Re: [Qemu-devel] How to follow a child process created in the guest OS?

[陳韋任]

On Fri, Feb 10, 2012 at 11:48:05PM +0000, Paul Brook wrote:
> >   I am running this tiny OS on QEMU then using GDB to connect it.
> > 
> > I want to follow task 1 after the forking, but it seems that GDB
> > stick with task 0 and cannot follow task 1 even I do `set follow-fork-mode
> > child`.
> 
> You have exactly one CPU. That's what the qemu GDB stub exposes.  Multiple 
> processes are an illusion created by your operating system.  It is not 
> something qemu knows or cares about.
> 
> In most cases if you want to do debugging within that OS created illusion 
> (aka 
> a userspace process) then you probably don't want to be using a hardware 
> debug 
> probe (i.e. the qemu gdb stub) at all. Instead you want to be using the debug 
> facilities provided by your operating system.  On linux this would be ptrace, 
> probably via gdbserver.

  I see. Thanks.

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
Homepage: http://people.cs.nctu.edu.tw/~chenwj