Hacking [Question] Using a custom R4.dat file on R4i-SDHC?

RocketRobz

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So I made a .nds file that boots into SRLoader.
I want to use it as R4.dat for autobooting into SRLoader, but I just get a "? Menu" screen.
So, I tried changing the arm7 entry offset to the one from the regular R4.dat file, and even DLDI-patching it, but same result.
There's probably something in the regular R4.dat file that's making the card accept it.
Anyone figured out how to run a custom R4.dat file?
 

Sha8q

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So I made a .nds file that boots into SRLoader.
I want to use it as R4.dat for autobooting into SRLoader, but I just get a "? Menu" screen.
So, I tried changing the arm7 entry offset to the one from the regular R4.dat file, and even DLDI-patching it, but same result.
There's probably something in the regular R4.dat file that's making the card accept it.
Anyone figured out how to run a custom R4.dat file?
Not sure if this will help, but I compared the YSMenu R4.dat and the normal YSMenu.nds to it. There were very few changes when I compared them, and only about eight bytes were different being five numbers or letters off.
 

DeadSkullzJr

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I know someone made tiny modifications to the ysmenu binary to get it working on r4isdhc.com and r4i-sdhc.com cards:

https://www.reddit.com/r/3dshacks/comments/48oju8/ys_menu_on_r4isdhccom_cards_as_primary_kernel/

Unfortunatelly, he did not disclose *how* he figured out what to change.
To be honest, I took a look into this myself. It seems the only thing he did was chance the file extension from .nds to .dat. So basically it looks like the file was renamed from YSmenu.nds to R4.dat. If you throw it in a hex editor and compare the .nds to the "modified" .dat, it practically is the same exact file. He may have removed some bytes or so to prevent it from breaking with any possible future YSmenu updates, that part I do not know.
 
Last edited by DeadSkullzJr,

Sha8q

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To be honest, I took a look into this myself. It seems the only thing he did was chance the file extension from .nds to .dat. So basically it looks like the file was renamed from YSmenu.nds to R4.dat. If you throw it in a hex editor and compare the .nds to the "modified" .dat, it practically is the same exact file. He may have removed some bytes or so to prevent it from breaking with any possible future YSmenu updates, that part I do not know.
That isn't the case, but you are close. I used the compare option in HxD which tells you any small difference. They are very similar though, and I really wonder how anyone figured this out. You are right for the similar part, I was amazed by how similar these files were. I actually tested the R4.dat on my R4iSDHC and my R4i-SDHC and the YSMenu autoboot works perfectly
 
Last edited by Sha8q,

DeadSkullzJr

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That isn't the case, but you are close. I used the compare option in HxD which tells you any small difference. They are very similar though, and I really wonder how anyone figured this out.
Ah, I didn't use that, I used the naked human eye lol. They probably did numerous tests and figured it out. I am actually trying to figure this out for some carts out there.
 

Sha8q

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Ah, I didn't use that, I used the naked human eye lol. They probably did numerous tests and figured it out. I am actually trying to figure this out for some carts out there.
Lol, when I tried to compare it with my eyes I saw nothing. Then I googled how to compare files on HxD (lol) and found the answer online.
 

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