gen1recomp/docs/switch-build.md

Build the Nintendo Switch NRO — contributor guide

Want to play a release build instead? Download the SD-ready zip and extract it at your microSD root — see switch-install.md.

This guide is for contributors who build Gen1Recomp for Switch from source. Hardware evidence, MTP operator loops, and deeper notes live in switch-development.md.

Releases ship gen1recomp-*-switch.zip (SD tree under switch/gen1recomp/; issue #531). Hardware evidence: OLED (author) and V1 boot (community). See switch-development.md for known limitations.

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Prerequisites by OS

All packaging entrypoints are bash. On Windows, use Git Bash, MSYS2, or WSL — not cmd.exe or PowerShell (AD-008).

macOS / Linux

1. Install devkitPro pacman.

2. Install Switch tools:

   sudo dkp-pacman -S switch-dev
   

3. Ensure nacptool and elf2nro are on PATH (or under $DEVKITPRO/tools/bin — the fused script prepends that when set).

Optional: Install Docker so fused builds can fall back to the pinned image when native tools are missing.

Windows (Git Bash / MSYS2 / WSL)

1. Use a bash environment:
   • MSYS2 with the devkitPro packages (preferred for native nacptool/elf2nro), or
   • WSL (Ubuntu/etc.) with the Linux pacman flow above, or
   • Git Bash for --fetch / --loose; for --fused prefer MSYS2 or WSL if Docker bind-mounts from Git Bash paths misbehave.
2. Install switch-dev (or rely on Docker fallback — see below).
3. Do not expect scripts/build_switch.sh to run under cmd/PowerShell.

What you must install yourself

You install	Script does not install
bash, git, zip tooling the repo already expects	—
dkp-pacman + switch-dev (native fused)	dkp-pacman -S …
Docker (optional fused fallback)	Docker Engine
A legal .gb ROM (to play)	Any ROM or game data

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Mode glossary

scripts/build_switch.sh supports three modes (combinable as noted):

Mode	What it does
--fetch	Downloads pinned love.nro + love.elf into .bazinga/love-nx/11.5-nx1/ and verifies SHA-256 against scripts/switch/love-nx-11.5-nx1.sha256.
--loose	Packs game.love, copies pinned love.nro → dist/switch/loose/ as gen1recomp.nro + game.love side by side. Needs the pin.
--fused	Builds dist/switch/gen1recomp-<ver>-switch.nro (game in romfs) via nacptool + elf2nro, then packs dist/switch/gen1recomp-<ver>-switch.zip (SD-ready tree). Needs the pin + toolchain (native or Docker). GitHub Releases publish the zip only.

Rules:

• --fetch alone is fine; combine as --fetch --loose or --fetch --fused.
• --loose and --fused are XOR — pick one packaging path per run.
• --version X.Y.Z sets the NACP / filename version (defaults to short git SHA).

What --fetch downloads

Only the two pinned love-nx release assets (love.nro, love.elf). It does not install:

• devkitPro / dkp-pacman / switch-dev
• Docker
• ROMs, saves, or mods

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Native tools, then Docker

Fused packaging (scripts/switch/build_fused.sh):

1. Prefer native nacptool + elf2nro on PATH (or $DEVKITPRO/tools/bin).
2. Else fall back to Docker using:
   • GEN1_DKP_IMAGE if set, otherwise
   • the image named in scripts/switch/dkp-docker.image (default devkitpro/devkita64:latest).

If neither native tools nor Docker work, the script exits non-zero with macOS / Linux / Windows / Docker hints and a pointer to this doc.

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Example commands

From the repo root:

# Download pinned love-nx only
scripts/build_switch.sh --fetch

# Loose pair for iteration (fetch + assemble)
scripts/build_switch.sh --fetch --loose

# Single fused NRO + SD-ready zip for a release-like artifact
scripts/build_switch.sh --fetch --fused --version 0.2.0

Outputs land under dist/switch/ (and dist/switch/loose/ for loose mode). The fused path also writes gen1recomp-<ver>-switch.nro.sha256 and gen1recomp-<ver>-switch.zip (+ .sha256 sidecar for the zip).

Offline packaging smoke (no network, no nacptool required):

bash scripts/switch/selftest_build_switch.sh
bash scripts/switch/verify_payload.sh --self-test

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CI and release

Switch packaging has three automated surfaces (same policy as AD-010):

Path-gated PR / push CI (.github/workflows/ci.yml)

When a change touches Switch packaging paths (scripts/build_switch.sh, scripts/switch/**, docs/switch-build.md, tests/switch_ci_workflows_test.lua, or the Switch-related workflow YAML), CI runs:

1. Offline selftest on ubuntu-latest (forks and the canonical repo): scripts/switch/selftest_build_switch.sh, scripts/switch/verify_payload.sh --self-test, and luajit tests/switch_ci_workflows_test.lua.
2. Fused NRO build only on the canonical repository (bryanthaboi/gen1recomp), on the self-hosted Mac runner (scripts/build_switch.sh --fetch --fused), and only when the workflow head is that repo (same-repo push/PR). Fork repository CI never runs fused. Fork → canonical PRs also skip Switch fused (offline selftest still runs) so untrusted head code is not executed on the self-hosted Mac; iOS device build eligibility is unchanged. Fused also waits for a successful offline selftest before starting on the Mac runner.
3. On successful PR fused builds, a follow-up workflow posts a PR comment linking the Actions artifact named gen1recomp-switch-nro (comment tag switch-build-result; see .github/workflows/switch-artifact-comment.yml).

Unrelated PRs do not burn the self-hosted Mac on Switch packaging.

Release hard-fail (.github/workflows/release.yml)

GitHub Releases always build Switch on the same self-hosted Mac runner as the other platforms — this is a hard gate (no continue-on-error):

scripts/build_switch.sh --fetch --fused --version "<release version>"

A Switch packaging failure fails the entire release job. The release asset is gen1recomp-<ver>-switch.zip (SD-ready); the versioned .nro stays under dist/switch/ for the packer and for PR CI artifacts.

Runner provisioning

The self-hosted Mac runner must have native switch-tools (nacptool / elf2nro) and/or Docker available. CI and release do not silently run dkp-pacman -S; keep the runner image/host provisioned per this guide.

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Limitations / non-goals

These scripts and this guide do not:

• Push files to the console (no automated MTP / FTP / SD scripting)
• Bundle or download any Pokémon ROM
• Install dkp-pacman / switch-dev for you
• Provide nxlink / netloader deploy (deferred — see switch-transfer.md)
• Validate Applet Mode — use title override (hold R) for full memory

Player install steps: switch-install.md.
Manual transfer (MTP / SD / FTP, macOS / Linux / Windows): switch-transfer.md.
Hardware depth and evidence: switch-development.md, switch-hardware-evidence.md.