Don't advertise anti lag if the PD doesn't support it

1 files changed, 15 insertions, 2 deletions

diff --git a/src/physical_device_context.hh b/src/physical_device_context.hh
index 291946f..9624faa 100644
--- a/src/physical_device_context.hh
+++ b/src/physical_device_context.hh
@@ -11,15 +11,28 @@ namespace low_latency {
 
 class PhysicalDeviceContext final : public Context {
   public:
+    // The extensions we need for our layer to function.
+    // If the PD doesn't support this then the layer shouldn't set the anti lag
+    // flag in VkGetPhysicalDevices2 (check this->supports_required_extensions).
+    static constexpr auto required_extensions = {
+        VK_KHR_SYNCHRONIZATION_2_EXTENSION_NAME,
+        VK_KHR_CALIBRATED_TIMESTAMPS_EXTENSION_NAME,
+        VK_EXT_HOST_QUERY_RESET_EXTENSION_NAME};
+
+  public:
     InstanceContext& instance;
 
     const VkPhysicalDevice physical_device;
-    
+
     std::unique_ptr<const VkPhysicalDeviceProperties> properties;
-    
+
     using queue_properties_t = std::vector<VkQueueFamilyProperties2>;
     std::unique_ptr<const queue_properties_t> queue_properties;
 
+    // Will be set to true in the constructor if the physical device supports
+    // everything we need to track gpu timing data.
+    bool supports_required_extensions = false;
+
   public:
     PhysicalDeviceContext(InstanceContext& instance_context,
                           const VkPhysicalDevice& physical_device);