unwind: Add Makefile and Kconfig entries for ARM stack unwinding

This patch also makes the frame pointer default to y only if
!ARM_UNWIND. LOCKDEP no longer selects FRAME_POINTER if ARM_UNWIND is
enabled.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index a7a01289a480..0a2d2be0152e 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -2,18 +2,29 @@ menu "Kernel hacking"
 
 source "lib/Kconfig.debug"
 
-# RMK wants arm kernels compiled with frame pointers so hardwire this to y.
+# RMK wants arm kernels compiled with frame pointers or stack unwinding.
 # If you know what you are doing and are willing to live without stack
 # traces, you can get a slightly smaller kernel by setting this option to
 # n, but then RMK will have to kill you ;).
 config FRAME_POINTER
 	bool
-	default y
+	default y if !ARM_UNWIND
 	help
 	  If you say N here, the resulting kernel will be slightly smaller and
-	  faster. However, when a problem occurs with the kernel, the
-	  information that is reported is severely limited. Most people
-	  should say Y here.
+	  faster. However, if neither FRAME_POINTER nor ARM_UNWIND are enabled,
+	  when a problem occurs with the kernel, the information that is
+	  reported is severely limited.
+
+config ARM_UNWIND
+	bool "Enable stack unwinding support"
+	depends on AEABI && EXPERIMENTAL
+	default y
+	help
+	  This option enables stack unwinding support in the kernel
+	  using the information automatically generated by the
+	  compiler. The resulting kernel image is slightly bigger but
+	  the performance is not affected. Currently, this feature
+	  only works with EABI compilers. If unsure say Y.
 
 config DEBUG_USER
 	bool "Verbose user fault messages"