KNULLI Quick Menu Not Opening? Fix M+B and RetroArch Hotkey Problems

Short Answer

On an RG CubeXX running KNULLI, the default built-in shortcut for RetroArch Quick Menu is:

Hold the physical Menu button. KNULLI calls this the Function button.
Keep it held.
Tap the physical B button at the south/bottom face position.
Release both buttons.

This is commonly called M+B or Menu+B. KNULLI’s documentation presents it as Function + south, not only as the literal text “M+B.”

If nothing opens, first confirm that the game is using a RetroArch/libretro core. Then test the built-in controls, check player-1 ownership, inspect only the scoped RetroArch Menu hotkey, and consider the documented Full-UI and N64 exceptions.

Stop when the visible RetroArch Quick Menu opens reliably. This guide does not continue into Core Options, controls remapping, save states, or emulator-specific configuration.

For adjacent problems, use the KNULLI on RG CubeXX troubleshooting and setup hub.

Exact Symptom and Scope

This guide applies when:

a game or content entry launches;
you expect the built-in RG CubeXX shortcut to open RetroArch Quick Menu;
holding Menu/Function and tapping B produces no visible Quick Menu, triggers another action, works only in some systems, or works only with one controller.

It covers these branches:

built-in RG CubeXX controls do nothing;
the shortcut works in one system or core but not another;
built-in controls work but an external controller does not;
another hotkey action triggers;
a per-game or per-system hotkey setting conflicts with the default;
a standalone emulator is active, so RetroArch Quick Menu is not applicable;
KNULLI is in a non-Full UI mode;
an N64 core uses N64 (Limited Hotkeys).

It does not cover DOSBox mouse or keyboard settings, Core Options persistence, save-state or Hardcore restrictions, games not appearing, BIOS, storage, networking, scraping, or broad controller-pairing repair.

First Test: Is This a RetroArch Session?

RetroArch Quick Menu exists for an active RetroArch/libretro core-and-content session. A standalone emulator can have its own menu, but that is not RetroArch Quick Menu.

Before changing anything:

Highlight the game in EmulationStation.
Hold the normal launch/confirm button.
Open Advanced Game Options.
Read the current Emulator value.

Continue only if it identifies a libretro/RetroArch core. Do not change the emulator merely to make M+B work.

If the game uses a standalone emulator, stop. Its shortcut and menu behavior are emulator-specific and outside this guide.

Release and Device Evidence

Evidence scope

Device: RG CubeXX built-in controls; H700 behavior only where shared tagged source supports it

KNULLI: Firefly 20241204, Gladiator II 20250813, Scarab 20260511

Default action: player-1 hotkey-enable + B → RetroArch menu_toggle

Evidence: Official documentation and tagged source; no owner hands-on test is claimed

End point: Quick Menu opens, closes, and reopens in one supported libretro session; after a correction, it also works after relaunch

All three tagged controller profiles identify the RG CubeXX built-in Menu control as the hotkey-enable input and its physical B button as the south action. Their RetroArch generators assign B to menu_toggle by default and take the hotkey-enable input from player 1.

Do not generalize the CubeXX’s M label, physical button IDs, or layout to every H700 handheld. The generated hotkey logic is shared, but physical controls are device-specific.

Default Built-In M+B Procedure

Use the built-in RG CubeXX controls before diagnosing an external controller.

Launch one legally owned game that you confirmed uses a libretro core.
Wait until gameplay is active.
Hold the physical Menu/Function button first.
While holding it, tap the physical B button at the south/bottom face position.
Release both buttons.

Do not invent a timed simultaneous press, one-second hold, long hold, or double-tap. KNULLI documents the sequence as holding Function and then pressing the action button.

Do not use Function+Start as a harmless test of the modifier. That shortcut exits the running application.

Success is visible: the screen identifies Quick Menu and shows content-related entries. A screenshot can show that the menu was visible, but it cannot prove which buttons opened it, which controller was player 1, why it previously failed, or whether the fix will persist.

Branch Matrix

Branch 1: A standalone emulator is active

Fact: RetroArch Quick Menu applies to RetroArch/libretro sessions.

Action: Stop this procedure. Do not call a standalone emulator’s overlay RetroArch Quick Menu, and do not switch emulators as a repair step.

Branch 2: Built-in controls work, but an external controller does not

Likely cause: The generated global hotkeys belong to player 1. Gameplay can work on another port even when that controller does not own the hotkey-enable action.

Safe order:

Exit the game before changing assignment.
Confirm that the built-in CubeXX M+B shortcut works.
Check controller assignment and which controller is player 1.
On current KNULLI, Gladiator II, and Scarab, inspect START → Controller & Bluetooth Settings → Use Handheld Controls for Player 1 if the option is present.
Relaunch before retesting.

