On Fri, Jun 04, 2021 at 08:58:05AM -0300, Jason Gunthorpe wrote: > On Fri, Jun 04, 2021 at 09:11:03AM +0800, Jason Wang wrote: > > > nor do any virtio drivers implement the required platform specific > > > cache flushing to make no-snoop TLPs work. > > > > I don't get why virtio drivers needs to do that. I think DMA API should hide > > those arch/platform specific stuffs from us. > > It is not arch/platform stuff. If the device uses no-snoop then a > very platform specific recovery is required in the device driver. Well, the proper way to support NO_SNOOP DMA would be to force the DMA API into supporting the device as if the platform was not DMA coherent, probably on a per-call basis. It is just that no one bothered to actually do the work an people just kept piling hacks over hacks.
