Re: [PATCH] libnvdimm: clean up command definitions

[Dan Williams]

On Mon, Aug 28, 2017 at 1:50 PM, Jerry Hoemann <jerry.hoemann@xxxxxxx> wrote:
>
> On Mon, Aug 28, 2017 at 08:45:32AM -0700, Dan Williams wrote:
>> Remove the command payloads that do not have an associated libnvdimm
>> ioctl. I.e. remove the payloads that would only ever be carried in the
>> ND_CMD_CALL envelope. This prevents userspace from growing unnecessary
>> dependencies on this kernel header when userspace already has everything
>> it needs to craft and send these commands.
>
> Userspace needs to include linux/ndctl.h to make the call as
> that is where nd_cmd_pkg is defined.
>
> So you want to have some structures defined in ndctl.h and other
> defined in the to be created libndctl-nfit.h?  Plus a third header
> file for the HPE non-root calls?

Yes. ndctl.h exports the ioctl command payloads, everything that goes
inside of ND_CMD_CALL is defined by userspace headers. The
libndctl-nfit.h header is proposed as a place to land vendor agnostic
NFIT-defined payloads, and any vendor specific definitions would
remain internal to libndctl as they are today.

> Will libndctl-nfit.h be generally available and installed?

Yes, that's the plan.

> Will it be clean so that other applications can use it to get these
> definitions?  Or will it be loaded w/ a bunch of stuff only useful
> to your ndctl command?

Yes, that's the plan. It's a bug if libndctl-nfit.h is not generically
clean for issuing the NFIT root device commands via some ND_CMD_CALL
helpers from the base libndctl library.

In other words libndctl-nfit.h defines the payload and libndctl
defines some general helpers for issuing commands.