Michał Kazior <kazi...@gmail.com> writes: > On Wed, 28 Nov 2018 at 13:39, Toke Høiland-Jørgensen <t...@toke.dk> > 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).
Yeah, good point! >> 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). Oh boy. I figured it was going to be a can of worms; didn't realise it was quite that big :/ -Toke
