1<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 2<html xmlns="http://www.w3.org/1999/xhtml"> 3<head> 4<meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> 5<meta http-equiv="X-UA-Compatible" content="IE=9"/> 6<meta name="generator" content="Doxygen 1.8.17"/> 7<meta name="viewport" content="width=device-width, initial-scale=1"/> 8<title>Vulkan Memory Allocator: Enabling buffer device address</title> 9<link href="tabs.css" rel="stylesheet" type="text/css"/> 10<script type="text/javascript" src="jquery.js"></script> 11<script type="text/javascript" src="dynsections.js"></script> 12<link href="search/search.css" rel="stylesheet" type="text/css"/> 13<script type="text/javascript" src="search/searchdata.js"></script> 14<script type="text/javascript" src="search/search.js"></script> 15<link href="doxygen.css" rel="stylesheet" type="text/css" /> 16</head> 17<body> 18<div id="top"><!-- do not remove this div, it is closed by doxygen! --> 19<div id="titlearea"> 20<table cellspacing="0" cellpadding="0"> 21 <tbody> 22 <tr style="height: 56px;"> 23 <td id="projectalign" style="padding-left: 0.5em;"> 24 <div id="projectname">Vulkan Memory Allocator 25 </div> 26 </td> 27 </tr> 28 </tbody> 29</table> 30</div> 31<!-- end header part --> 32<!-- Generated by Doxygen 1.8.17 --> 33<script type="text/javascript"> 34/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ 35var searchBox = new SearchBox("searchBox", "search",false,'Search'); 36/* @license-end */ 37</script> 38<script type="text/javascript" src="menudata.js"></script> 39<script type="text/javascript" src="menu.js"></script> 40<script type="text/javascript"> 41/* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ 42$(function() { 43 initMenu('',true,false,'search.php','Search'); 44 $(document).ready(function() { init_search(); }); 45}); 46/* @license-end */</script> 47<div id="main-nav"></div> 48<!-- window showing the filter options --> 49<div id="MSearchSelectWindow" 50 onmouseover="return searchBox.OnSearchSelectShow()" 51 onmouseout="return searchBox.OnSearchSelectHide()" 52 onkeydown="return searchBox.OnSearchSelectKey(event)"> 53</div> 54 55<!-- iframe showing the search results (closed by default) --> 56<div id="MSearchResultsWindow"> 57<iframe src="javascript:void(0)" frameborder="0" 58 name="MSearchResults" id="MSearchResults"> 59</iframe> 60</div> 61 62<div id="nav-path" class="navpath"> 63 <ul> 64<li class="navelem"><a class="el" href="index.html">Vulkan Memory Allocator</a></li> </ul> 65</div> 66</div><!-- top --> 67<div class="PageDoc"><div class="header"> 68 <div class="headertitle"> 69<div class="title">Enabling buffer device address </div> </div> 70</div><!--header--> 71<div class="contents"> 72<div class="textblock"><p>Device extension VK_KHR_buffer_device_address allow to fetch raw GPU pointer to a buffer and pass it for usage in a shader code. It is promoted to core Vulkan 1.2.</p> 73<p>If you want to use this feature in connection with VMA, follow these steps:</p> 74<h1><a class="anchor" id="enabling_buffer_device_address_initialization"></a> 75Initialization</h1> 76<p>1) (For Vulkan version < 1.2) Call <code>vkEnumerateDeviceExtensionProperties</code> for the physical device. Check if the extension is supported - if returned array of <code>VkExtensionProperties</code> contains "VK_KHR_buffer_device_address".</p> 77<p>2) Call <code>vkGetPhysicalDeviceFeatures2</code> for the physical device instead of old <code>vkGetPhysicalDeviceFeatures</code>. Attach additional structure <code>VkPhysicalDeviceBufferDeviceAddressFeatures*</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> to be returned. Check if the device feature is really supported - check if <code>VkPhysicalDeviceBufferDeviceAddressFeatures*::bufferDeviceAddress</code> is true.</p> 78<p>3) (For Vulkan version < 1.2) While creating device with <code>vkCreateDevice</code>, enable this extension - add "VK_KHR_buffer_device_address" to the list passed as <code>VkDeviceCreateInfo::ppEnabledExtensionNames</code>.</p> 79<p>4) While creating the device, also don't set <code>VkDeviceCreateInfo::pEnabledFeatures</code>. Fill in <code>VkPhysicalDeviceFeatures2</code> structure instead and pass it as <code>VkDeviceCreateInfo::pNext</code>. Enable this device feature - attach additional structure <code>VkPhysicalDeviceBufferDeviceAddressFeatures*</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> and set its member <code>bufferDeviceAddress</code> to <code>VK_TRUE</code>.</p> 80<p>5) While creating <a class="el" href="struct_vma_allocator.html" title="Represents main object of this library initialized.">VmaAllocator</a> with <a class="el" href="vk__mem__alloc_8h.html#a200692051ddb34240248234f5f4c17bb" title="Creates Allocator object.">vmaCreateAllocator()</a> inform VMA that you have enabled this feature - add <a class="el" href="vk__mem__alloc_8h.html#a4f87c9100d154a65a4ad495f7763cf7ca5f1b28b0414319d1687e1f2b30ab0089">VMA_ALLOCATOR_CREATE_BUFFER_DEVICE_ADDRESS_BIT</a> to <a class="el" href="struct_vma_allocator_create_info.html#a392ea2ecbaff93f91a7c49f735ad4346" title="Flags for created allocator. Use VmaAllocatorCreateFlagBits enum.">VmaAllocatorCreateInfo::flags</a>.</p> 81<h1><a class="anchor" id="enabling_buffer_device_address_usage"></a> 82Usage</h1> 83<p>After following steps described above, you can create buffers with <code>VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT*</code> using VMA. The library automatically adds <code>VK_MEMORY_ALLOCATE_DEVICE_ADDRESS_BIT*</code> to allocated memory blocks wherever it might be needed.</p> 84<p>Please note that the library supports only <code>VK_BUFFER_USAGE_SHADER_DEVICE_ADDRESS_BIT*</code>. The second part of this functionality related to "capture and replay" is not supported, as it is intended for usage in debugging tools like RenderDoc, not in everyday Vulkan usage.</p> 85<h1><a class="anchor" id="enabling_buffer_device_address_more_information"></a> 86More information</h1> 87<p>To learn more about this extension, see <a href="https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/chap46.html#VK_KHR_buffer_device_address">VK_KHR_buffer_device_address in Vulkan specification</a></p> 88<p>Example use of this extension can be found in the code of the sample and test suite accompanying this library. </p> 89</div></div><!-- contents --> 90</div><!-- PageDoc --> 91<!-- start footer part --> 92<hr class="footer"/><address class="footer"><small> 93Generated by  <a href="http://www.doxygen.org/index.html"> 94<img class="footer" src="doxygen.png" alt="doxygen"/> 95</a> 1.8.17 96</small></address> 97</body> 98</html> 99
