2010/11/4 Felix Fietkau <[email protected]>:
> On 2010-11-04 9:59 PM, Björn Smedman wrote:
>> Hi all,
>>
>> I'm trying to stabilize ath9k on an Atheros AR913x based platform.
>>
>> One type of problem is that sometimes, under high ath9k tx/rx load,
>> the system locks up with lots of partial oopses like below spewing out
>> on the serial. I'm not really qualified to read these but ath9k has a
>> history of memory corruption and DMA problems. That in combination
>> with the rater weird message, that __bzero and print_modules contain
>> reserved instructions, makes me think that the problem may be that
>> pages containing executable kernel code are accidentally DMA:ed over.
>> :P Is that even possible? If so, can it be made impossible? :)
>>
>> Other than that, what could it be?
>>
>> Reserved instruction in kernel code[#1]:
>> Cpu 0 [...]
>>
>> And so on until serial breaks down... Then all leds except two come on
>> and it freezes in that position. Not even the hardware watchdog can
>> get to it it seems. :(
> If not even the watchdog can recover it, then it doesn't really sound
> like a DMA issue. Last time I saw something like that on one of my
> devices, the power supply was too weak. Are you sure that it's not
> caused by a power or heat issue - or some other kind of hardware problem?

Could be heat I guess... But I've taken the cover off and I'm in
Sweden, so doesn't feel very likely. :P

It doesn't happen very often (maybe every week or so in normal
operation as a home ap) but it happens right away in some ath9k
related situations, e.g. if ath_alloc_rx_buf() fails in the RX DMA
logic. That's under the assumption that "all leds except two come on
and hardware watchdog is a kitten" is always this same problem though,
which I guess it doesn't necessarily have to be.

Just out of curiosity, is it possible to DMA over executable code?

/Björn
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