Re: [Xen-devel] [PATCH 03/17] xen/mm: Move the MM types in a separate header

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 26/03/2020 09:02, Jan Beulich wrote:
> On 25.03.2020 19:09, Julien Grall wrote:
> > Hi Jan,
> >
> > On 25/03/2020 15:00, Jan Beulich wrote:
> > > On 22.03.2020 17:14, julien@xxxxxxx wrote:
> > > > From: Julien Grall <jgrall@xxxxxxxxxx>
> > > >
> > > > It is getting incredibly difficult to use typesafe GFN/MFN/PFN in the
> > > > headers because of circular dependency. For instance, asm-x86/page.h
> > > > cannot include xen/mm.h.
> > > >
> > > > In order to convert more code to use typesafe, the types are now moved
> > > > in a separate header that requires only a few dependencies.
> > > We definitely need to do this, so thanks for investing the
> > > time. I think though that we want to settle up front (and
> > > perhaps record in a comment in the new header) what is or
> > > is not suitable to go into the new header. After all you're
> > > moving not just type definitions, but also simple helper
> > > functions.
> > I am expecting headers to use the typesafe helpers (such mfn_add)
> > in the long term. So I would like the new header to contain the
> > type definitions and any wrappers that would turn 'generic'
> > operations safe.
> >
> > I am not entirely sure yet how to formalize the rules in the
> > header. Any ideas?
> Well, if the header was just for the typesafe types, it could be
> renamed (to e.g. mm-typesafe.h) and be left without any respective
> comment. The issue I've mentioned arises if, with its currently
> suggested name, further types get added. In such a case perhaps it
> could be "type definitions and their immediate accessors,
> involving no other non-trivial types"?
I will rename the file to mm-typesafe.h.

Cheers,

--
Julien Grall