Hyperkins’ Retron5 – continuing licensing problems

Yesterday, Hyperkin responded to our earlier article by acknowledging that they indeed did do what we claimed them of having done. In response, they posted a raw source code dump of the video game emulator software in question, confirming they were indeed infringing copyright and violating licenses.



However, they did not open source the code taken from the RetroArch project that is used within Hyperkin’s own frontend software.

By using RetroArch’s GPLv3 code, they are not only violating the license but breaking clauses that prohibit “Tivoization”

Today, Hyperkin posted another statement regarding the allegations of RetroArch code, admitting that code is indeed used in their product shipped in all versions of their firmware below the most recent release.


I’d like to clarify one point regarding the allegations over at libretro.com: we are not using any of RetroArch in our “frontend” (libretron.so). While it is true that a few ASM functions from RetroArch were previously found in our frontend library, these were merely remnants of old test code which we unfortunately forgot to remove. The offending code has been removed as of the v2.0 update. We’re sorry that this code was left in the binary up until recently; it was merely an oversight on our part. Furthermore as you will see from the source release of the emulator cores, we have our own interface between the frontend and the core plugins, totally different from that used by RetroArch itself.

As our frontend does not include any code from the RetroArch frontend then it does not fall under GPLv3 as they claim, and thus is not bound by any of the anti “TIVO-ization” stuff.

We believe that previously distributed copies of Hyperkin’s firmware now fall under GPLv3 licensing and anti-tivoization terms and must be open sourced in order to adhere to the license. Also, we do not know the legality of selling a product with a firmware containing GPLv3 code in a TIVOized state, and then removing that GPLv3 code later on in a successive firmware update to effectively TIVO-ize it. That is something for FSF lawyers to ponder.

Visual evidence of RetroArch’s code in use by Hyperkin’s frontend binaries can be found here:
http://www.libretro.com/index.php/retroarch-license-violations/ (see middle section titled “RetroArch”)

This can be compared against this codebase snapshot (they based the code’s inclusion on this snapshot of the code) –


They’ve also alluded to using forced firmware updates to make sure the user cannot run original copies of the GPL software they bundle on this device, further adding to the TIVoization claims –


Q: Assuming someone does break into it, how are you going to deal with that?
A: We do provide firmware updates through SD card support. If we start noticing people hacking and things like that—which I’m not against whatsoever; that’s the times we live in now, where if you could hack something, you’re a genius—we can release firmwares at any moment that would be required to start playing games. With that, you know, we can limit the control on that. – See more at: http://www.gamnesia.com/articles/gam…5#.VCKBh-IvBhE

There is another problem with what was stated here –


They claim they no longer have any RetroArch code in their latest firmware and that  they have their own API that they use to dynamically link the core against their frontend (unreleased and closed-source). The problem with this is that their API appears to be not GPL-compatible.

For evidence, download the ZIP contained in here  (RetronN5Source-20140923.zip) and look at engine/retronCommon.h.


This API would need to be under a GPL-compatible license to be compatible with FCEU and VBA. Furthermore, it’s unknown what license the ‘frontend’ is licensed under, and since it’s closed-source and kept concealed, there’s no way of knowing if it infringes on the GPL license or not.

A core being exposed to the frontend through an API like this constitutes a combined work, because it is not a ‘well-separated work’ as per the terms stated here –


The core doesn’t do anything without the frontend, and the frontend links to this core dynamically through dynamic linking. The core is reliant on the frontend to do the audio/video/input processing, without which nothing would be displayed on the screen, no input would be received by the core, and no audio samples would get output.

Therefore, we believe that their latest acknowledgements raises even more questions as to the level of compliance they’ve demonstrated so far with the GPL license. It raises therefore even more questions than it solves, further adding to the already quite considerable list of problems with this device.

