Re: [Xen-devel] [PATCH 3/3] x86/HPET: cache MSI message last written

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.10.12 at 18:42, Keir Fraser <keir.xen@xxxxxxxxx> wrote:
> On 18/10/2012 11:39, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> 
>>>>> On 18.10.12 at 10:22, Keir Fraser <keir@xxxxxxx> wrote:
>>> On 16/10/2012 16:11, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
>>> 
>>>> Rather than spending measurable amounts of time reading back the most
>>>> recently written message, cache it in space previously unused, and thus
>>>> accelerate the CPU's entering of the intended C-state.
>>>> 
>>>> hpet_msi_read() ends up being unused after this change, but rather than
>>>> removing the function, it's being marked "unused" in order - that way
>>>> it can easily get used again should a new need for it arise.
>>> 
>>> Please use __attribute_used__
>> 
>> That wouldn't be correct: The function _is_ unused (and there's
>> no issue if it was used afaik), and the __used__ attribute ought
>> to tell the compiler to keep the function around despite not
>> having (visible to it) callers.
> 
> Perhaps our __attribute_used__ definition should change, then?

I don't think so - this has its own value as is. We may want to add
a Linux-like __maybe_unused, though.

Jan


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