I have busybox with an initramfs. When I try to re-mount the rootfs I
see this. This is with Yocto. Do I need to include systemd in my
initramfs image?

sh-5.0# exec switch_root /root /sbin/init
switch_root: failed to mount moving /run to /root/run: Invalid argument
switch_root: forcing unmount of /run
[ 339.929584] systemd[1]: System time before build time, advancing clock.
[ 339.974784] systemd[1]: Module 'autofs4' is built in
[ 339.980811] systemd[1]: Failed to mount tmpfs at /sys/fs/cgroup: No such file
or directory
[ 339.989411] systemd[1]: Failed to mount cgroup at /sys/fs/cgroup/systemd: No
such file or directory
[!!!!!!] Failed to mount API filesystems.
[ 340.024657] systemd[1]: Freezing execution.