Oh wait, I see on the RK3588 CPU specs that the RK3588 actually has FIVE PCIe lanes: 4x PCIe v3 + 1x PCIe v2.
Somehow that 1x PCIe v2 is integrated with the USB 3.0 and the SATA, they call it “Combo PIPE PHY Interface”.
Does the M.2 M key on the bottom get the 4x PCIe v3, and the M.2 E key on the top get the 1x PCIe v2?
Oh wait a bit, reading the main Rock5 thread, I see a mentioning that there are more Rock5 variants and that one or both, use the “RK3588S” which is a limited RK3588 variant which only has 2x one PCIe v2 in total, is it?
Please clarify which Rock5 variants exist, and do they use RK3588S or RK3588?
(Cautionary note: There is also a “Rock5 Compute Module” and its specs are here https://wiki.radxa.com/Rock5/CM5 . That one is different altogether from the Rock5 SBC. Note that one is pin compatible with the Raspberry 4 Compute Module, and indeed it offers 2x PCIe v2 lanes.)