On 1/7/21 10:00 AM, Konrad Rzeszutek Wilk wrote: >>> >>> >>> - Nothing stops the physical device from bypassing the SWIOTLB buffer. >>> That is if an errant device screwed up the length or DMA address, the >>> SWIOTLB would gladly do what the device told it do? >> >> So the system needs to provide a way to lock down the memory access, e.g. MPU. > > OK! Would it be prudent to have this in the description above perhaps? Yes this is something that must be documented as a requirement for the restricted DMA pool users, otherwise attempting to do restricted DMA pool is no different than say, using a device private CMA region. Without the enforcement, this is just a best effort. -- Florian
