Re: [Xenomai-help] CAN errors and real-time behaviour (IRQ raise forever and may lock system)

["Stéphane ANCELOT" <sancelot@domain.hid>]

Sebastian Smolorz wrote:
> Stéphane ANCELOT wrote:
>> I have checked what has happened when nothing plugged on canbus:
>>
>> a bus error occured .
>> when bus error occurs the ecc register contains possible error information.
>> once we read the ecc register (in isr routine) the error code register
>> mechanism is enabled again . Thus another bus error interrupt appears
>> again and a new BEI ocurs
>>
>> In this case, the system spend time in the ISR routine of the CAN
>> driver.It gives you enough time to run a linux console , but not to
>> launch other tasks like X...
>>
>> It would be necessary to find a way to manage this kind of problem and
>> avoiding enabling forever Bus Error Interrupt.
> 
> Note that the current implementation of RT-Socket-CAN shows this behaviour on 
> purpose. See also [1] ("may flood!"). Whether this is the right handling or 
> not may be discussed here. I admit that the current implementation forces an 
> application developer to take more responsibility but that is not a bug of 
> the underlying driver/stack per se. Look, you don't connect anything to the 
> CAN bus, start a *real-time* application which sends a message to a 
> non-existent CAN node. This is an error situation an it is more than ever for 
> a real-time task. So the proper reaction for a RT-application would be to 
> handle those errors and e.g. shut down the CAN interface which in this case 
> will force the CAN hardware to stop its endless attempts to send the message.

I agree and this is what I was doing , however this does not seem to 
work as expected in the driver.



> [1]http://www.xenomai.org/documentation/trunk/html/api/group__rtcan.html#g0b068b1221129441b89967ee2ddb9f44
> 
> --
> Sebastian
> 
>