// Copyright (c) 2015-2017 Khronos Group. This work is licensed under a // Creative Commons Attribution 4.0 International License; see // http://creativecommons.org/licenses/by/4.0/ [[commandbuffers]] = Command Buffers [open,refpage='VkCommandBuffer',desc='Opaque handle to a command buffer object',type='handles'] -- Command buffers are objects used to record commands which can: be subsequently submitted to a device queue for execution. There are two levels of command buffers - _primary command buffers_, which can: execute secondary command buffers, and which are submitted to queues, and _secondary command buffers_, which can: be executed by primary command buffers, and which are not directly submitted to queues. Command buffers are represented by sname:VkCommandBuffer handles: include::../api/handles/VkCommandBuffer.txt[] -- Recorded commands include commands to bind pipelines and descriptor sets to the command buffer, commands to modify dynamic state, commands to draw (for graphics rendering), commands to dispatch (for compute), commands to execute secondary command buffers (for primary command buffers only), commands to copy buffers and images, and other commands. [[commandbuffers-statereset]] Each command buffer manages state independently of other command buffers. There is no inheritance of state across primary and secondary command buffers, or between secondary command buffers. When a command buffer begins recording, all state in that command buffer is undefined. When secondary command buffer(s) are recorded to execute on a primary command buffer, the secondary command buffer inherits no state from the primary command buffer, and all state of the primary command buffer is undefined after an execute secondary command buffer command is recorded. There is one exception to this rule - if the primary command buffer is inside a render pass instance, then the render pass and subpass state is not disturbed by executing secondary command buffers. Whenever the state of a command buffer is undefined, the application must: set all relevant state on the command buffer before any state dependent commands such as draws and dispatches are recorded, otherwise the behavior of executing that command buffer is undefined. Unless otherwise specified, and without explicit synchronization, the various commands submitted to a queue via command buffers may: execute in arbitrary order relative to each other, and/or concurrently. Also, the memory side-effects of those commands may: not be directly visible to other commands without explicit memory dependencies. This is true within a command buffer, and across command buffers submitted to a given queue. See <> for information on <> and explicit synchronization between commands. [[commandbuffers-lifecycle]] == Command Buffer Lifecycle Each command buffer is always in one of the following states: Initial:: When a command buffer is <> is in the _initial state_. Some commands are able to _reset_ a command buffer, or a set of command buffers, back to this state from any of the executable, recording or invalid state. Command buffers in the initial state can: only be moved to the recording state, or freed. Recording:: flink:vkBeginCommandBuffer changes the state of a command buffer from the initial state to the _recording state_. Once a command buffer is in the recording state, vkCmd* commands can: be used to record to the command buffer. Executable:: flink:vkEndCommandBuffer ends the recording of a command buffer, and moves it from the recording state to the _executable state_. Executable command buffers can: be <>, reset, or <>. Pending:: <> of a command buffer changes the state of a command buffer from the executable state to the _pending state_. Whilst in the pending state, applications must: not attempt to modify the command buffer in any way - the device may: be processing the commands recorded to it. Once execution of a command buffer completes, the command buffer reverts back to the executable state. A <> command should: be used to detect when this occurs. Invalid:: Some operations, such as modifying or deleting a resource that was used in a command recorded to a command buffer, will transition the state of a command buffer into the _invalid state_. Command buffers in the invalid state can: only be reset, moved to the _recording state_, or freed. Any given command that operates on a command buffer has its own requirements on what state a command buffer must: be in, which are detailed in the valid usage constraints for that command. Resetting a command buffer is an operation that discards any previously recorded commands and puts a command buffer in the initial state. Resetting occurs as a result of flink:vkResetCommandBuffer or flink:vkResetCommandPool, or as part of flink:vkBeginCommandBuffer (which additionally puts the command buffer in the recording state). <> can: be recorded to a primary command buffer via flink:vkCmdExecuteCommands. This partially ties the lifecycle of the two command buffers together - if the primary is submitted to a queue, both the primary and any secondaries recorded to it move to the pending state. Once execution of the primary completes, so does any secondary recorded within it, and once all executions of each command buffer complete, they move to the executable state. If a secondary moves to any other state whilst it is recorded to another command buffer, the primary moves to the invalid state. A primary moving to any other state does not affect the state of the secondary. Resetting or freeing a primary command buffer removes the linkage to any secondary command buffers that were recorded to it. [[commandbuffers-pools]] == Command Pools [open,refpage='VkCommandPool',desc='Opaque handle to a command pool object',type='handles'] -- Command pools are opaque objects that command buffer memory is allocated from, and which allow the implementation to amortize the cost of resource creation across multiple command buffers. Command pools are externally synchronized, meaning that a command pool must: not be used concurrently in multiple threads. That includes use via recording commands on any command buffers allocated from the pool, as well as operations that allocate, free, and reset command buffers or the pool itself. Command pools are represented by sname:VkCommandPool handles: include::../api/handles/VkCommandPool.txt[] -- [open,refpage='vkCreateCommandPool',desc='Create a new command pool object',type='protos'] -- To create a command pool, call: include::../api/protos/vkCreateCommandPool.txt[] * pname:device is the logical device that creates the command pool. * pname:pCreateInfo contains information used to create the command pool. * pname:pAllocator controls host memory allocation as described in the <> chapter. * pname:pCommandPool points to a sname:VkCommandPool handle in which the created