Re: [PATCH v2 2/6] notifications: notifications as basic virtio facility

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 11 Jun 2018 18:11:54 +0200
Halil Pasic <pasic@linux.ibm.com> wrote:

> Let's introduce notifications as basic virtio facility early on. This
> shall not only increase the cohesion between core and transport
> description by having a well-defined  place where notifications are
> introduced, but also give us the opportunity to explain some
> discrepancies.
> 
> Namely notifications sent by the device to the driver were often called
> interrupts prior to v1.1. Getting completely rid of that terminology is
> however not viable in case of some names.
> 
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>  content.tex |   36 ++++++++++++++++++++++++++++++++++++
>  1 files changed, 36 insertions(+), 0 deletions(-)
> 
> diff --git a/content.tex b/content.tex
> index e1dcaea..3aa9be8 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -8,6 +8,7 @@ device consists of the following parts:
>  \begin{itemize}
>  \item Device status field
>  \item Feature bits
> +\item Notifications
>  \item Device Configuration space
>  \item One or more virtqueues
>  \end{itemize}
> @@ -150,6 +151,41 @@ requirements documented within these legacy interface sections.
>  Specification text within these sections generally does not apply
>  to non-transitional devices.
>  
> +\section{Notifications}\label{sec:Basic Facilities of a Virtio Device
> +/ Notifications}
> +
> +The notion of sending a notification (driver to device or device
> +to driver) plays an important role in this specification. The
> +modus operandi of the notifications is transport specific.
> +
> +There are three types of notifications: 
> +\begin{itemize}
> +\item device configuration space notification

Shouldn't that be "configuration _change_ notification"?

> +\item available buffer notification
> +\item used buffer notification. 
> +\end{itemize}
> +
> +Device configuration space notifications and used buffer notifications
> +are sent by the device, the recipient is the driver. A device
> +configuration space notification indicates that a configuration space
> +has changed; a used buffer notification indicates that a buffer may
> +have been made used on the virtqueue designated by the notification.
> +
> +Available buffer notifications are sent by the driver, the recipient is
> +the device. This type of notification indicates that a buffer may have
> +been made available on the virtqueue designated by the notification.
> +
> +The semantic, the transport-specific implementations and other
> +important aspects of the different notifications are specified in detail
> +in the following chapters.
> +
> +Most transports implement notifications sent by the device to the
> +driver using interrupts. Therefore, in previous versions of this
> +specification, these notifications were often called interrupts.
> +Some names defined in this specification still retain this interrupt
> +terminology. Occasionally, the term event is used to refer to
> +a notification or a receipt of a notification.
> +
>  \section{Device Configuration Space}\label{sec:Basic Facilities of a Virtio Device / Device Configuration Space}
>  
>  Device configuration space is generally used for rarely-changing or