## C Specification

The VkImportSemaphoreFdInfoKHR structure is defined as:

// Provided by VK_KHR_external_semaphore_fd
typedef struct VkImportSemaphoreFdInfoKHR {
VkStructureType                          sType;
const void*                              pNext;
VkSemaphore                              semaphore;
VkSemaphoreImportFlags                   flags;
VkExternalSemaphoreHandleTypeFlagBits    handleType;
int                                      fd;
} VkImportSemaphoreFdInfoKHR;

## Members

• sType is the type of this structure.

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

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

• flags is a bitmask of VkSemaphoreImportFlagBits specifying additional parameters for the semaphore payload import operation.

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

• fd is the external handle to import.

## Description

The handle types supported by handleType are:

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

VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT

Reference

Temporary,Permanent

VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT

Copy

Temporary

Valid Usage
• VUID-VkImportSemaphoreFdInfoKHR-handleType-01143
handleType must be a value included in the Handle Types Supported by VkImportSemaphoreFdInfoKHR table

• VUID-VkImportSemaphoreFdInfoKHR-fd-01544
fd must obey any requirements listed for handleType in external semaphore handle types compatibility

• VUID-VkImportSemaphoreFdInfoKHR-handleType-03263
If handleType is VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT, the VkSemaphoreCreateInfo::flags field must match that of the semaphore from which fd was exported

• VUID-VkImportSemaphoreFdInfoKHR-handleType-03264
If handleType is VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_OPAQUE_FD_BIT, the VkSemaphoreTypeCreateInfo::semaphoreType field must match that of the semaphore from which fd was exported

• VUID-VkImportSemaphoreFdInfoKHR-flags-03323
If flags contains VK_SEMAPHORE_IMPORT_TEMPORARY_BIT, the VkSemaphoreTypeCreateInfo::semaphoreType field of the semaphore from which fd was exported must not be VK_SEMAPHORE_TYPE_TIMELINE

If handleType is VK_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 VkSemaphore 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 VK_EXTERNAL_SEMAPHORE_HANDLE_TYPE_SYNC_FD_BIT from a VkSemaphore which is signaled.
Valid Usage (Implicit)
• VUID-VkImportSemaphoreFdInfoKHR-sType-sType
sType must be VK_STRUCTURE_TYPE_IMPORT_SEMAPHORE_FD_INFO_KHR

• VUID-VkImportSemaphoreFdInfoKHR-pNext-pNext
pNext must be NULL

• VUID-VkImportSemaphoreFdInfoKHR-semaphore-parameter
semaphore must be a valid VkSemaphore handle

• VUID-VkImportSemaphoreFdInfoKHR-flags-parameter
flags must be a valid combination of VkSemaphoreImportFlagBits values

• VUID-VkImportSemaphoreFdInfoKHR-handleType-parameter
handleType must be a valid VkExternalSemaphoreHandleTypeFlagBits value

Host Synchronization
• Host access to semaphore must be externally synchronized