pool is returned. include::../validity/protos/vkCreateCommandPool.txt[] -- [open,refpage='VkCommandPoolCreateInfo',desc='Structure specifying parameters of a newly created command pool',type='structs'] -- The sname:VkCommandPoolCreateInfo structure is defined as: include::../api/structs/VkCommandPoolCreateInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitmask of elink:VkCommandPoolCreateFlagBits indicating usage behavior for the pool and command buffers allocated from it. * pname:queueFamilyIndex designates a queue family as described in section <>. All command buffers allocated from this command pool must: be submitted on queues from the same queue family. .Valid Usage **** * [[VUID-VkCommandPoolCreateInfo-queueFamilyIndex-00039]] pname:queueFamilyIndex must: be the index of a queue family available in the calling command's pname:device parameter **** include::../validity/structs/VkCommandPoolCreateInfo.txt[] -- [open,refpage='VkCommandPoolCreateFlagBits',desc='Bitmask specifying usage behavior for a command pool',type='enums'] -- Bits which can: be set in slink:VkCommandPoolCreateInfo::pname:flags to specify usage behavior for a command pool are: include::../api/enums/VkCommandPoolCreateFlagBits.txt[] * ename:VK_COMMAND_POOL_CREATE_TRANSIENT_BIT indicates that command buffers allocated from the pool will be short-lived, meaning that they will be reset or freed in a relatively short timeframe. This flag may: be used by the implementation to control memory allocation behavior within the pool. * ename:VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT allows any command buffer allocated from a pool to be individually reset to the <>; either by calling flink:vkResetCommandBuffer, or via the implicit reset when calling flink:vkBeginCommandBuffer. If this flag is not set on a pool, then fname:vkResetCommandBuffer must: not be called for any command buffer allocated from that pool. -- ifdef::VK_KHR_maintenance1[] [open,refpage='vkTrimCommandPoolKHR',desc='Trim a command pool',type='protos'] -- To trim a command pool, call: include::../api/protos/vkTrimCommandPoolKHR.txt[] * pname:device is the logical device that owns the command pool. * pname:commandPool is the command pool to trim. * pname:flags is reserved for future use. Trimming a command pool recycles unused memory from the command pool back to the system. Command buffers allocated from the pool are not affected by the command. [NOTE] .Note ==== This command provides applications with some control over the internal memory allocations used by command pools. Unused memory normally arises from command buffers that have been recorded and later reset, such that they are no longer using the memory. On reset, a command buffer can return memory to its command pool, but the only way to release memory from a command pool to the system requires calling flink:vkResetCommandPool, which cannot be executed while any command buffers from that pool are still in use. Subsequent recording operations into command buffers will re-use this memory but since total memory requirements fluctuate over time, unused memory can accumulate. In this situation, trimming a command pool may: be useful to return unused memory back to the system, returning the total outstanding memory allocated by the pool back to a more "average" value. Implementations utilize many internal allocation strategies that make it impossible to guarantee that all unused memory is released back to the system. For instance, an implementation of a command pool may: involve allocating memory in bulk from the system and sub-allocating from that memory. In such an implementation any live command buffer that holds a reference to a bulk allocation would prevent that allocation from being freed, even if only a small proportion of the bulk allocation is in use. In most cases trimming will result in a reduction in allocated but unused memory, but it does not guarantee the "ideal" behaviour. Trimming may: be an expensive operation, and should: not be called frequently. Trimming should: be treated as a way to relieve memory pressure after application-known points when there exists enough unused memory that the cost of trimming is "worth" it. ==== include::../validity/protos/vkTrimCommandPoolKHR.txt[] -- endif::VK_KHR_maintenance1[] [open,refpage='vkResetCommandPool',desc='Reset a command pool',type='protos'] -- To reset a command pool, call: include::../api/protos/vkResetCommandPool.txt[] * pname:device is the logical device that owns the command pool. * pname:commandPool is the command pool to reset. * pname:flags is a bitmask of elink:VkCommandPoolResetFlagBits controlling the reset operation. Resetting a command pool recycles all of the resources from all of the command buffers allocated from the command pool back to the command pool. All command buffers that have been allocated from the command pool are put in the <>. Any primary command buffer allocated from another slink:VkCommandPool that is in the <> and has a secondary command buffer allocated from pname:commandPool recorded into it, becomes <>. .Valid Usage **** * [[VUID-vkResetCommandPool-commandPool-00040]] All sname:VkCommandBuffer objects allocated from pname:commandPool must: not be in the <> **** include::../validity/protos/vkResetCommandPool.txt[] -- [open,refpage='VkCommandPoolResetFlagBits',desc='Bitmask controlling behavior of a command pool reset',type='enums'] -- Bits which can: be set in flink:vkResetCommandPool::pname:flags to control the reset operation are: include::../api/enums/VkCommandPoolResetFlagBits.txt[] * ename:VK_COMMAND_POOL_RESET_RELEASE_RESOURCES_BIT specifies that resetting a command pool recycles all of the resources from the command pool back to the system. -- [open,refpage='vkDestroyCommandPool',desc='Destroy a command pool object',type='protos'] -- To destroy a command pool, call: include::../api/protos/vkDestroyCommandPool.txt[] * pname:device is the logical device that destroys the command pool. * pname:commandPool is the handle of the command pool to destroy. * pname:pAllocator controls host memory allocation as described in the <> chapter. When a pool is destroyed, all command buffers allocated from the pool are <>. Any primary command buffer allocated from another slink:VkCommandPool that is in the <> and has a secondary command buffer allocated from pname:commandPool recorded into it, becomes <>. .Valid Usage **** * [[VUID-vkDestroyCommandPool-commandPool-00041]] All sname:VkCommandBuffer objects allocated from pname:commandPool must: not be in the <>. * [[VUID-vkDestroyCommandPool-commandPool-00042]] If sname:VkAllocationCallbacks were provided when pname:commandPool was created, a compatible set of callbacks must: be provided here * [[VUID-vkDestroyCommandPool-commandPool-00043]] If no sname:VkAllocationCallbacks were provided when pname:commandPool