Alan Stern wrote: > if we can directly map the user-provided buffer for DMA.
Given a memory buffer either kernel or userspace has to apply the hardware constraints to find out what part if any is usable for DMA. I think it's fine to push this task to userspace - as long as userspace has a way to take care of it. That means userspace must be able to perform an allocation according to the constraints. I don't think this is currently possible. Is that correct? The kernel could certainly do the allocation and hand the buffer to userspace. Wiping the buffer once upon allocation is a reasonable cost, because this allocation should be long-lived. > On the other hand, adding an API that allows users to allocate low > memory and then hiding it in the USB subsystem doesn't seem like a > good idea. Unless another generic API already supports the neccessary constraints then what other options are there? //Peter -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
