Saturday, July 3, 2021

New top story on Hacker News: Mystery of Intel Cpuid 21H Leaf

Mystery of Intel Cpuid 21H Leaf
4 by ruik | 2 comments on Hacker News.
The latest June 2021 SDM manual volume 2A, chapter 3 added a mysterious note about CPUID leaf 21H: "Invalid. No existing or future CPU will return processor identification or feature information if the initial EAX value is 21H." Any idea why this is specified? They claim the leaf will just always return zero, or if max leaf is lower, returning the highest valid values as usual. This makes it forever just unused/unusable. But why?

No comments:

Post a Comment

Relief for Iraola but Liverpool have work to do after snatching draw at Newcastle

Dominik Szoboszlai's injury-time penalty rescues a point at the start of the Andoni Iraola era - but Liverpool need to improv after belo...