* [PATCH] perf: Document recent additions to the perf.data file header
@ 2026-06-12 19:28 Thomas Falcon
2026-06-15 19:21 ` Ian Rogers
0 siblings, 1 reply; 3+ messages in thread
From: Thomas Falcon @ 2026-06-12 19:28 UTC (permalink / raw)
To: linux-perf-users
Cc: linux-kernel, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Namhyung Kim, Mark Rutland,
Alexander Shishkin, Jiri Olsa, Ian Rogers, Adrian Hunter,
James Clark, Dapeng Mi
Add documentation for recently added HEADER_E_MACHINE and
HEADER_CLN_SIZE data to the perf.data file. Also fix a typo
at the end of the header section.
Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
---
.../perf/Documentation/perf.data-file-format.txt | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
index 0e4d0ecc9e12..b90cba9168f8 100644
--- a/tools/perf/Documentation/perf.data-file-format.txt
+++ b/tools/perf/Documentation/perf.data-file-format.txt
@@ -464,7 +464,21 @@ struct cpu_domain_info {
struct domain_info domains[];
};
- other bits are reserved and should ignored for now
+ HEADER_E_MACHINE = 33,
+
+ELF machine and flags data. e_machine is expanded from 16 to 32 bits
+for alignment. Format:
+
+ u32 e_machine;
+ u32 e_flags;
+
+ HEADER_CLN_SIZE = 34,
+
+The size of the cacheline in bytes. Format:
+
+ unsigned int cln_size;
+
+ other bits are reserved and should be ignored for now
HEADER_FEAT_BITS = 256,
Attributes
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] perf: Document recent additions to the perf.data file header
2026-06-12 19:28 [PATCH] perf: Document recent additions to the perf.data file header Thomas Falcon
@ 2026-06-15 19:21 ` Ian Rogers
2026-06-15 19:55 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 3+ messages in thread
From: Ian Rogers @ 2026-06-15 19:21 UTC (permalink / raw)
To: Thomas Falcon
Cc: linux-perf-users, linux-kernel, Peter Zijlstra, Ingo Molnar,
Arnaldo Carvalho de Melo, Namhyung Kim, Mark Rutland,
Alexander Shishkin, Jiri Olsa, Adrian Hunter, James Clark,
Dapeng Mi
On Fri, Jun 12, 2026 at 12:28 PM Thomas Falcon <thomas.falcon@intel.com> wrote:
>
> Add documentation for recently added HEADER_E_MACHINE and
> HEADER_CLN_SIZE data to the perf.data file. Also fix a typo
> at the end of the header section.
>
> Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
> ---
> .../perf/Documentation/perf.data-file-format.txt | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
> index 0e4d0ecc9e12..b90cba9168f8 100644
> --- a/tools/perf/Documentation/perf.data-file-format.txt
> +++ b/tools/perf/Documentation/perf.data-file-format.txt
> @@ -464,7 +464,21 @@ struct cpu_domain_info {
> struct domain_info domains[];
> };
>
> - other bits are reserved and should ignored for now
> + HEADER_E_MACHINE = 33,
> +
> +ELF machine and flags data. e_machine is expanded from 16 to 32 bits
> +for alignment. Format:
> +
> + u32 e_machine;
> + u32 e_flags;
Thanks Thomas! I found that endianness was missing from the
e_machine/e_flags for capstone disassembly support. Part of me thinks
the unused 16-bits of the e_machine could carry information like this.
That said, we also have endianness information via the perf.data magic
value. Anyway:
Reviewed-by: Ian Rogers <irogers@google.com>
Ian
> +
> + HEADER_CLN_SIZE = 34,
> +
> +The size of the cacheline in bytes. Format:
> +
> + unsigned int cln_size;
> +
> + other bits are reserved and should be ignored for now
> HEADER_FEAT_BITS = 256,
>
> Attributes
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] perf: Document recent additions to the perf.data file header
2026-06-15 19:21 ` Ian Rogers
@ 2026-06-15 19:55 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2026-06-15 19:55 UTC (permalink / raw)
To: Ian Rogers
Cc: Thomas Falcon, linux-perf-users, linux-kernel, Peter Zijlstra,
Ingo Molnar, Namhyung Kim, Mark Rutland, Alexander Shishkin,
Jiri Olsa, Adrian Hunter, James Clark, Dapeng Mi
On Mon, Jun 15, 2026 at 12:21:10PM -0700, Ian Rogers wrote:
> On Fri, Jun 12, 2026 at 12:28 PM Thomas Falcon <thomas.falcon@intel.com> wrote:
> >
> > Add documentation for recently added HEADER_E_MACHINE and
> > HEADER_CLN_SIZE data to the perf.data file. Also fix a typo
> > at the end of the header section.
> >
> > Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
> > ---
> > .../perf/Documentation/perf.data-file-format.txt | 16 +++++++++++++++-
> > 1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
> > index 0e4d0ecc9e12..b90cba9168f8 100644
> > --- a/tools/perf/Documentation/perf.data-file-format.txt
> > +++ b/tools/perf/Documentation/perf.data-file-format.txt
> > @@ -464,7 +464,21 @@ struct cpu_domain_info {
> > struct domain_info domains[];
> > };
> >
> > - other bits are reserved and should ignored for now
> > + HEADER_E_MACHINE = 33,
> > +
> > +ELF machine and flags data. e_machine is expanded from 16 to 32 bits
> > +for alignment. Format:
> > +
> > + u32 e_machine;
> > + u32 e_flags;
>
> Thanks Thomas! I found that endianness was missing from the
> e_machine/e_flags for capstone disassembly support. Part of me thinks
> the unused 16-bits of the e_machine could carry information like this.
> That said, we also have endianness information via the perf.data magic
> value. Anyway:
>
> Reviewed-by: Ian Rogers <irogers@google.com>
Thanks, applied to perf-tools-next, for v7.2.
- Arnaldo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-06-12 19:28 [PATCH] perf: Document recent additions to the perf.data file header Thomas Falcon
2026-06-15 19:21 ` Ian Rogers
2026-06-15 19:55 ` Arnaldo Carvalho de Melo
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