On Feb 18, 2009, at 12:23 AM, Michael Buesch wrote:

> On Wednesday 18 February 2009 00:07:56 Bo Han wrote:
>> I think I am working on the first sanity check in the driver, but  
>> still
>> cannot see any FCS error frames.  Is setting B43_MACCTL_KEEP_BAD  
>> the only
>> thing we need to do for the firmware?
>
> No. I suggest you don't touch that flag anyway and change the  
> corresponding
> mac80211 filter flag. You most likely can do that through cfg80211/ 
> nl80211/iw.
> It will take care to set the b43 flag.

Michael is right, the new iw interface eases all this stuff.

There are however a few points that should be discussed

- why b43_rx(...) (in xmit.c) does not mark the status with  
RX_FLAG_FAILED_FCS_CRC when the firmware reports a B43_RX_MAC_FCSERR:  
IMHO this should be done to prevent mac80211 to be corrupted and crash  
the pc when a _very_ noisy frame arrives

- is that correct to have status.rate_idx filled by functions  
b43_plcp_get_bitrate_idx_ofdm and b43_plcp_get_bitrate_idx_cck that  
compute those values reading the plcp? When a frame is ok, values are  
correct and mac80211 uses them without problems. If instead the frame  
is not ok, then mac80211 can warn a lot of message because values are  
out of range. Should not we parse these values when FCS is bad and  
sanitize them if out of range so that dmesg does not get filled with  
warnings? Or probably there is another method to get those values,  
e.g., the firmware can provide them reading from the radio instead of  
computing them reading fields from the plcp?

- I noticed that when in monitor mode and when set up to keep bad  
frames, the radiotap header is not reporting FCS wrong for malformed  
or corrupted frame as it should be, is that correct? Should not the  
radiotap header be built on the status filled by first the driver then  
mac80211?

Cheers,
-FG



>
>
> -- 
> Greetings, Michael.
> _______________________________________________
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-------

Francesco Gringoli, PhD - Assistant Professor
Dept. of Electrical Engineering for Automation
University of Brescia
via Branze, 38
25123 Brescia
ITALY

Ph:  ++39.030.3715843
FAX: ++39.030.380014
WWW: http://www.ing.unibs.it/~gringoli




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