linux-kernel - Re: [patch] x86, bts: improve help text for BTS config

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Date:	Mon, 20 Oct 2008 15:26:44 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Markus Metzger <markus.t.metzger@...el.com>
Cc:	hpa@...or.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	markus.t.metzger@...il.com, akpm@...ux-foundation.org,
	Roland Dreier <rdreier@...co.com>
Subject: Re: [patch] x86, bts: improve help text for BTS config


* Markus Metzger <markus.t.metzger@...el.com> wrote:

> Improve the help text of the X86_PTRACE_BTS config.
> Make X86_DS invisible and depend on X86_PTRACE_BTS.
> 
> Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>

applied the patch below to tip/x86/urgent, thanks Markus! (only a small 
change, added the Reported-by: Roland Dreier line)

	Ingo

-------------->
>From e4254fd175d2ebaa7d72ce33245c41ca34370a7e Mon Sep 17 00:00:00 2001
From: Markus Metzger <markus.t.metzger@...el.com>
Date: Fri, 17 Oct 2008 09:09:27 +0200
Subject: [PATCH] x86, bts: improve help text for BTS config

Improve the help text of the X86_PTRACE_BTS config.
Make X86_DS invisible and depend on X86_PTRACE_BTS.

Reported-by: Roland Dreier <rdreier@...co.com>
Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/Kconfig.cpu |   24 ++++++++++++------------
 1 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 0b7c4a3..b815664 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -513,19 +513,19 @@ config CPU_SUP_UMC_32
 	  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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