6.1-RELEASE / 6.2 Kernel Crash...

[Jan Knepper]

Robert Watson wrote:
> On Thu, 28 Dec 2006, Jan Knepper wrote:
>
>>> Sounds like a bug in the support for your ATA hardware, or your 
>>> hardware is broken.  The very least you'll need to do is to obtain a 
>>> crashdump and debugging backtrace (see the developers handbook) and 
>>> CC it to sos@
>>>
>> This is getting funnier...
>> I added:
>> dumpdev="AUTO"
>> to: rc.conf
>> Rebooted the system and tried to get it to crash again...
>> And indeed it does in process 9: taskq
>>
>> Then it starts dumping which takes a couple of seconds as the machine 
>> has 2 GB Ram...
>>
>> Than it reboots... and the next thing you know... savecore does NOT 
>> recognize a dump on the swap file system. If does not save anything 
>> to /var/crash... <sigh> Tried this about 10 times... No luck...
>>
>> Any other idea's?
>
> Yeah, unfortunately if some combination of storage driver and hardware 
> aren't working, it's hard to get a dump...
No kidding!
> The usual fallback here is to use a serial console to capture 
> debugging information from DDB and to skip the dump side of things.  
> In fact, I prefer debugging that way most of the time.  The reason for 
> using a serial console (or firewire) is to avoid having to hand-copy 
> trap and debugging information, which gets very painful very quickly.  
> Compile DDB and KDB into your kernel, and configure a serial console, 
> and a panic should lead to the system entering the debugger.  The 
> usual first command to type is "trace" to generate a backtrace; it's 
> often useful also to do "show pcpu", "show allpcpu", "alltrace", and 
> "ps", although for the problem you're seeing the last two may be less 
> useful.
>
> The 0x50 trap address in your post suggests this is a NULL pointer 
> dereference.  What we now need to do is work out what piece of code is 
> dereferencing the pointer improperly, which is where the backtrace 
> comes in.
>
> If you could copy and paste all that DDB/KDB output into an e-mail 
> (or, perhaps more ideally, a PR), that would be great.
Thanks for the reply Robert.
Since this machine runs at my house I hope to get to this over the 
weekend. I will definitely try to get this information out as soon as I 
decently can.

Thanks!
Jan Knepper