fds-os/docs/developer/glossary.md

Glossary

Development reference and historical context. For current operating instructions, use the user manual. Acceptance applies only to the source and artifacts identified in each record.

Documentation index

Term	Meaning in this repository
M0	Milestone zero: prepare and verify the workstation's cross-build environment. M1 adds the rootfs; M2 adds native init and ARM VM boot.
Host / build workstation	The x86_64 Arch Linux computer running the build.
Target	The platform being built for: AArch64 Linux on the Pi.
x86_64	The processor architecture of the supported build workstation.
AArch64 / aarch64 / arm64	Names commonly used for 64-bit ARM. Void uses aarch64 for its glibc package target.
Cross-compilation	Compiling on one platform to produce code for another. An x86_64 build can produce an ARM executable that does not run directly on its host.
Toolchain	Compiler, linker, and related tools used to build software.
Sysroot	Target headers and libraries made available to a cross compiler. It is not necessarily a bootable filesystem.
ABI	Application binary interface: the machine-level conventions that compiled programs and libraries must agree on. Matching CPU architecture alone is insufficient.
libc	The C runtime library. FDS uses glibc for conventional packages and musl inside its static Rust tools.
glibc	GNU's C library, used by the main FDS userspace and Void aarch64 packages.
musl	An alternative C library used for static FDS-owned programs. It does not replace the system's glibc package set.
Static linking	Including needed library code in an executable at build time, so it does not need those shared libraries at startup. It still needs the operating system/kernel.
Dynamic linking / loader	Loading shared libraries when a program starts. The ARM glibc loader is /lib/ld-linux-aarch64.so.1.
ELF	The executable/library file format inspected by file and readelf. The validator checks architecture and runtime requirements.
Rust target triple	A name such as aarch64-unknown-linux-musl specifying the compiler's target platform and library environment.
Cargo / Rustup	Cargo builds Rust projects; Rustup installs/selects Rust toolchains and target components.
QEMU user mode	Executes a foreign-architecture Linux program on the host. It does not boot or emulate the entire Pi in the M0 example.
XBPS	Void's package-management tools and package format, reused by FDS. It is separate from Arch's pacman.
xbps-src	Void's source-package build system. It creates packages using recipes called templates.
Template	An xbps-src package recipe describing source, dependencies, build actions, and packaging.
Submodule / gitlink	A separate Git repository embedded at a path; the parent records the exact upstream commit it expects.
Pin	An explicit version, commit, or digest chosen for an input. A source pin alone does not freeze every downloaded dependency.
Overlay	An FDS-owned package directory copied into the build tree without modifying tracked upstream packages.
masterdir	The generated Void build-container filesystem under vendor/void-packages/masterdir-x86_64/. This is not the target OS root.
hostdir	xbps-src's generated cache/output directory under vendor/void-packages/hostdir/.
bubblewrap / bwrap	The host tool used to isolate the build environment with Linux namespaces and mounts. No target init system runs inside this M0 container.
Manifest	A generated record of package versions or file checksums used to inspect a particular build.
Rootfs	The root filesystem used by a running OS, including programs, libraries, and configuration. make rootfs builds its archive.
Initramfs	A small early userspace filesystem loaded with the kernel, used before switching to the main root filesystem.
PID 1 / init	The first userspace process and the foundation of system startup, supervision, and shutdown. FDS uses native s6.
s6 / s6-rc	FDS's process-supervision and service-dependency tools. The service database is compiled while building the image.
EROFS	The read-only filesystem format used for SYSTEM and recovery images.
tmpfs	A memory-backed filesystem for temporary state. Its contents do not persist through power loss.
GPT / PARTNAME	Disk partition metadata and a partition's name. Stage0 discovers SYSTEM using FDS_SYSTEM, rather than a changing /dev/sdX name.
NVMe	The internal solid-state storage interface/device. The FDS internal image holds boot, recovery, and machine configuration.
SYSTEM / DATA	Cartridge roles: operating-system image and persistent user files, respectively.
PROGRAM / ENVIRONMENT	Cartridge roles: application payload and activation/configuration of a known environment.
Bay topology	Mapping a physical USB hub/port path to the user-facing BAY 01–12 labels.
Hotplug	Inserting or removing a device while the machine is running. Detection does not by itself make removal safe.
sysfs / netlink	Linux interfaces used by FDS to inspect devices and receive cartridge events.
Profile	A known OS configuration or service selection activated by a cartridge. It is not an arbitrary root script supplied by media.
Safe eject	Stopping users of a cartridge, flushing pending writes, unmounting it, then reporting it safe to remove. Use fds eject BAY.

For how these pieces fit together, read Architecture. For commands that currently work, follow Your first build.