Build System¶

ELMOS uses Task for build automation and Go's domain builders for kernel/module/app compilation.

Taskfile Overview¶

The Taskfile.yml provides development tasks:

Task	Purpose
`task build`	Compile `build/elmos` with version ldflags
`task test`	Run tests with coverage
`task dev:check`	Format + lint
`task docs`	Build documentation site
`task release:all`	Cross-platform Darwin builds

Kernel Build System¶

KernelBuilder¶

Located in core/domain/builder/kernel.go:

type KernelBuilder struct {
    exec executor.Executor
    fs   filesystem.FileSystem
    cfg  *config.Config
    ctx  *elcontext.Context
    tm   *toolchain.Manager
}

BuildOptions¶

type BuildOptions struct {
    Jobs    int      // Parallel jobs (-j)
    Targets []string // e.g., ["Image", "dtbs", "modules"]
}

Key Methods¶

Method	Description
`Build(ctx, opts)`	Execute `make` with targets
`Configure(ctx, configType)`	Run menuconfig, defconfig, etc.
`Clean(ctx)`	Run `make distclean`
`HasConfig()`	Check if `.config` exists
`HasKernelImage()`	Check if kernel image built

Build Flow¶

KernelBuilder.Build()
    ├── Validate targets against ValidBuildTargets
    ├── Get toolchain environment (getToolchainEnv)
    ├── Construct make arguments:
    │   - ARCH=arm64
    │   - LLVM=1
    │   - CROSS_COMPILE=<prefix>
    │   - -j<jobs>
    └── executor.RunWithEnv(make, args...)

Module Build System¶

ModuleBuilder¶

Located in core/domain/builder/module.go:

type ModuleBuilder struct {
    exec executor.Executor
    fs   filesystem.FileSystem
    cfg  *config.Config
    ctx  *elcontext.Context
    tm   *toolchain.Manager
}

Key Methods¶

Method	Description
`Build(ctx, modulePath)`	Build `.ko` from module source
`Clean(ctx, modulePath)`	Clean module build artifacts
`Create(name)`	Scaffold new module from template

App Build System¶

AppBuilder¶

Located in core/domain/builder/app.go:

type AppBuilder struct {
    exec executor.Executor
    fs   filesystem.FileSystem
    cfg  *config.Config
    ctx  *elcontext.Context
    tm   *toolchain.Manager
}

Cross-compiles userspace applications for the target architecture.

Environment Setup¶

GetMakeEnv()¶

The Context.GetMakeEnv() method constructs the build environment:

// Prepends to PATH:
// - GNU sed (libexec/gnubin)
// - GNU coreutils
// - LLVM bin
// - LLD bin
// - e2fsprogs sbin

// Sets:
// - ARCH=<target>
// - LLVM=1
// - CROSS_COMPILE=<prefix>
// - HOSTCFLAGS=<macOS compatibility flags>

HOSTCFLAGS¶

macOS-specific flags for host tools:

-I<assets/libraries>     # Custom elf.h, byteswap.h
-I<libelf include>       # Homebrew libelf
-D_UUID_T
-D__GETHOSTUUID_H
-D_DARWIN_C_SOURCE
-D_FILE_OFFSET_BITS=64

Valid Build Targets¶

Defined in core/config/defaults.go:

var ValidBuildTargets = map[string]bool{
    "Image":           true,
    "zImage":          true,  // ARM32
    "dtbs":            true,
    "modules":         true,
    "modules_prepare": true,
    "all":             true,
    "vmlinux":         true,
}

Valid Config Types¶

var KernelConfigTypes = []string{
    "defconfig",
    "tinyconfig",
    "kvm_guest.config",
    "menuconfig",
    "xconfig",
    "nconfig",
    "oldconfig",
    "olddefconfig",
    // ...
}

CLI Integration¶

Build Command¶

elmos kernel build              # Default targets for arch
elmos kernel build Image        # Specific target
elmos kernel build -j 8         # Custom job count

Configure Command¶

elmos kernel config defconfig   # Default config
elmos kernel config menuconfig  # Interactive

Dependencies¶

Go 1.21+ - Language runtime
Task - brew install go-task
LLVM - Cross-compiler (brew install llvm)
GNU tools - brew install gnu-sed coreutils