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Re: [PATCH v3 1/2] x86: restore pv_rtc_handler() invocation

  • To: Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Mon, 20 Jul 2020 16:28:24 +0100
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  • Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Paul Durrant <paul@xxxxxxx>
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On 16/07/2020 11:06, Jan Beulich wrote:
> ACCESS_ONCE() guarantees single access, but doesn't guarantee that
> the compiler wouldn't split this single access into multiple insns.

ACCESS_ONCE() does guarantee single accesses for any natural integer size.

There is a section about this specifically in Linux's
memory-barriers.txt, and this isn't the first time I've pointed it out...




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