Andrey: The MMU uses burst access to DRAM. It might very well be that your burst patterns in the UPM memory are not quite correct. You can check this by setting the BIH bit in the ORx register for your DRAM. This will inhibit the use of UPM burst patterns and use single beat patterns instead. If your board now works after you enable the MMU, then you know where where to look.
Tony -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
