It's interesting how tcp/ip is pretty much taken for granted. Of course you could run SLIP over that serial port ;)
Just the other day I was bitching about how it is easier to drive a printer than a relay from a present day computer, the answer I got back was 'can't you use an arduino?'...
Hehe you'd be /amazed/ how much smaller the kernel gets it you don't put in IPv4/6 -- and let me tell you, when you upload via uart, every little helps :-)
My fav method is to build a kernel with just busybox using my minifs [0], making sure I have kexec support in that kernel.
Once booted, I can upload a new kernel via zmodem, and kexec straight into the new kernel. Rince, repeat!
You can also use zmodem to upload new binaries to a system, even if it's an initramfs, without having to do a full rebuild/reboot. Quite handy.
Just the other day I was bitching about how it is easier to drive a printer than a relay from a present day computer, the answer I got back was 'can't you use an arduino?'...