Re: [PATCH 4/8] edu: add smp_mb__after_rmw()

[Paolo Bonzini <pbonzini@redhat.com>]

On 3/6/23 15:24, Peter Maydell wrote:
>>> Why is this device even messing around with multiple
>>> threads and atomics anyway ??
>> Because it is an example of deferring device work to another thread,
>> just like on real hardware it may be deferred to an on-device
>> microcontroller or CPU.
> If we want to be able to do that, we should probably have
> infrastructure and higher-level primitives for it that
> don't require device authors to be super-familiar with
> QEMU's memory model and barriers... The fact there are only
> half a dozen other uses of qemu_thread_create() under hw/
> suggests that in practice we don't really need to do this
> very often, though.

Yes, you're totally right about that.  I have never needed this kind of 
higher-level primitive so I haven't thought much about what it would 
look like.

The usage of barriers isn't great, but all this patch does is correctness...

Paolo