Non-commercial cores – SNES9x Next

And of course, the fact that the two non-commercial cores are still being shipped with the device is another problem altogether. The license for SNES9x states specifically:


Permission to use, copy, modify and/or distribute Snes9x in both binary
and source form, for non-commercial purposes, is hereby granted without
fee, providing that this license information and copyright notice appear
with all copies and any derived work.
This software is provided ‘as-is’, without any express or implied
warranty. In no event shall the authors be held liable for any damages
arising from the use of this software or it’s derivatives.
Snes9x is freeware for PERSONAL USE only. Commercial users should
seek permission of the copyright holders first. Commercial use includes,
but is not limited to, charging money for Snes9x or software derived from
Snes9x, including Snes9x or derivatives in commercial game bundles, and/or
using Snes9x as a promotion for your commercial product.
The copyright holders request that bug fixes and improvements to the code
should be forwarded to them so everyone can benefit from the modifications
in future versions.
Super NES and Super Nintendo Entertainment System are trademarks of
Nintendo Co., Limited and its subsidiary companies.


“Commercial users should seek permission of the copyright holders first” – refer to Hyperkin’s Retron5 licensing software page here –


They used the SNES9x Next fork specifically. This is a fork that I created specifically to serve as a libretro core. My list of contributions extends to the following:

– Added game-specific speedhacks to make them fullspeed for low-power systems like the Nintendo Wii and PlayStation3. This includes games like Final Fantasy III/VI, Star Fox, Star Fox 2, Super Mario World 2: Yoshi’s Island, and numerous other cores which were previously too slow on such devices.

– Added SuperFX overclocking code to make it possible to run SuperFX games at faster rates.

– Converted the entire codebase from C++ to C89.

– Wrote the libretro API integration parts together with Themaister/Hans-Kristian Arntzen. (NOTE: Libretro is licensed under the MIT license)

As you can guess, they have never sought my permission to use this in their commercial product. And they will never get it either. They are expressly forbidden by me (one of the copyright holders) to use this version of SNES9x in their commercial product. I’m still awaiting a response from the rest of the upstream SNES9x devs but I can’t expect their reaction will be that much different.

I will be taking steps of my own accord to ensure that this situation will be rectified.

Non-commercial cores – Genesis Plus GX

The Genesis Plus GX developers have been made aware of the facts as well and they can make their own moves as to how to deal with this.

On SNES9x Next however, I have considerable copyright claims and therefore I am in an ideal position to clamp down on this misuse of its code.

Last parting message

This can be read from Hyperkins’ response to our earlier article on Nintendolife.com

It has always been our intention to release the relevant source code for the open source emulators used within RetroN 5. We have not been as quick as we could have been, since we have been busy improving the RetroN 5 user experience. The relevant source code has now been released. From this point forward we will not only keep our copy of this code updated for those who wish to obtain the latest version, but also submit patches for any fixes that we implement back to the original projects so that the entire community may benefit. Hyperkin will continue to endeavor to fulfill the licenses of any project used within RetroN 5 and any other software we write.

If Hyperkin is indeed serious about this, they will save my time and the time of the Genesis Plus GX developers by pre-emptively (and immediately) stripping the non-commercially licensed SNES and Genesis cores from their product. We’d rather be busy doing actual development that users benefit from and that benefits the community instead of having to go to the trouble of sending a bunch of Cease & Desist notices.

Also, let it be known that as of this moment I have contacted the FSF regarding the GPL violation matters because there remains too many unanswered and unsolved problems for us to be thoroughly satisfied. Our beef is not with the product – if Hyperkins’ Retron5 was put out in a honest way and in a way that wouldn’t infringe upon the licenses of these emulators, they would be legally allowed to use it in this way. As it stands, they did not do their homework before putting this product out and their actions so far reek of negligence, irresponsibility and a calculated move to reap the rewards of copyleft code without having to honor the license’s terms.

RetroArch, Libretro core license violations by Hyperkin’s Retron5

We have an open-source project called RetroArch. It has a development interface called libretro that allows for the easy creation of emulators and games that can plug straight into this program called RetroArch. This development interface is open to others so that they can run these pluggable emulator and game cores also in their own programs or devices. You can find this project on Github. (github.com/libretro). We also have a website – http://www.libretro.com. We started this project in late 2010 and we have been steadily increasing in popularity. We are on over 15 different hardware platforms right now that you can run RetroArch on, including Android (which this Retron5 device is based on).

