Game consoles, and back in the day most MS-DOS, Amiga and Atari Games that only used hardware directly with OS services could in retrospective be considered some form of unikernels.

Amiga games used to be written such that they would boot the computer from floppy.

The Amiga had a large part of its regular OS libraries in ROM, and the base OS was available directly to the bootloader on the floppy.

You could ignore it and access the hardware directly, if you wanted, and many games did, but you could also use the OS if you wanted to.

The default bootloader would basically just say "launch the default shell and tell it to load the startup shell script file".

The MirageOS people at https://mirage.io/wiki/gallery have a list titled "unikernels that are used in production"

Most RTOSes.

z/TPF is also a unikernel so Visa when processing every transaction.

Interesting, do you have any references explaining how/why z/TPF is a unikernel? Thanks!

It's from an era before ubiquitous MMUs, even in IBM mainframes. It therefore was structured as a library OS, with even less separation between it and the application code than even MSDOS and it's applications.

Transaction Processing Facility: A Guide for Application Programmers by R. Jason Martin is a decent book I'd recommend on the subject.

Did not realise Visa was using z/TPF. Do you have a link with more information?

I don't know of much public information other than their job postings.

I believe Cisco had an unikernel running on Vmware for SDN vSwitches. Makes sense: you "only" need to move packets from some vLan to another vLan/vNic after applying policies... and you can forget about supporting hardware modules alien to you.

The automotive domain definitely use them (e.g., Open Synergy and others), since their efficiency means they consume fewer resources on ECUs, and their relatively small Trusted Computing Base (TCB) not only reduces exploits but also means certification is cheaper/faster.

Most devices are not web servers.