I have a ls1021a-twr eva board. My linux kernel version is 4.19. I used lsdk1906
flex-builder -i mkrfs -r debian:lite:stretch
to generate the minimum size of the rootfs around 450 MB.
I also reduced the amount of modules from 460 to 98 in the system.
I still feel it takes quite large amount of time to boot the system. I wonder if any way knows a good way to decrease the amount of boost time.