Re: [Qemu-devel] Query regarding IO paths in QEMU

[Stefan Hajnoczi]

On Mon, May 06, 2013 at 02:36:46PM -0700, aayush gupta wrote:
> Thanks for the reply. I am trying to use the tracing with qemu-io as
> suggested in docs/tracing.txt. I did the following steps:
> 
> 1. Configure and make with simple backend
> 2. Create a set of events I am interested in (/tmp/events)
> 3. Now I am running the qemu-iotests by adding T= /tmp/events to  test 001
> testcase (file read path only).
> It runs and generates a trace-xxxxx file. However, the file just has a
> couple of lines in it in binary.
> 4. When I pass it through simpletrace.py nothing happens.
> 
> Can you tell me if I missed some step or something else needs to be done.

Invoke simpletrace.py like this:

  $ scripts/simpletrace.py trace-events <trace-file>

If tracing doesn't work with qemu-iotests, try it manually first:

  $ qemu-io -T /tmp/events -c 'read 0 512' test.img

Stefan