Re: [for-next][PATCH 08/12] tracing: Add binary & filter forevents

[Arend van Spriel]

On 06/20/13 14:14, Steven Rostedt wrote:
> On Thu, 2013-06-20 at 10:09 +0200, Arend van Spriel wrote:
> > On 06/20/2013 05:35 AM, Steven Rostedt wrote:
> > > By allowing a binary '&' operation, this gives the user the ability to
> > > test a bit.
> > >
> > > Note, a binary '|' is not added, as it doesn't make sense as fields must
> > > be compared to constants (for now), and ORing a constant will always return
> > > true.
> > >
> > > Link:http://lkml.kernel.org/r/1371057385.9844.261.camel@xxxxxxxxxxxxxxxxxx
> > >
> > > Suggested-by: Arend van Spriel<arend@xxxxxxxxxxxx>
> >
> > Actually, my attempt was triggered by the trace-cmd manual page:
> >
> > "-f filter
> > Specify a filter for the previous event. This must come after a -e. This
> > will filter what events get recorded based on the content of the event.
> > Filtering is passed to the kernel directly so what filtering is allowed
> > may depend on what version of the kernel you have. Basically, it will
> > let you use C notation to check if an event should be processed or not.
> >
> > ==,>=,<=,>,<,&, |,&&  and ||
> >
> > The above are usually safe to use to compare fields."
>
> Ah thanks. That needs to be updated. Not sure why I wrote all of them.
> Perhaps because the report side handles them and I just assumed the
> kernel did too.

Reading the whole text with your remark in mind, I guess it does 
indicate there are no guarantees depending on the kernel and the list of 
operators are what trace-cmd supports. I overlooked/ignored the text 
seeing the operators.

Regards,
Arend

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/