The description of A2 standard features sounds very similar to the new Linux multi-queue block device framework.

From quick look at latest Linux source code, there are couple mentions of "blk_mq" in drivers/mmc, but there seems to be no actual support for multiple queues (unlike e.g. in drivers/nvme).

Does anyone know, if those are supposed to be same things? Does SD driver actually need new firmware to support multiple queues or is it something, that can be implemented on kernel side in software only? At the very least, it might be possible to use a third-party reader as long as it's kernel drivers are updated to take advantage of multiple command queues.