Working on Ubuntu 16.04 LTS x64 edition.
Use https://github.com/richfelker/musl-cross-make to create an i486 musl cross compiler
Use https://github.com/landley/mkroot to create a kernel + file system image
Copied mkroot/modules/kernel to mkroot/modules/kernel-ab and removed some of the config options: -ipv6 support -ethernet -ethernet card driver -ext2/4 and vfat support -high performance timer -no hz mode -
The final kernel + compressed ram image is ~1500kb. It includes a 16550 serial driver for the console, and we have a 16550 serial port on the V3 MS-DOS Support Board.
Booting this image in QEMU requires 24 MB of RAM.
We will need to support the 'Query System Memory Map' function - http://www.uruk.org/orig-grub/mem64mb.html - for the kernel to know what memory is in the system.