[PATCH] x86_64: x86_64 stack usage debugging

Applies to git & 2.6.17-rc6 after CONFIG_DEBUG_STACKOVERFLOW patch

uses same stack-zeroing mechanism as on i386 to discover maximum stack
excursions.

Signed-off-by: Eric Sandeen <sandeen@sgi.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug
index 087a048..1d92ab5 100644
--- a/arch/x86_64/Kconfig.debug
+++ b/arch/x86_64/Kconfig.debug
@@ -42,6 +42,15 @@
 	  This option will cause messages to be printed if free stack space
 	  drops below a certain limit.
 
+config DEBUG_STACK_USAGE
+        bool "Stack utilization instrumentation"
+        depends on DEBUG_KERNEL
+        help
+	  Enables the display of the minimum amount of free stack which each
+	  task has ever had available in the sysrq-T and sysrq-P debug output.
+
+	  This option will slow down process creation somewhat.
+
 #config X86_REMOTE_DEBUG
 #       bool "kgdb debugging stub"