26.1 Host and Target

We will first discuss using GNU Autotools to build cross compilation tools. For example, the information in this section will explain how to configure and build the GNU cc compiler as a cross compiler.

When building cross compilation tools, there are two different systems involved: the system on which the tools will run, and the system for which the tools will generate code. The system on which the tools will run is called the host system. The system for which the tools generate code is called the target system.

For example, suppose you have a compiler which runs on a GNU/Linux system and generates ELF programs for a MIPS-based embedded system. In this case, the GNU/Linux system is the host, and the MIPS ELF system is the target. Such a compiler could be called a GNU/Linux cross MIPS ELF compiler, or, equivalently, a `i386-linux-gnu' cross `mips-elf' compiler. We discussed the latter sorts of names earlier; see 3.4 Configuration Names.

Naturally, most programs are not cross compilation tools. For those programs, it does not make sense to speak of a target. It only makes sense to speak of a target for programs like the GNU compiler or the GNU binutils which actually produce running code. For example, it does not make sense to speak of the target of a program like make.

Most cross compilation tools can also serve as native tools. For a native compilation tool, it is still meaningful to speak of a target. For a native tool, the target is the same as the host. For example, for a GNU/Linux native compiler, the host is GNU/Linux, and the target is also GNU/Linux.