Hello,
I'm trying to disable MAC layer ACKs for some testing I'm doing. I can't
seem to pin down the best way to do this, though.
From some mailing list posts it seems I should be able to set the NoAck
flag on any frames I send from a fairly high level of the networking
stack. I can't seem to figure out where I'd do this, or what interface I
should be using to do so - sockets don't know anything about MAC layers,
and that's as low as I know how to go in userspace.
Coming at it from the other side, I found mac80211_tx_control_flags has
a field called IEEE80211_TX_CTL_NO_ACK, which one could presumably set
to achieve this effect. However my (admittedly limited) understanding is
that mac80211 is at the driver level, or at least not in userspace, so I
don't know where/when this would get set.
I was hoping that iw's noack_map command would work for me, although I
didn't really understand what a TID meant in this context, but when I
try to run it I get "command failed: Operation not supported (-95)". I
suppose it's possible my hardware just doesn't support 802.11e, but as
far as I can tell it does. Is that the only reason one should expect to
see that error? Is it possibly related to the fact that I had to compile
iw 3.3 myself on Ubuntu 12.04, which ships with 3.2 which doesn't have
noack_map, and I didn't upgrade any libraries or anything when I did so?
Finally, I noted from a mailing list post from 2011 that this can be
done for Atheros chips (which this is) by adding REG_SET_BIT(ah,
AR_DIAG_SW, AR_DIAG_ACK_DIS) into the ath5k/9k code. I suppose I could
do this, but I'd be glad to avoid a custom driver if at all possible.
Can anyone point me in the right direction?
Thanks,
~Andrew Wygle
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