Re: [Qemu-devel] About the trace framework

[Xie Changlong]

在 7/11/2017 9:33 AM, Wang Dong 写道:
> On 07/10/2017 01:24 PM, Xie Changlong wrote:
> > 在 7/9/2017 5:57 PM, Wang Dong 写道:
> > > Hi,
> > >
> > > I am new to QEMU. But I got some problem so that  I want to figure it 
> > > out.
> > >
> > > So I try to debug qemu to see what happened.
> > >
> > > And I found trace framework. I think this will help me understand the 
> > > point.
> > >
> > > So I compiled qemu with option:
> > >
> > > ## *--enable-trace-backends=simple*
> > >
> > > And did as the docs/tracing.txt tell. But when I execute the example 
> > > command in it, nothing just happens.
> > >
> > > *./scripts/simpletrace.py trace-events-all trace-xxxxxx(my trace file 
> > > produced by qemu)
> > > I am not sure what happened. Just ask this.
> > > Any clue will be appreciated. Thanks in advance.
> > > *
> >
> > Did you set *trace-event*? I've encountered this issue in the past :)
> > (qemu) help trace-event
> > trace-event name on|off -- changes status of a specific trace event
> > (qemu) info trace-events
> yes, I set it. I just did as the docs told. If this does not work or 
> misses something, it should be corrected I think.
>
> Have you also tried out the examples in docs? how did you do that? I 

Yes, just follow the docs. No something special.

> think I misses some. Could you tell more about
> it? Thanks.

You should confirm the *trace-event*s you set are really triggered by 
qemu. Use gdb breakpoint to verify it is a good choice.

>

--
Thanks
    -Xie