1132718Skan@c Copyright (C) 2001, 2002, 2004 Free Software Foundation, Inc. 290075Sobrien@c This is part of the GCC manual. 390075Sobrien@c For copying conditions, see the file gcc.texi. 490075Sobrien 590075Sobrien@node Configure Terms 690075Sobrien@section Configure Terms and History 790075Sobrien@cindex configure terms 890075Sobrien@cindex canadian 990075Sobrien 1090075SobrienThe configure and build process has a long and colorful history, and can 1190075Sobrienbe confusing to anyone who doesn't know why things are the way they are. 1290075SobrienWhile there are other documents which describe the configuration process 1390075Sobrienin detail, here are a few things that everyone working on GCC should 1490075Sobrienknow. 1590075Sobrien 1690075SobrienThere are three system names that the build knows about: the machine you 1790075Sobrienare building on (@dfn{build}), the machine that you are building for 1890075Sobrien(@dfn{host}), and the machine that GCC will produce code for 1990075Sobrien(@dfn{target}). When you configure GCC, you specify these with 2090075Sobrien@option{--build=}, @option{--host=}, and @option{--target=}. 2190075Sobrien 2290075SobrienSpecifying the host without specifying the build should be avoided, as 2390075Sobrien@command{configure} may (and once did) assume that the host you specify 2490075Sobrienis also the build, which may not be true. 2590075Sobrien 2690075SobrienIf build, host, and target are all the same, this is called a 2790075Sobrien@dfn{native}. If build and host are the same but target is different, 2890075Sobrienthis is called a @dfn{cross}. If build, host, and target are all 2990075Sobriendifferent this is called a @dfn{canadian} (for obscure reasons dealing 3090075Sobrienwith Canada's political party and the background of the person working 3190075Sobrienon the build at that time). If host and target are the same, but build 3290075Sobrienis different, you are using a cross-compiler to build a native for a 3390075Sobriendifferent system. Some people call this a @dfn{host-x-host}, 3490075Sobrien@dfn{crossed native}, or @dfn{cross-built native}. If build and target 3590075Sobrienare the same, but host is different, you are using a cross compiler to 3690075Sobrienbuild a cross compiler that produces code for the machine you're 37132718Skanbuilding on. This is rare, so there is no common way of describing it. 38132718SkanThere is a proposal to call this a @dfn{crossback}. 3990075Sobrien 4090075SobrienIf build and host are the same, the GCC you are building will also be 4190075Sobrienused to build the target libraries (like @code{libstdc++}). If build and host 4290075Sobrienare different, you must have already build and installed a cross 4390075Sobriencompiler that will be used to build the target libraries (if you 4490075Sobrienconfigured with @option{--target=foo-bar}, this compiler will be called 4590075Sobrien@command{foo-bar-gcc}). 4690075Sobrien 4790075SobrienIn the case of target libraries, the machine you're building for is the 4890075Sobrienmachine you specified with @option{--target}. So, build is the machine 4990075Sobrienyou're building on (no change there), host is the machine you're 5090075Sobrienbuilding for (the target libraries are built for the target, so host is 5190075Sobrienthe target you specified), and target doesn't apply (because you're not 5290075Sobrienbuilding a compiler, you're building libraries). The configure/make 5390075Sobrienprocess will adjust these variables as needed. It also sets 5490075Sobrien@code{$with_cross_host} to the original @option{--host} value in case you 5590075Sobrienneed it. 5690075Sobrien 5790075SobrienThe @code{libiberty} support library is built up to three times: once 5890075Sobrienfor the host, once for the target (even if they are the same), and once 5990075Sobrienfor the build if build and host are different. This allows it to be 6090075Sobrienused by all programs which are generated in the course of the build 6190075Sobrienprocess. 62