PowerPC Cache Warning Help Request

[Peter Dufault]

> On Oct 20, 2014, at 16:47 , Joel Sherrill <Joel.Sherrill at oarcorp.com> wrote:
> 
>> However, should unimplemented versions return an error instead of being
>> a NOP?  That would force one to visit code that makes assumptions.
> 
> If this is OK for the mpc55xx, feel free to submit a patch turning the warning off for it.
> 
> I tend to agree that if I had a generic drive that wanted to flush data cache and all we can do on a target is flush all, then that's preferable to flushing nothing.
> 
> If these are called from a cache test then we would end up with a hard error instead of a warning in that test which makes the issue worse. 
> 

I'm flat-out, I can't do a proper job on this.  I couldn't have told you that the MPC55XX had a unified cache before I checked this morning, but I would have gotten the answer correct on a multiple-choice question.

I think that unimplemented operations should return errors and not OK, forcing one to add an implementation when it is OK.  But the MPC55XX and its cache works fine as long as you keep cache-flushing in mind and flush it when you should, so I don't recommend anything be changed in the next RTEMS release.

Peter
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Peter Dufault
HD Associates, Inc.      Software and System Engineering