C Specification

To import a semaphore payload from a POSIX file descriptor, call:

// Provided by VK_KHR_external_semaphore_fd
VkResult vkImportSemaphoreFdKHR(
    VkDevice                                    device,
    const VkImportSemaphoreFdInfoKHR*           pImportSemaphoreFdInfo);


  • device is the logical device that created the semaphore.

  • pImportSemaphoreFdInfo is a pointer to a VkImportSemaphoreFdInfoKHR structure specifying the semaphore and import parameters.


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.

If VkPhysicalDeviceVulkanSC10Properties::deviceNoDynamicHostAllocations is VK_TRUE, vkImportSemaphoreFdKHR must not return VK_ERROR_OUT_OF_HOST_MEMORY.

Valid Usage
  • VUID-vkImportSemaphoreFdKHR-semaphore-01142
    semaphore must not be associated with any queue command that has not yet completed execution on that queue

Valid Usage (Implicit)
  • VUID-vkImportSemaphoreFdKHR-device-parameter
    device must be a valid VkDevice handle

  • VUID-vkImportSemaphoreFdKHR-pImportSemaphoreFdInfo-parameter
    pImportSemaphoreFdInfo must be a valid pointer to a valid VkImportSemaphoreFdInfoKHR structure

Return Codes
On success, this command returns

On failure, this command returns


See Also

Document Notes

For more information, see the Vulkan Specification

This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.

Copyright 2014-2023 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0