On Fri, 26 Aug 2011 15:40:08 +1000, David Gibson <da...@gibson.dropbear.id.au>
wrote:
> Near the top of hw/virtio.c we have this:
>
> /* QEMU doesn't strictly need write barriers since everything runs in
> * lock-step. We'll leave the calls to wmb() in though to make it
> obvious for
> * KVM or if kqemu gets SMP support.
> * In any case, we must prevent the compiler from reordering the code.
> * TODO: we likely need some rmb()/mb() as well.
> */
>
> #define wmb() __asm__ __volatile__("": : :"memory")
>
>
> However, as far as I can tell when using both kvm and io-thread, the
> assertion that barriers aren't necessary just isn't true. Although it
> probably works on x86 with its strongly ordered model.
That looks very much like it's cribbed from the original lguest code.
Very wrong, please fix!
Thanks,
Rusty.
