DRA Device Compatibility Groups

This KEP proposes an extension to the Dynamic Resource Allocation (DRA) ResourceSlice API to support mutually exclusive device allocation constraints between sets of devices. Hardware devices often support multiple partitioning or virtualization schemes (for example, GPU MIG slicing vs. vGPU profiles) that provide different trade-offs in terms of isolation, performance, and resource sharing. These schemes are frequently mutually exclusive at the hardware level: once a physical device is partitioned or configured using one scheme, it cannot be reconfigured to use a different scheme until all existing allocations are released. The current DRA Partitionable Devices API has no mechanism for drivers to express these mutual exclusivity constraints. A shared counter with a capacity of one can ensure mutual exclusion, but this cannot be used here: such a counter would have to be decremented once when allocating the first device from a set of compatible devices, not once for each device. This cannot be expressed at the moment.