Re: [RFC PATCH 1/3] RDMA/umem: Change for rdma devices has not dma device

[Shunsuke Mie]

Thank you for your comment.
>
> On Wed, Sep 08, 2021 at 03:16:09PM +0900, Shunsuke Mie wrote:
> > To share memory space using dma-buf, a API of the dma-buf requires dma
> > device, but devices such as rxe do not have a dma device. For those case,
> > change to specify a device of struct ib instead of the dma device.
>
> So if dma-buf doesn't actually need a device to dma map why do we ever
> pass the dma_device here?  Something does not add up.
As described in the dma-buf api guide [1], the dma_device is used by dma-buf
exporter to know the device buffer constraints of importer.
[1] https://lwn.net/Articles/489703/