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

From: Arend van Spriel
Date: Thu Jun 20 2013 - 14:28:28 EST

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


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.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at