CODEWITHSUNDEEP
makefilecross-compilingconfigure
exebook
exebook

Reputation: 33950

When/how to specify configure/make target

Large variety of open-source projects are distributed in source-code and supposed to be compiled with ./configure && make approach. But if I want to cross-compile, at which of those two steps I am supposed to tell them what target platform I want to get the binary?

Does it have to do with configure/make in general, or this is specific to every project? What could be an example of compiling some project, library or console application and specifying target?

I know many projects have a web-page on their websites that is dedicated to "cross compiling this program". So it seems to be project-specific setting. But the project still uses configure/make, so what is the relation of all that?

Upvotes: 4

Views: 3850

Answers (1)

MadScientist
MadScientist

Reputation: 100986

If your system is using standard GNU autoconf, then you would always define the cross-compilation at configure time, not at make time. If the configure script does not know you're cross-compiling it may obtain incorrect answers when it probes the system looking for what is supported and what is not supported.

Cross-compilation is what the --build, --host, and --target flags to configure are for. You should never need to set --build: it always refers to the system you're running configure on, and configure can figure that out for itself. For a normal cross-compilation you also do not set --host, and you would set --target to the cross-compilation target. You may also need to set the CC (for C programs) and/or CXX (for C++ programs), LD, AR, STRIP, and a few others, if needed. Personally I prefer to build in a separate directory as well, although some packages don't support it unfortunately):

tar xzf foo-1.1.tar.gz
mkdir obj
cd obj
../foo-1.1/configure --target=... CC=...-gcc CXX=...-g++ ...
make

Note this is all provided by basic autoconf / automake, so all projects will do it the same way (although in my experience many projects which do not attempt cross-compilation somewhat regularly, do something wrong such that it doesn't work so well).

Upvotes: 5

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