Question: ath10k and tcpdump antenna noise information missing
Tomi Saarnio
Tomi.Saarnio at ekahau.com
Thu Nov 5 05:38:17 PST 2015
Hi All,
After some digging, I found this piece of code in Linux kernel 4.1 file
net/mac80211/rx.c in function ieee80211_add_rx_radiotap_header:
...
/* IEEE80211_RADIOTAP_DBM_ANTSIGNAL */
if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM &&
!(status->flag & RX_FLAG_NO_SIGNAL_VAL)) {
*pos = status->signal;
rthdr->it_present |=
cpu_to_le32(1 << IEEE80211_RADIOTAP_DBM_ANTSIGNAL);
pos++;
}
/* IEEE80211_RADIOTAP_LOCK_QUALITY is missing */
if (!status->chains) {
/* IEEE80211_RADIOTAP_ANTENNA */
*pos = status->antenna;
pos++;
}
/* IEEE80211_RADIOTAP_DB_ANTNOISE is not used */
/* IEEE80211_RADIOTAP_RX_FLAGS */
/* ensure 2 byte alignment for the 2 byte field as required */
...
The comment /* IEEE80211_RADIOTAP_DB_ANTNOISE is not used */ tells quite
clearly why the antenna noise information is not be available in the radiotap and tcpdump.
Clearly this is not a driver issue any more, but a network layer issue. I will try to look
a solution elsewhere how to get the antenna noise information into userspace in a proper way.
Best regards,
Tomi Saarnio
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