[Qemu-devel] Accessing a linux guest's data structures

[Qemu-devel] Accessing a linux guest's data structures

[Ankur Dahiya]

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Hi
I am a beginner qemu developer.
I am running a linux guest inside qemu and I need to determine what
process, thread is currently running in the guest.
How should I do this? Any suggestions? Or can anyone point me to the
relevant areas in qemu's source.

Thanks.
Ankur Dahiya

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Re: [Qemu-devel] Accessing a linux guest's data structures

[Mulyadi Santosa]

On Sun, Nov 6, 2011 at 23:01, Ankur Dahiya <legalos.lotr@gmail.com> wrote:
> Hi
> I am a beginner qemu developer.
> I am running a linux guest inside qemu and I need to determine what process,
> thread is currently running in the guest.
> How should I do this? Any suggestions? Or can anyone point me to the
> relevant areas in qemu's source.

Do you want to do that in kernel perspective or user mode perspective?

How about simply ssh-ing into the guest and run "ps"?



-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

Re: [Qemu-devel] Accessing a linux guest's data structures

[Mulyadi Santosa]

Hi :)

On Mon, Nov 7, 2011 at 00:46, Ankur Dahiya <legalos.lotr@gmail.com> wrote:
> Hey, thanks for the reply.
> I dont want to ssh to the guest!
> What I basically want to do is monitor the guest state. Like I want to track
> what system calls are being called,
> what process and thread are currently running...Things that an
> instrumentation framework like valgrind does...
> But i want to do it without disturbing the guest (transparent to the guest).
> Is this too difficult? Any suggestions?

Alright, I got better understanding upon your need.

OK, I suggest to explore kdb/kgdb and hook gdb from host into it via
the qemu's gdb stub. I think that should do it.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

Re: [Qemu-devel] Accessing a linux guest's data structures

[陳韋任]

> > Hi
> > I am a beginner qemu developer.
> > I am running a linux guest inside qemu and I need to determine what process,
> > thread is currently running in the guest.
> > How should I do this? Any suggestions? Or can anyone point me to the
> > relevant areas in qemu's source.
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  I guess he want to know how to know which process is running in the
guest OS from QEMU's perspective.

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667

Re: [Qemu-devel] Accessing a linux guest's data structures

[Andreas Färber]

Am 08.11.2011 06:27, schrieb 陳韋任:
>>> I am running a linux guest inside qemu and I need to determine what process,
>>> thread is currently running in the guest.
>>> How should I do this? Any suggestions? Or can anyone point me to the
>>> relevant areas in qemu's source.
>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   I guess he want to know how to know which process is running in the
> guest OS from QEMU's perspective.

And QEMU doesn't know or care, as a processor emulator.
Therefore in some way the guest's cooperation is needed.

HTE,
Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] Accessing a linux guest's data structures

[Vasiliy Tolstov]

2011/11/8 Andreas Färber <afaerber@suse.de>:
> Am 08.11.2011 06:27, schrieb 陳韋任:
>>>> I am running a linux guest inside qemu and I need to determine what process,
>>>> thread is currently running in the guest.
>>>> How should I do this? Any suggestions? Or can anyone point me to the
>>>> relevant areas in qemu's source.
>>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>   I guess he want to know how to know which process is running in the
>> guest OS from QEMU's perspective.
>
> And QEMU doesn't know or care, as a processor emulator.
> Therefore in some way the guest's cooperation is needed.
>

Try to see on libvmi (successor of xenaccess). Tou need vm
introspection that can be possible via libvmi.


-- 
Vasiliy Tolstov,
Clodo.ru
e-mail: v.tolstov@selfip.ru
jabber: vase@selfip.ru

Re: [Qemu-devel] Accessing a linux guest's data structures

[Ankur Dahiya]

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Thanks for the suggestions, guys! I will take a look at libvmi.
As an aside, can someone tell me where in the qemu source can I inspect
each guest instruction?
I want all guest instructions to first go through my code.

Ankur Dahiya


On Tue, Nov 8, 2011 at 3:18 PM, Vasiliy Tolstov <v.tolstov@selfip.ru> wrote:

> 2011/11/8 Andreas Färber <afaerber@suse.de>:
> > Am 08.11.2011 06:27, schrieb 陳韋任:
> >>>> I am running a linux guest inside qemu and I need to determine what
> process,
> >>>> thread is currently running in the guest.
> >>>> How should I do this? Any suggestions? Or can anyone point me to the
> >>>> relevant areas in qemu's source.
> >>     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >>   I guess he want to know how to know which process is running in the
> >> guest OS from QEMU's perspective.
> >
> > And QEMU doesn't know or care, as a processor emulator.
> > Therefore in some way the guest's cooperation is needed.
> >
>
> Try to see on libvmi (successor of xenaccess). Tou need vm
> introspection that can be possible via libvmi.
>
>
> --
> Vasiliy Tolstov,
> Clodo.ru
> e-mail: v.tolstov@selfip.ru
> jabber: vase@selfip.ru
>

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Re: [Qemu-devel] Accessing a linux guest's data structures

[陳韋任]

> Thanks for the suggestions, guys! I will take a look at libvmi.
> As an aside, can someone tell me where in the qemu source can I inspect
> each guest instruction?
> I want all guest instructions to first go through my code.

  For i386 guest, see disas_insn (target-i386/translate.c). It
disassembles i386 guest binary. QEMU provides "-d in_asm" option
to log every guest instruction it translates. You might want to
take a look on qemu_log.

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667