Hacking M3 Lite and homebrew requires R4 DLDI?

Another World

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I have noticed that some homebrew (ScumMVM DS, C|irc) must be DLDI patched for the R4 when running them off my M3 Lite and using the R4 as my passme device. I have noticed that these homebrew apps use the R4 as their root directory. I don't understand why this happens, and assume it is perhaps the way they are coded.

This really is not an issue for C|irc as it is only storing a few tiny files on the R4. However, with ScumMVM DS the app is looking to the R4 for the game files. I would perfer that it looks to the M3 lite. Is there no way to accomplish this? Why does this happen when the R4 is the passme device?

This is more of an annoyance right now than anything else. I am trying to keep my "retro" gaming (Nes/Snes/Genesis/ScummVM/etc) on the M3 Lite as well as my homebrew, while using the R4 just for .nds rom files.

Some Testing:
C|irc 1.04

Will only run if it is patched for the R4. If I patched it for the M3 using either of the 2 known DLDI patches I get a filesystem error screen letting me know that I'm using the wrong DLDI. However, the app is running off of the M3 Lite so this really confuses me.

Pocketphysics 0.4

Patched for the R4 but running off of the M3 Lite, saved files are saved to the R4. Patched for the M3 Lite and running off the M3 Lite, saved files are saved to the M3 Lite.

Does this mean that the R4 isn't working to "pass" data to slot1 but actually rendering the app? It is highly possible that I am not fully understanding what the DLDI library is doing and/or the specific homebrew in general.

I am currently using Dlditool-win32-gui to DLDI patch but have used DLDIrc in the past with the same results. I have tried the above tests using both normally patched apps and versions patched using Dldino-apatch which adds the "NO" re-patch fix.

If anyone can suggest what I could do or have experienced this problem and understands why, would you be so kind to post back?

Thanks,
-AW
 

Destructobot

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When you apply the R4 DLDI patch the app uses the R4 filesystem, because that's what the R4 DLDI driver does.

Does the M3 DLDI driver work if you use a different NoPass? If so, you could try using a Superkey rom to boot the M3 in DS mode rather than the R4's NoPass feature. You can get a superkey rom from one of the Supercard DS1 service packs in the GBAtemp download center.
 

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Destructobot: Thank you for the reply.

I do not own another passme device to give it a try. The only reason I stumbled across this DLDI issue is because some apps do not work when patched for the M3 Lite (using the M3 DLDI). ScummVM tells me that I do not have the correct DLDI driver patched. I have tried both available versions of the M3 DLDI driver. I wonder if the M3 Lite requires something more. Any rate I had to patch c|irc with the R4 patch to get it to run correctly, so I tried this with ScummVM. It now starts and loads but is using the R4 file system as stated.

I suppose there is no way around this issue then accept to run it off the R4.

I will look into the SuperKey rom and see if running that off of my R4 will allow me to boot my M3 Lite. I fear that if the DLDI patch isn't working this won't do much to fix my problem.

What you are saying then is that the NDS is simply looking at the ROM which is now patched for the R4 and thus writing all the save/load information to the R4 even though the ROM is running off the slot2 device? This is because the R4 DLDI information points to the R4 device no matter where the ROM was originally booted from?

Thanks,
-AW
 

Destructobot

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This is because the R4 DLDI information points to the R4 device no matter where the ROM was originally booted from?
Yes. The R4 DLDI patch only allows access to the R4's filesystem. Likewise, if you patched a homebrew with the M3SD DLDI patch using No-AutoPatch and ran it from the R4, it would read and write files from the M3.

I looked at the ScummVM DS homepage, and it says that you have to run the .nds file by pressing A, it won't work if you run it by pressing start.

You're using one of the M3SD DLDI drivers, not the M3CF or M3 Real drivers? These are the correct drivers for the M3 Lite: http://dldi.drunkencoders.com/index.php?ti...r_%28SD_Card%29
 

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Yes I am using the M3 SD DLDI driver patches. It appears that now ScummVM DS is working using the ALT patch. I am always sure to make multiple copies of the unpatched .nds file and then patch with various versions and the R4 patch, and then test to see what works. I could have easily screwed this up and double patched something or did something else along the way.

I could have sworn I didn't mess up, and both M3 SD patches failed. Oh well, debugging this is half the fun of homebrew (at times).

Thank you for your replies and the information. I have a better idea of how the DLDI system functions now. Now I just need to talk to Cluster again and let him know that the DLDI patch for the M3 SD and C|irc is not working =).

*cheers*
-AW
 

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