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

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Thomas Leonard, le Wed 18 Jun 2014 08:55:45 +0100, a écrit :
> On 17 June 2014 23:53, Samuel Thibault <samuel.thibault@xxxxxxxxxxxx> wrote:
> > 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.
> 
> OK, so does that mean that e.g. this comment in x86/os.h is wrong?
> 
> /**
>  * test_and_clear_bit - Clear a bit and return its old value
>  * @nr: Bit to clear
>  * @addr: Address to count from
>  *
>  * This operation is atomic and cannot be reordered.
>  * It also implies a memory barrier.
>  */

Yes, it is wrong: LOCK is apparently defined to "".

Samuel

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