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@cisco.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 0b7c4a3f0651e8e03e7f0c8ea3083bab77775812..b815664fe3700b77aa031fab7711be4128c858d1 100644 (file)
--- 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.