I downloaded and tested the new version released today (https://mirror.openshift.com/pub/openshift-v4/dependencies/rhcos/4.13/4.13.10/) for PXE install, the bootstrap machine is not booting as /sysroot cannot be mounted (Operation not permitted).

Previous version (4.13.5) was working with the same PXE scripts and machine setup (KVM).

Below you can find the boot log from serial and the usual PXE configuration.

4.13.10

Spin up a VM with initramfs, rootfs and kernel taken from the above link, it will result in an unbootable machine.

1. Download initramfs, rootfs, kernel images from https://mirror.openshift.com/pub/openshift-v4/dependencies/rhcos/4.13/4.13.10/

2. Configure PXE
3. Boot up a machine

The boot fails with mount[533]: mount: /sysroot: mount failed: Operation not permitted

The machine boots

Boot log: https://pastebin.com/Dnv0ZHk6

PXE Config:
[root@bastion ocpinstall]# cat /var/lib/tftpboot/pxelinux.cfg/01-52-54-00-62-78-8a                                        DEFAULT bootstrap                                                                                                           SAY Now booting the kernel from SYSLINUX...                                                                             LABEL bootstrap                                                                                                             KERNEL rhcos/rhcos-live-kernel-x86_64                                                                                     APPEND initrd=rhcos/rhcos-live-initramfs.x86_64.img coreos.live.rootfs_url=http://192.168.101.4/metal/rhcos-live-rootfs.x86_64.img coreos.inst.install_dev=/dev/vda coreos.inst.ignition_url=http://192.168.101.4/metal/bootstrap.ign  ip=ens3:dhcp ip=ens4:none console=tty0 console=ttyS0