NixOS on ARM/ODROID-C2

I used minicom to access the serial:

$ cat /etc/minirc.odroid-c2 
# Machine-generated file - use "minicom -s" to change parameters.
pu port             /dev/ttyUSB0
pu lock             /var/lock
pu rtscts           No

then run `sudo minicom` to access the serial console.

To provision the system and set it up for netboot:

1. reboot

2. press enter right after boot, where it says:

Hit [Enter] key twice to stop autoboot:  0

3. run:

setenv gatewayip 10.5.3.1
setenv ipaddr 10.5.3.11
setenv serverip 10.5.3.1
setenv bootcmd "tftpboot"
savenv

then rebooted