On Wed, Aug 20, 2025 at 10:13 AM Dragos Tatulea [off-list ref] wrote:

For zerocopy (io_uring, devmem), there is an assumption that the
parent device can do DMA. However that is not always the case:
- Scalable Function netdevs [1] have the DMA device in the grandparent.
- For Multi-PF netdevs [2] queues can be associated to different DMA
devices.

This patch introduces the a queue based interface for allowing drivers
to expose a different DMA device for zerocopy.

[1] Documentation/networking/device_drivers/ethernet/mellanox/mlx5/switchdev.rst
[2] Documentation/networking/multi-pf-netdev.rst

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

Reviewed-by: Mina Almasry <redacted>

-- 
Thanks,
Mina