Re: [Qemu-devel] Implementing atomic SWP in qemu-arm

[Nathan Froyd]

On Wed, Aug 18, 2010 at 12:15:09PM -0700, Peter W Schultz wrote:
> How would I go about modifying the qemu source to implement SWP
> atomically? I have been studying the source for a few days now, and I
> am at a loss as to what all needs to be done.

You should look at how the load/store-exclusive instructions work and
see if you can use a similar mechanism.  It should be fairly
straightforward.

> I feel it would be most desirable to add a TCG_SWAP instruction that
> is guaranteed to be an atomic compare-and-swap, and implement that as
> needed.

I believe there was an thread several months ago discussing doing this
or something similar and it was decided that mechanism was not the way
to go.

-Nathan