G1OS software stack

G1OS is the operating system on the Raspberry Pi inside the printer. It is a fork of MainsailOS, with a layer of Ginger-specific configuration installed on top.

Knowing what is in that stack matters when something breaks: most of it is standard software with a large community behind it, and only a small part is specific to the G1.

What runs on the Pi

Service	What it does
klipper	The motion and heating firmware. A Ginger fork of Klipper
moonraker	The API between Klipper and everything else. Listens on port 7125
mainsail	The web interface you open in a browser
KlipperScreen	The interface on the printer’s own display. Also a Ginger fork
crowsnest	Serves the camera stream
sonar	Keeps the Wi-Fi connection from going idle
g1-flask	Ginger’s own configurator. Listens on port 5000 — see below

Alongside those, the image installs timelapse, KAMP (adaptive purge and mesh), Kiauh and Obico support.

Two boards, two USB connections

Klipper talks to two MCUs: the main board and a separate extruder board. The three barrel heaters, the probe servo, the part fan and the feeder switch are on the extruder board — which is why a fault there takes out several unrelated-looking things at once. The bed heater and all the temperature sensing stay on the main board, so the bed keeps working when the extruder board does not. See Klipper MCU extruder_board.

The configurator on port 5000

This is the part that is entirely Ginger’s, and it is the reason the Mainsail menu has entries that do not exist on other Klipper machines.

It runs as the system service g1-flask, checks for updates once an hour, and adds its own entries to Mainsail’s navigation. UPDATE G1 is where configuration updates are applied.

by Ginger Additive is not a status. It sits at the bottom of the sidebar permanently, next to UPDATE G1 rather than instead of it, so seeing it tells you nothing about whether the machine is up to date.

Full explanation of what it updates, and how that differs from the Update Manager: Klipper firmware update.

Where the configuration lives

Everything Klipper reads is under printer_data/config:

File	What it holds
printer.cfg	This machine’s hardware: steppers, heaters, probe, limits. Specific to your printer
moonraker.conf	API settings and the Update Manager entries
kamp.cfg	Adaptive meshing and purging
G1-Configs/	A link to the shared Ginger layer — see below

The G1-Configs/ entry is a symbolic link, not a folder. It points at the repository cloned into the Pi’s home directory, and it carries the parts that are the same on every G1:

• main.cfg — the START_PRINT and END_PRINT sequences
• macro.cfg — every Ginger macro
• mainsail.cfg — interface-side definitions
• KlipperScreen.conf — the display’s configuration

Editing the linked files edits the shared layer

Files under G1-Configs/ are not yours — they are the shared configuration, replaced whenever that layer updates. Anything you need to keep belongs in printer.cfg.

The printer’s serial number is stored separately, in printer_data/database/G1.Conf. That file is what ties the machine to its own configuration; it is written when you run INITIALIZE PRINTER after a fresh install.

The macros the interface calls

The buttons in Mainsail’s Macros panel are ordinary G-code macros:

Macro	What it does
BED_LEVEL	Probes the bed and builds the mesh. Results appear under Heightmap
SCREW_ADJUSTMENT	Walks you through levelling by hand, screw by screw
CHANGE_MATERIAL	A guided six-step material change
CHANGE_NOZZLE	A guided nozzle change — refuses to start while a print is running
EXTRUDER_ROTATION_DISTANCE	Sets Rotation Volume for the screw (E0)
MIXING_STEPPER_ROTATION_DISTANCE	The same for the hopper auger (E1)
SET_PRESSURE_ADVANCE_AND_SMOOTH_TIME	Sets both Pressure Advance values at once

Macros whose names begin with _GINGER_ are internal steps — buzzer tones, probe up and down, purge parking, feeder enable and disable. They are called by the macros above and are not meant to be run by hand.

What the pellet fork actually changes

Klipper on the G1 is a fork, but the pellet-specific part of it is small and worth knowing exactly, because everything else behaves like standard Klipper:

• Pressure Advance smoothing can go far higher. Stock Klipper caps pressure_advance_smooth_time at 0.2 s; the fork raises the ceiling to 5 s. Pellet extrusion needs it — the values the G1 uses would simply be rejected by an unmodified Klipper. The printer’s own display caps the same setting at 1 s
• Bed screw adjustment is not tied to a standard thread. Stock Klipper asks which metric thread the levelling screws use (M3, M4, M5, M6) and derives the correction from a fixed table. The fork replaces that with a configurable factor and direction, because the G1’s screws are not one of those threads

Everything else — motion planning, heater control, the G-code interpreter — is upstream Klipper.

«Up to date» means up to date with the fork

When the Update Manager reports klipper: up-to-date, it means current with Ginger’s fork, not with the Klipper project. The two are not the same thing, and the fork intentionally lags upstream.

Related notes

• Klipper firmware update — the two different updates
• G1OS installation — flashing a fresh card
• Raspberry Pi and SD card
• Mainsail dashboard basics
• Klipper MCU extruder_board