Set Up Multi-Disc Games in KNULLI with an M3U Playlist

Owner testing: NO — this is a documentation-led procedure. Retro Fix Lab did not reproduce it on owner hardware.

This guide covers one narrow job on an RG CubeXX/H700 KNULLI installation: add one plain-text M3U playlist around an existing, legal, independently known-good multi-disc set, then check frontend grouping and perform one reader-side Disc 1 launch. It does not cover downloads, repairs, conversion, BIOS setup, emulator changes, disc swapping, saves, states, or performance tuning.

The evidence gate for this article passed. That is an editorial evidence decision, not a claim that Retro Fix Lab tested the workflow. The frontend and file workflow is source-confirmed for Firefly 20241204, Gladiator II 20250813, Scarab 20260511, and current KNULLI while the current official documentation still matches. Emulator/core and disc-format support must be proved separately for the exact target.

Short answer

If every eligibility check below passes, create one game-named plain-text .m3u in the active KNULLI system folder. Put one exact relative disc reference on each line, in order, without moving the original files. Make sure KNULLI’s multi-file-disc hiding option is on, run Update Gamelists, verify grouping, and then perform one compatibility-gated launch through the playlist to confirm only that Disc 1 opens.

Do not start with file creation. If any release, storage, path, filename, core, format, or content-health detail is uncertain, stop first.

Version and device support is not core compatibility

Installed target	Frontend/file workflow status	What this does not prove
RG CubeXX/H700, Firefly `20241204`	Source-confirmed from release-pinned KNULLI documentation	Support in every system, core, standalone emulator, or format
RG CubeXX/H700, Gladiator II `20250813`	Source-confirmed from release-pinned KNULLI documentation	Universal launch compatibility
RG CubeXX/H700, Scarab `20260511`	Source-confirmed from release-day KNULLI documentation	Universal launch compatibility
RG CubeXX/H700, current KNULLI	In scope only while current official documentation still matches the path, setting label, and refresh workflow in this guide	Compatibility with future builds or changed documentation

This matrix establishes the KNULLI frontend/file workflow only. Before creating a playlist, official documentation applicable to the exact selected core/system must confirm both M3U support and the target disc format. For a standalone emulator, use that standalone’s own exact-version documentation; generic Libretro guidance is not enough.

If current KNULLI documentation no longer matches this guide, stop and return the procedure for research rather than adapting it by guesswork.

Eligibility gate: every item must pass

Proceed only when all of these statements are true:

You have a legally obtained multi-disc set that you are entitled to use.
You know the installed KNULLI release: Firefly 20241204, Gladiator II 20250813, Scarab 20260511, or a current build whose official workflow still matches this guide.
You know which userdata is active: SD1 SHARE in a single-card setup, or the selected SD2 main partition in a configured dual-card setup.
You know the exact existing KNULLI-scanned system folder: /userdata/roms/<system>/, shown from the SHARE root as roms/<system>/.
The original set is independently known-good, or every disc has separately passed the appropriate content, BIOS, and emulator checks. This guide’s later Disc 1 launch does not validate every disc.
Official documentation applicable to the exact selected core/system confirms both M3U and the referenced disc format. For a standalone emulator, its own exact-version documentation confirms both.
You know every filename, capitalization, extension, and relative location exactly.
Every original disc file will remain in place. This procedure adds one playlist; it does not move, rename, convert, modify, or delete originals.
You have privately recorded the actual current value of Ignore Multi-File Disk Content (CUE/GDI/CCD/M3U).
You have a plain-text editor and can see file extensions well enough to verify .m3u, not .m3u.txt.

STOP before changing files if

the release, active userdata, exact system folder, selected emulator/core, filename case, extension, or relative path is unknown or ambiguous;
the files sit outside the active /userdata/roms/<system>/ tree or on inactive userdata;
exact applicable official documentation does not confirm both M3U and the referenced format;
a standalone target is supported only by generic Libretro documentation;
any disc is missing, corrupt, independently unverified, or already fails;
the task would require moving, renaming, converting, deleting, downloading, repairing, formatting, acquiring content, doing BIOS work, or changing the emulator/core;
plain text or the exact .m3u extension cannot be guaranteed;
the intended playlist requires syntax excluded later in this guide;
current official KNULLI documentation conflicts with the path, setting label, or refresh flow below; or
the proposed result would be treated as proof of disc swapping, Disc Index behavior, saves/states, every-disc validity, universal support, performance, or region/revision behavior.