Current KNULLI documentation says controllers are assigned in connection order and cannot be reassigned while in-game. The exact player-1 toggle path is not established for Firefly, so on Firefly use the built-in-versus-external comparison without claiming that exact toggle exists.

External controllers without a Function button often use Select as the hotkey substitute, but this is not guaranteed. Do not assume Xbox, PlayStation, or other face-button labels match the CubeXX, and do not begin a broad pairing or remapping procedure here.

Branch 3: It works in most systems but not one game or system

Likely cause: A per-game or per-system hotkey value differs, or that title is launching through a standalone emulator.

Recheck the affected game’s Emulator value. If it is libretro, inspect the narrowest KNULLI hotkey scope and record the current RetroArch Menu value before changing anything.

Branch 4: Another hotkey action triggers

Likely cause: A scoped hotkey customization or conflict moved the menu action.

Do not remap all controls. Record the current values, then restore only RetroArch Menu to B at the affected per-game or per-system scope.

Likely cause: Player assignment or that controller’s hotkey-enable mapping differs from the built-in profile.

Treat this separately from the built-in result. Do not infer a hardware fault, and do not assume Select is universally the correct modifier.

Branch 6: The frontend is in a non-Full UI mode

Fact: Firefly, Gladiator II, and Scarab generators remove menu_toggle when KNULLI’s UI mode is not Full. Gameplay buttons can still work while the normal Quick Menu shortcut is intentionally absent.

Use KNULLI’s supported interface-unlock flow to return to Full UI. Scarab’s pinned frontend source exposes UNLOCK USER INTERFACE MODE and an on-screen code prompt in restricted mode.

The exact historical prompt wording is not pinned for Firefly or Gladiator II. Follow the available on-screen KNULLI UI; do not edit settings files or reveal an unlock code in screenshots.

Branch 7: It fails only in Mupen64Plus-Next or ParaLLEl N64

Fact: For those libretro N64 cores, player-1 N64 (Limited Hotkeys) intentionally replaces the normal hotkey set with exit only. The menu toggle is absent.

Inspect Player 1 Controller Type. Record the current value before making a choice.

Keep N64 (Limited Hotkeys) if its restricted behavior is wanted.
Choose RetroPad (Default) or another non-limited type only if you accept that gameplay mapping can change.

Relaunch after a change. Do not present Limited Hotkeys as broken.

Branch 8: A `.rmp` remap exists

Fact: .rmp files remap gameplay/core input. KNULLI’s menu toggle is a separate frontend hotkey binding.

Do not delete .rmp files to repair M+B. Their presence alone does not prove they changed the global menu shortcut. Likewise, do not delete .cfg overrides or generated RetroArch configuration.

Safe UI Recovery in Narrow Order

Use only the branch that matches the symptom. Preserve every before-value.

1. Record the current context

Note:

KNULLI release;
game and system;
selected emulator/core;
whether an external controller is connected;
which controller is player 1, if known;
current UI mode, if visible;
current RetroArch Menu hotkey value.

Do not include usernames, network identifiers, full library paths, controller serials, or unlock codes in notes or screenshots.

For one affected game:

Highlight the game.
Hold the launch/confirm button.
Open Advanced Game Options.
Open Controls.
Open Hotkeys on Firefly, or RetroArch Hotkeys on Gladiator II and Scarab.
Find RetroArch Menu.
Record its current value.
If it is not B, change only this action to B.

For one affected system:

Open START → Game Settings → Per System Advanced Configuration.
Choose the system.
Open Controls.
Open Hotkeys on Firefly, or RetroArch Hotkeys on Gladiator II and Scarab.
Record RetroArch Menu, then set only that action to B if necessary.

The option description is Default hotkey + B. in all three tagged releases.

Use the narrowest affected scope. Current documentation and Gladiator II release material differ on global customization availability, so this guide does not use a global hotkey repair.

3. Apply only indicated exception fixes

If UI mode is restricted, use the supported KNULLI unlock interface and return to Full.
If failure is limited to the two named N64 cores, inspect the player-1 controller type and consider the mapping tradeoff.
If only an external controller fails, adjust player assignment outside the game before touching hotkey values.

4. Relaunch

Exit the game normally and launch the same entry again. KNULLI regenerates RetroArch input configuration at launch, so an already-running session does not prove that the new KNULLI-side value was applied.

Do not edit retroarch.cfg, copy controller profiles, use shell commands, delete configuration, reset controls globally, factory-reset, reflash, or update or downgrade KNULLI.

Deterministic Verification

Use the same legally owned game and the same confirmed libretro core throughout.

First-session check

Launch the game.
Hold Menu/Function, then tap physical B/south.
Confirm the visible header says Quick Menu and content-related entries are present.
Close or resume the content.
Repeat the same shortcut.
Confirm Quick Menu opens a second time.

