Unlock U-boot

Hardware Arduino Yún
1

Hi,

I want to change the u-boot in Linino Enviroment. how can i unlock it?

in general OpenWrt, i can unlock by changing:
target/linux/ar71xx/files/drivers/mtd/tplinkpart.c)static struct mtd_partition tl_wr1043nd_partitions[] = {
{
.name = "u-boot",
.offset = 0,
.size = 0x020000,
.mask_flags = MTD_WRITEABLE, -->> comment this link.
}

but it doesn't work for Linino. The art is by default unlock btw.

root@Arduino:~# mtd unlock u-boot
Could not open mtd device: u-boot
Could not open mtd device: u-boot
root@Arduino:~# mtd unlock art
Unlocking art ...
root@Arduino:~#