From 459c6d15a0c52bae43842ff2cd0dd41aa7de9b7f Mon Sep 17 00:00:00 2001
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Sat, 19 Sep 2009 07:14:15 +0200
Subject: [PATCH] tracing: Document HAVE_SYSCALL_TRACEPOINTS needs

Document the arch needed requirements to get the support for syscalls
tracing.

v2: HAVE_FTRACE_SYSCALLS have been changed to HAVE_SYSCALL_TRACEPOINTS
    recently. Update this config name in the documentation then.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
---
 Documentation/trace/ftrace-design.txt | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 7003e10f10f..641a1ef2a7f 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -213,10 +213,19 @@ If you can't trace NMI functions, then skip this option.
 <details to be filled>
 
 
-HAVE_FTRACE_SYSCALLS
+HAVE_SYSCALL_TRACEPOINTS
 ---------------------
 
-<details to be filled>
+You need very few things to get the syscalls tracing in an arch.
+
+- Have a NR_syscalls variable in <asm/unistd.h> that provides the number
+  of syscalls supported by the arch.
+- Implement arch_syscall_addr() that resolves a syscall address from a
+  syscall number.
+- Support the TIF_SYSCALL_TRACEPOINT thread flags
+- Put the trace_sys_enter() and trace_sys_exit() tracepoints calls from ptrace
+  in the ptrace syscalls tracing path.
+- Tag this arch as HAVE_SYSCALL_TRACEPOINTS.
 
 
 HAVE_FTRACE_MCOUNT_RECORD