Fresh install does not detect /sbin/init

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https://bbs.archlinux.org – Even if all your partitions are btrfs subvolumes, you still have to tell the kernel/initramfs which partition to mount as your rootfs.  This is typically done with a kernel command line parameter.  So if your root is in fact the root of the btrfs filesystem, it would be rootflags=subvolid=0.  Though this can also be done by setting a default /.  Something like "btrfs subvolume set-default 0 /" would make that same subvolume the rootfs.  It should be that you can set defaults for every mountpoint, but I have not gotten this to work reliably, so I just put thin (HowTos)