AMDGPU XGMI Support

AMDGPU XGMI Support

XGMI is a high speed interconnect that joins multiple GPU cards into a homogeneous memory space that is organized by a collective hive ID and individual node IDs, both of which are 64-bit numbers.

The file xgmi_device_id contains the unique per GPU device ID and is stored in the /sys/class/drm/card${cardno}/device/ directory.

Inside the device directory a sub-directory ‘xgmi_hive_info’ is created which contains the hive ID and the list of nodes.

The hive ID is stored in:
/sys/class/drm/card${cardno}/device/xgmi_hive_info/xgmi_hive_id
The node information is stored in numbered directories:
/sys/class/drm/card${cardno}/device/xgmi_hive_info/node${nodeno}/xgmi_device_id

Each device has their own xgmi_hive_info direction with a mirror set of node sub-directories.

The XGMI memory space is built by contiguously adding the power of two padded VRAM space from each node to each other.