# vkCmdUpdateBuffer(3) Manual Page

## Name

vkCmdUpdateBuffer - Update a buffer's contents from host memory

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## C Specification

To update buffer data inline in a command buffer, call:

    // Provided by VK_VERSION_1_0
    void vkCmdUpdateBuffer(
        VkCommandBuffer                             commandBuffer,
        VkBuffer                                    dstBuffer,
        VkDeviceSize                                dstOffset,
        VkDeviceSize                                dataSize,
        const void*                                 pData);

## Parameters

- `commandBuffer` is the command buffer into which the command will be recorded.

- `dstBuffer` is a handle to the buffer to be updated.

- `dstOffset` is the byte offset into the buffer to start updating, and must be a multiple of 4.

- `dataSize` is the number of bytes to update, and must be a multiple of 4.

- `pData` is a pointer to the source data for the buffer update, and must be at least `dataSize` bytes in size.

## Description

`dataSize` must be less than or equal to 65536 bytes. For larger updates, applications can use buffer to buffer copies.

Note | Buffer updates performed with `vkCmdUpdateBuffer` first copy the data into command buffer memory when the command is recorded (which requires additional storage and may incur an additional allocation), and then copy the data from the command buffer into `dstBuffer` when the command is executed on a device. The additional cost of this functionality compared to buffer to buffer copies means it should only be used for very small amounts of data, and is why it is limited to at most 65536 bytes. Applications can work around this restriction by issuing multiple `vkCmdUpdateBuffer` commands to different ranges of the same buffer, but doing so is not recommended.

The source data is copied from `pData` to the command buffer when the command is called.

`vkCmdUpdateBuffer` is only allowed outside of a render pass. This command is treated as a “transfer” operation for the purposes of synchronization barriers. The `VK_BUFFER_USAGE_TRANSFER_DST_BIT` must be specified in `usage` of VkBufferCreateInfo in order for the buffer to be compatible with `vkCmdUpdateBuffer`.

Valid Usage

- VUID-vkCmdUpdateBuffer-dstOffset-00032
  `dstOffset` must be less than the size of `dstBuffer`

- VUID-vkCmdUpdateBuffer-dataSize-00033
  `dataSize` must be less than or equal to the size of `dstBuffer` minus `dstOffset`

- VUID-vkCmdUpdateBuffer-dstBuffer-00034
  `dstBuffer` must have been created with `VK_BUFFER_USAGE_TRANSFER_DST_BIT` usage flag

- VUID-vkCmdUpdateBuffer-dstBuffer-00035
  If `dstBuffer` is non-sparse then it must be bound completely and contiguously to a single `VkDeviceMemory` object

- VUID-vkCmdUpdateBuffer-dstOffset-00036
  `dstOffset` must be a multiple of `4`

- VUID-vkCmdUpdateBuffer-dataSize-00037
  `dataSize` must be less than or equal to `65536`

- VUID-vkCmdUpdateBuffer-dataSize-00038
  `dataSize` must be a multiple of `4`

- VUID-vkCmdUpdateBuffer-commandBuffer-01813
  If `commandBuffer` is an unprotected command buffer and `protectedNoFault` is not supported, `dstBuffer` must not be a protected buffer

- VUID-vkCmdUpdateBuffer-commandBuffer-01814
  If `commandBuffer` is a protected command buffer and `protectedNoFault` is not supported, `dstBuffer` must not be an unprotected buffer

Valid Usage (Implicit)

- VUID-vkCmdUpdateBuffer-commandBuffer-parameter
  `commandBuffer` must be a valid VkCommandBuffer handle

- VUID-vkCmdUpdateBuffer-dstBuffer-parameter
  `dstBuffer` must be a valid VkBuffer handle

- VUID-vkCmdUpdateBuffer-pData-parameter
  `pData` must be a valid pointer to an array of `dataSize` bytes

- VUID-vkCmdUpdateBuffer-commandBuffer-recording
  `commandBuffer` must be in the recording state

- VUID-vkCmdUpdateBuffer-commandBuffer-cmdpool
  The `VkCommandPool` that `commandBuffer` was allocated from must support transfer, graphics, or compute operations

- VUID-vkCmdUpdateBuffer-renderpass
  This command must only be called outside of a render pass instance

- VUID-vkCmdUpdateBuffer-videocoding
  This command must only be called outside of a video coding scope

- VUID-vkCmdUpdateBuffer-dataSize-arraylength
  `dataSize` must be greater than `0`

- VUID-vkCmdUpdateBuffer-commonparent
  Both of `commandBuffer`, and `dstBuffer` must have been created, allocated, or retrieved from the same VkDevice

Host Synchronization

- Host access to `commandBuffer` must be externally synchronized

- Host access to the `VkCommandPool` that `commandBuffer` was allocated from must be externally synchronized

Command Properties

Command Buffer Levels | Render Pass Scope | Video Coding Scope | Supported Queue Types | Command Type
--- | --- | --- | --- | ---
Primary Secondary | Outside | Outside | Transfer Graphics Compute | Action

## See Also

VK_VERSION_1_0, VkBuffer, VkCommandBuffer, VkDeviceSize

## 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

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0