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diff --git a/loader/LoaderAndLayerInterface.md b/loader/LoaderAndLayerInterface.md index ce8caaf9..cf11c78f 100644 --- a/loader/LoaderAndLayerInterface.md +++ b/loader/LoaderAndLayerInterface.md @@ -1,51 +1,51 @@ # Architecture of the Vulkan Loader Interfaces ## Table of Contents - * [Overview](#overview) - * [Who Should Read This Document](#who-should-read-this-document) - * [The Loader](#the-loader) - * [Layers](#layers) - * [Installable Client Drivers](#installable-client-drivers) - * [Instance Versus Device](#instance-versus-device) - * [Dispatch Tables and Call Chains](#dispatch-tables-and-call-chains) - - * [Application Interface to the Loader](#application-interface-to-the-loader) - * [Interfacing with Vulkan Functions](#interfacing-with-vulkan-functions) - * [Application Layer Usage](#application-layer-usage) - * [Application Usage of Extensions](#application-usage-of-extensions) - - * [Loader and Layer Interface](#loader-and-layer-interface) - * [Layer Discovery](#layer-discovery) - * [Layer Version Negotiation](#layer-version-negotiation) - * [Layer Call Chains and Distributed Dispatch](#layer-call-chains-and-distributed-dispatch) - * [Layer Unknown Physical Device Extensions](#layer-unknown-physical-device-extensions) - * [Layer Intercept Requirements](#layer-intercept-requirements) - * [Distributed Dispatching Requirements](#distributed-dispatching-requirements) - * [Layer Conventions and Rules](#layer-conventions-and-rules) - * [Layer Dispatch Initialization](#layer-dispatch-initialization) - * [Example Code for CreateInstance](#example-code-for-createinstance) - * [Example Code for CreateDevice](#example-code-for-createdevice) - * [Special Considerations](#special-considerations) - * [Layer Manifest File Format](#layer-manifest-file-format) - * [Layer Library Versions](#layer-library-versions) - - * [Vulkan Installable Client Driver interface with the loader](#vulkan-installable-client-driver-interface-with-the-loader) - * [ICD Discovery](#icd-discovery) - * [ICD Manifest File Format](#icd-manifest-file-format) - * [ICD Vulkan Entry-Point Discovery](#icd-vulkan-entry-point-discovery) - * [ICD Unknown Physical Device Extensions](#icd-unknown-physical-device-extensions) - * [ICD Dispatchable Object Creation](#icd-dispatchable-object-creation) - * [Handling KHR Surface Objects in WSI Extensions](#handling-khr-surface-objects-in-wsi-extensions) - * [Loader and ICD Interface Negotiation](#loader-and-icd-interface-negotiation) - * [Glossary of Terms](#glossary-of-terms) + * [Overview](#overview) + * [Who Should Read This Document](#who-should-read-this-document) + * [The Loader](#the-loader) + * [Layers](#layers) + * [Installable Client Drivers](#installable-client-drivers) + * [Instance Versus Device](#instance-versus-device) + * [Dispatch Tables and Call Chains](#dispatch-tables-and-call-chains) + + * [Application Interface to the Loader](#application-interface-to-the-loader) + * [Interfacing with Vulkan Functions](#interfacing-with-vulkan-functions) + * [Application Layer Usage](#application-layer-usage) + * [Application Usage of Extensions](#application-usage-of-extensions) + + * [Loader and Layer Interface](#loader-and-layer-interface) + * [Layer Discovery](#layer-discovery) + * [Layer Version Negotiation](#layer-version-negotiation) + * [Layer Call Chains and Distributed Dispatch](#layer-call-chains-and-distributed-dispatch) + * [Layer Unknown Physical Device Extensions](#layer-unknown-physical-device-extensions) + * [Layer Intercept Requirements](#layer-intercept-requirements) + * [Distributed Dispatching Requirements](#distributed-dispatching-requirements) + * [Layer Conventions and Rules](#layer-conventions-and-rules) + * [Layer Dispatch Initialization](#layer-dispatch-initialization) + * [Example Code for CreateInstance](#example-code-for-createinstance) + * [Example Code for CreateDevice](#example-code-for-createdevice) + * [Special Considerations](#special-considerations) + * [Layer Manifest File