M.2 SSD setting

We are testing different M.2 SSD on AGX and found a 4 lane SSD worked on AGX.
Our question is how to setup ‘num-lanes’ of ‘pcie@14180000’?

From the link below, used a 4 lane M.2 SSD on Agx, the ‘num-lanes’ of ‘pcie@14180000’ is supposed to set to 4.
The thing is the ‘num-lanes’ of ‘pcie@14180000’ is 8 in R31.1 by default, and a 4 lane SSD works.

It’s confused and we don’t know how to set it correctly.

https://devtalk.nvidia.com/default/topic/1055466/jetson-agx-xavier/i-has-customer-report-that-agx-xavier-dvk-cannot-find-two-different-vendors-m-2-key-m-ssd-on-internal-m-2-slot-j1-but-can-found-on-a-pcie-slot-j6-with-adapter-/ #11

Thank you for any advice.

Well, Ideally you don’t need to update ‘num-lanes’ as an x8 controller can work with an x4 and x2 cards without any issues.
Having said that, we did encounter Realtek NVMe controller-based NVMe cards which advertise x2 capability and they seem to have issues with Jetson-Xavier boards and the solution for that is to update ‘num-lanes’ to ‘2’.
Bottom line is, edit ‘num-lanes’ only if something doesn’t work.

Hi vidyas,

Thank you for your explanation.
We will explain to our customer.


Due to some M.2 SSD do not work on Agx Javier with agx released SDK.
Is there any criteria and/or compatibility listing for the devices which work on Xavier?

Thank you,

Well, as I mentioned, all M.2 SSDs have been working till we found the issue with SSD based on Realtek NVMe controller which is a x2 capable controller (from the config space) but looks wise it appears to be a x4 card.
So, this is the only card/controller for which an edit in ‘num-lanes’ property is required. Otherwise, all M.2 SSDs should work without any issue.

Hi vidyas,

Thank you for your explanation.