On Sun, 12 Nov 2023 19:28:52 -0800 Mina Almasry wrote:

My issue with this is that if the driver doesn't support dmabuf then the driver will accidentally use the pp backed by the dmabuf, allocate a page from it, then call page_address() on it or something, and crash.

Currently I avoid that by having the driver be responsible for picking up the dmabuf from the netdev_rx_queue and giving it to the page pool. What would be the appropriate way to check for driver support in the netlink API? Perhaps adding something to ndo_features_check?

We need some form of capabilities. I was expecting to add that as part of the queue API. Either a new field in struct net_device or in ndos. I tend to put static driver caps of this nature into ops. See for instance .supported_ring_params in ethtool ops.