Hi Jan and Stefano
> -----Original Message-----
> From: Jan Beulich <[email protected]>
> Sent: Thursday, September 9, 2021 5:06 PM
> To: Penny Zheng <[email protected]>
> Cc: Bertrand Marquis <[email protected]>; Wei Chen
> <[email protected]>; [email protected];
> [email protected]; [email protected]
> Subject: Re: [PATCH v6 5/7] xen: re-define assign_pages and introduce a new
> function assign_page
>
> On 08.09.2021 11:52, Penny Zheng wrote:
> > In order to deal with the trouble of count-to-order conversion when
> > page number is not in a power-of-two, this commit re-define
> > assign_pages for nr pages and introduces a new helper assign_page for
> original page with a single order.
> >
> > Signed-off-by: Penny Zheng <[email protected]>
>
Stefano, Since I need to re-commit this one, I'll add-in your NIT suggestion in
commit 7("
xen/arm: introduce allocate_static_memory"), and push a new Serie asap. ;)
> I have to admit that I'm now very puzzled: Instead of restoring the long
> agreed
> upon ordering of parameters (and then keeping my A-b), you've dropped the
> ack.
>
> > --- a/xen/arch/x86/pv/dom0_build.c
> > +++ b/xen/arch/x86/pv/dom0_build.c
> > @@ -568,7 +568,7 @@ int __init dom0_construct_pv(struct domain *d,
> > else
> > {
> > while ( count-- )
> > - if ( assign_pages(d, mfn_to_page(_mfn(mfn++)), 0, 0) )
> > + if ( assign_pages(d, mfn_to_page(_mfn(mfn++)), 1, 0)
> > + )
>
> This change alone demonstrates the problem when it comes to backporting
> future changes: If the original patch contained a code addition similar to
> what
> you change to, without the person doing the backporting paying close
> attention, the result will be an order-1 request when an order-0 one is
> wanted.
> It was explained to you that in order to make people doing backports aware of
> this semantic change, the order of parameters of the function ought to be
> altered. That way the compiler will complain, and the person will know to look
> closely what adjustments are needed.
>
> In this context I find it further puzzling ...
>
> > --- a/xen/include/xen/mm.h
> > +++ b/xen/include/xen/mm.h
> > @@ -133,8 +133,14 @@ void heap_init_late(void);
> >
> > int assign_pages(
> > struct domain *d,
> > + struct page_info *pg,
> > + unsigned long nr,
> > + unsigned int memflags);
> > +
> > +int assign_page(
> > struct page_info *pg,
> > unsigned int order,
> > + struct domain *d,
> > unsigned int memflags);
>
> ... that you also neglected the request to harmonize the argument order of
> both functions. What we want (and what I thought has long been agreed
> upon) is e.g.
>
> int assign_pages(
> struct page_info *pg,
> unsigned long nr,
> struct domain *d,
> unsigned int memflags);
>
> int assign_page(
> struct page_info *pg,
> unsigned int order,
> struct domain *d,
> unsigned int memflags);
>
Sorry, my fault, I've wrongly interpretate julien's harmonize request twice.
> Jan
