Re: [Xen-devel] [PATCH v1] xen/arm: Do not allocate pte entries for MAP_SMALL_PAGES

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2015-03-03 at 11:51 +0000, Julien Grall wrote:
> 
> On 03/03/2015 11:47, Ian Campbell wrote:
> >> I'm not sure to follow here. Do you think MAP_SMALL_PAGES should be
> >> defined as WRITE_ALLOC?
> >
> > Sorry I just meant that:
> >          +#define PAGE_HYPERVISOR_WC      ((DEV_WC) | PTE_PRESENT )
> > should be just:
> >          +#define PAGE_HYPERVISOR_WC      (DEV_WC | PTE_PRESENT )
> > etc, no need for the inner-()s.
> >
> > MAP_SMALL_PAGES was correct as
> >          +#define MAP_SMALL_PAGES         (WRITEALLOC)
> 
> I wanted to check the definition of MAP_SMALL_PAGES you were agreed.
> 
> I think using WRITEALLOC here is confusing. There is no resulting PTE 
> and therefore WRITEALLOC will never be set.
> 
> I think it would be better to have a separate helper (as you suggested 
> on a previous mail).

Ah yes, I'd forgotten I'd thought of that. A separate helper to
provision an empty PT range would indeed be the best thing here.


> 
> Regards,
> 



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