C Specification

Data can be retrieved from a validation cache object using the command:

// Provided by VK_EXT_validation_cache
VkResult vkGetValidationCacheDataEXT(
    VkDevice                                    device,
    VkValidationCacheEXT                        validationCache,
    size_t*                                     pDataSize,
    void*                                       pData);


  • device is the logical device that owns the validation cache.

  • validationCache is the validation cache to retrieve data from.

  • pDataSize is a pointer to a value related to the amount of data in the validation cache, as described below.

  • pData is either NULL or a pointer to a buffer.


If pData is NULL, then the maximum size of the data that can be retrieved from the validation cache, in bytes, is returned in pDataSize. Otherwise, pDataSize must point to a variable set by the user to the size of the buffer, in bytes, pointed to by pData, and on return the variable is overwritten with the amount of data actually written to pData. If pDataSize is less than the maximum size that can be retrieved by the validation cache, at most pDataSize bytes will be written to pData, and vkGetValidationCacheDataEXT will return VK_INCOMPLETE instead of VK_SUCCESS, to indicate that not all of the validation cache was returned.

Any data written to pData is valid and can be provided as the pInitialData member of the VkValidationCacheCreateInfoEXT structure passed to vkCreateValidationCacheEXT.

Two calls to vkGetValidationCacheDataEXT with the same parameters must retrieve the same data unless a command that modifies the contents of the cache is called between them.

Applications can store the data retrieved from the validation cache, and use these data, possibly in a future run of the application, to populate new validation cache objects. The results of validation, however, may depend on the vendor ID, device ID, driver version, and other details of the device. To enable applications to detect when previously retrieved data is incompatible with the device, the initial bytes written to pData must be a header consisting of the following members:

Table 1. Layout for validation cache header version VK_VALIDATION_CACHE_HEADER_VERSION_ONE_EXT
Offset Size Meaning



length in bytes of the entire validation cache header written as a stream of bytes, with the least significant byte first



a VkValidationCacheHeaderVersionEXT value written as a stream of bytes, with the least significant byte first



a layer commit ID expressed as a UUID, which uniquely identifies the version of the validation layers used to generate these validation results

The first four bytes encode the length of the entire validation cache header, in bytes. This value includes all fields in the header including the validation cache version field and the size of the length field.

The next four bytes encode the validation cache version, as described for VkValidationCacheHeaderVersionEXT. A consumer of the validation cache should use the cache version to interpret the remainder of the cache header.

If pDataSize is less than what is necessary to store this header, nothing will be written to pData and zero will be written to pDataSize.

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

  • VUID-vkGetValidationCacheDataEXT-validationCache-parameter
    validationCache must be a valid VkValidationCacheEXT handle

  • VUID-vkGetValidationCacheDataEXT-pDataSize-parameter
    pDataSize must be a valid pointer to a size_t value

  • VUID-vkGetValidationCacheDataEXT-pData-parameter
    If the value referenced by pDataSize is not 0, and pData is not NULL, pData must be a valid pointer to an array of pDataSize bytes

  • VUID-vkGetValidationCacheDataEXT-validationCache-parent
    validationCache must have been created, allocated, or retrieved from device

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 2014-2022 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0