U-Boot is an alternative to the proprietary Rockchip loader binary
- u-boot documentation Note that rockchip u-boot is outdated and heavily modified.
- https://github.com/rkchrome/uboot A third part implemented rk u-boot with support for rk3288 only(Not update now)
The latest u-boot from rockchip would like to use the standard way to hold bootargs, they have dropper the parameter way. While the old rockchip u-boot always tries to read kernel arguments (bootargs) from the parameter partition from the configured boot medium. This may be surprising for booting from USB since your environment will likely get overriden unless you hack out this 'feature'. It is possible to pack bootargs into android kernel image which the rk bootloader ignores.