Warning

Make sure you run all commands as root, otherwise you might get a damaged rootfs image

Unpacking SquashFS from UBI volume

# ubireader_extract_images rootfs1.img
# cp ubifs-root/X/squashfs_ubi/img-X_vol-squashfs_ubi.ubifs .
# as root...
unsquashfs -d rootfs_extracted/ img-X_vol-squashfs_ubi.ubifs

Repacking SquashFS

rm -v new_squashfs.img
mksquashfs rootfs_extracted/ new_squashfs.img -comp xz -b 131072 -always-use-fragments -no-recovery -noappend

Repacking UBI volume

Firstly create ubinize.cfg with volume settings:

[squashfs_ubi]
mode=ubi
image=new_squashfs.img
vol_id=0
vol_type=static
vol_name=squashfs_ubi
vol_alignment=1

Re-build volume:

rm -v new_rootfs1.ubi
ubinize -o new_rootfs1.ubi -p 131072 -m 2048 -s 2048 ubinize.cfg

Writing to flash

Pay attention to what Image is active, inactive rootfs will be named rootfs1 inside /proc/mtd.

For safety only flash one slot at once to make recovery faster avoiding need for U-Boot Ymodem upload.

Documented modifications to rootfs

Enable WEB UI

On builds not ending with _eng file /sbin/httpd was deleted to disable WEBUI, copying it from _eng build will restore its function.

Disable TR-069

UCI configuration for TR-069 is saved inside /etc/config/easycwmp, deleteing ACS url will disable easycwmp process starting from its init script.

Installing full busybox

Precompiled busybox binary with all its features can be found here.

Place the full version into /bin/busybox-full or overlayfs and only create symlinks for tools you need.

Do not replace the old busybox binary, device uses mtd-utils version of ubi* commands and busybox implementation is incompatible if you replace them.