Re: [RFC] change mac80211_hwsim tx_rates to ieee80211_tx_rate

[Johannes Berg <johannes@sipsolutions.net>]

> Mhh, I thought also some atheros drivers implement hardware multirate
> retry changes, which maps to this struct. Only one rate per frame
> would introduce a extreme additional communication overhead, which
> will make testing with standard wmediumd impractical. I think we need
> to keep such a structure, but we should align that with other
> mac80211 depended drivers.

Yeah, I was being imprecise. The driver interface is usually similar to
the mac80211 struct in one way or another (though it might also be a
more global table, like other drivers implement).

I was more thinking of the actual air interface. I'm not too worried
about the efficiency of this (we can push quite a few gbps over hwsim
today iirc), but it actually doesn't make sense because an accurate
simulation would require NAV/TXOP simulation, and that wouldn't be
possible with "software retry".

So I think our best bet remains to map this to new attributes - better
with properly formatted ones etc. than with the struct (keeping that
only for compatibility)

If you're worried about the overhead, we could consider converting
hwsim to use the rate_table API - see struct ieee80211_sta -> rates,
and maybe adding a signal to update that in the driver, send that to
userspace directly and work with that, rather than "serializing" the
table for every frame?

johannes