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<HTML><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><!-- Created on September, 12 2004 by texi2html 1.64 --><!-- Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author) Karl Berry <karl@freefriends.org> Olaf Bachmann <obachman@mathematik.uni-kl.de> and many others.Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>Send bugs and suggestions to <texi2html@mathematik.uni-kl.de> --><HEAD><TITLE>Autoconf, Automake, and Libtool: Supporting Cross Compiler in Make</TITLE><META NAME="description" CONTENT="Autoconf, Automake, and Libtool: Supporting Cross Compiler in Make"><META NAME="keywords" CONTENT="Autoconf, Automake, and Libtool: Supporting Cross Compiler in Make"><META NAME="resource-type" CONTENT="document"><META NAME="distribution" CONTENT="global"><META NAME="Generator" CONTENT="texi2html 1.64"><script language="Javascript"><!-- // Check the browser version. function checkVersion() { if (navigator.appVersion.charAt(0)>=3) return true; if (navigator.appVersion.charAt(0)>=4) return true; 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If you compile this subsidiary programusing <SAMP>`$(CC)'</SAMP> in the usual way, you will not be able to run it.This is because <SAMP>`$(CC)'</SAMP> will build a program for the host system,but the program is being built on the build system. You must insteaduse a compiler for the build system, rather than the host system. Thiscompiler is conventionally called <SAMP>`$(CC_FOR_BUILD)'</SAMP>.</P><P>A <TT>`configure'</TT> script should normally permit the user to define<SAMP>`CC_FOR_BUILD'</SAMP> explicitly in the environment. Your configurescript should help by selecting a reasonable default value. If the<TT>`configure'</TT> script is not being run with a cross compiler (i.e.,the <SAMP>`cross_compiling'</SAMP> shell variable is <SAMP>`no'</SAMP> after calling<SAMP>`AC_PROG_CC'</SAMP>), then the proper default for <SAMP>`CC_FOR_BUILD'</SAMP> issimply <SAMP>`$(CC)'</SAMP>. Otherwise, a reasonable default is simply<SAMP>`cc'</SAMP>.</P><P>Note that you should not include <TT>`config.h'</TT> in a file you arecompiling with <SAMP>`$(CC_FOR_BUILD)'</SAMP>. The <TT>`configure'</TT> script willbuild <TT>`config.h'</TT> with information for the host system. However,you are compiling the file using a compiler for the build system (anative compiler). Subsidiary programs are normally simple filters whichdo no user interaction, and it is often possible to write them in ahighly portable fashion so that the absence of <TT>`config.h'</TT> is notcrucial.</P><P><A NAME="IDX100"></A>The <CODE>gcc</CODE> <TT>`Makefile.in'</TT> shows a complex situation in whichcertain files, such as <TT>`rtl.c'</TT>, must be compiled into bothsubsidiary programs run on the build system and into the final program.This approach may be of interest for advanced GNU Autotools hackers. Notethat, at least in GCC 2.95, the build system compiler is ratherconfusingly called <SAMP>`HOST_CC'</SAMP>.</P><P><A NAME="Installing GNU Autotools"></A></TR></TABLE><BR> <FONT SIZE="-1">This document was generatedby <I>Gary V. Vaughan</I> on <I>September, 12 2004</I>using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html"><I>texi2html</I></A></BODY></HTML>⌨️ 快捷键说明
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