Does OpenWrt's kernel support Access Control List?

The ACL utilities can be found at: https://openwrt.org/packages/pkgdata/acl

However, when I tried it did not work:

root@OpenWrt:~# setfacl -m u:my-user:rwx /mnt/samba/
setfacl: /mnt/samba/: Not supported

Does OpenWrt support ACL on the kernel side? I'm using 19.07.2.

Depends whether the respective kernel config flags are un/set

CONFIG_EXT4_FS_POSIX_ACL
CONFIG_REISERFS_FS_POSIX_ACL
CONFIG_JFS_POSIX_ACL
CONFIG_XFS_POSIX_ACL
CONFIG_BTRFS_FS_POSIX_ACL
CONFIG_F2FS_FS_POSIX_ACL
CONFIG_FS_POSIX_ACL
CONFIG_TMPFS_POSIX_ACL
CONFIG_JFFS2_FS_POSIX_ACL
CONFIG_NFS_V3_ACL
CONFIG_NFSD_V3_ACL
CONFIG_CIFS_ACL

Is there anyway to check that on my current system? And do I need to build OpenWrt from source if it is not supported by the prebuilt image?