WRT54g / b43 / mac802.11 BREAKTHROUGH

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Hauke Mehrtens]

On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
> hi devs!
> 
> yesterday we had a breaktrough debugging b43 in our hackspace maschinenraum/m18[1,2]
> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g suffers from a
> hanging wifi and bad performance[5], but the workaround is easy: now it's up to
> you to fix the rootcause.
> 
> our testsetup, where we could _reproduce_ reliably a stopping TX is like this:
> 
> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
> 
> now make a testdownload with the laptop from B.
> wireless will stop working after ~10 seconds.
> 
> wifi up will reanimate and our freifunk-cron.minutely-check
> will do this automagically. (read further, this is not the solution)
> 
> we tried to limit the rateset to e.g. lower rates, but this does NOT change
> the behaviour. what works is: define a rateset on BOTH router which makes
> it impossible to change the band, e.g.:
> 
> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
> OR
> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
> 
> now we had a great performance, 10 Gigabytes of wireless transfer,
> no stopping TX anymore and an empty box of beer. three things to do now:
> 
> 1) why does a band change (can be seen through minstrel) is a problem?
> 
> 2) we have to make in config-option to force a band, or a rateset:
> 	e.g. uci set wireless.radio0.hwmode=11g
> 	e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
> 
> 3) spread to word:
>    there is a great frustration in the community about b43,
>    but the old drivers _have_ to die, it's about time - really.
> 
> thanks for your work,
> bye storchi, andi, bastian + m18 crew
> 
> [1] http://blog.maschinenraum.tk/
> [2] http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
> [3] http://wireless.subsignal.org
> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
> [5] https://dev.openwrt.org/ticket/7552

I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
it is easily reproducible on all tested devices when restricting the
rates to 11 and 12 MBit/s.

I have the Broadcom device working as an Access point (on a MIPS SoC)
and a Laptop with an Intel Wifi device is connected to it. I generated
the traffic with iperf. If the Access Points sends the traffic the
problem occurs, if it is just receiving there is not problem.

After the problem occurred b43_generate_txhdr is called rarely ( every
~10 seconds) and I am not able to stay connected or connect to the
network any more. I am not familiar with the internal flow in b43 or
mac80211 could someone give me a hint where to look.

I can not see any special changes between CCK and OFDM rates before it
goes down there are many changes without a problem before it goes down.

Currently I do not have a Broadcom wifi card running in a x86 device
just mips devices could someone try to reproduce the problem on a x86
device.

I added the b43 mailing list and Rafa?.

Hauke

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Rafał Miłecki]

2012/8/22 Hauke Mehrtens <hauke@hauke-m.de>:
> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>> hi devs!
>>
>> yesterday we had a breaktrough debugging b43 in our hackspace maschinenraum/m18[1,2]
>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g suffers from a
>> hanging wifi and bad performance[5], but the workaround is easy: now it's up to
>> you to fix the rootcause.
>>
>> our testsetup, where we could _reproduce_ reliably a stopping TX is like this:
>>
>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>
>> now make a testdownload with the laptop from B.
>> wireless will stop working after ~10 seconds.
>>
>> wifi up will reanimate and our freifunk-cron.minutely-check
>> will do this automagically. (read further, this is not the solution)
>>
>> we tried to limit the rateset to e.g. lower rates, but this does NOT change
>> the behaviour. what works is: define a rateset on BOTH router which makes
>> it impossible to change the band, e.g.:
>>
>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>> OR
>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>
>> now we had a great performance, 10 Gigabytes of wireless transfer,
>> no stopping TX anymore and an empty box of beer. three things to do now:
>>
>> 1) why does a band change (can be seen through minstrel) is a problem?
>>
>> 2) we have to make in config-option to force a band, or a rateset:
>>       e.g. uci set wireless.radio0.hwmode=11g
>>       e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>
>> 3) spread to word:
>>    there is a great frustration in the community about b43,
>>    but the old drivers _have_ to die, it's about time - really.
>>
>> thanks for your work,
>> bye storchi, andi, bastian + m18 crew
>>
>> [1] http://blog.maschinenraum.tk/
>> [2] http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>> [3] http://wireless.subsignal.org
>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>> [5] https://dev.openwrt.org/ticket/7552
>
> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
> it is easily reproducible on all tested devices when restricting the
> rates to 11 and 12 MBit/s.
>
> I have the Broadcom device working as an Access point (on a MIPS SoC)
> and a Laptop with an Intel Wifi device is connected to it. I generated
> the traffic with iperf. If the Access Points sends the traffic the
> problem occurs, if it is just receiving there is not problem.
>
> After the problem occurred b43_generate_txhdr is called rarely ( every
> ~10 seconds) and I am not able to stay connected or connect to the
> network any more. I am not familiar with the internal flow in b43 or
> mac80211 could someone give me a hint where to look.
>
> I can not see any special changes between CCK and OFDM rates before it
> goes down there are many changes without a problem before it goes down.
>
> Currently I do not have a Broadcom wifi card running in a x86 device
> just mips devices could someone try to reproduce the problem on a x86
> device.
>
> I added the b43 mailing list and Rafa?.

