Merge pull request #19 from KarlK90/feature/cpio-build-target

Add cross compilation and cpio archive targets

Author: michaelolbrich

Makefile

@@ -0,0 +1,73 @@
+# SPDX-FileCopyrightText: 2025 The rsinit Authors
+# SPDX-License-Identifier: GPL-2.0-only
+
+CARGO_RUNNER			?= cross
+CROSS_CONTAINER_ENGINE		 = podman
+MINIMAL_BUILD			?= 0
+
+ifneq ($(MINIMAL_BUILD),0)
+	TARGET_PROFILE	:= minimal
+	RUSTFLAGS		:= -Zfmt-debug=none -Zlocation-detail=none
+	CARGO_FLAGS		:= -Z build-std=std,panic_abort -Z build-std-features=panic_immediate_abort
+else
+	TARGET_PROFILE	?= release
+	RUSTFLAGS		?=
+	CARGO_FLAGS		?=
+endif
+
+default-target-list	:= aarch64-unknown-linux-musl arm-unknown-linux-musleabihf x86_64-unknown-linux-musl
+
+all: check-toolchain build cpio
+build: $(addsuffix -build,$(default-target-list))
+cpio: $(addsuffix -cpio,$(default-target-list))
+
+help:
+	@echo "rsinit cross compilation Makefile"
+	@echo ""
+	@echo "Available targets:"
+	@echo "  help              - Show this help message"
+	@echo "  check-toolchain   - Verify all required CLI tools are installed"
+	@echo "  all               - Build and create CPIO archives for all default targets"
+	@echo "  build             - Build binaries for all default targets"
+	@echo "  cpio              - Create CPIO archives for all default targets"
+	@echo "  <target>-build    - Build for a specific target (e.g., aarch64-unknown-linux-musl-build)"
+	@echo "  <target>-cpio     - Create CPIO archive for a specific target"
+	@echo ""
+	@echo "Default targets: $(default-target-list)"
+	@echo ""
+	@echo "Configuration variables:"
+	@echo "  CARGO_RUNNER           - Cargo wrapper for cross-compilation (default: $(CARGO_RUNNER))"
+	@echo "  CROSS_CONTAINER_ENGINE - Container engine for cross (default: $(CROSS_CONTAINER_ENGINE))"
+	@echo "  MINIMAL_BUILD          - Enable minimal build profile (default: $(MINIMAL_BUILD))"
+	@echo "  TARGET_PROFILE         - Build profile to use (current: $(TARGET_PROFILE))"
+	@echo ""
+	@echo "Examples:"
+	@echo "  make check-toolchain                    - Verify dependencies"
+	@echo "  make all                                - Build everything"
+	@echo "  make aarch64-unknown-linux-musl-build   - Build for aarch64 only"
+	@echo "  make MINIMAL_BUILD=1 all                - Build with minimal profile"
+	@echo "  make CROSS_CONTAINER_ENGINE=docker all  - Use Docker instead of Podman"
+
+check-toolchain:
+	@echo "Checking for required CLI tools..."
+	@command -v $(CARGO_RUNNER) >/dev/null 2>&1 || { echo "Error: $(CARGO_RUNNER) is not installed. Please install it to continue."; exit 1; }
+	@command -v rustup >/dev/null 2>&1 || { echo "Error: rustup is not installed. Please install it from https://rustup.rs/"; exit 1; }
+	@command -v find >/dev/null 2>&1 || { echo "Error: find is not installed."; exit 1; }
+	@command -v cpio >/dev/null 2>&1 || { echo "Error: cpio is not installed. Please install it using your package manager."; exit 1; }
+	@command -v gzip >/dev/null 2>&1 || { echo "Error: gzip is not installed."; exit 1; }
+	@command -v $(CROSS_CONTAINER_ENGINE) >/dev/null 2>&1 || { echo "Error: $(CROSS_CONTAINER_ENGINE) is not installed. Please install podman or set CROSS_CONTAINER_ENGINE to docker."; exit 1; }
+	@rustup toolchain list | grep -q nightly || { echo "Error: nightly toolchain is not installed. Run: rustup toolchain install nightly"; exit 1; }
+	@echo "All required tools are available!"
+
+%-build: check-toolchain
+	CROSS_CONTAINER_ENGINE=$(CROSS_CONTAINER_ENGINE) RUSTFLAGS="$(RUSTFLAGS)" $(CARGO_RUNNER) +nightly build --target $* $(if $(TARGET_PROFILE),--profile $(TARGET_PROFILE)) $(CARGO_FLAGS)
+
+%-cpio: T=target/$*/$(if $(TARGET_PROFILE),$(TARGET_PROFILE),debug)
+%-cpio: %-build
+	cd $T && find init | cpio --create --format=newc > init-$*.cpio
+	cd $T && gzip --keep --best --force init-$*.cpio
+
+clean:
+	cargo clean
+
+.PHONY: all build clean cpio check-toolchain help

README.md

@@ -25,3 +25,59 @@ Currently supported root filesystems are:
    mount options
  * nfsroot
  * 9pfs with virtio transport (for QEMU)
+
+Cross compilation with cross.rs
+-------------------------------
+
+The project includes a Makefile for easy cross-compilation.
+
+### Prerequisites
+
+Before building, ensure you have the following tools installed:
+
+- [`cross`](https://github.com/cross-rs/cross) - Cross-compilation tool for Rust
+- [`rustup`](https://rustup.rs/) - Rust toolchain manager
+- [`podman`](https://podman.io/) or [`docker`](https://www.docker.com/) - Container runtime for cross
+- `cpio` - For creating cpio/initramfs archives
+- `gzip` - For compressing cpio/initramfs archives
+- A `nightly` Rust toolchain
+
+You can verify all dependencies are installed by running:
+
+```bash
+make check-toolchain
+```
+
+### Usage
+
+To see all available make targets and options:
+
+```bash
+make help
+```
+
+Common build commands:
+
+```bash
+# Build binaries and CPIO archives for all default targets
+make all
+
+# Build for a specific target only
+make aarch64-unknown-linux-musl-build
+
+# Create CPIO archive for a specific target
+make aarch64-unknown-linux-musl-cpio
+
+# Build with minimal profile (smaller binary size)
+make MINIMAL_BUILD=1 all
+
+# Use Docker instead of Podman
+make CROSS_CONTAINER_ENGINE=docker all
+```
+
+Default target architectures:
+- `aarch64-unknown-linux-musl`
+- `arm-unknown-linux-musleabihf`
+- `x86_64-unknown-linux-musl`
+
+Build artifacts are placed in `target/<arch>/<profile>/` directories.