On Fri, 5 Apr 2019, Halil Pasic wrote: > To support protected virtualization cio will need to make sure the > memory used for communication with the hypervisor is DMA memory. > > Let us introduce a DMA pool to cio that will help us in allocating > deallocating those chunks of memory. > > We use a gen_pool backed with DMA pages to avoid each allocation > effectively wasting a page, as we typically allocate much less > than PAGE_SIZE. I don't think we should use this global DMA pool. I guess it's OK for stuff like airq (where we don't have a struct device at hand) but for CCW we should use the device we have. Yes, this way we waste some memory but all dma memory a device uses should fit in a page - so the wastage is not too much. Sebastian