Does your kernel include

commit bad6919469662b7c92bc6353642aaaa777b36bac
Author: francesco.gringoli at ing.unibs.it <francesco.gringoli@ing.unibs.it>
Date:   Fri Dec 16 18:34:56 2011 +0100

    b43: avoid packet losses in the dma worker code.

? I have a lot of things on my TODO list, including that. Right now I
just want to focus on BCM4706 support, which slowly moves into
mainline.

-- 
Rafa?

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Hauke Mehrtens]

On 08/22/2012 07:49 PM, Rafa? Mi?ecki wrote:
> 2012/8/22 Hauke Mehrtens <hauke@hauke-m.de>:
>> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>>> hi devs!
>>>
>>> yesterday we had a breaktrough debugging b43 in our hackspace maschinenraum/m18[1,2]
>>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g suffers from a
>>> hanging wifi and bad performance[5], but the workaround is easy: now it's up to
>>> you to fix the rootcause.
>>>
>>> our testsetup, where we could _reproduce_ reliably a stopping TX is like this:
>>>
>>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>>
>>> now make a testdownload with the laptop from B.
>>> wireless will stop working after ~10 seconds.
>>>
>>> wifi up will reanimate and our freifunk-cron.minutely-check
>>> will do this automagically. (read further, this is not the solution)
>>>
>>> we tried to limit the rateset to e.g. lower rates, but this does NOT change
>>> the behaviour. what works is: define a rateset on BOTH router which makes
>>> it impossible to change the band, e.g.:
>>>
>>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>>> OR
>>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>>
>>> now we had a great performance, 10 Gigabytes of wireless transfer,
>>> no stopping TX anymore and an empty box of beer. three things to do now:
>>>
>>> 1) why does a band change (can be seen through minstrel) is a problem?
>>>
>>> 2) we have to make in config-option to force a band, or a rateset:
>>>       e.g. uci set wireless.radio0.hwmode=11g
>>>       e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>>
>>> 3) spread to word:
>>>    there is a great frustration in the community about b43,
>>>    but the old drivers _have_ to die, it's about time - really.
>>>
>>> thanks for your work,
>>> bye storchi, andi, bastian + m18 crew
>>>
>>> [1] http://blog.maschinenraum.tk/
>>> [2] http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>>> [3] http://wireless.subsignal.org
>>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>>> [5] https://dev.openwrt.org/ticket/7552
>>
>> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
>> it is easily reproducible on all tested devices when restricting the
>> rates to 11 and 12 MBit/s.
>>
>> I have the Broadcom device working as an Access point (on a MIPS SoC)
>> and a Laptop with an Intel Wifi device is connected to it. I generated
>> the traffic with iperf. If the Access Points sends the traffic the
>> problem occurs, if it is just receiving there is not problem.
>>
>> After the problem occurred b43_generate_txhdr is called rarely ( every
>> ~10 seconds) and I am not able to stay connected or connect to the
>> network any more. I am not familiar with the internal flow in b43 or
>> mac80211 could someone give me a hint where to look.
>>
>> I can not see any special changes between CCK and OFDM rates before it
>> goes down there are many changes without a problem before it goes down.
>>
>> Currently I do not have a Broadcom wifi card running in a x86 device
>> just mips devices could someone try to reproduce the problem on a x86
>> device.
>>
>> I added the b43 mailing list and Rafa?.
> 
> Does your kernel include
> 
> commit bad6919469662b7c92bc6353642aaaa777b36bac
> Author: francesco.gringoli at ing.unibs.it <francesco.gringoli@ing.unibs.it>
> Date:   Fri Dec 16 18:34:56 2011 +0100
> 
>     b43: avoid packet losses in the dma worker code.
> 
> ? I have a lot of things on my TODO list, including that. Right now I
> just want to focus on BCM4706 support, which slowly moves into
> mainline.
> 

This patch is included. I used compat-wireless-2012-07-16 plus some more
backport patches for b43.

