anyone seen this problem..

[Julian Elischer]

Adam Kropelin wrote:

> Julian Elischer wrote:
>
>> Julian Elischer wrote:
>>
>>>
>>> I'm working in 4.10++  plus a few MFC patches..
>>>
>>> One of our applications regularly crashes when using a uhid device.
>>
>>
>>
>> ^^^^^ ugen
>
>
> I've been able to panic the kernel fairly easily using ugen (this is 
> on 5.2.1 and 5.3). The trigger seems to be a length mismatch where the 
> device returns a different amount of data than was expected for a 
> particular transfer. I'm suspecting memory corruption since it will 
> often fail the ioctl a few times before actually panicing.
>
> I am not sufficiently clued to obtain a kernel backtrace like you did. 
> I presume I need to configure something to dump me into a kernel 
> debugger upon panic instead of the automatic reboot I'm currently 
> getting. I'll read up on such things and see if I can determine how 
> closely my situation matches yours. 


you need to set
dumpdev="/dev/ad0s1b"
in /etc/rc.conf

and after the next boot.
cd /(kernelcompile directory)
kgdb kernel.debug /var/crash/vmcore.0

(probably best to make /var/crash a symlink somewhere with more space)

'bt' to get a stacktrace.

>
>
> --Adam