Re: [ndctl PATCH v3 5/6] libcxl: add interfaces for SET_PARTITION_INFO mailbox command

[Alison Schofield <alison.schofield@intel.com>]

> > snip
> > >
> > >
> > > I don't understand what this is for?
> > >
> > > Let's back up. In order to future proof against spec changes, and
> > > endianness, struct packing and all other weird things that make struct
> > > ABIs hard to maintain compatibility the ndctl project adopts the
> > > libabc template of just not letting library consumers see any raw data
> > > structures or bit fields by default [1]. For a situation like this
> > > since the command only has one flag that affects the mode of operation
> > > I would just go ahead and define an enum for that explicitly.
> > >
> > > enum cxl_setpartition_mode {
> > >     CXL_SETPART_NONE,
> > >     CXL_SETPART_NEXTBOOT,
> > >     CXL_SETPART_IMMEDIATE,
> > > };
> > >
> > > Then the main function prototype becomes:
> > >
> > > int cxl_cmd_new_setpartition(struct cxl_memdev *memdev, unsigned long
> > > long volatile_capacity);
> > >
> > > ...with a new:
> > >
> > > int cxl_cmd_setpartition_set_mode(struct cxl_cmd *cmd, enum
> > > cxl_setpartition_mode mode);
> > >
> >
> > I don't understand setting of the mode separately. Can it be:
> >
> > int cxl_cmd_new_setpartition(struct cxl_memdev *memdev,
> >                              unsigned long long volatile_capacity,
> >                              enum cxl_setpartition_mode mode);
> 
> It could be, but what happens when the specification defines a new
> flag for this command? Then we would have cxl_cmd_new_setpartition()
> and cxl_cmd_new_setpartition2()  to add the new parameters. A helper
> function after establishing the cxl_cmd context lets you have
> flexibility to extend the base command by as many new flags and modes
> that come along... hopefully none, but you never know.

Got it. Doing the 'new' followed by 'mode' set up you suggested.
(Sorry, I didn't update this thread after our offline chat.)