On Wed, 28 Nov 2018 at 13:39, Toke Høiland-Jørgensen <toke@xxxxxxx> wrote:[...] > > This is an early stage implementation, at this point I would collect > > other people opinions/concerns about using bpf/xdp directly on 802.11 > > frames. > > Thanks for looking into this! I'm really hyped up with this especially when I think this could be maybe offloaded to wlan cpu's for e.g. deep powersaving (allow host system to suspend) without relying on blackbox logic you get today, or 802.11 -> 802.3 conversion (to offload host cpu). > I have two concerns with running XDP on 802.11 frames: > > 1. It makes it more difficult to add other XDP actions (such as > REDIRECT), as the XDP program would then have to make sure that the > outer packet headers are removed before, say, redirecting the packet > out of an ethernet interface. Also, if we do add redirect, we would > be bypassing mac80211 entirely; to what extent would that mess up > internal state? > > 2. UI consistency; suddenly, the user needs to know which kind of > frames to expect, and XDP program reuse becomes more difficult. This > may be unavoidable given the nature of XDP, but some thought needs to > go into this. Especially since we wouldn't necessarily be consistent > between WiFi drivers (there are fullmac devices that remove 802.11 > headers before sending up the frame, right?). Yep - you can expect 802.3 frames or amsdu subframes (DA+SA+length) too. In some cases you could also expect internal events (broadcom if I understand their fullmac arch). Michał
