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Arrows point from the caller to the provider or dependency. Labels distinguish function calls, IPC, streams and launches; dashed arrows identify headers, discovery topics or optional paths.

System foundation

flowchart TB
    clients(["Applications/userspace libraries"])
    libc["libc"]
    libapi["libapi"]
    kernel[["kernel"]]
    compiler["C++ / GCC support"]
    musl["libm (bundled musl)"]

    clients -->|"default -lc"| libc
    clients -->|"default -lghostapi"| libapi
    clients -->|"C++ final-link support"| compiler
    libc -->|"syscall wrappers"| libapi
    libapi -->|"allocation/memory functions"| libc
    libc -->|"bundles"| musl
    libapi -->|"int 0x80 syscalls"| kernel
    kernel -.->|"C-compatible ABI headers"| libapi
    kernel -.->|"ELF definitions from elf.h"| libc

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class clients callers

The kernel links freestanding and uses shared headers from libapi. Its ELF loader also uses libc’s elf.h definitions, without linking libc. Kernel code includes no application headers. Static archives defer symbol resolution to their consumers; libc supplies the math functions behind the empty compatibility libm archive.

Filesystem access

flowchart TB
    apps(["Applications"])
    libc["libc"]
    libapi["libapi filesystem API"]
    vfs[["kernel VFS"]]
    ramdisk[["kernel ramdisk"]]
    fat["fatdriver"]
    storage["Block storage"]

    apps -->|"POSIX file operations"| libc
    apps -->|"direct filesystem API"| libapi
    libc -->|"wrappers"| libapi
    libapi -->|"syscalls"| vfs
    vfs -->|"built-in backend"| ramdisk
    vfs -->|"delegate requests & shared pages"| fat
    fat -->|"sector I/O"| storage

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

The VFS selects the mount’s backend. FAT requests go to a userspace delegate; ramdisk operations stay inside the kernel. The live system uses the ramdisk, while an installed system mounts its selected FAT boot volume as root. See Filesystem for the delegate contract and the next section for the block-storage path.

Volumes and block storage

flowchart TB
    apps(["Storage tools"])
    volumes["libstorage"]
    manager["storagemanager"]
    fat["fatdriver"]
    blocks["libblockdevice"]
    ahci["ahcidriver"]
    definitions["libahci"]
    devices["Device discovery"]

    apps -->|"disk/volume queries and administration"| volumes
    apps -->|"raw block operations"| blocks
    volumes -->|"IPC requests"| manager
    fat -->|"claims and formatter registration"| volumes
    manager -->|"mount / flush / unmount / format"| fat
    fat -.->|"volume topic"| manager
    manager -.->|"device topic"| devices
    manager -->|"partition-table I/O"| blocks
    fat -->|"filesystem sector I/O"| blocks
    blocks -->|"block IPC and shared DMA buffers"| ahci
    ahci -.->|"hardware definitions"| definitions

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

storagemanager administers disks and partitions, coordinates exclusive volume ownership and dispatches filesystem control jobs. fatdriver serves FAT12/16/32 and formats FAT32 volumes. libblockdevice accepts the announced driver endpoint; AHCI is the block provider in this checkout. AHCI’s PCI access and device registration are shown in the device-discovery section.

Device discovery and PCI

flowchart TB
    clients(["Applications and hardware drivers"])
    devices["libdevice"]
    manager["devicemanager"]
    pci["libpci"]
    driver["pcidriver"]

    clients -->|"device registration and queries"| devices
    devices -->|"IPC"| manager
    clients -.->|"device topic"| manager
    clients -->|"PCI enumeration and configuration"| pci
    manager -->|"controller selection"| pci
    pci -->|"PCI IPC"| driver

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class clients callers

Hardware drivers register their serving task and device ID through libdevice. devicemanager publishes registrations on the replayable device topic. libpci wraps pcidriver’s protocol, whose shared C-compatible definitions live in libapi. Kernel power code and acpidriver use that protocol directly.

Windowing and display

flowchart TB
    apps(["Graphical applications"])
    client["libfenster"]
    server["ƒenster window server"]
    video["libvideo"]
    efi["efifbdriver"]
    svga["vmsvgadriver"]
    devices["Device discovery"]

    apps -->|"UI API"| client
    client -->|"UI messages and shared buffers"| server
    server -.->|"video device topic"| devices
    server -->|"mode and framebuffer operations"| video
    video -->|"selected EFI endpoint"| efi
    video -->|"selected VMware endpoint"| svga

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

Graphical clients communicate with ƒenster through libfenster. The server selects a discovered video endpoint; the hardware driver owns mode changes and shared framebuffer access. Input handling and graphics-library dependencies have their own views below. vmsvgadriver also uses libpci, and both video drivers register through libdevice.

Input and terminals

Keyboard and mouse

flowchart TB
    consumers(["Input consumers"])
    client["libps2driver"]
    driver["ps2driver"]
    controller["libps2"]
    input["libinput"]
    properties["libproperties"]

    consumers -->|"initialize input"| client
    client -->|"IPC / obtain input pipes"| driver
    consumers -->|"decode input and translate keys"| input
    input -->|"read keyboard and mouse pipes"| driver
    input -->|"keyboard layout configuration"| properties
    driver -->|"controller operations"| controller
    input -.->|"packet definitions"| client

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class consumers callers

ƒenster and the headless terminal initialize PS/2 input through libps2driver. libinput decodes pipe data and loads keyboard layouts through libproperties. The graphical terminal receives input through ƒenster.

