tracing/fastboot: Document the need of initcall_debug

To use boot tracer, one should pass initcall_debug as well as
ftrace=initcall to the command line.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A48735E.9050002@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 1551f47e7669ba06f5e010410e9408cb9de07eb4..019f380fd764c80354ed277cfc72b7a2e4906b19 100644 (file)
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -226,13 +226,13 @@ config BOOT_TRACER
          the timings of the initcalls and traces key events and the identity
          of tasks that can cause boot delays, such as context-switches.
 
-         Its aim is to be parsed by the /scripts/bootgraph.pl tool to
+         Its aim is to be parsed by the scripts/bootgraph.pl tool to
          produce pretty graphics about boot inefficiencies, giving a visual
          representation of the delays during initcalls - but the raw
          /debug/tracing/trace text output is readable too.
 
-         You must pass in ftrace=initcall to the kernel command line
-         to enable this on bootup.
+         You must pass in initcall_debug and ftrace=initcall to the kernel
+         command line to enable this on bootup.
 
 config TRACE_BRANCH_PROFILING
        bool