NDS for DSi

I had announced on some discord channels that I had a new NDS demo of my ongoing work. One of these channels is the one where I'm in touch with Fei, who already tried a copy of the 3-rooms demo back in 2021 and 2023.

Back then, we finally managed to have something running at his place, but it doesn't seem it has been preserved. After locating a register that could tell me whether we're running on DSi (and then skipping the InitGBA function that would blue screen the demo -- as there are no GBA memory around), the best I could get is a "EFS search failed" message, but also a mention that 1) DLDI is around but 2) the demo is installed on Fei's SD card rather than in the filesystem.

Bad news is that I don't see anything in libfat or in libnds that would enable DSi' SD card access, which goes through completely separate hardware and isn't covered by DLDI at all (to my best knowledge). I'm not the only one to have such problems, but there was no answers to be found.

So I guess my best move to make progress there is finally to get homebrew software running on my own DSi thanks to StyleHax...  for that, the next step was to enable a DNS server on the cube. That sounded like a task the rubber duck could take care of and it suggested the following: 

Use a small local DNS resolver (dnsmasq or unbound) bound to the interface and configure only the few hosts to use it via per-interface/etc resolver settings or systemd-resolved split DNS. Since you want minimal config/deps on Ubuntu 18.04, dnsmasq is simplest.

• Edit /etc/dnsmasq.conf (or add /etc/dnsmasq.d/custom.conf) and add: 
• interface=eth1 # replace with your interface name 
• bind-interfaces # ensure dnsmasq binds only to listed interface 
• listen-address=192.0.2.10 # IP of that interface (optional, stronger) 
• no-resolv # avoid reading /etc/resolv.conf 
• add local hostnames: address=/host1.example/192.0.2.101 address=/host2.example/192.0.2.102 

ok, fine. That allowed me to fake some website with some other DNS name, and eventually get stylehax page shown on the DSi, even once making a green screen (exploit worked, but boot.nds was missing) and once loaded the dumptool.nds, but it complained the SD card was too small (it's a 128MiB one) and refused to do anything. Each attempt takes 1-2 minutes, and I'd say the success rate is at best 1:10.

One of my ideas was to use e.g. runME as boot.nds and work directly from there, but from this experience, it doesn't seem to be a viable plan ...  

Maybe I should pay a closer look to the updated nds_loader ? 

Maybe I should check the way GetDeviceOpTab is implemented and try to write something that reports all available devices ? (alt. repo from Patater)

Or maybe I should simply use another hack ? like the Memory Pit for the camera application ?