I would expect the opposite. Meltdown and Spectre both make use of peeking at implicit state that chips hang on to in order to optimize microcode; the entire go

I would expect the opposite. Meltdown and Spectre both make use of peeking at implicit state that chips hang on to in order to optimize microcode; the entire goal of Itanium was to offload this optimization from the chip to the compiler. A little Googling found an analysis from someone more knowledgeable than myself that backs this up: https://secure64.com/not-vulnerable-intel-itanium-secure64-sourcet/ https://secure64.com/not-vulnerable-intel-itanium-secure64-s... tl;dr Meltdown takes advantage of out-of-order execution, which Itanium simply doesn't have. Spectre makes use of speculative execution, which Itanium only has in a version too limited to support the attack. I'm not an expert in this field so I can't attest to the credibility of this analysis. The Spectre part in particular sounds a little hand-wavy but it might just be over my head. But it aligns with my intuition, which is that the simpler and more explicit architecture doesn't have as many places where data can accidentally end up.