Re: [PATCH] xen: introduce xen_vring_use_dma

From: Michael S. Tsirkin
Date: Wed Jul 01 2020 - 17:23:44 EST


On Wed, Jul 01, 2020 at 10:34:53AM -0700, Stefano Stabellini wrote:
> Would you be in favor of a more flexible check along the lines of the
> one proposed in the patch that started this thread:
>
> if (xen_vring_use_dma())
> return true;
>
>
> xen_vring_use_dma would be implemented so that it returns true when
> xen_swiotlb is required and false otherwise.

Just to stress - with a patch like this virtio can *still* use DMA API
if PLATFORM_ACCESS is set. So if DMA API is broken on some platforms
as you seem to be saying, you guys should fix it before doing something
like this..

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MST