The libretro folder

Alongside your games sits a second tree, libretro/. RetroXR owns this one: the core downloader fills it in, and you rarely need to open it.

It is worth knowing what is in it, because it is where a stubborn BIOS problem or a corrupted core option actually lives.

Where it is

Platform	Location
Windows	%USERPROFILE%\retroxr\libretro
Linux / macOS	~/retroxr/libretro
Quest	internal app storage — reachable as libretro/ in the web file manager

On Quest this folder is not next to your games. Your games live in external storage where you can copy files freely; libretro/ is in the app’s own private storage. The web file manager shows both under one root, which is the only place you will see them side by side.

What is in it

libretro/
  cores/                 the emulator cores themselves
  system/                BIOS and firmware, one folder per core
  core_assets/           asset packs some cores need
  core_options/          your per-core settings
  save/                  battery saves
  temp/                  scratch space
  cores_manifest.json    what is downloadable, and what you have
  core_defaults.json     which core each system launches with
  firmware_state.json    which BIOS files are present

cores

One file per emulator. These arrive through CORES → Download and there is no reason to put them here by hand — a core dropped in manually will not be registered in the manifest.

system

This is the one you may legitimately need to open. Cores look for their BIOS and firmware here, in a folder named after the core. The PlayStation’s scph5500.bin and friends, the Dreamcast’s boot ROM, the DS firmware — all of it lands under system/.

The BIOS page is the friendlier route: it tells you which files a system wants, by exact name, and where they go.

core_options

Your settings for each core, written when you change something in CORES → Manager. If a core is behaving strangely and you want a clean slate, resetting its options from the Manager rewrites the file for you — safer than editing it.

save

Two different things, filed two different ways:

save/<core>/<game>/<save>.srm      cartridge battery saves — per core, per game
save/memcards/<systemid>/<name>.mcr  memory cards — per console family, no core

A cartridge kept its save on its own chip, so the path is keyed by the game. A memory card is one image that every game on that console writes into — which is the entire point of a card — so it is keyed by the card instead.

The card path carries no core name on purpose: the raw image is identical for every PlayStation core, so a card survives switching cores the way a real one survives switching consoles. Cartridge saves do not. See the PlayStation and game saves and backups.

temp

Scratch space. RetroXR copies a core here before running it, so one machine’s core cannot tread on another’s. Nothing in here is worth keeping.

On Quest, use the web file manager — not adb or SideQuest

libretro/ is in the app’s internal storage, not on /sdcard with your games. Two consequences:

• adb push and SideQuest’s file browser cannot reach it, so there is nothing to find there. Don’t go looking.
• The web file manager can, and it is safe: it is the app’s own server, so anything uploaded through it is owned by the app and stays writable. This is the supported way to put a BIOS file in place.

The rule being protected is about ownership, not the folder: a file forced in from a PC by other means lands owned by the shell, and RetroXR can no longer write to it. A config it cannot update looks exactly like a config that was wiped. If something needs replacing, delete it and let RetroXR fetch it again.

When a core misbehaves

In rough order of what to try:

1. Reset the core’s options in CORES → Manager. Most odd behavior is a setting.
2. Check its BIOS in CORES → BIOS / Extras. A missing required file usually shows as a machine that powers on and does nothing.
3. Re-download the core. It replaces the file in cores/.
4. Try a different core for that system, if one exists.