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> ...and are not affected by speculative execution AMD's chips definitely speculatively execute instructions. It's a common performance trick. AMD's chips al
by coherentpony 8y ago
> ...and are not affected by speculative execution
AMD's chips definitely speculatively execute instructions. It's a common performance trick.
AMD's chips also definitely throw an exception at retirement (of course) for instructions that attempt to load a privileged address, just like Intel's chips do.
The difference is that when AMD's chips see a load instruction, the load isn't executed until it knows that the address isn't privileged. Intel's chips do execute the load (but then throw away the result when it realises the address was privileged).
The speculative part is for instructions that depend on the result of the load.
- simion314 8y ago>The difference is that when AMD's chips see a load instruction, the load isn't executed until it knows that the address isn't privileged. Intel's chips do execute the load (but then throw away the result when it realises the address was privileged) Thank you for the detailed explanation, can't we conclude that AMD engineering is more defensive then Intel, this is what I concluded.
- coherentpony 8y agoBased on this datapoint? I don't think so. They're vulnerable to other side-channel attacks. Both AMD and Intel hire really smart people, but this stuff is really, really hard.
- Symmetry 8y agoThe general reaction from CPU designers I interact with online after this was that Intel engineers should have known the optimizations that enabled Meltdown were dangerous but that Specter was totally unforeseeable.
- deleted 8y ago[deleted]