was created, pname:pAllocator must: be `NULL` **** include::../validity/protos/vkDestroyCommandPool.txt[] -- [[commandbuffer-allocation]] == Command Buffer Allocation and Management [open,refpage='vkAllocateCommandBuffers',desc='Allocate command buffers from an existing command pool',type='protos'] -- To allocate command buffers, call: include::../api/protos/vkAllocateCommandBuffers.txt[] * pname:device is the logical device that owns the command pool. * pname:pAllocateInfo is a pointer to an instance of the sname:VkCommandBufferAllocateInfo structure describing parameters of the allocation. * pname:pCommandBuffers is a pointer to an array of sname:VkCommandBuffer handles in which the resulting command buffer objects are returned. The array must: be at least the length specified by the pname:commandBufferCount member of pname:pAllocateInfo. Each allocated command buffer begins in the initial state. ifdef::VK_KHR_maintenance1[] fname:vkAllocateCommandBuffers can: be used to create multiple command buffers. If the creation of any of those command buffers fails, the implementation must: destroy all successfully created command buffer objects from this command, set all entries of the pname:pCommandBuffers array to `NULL` and return the error. endif::VK_KHR_maintenance1[] When command buffers are first allocated, they are in the <>. include::../validity/protos/vkAllocateCommandBuffers.txt[] -- [open,refpage='VkCommandBufferAllocateInfo',desc='Structure specifying the allocation parameters for command buffer object',type='structs'] -- The sname:VkCommandBufferAllocateInfo structure is defined as: include::../api/structs/VkCommandBufferAllocateInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:commandPool is the command pool from which the command buffers are allocated. * pname:level is an elink:VkCommandBufferLevel value specifying the command buffer level. * pname:commandBufferCount is the number of command buffers to allocate from the pool. .Valid Usage **** * [[VUID-VkCommandBufferAllocateInfo-commandBufferCount-00044]] pname:commandBufferCount must: be greater than `0` **** include::../validity/structs/VkCommandBufferAllocateInfo.txt[] -- [open,refpage='VkCommandBufferLevel',desc='Enumerant specifying a command buffer level',type='enums'] -- Possible values of slink:VkCommandBufferAllocateInfo::pname:flags, specifying the command buffer level, are: include::../api/enums/VkCommandBufferLevel.txt[] * ename:VK_COMMAND_BUFFER_LEVEL_PRIMARY specifies a primary command buffer. * ename:VK_COMMAND_BUFFER_LEVEL_SECONDARY specifies a secondary command buffer. -- [open,refpage='vkResetCommandBuffer',desc='Reset a command buffer to the initial state',type='protos'] -- To reset command buffers, call: include::../api/protos/vkResetCommandBuffer.txt[] * pname:commandBuffer is the command buffer to reset. The command buffer can: be in any state other than <>, and is moved into the <>. * pname:flags is a bitmask of elink:VkCommandBufferResetFlagBits controlling the reset operation. Any primary command buffer that is in the <> and has pname:commandBuffer recorded into it, becomes <>. .Valid Usage **** * [[VUID-vkResetCommandBuffer-commandBuffer-00045]] pname:commandBuffer must: not be in the <> * [[VUID-vkResetCommandBuffer-commandBuffer-00046]] pname:commandBuffer must: have been allocated from a pool that was created with the ename:VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT **** include::../validity/protos/vkResetCommandBuffer.txt[] -- [open,refpage='VkCommandBufferResetFlagBits',desc='Bitmask controlling behavior of a command buffer reset',type='enums'] -- Bits which can: be set in flink:vkResetCommandBuffer::pname:flags to control the reset operation are: include::../api/enums/VkCommandBufferResetFlagBits.txt[] * ename:VK_COMMAND_BUFFER_RESET_RELEASE_RESOURCES_BIT specifies that most or all memory resources currently owned by the command buffer should: be returned to the parent command pool. If this flag is not set, then the command buffer may: hold onto memory resources and reuse them when recording commands. pname:commandBuffer is moved to the <>. -- [open,refpage='vkFreeCommandBuffers',desc='Free command buffers',type='protos'] -- To free command buffers, call: include::../api/protos/vkFreeCommandBuffers.txt[] * pname:device is the logical device that owns the command pool. * pname:commandPool is the command pool from which the command buffers were allocated. * pname:commandBufferCount is the length of the pname:pCommandBuffers array. * pname:pCommandBuffers is an array of handles of command buffers to free. Any primary command buffer that is in the <> and has any element of pname:pCommandBuffers recorded into it, becomes <>. .Valid Usage **** * [[VUID-vkFreeCommandBuffers-pCommandBuffers-00047]] All elements of pname:pCommandBuffers must: not be in the <> * [[VUID-vkFreeCommandBuffers-pCommandBuffers-00048]] pname:pCommandBuffers must: be a pointer to an array of pname:commandBufferCount sname:VkCommandBuffer handles, each element of which must: either be a valid handle or `NULL` **** include::../validity/protos/vkFreeCommandBuffers.txt[] -- [[commandbuffers-recording]] == Command Buffer Recording [open,refpage='vkBeginCommandBuffer',desc='Start recording a command buffer',type='protos'] -- To begin recording a command buffer, call: include::../api/protos/vkBeginCommandBuffer.txt[] * pname:commandBuffer is the handle of the command buffer which is to be put in the recording state. * pname:pBeginInfo is an instance of the sname:VkCommandBufferBeginInfo structure, which defines additional information about how the command buffer begins recording. .Valid Usage **** * [[VUID-vkBeginCommandBuffer-commandBuffer-00049]] pname:commandBuffer must: not be in the <>. * [[VUID-vkBeginCommandBuffer-commandBuffer-00050]] If pname:commandBuffer was allocated from a slink:VkCommandPool which did not have the ename:VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT flag set, pname:commandBuffer must: be in the <>. * [[VUID-vkBeginCommandBuffer-commandBuffer-00051]] If pname:commandBuffer is a secondary command buffer, the pname:pInheritanceInfo member of pname:pBeginInfo must: be a valid sname:VkCommandBufferInheritanceInfo structure * [[VUID-vkBeginCommandBuffer-commandBuffer-00052]] If pname:commandBuffer is a secondary command buffer and either the pname:occlusionQueryEnable member of the pname:pInheritanceInfo member of pname:pBeginInfo is ename:VK_FALSE, or the precise occlusion queries feature is not enabled, the pname:queryFlags member of the pname:pInheritanceInfo member pname:pBeginInfo must: not contain ename:VK_QUERY_CONTROL_PRECISE_BIT **** include::../validity/protos/vkBeginCommandBuffer.txt[] -- [open,refpage='VkCommandBufferBeginInfo',desc='Structure specifying a command buffer begin operation',type='structs'] -- The sname:VkCommandBufferBeginInfo