How to Build MW3DS from Linux

[floowsnaake-new]

MW3DS on a New Nintendo 3DS

How to build the Morrowind port on Debian-based Linux, package it as a CIA, and install it with GodMode9. This is the exact route that worked.

Tested on Debian Linux. Updated October 14, 2026.

What you need

• A New Nintendo 3DS or New 2DS XL with custom firmware (GodMode9 installed) and an SD card with about 3 GB free.
• A PC running Debian Linux. This guide was tested on Debian.
• Your own copy of Morrowind. The GOG version under Wine works, and you can buy it here: The Elder Scrolls III: Morrowind GOTY Edition on GOG. The project ships no game data, so this is required.
• Time. The data conversion step alone can take 30 to 60 minutes or more.

Part 1. Set up the PC

Install the base tools and devkitPro

sudo apt update
sudo apt install -y git python3 python3-pip python3-venv build-essential

wget -U "dkp-apt" https://apt.devkitpro.org/install-devkitpro-pacman
chmod +x install-devkitpro-pacman
sudo ./install-devkitpro-pacman

sudo dkp-pacman -S 3ds-dev 3ds-zlib

When pacman lists the 20 members of 3ds-dev, press Enter to install all of them.

Set the environment variables

Add these three lines to ~/.bashrc so they stick, then open a new terminal.

export DEVKITPRO=/opt/devkitpro
export DEVKITARM=$DEVKITPRO/devkitARM
export PATH=$DEVKITPRO/tools/bin:$DEVKITARM/bin:$PATH

Check it with arm-none-eabi-gcc --version. If the command is not found, $DEVKITARM/bin is missing from your PATH.

Get makerom

Download the Linux build of makerom from the Project_CTR releases, then run chmod +x makerom. This guide calls it by full path, so you do not have to add it to PATH.

Part 2. Build the game

Clone the project

git clone -b old-3ds --recurse-submodules https://github.com/3ds-conspiracy/mw3ds.git
cd mw3ds
python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

Convert the Morrowind data

Point MW3DS_MORROWIND_DIR at the Morrowind install root, the folder that contains Data Files, not at Data Files itself. Quote the path if it has spaces.

export MW3DS_MORROWIND_DIR="/home/YOU/.wine/drive_c/GOG Games/Morrowind"
ls "$MW3DS_MORROWIND_DIR/Data Files/Morrowind.esm"    # must print the file

python tools/convert/level.py --world

The converter is finished when the final game.json ... total line appears and your prompt returns. Output lands in out/data. Lines saying "vertices without bone weights" are harmless.

Compile the engine

make -j$(nproc)

You should end up with mw3ds.elf, mw3ds.3dsx and mw3ds.smdh in the project folder.

Package the CIA

The -ignoresign flag is what made the CIA installable here. Replace the makerom path with wherever you put it.

mkdir -p build/romfs
rm -rf build/romfs/data
cp -a out/data build/romfs/data

~/Downloads/makerom-v0.19.0-ubuntu_x86_64/makerom -f cia -o build/mw3ds.cia \
 -elf mw3ds.elf -rsf tools/build/mw3ds.rsf -icon mw3ds.smdh \
 -banner tools/build/banner.bnr -exefslogo -target t -ignoresign \
 -DAPP_TITLE=MW3DS -DAPP_PRODUCT_CODE=CTR-P-MW3D -DAPP_UNIQUE_ID=0xF3D50 \
 -DAPP_ROMFS=build/romfs -DAPP_CATEGORY=Application -DAPP_USE_ON_SD=true \
 -DAPP_ENCRYPTED=false -DAPP_MEMORY_TYPE=Application \
 -DAPP_SYSTEM_MODE=64MB -DAPP_SYSTEM_MODE_EXT=124MB \
 -DAPP_CPU_SPEED=804MHz -DAPP_ENABLE_L2_CACHE=true -DAPP_VERSION_MAJOR=0

rm -rf build/romfs/data      # optional, frees disk space

The result is build/mw3ds.cia, about 1 GB.

Part 3. Install on the console

1. Copy build/mw3ds.cia to your SD card. The root or any folder works.
2. Put the SD card in the console. Hold Start and power on to enter GodMode9.
3. Browse to the SD card and highlight mw3ds.cia, then press A.
4. Choose CIA image options, then Install game image, and confirm.
5. Wait for it to finish (about 1 GB), then reboot. MW3DS appears on the HOME menu.

Saves and settings go to sdmc:/3ds/mw3ds/ on the SD card.

Controls

In-game bindings are not listed here. I could not find a published controls list for MW3DS, and I did not want to guess. Check the project's README or the in-game options menu for the real mapping, and if you send it to me I will fill in a table here.

Troubleshooting

What you see	Cause	Fix
FileNotFoundError ... Data Files/Data Files/Morrowind.esm	Path points one folder too deep	Set MW3DS_MORROWIND_DIR to the install root, in quotes
Please set DEVKITARM	devkitPro variables not exported	Export the three variables, or add them to ~/.bashrc
arm-none-eabi-gcc: command not found	$DEVKITARM/bin missing from PATH	Add it to PATH
zlib.h: No such file	3DS zlib not installed	sudo dkp-pacman -S 3ds-zlib (or 3ds-portlibs)
makerom: command not found	Not on PATH	Call it by full path
cp: cannot stat 'out/data'	Wrong folder, or conversion not finished	cd into the project folder and re-run the converter
FBI rejects the CIA with a signature error	CIA is unsigned homebrew	Rebuild with -ignoresign and install with GodMode9

Credits

• Morrowind by Bethesda Game Studios. You must own a copy (buy it on GOG); none is distributed with this project.
• MW3DS by the 3ds-conspiracy project, which also states it does not distribute game data or prebuilt CIAs.
• devkitPro for the 3DS toolchain, Project_CTR for makerom, and the GodMode9 developers for the installer.

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[3ds-conspiracy]

Thanks, I think if I just use python as default instead of shell scripts in my main that should do the trick as well. Thanks for the guide between now and then