Recently working on a PCI driver project and trying to understand the Scatter Gather DMA.
In my project, the PCI device(in a PC's PCI slot) is the DMA master and I want to do a DMA write to the PC's memory. For a scatter/gather dma, so PC driver should creat a linked list for those "non contiguous" or also called "segmented" physical memory, and write the first address of the linked list to the device. so the device's dma controler can do the write operation through the linked list without asking the PC for the next free memory block. am I write?
In the senario above, there is an expression "wrap around" envolved, and I can't be sure what does it mean.
Does it mean: the write pointer reached the end of the memory block?
the current data packet to be send is done sending and should start the next one ?
some other thing?