doc: Add initial documentation for nvme hotplug.

                         nvme/async_completion.md \

                         nvme/fabrics.md \

                         nvme/initialization.md \

                         nvme/hotplug.md \

                         nvme/io_submission.md \

                         nvme/multi_process.md \

                         nvmf/index.md \

# NVMe Hotplug {#nvme_hotplug}

At the NVMe driver level, we provide the following support for Hotplug:

1. Hotplug events detection:

The user of the NVMe library can call spdk_nvme_probe() periodically to detect

hotplug events. The probe_cb, followed by the attach_cb, will be called for each

new device detected. The user may optionally also provide a remove_cb that will be

called if a previously attached NVMe device is no longer present on the system.

All subsequent I/O to the removed device will return an error.

2. Hot remove NVMe with IO loads:

When a device is hot removed while I/O is occurring, all access to the PCI BAR will

result in a SIGBUS error. The NVMe driver automatically handles this case by installing

a SIGBUS handler and remapping the PCI BAR to a new, placeholder memory location.

This means I/O in flight during a hot remove will complete with an appropriate error

code and will not crash the application.

@sa spdk_nvme_probe

- @ref nvme_async_completion

- @ref nvme_fabrics_host

- @ref nvme_multi_process

- @ref nvme_hotplug