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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

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.


> @@ -57,9 +55,7 @@
>  #define WRITEBACK     0x3
>  #define DEV_SHARED    0x4
>  #define WRITEALLOC    0x7
> -#define DEV_NONSHARED DEV_SHARED
>  #define DEV_WC        BUFFERABLE
> -#define DEV_CACHED    WRITEBACK
>  
>  #define PAGE_HYPERVISOR         (WRITEALLOC)
>  #define PAGE_HYPERVISOR_NOCACHE (DEV_SHARED)
> -- 
> 2.11.0
> 

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