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CA9MP - Join and Leave coherency

Note: This was originally posted on 23rd July 2012 at http://forums.arm.com

Hi,

I have some thoughts regarding joining and disengaging cores to the coherency:
In the bootstrap, the case is very easy, the primary core enables the SCU and the secondary cores join to coherency by setting ACTLR.SMP after the L1 caches have been invalidated.
But, assume that one of the CA9 cores wish to leave the coherency.
What actions should be taken for doing it propely?
What happens to the data that was stored in that cache?


Thanks,
Shlomi


Parents
  • Note: This was originally posted on 24th July 2012 at http://forums.arm.com

    Hi,
    Thanks for replying.

    I'm wondering, what happens to the data in the D cache that just has been disabled. i.e. let's say that core X decides to leave the SMP and the data in its cache is dirty and used by  core Y for read. Will core Y get a stale data from L2/L3 memory? Perhaps, cache clean and invalidation should be broadcasted?

    Thanks,
    Shlomi
Reply
  • Note: This was originally posted on 24th July 2012 at http://forums.arm.com

    Hi,
    Thanks for replying.

    I'm wondering, what happens to the data in the D cache that just has been disabled. i.e. let's say that core X decides to leave the SMP and the data in its cache is dirty and used by  core Y for read. Will core Y get a stale data from L2/L3 memory? Perhaps, cache clean and invalidation should be broadcasted?

    Thanks,
    Shlomi
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