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I am trying to enable xattrs and acls on a Debian machine. I've (re)mounted the partition in question with user_xattr and acl. (/dev/md3 is the partition in question)

root@fs01:/# mount | grep /dev/md
/dev/md0 on / type ext3 (rw,noatime,nodiratime,barrier=1,user_xattr,acl)
/dev/md3 on /DataVolume type ext4 (rw,noatime,nodiratime,acl,user_xattr)

And the ACL tools are installed.

root@fs01:/# dpkg-query -W -f='${Status} ${Version}\n' acl
install ok installed 2.2.49-4
root@fs01:/# dpkg-query -W -f='${Status} ${Version}\n' libacl1
install ok installed 2.2.49-4

Xattrs worked out of the box; ACLs didn't. Getfacl works without error:

root@fs01:/# getfacl /DataVolume/hi
# file: /DataVolume/hi
# owner: root
# group: root
user::rw-
group::rw-
other::rw-

because it is only returning the native *nix permissions; there aren't any ACLs because I can't set them:

root@fs01:/# setfacl -m u:root:rwx /DataVolume/hi
setfacl: /DataVolume/hi: Operation not supported

I'm assuming that it's disabled in the kernel, but I can't find any way to check it; kernel config file/source isn't provided for this particular build... (Packaged for an embedded system, unnecessary files were stripped out to minimize footprint) But if it was disabled in the kernel, I wouldn't be able to mount the partition with the acl flag, correct? Any help is appreciated!

(Originally posted on superuser.com - moved here after no interest.)

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    Your kernel config may be available in /proc/config.gz if one isn't stored in /boot. – HBruijn Jul 15 '14 at 19:09
  • Unfortunately not; it boots from a uBoot image, so no config in /boot. There isn't one in /proc either, though I'm not entirely sure why. Likely the same reason... – Chris Jul 16 '14 at 0:39
  • 1
    I'm fairly certain you can mount the filesystem with the acl option even if the kernel lacks ACL support. I haven't checked, but I think the kernel will verify at mount time whether the options you specified are valid for the filesystem type (and "acl" is a valid option for ext4); this is orthogonal to the behaviour of setfacl, which will just return an error if the kernel support isn't there. – András Korn Sep 1 '14 at 14:46

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