Hey Peter, I really do need more serial ports. Two, actually. I'm using qemu on build.wireguard.com for CI. I have normal output come on ttyS0 (ttyAMA0) and then if it's successful, the final step is writing "success" into ttyS1 (ttyAMA1), so that I can confirm with certainty that the tests succeeded. In other words, one channel for text output and one channel for control messages. (And I really really don't want to use virtio or PCI-based stuff for this.)
So I'm extending the CI on build.wireguard.com now to support ARM and MIPS, and things are not very smooth in the ARM world. Jason