Dynamic Debug: Introduce ddebug_query= boot parameter

Dynamic debug lacks the ability to enable debug messages at boot time.
One could patch initramfs or service startup scripts to write to
/sys/../dynamic_debug/control, but this sucks.

This patch makes it possible to pass a query in the same format one can
write to /sys/../dynamic_debug/control via boot param.
When dynamic debug gets initialized, this query will automatically be
applied.


Signed-off-by: Thomas Renninger <trenn@suse.de>
Acked-by: jbaron@redhat.com
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 8dd7248..3d854c9 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -43,10 +43,11 @@
 	AVR32	AVR32 architecture is enabled.
 	AX25	Appropriate AX.25 support is enabled.
 	BLACKFIN Blackfin architecture is enabled.
-	DRM	Direct Rendering Management support is enabled.
 	EDD	BIOS Enhanced Disk Drive Services (EDD) is enabled
 	EFI	EFI Partitioning (GPT) is enabled
 	EIDE	EIDE/ATAPI support is enabled.
+	DRM	Direct Rendering Management support is enabled.
+	DYNAMIC_DEBUG Build in debug messages and enable them at runtime
 	FB	The frame buffer device is enabled.
 	GCOV	GCOV profiling is enabled.
 	HW	Appropriate hardware is enabled.
@@ -570,6 +571,10 @@
 			Format: <port#>,<type>
 			See also Documentation/input/joystick-parport.txt
 
+	ddebug_query=   [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
+			time. See Documentation/dynamic-debug-howto.txt for
+			details.
+
 	debug		[KNL] Enable kernel debugging (events log level).
 
 	debug_locks_verbose=