> Date: Sat, 8 Oct 2016 13:06:53 +0200 (CEST)
> From: Mark Kettenis <mark.kette...@xs4all.nl>
>
> > Date: Fri, 7 Oct 2016 18:59:52 +0200
> > From: Stefan Sperling <s...@stsp.name>
> >
> > On Fri, Oct 07, 2016 at 03:28:19PM +0200, Stefan Sperling wrote:
> > > Currently tcpdump shows "0 Mbit/s" for any frame sent with 11n HT MCS.
> > > To make progress easier, I'd like to see which MCS are used on the air,
> > > by any device.
> > >
> > > The change below matches what FreeBSD did to pass an MCS index via
> > > radiotap.
> > > This simply writes the MCS index into a previously unused range of rate
> > > values.
> > > This format is already recognized by third party tools such as wireshark
> > > so let's just do it the same way.
> > >
> > > The diff below updates the radiotap docs, makes iwn pass the MCS index,
> > > shows it in tcpdump. I can now see MCS with iwn in monitor mode.
> > >
> > > ok?
> >
> > Same diff, plus iwn now captures MIMO frames in monitor mode.
>
> The addition might need to be tested on a 1TR1 and 2T3R setups. I can
> test the latter, but I have no hardware to test the former.
FWIW, this seems to cause no regressions on:
iwn0 at pci2 dev 0 function 0 "Intel WiFi Link 5300" rev 0x00: msi, MIMO 3T3R,
MoW, address 00:21:6a:13:67:82
Cheers,
Mark
> > Index: sys/net80211/ieee80211_radiotap.h
> > ===================================================================
> > RCS file: /cvs/src/sys/net80211/ieee80211_radiotap.h,v
> > retrieving revision 1.13
> > diff -u -p -r1.13 ieee80211_radiotap.h
> > --- sys/net80211/ieee80211_radiotap.h 12 Jan 2016 09:28:09 -0000
> > 1.13
> > +++ sys/net80211/ieee80211_radiotap.h 7 Oct 2016 13:15:59 -0000
> > @@ -90,9 +90,10 @@ struct ieee80211_radiotap_header {
> > * For frequency-hopping radios, the hop set (first byte)
> > * and pattern (second byte).
> > *
> > - * IEEE80211_RADIOTAP_RATE u_int8_t 500kb/s
> > + * IEEE80211_RADIOTAP_RATE u_int8_t 500kb/s or MCS
> > index
> > *
> > - * Tx/Rx data rate
> > + * Tx/Rx data rate in units of 500kb/s. If the high bit (0x80) is set
> > + * the remaining bits contain an MCS index instead of a date rate.
> > *
> > * IEEE80211_RADIOTAP_DBM_ANTSIGNAL int8_t decibels from
> > * one milliwatt (dBm)
> > Index: sys/dev/pci/if_iwn.c
> > ===================================================================
> > RCS file: /cvs/src/sys/dev/pci/if_iwn.c,v
> > retrieving revision 1.172
> > diff -u -p -r1.172 if_iwn.c
> > --- sys/dev/pci/if_iwn.c 5 Sep 2016 08:18:18 -0000 1.172
> > +++ sys/dev/pci/if_iwn.c 7 Oct 2016 16:33:39 -0000
> > @@ -2131,23 +2131,27 @@ iwn_rx_done(struct iwn_softc *sc, struct
> > tap->wr_dbm_antsignal = (int8_t)rssi;
> > tap->wr_dbm_antnoise = (int8_t)sc->noise;
> > tap->wr_tsft = stat->tstamp;
> > - switch (stat->rate) {
> > - /* CCK rates. */
> > - case 10: tap->wr_rate = 2; break;
> > - case 20: tap->wr_rate = 4; break;
> > - case 55: tap->wr_rate = 11; break;
> > - case 110: tap->wr_rate = 22; break;
> > - /* OFDM rates. */
> > - case 0xd: tap->wr_rate = 12; break;
> > - case 0xf: tap->wr_rate = 18; break;
> > - case 0x5: tap->wr_rate = 24; break;
> > - case 0x7: tap->wr_rate = 36; break;
> > - case 0x9: tap->wr_rate = 48; break;
> > - case 0xb: tap->wr_rate = 72; break;
> > - case 0x1: tap->wr_rate = 96; break;
