Empty function at BaseCacheMaintenanceLib

Empty function at BaseCacheMaintenanceLib

[Rafael Machado]

Hi everyone

I have a question. During a research I got to the BaseCacheMaintenanceLib,
and noticed that there is a function that is not implemented.

The function InvalidateInstructionCache does not have a body, but as far as
I
could check it's used in some places.

Is it ok to have this function empty?

Thanks and Regards
Rafael R. Machado

Re: Empty function at BaseCacheMaintenanceLib

[Andrew Fish]

Rafael,

I seem to remember those functions are used to manage the cache on a Harvard architecture caches  [1].

If you look at InvalidateInstructionCacheRange() you will notice it is used when code gets loaded into memory to keep the data and instruction caches coherent. If the instruction cache maintains coherency in hardware then there is no need for this functions to do anything. 

If you notice the IPF version actually does something, and that is why these functions exists. 

[1]  https://en.wikipedia.org/wiki/Harvard_architecture <https://en.wikipedia.org/wiki/Harvard_architecture>

Thanks,

Andrew Fish

> On May 8, 2018, at 6:46 AM, Rafael Machado <rafaelrodrigues.machado@gmail.com> wrote:
> 
> Hi everyone
> 
> I have a question. During a research I got to the BaseCacheMaintenanceLib,
> and noticed that there is a function that is not implemented.
> 
> The function InvalidateInstructionCache does not have a body, but as far as
> I
> could check it's used in some places.
> 
> Is it ok to have this function empty?
> 
> Thanks and Regards
> Rafael R. Machado
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel

Re: Empty function at BaseCacheMaintenanceLib

[Rafael Machado]

Got it!

Thanks for the answer Andrew.

Rafael Machado

Em ter, 8 de mai de 2018 às 12:55, Andrew Fish <afish@apple.com> escreveu:

> Rafael,
>
> I seem to remember those functions are used to manage the cache on a
> Harvard architecture caches  [1].
>
> If you look at InvalidateInstructionCacheRange() you will notice it is
> used when code gets loaded into memory to keep the data and instruction
> caches coherent. If the instruction cache maintains coherency in hardware
> then there is no need for this functions to do anything.
>
> If you notice the IPF version actually does something, and that is why
> these functions exists.
>
> [1]  https://en.wikipedia.org/wiki/Harvard_architecture
>
> Thanks,
>
> Andrew Fish
>
> On May 8, 2018, at 6:46 AM, Rafael Machado <
> rafaelrodrigues.machado@gmail.com> wrote:
>
> Hi everyone
>
> I have a question. During a research I got to the BaseCacheMaintenanceLib,
> and noticed that there is a function that is not implemented.
>
> The function InvalidateInstructionCache does not have a body, but as far as
> I
> could check it's used in some places.
>
> Is it ok to have this function empty?
>
> Thanks and Regards
> Rafael R. Machado
>
> _______________________________________________
> edk2-devel mailing list
> edk2-devel@lists.01.org
> https://lists.01.org/mailman/listinfo/edk2-devel
>
>
>