Confirm the active storage and system folder

KNULLI uses one active userdata store. The in-system path for a scanned system folder is:

/userdata/roms/<system>/

From the SHARE root, the same folder appears as:

roms/<system>/

<system> is a placeholder, not a folder name to copy blindly. Use the exact existing system folder KNULLI already scans. Do not treat a generic /roms path as separate storage.

In a single-card setup, active userdata is on SD1 SHARE. In a configured dual-card setup, it is on the selected SD2 main partition. A correctly written playlist on inactive storage proves nothing. If TF1/TF2 roles or the active userdata location are unclear, stop and use the KNULLI card roles and filesystem guide; do not format, repair, or choose storage as part of this procedure.

Treat system folders, filenames, extensions, and playlist references as case-sensitive. Record the exact current path and name of every original before continuing.

If you first need an established legal file-access or copy route, use the KNULLI SMB/SFTP transfer guide. This article does not repeat network setup.

Choose an existing additive layout

Use the layout your files already have. Do not move or rename files to imitate an example, and do not introduce deeper nesting. The fictional title Star Harbor keeps private library details out of the examples.

Layout A: playlist beside top-level discs (preferred)

/userdata/roms/<system>/
├── Star Harbor (Disc 1).chd
├── Star Harbor (Disc 2).chd
└── Star Harbor.m3u

Star Harbor.m3u contains:

Star Harbor (Disc 1).chd
Star Harbor (Disc 2).chd

Layout B: playlist and discs in one existing game subfolder

/userdata/roms/<system>/Star Harbor/
├── Star Harbor (Disc 1).chd
├── Star Harbor (Disc 2).chd
└── Star Harbor.m3u

The playlist still uses filename-only lines:

Star Harbor (Disc 1).chd
Star Harbor (Disc 2).chd

Layout C: top-level playlist pointing into one existing subfolder

/userdata/roms/<system>/
├── Star Harbor.m3u
└── Star Harbor/
    ├── Star Harbor (Disc 1).chd
    └── Star Harbor (Disc 2).chd

Star Harbor.m3u contains:

Star Harbor/Star Harbor (Disc 1).chd
Star Harbor/Star Harbor (Disc 2).chd

KNULLI documentation may use hidden as an example folder name. It is only an ordinary name—not a required folder, reserved word, filesystem attribute, or compatibility feature. Do not create it, mark files hidden, or move files into it for this guide.

M3U syntax: keep it deliberately narrow

For this procedure, the playlist must be:

one plain-text file with the exact .m3u extension;
one exact relative target per line;
ordered by disc, with Disc 1 first;
filename-only when the playlist and discs share a folder; or
Subfolder/Filename when a top-level playlist points to files in one existing subfolder.

Every letter, space, parenthesis, extension, and capitalization must match the real file.

Do not use comments, #EXTM3U, absolute paths, quotes, encoding/BOM instructions, backslashes, ../, blank lines, URLs, escaping, tabs, trailing-space behavior, wildcards, environment variables, or deeper nesting. Those forms are outside the evidence for this article.

Pass the exact core and format gate

The frontend setting named later includes several extensions, but its label describes hiding behavior. It is not a launch-compatibility list and does not prove that a core accepts any listed format.

Proposed target	Decision before playlist creation
CHD	Conditional: exact official documentation for the selected core/system must confirm both M3U and CHD. CHD is not universally supported.
BIN/CUE	Conditional: exact official target documentation must confirm both M3U and CUE. Put only each `.cue` in the M3U; keep all paired BIN files in place.
Direct `.bin` line	Forbidden. Stop.
ISO	Excluded by default. Proceed only if exact official target documentation expressly confirms M3U plus ISO.
GDI	Excluded by default. Proceed only if exact official target documentation expressly confirms M3U plus GDI.
CCD	Excluded by default. Proceed only if exact official target documentation expressly confirms M3U plus CCD.
Any other extension	Stop; this evidence package does not approve it.
Standalone emulator	Conditional only when that standalone’s own exact-version documentation confirms M3U and the target format.
Unknown core/emulator	Stop.

For a BIN/CUE set, a two-disc playlist would therefore name the CUE files—not the BIN files:

Star Harbor (Disc 1).cue
Star Harbor (Disc 2).cue

The paired BIN file or files remain untouched beside their CUE files.

