We have been doing a R&D work related to the NVMe controller on Mac platform, where we need to get control of the admin queues(submission as well as completion). From the spec of NVMe it’s very clear that what are all registers do we need to deal with to get access of the queues. We are accordingly following those registers to create our own queues. Also we have prepared and enqueued a sample admin command to the newly created submission queue. But surprisingly we can’t get any assurance whether the command got processed by the controller or not, because from the completion queue entry we can see all the entries are zero, which is not expected anyway. So here the question is, how to communicate with the controller properly ? We are also aware of the fact of existing NVMe driver(IONVMeFamily) on Mac platform, is this somehow crossing our way ? We have done all the proper setup for registers, DMAs and interrupt. Path is very ok if we use builtin driver with the XNVME user space application (we can trigger limited admin commands over there). But here we need to have our own created queues up and running with seamless admin command transaction. Here we must tell about our setup, we have one SSD which is connected via a thunderbolt cable to Mac laptop using type C usb port. We have tried to access pre-configured admin queues from IONVMeFamily driver but that is also a blocker for us, as we can’t see any valid data from submission/completion queues.
Request you to all please help us coming out of this trapped zone.