On Sat, 11 Jul 2020, Michael S. Tsirkin wrote: > On Fri, Jul 10, 2020 at 10:23:22AM -0700, Stefano Stabellini wrote: > > Sorry for the late reply -- a couple of conferences kept me busy. > > > > > > On Wed, 1 Jul 2020, Michael S. Tsirkin wrote: > > > 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.. > > > > Yes, DMA API is broken with some interfaces (specifically: rpmesg and > > trusty), but for them PLATFORM_ACCESS is never set. That is why the > > errors weren't reported before. Xen special case aside, there is no > > problem under normal circumstances. > > So why not fix DMA API? Then this patch is not needed.
It looks like the conversation is going in circles :-) I tried to explain the reason why, even if we fixed the DMA API to work with rpmesg and trusty, we still need this patch with the following email: https://marc.info/?l=linux-kernel&m=159347446709625&w=2 At that time it looked like you agreed that we needed to improve this check? (https://marc.info/?l=linux-kernel&m=159363662418250&w=2) _______________________________________________ iommu mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/iommu