On Thu, Jan 22, 2026 at 5:13 PM Eric Dumazet <[email protected]> wrote: > > On Thu, Jan 22, 2026 at 4:52 PM Jakub Kicinski <[email protected]> wrote: > > > > On Thu, 22 Jan 2026 14:45:27 +0530 Srujana Challa wrote: > > > Increase VIRTIO_NET_RSS_MAX_KEY_SIZE from 40 to 52 bytes to align with > > > the kernel's standard RSS key length defined by NETDEV_RSS_KEY_LEN. > > > > I've been meaning to bump NETDEV_RSS_KEY_LEN to 128 or some such. > > Most modern drivers can't use netdev_rss_key_fill() either because > > core generates a tiny key. And the devices support hashing over two > > layers of IPv6 for tunnels. > > Seems fine to me. Back in 2014, RSS was limited to 52 bytes on all known NIC. >
BTW make it 256 bytes. 128 is already too small. > > > > Willem, WDYT? Is there a reason to keep the core key small? > > Or deprecate netdev_rss_key_fill()? > > What do you mean by deprecating it ? > > One of the ideas was to make sure multiple NIC would share the same key, > for some bonding setups. > > commit 960fb622f85180f36d3aff82af53e2be3db2f888 net: provide a per > host RSS key generic infrastructure > > > > > > > > The virtio specification requires devices to support at least 40 bytes > > > for the RSS key size. However, devices may support larger key sizes > > > up to 52 bytes (as reported by the device's rss_max_key_size config > > > field). This change allows such devices to work properly. > > > Previously, devices reporting rss_max_key_size > 40 would fail with > > > an error during initialization. > > > > > > The driver already handles variable key sizes dynamically through > > > vi->rss_key_size, so increasing the maximum limit is safe and > > > maintains backward compatibility with devices that support smaller > > > key sizes. > > > > > -#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40 > > > +#define VIRTIO_NET_RSS_MAX_KEY_SIZE 52
