Re: help on debugging kernel module in Xen

[Brendan Cully <brendan@cs.ubc.ca>]

On Friday, 12 January 2007 at 18:04, Lily Huang wrote:
> That's a great point. I just disabled the "Detect Soft Lockup" option in the
> "kernel hacking" group. Now the soft lockup disappeared and I can debug
> kernel now.
> 
> Next, I tried to debug kernel module in domU. New problem occurs.
> 
> After I set "br xxx(function in a loaded kernel module" and then "cont", I
> worked in the domu to activate the breakpoint.
> 
> Unfortunately, I found domU immediately print error messages:
> 
> /**********************************************************/
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: int3: 0000 [#1]
> <----------------------------------------------------- seems to be a problem
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: SMP
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: CPU:    0
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: EIP is at nfs3_proc_readdir+0xd/0x100 [nfs]
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: eax: daa0c740   ebx: 00001000   ecx: c1353aa0   edx: db25cd14
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: esi: df02ced0   edi: daa0885c   ebp: da9c7d34   esp: da9c7c4c
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: ds: 007b   es: 007b   ss: 0069
> 
> Message from syslogd@normal at Fri Jan 12 17:54:41 2007 ...
> normal kernel: Process ls (pid: 1670, threadinfo=da9c6000 task=c05d7070)
> /**********************************************************/
> 
> Looks like "int 3" triggered kernel error. Why just for kernel module
> debugging?

I'm afraid you're beyond my knowledge at this point.