vkGetFenceFdKHR - Get a POSIX file descriptor handle for a fence

Description

Each call to getFenceFdKHR must create a new file descriptor and transfer ownership of it to the application. To avoid leaking resources, the application must release ownership of the file descriptor when it is no longer needed.

Note

Ownership can be released in many ways. For example, the application can call close() on the file descriptor, or transfer ownership back to Vulkan by using the file descriptor to import a fence payload.

If pGetFdInfo->handleType is EXTERNAL_FENCE_HANDLE_TYPE_SYNC_FD_BIT and the fence is signaled at the time getFenceFdKHR is called, pFd may return the value -1 instead of a valid file descriptor.

Where supported by the operating system, the implementation must set the file descriptor to be closed automatically when an execve system call is made.

Exporting a file descriptor from a fence may have side effects depending on the transference of the specified handle type, as described in Importing Fence State.

Return Codes

Success

• SUCCESS

Failure

• ERROR_TOO_MANY_OBJECTS
• ERROR_OUT_OF_HOST_MEMORY

See Also

VK_KHR_external_fence_fd, Device, FenceGetFdInfoKHR

vkImportFenceFdKHR - Import a fence from a POSIX file descriptor

Description

Importing a fence payload from a file descriptor transfers ownership of the file descriptor from the application to the Vulkan implementation. The application must not perform any operations on the file descriptor after a successful import.

Applications can import the same fence payload into multiple instances of Vulkan, into the same instance from which it was exported, and multiple times into a given Vulkan instance.

Return Codes

Success

• SUCCESS

Failure

• ERROR_OUT_OF_HOST_MEMORY
• ERROR_INVALID_EXTERNAL_HANDLE

See Also

VK_KHR_external_fence_fd, Device, ImportFenceFdInfoKHR

VkImportFenceFdInfoKHR - (None)

Description

The handle types supported by handleType are:

Handle Types Supported by ImportFenceFdInfoKHR

Valid Usage

• handleType must be a value included in the Handle Types Supported by table

• fd must obey any requirements listed for handleType in external fence handle types compatibility
• If handleType refers to a handle type with copy payload transference semantics, flags must contain FENCE_IMPORT_TEMPORARY_BIT

If handleType is EXTERNAL_FENCE_HANDLE_TYPE_SYNC_FD_BIT, the special value -1 for fd is treated like a valid sync file descriptor referring to an object that has already signaled. The import operation will succeed and the Fence will have a temporarily imported payload as if a valid file descriptor had been provided.

Note

This special behavior for importing an invalid sync file descriptor allows easier interoperability with other system APIs which use the convention that an invalid sync file descriptor represents work that has already completed and does not need to be waited for. It is consistent with the option for implementations to return a -1 file descriptor when exporting a EXTERNAL_FENCE_HANDLE_TYPE_SYNC_FD_BIT from a Fence which is signaled.

Valid Usage (Implicit)

• sType must be STRUCTURE_TYPE_IMPORT_FENCE_FD_INFO_KHR

• pNext must be NULL
• fence must be a valid Fence handle
• flags must be a valid combination of FenceImportFlagBits values
• handleType must be a valid ExternalFenceHandleTypeFlagBits value

Host Synchronization

• Host access to fence must be externally synchronized

See Also

VK_KHR_external_fence_fd, ExternalFenceHandleTypeFlagBits, Fence, FenceImportFlags, StructureType, importFenceFdKHR

VkFenceGetFdInfoKHR - Structure describing a POSIX FD fence export operation

Description

The properties of the file descriptor returned depend on the value of handleType. See ExternalFenceHandleTypeFlagBits for a description of the properties of the defined external fence handle types.

Valid Usage

• handleType must have been included in ExportFenceCreateInfo::handleTypes when fence’s current payload was created

• If handleType refers to a handle type with copy payload transference semantics, fence must be signaled, or have an associated fence signal operation pending execution
• fence must not currently have its payload replaced by an imported payload as described below in Importing Fence Payloads unless that imported payload’s handle type was included in ExternalFenceProperties::exportFromImportedHandleTypes for handleType
• handleType must be defined as a POSIX file descriptor handle

Valid Usage (Implicit)

• sType must be STRUCTURE_TYPE_FENCE_GET_FD_INFO_KHR

• pNext must be NULL
• fence must be a valid Fence handle
• handleType must be a valid ExternalFenceHandleTypeFlagBits value

See Also

VK_KHR_external_fence_fd, ExternalFenceHandleTypeFlagBits, Fence, StructureType, getFenceFdKHR