Follow Techotopia on Twitter

On-line Guides
All Guides
eBook Store
iOS / Android
Linux for Beginners
Office Productivity
Linux Installation
Linux Security
Linux Utilities
Linux Virtualization
Linux Kernel
System/Network Admin
Scripting Languages
Development Tools
Web Development
GUI Toolkits/Desktop
Mail Systems
Eclipse Documentation

How To Guides
General System Admin
Linux Security
Linux Filesystems
Web Servers
Graphics & Desktop
PC Hardware
Problem Solutions
Privacy Policy




Back: Supporting Cross Compiler in Configure
Forward: Installing GNU Autotools
FastBack: Cross Compilation
Up: Supporting Cross Compiler
FastForward: Installing GNU Autotools
Top: Autoconf, Automake, and Libtool
Contents: Table of Contents
Index: Index
About: About this document Supporting Building with a Cross Compiler in Makefiles

The main cross compiling issue in a `Makefile' arises when you want to use a subsidiary program to generate code or data which you will then include in your real program. If you compile this subsidiary program using `$(CC)' in the usual way, you will not be able to run it. This is because `$(CC)' will build a program for the host system, but the program is being built on the build system. You must instead use a compiler for the build system, rather than the host system. This compiler is conventionally called `$(CC_FOR_BUILD)'.

A `configure' script should normally permit the user to define `CC_FOR_BUILD' explicitly in the environment. Your configure script should help by selecting a reasonable default value. If the `configure' script is not being run with a cross compiler (i.e., the `cross_compiling' shell variable is `no' after calling `AC_PROG_CC'), then the proper default for `CC_FOR_BUILD' is simply `$(CC)'. Otherwise, a reasonable default is simply `cc'.

Note that you should not include `config.h' in a file you are compiling with `$(CC_FOR_BUILD)'. The `configure' script will build `config.h' with information for the host system. However, you are compiling the file using a compiler for the build system (a native compiler). Subsidiary programs are normally simple filters which do no user interaction, and it is often possible to write them in a highly portable fashion so that the absence of `config.h' is not crucial.

The gcc `' shows a complex situation in which certain files, such as `rtl.c', must be compiled into both subsidiary programs run on the build system and into the final program. This approach may be of interest for advanced GNU Autotools hackers. Note that, at least in GCC 2.95, the build system compiler is rather confusingly called `HOST_CC'.

This document was generated by Gary V. Vaughan on February, 8 2006 using texi2html

  Published under the terms of the Open Publication License Design by Interspire