Terminal sessions

flowchart LR
    apps(["Terminal programs"])
    client["libterminal"]
    terminal["terminal"]

    apps -->|"stdin / stdout streams"| terminal
    apps -->|"terminal control helpers"| client
    client -->|"escape and control stream"| terminal

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

Terminal programs use inherited stdio; terminal-specific helpers add cursor, input-mode and control operations over that stream. terminal starts gsh with redirected descriptors. Its graphical frontend uses libfenster; its headless frontend uses the input pipeline above.

Firmware and power

flowchart TB
    apps(["Applications"])
    api["libapi power API"]
    kernel[["Kernel power coordinator"]]
    acpi["acpidriver"]
    interpreter["Bundled uACPI"]
    pci["pcidriver"]
    participants["Registered power participants"]
    queries["libacpi"]

    apps -->|"shutdown / reboot"| api
    api -->|"syscalls"| kernel
    kernel -->|"ACPI info / prepare / cancel"| acpi
    kernel -->|"PCI power configuration"| pci
    kernel -->|"prepare and quiesce"| participants
    acpi -->|"firmware interpreter"| interpreter
    acpi -->|"PCI configuration IPC"| pci
    queries -->|"ACPI info queries"| acpi

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

Power coordination uses the PCI/ACPI protocols defined in libapi. The current registered participants are pcidriver (platform), ahcidriver (storage) and editor (application). libacpi provides an information-query helper, although no current production target explicitly links it. See Shutdown and reboot.

Graphics libraries

flowchart TB
    clients(["Graphics consumers"])
    ui["libfenster"]
    cairo["Cairo"]
    fonts["FreeType"]
    pixels["Pixman"]
    png["libpng"]
    zlib["zlib"]

    clients -->|"declared graphics links"| cairo
    clients --> fonts
    clients --> pixels
    clients --> png
    clients --> zlib
    ui -.->|"public graphics types"| cairo
    ui -.->|"font types"| fonts
    cairo --> fonts
    cairo --> pixels
    cairo --> png
    cairo --> zlib
    fonts --> zlib
    png --> zlib

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class clients callers

The graphics link set is used by ƒenster, editor, navigator and terminal. FreeType and libpng use zlib; Cairo and Pixman also use libc’s math functions. The installed Cairo script interpreter is a companion port with no project consumer. Other bundled implementations are musl in libc, uACPI in acpidriver and Duktape in the js interpreter.

Service startup

flowchart TB
    kernel[["Kernel"]]
    platform["Platform services"]
    manager["devicemanager"]
    storage["Storage services"]
    video["Selected video driver"]
    server["ƒenster"]
    desktop["navigator"]
    apps(["User-selected applications"])

    kernel -->|"PCI / ACPI / PS2 services"| platform
    kernel -->|"device manager"| manager
    kernel -->|"window server"| server
    manager -->|"AHCI / storage manager / FAT worker"| storage
    manager -->|"EFI framebuffer or VMware SVGA"| video
    server -->|"desktop"| desktop
    desktop -->|"launchers and executable files"| apps

    classDef callers fill:#f3f4f6,stroke:#718096,color:#172b3d
    class apps callers

Platform services are pcidriver, acpidriver and ps2driver; storage services are ahcidriver, storagemanager and fatdriver. Navigator launches user-selected programs. terminal starts gsh, which launches commands and pipelines. Navigator can also forward later invocations to the existing desktop instance. The Doom launcher references an optional binary absent from the current source/build targets.

Exact build reference

Per-component library links and additional source/header dependencies

Common libc/libapi/C++ dependencies apply to all userspace targets. The additional direct dependencies are listed here; static archives resolve symbols at their final consumer’s link step.

Component Declared library links Additional source/header dependencies

acpidriver

—

uACPI (bundled)

ahcidriver

libdevice, libpci

libahci, libblockdevice

calculator

libfenster, libinput, libproperties

—

devicemanager

libpci

libdevice

editor

Cairo, FreeType, Pixman, libfenster, libinput, libpng, libproperties, zlib

—

efifbdriver

libdevice

libvideo

fatdriver

libblockdevice, libstorage

—

ƒenster (target: fenster)

Cairo, FreeType, Pixman, libfenster, libinput, libpng, libproperties, libps2driver, libvideo, zlib

—

gsh

libterminal

—

install

libblockdevice, libfenster, libstorage

—

js

—

Duktape (bundled), libterminal

navigator

Cairo, FreeType, Pixman, libfenster, libinput, libpng, libproperties, zlib

—

pcidriver

—

libpci

ps2driver

libps2

libps2driver

terminal

Cairo, FreeType, Pixman, libfenster, libinput, libpng, libproperties, libps2driver, libterminal, zlib

—

tester (source: testprogram)

libfenster, libps2driver

—

vmsvgadriver

libdevice, libpci

libfenster, libvideo

storagemanager

libblockdevice

libstorage

blockdevice (core)

libblockdevice

—

copy (core)

—

—

device (core)

libdevice

—

disk (core)

libstorage

—

echo (core)

—

—

lines (core)

—

—

ls (core)

—

—

process (core)

—

—

read (core)

—

—

reverse (core)

—

—

topic (core)

—

—

volume (core)

libstorage

—

write (core)

—

—

libacpi

—

—

libahci

—

—

libblockdevice

—

libdevice

libdevice

—

—

libfenster

—

Cairo, FreeType, libinput

libinput

—

libproperties, libps2driver

libpci

—

—

libproperties

—

—

libps2

—

—

libps2driver

—

—

libterminal

—

—

libvideo

—

libdevice

libstorage

—

libdevice