Does cl_khr_external_memory and its sub-extensions mandate support for the creation of both buffer and image memory objects?

[lengleng1992]

@bashbaug @kpet
Considering that hardware may have limitations on the memory layout of images, does cl_khr_external_memory allow implementations to support only the creation of buffer objects?
If so, how can users query the types of memory objects (only buffer、only image、both) supported by this extension?

[nikhiljnv]

Does cl_khr_external_memory allow implementations to support only the creation of buffer objects?
--> If an implementation/device supports images (https://registry.khronos.org/OpenCL/specs/3.0-unified/html/OpenCL_API.html#CL_DEVICE_IMAGE_SUPPORT), it must support importing external memory as images as part of cl_khr_external_memory.

[nikhiljnv]

You may also find this query useful which returns the list of importable external memory handle types supported by device, that are assumed to apply linear layout to imported images when no other tiling information is provided.
https://registry.khronos.org/OpenCL/specs/3.0-unified/html/OpenCL_API.html#CL_DEVICE_EXTERNAL_MEMORY_IMPORT_ASSUME_LINEAR_IMAGES_HANDLE_TYPES_KHR

Additionally, we are discussing image tiling control and DRM format modifier extensions which should help add mechanisms to specify the tiling information more precisely.
#710
#1019

[bashbaug]

Confirmed in the April 1st memory subgroup. If an implementation supports images then it needs to support creating both buffer and image memory objects using external memory handles, for the external memory handle types the implementation reports.

Feel free to ask an additional question or re-open this issue if this is a problem.