Re: [Xen-devel] help on debugging kernel module in Xen

["Lily Huang" <ushuanglily@xxxxxxxxx>]

Oh. I found that gdbserver printed out some error messages:

unsupported xc_ptrace request PTRACE_SETFPXREGS
unsupported xc_ptrace request PTRACE_SETFPREGS

Are they the reason why the breakpoint does not work?

lily

On 1/12/07, Lily Huang <ushuanglily@xxxxxxxxx> wrote:

Many thanks for your help!

I tried the command "target remote 127.0.0.1:9999", and got the response:

/******************************************************************************/
Remote debugging using 127.0.0.1:9999
[New Thread 0]
[Switching to Thread 0]
0xc01013a7 in hypercall_page ()
warning: shared library handler failed to enable breakpoint  <------------------ this could be a problem
/******************************************************************************/

then, I did "br filp_open", and then "cont".

But no matter what file I opened in domU, the breakpoint is never encountered. It appears that the breakpoint is not activate.

I googled but cannot find answer so far.

Did you run into similar problems?

Thanks,
lily

On 1/12/07, Brendan Cully < brendan@xxxxxxxxx > wrote:

On Friday, 12 January 2007 at 15:25, Lily Huang wrote:
> Thanks, Brendan.
>
> I followed the README instruction and did follows:
>
> 1. start a domU
> 2. in Dom0, run "gdbserver-xen 127.0.0.1:9999 --attach 5", where 5 is the
> domain id of the domU
> 3. I got the response:
> /*******************************/
> Attached; pid = 5
> Listening on port 9999
> /*******************************/
> And then, I lost connection with the domU, I tried both network and console,
> neither works for me.

when the debugger attaches, it pauses the guest.

> 4. I run "gdb /boot/vmlinux-syms-2.6.16.33-xenU" in dom0, hoping to
> reactivate domU with debug command.
>
> the response is as follows:
>
> /*******************************/
> GNU gdb Red Hat Linux (6.3.0.0-1.84rh)
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for details.
> This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db
> library "/lib/libthread_db.so.1".
> /*******************************/
>
> when I typed "cont" command in the gdb, I got "The program is not being
> run."
>
> Am I doing something wrong? Any further help will be highly appreciated.

you need to attach to the domain from within gdb:

target remote localhost:9999

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