extracting char devices: Failed to run synchronizer: Operation not supported

[alban]

I am using the git-master version: 6daefa8a008c3230495a76017eca546f6622bb1d

$ sudo /home/alban/bin/casync make --store=/home/alban/tmp/casync-test/store rootfs.caidx rootfs
b3af845d0620bab9b8e83d7f2380e740fe6e9ddc478ffed1622883808502c2e0
$ sudo /home/alban/bin/casync extract --store=/home/alban/tmp/casync-test/store ./rootfs.caidx rootfs2/
Failed to run synchronizer: Operation not supported

strace | grep EOPNOTSUPP gives 2 kinds of errors:

setxattr("/proc/self/fd/9", "system.posix_acl_access", "\2\0\0\0\1\0\7\0\377\377\377\377\4\0\7\0\377\377\377\377 \0\7\0\377\377\377\377", 28, 0) = -1 EOPNOTSUPP (Operation not supported)
ioctl(9, BTRFS_IOC_CLONE_RANGE or FICLONERANGE, {src_fd=11, src_offset=0, src_length=0, dest_offset=0}) = -1 EOPNOTSUPP (Operation not supported)

But the FICLONERANGE one was supposed to be fixed in https://github.com/systemd/casync/issues/20 so I don't know what it is...

The last lines with --verbose give:

Extracting dev
Extracting dev/agpgart
Extracted dev/agpgart
Failed to run synchronizer: Operation not supported

The rootfs directory was generated with:

$ docker2aci docker://ubuntu
$ sudo tar xf library-ubuntu-latest.aci
$ ls -l rootfs/dev/ | head
total 8
crw-rw----. 1 root      44 10, 175 Sep 15 11:53 agpgart
crw-rw----. 1 root rpcuser 14,   4 Sep 15 11:53 audio
crw-rw----. 1 root rpcuser 14,  20 Sep 15 11:53 audio1
crw-rw----. 1 root rpcuser 14,  36 Sep 15 11:53 audio2
crw-rw----. 1 root rpcuser 14,  52 Sep 15 11:53 audio3
crw-rw----. 1 root rpcuser 14,   7 Sep 15 11:53 audioctl
crw-------. 1 root tty      5,   1 Sep 15 11:53 console
lrwxrwxrwx. 1 root root         11 Sep 15 11:53 core -> /proc/kcore
crw-rw----. 1 root rpcuser 14,   3 Sep 15 11:53 dsp

Any idea how to debug this? Could this be a problem with character devices? The error message is not very explicit.

[kugel-]

I see this error with v2 as well as git as of e4a3c5e