Re: [Xen-devel] [PATCH RFC 25/35] arm: acpi add helper functions to map memory regions

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 5 Feb 2015, Julien Grall wrote:
> Hi parth,
> 
> Title: this is not acpi specific.
> 
> On 04/02/2015 14:02, parth.dixit@xxxxxxxxxx wrote:
> > From: Parth Dixit <parth.dixit@xxxxxxxxxx>
> > 
> > For passing ACPI tables to dom0, UEFI memory needs to be mapped
> > by xen in dom0 address space. This patch adds helper functions for mapping.
> 
> I believe that this is not ACPI/RAM specific. Any cached MMIO regions will
> have same issue.
> 
> This because Device memory is too strong and disallow unaligned access.
> 
> > Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/p2m.c        | 24 ++++++++++++++++++++++++
> >   xen/include/asm-arm/p2m.h | 10 ++++++++++
> >   2 files changed, 34 insertions(+)
> > 
> > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > index 8809f5a..5593a91 100644
> > --- a/xen/arch/arm/p2m.c
> > +++ b/xen/arch/arm/p2m.c
> > @@ -943,6 +943,30 @@ int p2m_populate_ram(struct domain *d,
> >                                0, MATTR_MEM, p2m_ram_rw);
> >   }
> > 
> > +int map_ram_regions(struct domain *d,
> > +                     unsigned long start_gfn,
> > +                     unsigned long nr,
> > +                     unsigned long mfn)
> 
> I don't like the name of the function. It gives the impression that we map any
> RAM region to the guest via this function.
> 
> Which is obviously wrong and should never be done.

map_mem_regions?

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