Cory1492 released this DLDI firmware dumper just over a month ago. For some reason it did not make it to the news page or downloads section so I am adding it now.
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DLDI enabled tool that will dump your DS firmware, Arm7 and Arm9 bios to your device. For more info on what DLDI is, see here.
Currently only tested on a NA DSLite using EZ4LD GBA slot card and EZ5 DS slot card.
Source is not currently included, though if there are enough requests I would probably post it.
Based on: CaitSith’s arm7 asm code posted at GBATemp and a firmware dumper source that I no longer remember exactly where I found it.