## C Specification

The VkQueueFamilyProperties structure is defined as:

// Provided by VK_VERSION_1_0
typedef struct VkQueueFamilyProperties {
VkQueueFlags    queueFlags;
uint32_t        queueCount;
uint32_t        timestampValidBits;
VkExtent3D      minImageTransferGranularity;
} VkQueueFamilyProperties;

## Members

• queueFlags is a bitmask of VkQueueFlagBits indicating capabilities of the queues in this queue family.

• queueCount is the unsigned integer count of queues in this queue family. Each queue family must support at least one queue.

• timestampValidBits is the unsigned integer count of meaningful bits in the timestamps written via vkCmdWriteTimestamp2KHR or vkCmdWriteTimestamp. The valid range for the count is 36..64 bits, or a value of 0, indicating no support for timestamps. Bits outside the valid range are guaranteed to be zeros.

• minImageTransferGranularity is the minimum granularity supported for image transfer operations on the queues in this queue family.

## Description

The value returned in minImageTransferGranularity has a unit of compressed texel blocks for images having a block-compressed format, and a unit of texels otherwise.

Possible values of minImageTransferGranularity are:

• (0,0,0) specifies that only whole mip levels must be transferred using the image transfer operations on the corresponding queues. In this case, the following restrictions apply to all offset and extent parameters of image transfer operations:

• The x, y, and z members of a VkOffset3D parameter must always be zero.

• The width, height, and depth members of a VkExtent3D parameter must always match the width, height, and depth of the image subresource corresponding to the parameter, respectively.

• (Ax, Ay, Az) where Ax, Ay, and Az are all integer powers of two. In this case the following restrictions apply to all image transfer operations:

• x, y, and z of a VkOffset3D parameter must be integer multiples of Ax, Ay, and Az, respectively.

• width of a VkExtent3D parameter must be an integer multiple of Ax, or else x + width must equal the width of the image subresource corresponding to the parameter.

• height of a VkExtent3D parameter must be an integer multiple of Ay, or else y + height must equal the height of the image subresource corresponding to the parameter.

• depth of a VkExtent3D parameter must be an integer multiple of Az, or else z + depth must equal the depth of the image subresource corresponding to the parameter.

• If the format of the image corresponding to the parameters is one of the block-compressed formats then for the purposes of the above calculations the granularity must be scaled up by the compressed texel block dimensions.

Queues supporting graphics and/or compute operations must report (1,1,1) in minImageTransferGranularity, meaning that there are no additional restrictions on the granularity of image transfer operations for these queues. Other queues supporting image transfer operations are only required to support whole mip level transfers, thus minImageTransferGranularity for queues belonging to such queue families may be (0,0,0).

The Device Memory section describes memory properties queried from the physical device.

For physical device feature queries see the Features chapter.

## Document Notes

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

Copyright 2014-2021 The Khronos Group Inc.