Re: [PULL 10/11] trace: document how to specify multiple --trace patterns

[BALATON Zoltan]

On Mon, 1 Feb 2021, Stefan Hajnoczi wrote:
> It is possible to repeat the --trace option to specify multiple
> patterns. This may be preferrable to users who do not want to create a
> file with a list of patterns.
>
> Suggested-by: BALATON Zoltan <balaton@eik.bme.hu>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Message-id: 20210112165859.225534-2-stefanha@redhat.com
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> docs/devel/tracing.rst | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/docs/devel/tracing.rst b/docs/devel/tracing.rst
> index af395e957d..e8f9b82c5e 100644
> --- a/docs/devel/tracing.rst
> +++ b/docs/devel/tracing.rst
> @@ -22,10 +22,15 @@ events::
> This output comes from the "log" trace backend that is enabled by default when
> ``./configure --enable-trace-backends=BACKENDS`` was not explicitly specified.
>
> -More than one trace event pattern can be specified by providing a file
> -instead::
> +Multiple patterns can be specified by repeating the ``--trace`` option::
> +
> +    $ qemu --trace "kvm_*" --trace "virtio_*" ...

Does that actually work? I've always used -trace enable="pattern1" -trace 
enable="pattern2" Not sure if omitting enable= is the same.

Regards,
BALATON Zoltan

> +
> +When patterns are used frequently it is more convenient to store them in a
> +file to avoid long command-line options::
>
>     $ echo "memory_region_ops_*" >/tmp/events
> +    $ echo "kvm_*" >>/tmp/events
>     $ qemu --trace events=/tmp/events ...
>
> Trace events
> --
> 2.29.2