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From:   Ramon Fontes <ramonreisfontes@gmail.com>
Date:   Thu, 29 Aug 2019 14:04:19 -0300
Message-ID: <CAK8U23aHprXtZm2PV3sj6g4Da_ponK9L0YmSO1tb6xoFgK-ZLA@mail.gmail.com>
Subject: Re: mac80211_hwsim (kernel 4.18+): wmediumd + 2.4Ghz
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     linux-wireless@vger.kernel.org
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Yes, that's what I (we?) expect.

Yes, wmediumd has some log files, but they don't help me to identify
the reason of the problem. I also unsuccessfully tried to modified the
wmediumd code. Both wmediumd and mac80211_hwsim work fine up to kernel
version 4.17. The problem comes only from kernel 4.18. Since there are
some wmediumd related-codes in mac80211_hwsim, I was wondering whether
something wasn't missing in mac80211_hwsim (or even some needed
changes in wmediumd) that is causing such problem. Another weird thing
is the channel, since the channel is the same as defined in hostapd
and doesn't match 5Ghz channels.


On Thu, Aug 29, 2019 at 11:57 AM Johannes Berg
<johannes@sipsolutions.net> wrote:
>
> Hi,
>
> > When I use 2.4Ghz band with -only one- AP (running on top of hostapd)
> > I get a (additional) list of frequencies at 5Ghz. When I do "iw dev ..
> > scan"
> >
> > BSS 02:00:00:00:04:00(on sta1-wlan0) -- associated
> > TSF: 1566905272877856 usec (18135d, 11:27:52)
> > freq: 2422
> > beacon interval: 100 TUs
> > capability: ESS ShortSlotTime (0x0401)
> > signal: -34.00 dBm
> > last seen: 0 ms ago
> > Information elements from Probe Response frame:
> > SSID: simplewifi
> > Supported rates: 1.0* 2.0* 5.5* 11.0* 6.0 9.0 12.0 18.0
> > DS Parameter set: channel 3
> > ERP: Barker_Preamble_Mode
> > Extended supported rates: 24.0 36.0 48.0 54.0
> > Extended capabilities:
> > * Extended Channel Switching
> > * Multiple BSSID
> > * SSID List
> > * Operating Mode Notification
>
> I guess this is the one you expect?
>
> > BSS 02:00:00:00:04:00(on sta1-wlan0)
> > TSF: 1566905274269230 usec (18135d, 11:27:54)
> > freq: 5180
> [...]
> > BSS 02:00:00:00:04:00(on sta1-wlan0)
> > TSF: 1566905274269230 usec (18135d, 11:27:54)
> > freq: 5200
>
> and these are garbage.
>
> > and so on (please notice that channel number and frequency)..
> > iw dev scan returns all the 5Ghz frequencies defined in
> > https://github.com/torvalds/linux/blob/master/drivers/net/wireless/mac80211_hwsim.c#L328
> > It happens only when wmediumd is being used.
>
> Since you cannot reproduce this without wmediumd (and neither can I) I
> assume it's a wmediumd bug, in the sense that it's reporting the frame
> on all the channels, or perhaps without any channel information, or so?
>
> Or possibly the hwsim code that handles this is broken, maybe you could
> see what wmediumd does (does it have any log files?)
>
> johannes
>