lkml.org 
[lkml]   [2011]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [RFC] virtio: use mandatory barriers for remote processor vdevs
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.


\
 
 \ /
  Last update: 2011-11-30 17:27    [W:0.089 / U:0.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site