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Re: Arch qualification for buster: call for DSA, Security, toolchain concerns

On Fri, Jun 29, 2018 at 06:29:48PM +0200, Geert Uytterhoeven wrote:
> Are you sure you're not interchanging A8 and A9, cfr. Linux kernel commit
> e388b80288aade31 ("ARM: spectre-v2: add Cortex A8 and A15 validation of the
> IBE bit")?

Yes.  That is the main reason the A9 is faster than the A8 at the same
clock speed by quite a bit.

For example http://www.360doc.com/content/12/0806/14/350555_228637047.shtml says:
Cortex-A9 has many advanced features for a RISC CPU, such as speculative
data accesses, branch prediction, multi-issuing of instructions,
hardware cache coherency, out-of-order execution and register renaming.
Cortex-A8 does not have these, except for dual-issuing instructions and
branch prediction.

So the A8 still has branch prediction so it can keep the pipeline fed,
even with in order execution.  Spectre isn't really about out-of-order
excution as much as it is about speculative memory accesses which some
in-order execution chips have too.

Len Sorensen

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