Re: Platform specification questions
On Mon, Dec 13, 2021 at 11:06 AM Vedvyas Shanbhogue <ved@...> wrote:
>The current wording is the following.
This seems like a toothless and qualitative mandate since no FIT requirements are specified. It can be a suggestion, although it's just a qualitative suggestion. It's essentially just saying "don't forget to consider FIT requirements". One can imagine a hundred such reminders that factor into high-end silicon design. Why highlight just this one?
The reference to "cache structures" is also incomplete - as well as ambiguous as to whether it refers just to caches (in the most popular sense of the word) or also to other caching structures like TLBs as well . Most all RAM-based structures in which an error can result in functional failure, need to be protected. Although one can take the view that the above text was just trying to express a minimum requirement that doesn't encompass all RAM-based structures. My suggestion would be something like the following two statements:
Mandate: At a minimum, caching structures must be protected such that single-bit errors are detected and corrected by hardware.
Recommendation: Depending on FIT rate requirements, more advanced protection, more complete protection coverage of other structures, and/or more features may be necessary (starting with at least SECDED ECC on caching structures holding locally modified data).