Re: [PATCH v3 01/18] nitro_enclaves: Add ioctl interface definition

[Paraschiv, Andra-Irina]

On 05/06/2020 11:15, Stefan Hajnoczi wrote:
> On Mon, Jun 01, 2020 at 10:20:18AM +0300, Paraschiv, Andra-Irina wrote:
> > On 01/06/2020 06:02, Benjamin Herrenschmidt wrote:
> > > On Wed, 2020-05-27 at 09:49 +0100, Stefan Hajnoczi wrote:
> > > > What about feature bits or a API version number field? If you add
> > > > features to the NE driver, how will userspace detect them?
> > > >
> > > > Even if you intend to always compile userspace against the exact kernel
> > > > headers that the program will run on, it can still be useful to have an
> > > > API version for informational purposes and to easily prevent user
> > > > errors (running a new userspace binary on an old kernel where the API is
> > > > different).
> > > >
> > > > Finally, reserved struct fields may come in handy in the future. That
> > > > way userspace and the kernel don't need to explicitly handle multiple
> > > > struct sizes.
> > > Beware, Greg might disagree :)
> > >
> > > That said, yes, at least a way to query the API version would be
> > > useful.
> > I see there are several thoughts with regard to extensions possibilities. :)
> >
> > I added an ioctl for getting the API version, we have now a way to query
> > that info. Also, I updated the sample in this patch series to check for the
> > API version.
> Great. The ideas are orthogonal and not all of them need to be used
> together. As long as their is a way of extending the API cleanly in the
> future then extensions can be made without breaking userspace.

Agree, as we achieve the ultimate goal of having a stable interface, 
open for extensions without breaking changes.

Thanks,
Andra



Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.