vkGetSemaphoreFdKHR - Get a POSIX file descriptor handle for a semaphore

Description

Each call to getSemaphoreFdKHR 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 semaphore payload.

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 semaphore may have side effects depending on the transference of the specified handle type, as described in Importing Semaphore State.

Return Codes

Success

• SUCCESS

Failure

• ERROR_TOO_MANY_OBJECTS
• ERROR_OUT_OF_HOST_MEMORY

See Also

VK_KHR_external_semaphore_fd, Device, SemaphoreGetFdInfoKHR

vkImportSemaphoreFdKHR - Import a semaphore from a POSIX file descriptor

Description

Importing a semaphore 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 semaphore 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_semaphore_fd, Device, ImportSemaphoreFdInfoKHR

VkImportSemaphoreFdInfoKHR - Structure specifying POSIX file descriptor to import to a semaphore

Description

The handle types supported by handleType are:

Handle Types Supported by ImportSemaphoreFdInfoKHR

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 semaphore handle types compatibility
• If handleType is EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT, the SemaphoreCreateInfo::flags field must match that of the semaphore from which fd was exported
• If handleType refers to a handle type with copy payload transference semantics, flags must contain SEMAPHORE_IMPORT_TEMPORARY_BIT
• If handleType is EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT, the SemaphoreTypeCreateInfo::semaphoreType field must match that of the semaphore from which fd was exported
• If flags contains SEMAPHORE_IMPORT_TEMPORARY_BIT, the SemaphoreTypeCreateInfo::semaphoreType field of the semaphore from which fd was exported must not be SEMAPHORE_TYPE_TIMELINE

If handleType is EXTERNAL_SEMAPHORE_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 Semaphore 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_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT from a Semaphore which is signaled.

Valid Usage (Implicit)

• sType must be STRUCTURE_TYPE_IMPORT_SEMAPHORE_FD_INFO_KHR

• pNext must be NULL
• semaphore must be a valid Semaphore handle
• flags must be a valid combination of SemaphoreImportFlagBits values
• handleType must be a valid ExternalSemaphoreHandleTypeFlagBits value

Host Synchronization

• Host access to semaphore must be externally synchronized

See Also

VK_KHR_external_semaphore_fd, ExternalSemaphoreHandleTypeFlagBits, Semaphore, SemaphoreImportFlags, StructureType, importSemaphoreFdKHR

VkSemaphoreGetFdInfoKHR - Structure describing a POSIX FD semaphore export operation

Description

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

Valid Usage

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

• semaphore must not currently have its payload replaced by an imported payload as described below in Importing Semaphore Payloads unless that imported payload’s handle type was included in ExternalSemaphoreProperties::exportFromImportedHandleTypes for handleType
• If handleType refers to a handle type with copy payload transference semantics, as defined below in Importing Semaphore Payloads, there must be no queue waiting on semaphore
• If handleType refers to a handle type with copy payload transference semantics, semaphore must be signaled, or have an associated semaphore signal operation pending execution
• handleType must be defined as a POSIX file descriptor handle
• If handleType refers to a handle type with copy payload transference semantics, semaphore must have been created with a SemaphoreType of SEMAPHORE_TYPE_BINARY
• If handleType refers to a handle type with copy payload transference semantics, semaphore must have an associated semaphore signal operation that has been submitted for execution and any semaphore signal operations on which it depends (if any) must have also been submitted for execution

Valid Usage (Implicit)

• sType must be STRUCTURE_TYPE_SEMAPHORE_GET_FD_INFO_KHR

• pNext must be NULL
• semaphore must be a valid Semaphore handle
• handleType must be a valid ExternalSemaphoreHandleTypeFlagBits value

See Also

VK_KHR_external_semaphore_fd, ExternalSemaphoreHandleTypeFlagBits, Semaphore, StructureType, getSemaphoreFdKHR