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

[Paul Brook]

>   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.

Paul