Format](#layer-manifest-file-format) + * [Layer Library Versions](#layer-library-versions) + + * [Vulkan Installable Client Driver interface with the loader](#vulkan-installable-client-driver-interface-with-the-loader) + * [ICD Discovery](#icd-discovery) + * [ICD Manifest File Format](#icd-manifest-file-format) + * [ICD Vulkan Entry-Point Discovery](#icd-vulkan-entry-point-discovery) + * [ICD Unknown Physical Device Extensions](#icd-unknown-physical-device-extensions) + * [ICD Dispatchable Object Creation](#icd-dispatchable-object-creation) + * [Handling KHR Surface Objects in WSI Extensions](#handling-khr-surface-objects-in-wsi-extensions) + * [Loader and ICD Interface Negotiation](#loader-and-icd-interface-negotiation) + * [Glossary of Terms](#glossary-of-terms) ## Overview Vulkan is a layered architecture, made up of the following elements: - * The Vulkan Application - * [The Vulkan Loader](#the-loader) - * [Vulkan Layers](#layers) - * [Installable Client Drivers (ICDs)](#installable-client-drivers) + * The Vulkan Application + * [The Vulkan Loader](#the-loader) + * [Vulkan Layers](#layers) + * [Installable Client Drivers (ICDs)](#installable-client-drivers)  @@ -263,20 +263,23 @@ because they deal with only a single device and the ICD can always be the In this section we'll discuss how an application interacts with the loader, including: - * [Interfacing with Vulkan Functions](#interfacing-with-vulkan-functions) - * [Vulkan Direct Exports](#vulkan-direct-exports) - * [Indirectly Linking to the Loader](#indirectly-linking-to-the-loader) - * [Best Application Performance Setup](#best-application-performance-setup) - * [ABI Versioning](#abi-versioning) - * [Application Layer Usage](#application-layer-usage) - * [Implicit vs Explicit Layers](#implicit-vs-explicit-layers) - * [Forcing Layer Source Folders](#forcing-layer-source-folders) - * [Forcing Layers to be Enabled](#forcing-layers-to-be-enabled) - * [Overall Layer Ordering](#overall-layer-ordering) - * [Application Usage of Extensions](#application-usage-of-extensions) - * [Instance and Device Extensions](#instance-and-device-extensions) - * [WSI Extensions](#wsi-extensions) - * [Unknown Extensions](#unknown-extensions) + * [Interfacing with Vulkan Functions](#interfacing-with-vulkan-functions) + * [Vulkan Direct Exports](#vulkan-direct-exports) + * [Directly Linking to the Loader](#directly-linking-to-the-loader) + * [Dynamic Linking](#dynamic-linking) + * [Static Linking](#static-linking) + * [Indirectly Linking to the Loader](#indirectly-linking-to-the-loader) + * [Best Application Performance Setup](#best-application-performance-setup) + * [ABI Versioning](#abi-versioning) + * [Application Layer Usage](#application-layer-usage) + * [Implicit vs Explicit Layers](#implicit-vs-explicit-layers) + * [Forcing Layer Source Folders](#forcing-layer-source-folders) + * [Forcing Layers to be Enabled](#forcing-layers-to-be-enabled) + * [Overall Layer Ordering](#overall-layer-ordering) + * [Application Usage of Extensions](#application-usage-of-extensions) + * [Instance and Device Extensions](#instance-and-device-extensions) + * [WSI Extensions](#wsi-extensions) + * [Unknown Extensions](#unknown-extensions) #### Interfacing with Vulkan Functions @@ -293,6 +296,36 @@ links directly to the loader library in this way, the Vulkan calls are simple object they are given. +##### Directly Linking to the Loader + +###### Dynamic Linking +The loader is ordinarily distributed as a dynamic library (.dll on Windows or +.so on Linux) which gets installed to the system path for dynamic libraries. +Linking to the dynamic library is generally the preferred method of linking to +the loader, as doing so allows the loader to be updated for bug fixes and +improvements. Furthermore, the dynamic library is generally installed to Windows +systems as part of driver installation and is generally provided on Linux +through the system package manager. This means that applications can usually +expect a copy of the loader to be present on a system. If applications want to +be completely