Re: [Xen-devel] [PATCH ARM v3 7/7] mini-os: initial ARM support

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Thomas Leonard, le Tue 17 Jun 2014 14:47:16 +0100, a écrit :
> I'm not sure what the difference between the synch and non-synch
> versions is supposed to be. Currently, I'm just doing:

The synch version provides memory barriers (and can thus be used for
synchronization of other things). The non-synch version only provides
atomicity.

> I used __ATOMIC_SEQ_CST as the memory model as that was the safest
> option, but maybe it's overkill.

The synch_ versions provide a full memory barrier, so seq consistency is
fine. The non-synch versions can use a completely relaxed memory model.

> The main user of these operations was gic.c, but it turns out that the
> atomic versions don't work here as the GIC registers aren't regular
> memory. So I replaced those with non-atomic versions.
> 
> Does this seem reasonable?

I guess there are other ways to make sure no two threads are accessing
GIC registers, so it is fine, yes.

Samuel

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