Re: [Qemu-devel] [virtio-dev][RFC v2 2/2] virtio-sdm: new device specification

[Stefan Hajnoczi]

On Tue, Jun 28, 2016 at 01:03:44PM +0200, Christian Pinto wrote:
> +\begin{lstlisting}
> +struct virtio_sdm_config {
> +     u8    master;

The next field has 16-bit alignment so there is a hole in this struct.
Three options:

1. Add an explicit u8 padding field.
2. Change master's type from u8 to u16.
3. Move master to the end of the struct.

> +\subsection{Device Initialization}\label{sec:Device Types / SDM Device /
> +evice Initialization}
> +
> +During initialization the \texttt{hg_vq} and \texttt{gh_vq} are identified 
> and
> +the device is immediately operational. A master driver instance can access 
> the
> +number of slaves registered at any time by reading the configuration space of
> +the device.
> +
> +During the initialization phase the device connects also to the communication
> +channel. It has to be noted that the behavior of the device is
> +independent from the communication channel used, that is a detail of each
> +specific implementation of the SDM device.

How are SDM devices identified?  For example, if two SDM devices are
available, how does the driver know which one serves a particular
function?

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