Messages in this thread | | | From | Ohad Ben-Cohen <> | Date | Wed, 30 Nov 2011 18:24:16 +0200 | Subject | Re: [RFC] virtio: use mandatory barriers for remote processor vdevs |
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On Wed, Nov 30, 2011 at 6:15 PM, Michael S. Tsirkin <mst@redhat.com> wrote: > How are the rings mapped? normal memory, right?
No, device memory.
> We allocate them with plan alloc_pages_exact in virtio_pci.c ...
I'm not using virtio_pci.c; remoteproc is allocating the rings using the DMA API.
> Yes wmb() is required to ensure ordering for MMIO. > But here both accesses: index and ring - are for > memory, not MMIO.
I'm doing IO with a device over shared memory. It does require mandatory barriers as I explained.
> Is this something you see in practice?
Yes. These bugs are very real.
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