Re: [Xen-devel] [PATCH 1/3] xen/privcmd: return -ENOSYS for unimplemented IOCTLs

[Boris Ostrovsky]

On 02/09/2017 09:40 AM, Jan Beulich wrote:
> > > > On 09.02.17 at 15:17, <paul.durrant@xxxxxxxxxx> wrote:
> > The code goes so far as to set the default return code to -ENOSYS but
> > then overrides this to -EINVAL in the switch() statement's default
> > case.
>
> If you already change this, isn't -ENOTTY the traditional way of
> indicating unsupported ioctls?

In fact, a while ago David submitted a patch to do just that:

https://lists.xenproject.org/archives/html/xen-devel/2016-08/msg00744.html

but it never went anywhere.

My question is whether anyone might be relying on current error return 
behavior.


-boris