building.md

Building nonlibc

Build with Nix

Nix takes care of all the dependencies; from the project top-level directory:

nix-build

If including nonlibc as a dependency for another nix package, extend NIX_PATH to include the parent directory of this repo using the -I flag.

Here is an example from the memorywell library, which depends on nonlibc:

cd ~
git clone https://github.com/siriobalmelli/nonlibc.git
git clone https://github.com/siriobalmelli/memorywell.git
cd memorywell
nix-build -I ~

Build with Meson

You will need to have a few dependencies installed on your system:

• python3
• meson
• ninja
• pandoc
• a suitable C compiler (gcc and clang are tested)

Run make check - chances are things will work automagically and you'll find yourself with everything built and all tests running.

I'm on Windows || It doesn't work

Don't despair; if you can get the dependencies above to install, things might still work with some manual twiddling:

meson --buildtype debugoptimized build-debug \
&& cd build-debug \
&& ninja test

... and if it still won't work, drop me a line at [email protected].

I want to link my program against this library

Here's a few scenarios to get you acquainted:

Using Nix

In your derivation, add a nonlibc dependency.

Here is an example from the memorywell library:

{ 	# deps
	system ? builtins.currentSystem,
	nixpkgs ? import <nixpkgs> { inherit system; },
	nonlibc ? import <nonlibc> { inherit system;
								inherit buildtype;
								inherit compiler;
								inherit lib_type;
								inherit dep_type;
								inherit mesonFlags;
	},
	# options
	buildtype ? "release",
	compiler ? "clang",
	lib_type ? "shared",
	dep_type ? "shared",
	mesonFlags ? ""
}:

with nixpkgs;

stdenv.mkDerivation rec {
	name = "memorywell";
	outputs = [ "out" ];

	# build-only deps
	nativeBuildInputs = [
		(lowPrio gcc)
		clang
		clang-tools
		cscope
		meson
		ninja
		pandoc
		pkgconfig
		python3
		valgrind
		which
	];

	# runtime deps
	buildInputs = [
		nonlibc
	];

	# just work with the current directory (aka: Git repo), no fancy tarness
	src = ./.;

	# Override the setupHook in the meson nix derviation,
	# so that meson doesn't automatically get invoked from there.
	meson = pkgs.meson.overrideAttrs ( oldAttrs: rec {
		setupHook = "";
	});

	# build
	mFlags = mesonFlags
		+ " --buildtype=${buildtype}"
		+ " -Dlib_type=${lib_type}"
		+ " -Ddep_type=${dep_type}";

	configurePhase = ''
		echo "flags: $mFlags"
		echo "prefix: $out"
		CC=${compiler} meson --prefix=$out build $mFlags
		cd build
		'';

	buildPhase = "ninja";
	doCheck = true;
	checkPhase = "ninja test";
	installPhase = "ninja install";
}

Using pkg-config

make
sudo make install

To verify things are kosher, check if you get some useful output from:

pkg-config --modversion nonlibc

Et voilà - if your build system uses pkg-config it will see nonlibc and link against it.

If you're using Meson to build your project, insert the following stanza in your meson.build file:

nonlibc = dependency('nonlibc')

... and then add the dependencies : nonlibc stanza to the executable declaration(s) in your meson.build file(s); e.g.:

executable('demo', 'test.c', dependencies : nonlibc)

I want to statically include this library in my program

This is a very good idea:

• The build system won't have to build position-independent code which will give a measurable speedup.
• Compiler can discard unused objects and reduce memory footprint.

If you also build your project with Meson, I recommend you symlink the nonlibc repo into the subprojects directory:

pushd ~
git clone https://github.com/siriobalmelli/nonlibc.git
popd
mkdir -p subprojects
ln -s ~/nonlibc subprojects/

Add the following line to your toplevel meson.build file:

nonlibc = dependency('nonlibc', fallback : ['nonlibc', 'nonlibc_dep'])

• Add the dependencies : nonlibc stanza to the executable declaration(s) in your meson.build file(s); e.g.:

executable('demo', 'test.c', dependencies : nonlibc)

Cross-platform

Happily builds and tests cleanly on a 32-bit ARM machine running Debian.

We still depend on a bunch of libc symbols at link-time, though (oh, the irony).

Cross-compilation

Cross compilation is tentatively tested for ARM so far, using cross_arm.txt:

meson --cross-file=toolchain/cross_arm.txt --buildtype=plain build-arm
cd build-arm
ninja