structure is defined as: include::../api/structs/VkCommandBufferBeginInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:flags is a bitmask of elink:VkCommandBufferUsageFlagBits specifying usage behavior for the command buffer. * pname:pInheritanceInfo is a pointer to a sname:VkCommandBufferInheritanceInfo structure, which is used if pname:commandBuffer is a secondary command buffer. If this is a primary command buffer, then this value is ignored. .Valid Usage **** * [[VUID-VkCommandBufferBeginInfo-flags-00053]] If pname:flags contains ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT, the pname:renderPass member of pname:pInheritanceInfo must: be a valid sname:VkRenderPass * [[VUID-VkCommandBufferBeginInfo-flags-00054]] If pname:flags contains ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT, the pname:subpass member of pname:pInheritanceInfo must: be a valid subpass index within the pname:renderPass member of pname:pInheritanceInfo * [[VUID-VkCommandBufferBeginInfo-flags-00055]] If pname:flags contains ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT, the pname:framebuffer member of pname:pInheritanceInfo must: be either dlink:VK_NULL_HANDLE, or a valid sname:VkFramebuffer that is compatible with the pname:renderPass member of pname:pInheritanceInfo **** include::../validity/structs/VkCommandBufferBeginInfo.txt[] -- [open,refpage='VkCommandBufferUsageFlagBits',desc='Bitmask specifying usage behavior for command buffer',type='enums'] -- Bits which can: be set in slink:VkCommandBufferBeginInfo::pname:flags to specify usage behavior for a command buffer are: include::../api/enums/VkCommandBufferUsageFlagBits.txt[] * ename:VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT specifies that each recording of the command buffer will only be submitted once, and the command buffer will be reset and recorded again between each submission. * ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT specifies that a secondary command buffer is considered to be entirely inside a render pass. If this is a primary command buffer, then this bit is ignored. * ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT specifies that a command buffer can: be resubmitted to a queue while it is in the _pending state_, and recorded into multiple primary command buffers. -- [open,refpage='VkCommandBufferInheritanceInfo',desc='Structure specifying command buffer inheritance info',type='structs'] -- If the command buffer is a secondary command buffer, then the sname:VkCommandBufferInheritanceInfo structure defines any state that will be inherited from the primary command buffer: include::../api/structs/VkCommandBufferInheritanceInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:renderPass is a sname:VkRenderPass object defining which render passes the sname:VkCommandBuffer will be <> with and can: be executed within. If the sname:VkCommandBuffer will not be executed within a render pass instance, pname:renderPass is ignored. * pname:subpass is the index of the subpass within the render pass instance that the sname:VkCommandBuffer will be executed within. If the sname:VkCommandBuffer will not be executed within a render pass instance, pname:subpass is ignored. * pname:framebuffer optionally refers to the sname:VkFramebuffer object that the sname:VkCommandBuffer will be rendering to if it is executed within a render pass instance. It can: be dlink:VK_NULL_HANDLE if the framebuffer is not known, or if the sname:VkCommandBuffer will not be executed within a render pass instance. + [NOTE] .Note ==== Specifying the exact framebuffer that the secondary command buffer will be executed with may: result in better performance at command buffer execution time. ==== * pname:occlusionQueryEnable indicates whether the command buffer can: be executed while an occlusion query is active in the primary command buffer. If this is ename:VK_TRUE, then this command buffer can: be executed whether the primary command buffer has an occlusion query active or not. If this is ename:VK_FALSE, then the primary command buffer must: not have an occlusion query active. * pname:queryFlags indicates the query flags that can: be used by an active occlusion query in the primary command buffer when this secondary command buffer is executed. If this value includes the ename:VK_QUERY_CONTROL_PRECISE_BIT bit, then the active query can: return boolean results or actual sample counts. If this bit is not set, then the active query must: not use the ename:VK_QUERY_CONTROL_PRECISE_BIT bit. * pname:pipelineStatistics is a bitmask of elink:VkQueryPipelineStatisticFlagBits specifying the set of pipeline statistics that can: be counted by an active query in the primary command buffer when this secondary command buffer is executed. If this value includes a given bit, then this command buffer can: be executed whether the primary command buffer has a pipeline statistics query active that includes this bit or not. If this value excludes a given bit, then the active pipeline statistics query must: not be from a query pool that counts that statistic. .Valid Usage **** * [[VUID-VkCommandBufferInheritanceInfo-occlusionQueryEnable-00056]] If the <> feature is not enabled, pname:occlusionQueryEnable must: be ename:VK_FALSE * [[VUID-VkCommandBufferInheritanceInfo-queryFlags-00057]] If the <> feature is enabled, pname:queryFlags must: be a valid combination of elink:VkQueryControlFlagBits values * [[VUID-VkCommandBufferInheritanceInfo-pipelineStatistics-00058]] If the <> feature is not enabled, pname:pipelineStatistics must: be code:0 **** include::../validity/structs/VkCommandBufferInheritanceInfo.txt[] -- If ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT was not set when creating a command buffer, that command buffer must: not be submitted to a queue whilst it is already in the <>. If ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT is not set on a secondary command buffer, that command buffer must: not be used more than once in a given primary command buffer. [NOTE] .Note ==== On some implementations, not using the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT bit enables command buffers to be patched in-place if needed, rather than creating a copy of the command buffer. ==== If a command buffer is in the <>, and the command buffer was allocated from a command pool with the ename:VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT flag set, then fname:vkBeginCommandBuffer implicitly resets the command buffer, behaving as if fname:vkResetCommandBuffer had been called with ename:VK_COMMAND_BUFFER_RESET_RELEASE_RESOURCES_BIT not set. After the implicit reset, pname:commandBuffer is moved to the <>. Once recording starts, an application records a sequence of commands (ftext:vkCmd*) to set state in the command buffer, draw, dispatch, and other