Preserve the before-state

Before creating anything, privately record:

the installed KNULLI release;
the active userdata location;
the exact existing system folder;
the selected core/system or exact standalone version;
the documentation that confirms M3U plus the exact target format;
every disc’s current exact path, filename, capitalization, and extension; and
the current on/off value of Ignore Multi-File Disk Content (CUE/GDI/CCD/M3U).

Official KNULLI documentation describes that setting as on by default, but do not assume. The actual value on your device controls rollback.

A separate broader backup is optional context for this one-file additive procedure. The M3U is not a backup, and preserving every original is mandatory. If you want broader preservation guidance, see Back Up KNULLI Saves and Personal Data.

Create the M3U

Confirm that every eligibility and format/core condition above passes.
Match one of the three approved layouts to the files as they already exist.
In a plain-text editor, create exactly one game-named file—for example, Star Harbor.m3u.
Verify that the saved filename ends in .m3u, not .m3u.txt.
Add one exact relative disc target per line in disc order, with Disc 1 first.
Use filename-only lines when the M3U and disc targets share a folder. Use Subfolder/Filename only for the documented top-level-playlist-to-one-existing-subfolder layout.
Reopen the saved M3U and compare every line character-for-character with the actual filename and relative location, including capitalization and extension.

Do not rearrange the originals during this process.

Hide individual disc entries and refresh KNULLI

On the device, open:

Start → System Settings → Frontend Developer Options → Ignore Multi-File Disk Content (CUE/GDI/CCD/M3U)

Ensure the setting is on. It changes frontend visibility only; it does not delete, move, rename, convert, or modify disc files.

Then run:

Main Menu → Game Settings → Update Gamelists

Do not substitute a reboot or an unrelated scan procedure for this documented refresh step.

Stage 1: verify frontend grouping

After Update Gamelists, all three checks must pass:

Exactly one playlist-named entry is visible for the test set.
Every correctly referenced individual disc entry for that M3U is absent from the frontend list.
Every original disc file remains unchanged at its recorded path.

This proves only that KNULLI recognized and grouped the referenced files for this M3U and this scan. It does not prove launch compatibility.

If the playlist entry itself is absent after correct placement and refresh, stop and use Games Not Showing Up in KNULLI.

If individual disc entries remain visible, that is only likely to indicate an M3U issue. Recheck the exact references, capitalization, relative path, hide setting, completed gamelist update, installed release, and documented scope. If the locked inputs do not reveal the problem, stop. Do not infer a universal root cause or expand into broad troubleshooting.

Stage 2: perform one reader-side Disc 1 launch

Run this stage only after official documentation applicable to the exact selected core/system—or the exact standalone version—has confirmed both M3U and the target format.

Select the playlist entry only.
Start one controlled launch.
Pass only if the expected Disc 1 title/menu, or another unambiguous Disc 1 start state, remains responsive long enough to establish that Disc 1 loaded.
Exit normally.

Do not advance to a disc-change prompt, alter Disc Index, test tray/eject/swap behavior, create or overwrite a save, load or create a state, switch the emulator/core, test another disc, or tune performance.

If the visible playlist entry returns to the menu or otherwise fails during this bounded launch, stop and use the visible game launch failure handoff. If the launch shows an explicit missing-BIOS warning, use the KNULLI missing BIOS warning guide. If exact compatibility research shows that the selected emulator/core is wrong, use the per-game emulator/core selection guide; this article does not reproduce its selector steps or recommend a replacement.

What the checks prove—and what they do not

A grouping pass shows that KNULLI recognized this playlist and grouped its correctly referenced files for this scan.

A reader-side launch pass shows only that this exact M3U, exact files, exact selected core/system or standalone version, and installed build opened Disc 1 in that controlled session. Retro Fix Lab did not perform that launch on owner hardware.

Neither check proves:

cross-disc handoff or Disc Index behavior;
tray, eject, or swapping behavior;
save sharing, save compatibility, migration, or save-state compatibility;
that every disc is valid;
universal support across formats, systems, cores, standalone emulators, releases, or devices;
performance, battery behavior, thermals, latency, or long-session stability;
region or revision equivalence; or
a root cause when grouping or launch fails.

The original set’s known-good status is an eligibility requirement established before this workflow, not a result of the one Disc 1 launch.

