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Atom CPUs were in-order execution, at least at first, AFAIK. So, without speculation and an OOE engine, Meltdown and Spectre can't happen.
by SomeHacker44 9y ago
Atom CPUs were in-order execution, at least at first, AFAIK. So, without speculation and an OOE engine, Meltdown and Spectre can't happen.
- phire 9y agoJust because the execution is in-order, doesn't mean there is no speculative execution. The 360 cpu (and the closely related ps3 cpu) is the perfect example of this. Despite the fact that it's 100% in-order, it has a very long instruction pipeline (upto 50 instructions long) and branch prediction. And that's all Spectre needs, a long pipeline + branch prediction. I'm not even 100% sure the intel atom will be safe from Spectre & Meltdown. It's pipeline is much shorter, only 16 stages long, but it still speculatively executes up-to 32 instructions (2 instructions per cycle). It just makes things harder, you have to find a Spectre gadget that's short enough. Though piss-easy for Meltdown, because you can just hand-assemble short code.