linux-kernel - [rfc] x86, bts: improve X86_PTRACE

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Message-ID: <20081015182902.A30726@sedona.ch.intel.com>
Date:	Wed, 15 Oct 2008 18:29:02 +0200
From:	Markus Metzger <markus.t.metzger@...el.com>
To:	linux-kernel@...r.kernel.org, mingo@...e.hu, tglx@...utronix.de,
	rdreier@...co.com
Cc:	markus.t.metzger@...el.com, markus.t.metzger@...il.com
Subject: [rfc] x86, bts: improve X86_PTRACE_BTS help text

Improve the help text on the BTS config option.
Remove the DS config option - set it implicitly, when BTS is selected.

Signed-off-by: markus.t.metzger@...el.com

----
Index: gits/arch/x86/Kconfig.cpu
===================================================================
--- gits.orig/arch/x86/Kconfig.cpu	2008-10-15 09:02:47.000000000 +0200
+++ gits/arch/x86/Kconfig.cpu	2008-10-15 12:59:21.000000000 +0200
@@ -513,19 +513,19 @@
 	  If unsure, say N.
 
 config X86_DS
-	bool "Debug Store support"
-	default y
-	help
-	  Add support for Debug Store.
-	  This allows the kernel to provide a memory buffer to the hardware
-	  to store various profiling and tracing events.
+	def_bool X86_PTRACE_BTS
+	depends on X86_DEBUGCTLMSR
 
 config X86_PTRACE_BTS
-	bool "ptrace interface to Branch Trace Store"
+	bool "Branch Trace Store"
 	default y
-	depends on (X86_DS && X86_DEBUGCTLMSR)
+	depends on X86_DEBUGCTLMSR
 	help
-	  Add a ptrace interface to allow collecting an execution trace
-	  of the traced task.
-	  This collects control flow changes in a (cyclic) buffer and allows
-	  debuggers to fill in the gaps and show an execution trace of the debuggee.
+	  This adds a ptrace interface to the hardware's branch trace store.
+
+	  Debuggers may use it to collect an execution trace of the debugged
+	  application in order to answer the question 'how did I get here?'.
+	  Debuggers may trace user mode as well as kernel mode.
+
+	  Say Y unless there is no application development on this machine
+	  and you want to save a small amount of code size.
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