how to switch from EL3 to El1 inside u-boot before linux kernel?

The screenshots is from linux enable_mmu section.

I only just want u-boot to execute the kernel image directly.But u-boot is at EL3,however linux is at EL1.

i want to know how u-boot to enter EL1 mode directly.

The screenshots is from linux enable_mmu section.

I only just want u-boot to execute the kernel image directly.But u-boot is at EL3,however linux is at EL1.

i want to know how u-boot to enter EL1 mode directly.