Re: [Xen-devel] gdbserver-xen / gdb crashing domU

[Kip Macy <kip.macy@xxxxxxxxx>]

I vaguely recall it depending on debug as silly as that sounds. I'll have to go back and take a look - xen clearly isn't pausing the domain when an int3 is hit.

 

      -Kip

 

On 9/28/05, Jonathan M. McCune <jonmccune@xxxxxxx> wrote:

Hi Kip,

Thanks for your quick response.  Unfortunately, in the experiment I
described in my first post, I did have domu_debug=y in xen/Rules.mk.  I
rebuilt and reinstalled xen after a `make clean` in the xen subdir just
to be sure it would have picked up the change.

Any other ideas?

Thanks,
-Jon

Kip Macy wrote:

>domu_debug must be enabled in xen's Rules.mk <http://Rules.mk>, otherwise
>the int3 gets passed onto the OS which will cause it to crash as it isn't
>expecting to see a debug trap in ring 0 (unless of course you have a
>debugger compiled into the kernel itself).
>
>Just re-compile and then pass -p (pause) to xm create followed by an attach
>with gdbserver-xen.
>
>-Kip
>
>On 9/27/05, Jonathan M. McCune < jonmccune@xxxxxxx> wrote:
>
>
>>Hello,
>>
>>I'm trying to use gdb and gdbserver-xen to walk through the instructions
>>executed when starting up a domU kernel. We are using the current
>>xen-unstable (linux-2.6.12-xenU). I have followed the instructions in
>>tools/debugger/gdb/ and I am able to successfully attach to a running
>>domU kernel. I have compiled the domU kernel with debug options as
>>described in tools/debugger/gdb/README. After attaching to the running
>>domU kernel, I observe the following behavior:
>>
>>Issuing the gdb commands 'step', 'stepi', 'next', and 'nexti' when the
>>domU kernel is initially paused all crash the domU kernel silently
>>(i.e., the state of said domU goes to 'c' if you issue an `xm list` in
>>dom0). 'continue' causes the domU kernel to boot up correctly.
>>
>>All the breakpoints I've tried setting so far (setting the breakpoints
>>before issuing the 'continue' in gdb) cause the domU kernel to panic
>>when the function at which the breakpoint is set gets run. Functions
>>I've tried setting breakpoints for include dup_task_struct, queue_work,
>>scheduler_tick, and activate_task.
>>
>>Is it possible to step through the domU kernel code as it is booted in
>>Xen?
>>
>>Thanks,
>>-Jon
>>
>>
>>
>>_______________________________________________
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>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>http://lists.xensource.com/xen-devel
>>
>>
>>
>>
>>
>>
>
>
>

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