DreamShell 4.0 RC 4

[SWAT]

Yes, DMA is required for MMU games, because only DMA has access to memory in this case, MMU is not only memory mapping, it's a memory protection too.
In some KATANA games (seems in latest games) MMU used only as protection.
But this is not the only reason why WinCE games have not worked. There are a lot of nuances which had to be solved. For example old loader does not support some syscalls and WinCE interrupts hack.

By this reason MMU games can't work on SD card, for it need some workaround code... much code. No free memory for it now
Also it's hard to make CDI or not optimized GDI get works in this case too.
Really it's can be done, but will works slow, because need use sector by sector reading, for skip unused data of sectors.

All of this makes some requirements for boot MMU games - ISO or optimized GDI images and device with DMA support.

Not sure what I understand your question., but blocked DMA has little effect on compatibility, it has a greater effect to the lags at reading.