Ext2fs doesn't have enough free space (it has only 1KB)
to store this primary loader, but we can put it into
an independent small 'boot' partition as NetBSD/hp300 does
if it's really necessary.
It could be a fun project to add smaller pre-primary loader
that loads ~8KB primary loader for ext2fs, but probably it's unlikely
because there is a functional wheel named GRUB for ext2fs.