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Larry Finger]

On 08/22/2012 11:21 AM, Hauke Mehrtens wrote:
> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>> hi devs!
>>
>> yesterday we had a breaktrough debugging b43 in our hackspace maschinenraum/m18[1,2]
>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g suffers from a
>> hanging wifi and bad performance[5], but the workaround is easy: now it's up to
>> you to fix the rootcause.
>>
>> our testsetup, where we could _reproduce_ reliably a stopping TX is like this:
>>
>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>
>> now make a testdownload with the laptop from B.
>> wireless will stop working after ~10 seconds.
>>
>> wifi up will reanimate and our freifunk-cron.minutely-check
>> will do this automagically. (read further, this is not the solution)
>>
>> we tried to limit the rateset to e.g. lower rates, but this does NOT change
>> the behaviour. what works is: define a rateset on BOTH router which makes
>> it impossible to change the band, e.g.:
>>
>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>> OR
>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>
>> now we had a great performance, 10 Gigabytes of wireless transfer,
>> no stopping TX anymore and an empty box of beer. three things to do now:
>>
>> 1) why does a band change (can be seen through minstrel) is a problem?
>>
>> 2) we have to make in config-option to force a band, or a rateset:
>> 	e.g. uci set wireless.radio0.hwmode=11g
>> 	e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>
>> 3) spread to word:
>>     there is a great frustration in the community about b43,
>>     but the old drivers _have_ to die, it's about time - really.
>>
>> thanks for your work,
>> bye storchi, andi, bastian + m18 crew
>>
>> [1] http://blog.maschinenraum.tk/
>> [2] http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>> [3] http://wireless.subsignal.org
>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>> [5] https://dev.openwrt.org/ticket/7552
>
> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
> it is easily reproducible on all tested devices when restricting the
> rates to 11 and 12 MBit/s.
>
> I have the Broadcom device working as an Access point (on a MIPS SoC)
> and a Laptop with an Intel Wifi device is connected to it. I generated
> the traffic with iperf. If the Access Points sends the traffic the
> problem occurs, if it is just receiving there is not problem.
>
> After the problem occurred b43_generate_txhdr is called rarely ( every
> ~10 seconds) and I am not able to stay connected or connect to the
> network any more. I am not familiar with the internal flow in b43 or
> mac80211 could someone give me a hint where to look.
>
> I can not see any special changes between CCK and OFDM rates before it
> goes down there are many changes without a problem before it goes down.
>
> Currently I do not have a Broadcom wifi card running in a x86 device
> just mips devices could someone try to reproduce the problem on a x86
> device.
>
> I added the b43 mailing list and Rafa?.

Hauke or Bastian,

Do you have any info whether the failure occurs with the change from OFDM to 
CCK, or vice versa? I am wondering if the radio needs a dummy transmission when 
the switch happens. I will try to put together a patch to test that hypothesis.

Larry

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Hauke Mehrtens]

