Bootloader pager?

So the bootloader seems to have no pager for the help. Sigh. So … if I have a bootable NVMe board and a bootable USB stick, it seems to favour the NVMe board. How do I direct it to boot from one or other from the console?

My goal here is to test installers — so, generally, the NVMe is going to be previously installed … unless, that is, I remove it and blank it each time.

run bootcmd_mmc0
run bootcmd_nvme0
etc

This is documented in the SW Reference Manual available from https://www.sifive.com/boards/hifive-unmatched
in section 2.7 Boot Options including NVMe.

The SiFive u-boot looks for the extlinux.conf file, so I think you can stop it from booting from a device if you rename this file, but I haven’t tried this myself.