On Wed, Dec 22, 2021 at 12:37:03PM +0000, Hyeonggon Yoo wrote: > Oh I misunderstood this. Underlying physical address of vmalloc()-allocated memory > can be mapped using DMA API, and it needs to be setup as scatterlist because > the allocated memory is not physically continuous. Right? Yes. > BTW, looking at the API I think the scsi case can be converted to use > dma_alloc_pages(). but driver requires 512 bytes of buffer and the API > supports allocating by at least page size. Overallocating is not generally a problem, but if the allocations are for a slow path it might make more sense to stick to dma_map_* and bounce buffer if needed. > It's not a big problem as it allocates a single buffer but in other > cases maybe not. Can't we use dma pool for non-coherent pages? No.
