tracing/kprobes: Add short documentation for HAVE_REGS_AND_STACK_ACCESS_API

So that arch developers know how to implement it without the
need to dig into changelogs.

Reported-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: "David S . Miller" <davem@davemloft.net>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20100218132521.GB2406@osiris.boeblingen.de.ibm.com>
[added reference to ptrace.h in the config help]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/arch/Kconfig b/arch/Kconfig
index 04e3aa7..50877ef 100644 (file)
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -123,6 +123,11 @@ config USE_GENERIC_SMP_HELPERS
 
 config HAVE_REGS_AND_STACK_ACCESS_API
        bool
+       help
+         This symbol should be selected by an architecure if it supports
+         the API needed to access registers and stack entries from pt_regs,
+         declared in asm/ptrace.h
+         For example the kprobes-based event tracer needs this API.
 
 config HAVE_CLK
        bool