After running: coreos-installer install -i /home/core/config.ign /dev/mmcblk0 and reboot, the node fail to start due to:
Failed to start Ignition OSTree: Mount (firstboot) /sysroot

Displaying logs from failed units: ignition-ostree-mount-firstboot-sysroot.service
ignition-ostree-mount-var.service
ignition-ostree-uuid-boot.service
rdma-load-modules@rdma.service
– Logs begin at Fri 2018-06-22 11:11:49 UTC, end at Fri 2018-06-22 11:12:37 UTC. –
Jun 22 11:12:18 systemd[1]: Starting Ignition OSTree: Mount (firstboot) /sysroot...
Jun 22 11:12:18 systemd[1]: ignition-ostree-mount-firstboot-sysroot.service: Main process exited, code=exited, status=32/n/a
Jun 22 11:12:18 systemd[1]: ignition-ostree-mount-firstboot-sysroot.service: Failed with result 'exit-code'.
Jun 22 11:12:18 systemd[1]: Failed to start Ignition OSTree: Mount (firstboot) /sysroot.
Jun 22 11:12:35 ignition-ostree-mount-sysroot[2952]: Mounting /dev/disk/by-label/root (/dev/mmcblk0p4) to /sysroot
Jun 22 11:12:35 ignition-ostree-mount-sysroot[2952]: mount: /sysroot: /dev/mmcblk0p4 already mounted on /sysroot/sysroot/sysroot.

I got emergency shell and this is what we have on the node:
:/# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mmcblk0 179:0 0 59.3G 0 disk

Seems to be related to: https://github.com/coreos/fedora-coreos-tracker/issues/735