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Subject: Re: [virtio-dev] [PATCH v1] VIRTIO_F_IO_BARRIER: use I/O barriers in driver
On 2018年04月28日 11:22, Jason Wang wrote:
On 2018年04月28日 11:19, Tiwei Bie wrote:On Sat, Apr 28, 2018 at 11:01:55AM +0800, Jason Wang wrote:On 2018年04月28日 10:23, Tiwei Bie wrote:Users may ask what the specific kinds of barrier here (e.g mmio barrier orThere will be hardware virtio devices in the future, which require drivers to use the barriers suitable for I/O devices, compared with software virtio devices which just require drivers to use the barriers suitable for CPU cores. To fix the ordering issue for hardware virtio devices, add a new feature: VIRTIO_F_IO_BARRIER. When negotiated, driver will use the barriers suitable for I/O devices. Signed-off-by: Tiwei Bie<tiwei.bie@intel.com> --- RFC -> v1: - Use plural (Stefan); - Add more details (Stefan); content.tex | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/content.tex b/content.tex index ae5fa4c..a1c09c4 100644 --- a/content.tex +++ b/content.tex@@ -5445,6 +5445,13 @@ Descriptors} and \ref{sec:Packed Virtqueues / Indirect Flag: Scatter-Gather Suppthat drivers pass extra data (besides identifying the Virtqueue) in their device notifications.See \ref{sec:Virtqueues / Driver notifications}~\nameref{sec:Virtqueues / Driver notifications}. + \item[VIRTIO_F_IO_BARRIER(37)] This feature indicates that the device+ needs the driver to use the barriers suitable for hardware devices.dma barrier). Do we need to clarify that?IMO it's very obvious that we need all types of barriers used in the driver should be able to work with hardware devices. Best regards, Tiwei BieJust in case I do not miss anything, is mmio barrier really needed? I believe what we need is on dma barrier here.Thanks
Ok, I think I get your meaning here. Driver should choose to use appropriate barriers though mmio barriers is not necessary for current virito. So it looks fine to me.
Thanks
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