Opening twice proves that the shortcut works in that active libretro session.

Persistence check after a KNULLI setting change

Exit the content normally.
Relaunch the same game and core once.
Hold Menu/Function, then tap B.
Confirm Quick Menu opens again.

Opening after relaunch supports persistence of the KNULLI-side correction. A single Quick Menu screenshot does not prove persistence or root cause.

Stop here. Do not enter Core Options or continue into DOSBox, save-state, input-remap, or emulator tuning tasks.

If It Still Fails

Do not keep changing unrelated settings. Record a concise escalation set:

device: RG CubeXX;
exact KNULLI release;
game/system and selected emulator/core;
built-in or external controller;
player-1 assignment;
Full or restricted UI mode;
N64 controller type, if relevant;
before and after RetroArch Menu value;
whether another hotkey action triggered;
whether the menu ever opened before or after relaunch.

Classify the unresolved result carefully:

Fact: a supported libretro game is running and the documented shortcut still does not open Quick Menu.
Likely: a remaining input, player-assignment, or scoped configuration conflict exists.
Unconfirmed: hardware failure. These checks do not establish it.

Do not delete configs or remaps, reset the device, reflash, copy files from another release, switch cores, or broaden the task into controller pairing.

Version Differences

Firefly `20241204`

Official RG CubeXX image and built-in controller profile
Built-in hotkey + B generates RetroArch menu_toggle
Hotkey submenu label: HOTKEYS
Option: RETROARCH MENU
Non-Full UI removes menu toggle
N64 (Limited Hotkeys) retains only exit

Gladiator II `20250813`

Official RG CubeXX image and same built-in physical mapping
Same player-1 menu-toggle default
Hotkey submenu label: RETROARCH HOTKEYS
Added global RetroArch hotkey customization and the built-in-player-1 toggle, but this guide uses safer per-game/per-system recovery
Same non-Full and N64-limited restrictions

Scarab `20260511`

H700/RG XX continuation with the RG CubeXX controller entry marked internal
Same built-in mapping and player-1 default
Hotkey submenu label: RETROARCH HOTKEYS
Pinned frontend exposes UNLOCK USER INTERFACE MODE in restricted mode
Same non-Full and N64-limited restrictions

English capitalization and theme presentation can vary. Do not generalize the RG CubeXX’s physical M/Menu label to every H700 device.

Non-Overlap Audit: All 10 Published Posts

This article is a PASS against every existing post because it stops when RetroArch Quick Menu opens.

PASS — DOSBox Pure mouse sensitivity: that guide starts after menu access and changes mouse options.
PASS — DOSBox Pure keyboard controls: that guide covers keyboard and mapping workflows after menu access.
PASS — DOSBox Pure settings not saving: that guide covers .opt and Core Options persistence.
PASS — KNULLI games not showing: discovery and game-list scope are excluded.
PASS — KNULLI missing BIOS warning: BIOS placement and checking are excluded.
PASS — KNULLI SMB share not visible: network file transfer is excluded.
PASS — KNULLI Wi-Fi problems: connectivity is excluded.
PASS — KNULLI scraped box art not showing: scraping, media, and theme refresh are excluded.
PASS — KNULLI second SD card detected but not used: storage selection and card remediation are excluded.
PASS — KNULLI save states and Hardcore Mode: that guide assumes menu access or direct shortcuts and diagnoses save/load restrictions; this guide ends before that diagnosis.

FAQ

Is M+B the official KNULLI name for the shortcut?

It is common RG CubeXX shorthand. KNULLI documents the modifier as Function, which may also be called F, M, Menu, or hotkey, and shows the action as the south face button. On the RG CubeXX, that physical south button is B.

Should I press M and B at exactly the same time?

KNULLI says to hold Function first and then press the action button. It does not document a timed simultaneous press, long hold, or double-tap.

Why does M+B work on the built-in controls but not my external controller?

Generated global hotkeys belong to player 1. The external controller may be assigned to another player or use a different hotkey-enable input. Select often substitutes for Function on external pads, but not universally.

Why does it fail only in N64?

For Mupen64Plus-Next and ParaLLEl N64, N64 (Limited Hotkeys) intentionally removes menu access and retains exit only. Changing controller type can also change gameplay mapping, so record the original setting and choose deliberately.

Should I delete an `.rmp` remap?

No. .rmp files are the gameplay/core remap layer. The generated RetroArch menu toggle is a separate frontend hotkey binding.

Why did a direct RetroArch hotkey edit revert?

KNULLI regenerates emulator configuration at launch. Use KNULLI’s per-game or per-system Hotkeys UI instead of editing generated RetroArch configuration.

It proves that Quick Menu was visible in that session. It does not prove which buttons opened it, which controller owned the hotkey, the previous cause, or persistence. Reopen it once, and after a KNULLI-side change, relaunch and repeat.