sure that a loader is present, they can include a loader or +runtime installer with their application. + +###### Static Linking +The loader can also be used as a static library (this is shipped in the +Windows SDK as `VKstatic.1.lib`). Linking to the static loader means that the +user does not need to have a Vulkan runtime installed, and it also guarantees +that your application will use a specific version of the loader. However, there +are several downsides to this approach: + + - The static library can never be updated without re-linking the application + - This opens up the possibility that two included libraries could contain + different versions of the loader + - This could potentially cause conflicts between the different loader versions + +As a result, it is recommended that users prefer linking to the .dll and +.so versions of the loader. + + ##### Indirectly Linking to the Loader Applications are not required to link directly to the loader library, instead they can use the appropriate platform specific dynamic symbol lookup on the @@ -719,31 +752,31 @@ loader's filtering out of instance extension names. ## Loader and Layer Interface In this section we'll discuss how the loader interacts with layers, including: - * [Layer Discovery](#layer-discovery) - * [Layer Manifest File Usage](#layer-manifest-file-usage) - * [Android Layer Discovery](#android-layer-discovery) - * [Windows Layer Discovery](#windows-layer-discovery) - * [Linux Layer Discovery](#linux-layer-discovery) - * [Layer Version Negotiation](#layer-version-negotiation) - * [Layer Call Chains and Distributed Dispatch](#layer-call-chains-and-distributed-dispatch) - * [Layer Unknown Physical Device Extensions](#layer-unknown-physical-device-extensions) - * [Layer Intercept Requirements](#layer-intercept-requirements) - * [Distributed Dispatching Requirements](#distributed-dispatching-requirements) - * [Layer Conventions and Rules](#layer-conventions-and-rules) - * [Layer Dispatch Initialization](#layer-dispatch-initialization) - * [Example Code for CreateInstance](#example-code-for-createinstance) - * [Example Code for CreateDevice](#example-code-for-createdevice) - * [Special Considerations](#special-considerations) - * [Associating Private Data with Vulkan Objects Within a Layer](#associating-private-data-with-vulkan-objects-within-a-layer) - * [Wrapping](#wrapping) - * [Hash Maps](#hash-maps) - * [Creating New Dispatchable Objects](#creating-new-dispatchable-objects) - * [Layer Manifest File Format](#layer-manifest-file-format) - * [Layer Manifest File Version History](#layer-manifest-file-version-history) - * [Layer Library Versions](#layer-library-versions) - * [Layer Library API Version 2](#layer-library-api-version-2) - * [Layer Library API Version 1](#layer-library-api-version-1) - * [Layer Library API Version 0](#layer-library-api-version-0) + * [Layer Discovery](#layer-discovery) + * [Layer Manifest File Usage](#layer-manifest-file-usage) + * [Android Layer Discovery](#android-layer-discovery) + * [Windows Layer Discovery](#windows-layer-discovery) + * [Linux Layer Discovery](#linux-layer-discovery) + * [Layer Version Negotiation](#layer-version-negotiation) + * [Layer Call Chains and Distributed Dispatch](#layer-call-chains-and-distributed-dispatch) + * [Layer Unknown Physical Device Extensions](#layer-unknown-physical-device-extensions) + * [Layer Intercept Requirements](#layer-intercept-requirements) + * [Distributed Dispatching Requirements](#distributed-dispatching-requirements) + * [Layer Conventions and Rules](#layer-conventions-and-rules) + * [Layer Dispatch Initialization](#layer-dispatch-initialization) + * [Example Code for CreateInstance](#example-code-for-createinstance) + * [Example Code for CreateDevice](#example-code-for-createdevice) + * [Special Considerations](#special-considerations) + * [Associating Private Data with Vulkan Objects Within a Layer](#associating-private-data-with-vulkan-objects-within-a-layer) + * [Wrapping](#wrapping) + * [Hash Maps](#hash-maps) + * [Creating New Dispatchable