VZ backups with ACL and XATTR support, best way?

Hi all!

I have a container running Samba 4 that needs ACL and XATTR support. The container is stored on a EXT4 partition mounted in fstab with "user_xattr,acl" options, and all works perfectly.

Now, I want to create backups for this container saving those extended attributes. I have downloaded GNU TAR source code and I compiled with ACL and XATTR support. The problem is Proxmox backups is still not storing this extended information. So my question is, what is the best way to add ACL and XATTR support to Proxmox backups? Is there any official procedure?

Thanks in advance!

Best regards,
Ander.