Re: [Xen-devel] [PATCH v2 13/24] xen/arm: page: Remove unused attributes DEV_NONSHARED and DEV_CACHED

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 20/09/17 00:32, Stefano Stabellini wrote:
> On Tue, 12 Sep 2017, Julien Grall wrote:
> > They were imported from non-LPAE Linux, but Xen is LPAE only. It is time
> > to do some clean-up in the memory attribute and keep only what make
> > sense for Xen. Follow-up patch will do more clean-up.
> >
> > Also, update the comment saying our attribute matches Linux.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> > Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
> >
> > ---
> >      Changes in v2:
> >          - Add Andre's reviewed-by
> > ---
> >   xen/include/asm-arm/page.h | 10 +++-------
> >   1 file changed, 3 insertions(+), 7 deletions(-)
> >
> > diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> > index b8d641bfaf..d7939bb944 100644
> > --- a/xen/include/asm-arm/page.h
> > +++ b/xen/include/asm-arm/page.h
> > @@ -21,9 +21,9 @@
> >   #define LPAE_SH_OUTER         0x2
> >   #define LPAE_SH_INNER         0x3
> >   
> > -/* LPAE Memory region attributes, to match Linux's (non-LPAE) choices.
> > - * Indexed by the AttrIndex bits of a LPAE entry;
> > - * the 8-bit fields are packed little-endian into MAIR0 and MAIR1
> > +/*
> > + * LPAE Memory region attributes. Indexed by the AttrIndex bits of a
> > + * LPAE entry; the 8-bit fields are packed little-endian into MAIR0 and MAIR1.
> >    *
> >    *                 ai    encoding
> >    *   UNCACHED      000   0000 0000  -- Strongly Ordered
> > @@ -35,9 +35,7 @@
> >    *   reserved      110
> >    *   WRITEALLOC    111   1111 1111  -- Write-back write-allocate
> >    *
> > - *   DEV_NONSHARED 100   (== DEV_SHARED)
> >    *   DEV_WC        001   (== BUFFERABLE)
> > - *   DEV_CACHED    011   (== WRITEBACK)
> >    */
> >   #define MAIR0VAL 0xeeaa4400
> >   #define MAIR1VAL 0xff000004
> I am OK with removing unused memory attributes, but please update
> MAIR0VAL and MAIR1VAL accordingly.  They still have their old values
> here.
As you may have seen below in the patch. They were just aliased to other 
attributes:
#define DEV_NONSHARED DEV_SHARED
#define DEV_CACHED    WRITEBACK

I removed them because they are unused and just wrongly named.

So there are no need to update MAIR0VAL and MAIR1VAL.

Cheers,

--
Julien Grall

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