layers: Update docs for default dbg msg callbacks

Change-Id: Ic1f192ea7c95762d7e53f091cc9f0ea55be96c04

2 files changed, 15 insertions, 8 deletions

diff --git a/layers/README.md b/layers/README.md
index e2cea90d..d3eecbf1 100644
--- a/layers/README.md
+++ b/layers/README.md
@@ -20,12 +20,14 @@ VkDevice, VkCommandBuffer, and VkQueue.
 vkXXXXGetProcAddr is used internally by the Layers and Loader to initialize dispatch tables.
 Layers can also be activated via the VK_INSTANCE_LAYERS environment variable.
 
-All validation layers work with the DEBUG_REPORT extension to provide the application or user with
-validation feedback. When a validation layer is enabled, it will look at the vk_layer_settings.txt
-file to determine its behavior. Such as outputing to a file, stdout or debug output (Windows). An
-application can also register callback functions via the DEBUG_REPORT extension to receive callbacks
-when the requested validation events happen. Application callbacks happen regardless of the
-settings in the vk_layer_settings.txt file.
+All validation layers work with the DEBUG_REPORT extension to provide validation feedback.
+When a validation layer is enabled, it will look for a vk_layer_settings.txt file to define
+its loggin behavior, which can include sending output to a file, stdout, or debug output (Windows).
+Applications can also register debug callback functions via the DEBUG_REPORT extension to receive
+callbacks when validation events occur. Application callbacks are independent of settings in a
+vk_layer_settings.txt file which will be carried out separately. If no vk_layer_settings.txt
+file is present and no application callbacks are registered, error messages will be output
+through default logging callbacks.
 
 ### Layer library example code
 
diff --git a/layers/vk_layer_settings.txt b/layers/vk_layer_settings.txt
index d83b8326..aef2f311 100644
--- a/layers/vk_layer_settings.txt
+++ b/layers/vk_layer_settings.txt
@@ -1,4 +1,5 @@
 # This is an example vk_layer_settings.txt file.
+#
 #  This file allows for per-layer settings which can dynamically affect layer
 #  behavior. Comments in this file are denoted with the "#" char.
 #  Settings lines are of the form "<LayerIdentifier>.<SettingName> = <SettingValue>"
@@ -26,6 +27,9 @@
 #    VK_DBG_LAYER_ACTION_CALLBACK - Call user defined callback function(s) that
 #       have been registered via the VK_EXT_LUNARG_debug_report extension. Since
 #       app must register callback, this is a NOOP for the settings file.
+#    VK_DBG_LAYER_DEBUG_OUTPUT [Windows only] - Log a txt message using the Windows
+#       OutputDebugString function -- messages will show up in Visual Studio output
+#       window, for instance.
 #    VK_DBG_LAYER_ACTION_BREAK - Trigger a breakpoint.
 #
 #   REPORT_FLAGS:
@@ -33,8 +37,9 @@
 #   <LayerIdentifier>.report_flags : This is a comma-delineated list of options telling
 #    the layer what types of messages it should report back. Options are:
 #    info - Report informational messages
-#    warn - Report warnings of using the API in an unrecommended manner which may
-#       also lead to undefined behavior
+#    warn - Report warnings from using the API in a manner which may lead to undefined
+#           behavior or to warn the user of common trouble spots. A warning does NOT
+#           necessarily signify illegal application behavior.
 #    perf - Report using the API in a way that may cause suboptimal performance
 #    error - Report errors in API usage
 #    debug - For layer development. Report messages for debugging layer behavior