Re: [RFC RESEND 00/16] Split IOMMU DMA mapping operation to two steps

Leon Romanovsky
2024-03-13T07:46:41Z

On Tue, Mar 12, 2024 at 10:28:44PM +0100, Christoph Hellwig wrote:
> On Sun, Mar 10, 2024 at 11:35:13AM +0200, Leon Romanovsky wrote:
> > And you will need to have a way to instruct that pin_user_pages() variant
> > to continue anyway, because you asked for FOLL_PCI_P2PDMA. Without that
> > force, you will have !FOLL_PCI_P2PDMA behaviour.
>
> I don't understand what you mean.

Jason talked about the need to call to pin_user_pages(..., gup_flags | FOLL_PCI_P2PDMA, ...),
but in your proposal this call won't be possible anymore.

>
> > When you say "simplify the overall interface", which interface do you mean?
>
> Primarily the dma mapping interface. Secondarily also everything around
> it.

OK, thanks