Re: [for-4.7 2/2] xen/arm: Document the behavior of XENMAPSPACE_dev_mmio

[Julien Grall <julien.grall@arm.com>]

Hi Jan,

On 25/05/16 14:14, Jan Beulich wrote:
>>>> On 25.05.16 at 13:41, <julien.grall@arm.com> wrote:
>> --- a/xen/include/public/memory.h
>> +++ b/xen/include/public/memory.h
>> @@ -220,7 +220,10 @@ DEFINE_XEN_GUEST_HANDLE(xen_machphys_mapping_t);
>>   #define XENMAPSPACE_gmfn_range   3 /* GMFN range, XENMEM_add_to_physmap only. */
>>   #define XENMAPSPACE_gmfn_foreign 4 /* GMFN from another dom,
>>                                       * XENMEM_add_to_physmap_batch only. */
>> -#define XENMAPSPACE_dev_mmio     5 /* device mmio region */
>> +#define XENMAPSPACE_dev_mmio     5 /* device mmio region
>> +                                      On ARM, the region will be mapped
>> +                                      in stage-2 using the memory attribute
>> +                                      Device_nGnRE. */
>
> Since this is unimplemented on x86, may I suggest to make this "ARM
> only; the region will be ..."?

Sounds good.

>
> Also - is Device_nGnRE a term uniform between ARM32 and ARM64?

Actually it should be Device-nGnRE to match with the spec. This has been 
introduced on Armv8. Previously for Armv7, the name was "Device", 
although the behavior is exactly the same.

I could say:

"ARM only; the region will be mapped in Stage-2 using the memory 
attribute 'Device-nGnRE' (previously named 'Device' on ARMv7)".

Regards,

-- 
Julien Grall

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