I bought a M.2 M-key NVMe SSD few day back. It's a PCIe 3.0 (i.e., 8 Gbps) 2-lane NVMe 128GB SSD. It's a low end such that I know it only supports 2-lane PCIe (due to its inexpensive storage controller RT5760.) The item is XPG SX6000 128GB M.2 PCIe NVMe (Newegg was selling for $33 free shipping.) I first tried it on a PC that has a M-key NGFF M.2 slot. Its UEFI BIOS detected it right away and allowed me installing UBUNTU on it without any problem. Booting that PC to UBUNTU is perfectly fine. sudo lspci -vvv showed that it is a 2-lane PCIe gen3 storage device. Since it's inexpensive and only 2-lane PCIe, so I know it won't be a problem I cut the B-key slot (the third and fourth PCIe lanes are using some of these pins so I know it's not going to be a problem.) I cut the B-key slot and retried that NVMe SSD on that PC. It works fine. Nothing had changed. So the time is right to test it on my UDOO x86 Advanced (only has B-Key M.2 and thus only 2-lane PCIe available.) The result: - device is not detectable during boot time. <-- no surprise since I don't believe the current UDOO x86's BIOS has NVMe support - device is immediately detected after I booted the UDOO x86 thru other means. In my case, it's UBUNTU 16.04 LTS which has the built-in kernel driver for NVMe. See screenshot - that NVMe device size is 2280 so I have to improvise to fit it to UDOO x86 (only has 2260 mounting hole) Here I want to mention that there is no assurance a normal/common 4-lane PCIe NVMe will work the same way, i.e., intentionally de-rate/degrade it from 4-lane into 2-lane PCIe (by cutting the B-key slot) or it would even support 2-lane NVMe mode at all. ccs_hello
To make it clear to find a PCIe 2x NVMe SSD, you have to look into spec carefully. E.g., I bought this one (XPG SX6000 series) https://www.newegg.com/Product/Product.aspx?Item=0D9-0017-00070 I also found there are others, e.g., this Amazon item https://www.amazon.com/CORSAIR-FORCE-MP300-120GB-Storage/dp/B07D9C2WPV < -- this one comes with B+M key already in place. I.e., it has to be PCIe 2x (B-key does not support 4x)