Objects](#creating-new-dispatchable-objects) + * [Layer Manifest File Format](#layer-manifest-file-format) + * [Layer Manifest File Version History](#layer-manifest-file-version-history) + * [Layer Library Versions](#layer-library-versions) + * [Layer Library API Version 2](#layer-library-api-version-2) + * [Layer Library API Version 1](#layer-library-api-version-1) + * [Layer Library API Version 0](#layer-library-api-version-0) @@ -1017,17 +1050,17 @@ extension entry-points. In this way, it compares "pName" to every physical device function supported in the layer. The following rules apply: - * If it is the name of a physical device function supported by the layer, the + * If it is the name of a physical device function supported by the layer, the pointer to the layer's corresponding function should be returned. - * If it is the name of a valid function which is **not** a physical device + * If it is the name of a valid function which is **not** a physical device function (i.e. an Instance, Device, or other function implemented by the layer), then the value of NULL should be returned. - * We don’t call down since we know the command is not a physical device + * We don’t call down since we know the command is not a physical device extension). - * If the layer has no idea what this function is, it should call down the layer + * If the layer has no idea what this function is, it should call down the layer chain to the next `vk_layerGetPhysicalDeviceProcAddr` call. - * This can be retrieved in one of two ways: - * During `vkCreateInstance`, it is passed to a layer in the + * This can be retrieved in one of two ways: + * During `vkCreateInstance`, it is passed to a layer in the chain information passed to a layer in the `VkLayerInstanceCreateInfo` structure. * Use `get_chain_info()` to get the pointer to the @@ -1036,7 +1069,7 @@ structure. chain_info->u.pLayerInfo->pfnNextGetPhysicalDeviceProcAddr * See [Example Code for CreateInstance](#example-code-for-createinstance) - * Using the next layer’s `GetInstanceProcAddr` function to query for + * Using the next layer’s `GetInstanceProcAddr` function to query for `vk_layerGetPhysicalDeviceProcAddr`. This support is optional and should not be considered a requirement. This is @@ -1077,39 +1110,39 @@ attempting to use the commands. #### Layer Intercept Requirements - * Layers intercept a Vulkan function by defining a C/C++ function with + * Layers intercept a Vulkan function by defining a C/C++ function with signature **identical** to the Vulkan API for that function. - * A layer **must intercept at least** `vkGetInstanceProcAddr` and + * A layer **must intercept at least** `vkGetInstanceProcAddr` and `vkCreateInstance` to participate in the instance call chain. - * A layer **may also intercept** `vkGetDeviceProcAddr` and `vkCreateDevice` + * A layer **may also intercept** `vkGetDeviceProcAddr` and `vkCreateDevice` to participate in the device call chain. - * For any Vulkan function a layer intercepts which has a non-void return value, + * For any Vulkan function a layer intercepts which has a non-void return value, **an appropriate value must be returned** by the layer intercept function. - * Most functions a layer intercepts **should call down the chain** to the + * Most functions a layer intercepts **should call down the chain** to the corresponding Vulkan function in the next entity. - * The common behavior for a layer is to intercept a call, perform some + * The common behavior for a layer is to intercept a call, perform some behavior, then pass it down to the next entity. - * If you don't pass the information down, undefined behavior may occur. - * This is because the function will not be received by layers further down + * If you don't pass the information down, undefined behavior may occur. + * This is because the function will not be received by layers further down the chain, or any ICDs. - * One function that **must never call down the chain** is: - * `vkNegotiateLoaderLayerInterfaceVersion` - * Three common functions that **may not call