U-boot stop

I try to stop U-boot to use UMS so I press a key to stop autoboot but can’t
When 3399 loaded I can input commands from console.
So how to stop u-boot?

check our wiki:
http://wiki.t-firefly.com/index.php/Firefly-RK3399/Uboot/en

#define CONFIG_BOOTDELAY 1

So I need recompile u-boot?

yes ,you need .

yes ,you need .