Ok yeah I should have included a bit more info to begin with. First, I will defend my assertion, then I will give more details on the motivation behind this patch. 802.11ax-2021 §26.17.2.1 - "A STA that supports operation in the 6 GHz band sets dot11HE6GOptionImplemented to true." "A STA 6G shall not transmit an HT Capabilities element, VHT Capabilities element, HT Operation element, VHT Operation element, or an HE Operation element that contains a VHT Operation Information field." "A STA 6G shall not transmit an HT PPDU." "A STA 6G shall not transmit a VHT PPDU." In other words, 6GHz is for HE and EHT operation only. Legacy operation is not permitted. 802.11ax-2021 §26.17.1 - "An HE STA operating in the 6 GHz band is a VHT STA, except that it is exempt from following VHT and HT functionalities and/or requirements that are not applicable or that are superseded by equivalent HE functionalities and/or requirements (see Clause 26 and Clause 27) and except that it shall use the HE format instead of the VHT, HT_GF, or HT_MF format for PPDUs transmitted in the 6 GHz band. Additional HE functionalities and/or requirements for the 6 GHz band are defined in 26.17.2." Likewise, a VHT STA is an HT STA, and an HT STA is a QoS STA. In 2.4 / 5 GHz, WiFi is fully backward compatible with legacy standards. When a beacon frame is captured in the lower spectrum that is missing the WMM IE, authentication / association can still proceed, but communication will be limited to non-HT rates. In 6 GHz, the chain of backwards compatibility is broken. WiFi devices operating in 6 GHz must at minimum support HE. And all HE STA must support WMM/QoS. So the current logic in mac80211 to downgrade to legacy in absence of the WMM IE is flawed when the beacon is captured on 6 GHz, because any STA operating in 6 GHz must be at least implement HE and all of its required features. One more supporting item from the spec. 802.11-2020 §10.2.3.2 - "The QoS AP shall announce the EDCA parameters in selected Beacon frames and in all Probe Response and (Re)Association Response frames by the inclusion of the EDCA Parameter Set element using the information from the MIB entries in dot11EDCATable. If no such element has been received (e.g., prior to association in an infrastructure BSS), a non-AP QoS STA shall use the default values for the parameters." So it is explicitly stated that it is possible that a beacon frame can be received from a QoS AP without the EDCA parameters included. And since a non-AP STA cannot initiate a probe request with a wildcard for the SSID in 6 GHz, it has no choice but to use the default parameter values outlined in the spec until the QoS AP instructs otherwise. Now for my motivation for introducing this patch. I have observed that the WMM element is not present in beacon frames in the 6 GHz spectrum on the Ruckus R770 when multiple BSSs are packed together using the MBSSID feature. The WMM IE is included in the top-level profile, but not in the non-Tx profiles defined within the MBSSID element. I am in contact with support, but the initial response I got from Ruckus is that this is intentional. And well it makes sense I guess. If the spec defines default values, and the whole point behind MBSSID is to save airtime for data transmission, then why repeat the same unchanged default QoS values for every BSS. I also figured that they had to go through a lot to get the WiFi 7 certification. If this is truly an error, I would be surprised if I'm the first to notice it, given that the R770 shipped out beginning in 2023 :) So I dug through the spec, and ended up with this chain of reasoning for why the WMM IE is not required in 6 GHz. Jeff On Tue, Sep 9, 2025 at 9:57 AM Johannes Berg <johannes@xxxxxxxxxxxxxxxx> wrote: > > On Tue, 2025-09-09 at 09:55 -0400, Jeff Isaacs wrote: > > In 6 GHz, QoS/EDCA operation is mandatory as per IEEE 802.11ax/802.11be. > > APs are not required to include a WMM Information or WMM Parameter > > element in Beacon or Probe Response frames, unlike in 2.4/5 GHz. > > Instead, stations must assume that QoS is always enabled and use EDCA > > (default EDCA parameters apply if no explicit EDCA Parameter Set is > > present). > > What? You really need to back up that assertion. > > johannes