These open-source programs are covered under certain licenses. Several of the emulators are covered under non-commercial licenses, which means they cannot be sold or profited from.

We have discovered that Retron5 is in violation of the licenses of several projects:

Genesis Plus GX
1. It uses the open-source emulator ‘Genesis Plus GX’ by author Eke-Eke for its Sega Genesis/Mega Drive module (https://github.com/ekeeke/Genesis-Plus-GX). This core has been licensed under a non-commercial license. It can therefore not be sold as, or part of, a commercial product.

Proof is in the accompanied screenshots at the bottom of this post.  None of the authors were contacted about their code’s use in the Retron5 hardware.



More evidence: (1, 2, 3, 4, 5, 6)

SNES9x Next

2. It uses the open-source emulator ‘SNES9x Next’, which is itself a derivative of SNES9x (https://github.com/libretro/snes9x-next). I (Squarepusher) personally made this version of SNES9x. It has a few differences compared to normal SNES9x. It has SuperFX overclocking code and it has certain game speed hacks that make games run faster on slower hardware. This comes at the expense of some graphics inaccuracies though.

We could tell it was the SNES9x Next core because the exact same strings for variables to do with the speed hacks and the SuperFX overclock code popped up in their SNES core.

SNES9x is licensed under a non-commercial license. Like Genesis Plus GX, it can therefore not be a part of a commercial product.

What also bears pointing out is that SNES9x Next has never been released in any other version than the libretro version. Libretro is the development interface of RetroArch if you remember. We will return to this later on.

Proof is in the accompanied screenshots (see below). None of the authors were contacted.




More evidence (1, 2, 3, 4, 5, 6).



3. It uses the open-source emulator ‘FCEUmm’ for its NES module, which is itself a derivative of FCE Ultra. FCEUmm is licensed under the GPLv2. Technically they would have been allowed to sell this IF they had made sure their frontend was compatible with GPLv2. Unfortunately, this turns out not to be the case as we’ll find later on – since they are using GPLv3 code inside their frontend as well which is technically incompatible with this license.

Proof of it being FCEUmm is in the accompanied screenshots (see below).

More evidence (1, 2, 3, 4, 5, 6)

VBA Next

4. It uses the open-source emulator ‘VBA Next’ for its GBA module. VBA Next is a derivative of another emulator called VBA-M. I (Squarepusher) made this version specifically and I could recognize it was this version because of the fact that I have built-in a game database into this emulator. The game ID strings that are used to identify the ROMs appeared in Retron’s GBA module as well. As for the rest of the code, it is undoubtedly VBA. The screenshots showing the code flow of operation will illustrate this clearest.

VBA Next is licensed under the GPLv2. None of the authors were contacted. Proof is in the accompanied screenshots (see below).


More evidence (1, 2, 3, 4, 5, 6)










5. We found obvious bits of RetroArch’s sourcecode inside their frontend. Now the reason we could identify these snippets is because it is inlined Assembly code that is hard to obfuscate. The relevant parts are the ARM NEON-optimized sinc resampler code and the audio integer to float conversion routines. If you want photographic evidence, I refer you to the second link I posted below.

All of the other C code of RetroArch seems to have been obfuscated so it will take us some more time to identify these parts. What is evidently clear though is that they are already in violation of the GPL license that we covered this RetroArch code under. GPL version 3 specifically forbids TIVO-ization. Let me explain later what TIVO-ization is. It basically means that you use opensource software to make a locked-down hardware device that doesn’t allow you the freedoms that the GPL generally provides to users and developers alike.

