Re: [RFC] MIPS: Add cacheinfo support

[Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>]

On 12/13/2016 03:09 AM, Maciej W. Rozycki wrote:
> On Tue, 13 Dec 2016, Leonid Yegoshin wrote:
>
>> Well, I prefer the collection of 3 flags:
>>
>> flush_required        - or flush to next level is required to force coherency
>> between this level and next after update of this level
>> invalidate_required   - or invalidate is required to force coherency between
>> this level and next after update of next level
>> coherent_to_level     - object is coherent with this level (only one domain of
>> coherency on this level is assumed)
>   A "flush" has always been an ambiguous term -- meaning anything from
> "write-back", through "write-back+invalidate" to "invalidate".  What is
> "flush" is supposed to exactly mean here?  If specifically any of the two
> formers (the latter is obviously the other flag), then I suggest using the
> respective name, or otherwise if it is meant to be generic "do what is
> needed", then perhaps "synchronize" will work, like with the name of the
> SYNCI instruction?
>
Well, I am not expert in choosing names, you know. I just would like to 
make a distinguishing between "transfer data from this level to next 
one" - any way - writeback or write-back-invalidate, and "clear data in 
this level to be pulled on demand from next level".

This is an information purpose as Florian described, so details can be 
skipped. The only useful info here - some efforts are needed after event 
(see above) and that efforts are not cheap from performance point of view.

If we put here details then it is a long way because we need a lot of 
details, see my original post. However, I would like to differ "flush" 
and "invalidate" because it is triggered by different kind of event 
(from upstream or from downstream).

- Leonid.