Since the version 0.6.58 there's a new extlinux helper code that replaces flash-kernel
making it possible to have completely device agnostic images,
as long as images do have SPI flash and u-boot loaded there (not yet, but in the future).
The new extlinux makes it easy to switch between all installed kernel versions.
The extlinux.conf is generated from contents of /boot and /etc/default/extlinux.
The configuration is automatically generated on the kernel installation.
You can edit /etc/default/extlinux to configure for example command line.
new_extlinux_boot.sh rootfsIt will make to boot device from / instead of /boot/efi that was used before.
new_extlinux_boot.sh flash-kernelupdate_extlinux.shThe result is stored in /boot/extlinux/extlinux.conf.