commands. ifdef::VK_NVX_device_generated_commands[] Several commands can also be recorded indirectly from sname:VkBuffer content, see <>. endif::VK_NVX_device_generated_commands[] [open,refpage='vkEndCommandBuffer',desc='Finish recording a command buffer',type='protos'] -- To complete recording of a command buffer, call: include::../api/protos/vkEndCommandBuffer.txt[] * pname:commandBuffer is the command buffer to complete recording. If there was an error during recording, the application will be notified by an unsuccessful return code returned by fname:vkEndCommandBuffer. If the application wishes to further use the command buffer, the command buffer must: be reset. The command buffer must: have been in the <>, and is moved to the <>. .Valid Usage **** * [[VUID-vkEndCommandBuffer-commandBuffer-00059]] pname:commandBuffer must: be in the <>. * [[VUID-vkEndCommandBuffer-commandBuffer-00060]] If pname:commandBuffer is a primary command buffer, there must: not be an active render pass instance * [[VUID-vkEndCommandBuffer-commandBuffer-00061]] All queries made <> during the recording of pname:commandBuffer must: have been made inactive ifdef::VK_EXT_debug_marker[] * [[VUID-vkEndCommandBuffer-commandBuffer-00062]] If pname:commandBuffer is a secondary command buffer, there must: not be an outstanding flink:vkCmdDebugMarkerBeginEXT command recorded to pname:commandBuffer that has not previously been ended by a call to flink:vkCmdDebugMarkerEndEXT. endif::VK_EXT_debug_marker[] **** include::../validity/protos/vkEndCommandBuffer.txt[] -- When a command buffer is in the executable state, it can: be submitted to a queue for execution. [[commandbuffers-submission]] == Command Buffer Submission [open,refpage='vkQueueSubmit',desc='Submits a sequence of semaphores or command buffers to a queue',type='protos'] -- To submit command buffers to a queue, call: include::../api/protos/vkQueueSubmit.txt[] * pname:queue is the queue that the command buffers will be submitted to. * pname:submitCount is the number of elements in the pname:pSubmits array. * pname:pSubmits is a pointer to an array of slink:VkSubmitInfo structures, each specifying a command buffer submission batch. * pname:fence is an optional: handle to a fence to be signaled once all submitted command buffers have completed execution. If pname:fence is not dlink:VK_NULL_HANDLE, it defines a <>. [NOTE] .Note ==== Submission can be a high overhead operation, and applications should: attempt to batch work together into as few calls to fname:vkQueueSubmit as possible. ==== fname:vkQueueSubmit is a <>, with each batch defined by an element of pname:pSubmits as an instance of the slink:VkSubmitInfo structure. Batches begin execution in the order they appear in pname:pSubmits, but may: complete out of order. Fence and semaphore operations submitted with flink:vkQueueSubmit have additional ordering constraints compared to other submission commands, with dependencies involving previous and subsequent queue operations. Information about these additional constraints can be found in the <> and <> sections of <>. Details on the interaction of pname:pWaitDstStageMask with synchronization are described in the <> section of <>. The order that batches appear in pname:pSubmits is used to determine <>, and thus all the <> that respect it. Other than these implicit ordering guarantees and any <>, these batches may: overlap or otherwise execute out of order. If any command buffer submitted to this queue is in the <>, it is moved to the <>. Once execution of all submissions of a command buffer complete, it moves from the <>, back to the <>. If a command buffer was recorded with the ename:VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT flag, it instead moves back to the <>. If fname:vkQueueSubmit fails, it may: return ename:VK_ERROR_OUT_OF_HOST_MEMORY or ename:VK_ERROR_OUT_OF_DEVICE_MEMORY. If it does, the implementation must: ensure that the state and contents of any resources or synchronization primitives referenced by the submitted command buffers and any semaphores referenced by pname:pSubmits is unaffected by the call or its failure. If fname:vkQueueSubmit fails in such a way that the implementation can: not make that guarantee, the implementation must: return ename:VK_ERROR_DEVICE_LOST. See <>. .Valid Usage **** * [[VUID-vkQueueSubmit-fence-00063]] If pname:fence is not dlink:VK_NULL_HANDLE, pname:fence must: be unsignaled * [[VUID-vkQueueSubmit-fence-00064]] If pname:fence is not dlink:VK_NULL_HANDLE, pname:fence must: not be associated with any other queue command that has not yet completed execution on that queue * [[VUID-vkQueueSubmit-pCommandBuffers-00065]] Any calls to flink:vkCmdSetEvent, flink:vkCmdResetEvent or flink:vkCmdWaitEvents that have been recorded into any of the command buffer elements of the pname:pCommandBuffers member of any element of pname:pSubmits, must: not reference any slink:VkEvent that is referenced by any of those commands in a command buffer that has been submitted to another queue and is still in the _pending state_. * [[VUID-vkQueueSubmit-pWaitDstStageMask-00066]] Any stage flag included in any element of the pname:pWaitDstStageMask member of any element of pname:pSubmits must: be a pipeline stage supported by one of the capabilities of pname:queue, as specified in the <>. * [[VUID-vkQueueSubmit-pSignalSemaphores-00067]] Each element of the pname:pSignalSemaphores member of any element of pname:pSubmits must: be unsignaled when the semaphore signal operation it defines is executed on the device * [[VUID-vkQueueSubmit-pWaitSemaphores-00068]] When a semaphore unsignal operation defined by any element of the pname:pWaitSemaphores member of any element of pname:pSubmits executes on pname:queue, no other queue must: be waiting on the same semaphore. * [[VUID-vkQueueSubmit-pWaitSemaphores-00069]] All elements of the pname:pWaitSemaphores member of all elements of pname:pSubmits must: be semaphores that are signaled, or have <> previously submitted for execution. * [[VUID-vkQueueSubmit-pCommandBuffers-00070]] Each element of the pname:pCommandBuffers member of each element of pname:pSubmits must: be in the <>. * [[VUID-vkQueueSubmit-pCommandBuffers-00071]] If any element of the pname:pCommandBuffers member of any element of pname:pSubmits was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT, it must: not be in the <>. * [[VUID-vkQueueSubmit-pCommandBuffers-00072]] Any <> into any element of the pname:pCommandBuffers member of any element of pname:pSubmits must: be in the <>. * [[VUID-vkQueueSubmit-pCommandBuffers-00073]] If any <> into any element of the pname:pCommandBuffers member of any element of pname:pSubmits was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT, it must: not be in the <>. * [[VUID-vkQueueSubmit-pCommandBuffers-00074]] Each element of the pname:pCommandBuffers member of each element of pname:pSubmits must: have been allocated from a sname:VkCommandPool that was created for the same queue family pname:queue belongs to. **** include::../validity/protos/vkQueueSubmit.txt[] -- [open,refpage='VkSubmitInfo',desc='Structure specifying a queue submit operation',type='structs'] -- The sname:VkSubmitInfo structure is defined as: include::../api/structs/VkSubmitInfo.