On 08/22/2012 08:45 PM, Larry Finger wrote:
> On 08/22/2012 11:21 AM, Hauke Mehrtens wrote:
>> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>>> hi devs!
>>>
>>> yesterday we had a breaktrough debugging b43 in our hackspace
>>> maschinenraum/m18[1,2]
>>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g
>>> suffers from a
>>> hanging wifi and bad performance[5], but the workaround is easy: now
>>> it's up to
>>> you to fix the rootcause.
>>>
>>> our testsetup, where we could _reproduce_ reliably a stopping TX is
>>> like this:
>>>
>>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>>
>>> now make a testdownload with the laptop from B.
>>> wireless will stop working after ~10 seconds.
>>>
>>> wifi up will reanimate and our freifunk-cron.minutely-check
>>> will do this automagically. (read further, this is not the solution)
>>>
>>> we tried to limit the rateset to e.g. lower rates, but this does NOT
>>> change
>>> the behaviour. what works is: define a rateset on BOTH router which
>>> makes
>>> it impossible to change the band, e.g.:
>>>
>>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>>> OR
>>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>>
>>> now we had a great performance, 10 Gigabytes of wireless transfer,
>>> no stopping TX anymore and an empty box of beer. three things to do now:
>>>
>>> 1) why does a band change (can be seen through minstrel) is a problem?
>>>
>>> 2) we have to make in config-option to force a band, or a rateset:
>>>     e.g. uci set wireless.radio0.hwmode=11g
>>>     e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>>
>>> 3) spread to word:
>>>     there is a great frustration in the community about b43,
>>>     but the old drivers _have_ to die, it's about time - really.
>>>
>>> thanks for your work,
>>> bye storchi, andi, bastian + m18 crew
>>>
>>> [1] http://blog.maschinenraum.tk/
>>> [2]
>>> http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>>>
>>> [3] http://wireless.subsignal.org
>>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>>> [5] https://dev.openwrt.org/ticket/7552
>>
>> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
>> it is easily reproducible on all tested devices when restricting the
>> rates to 11 and 12 MBit/s.
>>
>> I have the Broadcom device working as an Access point (on a MIPS SoC)
>> and a Laptop with an Intel Wifi device is connected to it. I generated
>> the traffic with iperf. If the Access Points sends the traffic the
>> problem occurs, if it is just receiving there is not problem.
>>
>> After the problem occurred b43_generate_txhdr is called rarely ( every
>> ~10 seconds) and I am not able to stay connected or connect to the
>> network any more. I am not familiar with the internal flow in b43 or
>> mac80211 could someone give me a hint where to look.
>>
>> I can not see any special changes between CCK and OFDM rates before it
>> goes down there are many changes without a problem before it goes down.
>>
>> Currently I do not have a Broadcom wifi card running in a x86 device
>> just mips devices could someone try to reproduce the problem on a x86
>> device.
>>
>> I added the b43 mailing list and Rafa?.
> 
> Hauke or Bastian,
> 
> Do you have any info whether the failure occurs with the change from
> OFDM to CCK, or vice versa? I am wondering if the radio needs a dummy
> transmission when the switch happens. I will try to put together a patch
> to test that hypothesis.
> 
> Larry

It is strange. The stop does not occur directly after changing from OFDM
to CCK or vice versa. TX seams to still work, but the device does not
receive anything any more.

Here are some logs from my device:
http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.txt
Patch used:
http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.patch

"iw dev wlan0 set bitrates legacy-2.4 11 12" was issued at ~120.000000.

How do I monitor this particular channel with an other wifi card to get
most of the packages, with aircrack I am unable to set the channel?

Hauke

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Larry Finger]

On 08/22/2012 04:05 PM, Hauke Mehrtens wrote:
