems (which feature New Extended Standard Architecture, or NESA) are support by the i386 release of FreeBSD.

Sparc64

The Sparc64 architecture is a processor originally designed by Sun Microsystems but recently released under an open license. This is an entirely different architecture from the Intel and compatible processors and uses RISC as the underlying functionality. It is largely found in Sun's own line of servers.

FreeBSD has a specific release for this architecture but is limited in functionality depending on the Sun server it is running on.

Note: Sun Microsystems are themselves a UNIX operating system vendor with their Solaris product range.

AMD64

The AMD64 is the brand name for the 64bit generation of processor architecture from AMD. The underlying functionality is different to that of Intel's 64bit implementation (on their x86-64 processors) although the two technologies are typically grouped under the title 'x64' by software vendors to denote neutrality between the two processor manufacturers. As such the majority of 64bit-enabled operating systems will run on either architecture without requiring two separate releases.

FreeBSD has a specific release for this architecture under the AMD64 title (refer to the x86-64 section).

PowerPC

The PowerPC is the brand name for the processor architecture designed by collaboration between Apple, IBM and Motorola. This architecture was commonly used in Apple systems prior to their migration to the Intel architecture (that of the later generation Pentium brand) however it remains in use by IBM in their server range.

FreeBSD is in an initial stage of developing support for this platform and as such there is little information on the availability of a specific release for this architecture.

Architecture specific FreeBSD

While the above list of architectures are available as releases from the FreeBSD project website it is possible to make a version of FreeBSD for a specific processor.

As an example, a system administrator could install FreeBSD on a latest-generation Pentium processor - say a Core2 Duo - using the i386 release of the FreeBSD CD-ROMs. This would, as mentioned in the relevant subsections above, only utilise the i386 compatibility of the Pentium processor. The system administrator could then recompile the FreeBSD kernel using the original source code and configuring the compiler to use Pentium-specific architecture. This will take advantage of the processors cutting-edge features and is typically done to improve the performance of the operating system as a whole. Software from the ports system can be compiled in much the same way.