Hi Yiping,
OK, Got it.
But one problem I encounter is "crng init done" very late in booting on OpenWrt-19.04 snapshot. and OpenWrt-19.07 is no problem for this. Pls help to check and solve this issue on your official release. Thanks in advance.
BusyBox v1.30.1 () built-in shell (ash)
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| - || _ | -__| || | | || _|| _|
|_______|| __|_____|__|__||________||__| |____|
|__| W I R E L E S S F R E E D O M
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OpenWrt SNAPSHOT, r9781-e0a1b878cd
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=== WARNING! =====================================
There is no root password defined on this device!
Use the "passwd" command to set up a new password
in order to prevent unauthorized SSH logins.
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root@OpenWrt:/# dmesg | grep crng
[ 0.000000] random: get_random_bytes called from start_kernel+0x80/0x420 with crng_init=0
root@OpenWrt:/# [ 258.865723] random: crng init done
BR
Paul