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Re: [Xen-devel] [PATCH 1/2] x86/SVM-IOMMU: Don't opencode memcpy() in queue_iommu_command()
>>> On 24.09.18 at 14:18, <Paul.Durrant@xxxxxxxxxx> wrote:
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: 24 September 2018 13:16
>>
>> All writes to the ring occur strictly before the update of the tail
>> pointer
>
> ...unless the compiler decides to re-order. There's no barrier.
But there is (an implied) one, inside writel() (due to the "volatile").
Everything ahead of the writel() invocation may be stored in any
order.
Jan
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