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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

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.
  - kllrnohj 8y ago
    Meltdown was enabled by a clear-cut violating of the memory access restrictions of x86. Intel simply did the permission check at the wrong point in the pipeline. It's not anything more obscure or clever than that, and it wasn't even an optimization as the end-to-end latency remains the same. It still did all the work, it just did it in the wrong order. Permission check was done after read access was done anyway. Memory was accessed that the spec says was not accessible. This has nothing to do with side-channels. The side channel part of the attack was how the spec violation was exploited. For Meltdown specifically Intel fucked up, AMD didn't. This is not at all vague. Whether or not this was due to luck or not is irrelevant, it was clearly NOT due to incompetence as you were pushing. You pushed a narrative that AMD was too incompetent ("missing optimization") to have a severe security bug. That has nothing to do with reality whatsoever. Side note, side channel attacks are not exactly obscure. Guaranteed AMD & Intel have security experts that are well aware of how side channel attacks work long before any of meltdown & spectre came to light. They have been around for ages. Practical exploits of L1/L2 cache via mechanisms like Prime+Probe date back at least as far as 2005: https://eprint.iacr.org/2005/271.pdf https://eprint.iacr.org/2005/271.pdf

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.
- kllrnohj 8y ago
  Meltdown was enabled by a clear-cut violating of the memory access restrictions of x86. Intel simply did the permission check at the wrong point in the pipeline. It's not anything more obscure or clever than that, and it wasn't even an optimization as the end-to-end latency remains the same. It still did all the work, it just did it in the wrong order. Permission check was done after read access was done anyway. Memory was accessed that the spec says was not accessible. This has nothing to do with side-channels. The side channel part of the attack was how the spec violation was exploited. For Meltdown specifically Intel fucked up, AMD didn't. This is not at all vague. Whether or not this was due to luck or not is irrelevant, it was clearly NOT due to incompetence as you were pushing. You pushed a narrative that AMD was too incompetent ("missing optimization") to have a severe security bug. That has nothing to do with reality whatsoever. Side note, side channel attacks are not exactly obscure. Guaranteed AMD & Intel have security experts that are well aware of how side channel attacks work long before any of meltdown & spectre came to light. They have been around for ages. Practical exploits of L1/L2 cache via mechanisms like Prime+Probe date back at least as far as 2005: https://eprint.iacr.org/2005/271.pdf https://eprint.iacr.org/2005/271.pdf