3aea2923e9
Userspace part of reroot support. This makes it possible to change the root filesystem without full reboot, using "reboot -r". This can be used to to eg. boot from a temporary md_image preloaded by loader(8), setup an iSCSI session, and continue booting from rootfs mounted over iSCSI. Relnotes: yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D3693