> On 08/22/2012 08:45 PM, Larry Finger wrote:
>> On 08/22/2012 11:21 AM, Hauke Mehrtens wrote:
>>> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>>>> hi devs!
>>>>
>>>> yesterday we had a breaktrough debugging b43 in our hackspace
>>>> maschinenraum/m18[1,2]
>>>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g
>>>> suffers from a
>>>> hanging wifi and bad performance[5], but the workaround is easy: now
>>>> it's up to
>>>> you to fix the rootcause.
>>>>
>>>> our testsetup, where we could _reproduce_ reliably a stopping TX is
>>>> like this:
>>>>
>>>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>>>
>>>> now make a testdownload with the laptop from B.
>>>> wireless will stop working after ~10 seconds.
>>>>
>>>> wifi up will reanimate and our freifunk-cron.minutely-check
>>>> will do this automagically. (read further, this is not the solution)
>>>>
>>>> we tried to limit the rateset to e.g. lower rates, but this does NOT
>>>> change
>>>> the behaviour. what works is: define a rateset on BOTH router which
>>>> makes
>>>> it impossible to change the band, e.g.:
>>>>
>>>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>>>> OR
>>>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>>>
>>>> now we had a great performance, 10 Gigabytes of wireless transfer,
>>>> no stopping TX anymore and an empty box of beer. three things to do now:
>>>>
>>>> 1) why does a band change (can be seen through minstrel) is a problem?
>>>>
>>>> 2) we have to make in config-option to force a band, or a rateset:
>>>>      e.g. uci set wireless.radio0.hwmode=11g
>>>>      e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>>>
>>>> 3) spread to word:
>>>>      there is a great frustration in the community about b43,
>>>>      but the old drivers _have_ to die, it's about time - really.
>>>>
>>>> thanks for your work,
>>>> bye storchi, andi, bastian + m18 crew
>>>>
>>>> [1] http://blog.maschinenraum.tk/
>>>> [2]
>>>> http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>>>>
>>>> [3] http://wireless.subsignal.org
>>>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>>>> [5] https://dev.openwrt.org/ticket/7552
>>>
>>> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY) and
>>> it is easily reproducible on all tested devices when restricting the
>>> rates to 11 and 12 MBit/s.
>>>
>>> I have the Broadcom device working as an Access point (on a MIPS SoC)
>>> and a Laptop with an Intel Wifi device is connected to it. I generated
>>> the traffic with iperf. If the Access Points sends the traffic the
>>> problem occurs, if it is just receiving there is not problem.
>>>
>>> After the problem occurred b43_generate_txhdr is called rarely ( every
>>> ~10 seconds) and I am not able to stay connected or connect to the
>>> network any more. I am not familiar with the internal flow in b43 or
>>> mac80211 could someone give me a hint where to look.
>>>
>>> I can not see any special changes between CCK and OFDM rates before it
>>> goes down there are many changes without a problem before it goes down.
>>>
>>> Currently I do not have a Broadcom wifi card running in a x86 device
>>> just mips devices could someone try to reproduce the problem on a x86
>>> device.
>>>
>>> I added the b43 mailing list and Rafa?.
>>
>> Hauke or Bastian,
>>
>> Do you have any info whether the failure occurs with the change from
>> OFDM to CCK, or vice versa? I am wondering if the radio needs a dummy
>> transmission when the switch happens. I will try to put together a patch
>> to test that hypothesis.
>>
>> Larry
>
> It is strange. The stop does not occur directly after changing from OFDM
> to CCK or vice versa. TX seams to still work, but the device does not
> receive anything any more.
>
> Here are some logs from my device:
> http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.txt
> Patch used:
> http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.patch
>
> "iw dev wlan0 set bitrates legacy-2.4 11 12" was issued at ~120.000000.
>
> How do I monitor this particular channel with an other wifi card to get
> most of the packages, with aircrack I am unable to set the channel?

