Asus RT-AX1800U doesn't boot from USB

For Developers
1

Hi.
I want to boot from rootfs USB, I recompiled & flashed kernel to add support for ext4, usb3, usb storage and so on.
I tried
setenv bootargs=root/dev/sda1 console=ttyS0,115200
in u-boot but this do not work, what I'm doing wrong?
When kernel boots, there is my usb hdd sda1 recognized correctly, but still old
Kernel command line: console=ttyS0,115200
Currently the bootcmd=mtkautoboot, I think that I need to set this to nand read & bootm, but do not know correct adresses.
What I'm doing wrong?

2

root=/dev/sda1 would be my guess.

3

In most cases, the bootloader provided cmdline gets ignored by OpenWrt in favour of hardcoding it in the DTS.

4

Ok, so where are the DTS to modify root parameter?