Hi Daniel,
I am using the same card and the ath9k driver. I was also not able to
receive frames with CRC errors by setting the fcsfail flag while
creating the monitor mode interface. I looked up the code and found
that ath9k ignores frames with CRC errors in monitor mode.
The ath9k_rx_accept function in common.c has the following condition
if (ah->opmode == NL80211_IFTYPE_MONITOR) {
if (rx_stats->rs_status &
~(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_MIC |
ATH9K_RXERR_CRC))
return false;
Clearly, this function will return false in case of a CRC error while
receiving on a monitor interface.
For your info, this function is called by ath9k_rx_skb_preprocess
which in turn is invoked in ath9k_rx_tasklet.
In order to receive frames with CRC errors in monitor mode, I just
removed ATH9K_RXERR_CRC from the above snippet, recompiled and
reloaded ath9k and was able to receive frames with CRC errors.
I hope that helps.
-Qasim
On Thu, Aug 5, 2010 at 9:14 AM, Daniel Haid <d.haid@xxxxxxx> wrote:
>
> Hello,
>
> is it possible to receive packets with bad FCS in monitor mode (ath9k driver)?
> There is a comment in ath9k/common.c which says that a bad checksum is
> ignored in monitor mode, but I have so far never been able to receive a
> packet with bad FCS (I do not know how to generate such packets,
> so I might just be too lucky that all packets are received unimpaired).
>
> Does ath9k hardware drop packets with bad FCS directly? If so, can
> it be disabled?
>
> Best regards.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
