If you’re reading this you’re probably already aware of the debacle that’s unfolded.
So I wont be doing any introductions here.
Instead this is intended to be a list of Processors I have identified (to within a reasonable degree) to be guaranteed immune to Meltdown and particularly the Spectre exploit.
An awesome writeup written by Eben Upton can be read here. It’s a great introduction to fundamental CPU architecture concepts.
The Spectre & Meltdown vulnerability relies on a CPU making use of speculative execution specifically tied with branch prediction, together with Out of order execution architecture processors. Spectre should not work against in-order execution processors without branch prediction or other speculative features. But there are some in-order execution processors with branch prediction and speculative issuing that are immune. (See Cortex-A53) And some that are not. (See Cortex-A8)
Before we had out of order and speculative execution architectures however, we had in-order execution. Processors that would faithfully execute one instruction after another, often wasting a lot of cycles because some instructions take longer than others.
I wont explain these architectural differences here, the linked Wiki pages and materials are best referenced as a good starting point.
It is these faithful old fashioned in-order execution CPU’s which due to their rigorous sequential execution are immune to Spectre. Now you may be thinking, wait these can only be really old CPU’s! And you’d be wrong! They however certainly aren’t the fastest CPU’s, but if you need something to be tinfoil hat secure, this is where you’d look.
Things I’m not 100% sure of:
(But has a better chance than anything not on this list)
- SPARC T Series (T3 and up)
Things I was wrong about:
Stuff that’s got interesting features to disrupt/disable Spectre
- AMD Zen with SME/SEV (Secure Memory Encryption/Secure Encrypted Virtualization)
- This would garble any retrieved memory in Virtualization scenarios.
See this old thread of mine for all of the resources.