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Comment by lomnakkus

8 years ago

I believe it may be because the email only mentioned Intel explicitly and had a "I won't be buying Intel in future" (paraphrased) comment. However, I personally wouldn't assume that AMDs HT implementation doesn't have similar issues.

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lomnakkus

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Tuna-Fish  8 years ago

> However, I personally wouldn't assume that AMDs HT implementation doesn't have similar issues.

It does not. The fundamental difference between AMD and Intel CPUs in all these faults is that AMD does all permissions checks eagerly before returning results from memory, while when speculating, Intel defers them until speculation is resolved.

This does not mean that AMD escaped all of it, because some of the attacks (eg, spectre variant 1) do not cross a protection boundary that permissions checks would catch.

DeepYogurt  8 years ago

Possibly, but it's not uncommon to refer to x86 and x64 machines as intel architecture machines or as intel machines.

  • xenadu02  8 years ago

    Due to architectural differences, AMD CPUs are immune or nearly immune to some of the speculative execution attacks (though not all of them). For example, AMDs branch predictor uses the full address and so is not vulnerable to branch predictor poisoning in the same way as Intel.

    The major win (whether AMD intended it or not) is that AMD cpus don't speculate loads until page permissions have been verified. Intel fires off the speculation immediately. That is one of the primary side channels underlying many of the attacks.

    Intel has been actively muddying the waters with FUD to get people to think AMD is just as vulnerable. Please don’t buy into that. Intel is far more exposed. The subsequent slowdowns are more severe.