Bootstrap facilities for eweOS

This set of scripts aim to provide automatic bootstrap facilities for eweOS.

Packages need to be bootstrapped

• base and base-devel: Supported
• python packages: TODO
• rust: Cross-compilation only
• ghc: TODO
• golang: TODO
• ... and more?

Overview of base/base-devel bootstrap

The process is split into four stages,

• stage0: Cross-compiled. Compile tools to run on build platform. Currently an eweOS-like system is assumed, thus the only target in stage0 is a LLVM toolchain without runtime libraries.
• stage1: Cross-compiled. Compile C/C++ libraries, native toolchain, and basic POSIX-compilant environment to run on host platform.
• stage2: Compile natively in rootfs produced by stage1, artifacts are installed directly into the rootfs. Compile base/base-devel components which aren't covered by stage1, to produce a rootfs fully equivalent to base/base-devel.
• stage3: Compile natively in rootfs produced by stage1 with additional packages produced by stage2. Compile all base/base-devel packages from eweOS mainline, artifacts are in pacman format (*.pkg.tar.*).

stage1 and stage2 are intentionally separated to minimize cross-compilation for easier maintanence.

The first three stages are driven by GNU Makefiles, to build them, run

# There's no need to manually build stage0, stage1 targets claim dependencies
# to it.
make build/stage1

or

make build/stage2

stage3 build is driven by stage3/build.sh, which pulls PKGBUILD from eweOS mainline repository and run makepkg on them.

A list of packages in base and base-devel is available at stage3/packages. To build all of them, run

mkdir stage3-built
cd stage3-buil

while read pkg; do
	../stage3/build.sh https://github.com/eweOS/packages.git "$pkg" ||
		break
done < ../stage3/packages

stage3/build.sh applies stage3/<PKGNAME>.patch if it exists when building a package, which is useful if patching mainline build scripts is necessary for breaking dependency loops or minimizing dependencies.

Overview of Rust bootstrap

It's separated into three stages,

1. Bootstrapping rustc with help of mrustc, which is a Rust compiler written in C++. This step would probably be only maintained for x86_64. TODO.
2. Cross-compiling Rustc from one architecture to another. Available.
3. Automatically lifting Rust versions. TODO.

Related scripts are located in rust/.

Cross-compiling Rustc

rust/cross-build.sh serves for the purpose, which accepts three arguments,

# Provide absolute path for <TARGET_ROOTFS>
./cross-build.sh <TARGET_ARCH> <RUSTC_VERSION> <TARGET_ROOTFS>

and respects JOBS environment variable.

This script automatically downloads rustc sources, wraps clang as a C/C++ compiler on <TARGET_ROOTFS>, generates config.toml bootstrapping configuration for rustc, and builds it. Patches (ended with .patch) in rust/patches/<RUSTC_VERSION> will be applied to rustc source before building.

The following packages must be available on the build side,

• rustc: Please note that rustc could only be bootstrapped with compiler exactly one version earlier or with the same version.
• qemu-user for <TARGET_ARCH>: Required for wrapping target llvm-config.
• zstd
• curl
• llvm

The following packages must be available on the build/target rootfs,

• llvm