Homebrew [RELEASE] NTRLDR - DS firmware on the 3DS

[dr1ft]

Hello!
I've been very intrigued as to why the old firmware.nds file failed to load properly under the 3DS. After almost a week of research and experimentation, I took my first dive into writing homebrew as a means to solve this problem. It's not particularly useful, but I learned a lot and it's a neat little novelty.

I've tested NTRLDR heavily under an NTR-mode flashcart (CycloDS iEvolution) and under TWL-mode nds-hb-menu (3DS SD). It does not seem to run under TWLoader/nds-bootstrap. firmware.nds is expected to be in the root of the partition /_nds/ntrldr

I do not recommend running this on an NDS or DSi system. It probably won't hurt anything, but it directly writes to flash/NVRAM (which is dangerous) and there's no real reason to (unless you are using SudokuHax or something). It will almost certainly brick an iQue NDS.

YOU CANNOT BOOT NDS CARTRIDGES WITH THIS

Here's a tiny little demonstration:

Spoiler: Technical details

NVRAM patching
The reason that firmware.nds traditionally fails on the 3DS is because for some reason NVRAM reports one of the bits in the flag bytes of user settings as a 1, when the DS firmware expects that bit to be a 0. We can write to NVRAM, but every time NTR mode is restarted this bit becomes a 1 again. As such, all we need to do to allow firmware.nds to boot is to flip that bit and correct the checksums in the user settings just prior to chainloading firmware.nds.

TWL->NTR mode switching
The NDS firmware does not know how to deal with the extra features provided by TWL mode (obviously). The DMA register REG_SCFG_ROM is set to 0x703 to keep the firmware from crashing (this seems to cause the system to disable several TWL features) and writes are made to the TSC to switch it into NDS compatibility mode (see here) so that the firmware can understand the touch screen. I found the TSC values by going through this code and trying different combinations of values until I found the right ones.

DOWNLOAD: https://github.com/strdr1ft/ntrldr
I can't supply firmware.nds, but it's not too hard to find if you're interested in trying this.

 

[Favna]

PictoChat is worth every minute you spend on this

 

[Deleted User]

Hello!
I've been very intrigued as to why the old firmware.nds file failed to load properly under the 3DS. After almost a week of research and experimentation, I took my first dive into writing homebrew as a means to solve this problem. It's not particularly useful, but I learned a lot and it's a neat little novelty.

I've only tested NTRLDR on a flashcart on my CFW'd O3DS. I don't know if it works on TWLoader. If someone tests it and finds that it does, let me know.
firmware.nds is expected to be in the root of the partition.
Oh, and don't run this on DSi or NDS, and backup your NVRAM! I've played with it enough that I feel confident in its safety, but it has the potential to disable TWL mode on the 3DS and even worse on NDS and DSi!!

Here's a tiny little demonstration:

Spoiler: Technical details

The reason that firmware.nds traditionally fails on the 3DS is because for some reason NVRAM reports one of the bits in the flag bytes of user settings as a 1, when the DS firmware expects that bit to be a 0. We can write to NVRAM, but every time NTR mode is restarted this bit becomes a 1 again. As such, all we need to do to allow firmware.nds to boot is to flip that bit and correct the checksums in the user settings just prior to chainloading firmware.nds.

NTRLDR: hxxps://mega.nz/#!KQhTEKaC!fSddkDujotraSc-lycJYu6VNbie_v6eXCGWQnq6aFQI (I can't post hyperlinks)
I can't supply firmware.nds, but it's not too hard to find if you're interested in trying this.

Liking the great work

 

[RocketRobz]

Nice!
Can you please post the source code?

 

[dr1ft]

Nice!
Can you please post the source code?

Sure thing, I'd just like to clean it up a little beforehand. I'll throw it up on GitHub most likely later today or maybe tomorrow (as I haven't slept last night from working on this)

 

[TR_mahmutpek]

İts better than emulating the ds, right?
İf it is, hats off

 

[The Real Jdbye]

PictoChat is worth every minute you spend on this

I think the DSi version of PictoChat already worked.

 

[Favna]

I think the DSi version of PictoChat already worked.

sssshhhhhhh

 

[IC_]

I love it

 

[Dante2405]

When in the homebrew, can we launch a DS game if it's in the slot?
Could it be launch as a .cia?

Great work!

 

[dr1ft]

When in the homebrew, can we launch a DS game if it's in the slot?

No, firmware.nds doesn't support loading anything from Slot-1

Could it be launch as a .cia?

At this moment, I don't think so because of how it works.

 

[dr1ft]

GitHub repo is live now

 

[Asia81]

PictoChat is worth every minute you spend on this

How many hours I spent on it, when I had no games (when I was kid, I didn't know linker and cfw was a thing)
Taking 2h to fill the screen in black, then take 2s to clean it

 

[Jimbo_Slim]

This makes the 2 half broken DS' in my room cry.

 

[Technicmaster0]

Nice to see that there are still people that have and use a cyclods ievolution

 

[dr1ft]

UPDATE: it loads perfectly from hb-menu installed as a CIA but I've had poor luck with getting nds-bootstrap to work on my 3DS in general

 

[RocketRobz]

UPDATE: it loads perfectly from hb-menu installed as a CIA but I've had poor luck with getting nds-bootstrap to work on my 3DS in general

It doesn't work from TWLoader, because it always uses nds-bootstrap to boot homebrew. Try running it from SRLoader.

 

[DRAGONBALLVINTAGE]

Have you tried it one a real DSi?

 

[dr1ft]

OK, it actually doesn't like being booted from hb-menu.
It boots but struggles with being in DSi mode .-.

Touch screen doesn't work, sound is messed up, and making any menu selections triggers a crash.

 

[DRAGONBALLVINTAGE]

OK, it actually doesn't like being booted from hb-menu.
It boots but struggles with being in DSi mode .-.

Touch screen doesn't work, sound is messed up, and making any menu selections triggers a crash.

Thanks