Roll back the change

Exit any running game normally.
Remove only the newly created .m3u from its exact active /userdata/roms/<system>/ location or existing game subfolder.
If this procedure changed Ignore Multi-File Disk Content (CUE/GDI/CCD/M3U), restore its recorded prior value. If it was already on, leave it on.
Run Main Menu → Game Settings → Update Gamelists.
Confirm that the original individual disc entries return, subject to normal scanning and unrelated existing frontend rules.
Confirm that every original disc file remains untouched at its original path.

Rollback must not delete, move, rename, convert, repair, or replace original disc files. If files were moved before this procedure, removing the M3U cannot reconstruct their old layout; that situation is outside scope.

Bounded handoffs

Use these only when the named condition is reached:

For optional KNULLI/RG CubeXX navigation, visit the KNULLI on RG CubeXX setup and troubleshooting hub.
If the M3U entry itself is absent after correct placement and refresh, use Games Not Showing Up.
If a visible playlist entry fails the single bounded launch, use the visible launch failure handoff.
If an explicit missing-BIOS warning appears, use the missing BIOS warning guide.
If exact evidence shows the selected emulator/core is wrong, use the per-game emulator/core guide.
If legal file access or transfer is needed, use the SMB/SFTP transfer guide.
If active TF1/TF2 userdata is unclear, use the card roles and filesystem guide.
For optional broader preservation context, use the backup guide. An M3U is not a backup.

This guide intentionally does not duplicate neighboring procedures for scanning failures, BIOS, emulator selection, transfer, storage, backup, controls, Quick Menu/Disc Index, saves/states, networking, scraping, installation, power, controllers, or Quick Resume.

FAQ

Does the playlist replace my disc files?

No. It is one added plain-text index. All original disc files stay in their existing locations unchanged.

Can I put BIN files directly in the M3U?

No. For an eligible BIN/CUE set, each playlist line names the exact .cue; the paired BIN file or files remain in place.

Are CHD files always safe to use in an M3U?

No. CHD is conditional. Exact official documentation applicable to the selected core/system must confirm both M3U and CHD.

Does the KNULLI setting label prove CUE, GDI, CCD, and M3U launch support?

No. Ignore Multi-File Disk Content (CUE/GDI/CCD/M3U) controls frontend visibility. It is not a compatibility list.

May I use ISO, GDI, or CCD files?

They are excluded by default in this guide. Use one only when exact official documentation for the selected target expressly confirms both M3U and that exact format.

Must I create a folder named `hidden`?

No. hidden is only an ordinary example name in KNULLI documentation. It has no special attribute or compatibility function.

Does a successful Disc 1 launch prove disc swapping works?

No. It proves only that the reader’s exact playlist, files, selected target, and installed build opened Disc 1 in that controlled session. Disc swapping and every later disc are outside scope.

Do I need a backup first?

A separate broader backup is optional for this additive one-file procedure, but preserving all original files is mandatory. The M3U itself is not a backup.

What if current KNULLI documentation differs from this guide?

Stop. A current build is covered only while the official path, setting label, and refresh workflow still match. Documentation drift requires a new research check.

Can screenshots prove owner testing?

No. Screenshots are optional and do not establish owner reproduction. Any editorial image should use fictional or fully redacted data—such as Star Harbor—and must not expose real library titles, ROM paths, usernames, hostnames, network identifiers, credentials, drive labels, save data, account identities, cloud details, unrelated files, or unlicensed game imagery.

Evidence labels

FACT: The cited releases provide official RG CubeXX/H700 image assets; this guide adds one M3U and preserves originals.
SOURCE-CONFIRMED: Current and release-pinned KNULLI documentation supports the active-userdata path, relative M3U workflow, plain-text playlist, disc order, exact frontend setting, default-on description, and gamelist refresh described here.
COMMUNITY REPORT: None is relied upon.
UNCONFIRMED / excluded here: undocumented playlist syntax; universal format, core, standalone, release, or device support; swapping; saves/states; every-disc validity; performance; and region/revision behavior.

Sources

Current KNULLI documentation

Release-pinned KNULLI documentation and releases

Firefly 20241204: pinned Multi-Disc Games, pinned Game Storage, documentation commit, official release
Gladiator II 20250813: pinned Multi-Disc Games, pinned Game Storage, documentation commit, official release
Scarab 20260511: release-day Multi-Disc Games, release-day Game Storage, documentation commit, official release

Libretro reference material

These sources do not establish owner reproduction, universal target support, cross-disc handoff, save/state behavior, or performance.