Re: [Xen-devel] [PATCH v8 for-4.12 10/17] argo: implement the notify op

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.02.19 at 10:15, <persaur@xxxxxxxxx> wrote:
> On Feb 7, 2019, at 04:04, Julien Grall <julien.grall@xxxxxxx> wrote:
>>> On 2/7/19 6:32 AM, Christopher Clark wrote:
>>> It uses that null test because both are XEN_GUEST_HANDLE_PARAM type in
>>> the function signature:
>>> long do_argo_op(
>>>     unsigned int cmd,
>>>     XEN_GUEST_HANDLE_PARAM(void) arg1,
>>>     XEN_GUEST_HANDLE_PARAM(void) arg2,
>>>     unsigned long arg3,
>>>     unsigned long arg4);
>>> and since it does that, the comment states NULL rather than zero.
>>> It is Xen's definition for NULL that is used, so the expected value in
>>> the register when the hypercall is invoked is: zero.
>> 
>> As above, I don't think it is clearly define in the headers that NULL means 
> 0. This is rather an implicit written rules in the hope that every OS are 
> going to follow that.
>> 
>> I know, I am pedantic here (hence the NIT) :). And I realize this is not 
> related to this series and a few places in the code assumes the same.
>> 
>>>>> + * arg3: 0 (ZERO)
>>>>> + * arg4: 0 (ZERO)
>>>> 
>>>> NIT: I guess those to will be 0 in an unsigned long value?
>>> Yes.
>> 
>> Can this be clarified in a follow-up patch?
> 
> Since this is a comment revision, could it be made by the committer during 
> the imminent merge of this Argo series?

I'm not going to alter the comments, as I don't really see what is in need
of clarification here. If any clarification is indeed needed, this will need to
happen in follow-on patches.

Jan



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