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 <div class="title">VK_AMD_device_coherent_memory </div>  </div>
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 <div class="textblock"><p>VK_AMD_device_coherent_memory is a device extension that enables access to additional memory types with <code>VK_MEMORY_PROPERTY_DEVICE_COHERENT_BIT_AMD</code> and <code>VK_MEMORY_PROPERTY_DEVICE_UNCACHED_BIT_AMD</code> flag. It is useful mostly for allocation of buffers intended for writing "breadcrumb markers" in between passes or draw calls, which in turn are useful for debugging GPU crash/hang/TDR cases.</p>
 <p>When the extension is available but has not been enabled, Vulkan physical device still exposes those memory types, but their usage is forbidden. VMA automatically takes care of that - it returns <code>VK_ERROR_FEATURE_NOT_PRESENT</code> when an attempt to allocate memory of such type is made.</p>
 <p>If you want to use this extension in connection with VMA, follow these steps:</p>
 <h1><a class="anchor" id="vk_amd_device_coherent_memory_initialization"></a>
 Initialization</h1>
 <p>1) Call <code>vkEnumerateDeviceExtensionProperties</code> for the physical device. Check if the extension is supported - if returned array of <code>VkExtensionProperties</code> contains "VK_AMD_device_coherent_memory".</p>
 <p>2) Call <code>vkGetPhysicalDeviceFeatures2</code> for the physical device instead of old <code>vkGetPhysicalDeviceFeatures</code>. Attach additional structure <code>VkPhysicalDeviceCoherentMemoryFeaturesAMD</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> to be returned. Check if the device feature is really supported - check if <code>VkPhysicalDeviceCoherentMemoryFeaturesAMD::deviceCoherentMemory</code> is true.</p>
 <p>3) While creating device with <code>vkCreateDevice</code>, enable this extension - add "VK_AMD_device_coherent_memory" to the list passed as <code>VkDeviceCreateInfo::ppEnabledExtensionNames</code>.</p>
 <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>VkPhysicalDeviceCoherentMemoryFeaturesAMD</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> and set its member <code>deviceCoherentMemory</code> to <code>VK_TRUE</code>.</p>
 <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 extension and feature - add <a class="el" href="vk__mem__alloc_8h.html#a4f87c9100d154a65a4ad495f7763cf7ca2acce4886d8078552efa38878413970f">VMA_ALLOCATOR_CREATE_AMD_DEVICE_COHERENT_MEMORY_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>
 <h1><a class="anchor" id="vk_amd_device_coherent_memory_usage"></a>
 Usage</h1>
 <p>After following steps described above, you can create VMA allocations and custom pools out of the special <code>DEVICE_COHERENT</code> and <code>DEVICE_UNCACHED</code> memory types on eligible devices. There are multiple ways to do it, for example:</p>
 <ul>
 <li>You can request or prefer to allocate out of such memory types by adding <code>VK_MEMORY_PROPERTY_DEVICE_COHERENT_BIT_AMD</code> to <a class="el" href="struct_vma_allocation_create_info.html#a9166390303ff42d783305bc31c2b6b90" title="Flags that must be set in a Memory Type chosen for an allocation.">VmaAllocationCreateInfo::requiredFlags</a> or <a class="el" href="struct_vma_allocation_create_info.html#a7fe8d81a1ad10b2a2faacacee5b15d6d" title="Flags that preferably should be set in a memory type chosen for an allocation.">VmaAllocationCreateInfo::preferredFlags</a>. Those flags can be freely mixed with other ways of <a class="el" href="choosing_memory_type.html">Choosing memory type</a>, like setting <a class="el" href="struct_vma_allocation_create_info.html#accb8b06b1f677d858cb9af20705fa910" title="Intended usage of memory.">VmaAllocationCreateInfo::usage</a>.</li>
 <li>If you manually found memory type index to use for this purpose, force allocation from this specific index by setting <a class="el" href="struct_vma_allocation_create_info.html#a3bf940c0271d85d6ba32a4d820075055" title="Bitmask containing one bit set for every memory type acceptable for this allocation.">VmaAllocationCreateInfo::memoryTypeBits</a> <code>= 1u &lt;&lt; index</code>.</li>
 </ul>
 <h1><a class="anchor" id="vk_amd_device_coherent_memory_more_information"></a>
 More information</h1>
 <p>To learn more about this extension, see <a href="https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/chap44.html#VK_AMD_device_coherent_memory">VK_AMD_device_coherent_memory in Vulkan specification</a></p>
 <p>Example use of this extension can be found in the code of the sample and test suite accompanying this library. </p>
