Is PCIE x4 bootable for NVMe SSD under Linux

[Bullet64]

Someone get it to work with mainline? For me only 4.4 is working.

Nope - I have 2 problems with 4.18 and so have reverted to 4.4.132 for the moment.

1. If I build an SDcard with 4.18 it boots fine if I have no eMMC nor NVMe plugged in. If I plug in the eMMC the boot hangs - it seems 4.18 cannot initialise eMMC ?
   
2. If I boot with just SDcard & NVMe 4.18 boots fine. If I move the 4.18 rootfs to /dev/nvme0n1 (as per your page) the boot hangs. I think it is because the PCI initialisation is very late in the standard 4.18 kernel and after the rootfs is mounted (comparing a boot from the SDcard to a boot from the NVMe.)
   

1:
will test it later today

2:
will rootwait=20 fix this?