On Sun, Apr 23, 2023 at 12:28:49PM +0000, Alvaro Karsz wrote: > > > > > The rest of stuff can probably just be moved to after find_vqs without > > > > much pain. > > > > > > > Actually, I think that with a little bit of pain :) > > > If we use small vrings and a GRO feature bit is set, Linux will need to allocate 64KB of continuous memory for every receive descriptor.. > > > > Oh right. Hmm. Well this is same as big packets though, isn't it? > > > > Well, when VIRTIO_NET_F_MRG_RXBUF is not negotiated and one of the GRO features is, the receive buffers are page size buffers chained together to form a 64K buffer. > In this case, do all the chained descriptors actually point to a single block of continuous memory, or is it possible for the descriptors to point to pages spread all over? > > > > > > Instead of failing probe if GRO/CVQ are set, can we just reset the device if we discover small vrings and start over? > > > Can we remember that this device uses small vrings, and then just avoid negotiating the features that we cannot support? > > > > > > We technically can of course. I am just not sure supporting CVQ with just 1 s/g entry will > > ever be viable. > > Even if we won't support 1 s/g entry, do we want to fail probe in such cases? > We could just disable the CVQ feature (with reset, as suggested before). > I'm not saying that we should, just raising the option. > So, let's add some funky flags in virtio device to block out features, have core compare these before and after, detect change, reset and retry? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
