Re: [Qemu-devel] qemu-2.2 using trace event

[Stefan Hajnoczi]

On Tue, Nov 3, 2015 at 9:13 AM, 浩樊啊 <address@hidden> wrote:

Please keep address@hidden on CC so the discussion stays on the
mailing list where others can participate.

> you mean that qemu-system-x86_64 .....   is a command to start a vm?
> can I just start a vm by a xml file and then use qemu-system_x86_64 -trace
> events=/tmp/events trace the vm?

No, each QEMU process is a separate VM.  Launching a new QEMU does not
attach to an existing QEMU process.

If you want to "attach" to a running QEMU process, you can use the
SystemTap tracing backend.  Make sure that your QEMU binary was built
with ./configure --enable-trace-backend=dtrace (that is the case in
Fedora and Red Hat-based distributions).  Take a look at the
/usr/share/systemtap/tapset/qemu-system-x86_64.stp tapset and
SystemTap documentation here:
https://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps
https://sourceware.org/systemtap/SystemTap_Beginners_Guide/

Stefan