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	<div class="title">VK_AMD_device_coherent_memory </div> </div>
	</div><!--header-->
	<div class="contents">
	<div class="textblock"><p>VK_AMD_device_coherent_memory is a device extension that enables access to additional memory types with <code>VK_MEMORY_PROPERTY_DEVICE_COHERENT_BIT_AMD</code> and <code>VK_MEMORY_PROPERTY_DEVICE_UNCACHED_BIT_AMD</code> flag. It is useful mostly for allocation of buffers intended for writing "breadcrumb markers" in between passes or draw calls, which in turn are useful for debugging GPU crash/hang/TDR cases.</p>
	<p>When the extension is available but has not been enabled, Vulkan physical device still exposes those memory types, but their usage is forbidden. VMA automatically takes care of that - it returns <code>VK_ERROR_FEATURE_NOT_PRESENT</code> when an attempt to allocate memory of such type is made.</p>
	<p>If you want to use this extension in connection with VMA, follow these steps:</p>
	<h1><a class="anchor" id="vk_amd_device_coherent_memory_initialization"></a>
	Initialization</h1>
	<p>1) Call <code>vkEnumerateDeviceExtensionProperties</code> for the physical device. Check if the extension is supported - if returned array of <code>VkExtensionProperties</code> contains "VK_AMD_device_coherent_memory".</p>
	<p>2) Call <code>vkGetPhysicalDeviceFeatures2</code> for the physical device instead of old <code>vkGetPhysicalDeviceFeatures</code>. Attach additional structure <code>VkPhysicalDeviceCoherentMemoryFeaturesAMD</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> to be returned. Check if the device feature is really supported - check if <code>VkPhysicalDeviceCoherentMemoryFeaturesAMD::deviceCoherentMemory</code> is true.</p>
	<p>3) While creating device with <code>vkCreateDevice</code>, enable this extension - add "VK_AMD_device_coherent_memory" to the list passed as <code>VkDeviceCreateInfo::ppEnabledExtensionNames</code>.</p>
	<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>VkPhysicalDeviceCoherentMemoryFeaturesAMD</code> to <code>VkPhysicalDeviceFeatures2::pNext</code> and set its member <code>deviceCoherentMemory</code> to <code>VK_TRUE</code>.</p>
	<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 extension and feature - add <a class="el" href="vk__mem__alloc_8h.html#a4f87c9100d154a65a4ad495f7763cf7ca2acce4886d8078552efa38878413970f">VMA_ALLOCATOR_CREATE_AMD_DEVICE_COHERENT_MEMORY_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>
	<h1><a class="anchor" id="vk_amd_device_coherent_memory_usage"></a>
	Usage</h1>
	<p>After following steps described above, you can create VMA allocations and custom pools out of the special <code>DEVICE_COHERENT</code> and <code>DEVICE_UNCACHED</code> memory types on eligible devices. There are multiple ways to do it, for example:</p>
	<ul>
	<li>You can request or prefer to allocate out of such memory types by adding <code>VK_MEMORY_PROPERTY_DEVICE_COHERENT_BIT_AMD</code> to <a class="el" href="struct_vma_allocation_create_info.html#a9166390303ff42d783305bc31c2b6b90" title="Flags that must be set in a Memory Type chosen for an allocation.">VmaAllocationCreateInfo::requiredFlags</a> or <a class="el" href="struct_vma_allocation_create_info.html#a7fe8d81a1ad10b2a2faacacee5b15d6d" title="Flags that preferably should be set in a memory type chosen for an allocation.">VmaAllocationCreateInfo::preferredFlags</a>. Those flags can be freely mixed with other ways of <a class="el" href="choosing_memory_type.html">Choosing memory type</a>, like setting <a class="el" href="struct_vma_allocation_create_info.html#accb8b06b1f677d858cb9af20705fa910" title="Intended usage of memory.">VmaAllocationCreateInfo::usage</a>.</li>
	<li>If you manually found memory type index to use for this purpose, force allocation from this specific index by setting <a class="el" href="struct_vma_allocation_create_info.html#a3bf940c0271d85d6ba32a4d820075055" title="Bitmask containing one bit set for every memory type acceptable for this allocation.">VmaAllocationCreateInfo::memoryTypeBits</a> <code>= 1u << index</code>.</li>
	</ul>
	<h1><a class="anchor" id="vk_amd_device_coherent_memory_more_information"></a>
	More information</h1>
	<p>To learn more about this extension, see <a href="https://www.khronos.org/registry/vulkan/specs/1.2-extensions/html/chap44.html#VK_AMD_device_coherent_memory">VK_AMD_device_coherent_memory in Vulkan specification</a></p>
	<p>Example use of this extension can be found in the code of the sample and test suite accompanying this library. </p>
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