Re: [Xen-devel] [PATCH v2 11/15] xen/arm: vgic-v2: Correctly handle RAZ/WI registers

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 02/02/15 17:41, Ian Campbell wrote:
> On Mon, 2015-02-02 at 17:08 +0000, Julien Grall wrote:
>> On 02/02/15 16:50, Ian Campbell wrote:
>>> On Mon, 2015-02-02 at 16:36 +0000, Julien Grall wrote:
>>>> Hi Ian,
>>>>
>>>> On 02/02/15 16:02, Ian Campbell wrote:
>>>>> On Thu, 2015-01-29 at 18:25 +0000, Julien Grall wrote:
>>>>>> Some of the registers are accessible via multiple size (see 
>>>>>> GICD_IPRIORITYR*).
>>>>>
>>>>> They are byte accessible, but are they half word accessible? I suspect
>>>>> not.
>>>>
>>>> Only byte accessible.
>>>
>>> I think we might need a read_as_zero_8_32 then, i.e. explicitly list the
>>> sizes which are allowed, and perhaps omit the un-suffixed version for so
>>> it's clear exactly what is what, although that might be more churn than
>>> you want to have here.
>>
>> Hmmm, why? I was talking for registers defined in the spec. We don't
>> know if reserved/implementation defined registers will allow half-word
>> access.
>>
>> The un-suffixed version is there when we don't need to check the size
>> because it has already been done. It seems pointless to check it again.
> 
> I'd forgotten the existing check was there, yes it does make sense to
> use it in this case.

Shall I clarify the commit message for this bit?

Regards,

-- 
Julien Grall

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