khronos_validation_layer.md

VK_LAYER_KHRONOS_validation

Vulkan is an Explicit API, enabling direct control over how GPUs actually work. By design, minimal error checking is done inside a Vulkan driver - applications have full control and responsibility for correct operation. Any errors in Vulkan usage can result in unexpected behavior or even a crash. The VK_LAYER_KHRONOS_validation layer can be used to to assist developers in isolating incorrect usage, and in verifying that applications correctly use the API.

Configuring the Validation Layer

There are 4 ways to configure the settings: vkconfig, application defined, vk_layer_settings.txt, environment variables

VkConfig

We suggest people to use VkConfig.

The GUI comes with the SDK, and takes the VkLayer_khronos_validation.json file and does everything for you!

Application Defined

The application can now use the VK_EXT_layer_settings extension to do everything at vkCreateInstance time. (Don't worry, we implement the extension, so it will be supported 100% of the time!).

// Example how to turn on verbose mode for DebugPrintf
const VkBool32 verbose_value = true;
const VkLayerSettingEXT layer_setting = {"VK_LAYER_KHRONOS_validation", "printf_verbose", VK_LAYER_SETTING_TYPE_BOOL32_EXT, 1, &verbose_value};
VkLayerSettingsCreateInfoEXT layer_settings_create_info = {VK_STRUCTURE_TYPE_LAYER_SETTINGS_CREATE_INFO_EXT, nullptr, 1, &layer_setting};

VkInstanceCreateInfo instance_ci = GetYourCreateInfo();
instance_ci.pNext = &layer_settings_create_info;

vk_layer_settings.txt

There is info elsewhere to describe this file, but the short answer is to set the VK_LAYER_SETTINGS_PATH like the following:

# windows
set VK_LAYER_SETTINGS_PATH=C:\path\to\vk_layer_settings.txt

# linux
export VK_LAYER_SETTINGS_PATH=/path/to/vk_layer_settings.txt

and it will set things for you in that file. We have a default example file you can start with.

Environment Variables

This is done for us via the vkuCreateLayerSettingSet call in the Vulkan-Utility-Libraries.

As an example, in our VkLayer_khronos_validation.json file you will find something like "key": "message_id_filter",.

From here you just need to adjust it the naming and prefix depending on your platform:

# Windows
set VK_LAYER_MESSAGE_ID_FILTER=VUID-VkInstanceCreateInfo-pNext-pNext

# Linux
export VK_LAYER_MESSAGE_ID_FILTER=VUID-VkInstanceCreateInfo-pNext-pNext

# Android
adb setprop debug.vulkan.khronos_validation.message_id_filter=VUID-VkInstanceCreateInfo-pNext-pNext

Layer Options

We suggest using VkConfig to discover the options, but the following is generated per SDK version

The options for this layer are specified in VkLayer_khronos_validation.json. The option details are in khronos_validation_layer.html.