In the live install of Anaconda we use rsync to copy the install over to the target system. We bind mount /dev/ /proc/ /sys/ and a number of things under /dev/. When running rsync using -x (single file system) we get some errors:

17:48:50,259 INFO program: Running... rsync -pogAXtlHrDx /mnt/install/source/ /mnt/sysimage
17:48:51,536 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev"","security.selinux") failed: Permission denied (13)
17:48:51,538 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/fd"","security.selinux") failed: Permission denied (13)
17:48:51,538 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/full"","security.selinux") failed: Permission denied (13)
17:48:51,538 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/null"","security.selinux") failed: Permission denied (13)
17:48:51,539 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/ptmx"","security.selinux") failed: Permission denied (13)
17:48:51,539 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/random"","security.selinux") failed: Permission denied (13)
17:48:51,539 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/stderr"","security.selinux") failed: Permission denied (13)
17:48:51,540 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/stdin"","security.selinux") failed: Permission denied (13)
17:48:51,540 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/stdout"","security.selinux") failed: Permission denied (13)
17:48:51,540 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/tty"","security.selinux") failed: Permission denied (13)
17:48:51,541 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/urandom"","security.selinux") failed: Permission denied (13)
17:48:51,541 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/vcsa"","security.selinux") failed: Permission denied (13)
17:48:51,541 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/zero"","security.selinux") failed: Permission denied (13)
17:48:51,542 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/pts"","security.selinux") failed: Operation not supported (95)
17:48:51,542 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/dev/shm"","security.selinux") failed: Permission denied (13)
17:48:58,245 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/proc"","security.selinux") failed: Operation not supported (95)
17:48:58,249 ERR program: rsync: rsync_xal_set: lremovexattr(""/mnt/sysimage/sys"","security.selinux") failed: Operation not supported (95)
17:51:47,024 ERR program: rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1052) [sender=3.0.9]

Adding these directories as --excludes works, but isn't it an error that -x doesn't skip them?