Re: [PATCH 0/3] Add OMAP hardware spinlock misc driver

Peter Zijlstra
2010-10-18T14:33:03Z

On Mon, 2010-10-18 at 16:28 +0200, Ohad Ben-Cohen wrote:
> On Mon, Oct 18, 2010 at 3:43 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > Right, so the problem is that there simply is no way to do atomic memory
> > access from these auxiliary processing units wrt the main CPU?
>
> Yes. There are a few relevant system-wide limitations, one of them is
> that simply the system interconnect does not support those fancy
> atomic operations.

Does it support full memory coherency though? Otherwise I can see memory
based message passing becoming rather interesting.

Without coherency everybody needs to be damn sure to flush the relevant
bits before unlocking and such.