Vulkan error vkCreateDevice : VK_ERROR_EXTENSION_NOT_PRESENT

Question

I am starting with Vulkan and I follow the Niko Kauppi's tutorial on Youtube.

I have an error when creating a device with vkCreateDevice, it returns VK_ERROR_EXTENSION_NOT_PRESENT

Here some part of my code:

1. The call to vkCreateDevice

   _gpu_count = 0;
   vkEnumeratePhysicalDevices(instance, &_gpu_count, nullptr);
   std::vector<VkPhysicalDevice> gpu_list(_gpu_count);
   vkEnumeratePhysicalDevices(instance, &_gpu_count, gpu_list.data());
   _gpu = gpu_list[0];
   
   vkGetPhysicalDeviceProperties(_gpu, &_gpu_properties);
   
   VkDeviceCreateInfo device_create_info = _CreateDeviceInfo();
   
   vulkanCheckError(vkCreateDevice(_gpu, &device_create_info, nullptr, &_device));
   

_gpu_count = 1 and _gpu_properties seems to recognize well my nvidia gpu (which is not up to date)

2. device_create_info

   VkDeviceCreateInfo _createDeviceInfo;
   
   _createDeviceInfo.sType = VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO;
   _createDeviceInfo.queueCreateInfoCount = 1;
   VkDeviceQueueCreateInfo _queueInfo = _CreateDeviceQueueInfo();
   _createDeviceInfo.pQueueCreateInfos = &_queueInfo;
   

I don't understand the meaning of the error: "A requested extension is not supported" according to Khronos' doc.

Thanks for your help

Answer 1

VK_ERROR_EXTENSION_NOT_PRESENT is returned when one of the extensions in [enabledExtensionCount, ppEnabledExtensionNames] vector you provided is not supported by the driver (as queried by vkEnumerateDeviceExtensionProperties()).

Extensions can also have dependencies, so VK_ERROR_EXTENSION_NOT_PRESENT is also returned when an extension dependency of extension in the list is missing there too.

If you want no device extensions, make sure enabledExtensionCount of VkDeviceCreateInfo is 0 (and not e.g. some uninitialized value).

I assume 2. is the whole body of _CreateDeviceInfo(), which would confirm the "uninitialized value" suspicion.

Usually though you would want a swapchain extension there to be able to render to screen directly.

Answer 2

First of all, make sure your VkDeviceCreateInfo is zero filled, otherwise it may carry garbage to your VkCreateDevice() call.

Add following line just after declaring your VkDeviceCreateInfo:

memset ( &_createDeviceInfo, 0, sizeof(VkDeviceCreateInfo)  );

Some extensions are absolutely necessary, as swapchain one.

To retrieve available extensions do this:

// Available extensions and layers names
const char* const* _ppExtensionNames = NULL;    
// get extension names
uint32 _extensionCount = 0;
vkEnumerateDeviceExtensionProperties( _gpu, NULL, &_extensionCount, NULL);
std::vector<const char *> extNames;
std::vector<VkExtensionProperties> extProps(_extensionCount);
vkEnumerateDeviceExtensionProperties(_gpu, NULL, &_extensionCount, extProps.data());
for (uint32_t i = 0; i < _extensionCount; i++) {
    extNames.push_back(extProps[i].extensionName);
}
 _ppExtensionNames = extNames.data();

Once you have all extension names in _ppExtensionNames, pass it to your deviceCreateInfo struct:

 VkDeviceCreateInfo  device_create_info ...
    [...]
    device_create_info.enabledExtensionCount = _extensionCount;
    device_create_info.ppEnabledExtensionNames = _ppExtensionNames;
    [...]
vulkanCheckError(vkCreateDevice(_gpu, &device_create_info, nullptr, &_device));

I hope it helps. Please double check above code, as I'm writing it by heart.