On Wed, 2025-08-27 at 18:40 +0200, Johannes Berg wrote: > For sniffer also I guess it's just part of the chandef, which might also > require configuring/tracking the BSS color. Even if the sniffer could > listen on both control channels it'd still have to decide which to > decode, unless it's actually fully dual-channel. To elaborate a bit on this: To do sniffer the same way client does it, you need the BSS color and NPCA non-primary control channel. The latter is given by the chandef according the the rest of my proposal, but the BSS color isn't. Also, the BSS color can change, so what should be responsible for configuring it? And then maybe it shouldn't be a BSS color but BSSID instead? Etc. I mostly feel that this then isn't quite appropriate to put into the nl80211/cfg80211 API for sniffer configuration, since it might vary. We're probably going to implement it via just the BSS color in iwlwifi and assume it doesn't change, but maybe that should just remain in debugfs just like our AID configuration for multi-user sniffer? Another potential sniffer might even have more hardware (or synchronize two sniffer NICs) and be able to simultaneously receive on both the primary and non-primary control channels, seeing more frames and also the OBSS ones. For actually testing NPCA, this is probably required. Another possible hardware implementation might have enough hardware (chains) to do signal acquisition on both the primary and non-primary control channels simultaneously, but would then have to decide which one (# of chains and all that) which transmission to receive data, so it'd need the BSS color again? So I'm mostly tending towards just not having this in the sniffer for cfg80211 level and doing something in debugfs if we need it. However, the flip side is that two UHR stations communicating on a 320 MHz channel might send data via NPCA that even a sniffer configured to the same 320 MHz channel couldn't see. But without BSS color configuration it's impossible for it to see that anyway, so you'd have to decide which stations you want to see unless there are effectively separate sniffers ... johannes