> > - case 0x3: tap->wr_rate = 108; break;
> > - /* Unknown rate: should not happen. */
> > - default: tap->wr_rate = 0;
> > + if (stat->rflags & IWN_RFLAG_MCS) {
> > + tap->wr_rate = (0x80 | stat->rate); /* HT MCS index */
> > + } else {
> > + switch (stat->rate) {
> > + /* CCK rates. */
> > + case 10: tap->wr_rate = 2; break;
> > + case 20: tap->wr_rate = 4; break;
> > + case 55: tap->wr_rate = 11; break;
> > + case 110: tap->wr_rate = 22; break;
> > + /* OFDM rates. */
> > + case 0xd: tap->wr_rate = 12; break;
> > + case 0xf: tap->wr_rate = 18; break;
> > + case 0x5: tap->wr_rate = 24; break;
> > + case 0x7: tap->wr_rate = 36; break;
> > + case 0x9: tap->wr_rate = 48; break;
> > + case 0xb: tap->wr_rate = 72; break;
> > + case 0x1: tap->wr_rate = 96; break;
> > + case 0x3: tap->wr_rate = 108; break;
> > + /* Unknown rate: should not happen. */
> > + default: tap->wr_rate = 0;
> > + }
> > }
> >
> > mb.m_data = (caddr_t)tap;
> > @@ -2876,8 +2880,7 @@ iwn_tx(struct iwn_softc *sc, struct mbuf
> > if ((ni->ni_flags & IEEE80211_NODE_HT) &&
> > !IEEE80211_IS_MULTICAST(wh->i_addr1) &&
> > type == IEEE80211_FC0_TYPE_DATA) {
> > - /* XXX need a way to pass current MCS in 11n mode */
> > - tap->wt_rate = 0;
> > + tap->wt_rate = (0x80 | ni->ni_txmcs);
> > } else
> > tap->wt_rate = rinfo->rate;
> > tap->wt_hwqueue = ac;
> > @@ -4498,13 +4501,18 @@ iwn_config(struct iwn_softc *sc)
> > sc->rxon.ht_triple_mask = 0xff;
> > rxchain =
> > IWN_RXCHAIN_VALID(sc->rxchainmask) |
> > - IWN_RXCHAIN_MIMO_COUNT(2) |
> > - IWN_RXCHAIN_IDLE_COUNT(2);
> > + IWN_RXCHAIN_MIMO_COUNT(sc->nrxchains) |
> > + IWN_RXCHAIN_IDLE_COUNT(sc->nrxchains);
> > + if (ic->ic_opmode == IEEE80211_M_MONITOR) {
> > + rxchain |= IWN_RXCHAIN_FORCE_SEL(sc->rxchainmask);
> > + rxchain |= IWN_RXCHAIN_FORCE_MIMO_SEL(sc->rxchainmask);
> > + rxchain |= (IWN_RXCHAIN_DRIVER_FORCE | IWN_RXCHAIN_MIMO_FORCE);
> > + }
> > sc->rxon.rxchain = htole16(rxchain);
> > DPRINTF(("setting configuration\n"));
> > - DPRINTF(("%s: rxon chan %d flags %x cck %x ofdm %x\n", __func__,
> > - sc->rxon.chan, le32toh(sc->rxon.flags), sc->rxon.cck_mask,
> > - sc->rxon.ofdm_mask));
> > + DPRINTF(("%s: rxon chan %d flags %x cck %x ofdm %x rxchain %x\n",
> > + __func__, sc->rxon.chan, le32toh(sc->rxon.flags), sc->rxon.cck_mask,
> > + sc->rxon.ofdm_mask, sc->rxon.rxchain));
> > error = iwn_cmd(sc, IWN_CMD_RXON, &sc->rxon, sc->rxonsz, 0);
> > if (error != 0) {
> > printf("%s: RXON command failed\n", sc->sc_dev.dv_xname);
> > Index: usr.sbin/tcpdump/print-802_11.c
> > ===================================================================
> > RCS file: /cvs/src/usr.sbin/tcpdump/print-802_11.c,v
> > retrieving revision 1.33
> > diff -u -p -r1.33 print-802_11.c
> > --- usr.sbin/tcpdump/print-802_11.c 2 Sep 2016 17:11:46 -0000 1.33
> > +++ usr.sbin/tcpdump/print-802_11.c 7 Oct 2016 12:44:25 -0000
> > @@ -1075,8 +1075,13 @@ ieee802_11_radio_if_print(u_char *user,
> >
> > if (RADIOTAP(RATE)) {
> > TCHECK2(*t, 1);
> > - if (vflag)
> > - printf(", %uMbit/s", (*(u_int8_t*)t) / 2);
> > + if (vflag) {
> > + uint8_t rate = *(u_int8_t*)t;
> > + if (rate & 0x80)
> > + printf(", MCS %u", rate & 0x7f);
> > + else
> > + printf(", %uMbit/s", rate / 2);
> > + }
> > t += 1;
> > }
> >
> >
> >
>
>
