OpenWrt support for Xiaomi AX3000T

@alexq thank you very much for helping me.
I followed wiki, then I bricked it... then I founded your post on the forum and unbricked it with UART. Now I have problem to reproduce steps from wiki because when I do cat /proc/cmdline I get

console=ttyS0,115200n8 console_msg_format=syslog root=/dev/fit0 rootwait

when I try to detach mtd8 and try to install on that partitition I get:

ubiformat: error!: please, first detach mtd8 (/dev/mtd8) from ubi0
root@OpenWrt:~# ubidetach -p /dev/mtd8
ubidetach: error!: cannot detach "/dev/mtd8"
           error 16 (Resource busy)
root@OpenWrt:~#

when I try it on mtd9 I get:

root@OpenWrt:~# ubiformat /dev/mtd9 -y -f /tmp/openwrt-mediatek-filogic-xiaomi_mi-router-ax3000t-initramfs-factory.ubi
libmtd: error!: cannot get information about "/dev/mtd9"
        error 2 (No such file or directory)
ubiformat: error!: cannot get information about "/dev/mtd9"
           error 2 (No such file or directory)

my partitition table looks like this:

root@OpenWrt:~# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00100000 00020000 "BL2"
mtd1: 00040000 00020000 "Nvram"
mtd2: 00040000 00020000 "Bdata"
mtd3: 00200000 00020000 "Factory"
mtd4: 00200000 00020000 "FIP"
mtd5: 00040000 00020000 "crash"
mtd6: 00040000 00020000 "crash_log"
mtd7: 00040000 00020000 "KF"
mtd8: 07000000 00020000 "ubi"
root@OpenWrt:~#

and to answer to the other member I even switched uboot to openwrt u-boot because it is more clear for understanding....