Re: [PATCH 2/4] atomics: update documentation for C11

[Stefan Hajnoczi]

On Mon, Apr 06, 2020 at 03:13:18PM -0400, Paolo Bonzini wrote:
> -The semantics of these primitives map to Java volatile variables,
> -and are strongly related to memory barriers as used in the Linux
> -kernel (see below).
> -
> -As long as you use atomic_mb_read and atomic_mb_set, accesses cannot
> -be reordered with each other, and it is also not possible to reorder
> -"normal" accesses around them.
> -
> -However, and this is the important difference between
> -atomic_mb_read/atomic_mb_set and sequential consistency, it is important
> -for both threads to access the same volatile variable.  It is not the
> -case that everything visible to thread A when it writes volatile field f
> -becomes visible to thread B after it reads volatile field g. The store
> -and load have to "match" (i.e., be performed on the same volatile
> -field) to achieve the right semantics.
> -
> -
> -These operations operate on any type that is as wide as an int or smaller.
> +which however are deprecated.

Please indicate why they are deprecated and advise which alternative is
preferred.  This will help readers understand the current best practices
and make a decision about whether to avoid the deprecated APIs.

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