Thanks for the log and the patch you used.

You should be able to use Kismet and set the channel; however, I usually let it 
capture everything, and then use wireshark to analyze the pcap file. That way, 
it is fairly easy to set filters to exclude the unwanted traffic from other AP 
and STA sources.

I don't use wireshark to capture the data because the box I use does not have a 
GUI desktop, and the command-line kismet is perfect for that setup.

Larry

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Hauke Mehrtens]

On 08/22/2012 11:19 PM, Larry Finger wrote:
> On 08/22/2012 04:05 PM, Hauke Mehrtens wrote:
>> On 08/22/2012 08:45 PM, Larry Finger wrote:
>>> On 08/22/2012 11:21 AM, Hauke Mehrtens wrote:
>>>> On 07/18/2012 01:56 PM, Bastian Bittorf wrote:
>>>>> hi devs!
>>>>>
>>>>> yesterday we had a breaktrough debugging b43 in our hackspace
>>>>> maschinenraum/m18[1,2]
>>>>> at weimar.freifunk.net[3,4] - since a long time our darling wrt54g
>>>>> suffers from a
>>>>> hanging wifi and bad performance[5], but the workaround is easy: now
>>>>> it's up to
>>>>> you to fix the rootcause.
>>>>>
>>>>> our testsetup, where we could _reproduce_ reliably a stopping TX is
>>>>> like this:
>>>>>
>>>>> laptop ---lan--- "A"-wrt54g/adhoc ~~~   air  ~~~ "B"-anyrouter/adhoc
>>>>>
>>>>> now make a testdownload with the laptop from B.
>>>>> wireless will stop working after ~10 seconds.
>>>>>
>>>>> wifi up will reanimate and our freifunk-cron.minutely-check
>>>>> will do this automagically. (read further, this is not the solution)
>>>>>
>>>>> we tried to limit the rateset to e.g. lower rates, but this does NOT
>>>>> change
>>>>> the behaviour. what works is: define a rateset on BOTH router which
>>>>> makes
>>>>> it impossible to change the band, e.g.:
>>>>>
>>>>> iw dev $WIFIDEV set bitrates legacy-2.4 1 2 5.5 11
>>>>> OR
>>>>> iw dev $WIFIDEV set bitrates legacy-2.4 6 9 12 18 24 36 48 54
>>>>>
>>>>> now we had a great performance, 10 Gigabytes of wireless transfer,
>>>>> no stopping TX anymore and an empty box of beer. three things to do
>>>>> now:
>>>>>
>>>>> 1) why does a band change (can be seen through minstrel) is a problem?
>>>>>
>>>>> 2) we have to make in config-option to force a band, or a rateset:
>>>>>      e.g. uci set wireless.radio0.hwmode=11g
>>>>>      e.g. uci set wireless.radio0.bitrates='6 9 12 18 24 36 48 54'
>>>>>
>>>>> 3) spread to word:
>>>>>      there is a great frustration in the community about b43,
>>>>>      but the old drivers _have_ to die, it's about time - really.
>>>>>
>>>>> thanks for your work,
>>>>> bye storchi, andi, bastian + m18 crew
>>>>>
>>>>> [1] http://blog.maschinenraum.tk/
>>>>> [2]
>>>>> http://blog.maschinenraum.tk/2012/07/15/bitcoin-vending-machine-exchange-euro-coins-for-bitcoin-wallets/
>>>>>
>>>>>
>>>>> [3] http://wireless.subsignal.org
>>>>> [4] http://wireless.subsignal.org/index.php?title=Main_Page_en
>>>>> [5] https://dev.openwrt.org/ticket/7552
>>>>
>>>> I tried this on some of my devices (BCM4318 G-PHY and BCM4322 N-PHY)
>>>> and
>>>> it is easily reproducible on all tested devices when restricting the
>>>> rates to 11 and 12 MBit/s.
>>>>
>>>> I have the Broadcom device working as an Access point (on a MIPS SoC)
>>>> and a Laptop with an Intel Wifi device is connected to it. I generated
>>>> the traffic with iperf. If the Access Points sends the traffic the
>>>> problem occurs, if it is just receiving there is not problem.
>>>>
>>>> After the problem occurred b43_generate_txhdr is called rarely ( every
>>>> ~10 seconds) and I am not able to stay connected or connect to the
>>>> network any more. I am not familiar with the internal flow in b43 or
>>>> mac80211 could someone give me a hint where to look.
>>>>
>>>> I can not see any special changes between CCK and OFDM rates before it
>>>> goes down there are many changes without a problem before it goes down.
>>>>
>>>> Currently I do not have a Broadcom wifi card running in a x86 device
>>>> just mips devices could someone try to reproduce the problem on a x86
>>>> device.
>>>>
>>>> I added the b43 mailing list and Rafa?.
>>>
>>> Hauke or Bastian,
>>>
>>> Do you have any info whether the failure occurs with the change from
>>> OFDM to CCK, or vice versa? I am wondering if the radio needs a dummy
>>> transmission when the switch happens. I will try to put together a patch
>>> to test that hypothesis.
>>>
>>> Larry
>>
>> It is strange. The stop does not occur directly after changing from OFDM
>> to CCK or vice versa. TX seams to still work, but the device does not
>> receive anything any more.
>>
>> Here are some logs from my device:
>> http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.txt
>> Patch used:
>> http://hauke-m.de/files/b43/wifi-stop/2012-08-22/b43-ap-block.patch
>>
>> "iw dev wlan0 set bitrates legacy-2.4 11 12" was issued at ~120.000000.
>>
>> How do I monitor this particular channel with an other wifi card to get
>> most of the packages, with aircrack I am unable to set the channel?
> 
> Thanks for the log and the patch you used.
> 
> You should be able to use Kismet and set the channel; however, I usually
> let it capture everything, and then use wireshark to analyze the pcap
> file. That way, it is fairly easy to set filters to exclude the unwanted
> traffic from other AP and STA sources.
> 
> I don't use wireshark to capture the data because the box I use does not
> have a GUI desktop, and the command-line kismet is perfect for that setup.
> 
> Larry

Hi Larry,

I did some further debugging and saw that the driver gets an interrupt
indicating some new received frames, but b43_dma_rx does not fetch any
new frames.

Here are some logs from my device:
http://hauke-m.de/files/b43/wifi-stop/2012-08-25/b43-ap-block-2.log
Patch used:
http://hauke-m.de/files/b43/wifi-stop/2012-08-25/b43-ap-block-2.patch

Sometime after 210 my wifi client disconnects from the network.

With PIO the AP goes down when trying to connect to it with a wifi client.

Hauke

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Bastian Bittorf]

> How do I monitor this particular channel with an other wifi card to
> get
> most of the packages, with aircrack I am unable to set the
> channel?

the simple approach is installing horst on another router
or your pc. ofcourse you get a full dump with wireshark
sniffing on your monitor-interface.

bye, bastian

WRT54g / b43 / mac802.11 BREAKTHROUGH

[Bastian Bittorf]

> Do you have any info whether the failure occurs with the change
> from OFDM to 
> CCK, or vice versa? I am wondering if the radio needs a dummy

i cannot answer this question - interesting idea.
i like to test your patch, simply do a dummy tx in both cases.

bye, bastian