Re: [virtio] [PATCH v7 06/11] content: generalize rest of text

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Jan 30, 2018 at 11:31:18AM +0100, Cornelia Huck wrote:
> On Tue, 23 Jan 2018 02:01:05 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  content.tex | 14 ++++++--------
> >  1 file changed, 6 insertions(+), 8 deletions(-)
> > 
> > diff --git a/content.tex b/content.tex
> > index 9fc9673..5634c7d 100644
> > --- a/content.tex
> > +++ b/content.tex
> > @@ -1467,8 +1467,7 @@ All register values are organized as Little Endian.
> >    }
> >    \hline 
> >    \mmioreg{QueueNum}{Virtual queue size}{0x038}{W}{%
> > -    Queue size is the number of elements in the queue, therefore in each
> > -    of the Descriptor Table, the Available Ring and the Used Ring.
> > +    Queue size is the number of elements in the queue.
> >      Writing to this register notifies the device what size of the
> >      queue the driver will use. This applies to the queue selected by
> >      writing to \field{QueueSel}.
> > @@ -1491,9 +1490,9 @@ All register values are organized as Little Endian.
> >      caused the device interrupt to be asserted.
> >      The following events are possible:
> >      \begin{description}
> > -      \item[Used Ring Update] - bit 0 - the interrupt was asserted
> > -        because the device has updated the Used
> > -        Ring in at least one of the active virtual queues.
> > +      \item[Used Buffer Update] - bit 0 - the interrupt was asserted
> > +        because the device has used a buffer
> > +        in at least one of the active virtual queues.
> >        \item [Configuration Change] - bit 1 - the interrupt was
> >          asserted because the configuration of the device has changed.
> >      \end{description}
> > @@ -1642,9 +1641,8 @@ The driver will typically initialize the virtual queue in the following way:
> >     \field{QueueNumMax}. If the returned value is zero (0x0) the
> >     queue is not available.
> >  
> > -\item Allocate and zero the queue pages, making sure the memory
> > -   is physically contiguous. It is recommended to align the
> > -   Used Ring to an optimal boundary (usually the page size).
> > +\item Allocate and zero the queue memory, making sure the memory
> > +   is physically contiguous.
> 
> What about recommendations of that type? Will we want some kind of
> "best practice" suggestions (layout and/or transport specific?)

I don't really know what was this in aid of. When is page size an
optimal boundary? I suspect it never is.  I suspect cache line alignment
is a good idea generally but I'm not sure.  Want to write something up?
It's also unlikely to be transport specific.

> >  
> >  \item Notify the device about the queue size by writing the size to
> >     \field{QueueNum}.
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>