Editing Cross compiler (section)

== Use ==
The fundamental use of a cross compiler is to separate the build environment from target environment.  This is useful in several situations:
* [[embedded system|Embedded computers]] where a device has highly limited resources. For example, a microwave oven will have an extremely small computer to read its keypad and door sensor, provide output to a digital display and speaker, and to control the microwave for cooking food. This computer is generally not powerful enough to run a compiler, a file system, or a development environment.
* Compiling for multiple machines.  For example, a company may wish to support several different versions of an operating system or to support several different operating systems.  By using a cross compiler, a single build environment can be set up to compile for each of these targets.
* Compiling on a [[server farm]]. Similar to compiling for multiple machines, a complicated build that involves many compile operations can be executed across any machine that is free, regardless of its underlying hardware or the operating system version that it is running.
* [[Bootstrapping (compilers)|Bootstrapping]] to a new platform. When developing software for a new platform, or the emulator of a future platform, one uses a cross compiler to compile necessary tools such as the operating system and a native compiler.
* Compiling native code for [[emulator]]s for older now-obsolete platforms like the Commodore 64 or Apple II by enthusiasts who use cross compilers that run on a current platform (such as Aztec C's MS-DOS [[MOS Technology 6502|6502]] cross compilers running under [[Windows XP]]).

Use of [[virtual machine]]s (such as Java's [[Java virtual machine|JVM]]) resolves some of the reasons for which cross compilers were developed. The virtual machine paradigm allows the same compiler output to be used across multiple target systems, although this is not always ideal because virtual machines are often slower and the compiled program can only be run on computers with that virtual machine.

Typically the [[hardware architecture]] differs (e.g. coding a program destined for the [[MIPS architecture]] on an [[x86]] computer) but cross-compilation is also usable when only the [[operating system]] environment differs, as when compiling a [[FreeBSD]] program under [[Linux]], or even just the system library, as when compiling programs with [[uClibc]] on a [[glibc]] host.