Homebrew [QUESTION] Why isn't there a way to load DS games off of the SD card yet?

[Deleted User]

NOTICE: I am a very large noob when it comes to things like this, so please, before biting my head off, please answer kindly.

So, I am just curious, because we have flashcarts that work, we have a dumper and a save tool, why can't we load DS games off of the 3ds' sd card?

I literally just tried using the fieldrunners exploit but replacing boot.nds with a game, but the game was obviously too large. I was wondering, (and yes, i know these things take time) why we can't use/make a boot.nds that takes control and allows us to load DS games. I have no idea how this process would be, but I would really like to see it happen.

I am expecting these comments:

Make it yourself.
-I would but I do not know how.

Things take time.
-I know and I am not wanting to rush anything or demand it, I just want to know why it isn't/wasn't possible

I would appreciate helpful insight instead of things relating to what I have just listed.

 

[coinblock]

Because DS flashcarts are like $20 total.

 

[_Chaz_]

Because the proper entrypoints haven't been found.
It's entirely possible that it'll never happen, but progress is being made.

 

[Deleted User]

Because DS games are hard-coded to load from SLOT-1. The only DS games games we can currently load off of an SD Card are those programmed to load the entirety of their contents into RAM and execute from there.
It is possible, though, and a workaround is currently in development.

 

[Deleted User]

Because DS games are hard-coded to load from SLOT-1. The only DS games games we can currently load off of an SD Card are those programmed to load the entirety of their contents into RAM and execute from there.
It is possible, though, and a workaround is currently in development.

Thank you for this answer.

 

[Roboman]

3ds games run pretty 'high-level'. That is, there's one or more layers of abstraction between the code and what the machine actually does.

DISCLAIMER
I didn't aim to get all the technical details even remotely accurate. Just threw together something to drive everyone's point.

A layman's example in pseudo pseudo code might be:

Spoiler: pseudo pseudo code

3ds game
Load file A from 3ds game
Load file B from 3ds game
...

It's pretty easy to convert cart games to installed games and vice-versa, because they are really slightly different formats for the same code.

While the Ds games would always run at the lowest level, on the hardware itself.

Example.
Ds game
Send READ_12345 to slot1 data bus.
Copy slot1 data bus to RAM_123
...
These games are hard coded to only read from one source. For dsiware games, that's fine, it's already there for us.
For Ds games, it reads from slot1. The only way we can put arbitrary data there is with a flashcard. It would be very hard to recompile Ds to dsiware because code looks identical to data at the lowest level: a series of zeroes and ones

 

[Deleted User]

There is a ds emulator in the works but there is not going to be any o3ds support for it.I doubt there will ever be a way to run ds roms natively without a flash cart since it only works with dsiware nativly at the moment and ds backwards compatability is only runnable through a game cart,so unless something comes out where you can trick the ds cart into running a ds rom through the sd card instead somehow it's impposable without a r4.

 

[RocketRobz]

There is a ds emulator in the works but there is not going to be any o3ds support for it.I doubt there will ever be a way to run ds roms natively without a flash cart since it only works with dsiware nativly at the moment and ds backwards compatability is only runnable through a game cart,so unless something comes out where you can trick the ds cart into running a ds rom through the sd card instead somehow it's impposable without a r4.

The DS emulator isn't being worked on anymore.

 

[Spiderkid08]

The DS emulator isn't being worked on anymore.

why not?

 

[RocketRobz]

why not?

Due to recent discoveries in DSi-mode, the emulator is dropped in favor of native ROM loading from SD, which is currently in development.

 

[Spiderkid08]

It's dropped in favor of native (DS mode) ROM loading from SD, which is currently in development.

wow that would be so neat to use, would it have 3dsx or just cia also retail roms or just homebrew?

 

[RocketRobz]

wow that would be so neat to use, would it have 3dsx or just cia also retail roms or just homebrew?

It's only for CFW users, so it's just CIA. And yes, it will run retail ROMs.

 

[Spiderkid08]

neat now i'll just wait until arm11/downgrade comes out. Im waiting and waiting and waiting and wai-

 

[Halvorsen]

[9000th post in the forum]

TWLfirm simply doesn't read game data off the SD. There is a thread floating around which you can track, which I'm looking for the link ATM.

 

[Spiderkid08]

[9000th post in the forum].

Congrats

 

[RocketRobz]

TWLfirm simply doesn't read game data off the SD. There is a thread floating around which you can track, which I'm looking for the link ATM.

This thread?: https://gbatemp.net/threads/ds-i-mode-hacking-progress-thread.413015/
Or the DS forwarders thread?: https://gbatemp.net/threads/nds-forwarder-cias-for-your-home-menu.426174/

 

[Halvorsen]

This thread?: https://gbatemp.net/threads/ds-i-mode-hacking-progress-thread.413015/
Or the DS forwarders thread?: https://gbatemp.net/threads/nds-forwarder-cias-for-your-home-menu.426174/

Yeah, the first, thanks.

 

[Swiftloke]

I know there have already been answers in this thread, but here are my two cents.

Yeah, basically what @undergroundmonorail said.
DS games have hardcoded reads to slot-1 whenever it loads its assets. Technically, you can convert a DS game to a CIA. This is what will happen:
-Load the code from the CIA.
-The code says to get its assets (things like graphics) from slot-1.
-There's nothing in slot-1. The code reacts like this:

(It crashes)
However, in our new expanded NTR mode we have DSi hardware access without breaking DS mode games. (TWL mode would normally break a DS game if you forced it to launch from it) All that's left for DS games off SD card is for devs to write an app that runs in a separate thread on the DSi mode hardware (while the game, of course, runs on the DS mode hardware) and patch out calls to slot-1 to the SD card. Obviously, this won't be easy at all, but it's doable.
I hope this answered any questions you had, @AntnioMoura

 

[Roomsaver]

I know there have already been answers in this thread, but here are my two cents.

What about (although it would probably take forever manually, a program could probably be written) patching the ROM itself to read from the SD?
EDIT: This has probably been said before 1,000,000 times.

 

[MoonUsotsuki]

What about (although it would probably take forever manually, a program could probably be written) patching the ROM itself to read from the SD?
EDIT: This has probably been said before 1,000,000 times.

If I understand right, the problem isn't the rom, but the way the system reads the data, therefore the need of modifying the system and so on