down the chain** are: - * `vkGetInstanceProcAddr` - * `vkGetDeviceProcAddr` - * `vk_layerGetPhysicalDeviceProcAddr` - * These functions only call down the chain for Vulkan functions that they + * One function that **must never call down the chain** is: + * `vkNegotiateLoaderLayerInterfaceVersion` + * Three common functions that **may not call down the chain** are: + * `vkGetInstanceProcAddr` + * `vkGetDeviceProcAddr` + * `vk_layerGetPhysicalDeviceProcAddr` + * These functions only call down the chain for Vulkan functions that they do not intercept. - * Layer intercept functions **may insert extra calls** to Vulkan functions in + * Layer intercept functions **may insert extra calls** to Vulkan functions in addition to the intercept. - * For example, a layer intercepting `vkQueueSubmit` may want to add a call to + * For example, a layer intercepting `vkQueueSubmit` may want to add a call to `vkQueueWaitIdle` after calling down the chain for `vkQueueSubmit`. - * This would result in two calls down the chain: First a call down the + * This would result in two calls down the chain: First a call down the `vkQueueSubmit` chain, followed by a call down the `vkQueueWaitIdle` chain. - * Any additional calls inserted by a layer must be on the same chain - * If the function is a device function, only other device functions should + * Any additional calls inserted by a layer must be on the same chain + * If the function is a device function, only other device functions should be added. - * Likewise, if the function is an instance function, only other instance + * Likewise, if the function is an instance function, only other instance functions should be added. @@ -1117,9 +1150,9 @@ functions should be added. - For each entry-point a layer intercepts, it must keep track of the entry point residing in the next entity in the chain it will call down into. - * In other words, the layer must have a list of pointers to functions of the + * In other words, the layer must have a list of pointers to functions of the appropriate type to call into the next entity. - * This can be implemented in various ways but + * This can be implemented in various ways but for clarity, will be referred to as a dispatch table. - A layer can use the `VkLayerDispatchTable` structure as a device dispatch table (see include/vulkan/vk_layer.h). @@ -1159,37 +1192,37 @@ always enabled. That will allow applications to include the layer's memory usage. Additional rules include: - - `vkEnumerateInstanceLayerProperties` **must** enumerate and **only** + - `vkEnumerateInstanceLayerProperties` **must** enumerate and **only** enumerate the layer itself. - - `vkEnumerateInstanceExtensionProperties` **must** handle the case where + - `vkEnumerateInstanceExtensionProperties` **must** handle the case where `pLayerName` is itself. - - It **must** return `VK_ERROR_LAYER_NOT_PRESENT` otherwise, including when + - It **must** return `VK_ERROR_LAYER_NOT_PRESENT` otherwise, including when `pLayerName` is `NULL`. - - `vkEnumerateDeviceLayerProperties` **is deprecated and may be omitted**. - - Using this will result in undefined behavior. - - `vkEnumerateDeviceExtensionProperties` **must** handle the case where + - `vkEnumerateDeviceLayerProperties` **is deprecated and may be omitted**. + - Using this will result in undefined behavior. + - `vkEnumerateDeviceExtensionProperties` **must** handle the case where `pLayerName` is itself. - - In other cases, it should normally chain to other layers. - - `vkCreateInstance` **must not** generate an error for unrecognized layer + - In other cases, it should normally chain to other layers. + - `vkCreateInstance` **must not** generate an error for unrecognized layer names and extension names. - - It may assume the layer names and extension names have been validated. - - `vkGetInstanceProcAddr` intercepts a Vulkan function by returning a local + - It may assume the layer names and extension names have been validated. + - `vkGetInstanceProcAddr` intercepts a Vulkan function by returning a local entry-point - - Otherwise