问题
On POSIX systems, one can import memory objects from other APIs through file descriptors using VkImportMemoryFdInfoKHR (it works similarly on Windows using VkImportMemoryWin32HandleInfoKHR). Once the memory object has been imported, is Vulkan allowed to free the underlying memory with vkFreeMemory, or can the memory only be freed by the API that has allocated it? Thank you for your help!
回答1:
Vulkan is not merely allowed to free the VkDeviceMemory object; it is required to do so. When you import memory into Vulkan, the specification is clear that Vulkan now owns that handle:
Importing memory from a file descriptor transfers ownership of the file descriptor from the application to the Vulkan implementation. The application must not perform any operations on the file descriptor after a successful import.
So you're not allowed to use regular commands on that file descriptor anymore. Vulkan owns it, and calling vkFreeMemory on it is not optional:
VkDevice objects can be destroyed when all VkQueue objects retrieved from them are idle, and all objects created from them have been destroyed. This includes the following objects:
...
- VkDeviceMemory
No exception is made for VkDeviceMemory objects allocated as the result of an memory import operation.
Now of course, you can perform operations on a different FD that just so happens to be talking to the same memory (you can even use vkGetMemoryFdKHR to do so). But the specific FD you imported becomes owned by Vulkan. Freeing the memory frees the file descriptor; it doesn't affect the memory itself.
来源：https://stackoverflow.com/questions/59444668/can-memory-imported-to-vulkan-from-another-api-be-freed-by-vulkan