How a months-old AMD microcode bug destroyed my weekend

Enlarge / Ryzen 3000's RDRAND function-what should be a high-quality pseudo-random number generator-just returns 0xFFFFFFFFF every time, until its microcode is patched. (credit: Adobe)

This weekend, I was excited to deploy my first Ryzen 3000-powered workstation in my home office. Unfortunately, a microcode bug-originally discovered in July but still floating around in large numbers in the wild-wrecked my good time. I eventually got my Ryzen 3700X system working, and it's definitely fast. But unfortunately, it's still bugged, and there's no easy way to fix it.

Not long after the product launch, AMD Ryzen 3000 customers started noticing problems with their shiny new CPUs. Windows users couldn't successfully launch Destiny 2 (due to a power-management bug, unrelated to the one sidelining my system), and Linux users in many cases couldn't even get their system to boot. Jason Evangelho covered the initial discovery and report of the bug at Forbes back in July, and an AMD representative provided him with a statement by email:

AMD has identified the root cause and implemented a BIOS fix for an issue impacting the ability to run certain Linux distributions and Destiny 2 on Ryzen 3000 processors. We have distributed an updated BIOS to our motherboard partners, and we expect consumers to have access to the new BIOS over the coming days.

This sounds happy and upbeat, but the reality isn't quite so simple. When there's a bug in the CPU microcode, you're at the mercy of your motherboard vendor to release a new system BIOS that will update it for you-you can't just go to some download link at AMD and apply a fix yourself.

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