On Tue, Nov 17, 2020 at 02:02:30PM +0000, Christoph Hellwig wrote: > On Tue, Nov 17, 2020 at 03:00:32PM +0100, Arnaud POULIQUEN wrote: > > The dma_declare_coherent_memory allows to associate vdev0buffer memory region > > to the remoteproc virtio device (vdev parent). This region is used to allocated > > the rpmsg buffers. > > The memory for the rpmsg buffer is allocated by the rpmsg_virtio device in > > rpmsg_virtio_bus[1]. The size depends on the total size needed for the rpmsg > > buffers. > > > > The vrings are allocated directly by the remoteproc device. > > Weird. I thought virtio was pretty strict in not allowing diret DMA > API usage in drivers to support the legacy no-mapping case. Well remoteproc is weird in that it's use of DMA API precedes standartization efforts, and it was never standardized in the virtio spec .. > Either way, the point stands: if you want these magic buffers handed > out to specific rpmsg instances I think not having to detour through the > DMA API is going to make everyones life easier.
