From: Vince Weaver <vincent.weaver@maine.edu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org,
Josh Poimboeuf <jpoimboe@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Stephane Eranian <eranian@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [perf] perf_event.h ABI visibility question
Date: Fri, 24 Aug 2018 17:09:27 -0400 (EDT) [thread overview]
Message-ID: <alpine.DEB.2.21.1808241706120.12717@macbook-air> (raw)
In-Reply-To: <20180824085042.GL24124@hirez.programming.kicks-ass.net>
On Fri, 24 Aug 2018, Peter Zijlstra wrote:
> > +++ b/include/uapi/linux/perf_event.h
> > @@ -143,6 +143,8 @@ enum perf_event_sample_format {
> > PERF_SAMPLE_PHYS_ADDR = 1U << 19,
> >
> > PERF_SAMPLE_MAX = 1U << 20, /* non-ABI */
> > +
> > + __PERF_SAMPLE_CALLCHAIN_EARLY = 1ULL << 63,
> > };
> >
>
> Hurphm.. visible yes, but as you say, also quite useless. Does it really
> make sense to document that?
Well, it should probably be documented either in the manpage or else in
perf_event.h (even if it's just "internal use, don't use") as we can't
really expect people to download a git tree and do a git-blame to try to
figure out what this mysterious field is all about.
Also, this change increased the size of the enum from 32 to 64 bits on
32-bit machines, though that only really matters if the user is doing
something really weird with enum variables.
Vince
next prev parent reply other threads:[~2018-08-24 21:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-23 18:25 [perf] perf_event.h ABI visibility question Vince Weaver
2018-08-24 8:50 ` Peter Zijlstra
2018-08-24 21:09 ` Vince Weaver [this message]
2018-08-27 7:52 ` Peter Zijlstra
2018-08-28 17:51 ` Vince Weaver
2018-08-29 12:13 ` Peter Zijlstra
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