The options I can get from the information found are the following (please add any corrections or suggestions):
1) iPXE + terminal console: PXE alone can't get nfsroot settings dynamically. PXE + iPXE should be added to the chain and LAVA should have access to terminal console.
2) iPXE + environment variables: LAVA sets environment variables and PXE + iPXE gets nfsroot settings from environment variables. No terminal console needed.
3) PXE + static folder: LAVA fetches and extract rootfs always to the same folder. PXE
reads static configuration file.
4) PXE + dynamic folder: LAVA sets the
nfsroot folder name directly on the PXE configuration file (file is machine specific).
5)
PXE + INITRAMFS: fetches root file system from file server
and extracts to memory.