From 1221e50b4aa60b98aade37eb4e536d4a2cb93e75 Mon Sep 17 00:00:00 2001
From: Thomas Falcon <thomas.falcon@intel.com>
Date: Fri, 12 Jun 2026 14:28:47 -0500
Subject: [PATCH] perf tools: Document recent additions to the perf.data file
 header

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.

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 0e4d0ecc9e125..b90cba9168f84 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
-- 
2.47.3