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Subject: Re: [Qemu-devel] How to follow a child process created in the guest
 OS?
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To: =?UTF-8?B?6Zmz6Z+L5Lu7?= <chenwj@iis.sinica.edu.tw>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org

Am 10.02.2012 11:26, schrieb =E9=99=B3=E9=9F=8B=E4=BB=BB:
> On Fri, Feb 10, 2012 at 08:14:41AM +0000, Stefan Hajnoczi wrote:
>> On Thu, Feb 09, 2012 at 06:33:16PM +0800, =E9=99=B3=E9=9F=8B=E4=BB=BB =
wrote:
>>> I am running a tiny OS on QEMU and debugging it with gdbstub. The tin=
y OS will
>>> fork process 1, 2, ... and so on. I want to follow the child process,=
 [...]
>>>
>>>   Is there a way to do what I'm trying to do? Thanks!

> ----------------- Tiny OS code -----------------------------
> void main(void)   /* This really IS void, no error here. */
> {
>   /* initialize enviroment */
>=20
>   sti();
>   move_to_user_mode();
>   if (!fork()) {    /* we count on this going ok */
>     init();         // task 1
>   }
>=20
>   for(;;) pause();  // task 0
> }=20
> ------------------------------------------------------------
>=20
>   I am running this tiny OS on QEMU then using GDB to connect it.
> I want to follow task 1 after the forking, [...]

Since this seems to be your code, if this were PowerPC I'd simply try to
place via inline assembler a trap instruction first thing inside the
init() function. That can easily be caught in gdbstub.

Depending on what you really want to do, you could always try some
printf-style output to serial. ;)

Andreas

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