On Thu, 04 Feb 2010, Bodo Eggert wrote:Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
Additionally, return -EINVAL if an unknown flag is encountered. This
makes it possible for the caller to determine if a flag is supported
or not (at least on kernels with this patch).
There should be a guaranteed-to-be-invalid flag or flag-combination in
order to safely detect this feature.
It's difficult though, because the app would have to make sure the
detection itself would reliably fail, and with a different error.
Simply checking the kernel version might be easier.