Re: What does atomic_read actually do?

[Brian Gerst]

Joseph Seigh wrote:
> On Sat, 18 Dec 2004 20:54:40 +0100, Arjan van de Ven 
> <arjan@xxxxxxxxxxxxx>  wrote:
>
> > On Sat, 2004-12-18 at 14:20 -0500, Joseph Seigh wrote:
> >
> > > I mean atomic in the either old or new sense.  I'm wondering what
> > > guarantees
> > > the atomicity.  Not the C standard.  I can see the gcc compiler uses 
> > > a  MOV
> > > instruction to load the atomic_t from memory which is guaranteed 
> > > atomic  by
> > > the architecture if aligned properly.  But gcc does that for any old int
> > > as far as I can see, so why use atomic_read?
> >
> >
> > it does so on *x86
>
>
> Is this documented for gcc anywhere?  Just because it does so doesn't
> mean it's guaranteed.
>
> Joe Seigh

ftp://download.intel.com/design/Pentium4/manuals/25366814.pdf

Chapter 7, section 1

--
				Brian Gerst
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