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Subject: Re: Why "iwlwifi: read multiple MAC addresses"?
From: Johannes Berg <johannes@sipsolutions.net>
To: Lekensteyn <lekensteyn@gmail.com>
Cc: Wey-Yi Guy <wey-yi.w.guy@intel.com>,
	Intel Linux Wireless <ilw@linux.intel.com>,
	linux-wireless@vger.kernel.org
Date: Tue, 12 Jun 2012 21:58:51 +0200
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On Tue, 2012-06-12 at 15:11 +0200, Lekensteyn wrote:

> I wonder what the following commit is used for:
> commit c6fa17ed3fadaf056173c409c0877df428a152ec
> Author: Wey-Yi Guy <wey-yi.w.guy@intel.com>
> Date:   Thu Jul 15 05:58:30 2010 -0700
> 
>     iwlwifi: read multiple MAC addresses

That commit is so that you see this:

> I was trying to debug wireless issues, and noticed that I had two MAC 
> addresses with only the last bit being different:
> 
>     $ cat /sys/class/ieee80211/phy0/addresses
>     00:23:14:xx:xx:x8
>     00:23:14:xx:xx:x9
> 
> Looking at a dump provided by /sys/kernel/debug/cfg80211/phy0/iwlwifi/data/nvm, 
> I see that the 16-bit word at 0x98 contains the value 4. What does this mean? 

The 4 actually means that there are 4 addresses assigned to this device,
for use in P2P scenarios etc. We only support 2 virtual interfaces in
Linux today, so we don't expose 4 (though we probably could.)

> Can this break something?

No.

johannes