automake-1.16: Cross-Compilation
2.2.8 Cross-Compilation
-----------------------
To “cross-compile” is to build on one platform a binary that will run on
another platform. When speaking of cross-compilation, it is important
to distinguish between the “build platform” on which the compilation is
performed, and the “host platform” on which the resulting executable is
expected to run. The following ‘configure’ options are used to specify
each of them:
‘--build=BUILD’
The system on which the package is built.
‘--host=HOST’
The system where built programs and libraries will run.
When the ‘--host’ is used, ‘configure’ will search for the
cross-compiling suite for this platform. Cross-compilation tools
commonly have their target architecture as prefix of their name. For
instance my cross-compiler for MinGW32 has its binaries called
‘i586-mingw32msvc-gcc’, ‘i586-mingw32msvc-ld’, ‘i586-mingw32msvc-as’,
etc.
Here is how we could build ‘amhello-1.0’ for ‘i586-mingw32msvc’ on a
GNU/Linux PC.
~/amhello-1.0 % ./configure --build i686-pc-linux-gnu --host i586-mingw32msvc
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for i586-mingw32msvc-strip... i586-mingw32msvc-strip
checking for i586-mingw32msvc-gcc... i586-mingw32msvc-gcc
checking for C compiler default output file name... a.exe
checking whether the C compiler works... yes
checking whether we are cross compiling... yes
checking for suffix of executables... .exe
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether i586-mingw32msvc-gcc accepts -g... yes
checking for i586-mingw32msvc-gcc option to accept ANSI C...
...
~/amhello-1.0 % make
...
~/amhello-1.0 % cd src; file hello.exe
hello.exe: MS Windows PE 32-bit Intel 80386 console executable not relocatable
The ‘--host’ and ‘--build’ options are usually all we need for
cross-compiling. The only exception is if the package being built is
itself a cross-compiler: we need a third option to specify its target
architecture.
‘--target=TARGET’
When building compiler tools: the system for which the tools will
create output.
For instance when installing GCC, the GNU Compiler Collection, we can
use ‘--target=TARGET’ to specify that we want to build GCC as a
cross-compiler for TARGET. Mixing ‘--build’ and ‘--target’, we can
cross-compile a cross-compiler; such a three-way cross-compilation is
known as a “Canadian cross”.
⇒Specifying the System Type (autoconf)Specifying Names, for
more information about these ‘configure’ options.