Since they have used our libretro cores evidently and since the only way to actually use these cores is through a libretro frontend implementation, and since actual RetroArch code has already been identified in their frontend, this raises serious questions as to how much of their frontend constitutes ‘original work’ and how much of it is just RetroArch. Either way, they are in the wrong for several reasons here:

– They should have also made these publicly available for every user to download since that is part of the rules and stipulations of using GPL code.
– They made a locked-down crippled hardware device based on open-source software. You void your warranty if you attempt to modify the copyleft-licensed software on this product and furthermore it doesn’t even allow you to do this.  It is not possible to run the original, non-crippled RetroArch frontend on this device, only the crippled one provided by HyperKin. It also uses encryption as a means to obfuscate and hide the originating source of this software. This is TIVO-ization and the GPL version 3 was specifically made to prevent this.

What is TIVO-ization?


Tivoization /ˈtiːvoʊɨˌzeɪʃən/ is the creation of a system that incorporates software under the terms of a copyleft software license (like the GPL), but uses hardware restrictions to prevent users from running modified versions of the software on that hardware. Richard Stallman coined the term in reference to TiVo’s use of GNU GPL licensed software on the TiVo brand digital video recorders (DVR), which actively blocks users from running modified software on its hardware by design.[1][2] Stallman believes this practice denies users some of the freedom that the GNU General Public License (GNU GPL) was designed to protect.[3]

The GPL version 3 was specifically made because GPL version 2 did not provide enough safeguards against abuse like in the case of the TIVo digital video recorders. They would take from open source, not credit anybody and not give anything back either – and even create a closed platform around it where they would set themselves up as owners of the software (and in effect the hardware).

GPLv3 forbids you from building a gated community around open-source software like this and giving nothing back in return. The fact that they have used RetroArch’s GPL version 3-licensed audio resampler code in a product that is running a locked-down, encryption-crippled version of Android is already bad enough. That they don’t even provide to users the ability to run content on this device without any restrictions is another serious concern.

Anyway, as it stands right now in its current state the product is using parts of our software illegally. There were also some other things found that were legally questionable like a Microsoft-licensed Verdana font which is covered by a End-User License Agreement, so there are multiple license violations here at play.

More evidence of RetroArch appropriation (1, 2, 3, 4, 5, 6, 7).

Multiple license violations, multiple conflicting licenses, bad faith

The problems with this are many-fold, but for us it comes down to mixing non-commercial cores on this device with more permissively licensed cores,  the infringement of the emulator authors’ rights, the lack of credit paid where credit is due, the lack of freedom in the hardware device (which restricts the user in what he/she can do and makes him/her reliant on Hyperkin to serve as the gateway keeper since he/she can’t uncripple this version of Android on their device without voiding their warranty and they can’t run the uncrippled RetroArch frontend on it either), and the multiple conflicting licenses. Also, the fact that changes / patches to the sourcecode have not been provided to customers of this device. These should have been made available on a public place free of charge.

Open-source is not a matter of doing with it as you please. The license is there for a reason and it needs to be followed, and it dictates how you should go about your business when deciding to make a commercial product out of such software. GPL is known as a ‘viral license’ which means that the community behind this uses the viral nature of the GPL as an effective strategy to ensure more and more software gets licensed under the GPL, since every bit of GPL code that gets incorporated into another project needs to be made GPL or GPL-compatible as well otherwise it’s a violation of the license. As it stands right now, the software for the Retron5 is very likely illegal to distribute.


1. http://imgur.com/a/T6W4e – This image gallery shows comparisons of the infringing derivative Retron code vs. the originals

2. https://www.anonimg.com/img/5d807718b069e5dae8a4e4320fdda1ab.png – This shows the RetroArch audio resampling and audio conversion routines in the Retron frontend

3. http://i.imgur.com/81bnckH.png – Another image of the audio resampling code. Originally from this tweet: https://twitter.com/FioraAeterna/status/512790355591196673

4. Regarding the MS Verdana font: http://www.microsoft.com/typography/fonts/font.aspx?FMID=1817 – “Verdana is either a registered trademark or a trademark of Microsoft Corporation in the United States and/or other countries.”

(EDIT: A section here about the ARM Mali drivers was removed since it appears to not be related to these issues)

(EDIT2 [9/20/2014]: Updated with more pics of evidence)