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:waitSemaphoreCount is the number of semaphores upon which to wait before executing the command buffers for the batch. * pname:pWaitSemaphores is a pointer to an array of semaphores upon which to wait before the command buffers for this batch begin execution. If semaphores to wait on are provided, they define a <>. * pname:pWaitDstStageMask is a pointer to an array of pipeline stages at which each corresponding semaphore wait will occur. * pname:commandBufferCount is the number of command buffers to execute in the batch. * pname:pCommandBuffers is a pointer to an array of command buffers to execute in the batch. * pname:signalSemaphoreCount is the number of semaphores to be signaled once the commands specified in pname:pCommandBuffers have completed execution. * pname:pSignalSemaphores is a pointer to an array of semaphores which will be signaled when the command buffers for this batch have completed execution. If semaphores to be signaled are provided, they define a <>. The order that command buffers appear in pname:pCommandBuffers is used to determine <>, and thus all the <> that respect it. Other than these implicit ordering guarantees and any <>, these command buffers may: overlap or otherwise execute out of order. .Valid Usage **** * [[VUID-VkSubmitInfo-pCommandBuffers-00075]] Each element of pname:pCommandBuffers must: not have been allocated with ename:VK_COMMAND_BUFFER_LEVEL_SECONDARY * [[VUID-VkSubmitInfo-pWaitDstStageMask-00076]] If the <> feature is not enabled, each element of pname:pWaitDstStageMask must: not contain ename:VK_PIPELINE_STAGE_GEOMETRY_SHADER_BIT * [[VUID-VkSubmitInfo-pWaitDstStageMask-00077]] If the <> feature is not enabled, each element of pname:pWaitDstStageMask must: not contain ename:VK_PIPELINE_STAGE_TESSELLATION_CONTROL_SHADER_BIT or ename:VK_PIPELINE_STAGE_TESSELLATION_EVALUATION_SHADER_BIT * [[VUID-VkSubmitInfo-pWaitDstStageMask-00078]] Each element of pname:pWaitDstStageMask must: not include ename:VK_PIPELINE_STAGE_HOST_BIT. **** include::../validity/structs/VkSubmitInfo.txt[] -- ifdef::VK_KHR_external_semaphore_win32[] [open,refpage='VkD3D12FenceSubmitInfoKHR',desc='Structure specifying values for Direct3D 12 fence-backed semaphores',type='structs'] -- To specify the values to use when waiting for and signaling semaphores whose <> refers to a Direct3D 12 fence, add the slink:VkD3D12FenceSubmitInfoKHR structure to the pname:pNext chain of the slink:VkSubmitInfo structure. The sname:VkD3D12FenceSubmitInfoKHR structure is defined as: include::../api/structs/VkD3D12FenceSubmitInfoKHR.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:waitSemaphoreValuesCount is the number of semaphore wait values specified in pname:pWaitSemaphoreValues. * pname:pWaitSemaphoreValues is an array of length pname:waitSemaphoreValuesCount containing values for the corresponding semaphores in slink:VkSubmitInfo::pname:pWaitSemaphores to wait for. * pname:signalSemaphoreValuesCount is the number of semaphore signal values specified in pname:pSignalSemaphoreValues. * pname:pSignalSemaphoreValues is an array of length pname:signalSemaphoreValuesCount containing values for the corresponding semaphores in slink:VkSubmitInfo::pname:pSignalSemaphores to set when signaled. If the semaphore in slink:VkSubmitInfo::pname:pWaitSemaphores or slink:VkSubmitInfo::pname:pSignalSemaphores corresponding to an entry in pname:pWaitSemaphoreValues or pname:pSignalSemaphoreValues respectively does not currently have a <> referring to a Direct3D 12 fence, the implementation must: ignore the value in the pname:pWaitSemaphoreValues or pname:pSignalSemaphoreValues entry. .Valid Usage **** * [[VUID-VkD3D12FenceSubmitInfoKHR-waitSemaphoreValuesCount-00079]] pname:waitSemaphoreValuesCount must: be the same value as sname:VkSubmitInfo::pname:waitSemaphoreCount, where sname:VkSubmitInfo is in the pname:pNext chain of this sname:VkD3D12FenceSubmitInfoKHR structure. * [[VUID-VkD3D12FenceSubmitInfoKHR-signalSemaphoreValuesCount-00080]] pname:signalSemaphoreValuesCount must: be the same value as sname:VkSubmitInfo::pname:signalSemaphoreCount, where sname:VkSubmitInfo is in the pname:pNext chain of this sname:VkD3D12FenceSubmitInfoKHR structure. **** include::../validity/structs/VkD3D12FenceSubmitInfoKHR.txt[] -- endif::VK_KHR_external_semaphore_win32[] ifdef::VK_KHR_win32_keyed_mutex[] [open,refpage='VkWin32KeyedMutexAcquireReleaseInfoKHR',desc='Use the Windows keyed mutex mechanism to synchronize work',type='structs'] -- When submitting work that operates on memory imported from a Direct3D 11 resource to a queue, the keyed mutex mechanism may: be used in addition to Vulkan semaphores to synchronize the work. Keyed mutexes are a property of a properly created shareable Direct3D 11 resource. They can: only be used if the imported resource was created with the etext:D3D11_RESOURCE_MISC_SHARED_KEYEDMUTEX flag. To acquire keyed mutexes before submitted work and/or release them after, add a slink:VkWin32KeyedMutexAcquireReleaseInfoKHR structure to the pname:pNext chain of the slink:VkSubmitInfo structure. The sname:VkWin32KeyedMutexAcquireReleaseInfoKHR structure is defined as: include::../api/structs/VkWin32KeyedMutexAcquireReleaseInfoKHR.txt[] * pname:acquireCount is the number of entries in the pname:pAcquireSyncs, pname:pAcquireKeys, and pname:pAcquireTimeoutMilliseconds arrays. * pname:pAcquireSyncs is a pointer to an array of slink:VkDeviceMemory objects which were imported from Direct3D 11 resources. * pname:pAcquireKeys is a pointer to an array of mutex key values to wait for prior to beginning the submitted work. Entries refer to the keyed mutex associated with the corresponding entries in pname:pAcquireSyncs. * pname:pAcquireTimeoutMilliseconds is an array of timeout values, in millisecond units, for each acquire specified in pname:pAcquireKeys. * pname:releaseCount is the number of entries in the pname:pReleaseSyncs and pname:pReleaseKeys arrays. * pname:pReleaseSyncs is a pointer to an array of slink:VkDeviceMemory objects which were imported from Direct3D 11 resources. * pname:pReleaseKeys is a pointer to an array of mutex key values to set when the submitted work has completed. Entries refer to the keyed mutex associated with the corresponding entries in pname:pReleaseSyncs. .Valid Usage **** * [[VUID-VkWin32KeyedMutexAcquireReleaseInfoKHR-pAcquireSyncs-00081]] Each member of pname:pAcquireSyncs and pname:pReleaseSyncs must: