x86 mmiotrace: comment about user space ABI
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/mmiotrace.h b/include/linux/mmiotrace.h
index cb24782..6ec288f 100644
--- a/include/linux/mmiotrace.h
+++ b/include/linux/mmiotrace.h
@@ -3,6 +3,10 @@
#include <asm/types.h>
+/*
+ * If you change anything here, you must bump MMIO_VERSION.
+ * This is the relay data format for user space.
+ */
#define MMIO_VERSION 0x04
/* mm_io_header.type */
@@ -23,7 +27,7 @@
};
struct mm_io_header {
- __u32 type;
+ __u32 type; /* see MMIO_* macros above */
__u32 sec; /* timestamp */
__u32 nsec;
__u32 pid; /* PID of the process, or 0 for kernel core */