Hi tonib,
Descriptor memory, according to its name, stores sgdma descriptors which are used to dma transfer tse data.
In your example probably this is separate onchip memory module: it is made this way to improve performance, so that sgdma has a dedicated memory channel for descriptors and must not find its way through interconnect matrix (and arbitration) to the main ram.
You could possibily avoid descriptor memory and connect everything to main ram: if I remember correctly, a separate descr mem is not mandatory for the altera sgdma driver.
Regards
