On Sun, Jun 22, 2014 at 02:43:03AM +0800, Yang Zhiyong wrote:
> We have the experience that the guest doesn't stop successfully 
> though it was instructed to shut down.
> 
> The root cause may be not in QEMU mostly.  However, QEMU is often
> suspected at the beginning just because the issue occurred in
> virtualization environment.
> 
> Therefore, we need to affirm that QEMU received the shutdown  
> request and raised ACPI irq from "virsh shutdown" command, 
> virt-manger or stopping QEMU process to the VM .
> So that we can affirm the problems was belonged to the Guset OS 
> rather than the QEMU itself.
> 
> When we stop guests by "virsh shutdown" command or virt-manger, 
> or stopping QEMU process, qemu_system_powerdown_request() or
> qemu_system_shutdown_request() is called. Then the below functions 
> in main_loop_should_exit() of Vl.c are called roughly in the 
> following order.
> 	
> 	if (qemu_powerdown_requested()) 
> 		qemu_system_powerdown()
> 			monitor_protocol_event(QEVENT_POWERDOWN, NULL)
> 		
> 	OR
> 	
> 	if(qemu_shutdown_requested()} 
> 		monitor_protocol_event(QEVENT_SHUTDOWN, NULL);
> 
> The tracepoint of monitor_protocol_event() already exists, but no
> tracepoints are defined for qemu_system_powerdown_request() and 
> qemu_system_shutdown_request(). So this patch adds two tracepoints for 
> the two functions. We believe that it will become much easier to 
> isolate the problem mentioned above by these tracepoints.
> 
> 
> Signed-off-by: Yang Zhiyong <yangzy.fnst@cn.fujitsu.com>
> 
> ---
>  trace-events |    2 ++
>  vl.c         |    2 ++
>  2 files changed, 4 insertions(+), 0 deletions(-)

Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing

Stefan