C Specification

The VkImportFenceFdInfoKHR structure is defined as:

// Provided by VK_KHR_external_fence_fd
typedef struct VkImportFenceFdInfoKHR {
    VkStructureType                      sType;
    const void*                          pNext;
    VkFence                              fence;
    VkFenceImportFlags                   flags;
    VkExternalFenceHandleTypeFlagBits    handleType;
    int                                  fd;
} VkImportFenceFdInfoKHR;


  • sType is a VkStructureType value identifying this structure.

  • pNext is NULL or a pointer to a structure extending this structure.

  • fence is the fence into which the payload will be imported.

  • flags is a bitmask of VkFenceImportFlagBits specifying additional parameters for the fence payload import operation.

  • handleType is a VkExternalFenceHandleTypeFlagBits value specifying the type of fd.

  • fd is the external handle to import.


The handle types supported by handleType are:

Table 1. Handle Types Supported by VkImportFenceFdInfoKHR
Handle Type Transference Permanence Supported







Valid Usage
  • VUID-VkImportFenceFdInfoKHR-handleType-01464
    handleType must be a value included in the Handle Types Supported by VkImportFenceFdInfoKHR table

  • VUID-VkImportFenceFdInfoKHR-fd-01541
    fd must obey any requirements listed for handleType in external fence handle types compatibility

  • VUID-VkImportFenceFdInfoKHR-handleType-07306
    If handleType refers to a handle type with copy payload transference semantics, flags must contain VK_FENCE_IMPORT_TEMPORARY_BIT

If handleType is VK_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 VkFence will have a temporarily imported payload as if a valid file descriptor had been provided.


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 VK_EXTERNAL_FENCE_HANDLE_TYPE_SYNC_FD_BIT from a VkFence which is signaled.

Valid Usage (Implicit)
  • VUID-VkImportFenceFdInfoKHR-sType-sType

  • VUID-VkImportFenceFdInfoKHR-pNext-pNext
    pNext must be NULL

  • VUID-VkImportFenceFdInfoKHR-fence-parameter
    fence must be a valid VkFence handle

  • VUID-VkImportFenceFdInfoKHR-flags-parameter
    flags must be a valid combination of VkFenceImportFlagBits values

  • VUID-VkImportFenceFdInfoKHR-handleType-parameter
    handleType must be a valid VkExternalFenceHandleTypeFlagBits value

Host Synchronization
  • Host access to fence must be externally synchronized

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.

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SPDX-License-Identifier: CC-BY-4.0