[Qemu-devel] QEMU simpletrace.py

[Qemu-devel] QEMU simpletrace.py

[Derrick McKee]

Hi,

I am having trouble using the simpleparser.py script in QEMU.  Hopefully, I
am doing something incorrect and you can quickly set me back on course.

I have generated a trace file as per the instructions in
docs/devel/tracing.txt.  However, whenever I try to run the simpleparser.py
script I get a file not found error:

<QEMU source>/build/scripts/simpletrace.py trace-events-all trace-30218
Traceback (most recent call last):
  File "/home/derrick/code/qemu/build/scripts/simpletrace.py", line 262, in
<module>
    run(Formatter())
  File "/home/derrick/code/qemu/build/scripts/simpletrace.py", line 236, in
run
    events = read_events(open(sys.argv[1], 'r'))
IOError: [Errno 2] No such file or directory: 'trace-events-all'

It seems like the python script is considering 'trace-events-all' as a
file, but the directions don't make it seem like it should be a file.
Thoughts?  Thanks
-- 
Derrick McKee
Ph.D. Student at Purdue University

Re: [Qemu-devel] QEMU simpletrace.py

[Stefan Hajnoczi]

On Fri, Sep 01, 2017 at 03:52:03PM +0000, Derrick McKee wrote:
> I am having trouble using the simpleparser.py script in QEMU.  Hopefully, I
> am doing something incorrect and you can quickly set me back on course.
> 
> I have generated a trace file as per the instructions in
> docs/devel/tracing.txt.  However, whenever I try to run the simpleparser.py
> script I get a file not found error:
> 
> <QEMU source>/build/scripts/simpletrace.py trace-events-all trace-30218
> Traceback (most recent call last):
>   File "/home/derrick/code/qemu/build/scripts/simpletrace.py", line 262, in
> <module>
>     run(Formatter())
>   File "/home/derrick/code/qemu/build/scripts/simpletrace.py", line 236, in
> run
>     events = read_events(open(sys.argv[1], 'r'))
> IOError: [Errno 2] No such file or directory: 'trace-events-all'
> 
> It seems like the python script is considering 'trace-events-all' as a
> file, but the directions don't make it seem like it should be a file.

trace-events-all is a file that is generated at build time.  It is
needed by simpletrace.py.

You can find the trace-events-all file in the root directory of your
QEMU build tree.

The documentation says:

  The individual "trace-events" files are merged into a "trace-events-all" file,
  which is also installed into "/usr/share/qemu" with the name "trace-events".

If you can think of a way to make the documentation clearer, please feel
free to send a patch.  Guidelines on submitting patches are here:
https://wiki.qemu.org/index.php/Contribute/SubmitAPatch

Stefan