Linux Virtualization - Apr 2023 - [PATCH vhost v6 08/11] virtio_ring: introduce virtqueue_dma_dev()

On Mon, 10 Apr 2023 20:26:20 -0700, Christoph Hellwig <hch at
infradead.org> wrote:
> On Tue, Apr 11, 2023 at 09:56:19AM +0800, Xuan Zhuo wrote:
> > Do you mean we should not change the dma_ops from the outside of the
core
> > kernel/dma/?
>
> Basically, yes.  That plus probing for the IOMMU drivers.
>
> > How about adding one new "dma_direct" to struct devive?
>
> Why would we?
>
> Can you please explain what you're even trying to do?
I want to force a device use direct dma map.

Thanks.
> But checking
> a dma_direct flag for sure isn't the solution.

> > Can you please explain what you're even trying to do?
> 
> I want to force a device use direct dma map.
You fundamentally can't do that.  It can't work.