L1 & L2 cache flush sequence on CortexA5 MPcore w.r.t low power modes

Antti P Miettinen ananaza at iki.fi
Sun Sep 23 17:32:06 EDT 2012

Antti P Miettinen <ananaza at iki.fi> writes:
> Hmm.. is the condition for cache coherence protocol then different from
> TLB lookups? If C is cleared, is the cache available for snoops by other
> cores? What happens if another core needs a dirty line in a cache that
> has C cleared?

Sorry - looks like you already answered this:
> 2) as long as they are taking part in coherency (SMP bit set in ACTLR), all
>    Cortex-A cores in a MP configuration with the SCTLR.C bit set can hit in
>    the cache of a CPU that runs with the C bit cleared in SCTLR

So other cores apparently can search the cache that has C bit
cleared. The only clarification I still would need is whether this
searching applies to also TLB fetches by other cores. So when you say:
> .. TLB fetches cannot search the D-cache if the C bit in
> SCTLR is clear on A9. ..

you meant TLB fethes by the core that has it's C bit cleared. The TLB
fetches by other cores will still search the cache just like any other
coherence searches?

Antti P Miettinen

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