At Vulkan specs 1.0.9 (pg. 180), we have the following:
typedef struct VkMemoryHeap {
VkDeviceSize size;
VkMemoryHeapFlags flags;
} VkMemoryHeap;
and this description:
• size is the total memory size in bytes in the heap.
• flags is a bitmask of attribute flags for the heap. The bits specified in flags are:
typedef enum VkMemoryHeapFlagBits {
VK_MEMORY_HEAP_DEVICE_LOCAL_BIT = 0x00000001,
} VkMemoryHeapFlagBits;
But when I query VkPhysicalDeviceMemoryProperties
I've got flags with zero values. My code matches the output from Vulkan SDK vkjson_info.exe tool, which output a JSON file with properties from my GPU.
Is something missing here ?
No. It is perfectly valid for VkMemoryHeap::flags
to be 0. A particular flag is either present or absent; it's not an enumeration where the value can attain one of a small number of different possibilities. Usually, flags are independent of one another.
That's how bitflags work; they represent boolean conditions. A particular flag is either present or absent. If a flag is present, then the object attains the meaning that the flag defines. If it is absent, then the object doesn't have that meaning.
A heap with VK_MEMORY_HEAP_DEVICE_LOCAL_BIT
means exactly what the specification says it means: "the heap corresponds to device local memory". A heap without that flag set means that heap does not "correspond to device local memory".
The specification requires that at least one heap have this flag set. But that's all.
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