be a device memory object imported by setting slink:VkImportMemoryWin32HandleInfoKHR::pname:handleType to ename:VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_BIT_KHR or ename:VK_EXTERNAL_MEMORY_HANDLE_TYPE_D3D11_TEXTURE_KMT_BIT_KHR. **** include::../validity/structs/VkWin32KeyedMutexAcquireReleaseInfoKHR.txt[] -- endif::VK_KHR_win32_keyed_mutex[] ifdef::VK_NV_win32_keyed_mutex[] include::VK_NV_win32_keyed_mutex/keyed_mutex_submit.txt[] endif::VK_NV_win32_keyed_mutex[] ifdef::VK_KHX_device_group[] [open,refpage='VkDeviceGroupSubmitInfoKHX',desc='Structure indicating which physical devices execute semaphore operations and command buffers',type='structs'] -- If the pname:pNext chain of slink:VkSubmitInfo includes a sname:VkDeviceGroupSubmitInfoKHX structure, then that structure includes device indices and masks specifying which physical devices execute semaphore operations and command buffers. The sname:VkDeviceGroupSubmitInfoKHX structure is defined as: include::../api/structs/VkDeviceGroupSubmitInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:waitSemaphoreCount is the number of elements in the pname:pWaitSemaphoreDeviceIndices array. * pname:pWaitSemaphoreDeviceIndices is an array of device indices indicating which physical device executes the semaphore wait operation in the corresponding element of slink:VkSubmitInfo::pname:pWaitSemaphores. * pname:commandBufferCount is the number of elements in the pname:pCommandBufferDeviceMasks array. * pname:pCommandBufferDeviceMasks is an array of device masks indicating which physical devices execute the command buffer in the corresponding element of slink:VkSubmitInfo::pname:pCommandBuffers. A physical device executes the command buffer if the corresponding bit is set in the mask. * pname:signalSemaphoreCount is the number of elements in the pname:pSignalSemaphoreDeviceIndices array. * pname:pSignalSemaphoreDeviceIndices is an array of device indices indicating which physical device executes the semaphore signal operation in the corresponding element of slink:VkSubmitInfo::pname:pSignalSemaphores. If this structure is not present, semaphore operations and command buffers execute on device index zero. .Valid Usage **** * [[VUID-VkDeviceGroupSubmitInfoKHX-waitSemaphoreCount-00082]] pname:waitSemaphoreCount must: equal slink:VkSubmitInfo::pname:waitSemaphoreCount * [[VUID-VkDeviceGroupSubmitInfoKHX-commandBufferCount-00083]] pname:commandBufferCount must: equal slink:VkSubmitInfo::pname:commandBufferCount * [[VUID-VkDeviceGroupSubmitInfoKHX-signalSemaphoreCount-00084]] pname:signalSemaphoreCount must: equal slink:VkSubmitInfo::pname:signalSemaphoreCount * [[VUID-VkDeviceGroupSubmitInfoKHX-pWaitSemaphoreDeviceIndices-00085]] All elements of pname:pWaitSemaphoreDeviceIndices and pname:pSignalSemaphoreDeviceIndices must: be valid device indices * [[VUID-VkDeviceGroupSubmitInfoKHX-pCommandBufferDeviceMasks-00086]] All elements of pname:pCommandBufferDeviceMasks must: be valid device masks **** include::../validity/structs/VkDeviceGroupSubmitInfoKHX.txt[] -- endif::VK_KHX_device_group[] [[commandbuffers-submission-progress]] == Queue Forward Progress The application must: ensure that command buffer submissions will be able to complete without any subsequent operations by the application on any queue. After any call to fname:vkQueueSubmit, for every queued wait on a semaphore there must: be a prior signal of that semaphore that will not be consumed by a different wait on the semaphore. Command buffers in the submission can: include flink:vkCmdWaitEvents commands that wait on events that will not be signaled by earlier commands in the queue. Such events must: be signaled by the application using flink:vkSetEvent, and the fname:vkCmdWaitEvents commands that wait upon them must: not be inside a render pass instance. Implementations may: have limits on how long the command buffer will wait, in order to avoid interfering with progress of other clients of the device. If the event is not signaled within these limits, results are undefined and may: include device loss. [[commandbuffers-secondary]] == Secondary Command Buffer Execution [open,refpage='vkCmdExecuteCommands',desc='Execute a secondary command buffer from a primary command buffer',type='protos'] -- A secondary command buffer must: not be directly submitted to a queue. Instead, secondary command buffers are recorded to execute as part of a primary command buffer with the command: include::../api/protos/vkCmdExecuteCommands.txt[] * pname:commandBuffer is a handle to a primary command buffer that the secondary command buffers are executed in. * pname:commandBufferCount is the length of the pname:pCommandBuffers array. * pname:pCommandBuffers is an array of secondary command buffer handles, which are recorded to execute in the primary command buffer in the order they are listed in the array. If any element of pname:pCommandBuffers was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT flag, and it was recorded into any other primary command buffer which is currently in the <>, that primary command buffer becomes <>. .Valid Usage **** * [[VUID-vkCmdExecuteCommands-commandBuffer-00087]] pname:commandBuffer must: have been allocated with a pname:level of ename:VK_COMMAND_BUFFER_LEVEL_PRIMARY * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00088]] Each element of pname:pCommandBuffers must: have been allocated with a pname:level of ename:VK_COMMAND_BUFFER_LEVEL_SECONDARY * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00089]] Each element of pname:pCommandBuffers must: be in the <>. * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00090]] If any element of pname:pCommandBuffers was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT flag, and it was recorded into any other primary command buffer, that primary command buffer must: not be in the <> * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00091]] If any element of pname:pCommandBuffers was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT flag, it must: not be in the <>. * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00092]] If any element of pname:pCommandBuffers was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT flag, it must: not have already been recorded to pname:commandBuffer. * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00093]] If any element of pname:pCommandBuffers was not recorded with the ename:VK_COMMAND_BUFFER_USAGE_SIMULTANEOUS_USE_BIT flag, it must: not appear more than once in pname:pCommandBuffers. * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00094]] Each element of pname:pCommandBuffers must: have been allocated from a sname:VkCommandPool that was created for the same queue family as the sname:VkCommandPool from which pname:commandBuffer was allocated * [[VUID-vkCmdExecuteCommands-contents-00095]] If fname:vkCmdExecuteCommands