"Other operating systems" and "stealing" a bit

Posted Feb 22, 2022 20:42 UTC (Tue) by nix (subscriber, #2304)
In reply to: "Other operating systems" and "stealing" a bit by marcH
Parent article: Shadow stacks for user space

Both Intel and software on Intel processors has learned this before: in the 286 days lots of software used reserved bits freely, and then the 386 started using them and all hell broke loose. It's literally impossible to do that now, because the processor stops you.

(ref: http://www.os2museum.com/wp/theres-more-to-the-286-xenix-...)