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They aren't. Spectre works fine on AMD. They avoided Meltdown only because their cores are less optimised. Meltdown isn't Intel specific - Apple cores were also

They aren't. Spectre works fine on AMD. They avoided Meltdown only because their cores are less optimised. Meltdown isn't Intel specific - Apple cores were also affected. It's clear that AMD weren't doing anything special w.r.t. side channel attacks. They were just further behind in the optimisation race and as a consequence, were less hit.

likeclockwork 8y ago
Can you really call "fast but wrong/insecure" optimized?
- mark-r 8y ago
  Yes you can, if it makes your benchmarks look better. That's why Intel is trying to suppress the benchmarks.
- Dylan16807 8y ago
  It doesn't calculate anything wrong, so sure. For this particular optimization, it looks better not to have it. But in general, knowing how something is flawed lets you mitigate the flaws. We use floating point despite it being mathematically wrong, because it's fast and we can mitigate the wrongness. I could imagine a chip where speculation could be toggled between different modes, if there was enough demand. I will say that "just further behind" is probably wrong. AMD has a lot of optimizations in their chips. They have safer ones, which might be luck or might be engineering talent, but it's not a mere artifact of being behind the curve.
kllrnohj 8y ago
That is a horrifically biased & wrong summary. AMD enforce privilege checks at access time rather than at retirement time. Whether or not this is due to "lack of optimization" or "good security engineering" nobody knows. But your claims that this was purely the result of "less optimised [sic]" cores is nonsense. You have zero evidence whatsoever that that was the case vs. AMD just having superior engineering on this particular aspect and not adding bugs to their architecture. All we know are that Intel & ARM CPUs have an entire category of security bugs that AMD don't, and that upon close analysis AMD's CPUs are operating in a more secure foundation.
- noobermin 8y ago
  Minor tidbit, but "optimised" is correct British spelling, so the disdainful "[sic]" is not needed.
- repolfx 8y ago
  The summary is correct and optimised is the correct spelling where I'm from. If AMD were making conscious efforts to avoid side channel attacks they'd already have had various features to show for it like IBRS. But AMD's chips say nothing about side channel attacks. Their manuals do not discuss Spectre attacks. And there is no evidence anywhere that they knew about Meltdown type attacks and chose to avoid them. I get that suddenly hating on Intel is cool and popular, but the facts remain. There is no reason to believe AMD has any advantage here.
  - kllrnohj 8y ago
    For meltdown AMD followed what the x86 spec said. It's flabbergasting you are trying to contort this into making AMD look bad. Your "summary" was basically that AMD was too incompetent to have multiple security issues. The facts are AMD does not have a significant per-core IPC defeceit vs. Intel (as supported by every ryzen review at this point) and AMD has, on multiple occasions now, had objectively superior security. You're trying to twist this into a negative against AMD. It's nonsense FUD. Intel fucked up, AMD didn't. Why are you trying to run PR damage control for Intel?
    - repolfx 8y ago
      Please show me where in the x86 spec side channel attacks are discussed at all? They aren't. I am really unsure where you're getting this from. Your reference to the spec makes me wonder if you really understand what Meltdown and Spectre are. They aren't bugs in the chips even though some such issues may be fixable with chip changes, because no CPU has ever claimed to be resistant to side channel attacks of any form. Meltdown doesn't work by exploiting spec violations or actual failures of any built in security logic, which is why - like Spectre - it surfaces in Apple chips too. Like Spectre it's a side channel attack. I'm not trying to twist this into a negative for AMD: it's the other way around, you are trying to twist this into a positive for them, although no CPU company has done any work on mitigation of micro-architectural side channel attacks. I'm simply trying to ensure readers of this discussion understand what's truly happening and do not draw erroneous conclusions about AMDs competence or understanding of side channel attacks. What you're attempting to do here is read far more into a lucky escape than is really warranted.

likeclockwork 8y ago

Can you really call "fast but wrong/insecure" optimized?

mark-r 8y ago
Yes you can, if it makes your benchmarks look better. That's why Intel is trying to suppress the benchmarks.
Dylan16807 8y ago
It doesn't calculate anything wrong, so sure. For this particular optimization, it looks better not to have it. But in general, knowing how something is flawed lets you mitigate the flaws. We use floating point despite it being mathematically wrong, because it's fast and we can mitigate the wrongness. I could imagine a chip where speculation could be toggled between different modes, if there was enough demand. I will say that "just further behind" is probably wrong. AMD has a lot of optimizations in their chips. They have safer ones, which might be luck or might be engineering talent, but it's not a mere artifact of being behind the curve.

kllrnohj 8y ago

That is a horrifically biased & wrong summary. AMD enforce privilege checks at access time rather than at retirement time. Whether or not this is due to "lack of optimization" or "good security engineering" nobody knows. But your claims that this was purely the result of "less optimised [sic]" cores is nonsense. You have zero evidence whatsoever that that was the case vs. AMD just having superior engineering on this particular aspect and not adding bugs to their architecture. All we know are that Intel & ARM CPUs have an entire category of security bugs that AMD don't, and that upon close analysis AMD's CPUs are operating in a more secure foundation.

noobermin 8y ago
Minor tidbit, but "optimised" is correct British spelling, so the disdainful "[sic]" is not needed.
repolfx 8y ago
The summary is correct and optimised is the correct spelling where I'm from. If AMD were making conscious efforts to avoid side channel attacks they'd already have had various features to show for it like IBRS. But AMD's chips say nothing about side channel attacks. Their manuals do not discuss Spectre attacks. And there is no evidence anywhere that they knew about Meltdown type attacks and chose to avoid them. I get that suddenly hating on Intel is cool and popular, but the facts remain. There is no reason to believe AMD has any advantage here.
- kllrnohj 8y ago
  For meltdown AMD followed what the x86 spec said. It's flabbergasting you are trying to contort this into making AMD look bad. Your "summary" was basically that AMD was too incompetent to have multiple security issues. The facts are AMD does not have a significant per-core IPC defeceit vs. Intel (as supported by every ryzen review at this point) and AMD has, on multiple occasions now, had objectively superior security. You're trying to twist this into a negative against AMD. It's nonsense FUD. Intel fucked up, AMD didn't. Why are you trying to run PR damage control for Intel?
  - repolfx 8y ago
    Please show me where in the x86 spec side channel attacks are discussed at all? They aren't. I am really unsure where you're getting this from. Your reference to the spec makes me wonder if you really understand what Meltdown and Spectre are. They aren't bugs in the chips even though some such issues may be fixable with chip changes, because no CPU has ever claimed to be resistant to side channel attacks of any form. Meltdown doesn't work by exploiting spec violations or actual failures of any built in security logic, which is why - like Spectre - it surfaces in Apple chips too. Like Spectre it's a side channel attack. I'm not trying to twist this into a negative for AMD: it's the other way around, you are trying to twist this into a positive for them, although no CPU company has done any work on mitigation of micro-architectural side channel attacks. I'm simply trying to ensure readers of this discussion understand what's truly happening and do not draw erroneous conclusions about AMDs competence or understanding of side channel attacks. What you're attempting to do here is read far more into a lucky escape than is really warranted.