root 21:50:43 : ~ # rootfs.writable 
mounting rootfs writable
UBIFS: background thread "ubifs_bgt0_0" started, PID 978
root 21:50:46 : ~ # systemctl disable serial-getty@ttymxc4.service
rm '/etc/systemd/system/getty.target.wants/serial-getty@ttymxc4.service'
root 21:51:03 : ~ # find . -name \*serial\*service\*
root 21:51:20 : ~ # find / -name \*serial\*service\*
/etc/systemd/system/serial-getty@.service
/lib/systemd/system/serial-getty@.service
/run/systemd/generator/getty.target.wants/serial-getty@ttymxc4.service
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service/serial-getty@ttymxc4.service
/sys/fs/cgroup/systemd/system/serial-getty@.service
/sys/fs/cgroup/systemd/system/serial-getty@.service/serial-getty@ttymxc4.service
/var/dyn/backup_etc/systemd/system/serial-getty@.service
root 21:51:44 : ~ # rm /etc/systemd/system/serial-getty@.service 
root 21:51:54 : ~ # rm /lib/systemd/system/serial-getty@.service
</systemd/generator/getty.target.wants/serial-getty@ttymxc4.service          
root 21:52:08 : ~ # find / -name \*serial\*service\*             
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service/serial-getty@ttymxc4.service
/sys/fs/cgroup/systemd/system/serial-getty@.service
/sys/fs/cgroup/systemd/system/serial-getty@.service/serial-getty@ttymxc4.service
root 21:52:23 : ~ # find / -name \*serial\*service\*
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service
/sys/fs/cgroup/cpu,cpuacct/system/serial-getty@.service/serial-getty@ttymxc4.service
/sys/fs/cgroup/systemd/system/serial-getty@.service
/sys/fs/cgroup/systemd/system/serial-getty@.service/serial-getty@ttymxc4.service
find: /proc/222: No such file or directory