Compatibility with Rock 4B+

[eldondevat]

Hi! According to what I can find, the Rock 4B+ is an RK3399 platform with an m.2 M-key pci-e port which can be had very cheaply here.

I tried to check the pinouts against the Rock 5B here and the only difference I could see were pins 44 and 46, CLK_3P and CLK_3N.

I would like to consider using two of these riser cards along with one of these (20cm, R22NS(Tx to Rx)) cables .

My goal is to potentially replicate your eNVMe work (for less than $100, perhaps?), and to consider what it would look like to implement other endpoint functions. I know in you also mentioned having an interest in one of the SQRL/Fury FPGA boards, I may be able to get you one, I believe I picked some up when they were being liquidated on ebay. I may be headed back to EU from the US for vacation this winter, or try to chaospost it.

If you could give your perspective on whether this setup can be successful, that would be great!

[rick-heig]

Hello,
If your goal is to replicate the eNVMe work for the Rock 4B+, that seems totally doable but requires some know-how.

I'll give you some answers and pointers

• For the clock pins I don't think that matters, also if I recall correctly it is possible to run the PCIe controllers in separate clock mode, where the PCIe clock comes from an internal source, so you don't even need the clock in the cables.
• For the risers, you can also use cheap USB 3.0 to PCIe x1 adapters/risers. But the other adapter seems fine as well.
• I would start setting up regular NVMe based on this buildroot : https://github.com/damien-lemoal/buildroot/tree/rockpro64_ep_v31 and adapt the defconfig https://github.com/damien-lemoal/buildroot/blob/rockpro64_ep_v31/configs/rockpro64_ep_defconfig (copy for Rock4b and edit) and board config https://github.com/damien-lemoal/buildroot/tree/rockpro64_ep_v31/board/pine64/rockpro64_ep (copy to a Rock4b directory and adapt) The Rock4b has a device tree in mainline linux see https://elixir.bootlin.com/linux/v6.17/source/arch/arm64/boot/dts/rockchip so it should not be a problem. You'll need to prepare a patch for it similarly as https://github.com/damien-lemoal/buildroot/blob/rockpro64_ep_v31/board/pine64/rockpro64_ep/uboot_patches/0001-board-rockpro64-Enable-PCIe-endpoint-mode.patch
• Once you can build, prepare the SD, and test the regular NVMe (the scripts will be in /root/pci-ep, they have a help message) you'll be ready to go eNVMe and you can follow the instructions from step 2 here https://github.com/rick-heig/eNVMe/blob/main/doc/platform.md

I think creating the buildroot setup from the RockPro64 (also RK3399 based) to the Rock 4B+ should not be too difficult, although it requires quite a few edits and it is easy to miss something, once you've done this you can already play around with NVMe functionality. Then moving to eNVMe is just time consuming, but all instructions are there, and you already tested functionality with the base NVMe driver.

Also you'll probably need an UART to USB adapter as the Linux built by buildroot doesn't have graphical output.

I Thank you very much for proposing the SQRL board.
I'd be happy to get one, but as I recently changed jobs, I have very little time to dedicate to this project.

I hope you'll get success with setting up your board, it is the same SoC than the RockPro64 so there is not reason it wouldn't work, it is just a matter of adapting the build. Then when you have regular NVMe, you can go to eNVMe (which you can build out of tree and just install as a module, then you can add the fun stuff like PCILeech).

Best regards,
Rick