I have a question regarding the M.2 Sata hotplug capability. I'm running Arch Linux with up-to-date kernel (4.4).
I have a above mentioned NUC and I use M.2 to Sata conversion board. I can use that to add additional Sata drive if I provide external power for the drive.
I have the Sata hotplug option enabled in BIOS. It works fine for the internal Sata port, but doesn't work for the M.2 Sata port.
If I boot with the M.2 Sata drive present, then unplug and replug, it will get detected correctly.
If I boot without the M.2 Sata drive present, then any hot plug is not detected.
Is this intentional? Or bug? Is there any way this behaviour can be modified to enable the hotplug on the M.2 Sata port as well?
To the best of my knowledge, the hot-plug feature is intended to support cabled SATA to USB drives or cabled SD to USB drives attached externally to a USB external port. The internal drives are intended to be fixed.