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Subject: Re: 31-rc3-mmotm0716 - wonky wireless statistics..
From: Zhu Yi <yi.zhu@intel.com>
To: "Valdis.Kletnieks@vt.edu" <Valdis.Kletnieks@vt.edu>,
	Johannes Berg <johannes@sipsolutions.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
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Date: Wed, 29 Jul 2009 09:31:18 +0800
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On Wed, 2009-07-29 at 05:01 +0800, Valdis.Kletnieks@vt.edu wrote:
> Dell Latitude D820 laptop, lspci reports the network card as:
> 
> 0c:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Netwo           rk Connection (rev 02)
> 
> iwlwifi driver in use, card associated via wpa_supplicant but not being
> actively used
> 
> # iwconfig
> wlan0     IEEE 802.11abg  ESSID:"VT-Wireless"  
>           Mode:Managed  Frequency:2.447 GHz  Access Point: 00:11:20:A4:4C:10   
>           Bit Rate=54 Mb/s   Tx-Power=15 dBm   
>           Retry  long limit:7   RTS thr:off   Fragment thr:off
>           Encryption key:<lopped out> [2]
>           Link Quality=62/70  Signal level=-48 dBm  
>           Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
>           Tx excessive retries:0  Invalid misc:0   Missed beacon:0
> # cat /proc/net/wireless
> Inter-| sta-|   Quality        |   Discarded packets               | Missed | WE
>  face | tus | link level noise |  nwid  crypt   frag  retry   misc | beacon | 22
>  wlan0: 0000   63.  -47.  -256        0      0      0      0      0        0
>  wlan1: 0000    0     0     0        0      0      0      0      0        0
>  wlan2: 0000    0     0     0        0      0      0      0      0        0
> 
> Where did that -256 for "noise" come from?  It ends up confusing the
> gkrellm-wifi plugin, it reports a S/N of 219dB ;)

This should be related to http://git.kernel.org/?p=linux/kernel/git/linville/wireless-testing.git;a=commit;h=fdb897ea5c77836f890033d563336ab0c94c9222

But I don't think this is an ABI broken. User space should parse the
trailing '.' to see if a field is updated or not because there are cards
not capable to report hardware noise level anyway. Johannes?

Thanks,
-yi