Default kernel options like root= or plymouth.enable are specific to the
kernel package (and initrd bundled with it). Start migrating away from
built-in defaults in core-admin by adding a file in kernel package
containing those options.
Also, if new enough initramfs is included, add xen_scrub_pages=0 which
will speed up the domain start.
QubesOS/qubes-issues#4839QubesOS/qubes-issues#4736