Blacksmith – Rowhammer bit flips on all DRAM devices today despite mitigations

Re:Blacksmith – Rowhammer bit flips on all DRAM devices toda... by wolf550e on Monday November 15, 2021 @12:27PM (#29229903)

It's unlikely a different die (silicon chip), so the usual number of cores and usual size of caches, and it's unlikely that AWS gets a secret x86 instruction unlockable via msr or something like that. It's probably just constants for the frequency scaling (e.g. all cores and single core turbo).

Cloudflare mentioned they use a custom Intel SKU on their blog, and they're not as big as AWS.

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Re:Blacksmith – Rowhammer bit flips on all DRAM devices toda... by ghbe44 on Monday November 15, 2021 @01:03PM (#29230361)

I’m familiar with Google’s custom SKUs, and I assure you they’re unique enough to experience microcode bugs nobody else on the planet ever hits. There was a weird FDIV one back in the day that wasn’t the same FDIV bug that hit us all a long time ago. Cloudflare isn’t really at that customization table.

Your take sounds accurate for non-FAANGs (and a couple of those). For Google, not so much. There is a lot of custom acceleration and such that isn’t available to any other customer, and a nearby commenter is right, every detail about them is locked behind a very strong NDA. I’ve heard thirdhand AWS does indeed have custom instructions in the virtualization extensions stuff, but don’t know if that’s true.

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Re:Blacksmith – Rowhammer bit flips on all DRAM devices toda... by monocasa on Monday November 15, 2021 @02:02PM (#29231194)

My understanding is that Google's SKUs are the same die. Non Google versions just have the Google specific silicon fused off, or require a MSR knock sequence to turn on.

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