it returns the value obtained by calling down the instance call + - Otherwise it returns the value obtained by calling down the instance call chain. - - `vkGetDeviceProcAddr` intercepts a Vulkan function by returning a local + - `vkGetDeviceProcAddr` intercepts a Vulkan function by returning a local entry-point - - Otherwise it returns the value obtained by calling down the device call + - Otherwise it returns the value obtained by calling down the device call chain. - - These additional functions must be intercepted if the layer implements + - These additional functions must be intercepted if the layer implements device-level call chaining: - - `vkGetDeviceProcAddr` - - `vkCreateDevice`(only required for any device-level chaining) - - **NOTE:** older layer libraries may expect that `vkGetInstanceProcAddr` + - `vkGetDeviceProcAddr` + - `vkCreateDevice`(only required for any device-level chaining) + - **NOTE:** older layer libraries may expect that `vkGetInstanceProcAddr` ignore `instance` when `pName` is `vkCreateDevice`. - - The specification **requires** `NULL` to be returned from + - The specification **requires** `NULL` to be returned from `vkGetInstanceProcAddr` and `vkGetDeviceProcAddr` for disabled functions. - - A layer may return `NULL` itself or rely on the following layers to do so. + - A layer may return `NULL` itself or rely on the following layers to do so. #### Layer Dispatch Initialization @@ -1641,24 +1674,24 @@ A layer library supporting interface version 0 must define and export these introspection functions, unrelated to any Vulkan function despite the names, signatures, and other similarities: - - `vkEnumerateInstanceLayerProperties` enumerates all layers in a layer +- `vkEnumerateInstanceLayerProperties` enumerates all layers in a layer library. - This function never fails. - When a layer library contains only one layer, this function may be an alias to the layer's `vkEnumerateInstanceLayerProperties`. - - `vkEnumerateInstanceExtensionProperties` enumerates instance extensions of +- `vkEnumerateInstanceExtensionProperties` enumerates instance extensions of layers in a layer library. - "pLayerName" is always a valid layer name. - This function never fails. - When a layer library contains only one layer, this function may be an alias to the layer's `vkEnumerateInstanceExtensionProperties`. - - `vkEnumerateDeviceLayerProperties` enumerates a subset (can be full, +- `vkEnumerateDeviceLayerProperties` enumerates a subset (can be full, proper, or empty subset) of layers in a layer library. - "physicalDevice" is always `VK_NULL_HANDLE`. - This function never fails. - If a layer is not enumerated by this function, it will not participate in device function interception. - - `vkEnumerateDeviceExtensionProperties` enumerates device extensions of +- `vkEnumerateDeviceExtensionProperties` enumerates device extensions of layers in a layer library. - "physicalDevice" is always `VK_NULL_HANDLE`. - "pLayerName" is always a valid layer name. @@ -1667,13 +1700,13 @@ library. It must also define and export these functions once for each layer in the library: - - `<layerName>GetInstanceProcAddr(instance, pName)` behaves identically to a +- `<layerName>GetInstanceProcAddr(instance, pName)` behaves identically to a layer's vkGetInstanceProcAddr except it is exported. When a layer library contains only one layer, this function may alternatively be named `vkGetInstanceProcAddr`. - - `<layerName>GetDeviceProcAddr` behaves identically to a layer's +- `<layerName>GetDeviceProcAddr` behaves identically to a layer's vkGetDeviceProcAddr except it is exported. When a layer library contains only one layer, this function may @@ -1692,28 +1725,28 @@ not to export any functions. This section discusses the various requirements for the loader and a Vulkan ICD to properly hand-shake. - * [ICD Discovery](#icd-discovery) - * [ICD Manifest File Usage](#icd-manifest-file-usage) - * [ICD Discovery on Windows](#icd-discovery-on-windows) - * [ICD Discovery on Linux](#icd-discovery-on-linux) - * [Using