is being called within a render pass instance, that render pass instance must: have been begun with the pname:contents parameter of fname:vkCmdBeginRenderPass set to ename:VK_SUBPASS_CONTENTS_SECONDARY_COMMAND_BUFFERS * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00096]] If fname:vkCmdExecuteCommands is being called within a render pass instance, each element of pname:pCommandBuffers must: have been recorded with the ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00097]] If fname:vkCmdExecuteCommands is being called within a render pass instance, each element of pname:pCommandBuffers must: have been recorded with sname:VkCommandBufferInheritanceInfo::pname:subpass set to the index of the subpass which the given command buffer will be executed in * [[VUID-vkCmdExecuteCommands-pInheritanceInfo-00098]] If fname:vkCmdExecuteCommands is being called within a render pass instance, the render passes specified in the pname::pBeginInfo::pname:pInheritanceInfo::pname:renderPass members of the flink:vkBeginCommandBuffer commands used to begin recording each element of pname:pCommandBuffers must: be <> with the current render pass. * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00099]] If fname:vkCmdExecuteCommands is being called within a render pass instance, and any element of pname:pCommandBuffers was recorded with sname:VkCommandBufferInheritanceInfo::pname:framebuffer not equal to dlink:VK_NULL_HANDLE, that sname:VkFramebuffer must: match the sname:VkFramebuffer used in the current render pass instance * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00100]] If fname:vkCmdExecuteCommands is not being called within a render pass instance, each element of pname:pCommandBuffers must: not have been recorded with the ename:VK_COMMAND_BUFFER_USAGE_RENDER_PASS_CONTINUE_BIT * [[VUID-vkCmdExecuteCommands-commandBuffer-00101]] If the <> feature is not enabled, pname:commandBuffer must: not have any queries <> * [[VUID-vkCmdExecuteCommands-commandBuffer-00102]] If pname:commandBuffer has a ename:VK_QUERY_TYPE_OCCLUSION query <>, then each element of pname:pCommandBuffers must: have been recorded with sname:VkCommandBufferInheritanceInfo::pname:occlusionQueryEnable set to ename:VK_TRUE * [[VUID-vkCmdExecuteCommands-commandBuffer-00103]] If pname:commandBuffer has a ename:VK_QUERY_TYPE_OCCLUSION query <>, then each element of pname:pCommandBuffers must: have been recorded with sname:VkCommandBufferInheritanceInfo::pname:queryFlags having all bits set that are set for the query * [[VUID-vkCmdExecuteCommands-commandBuffer-00104]] If pname:commandBuffer has a ename:VK_QUERY_TYPE_PIPELINE_STATISTICS query <>, then each element of pname:pCommandBuffers must: have been recorded with sname:VkCommandBufferInheritanceInfo::pname:pipelineStatistics having all bits set that are set in the sname:VkQueryPool the query uses * [[VUID-vkCmdExecuteCommands-pCommandBuffers-00105]] Each element of pname:pCommandBuffers must: not begin any query types that are <> in pname:commandBuffer **** include::../validity/protos/vkCmdExecuteCommands.txt[] -- ifdef::VK_KHX_device_group[] [[commandbuffers-devicemask]] == Command Buffer Device Mask Each command buffer has a piece of state storing the current device mask of the command buffer. This mask controls which physical devices within the logical device all subsequent commands will execute on, including state-setting commands, action commands, and synchronization commands. Scissor and viewport state can: be set to different values on each physical device (only when set as dynamic state), and each physical device will render using its local copy of the state. Other state is shared between physical devices, such that all physical devices use the most recently set values for the state. However, when recording an action command that uses a piece of state, the most recent command that set that state must: have included all physical devices that execute the action command in its current device mask. The command buffer's device mask is orthogonal to the pname:pCommandBufferDeviceMasks member of slink:VkDeviceGroupSubmitInfoKHX. Commands only execute on a physical device if the device index is set in both device masks. [open,refpage='VkDeviceGroupCommandBufferBeginInfoKHX',desc='Set the initial device mask for a command buffer',type='structs'] -- If the pname:pNext chain of slink:VkCommandBufferBeginInfo includes a sname:VkDeviceGroupCommandBufferBeginInfoKHX structure, then that structure includes an initial device mask for the command buffer. The sname:VkDeviceGroupCommandBufferBeginInfoKHX structure is defined as: include::../api/structs/VkDeviceGroupCommandBufferBeginInfoKHX.txt[] * pname:sType is the type of this structure. * pname:pNext is `NULL` or a pointer to an extension-specific structure. * pname:deviceMask is the initial value of the command buffer's device mask. The initial device mask also acts as an upper bound on the set of devices that can: ever be in the device mask in the command buffer. If this structure is not present, the initial value of a command buffer's device mask is set to include all physical devices in the logical device when the command buffer begins recording. .Valid Usage **** * [[VUID-VkDeviceGroupCommandBufferBeginInfoKHX-deviceMask-00106]] pname:deviceMask must: be a valid device mask value * [[VUID-VkDeviceGroupCommandBufferBeginInfoKHX-deviceMask-00107]] pname:deviceMask must: not be zero **** include::../validity/structs/VkDeviceGroupCommandBufferBeginInfoKHX.txt[] -- [open,refpage='vkCmdSetDeviceMaskKHX',desc='Modify device mask of a command buffer',type='protos'] -- To update the current device mask of a command buffer, call: include::../api/protos/vkCmdSetDeviceMaskKHX.txt[] * pname:commandBuffer is command buffer whose current device mask is modified. * pname:deviceMask is the new value of the current device mask. pname:deviceMask is used to filter out subsequent commands from executing on all physical devices whose bit indices are not set in the mask. .Valid Usage **** * [[VUID-vkCmdSetDeviceMaskKHX-deviceMask-00108]] pname:deviceMask must: be a valid device mask value * [[VUID-vkCmdSetDeviceMaskKHX-deviceMask-00109]] pname:deviceMask must: not be zero * [[VUID-vkCmdSetDeviceMaskKHX-deviceMask-00110]] pname:deviceMask must: not include any set bits that were not in the slink:VkDeviceGroupCommandBufferBeginInfoKHX::pname:deviceMask value when the command buffer began recording. * [[VUID-vkCmdSetDeviceMaskKHX-deviceMask-00111]] If fname:vkCmdSetDeviceMaskKHX is called inside a render pass instance, pname:deviceMask must: not include any set bits that were not in the slink:VkDeviceGroupRenderPassBeginInfoKHX::pname:deviceMask value when the render pass instance began recording. **** include::../validity/protos/vkCmdSetDeviceMaskKHX.txt[] -- endif::VK_KHX_device_group[]