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Re: [PATCH V3 0/2] brcmfmac: initial work for adding monitor mode

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On 2018-06-25 10:28, Arend van Spriel wrote:
On 6/24/2018 4:20 PM, Rafał Miłecki wrote:
On Fri, 22 Jun 2018 at 20:59, Arend van Spriel
<arend.vanspriel@xxxxxxxxxxxx> wrote:
On 6/19/2018 10:25 PM, Rafał Miłecki wrote:
On 2018-06-19 22:01, Arend van Spriel wrote:
On 6/19/2018 5:48 PM, Rafał Miłecki wrote:
From: Rafał Miłecki <rafal@xxxxxxxxxx>

After a bit long discussions in various e-mail threads I'm coming with this simple & small patchset. It isn't complete support for monitor mode
but just a pair of preparing patches that should be clear & well
discussed by now to make them acceptable.

The main missing bit is code setting MONITOR_FMT_RADIOTAP which I expect Arend to handle soon, as he already has a patch using "sta_monitor" iovar for that. Then we have to discuss a flag for marking firmwares
which are capable for tagging monitor frames.

While still incomplete, I believe that with my previous patches, we can
agree this is a good direction.

Arend: if you find these 2 patches OK, could you ack them, to make it clear for Kalle if they look OK now (or not yet)? I'd be great if you
could sent your "sta_monitor" work on top of this.

I acked them and I will submit my changes later. Either after these
are applied or simply indicate the dependency.

Now as for where we are with this. With what we have here we know
firmware can monitor packets with and without radiotap. However, we do
not have an indication whether firmware can transport these monitor
packets to the host. What I need to look into next is whether the
802.11 flag in msgbuf is linked to a particular version of the
protocol, but we may need to resort to the fwid table.

Being able to detect if firmware tags monitor packets would be great.

The 802.11 tag as opposed the 802.3 tag is specified in the PCIe host
interface spec. The brcmfmac driver support rev 5 and 6 of that spec and
both specify the tags. I did some digging and I believe it is safe to
say that firmware that includes the "monitor" tag in the "cap" iovar
does support these packets tags as well.

OK, this is nice. The problem is we still need some fallback for the
old firmwares. Only the newest ones specify "monitor" tag in the "cap"
iovar. Older firmwares don't specify it but they still may include
support for monitor mode and radiotap header.

So in your list of firmwares, do you know (or can you find out :-p )
which ones return "monitor" and which do not? My educated guess was
that only firmwares returning "monitor" tag have host-interface code
in place to send monitor packets up to the host. You may prove me
wrong.

None of my firmwares have "monitor" flag in the "cap" iovar. This seems
to be something really new. I'm still looking for some firmware new
enough to report "monitor" flag. Unfortunately most vendors seem to be
using 10.10.69.* or 10.10.122.20 which aren't new enough for that.



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