Pre-Production ICDs on Windows and Linux](#using-pre-production-icds-on-windows-and-linux) - * [ICD Discovery on Android](#icd-discovery-on-android) - * [ICD Manifest File Format](#icd-manifest-file-format) - * [ICD Manifest File Versions](#icd-manifest-file-versions) - * [ICD Manifest File Version 1.0.0](#icd-manifest-file-version-1.0.0) - * [ICD Vulkan Entry-Point Discovery](#icd-vulkan-entry-point-discovery) - * [ICD Unknown Physical Device Extensions](#icd-unknown-physical-device-extensions) - * [ICD Dispatchable Object Creation](#icd-dispatchable-object-creation) - * [Handling KHR Surface Objects in WSI Extensions](#handling-khr-surface-objects-in-wsi-extensions) - * [Loader and ICD Interface Negotiation](#loader-and-icd-interface-negotiation) - * [Windows and Linux ICD Negotiation](#windows-and-linux-icd-negotiation) - * [Version Negotiation Between Loader and ICDs](#version-negotiation-between-loader-and-icds) - * [Interfacing With Legacy ICDs or Loader](#interfacing-with-legacy-icds-or-loader] - * [Loader Version 4 Interface Requirements](#loader-version-4-interface-requirements) - * [Loader Version 3 Interface Requirements](#loader-version-3-interface-requirements) - * [Loader Version 2 Interface Requirements](#loader-version-2-interface-requirements) - * [Loader Versions 0 and 1 Interface Requirements](#loader-versions-0-and-1-interface-requirements) - * [Android ICD Negotiation](#android-icd-negotiation) + * [ICD Discovery](#icd-discovery) + * [ICD Manifest File Usage](#icd-manifest-file-usage) + * [ICD Discovery on Windows](#icd-discovery-on-windows) + * [ICD Discovery on Linux](#icd-discovery-on-linux) + * [Using Pre-Production ICDs on Windows and Linux](#using-pre-production-icds-on-windows-and-linux) + * [ICD Discovery on Android](#icd-discovery-on-android) + * [ICD Manifest File Format](#icd-manifest-file-format) + * [ICD Manifest File Versions](#icd-manifest-file-versions) + * [ICD Manifest File Version 1.0.0](#icd-manifest-file-version-1.0.0) + * [ICD Vulkan Entry-Point Discovery](#icd-vulkan-entry-point-discovery) + * [ICD Unknown Physical Device Extensions](#icd-unknown-physical-device-extensions) + * [ICD Dispatchable Object Creation](#icd-dispatchable-object-creation) + * [Handling KHR Surface Objects in WSI Extensions](#handling-khr-surface-objects-in-wsi-extensions) + * [Loader and ICD Interface Negotiation](#loader-and-icd-interface-negotiation) + * [Windows and Linux ICD Negotiation](#windows-and-linux-icd-negotiation) + * [Version Negotiation Between Loader and ICDs](#version-negotiation-between-loader-and-icds) + * [Interfacing With Legacy ICDs or Loader](#interfacing-with-legacy-icds-or-loader) + * [Loader Version 4 Interface Requirements](#loader-version-4-interface-requirements) + * [Loader Version 3 Interface Requirements](#loader-version-3-interface-requirements) + * [Loader Version 2 Interface Requirements](#loader-version-2-interface-requirements) + * [Loader Versions 0 and 1 Interface Requirements](#loader-versions-0-and-1-interface-requirements) + * [Android ICD Negotiation](#android-icd-negotiation) ### ICD Discovery @@ -1974,12 +2007,12 @@ extension entry-points. In this way, it compares "pName" to every physical device function supported in the ICD. The following rules apply: - * If it is the name of a physical device function supported by the ICD, the +* If it is the name of a physical device function supported by the ICD, the pointer to the ICD's corresponding function should be returned. - * If it is the name of a valid function which is **not** a physical device +* If it is the name of a valid function which is **not** a physical device function (i.e. an Instance, Device, or other function implemented by the ICD), then the value of NULL should be returned. - * If the ICD has no idea what this function is, it should return NULL. +* If the ICD has no idea what this function is, it should return NULL. This support is optional and should not be considered a requirement. This is only required if an ICD intends to support some functionality not directly |