On Sun, Apr 7, 2024 at 2:03 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > On Sun, 7 Apr 2024 12:24:00 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > On Mon, Apr 1, 2024 at 11:10 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > On Mon, 1 Apr 2024 09:40:07 +0800, Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > On Fri, 29 Mar 2024 11:20:08 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > > On Thu, Mar 28, 2024 at 4:27 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > On Thu, 28 Mar 2024 16:05:02 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > > > > On Wed, Mar 27, 2024 at 7:14 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > Now, the virtio core can set the premapped mode by find_vqs(). > > > > > > > > If the premapped can be enabled, the dma array will not be > > > > > > > > allocated. So virtio-net use the api of find_vqs to enable the > > > > > > > > premapped. > > > > > > > > > > > > > > > > Judge the premapped mode by the vq->premapped instead of saving > > > > > > > > local variable. > > > > > > > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> > > > > > > > > --- > > > > > > > > > > > > > > I wonder what's the reason to keep a fallback when premapped is not enabled? > > > > > > > > > > > > Rethink this. > > > > > > > > > > > > I think you are right. We can remove the fallback. > > > > > > > > > > > > Because we have the virtio dma apis that wrap all the cases. > > > > > > So I will remove the fallback from the virtio-net in next version. > > > > > > > > > > Ok. > > > > > > > > > > > > > > > > > But we still need to export the premapped to the drivers. > > > > > > Because we can enable the AF_XDP only when premapped is true. > > > > > > > > > > I may miss something but it should work like > > > > > > > > > > enable AF_XDP -> enable remapping > > > > > > > > > > So can we fail during remapping enablement? > > > > > > > > > > > > YES. > > > > > > > > Enabling the premapped mode may fail, then we must stop to enable AF_XDP. > > > > > > > > AF-XDP requires that we export the dma dev to the af-xdp. > > > > We can do that only when the virtio core works with use_dma_api. > > > > Other other side, if we support the page-pool in future, we may have the > > > > same requirement. > > > > > > Rethink this. > > > > > > Enable premapped MUST NOT fail. No care the use_dma_api is true or not, because > > > we have the DMA APIs for virtio. Then the virtio-net rx will work with > > > premapped (I will make the big mode work with premapped mode) > > > > Just to make sure we're at the same page. Rx will always work in the > > mode or pre mapping. So we can easily fail the probe if we fail to > > enable RX premapping? > > > NO, enabling premapped mode can not fail. So the rx will always work > in the premapping mode. Ok, kind of my understanding. > > > > > > > > > > AF_XDP checks the virtqueue_dma_dev() when enabling. > > > > > > But disabling premapped mode may fail, because that virtio ring need to > > > allocate memory for dma. > > > > That's kind of too tricky, what if we just allocate the memory for dma > > unconditionally? > > It's ok, but we waste the memory. Probably, but the point is to reduce the complexity of the codes for symmetry: We don't need to have and maintain codes for fallback mode when we fail to disable premapping. Thanks > > Thanks. > > > > > > > Thanks > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > THanks > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > > > > > > > > >
